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Objectives: This study evaluated the accuracy of the Medit i700 intraoral scanner (IOS) in capturing horizontal tooth preparations at different depths below the gingival margin and assessed its ability to detect surfaces beyond the finish line., Methods: Using CAD software, two abutments of a standard maxillary first molar were designed with horizontal preparation and 0.8 mm chamfer at 1 mm and 2 mm depths below the gingival margin. The abutment designs, created in DentalCAD 3.0 Galway (Exocad), were 3D printed and mounted on a typodont with simulated pink gum. An experienced operator conducted 20 scans, with each scan taking between 1 and 2 min. The scanning process began at the occlusal surface of the right third molar and proceeded longitudinally to the contralateral molar, then extended buccally and palatally, resulting in two experimental groups: H-1 (1 mm depth) and H-2 (2 mm depth). Accuracy was assessed using Geomagic Control X software, with descriptive statistics and independent sample tests (α = 0.05) employed for group comparisons., Results: No statistically significant difference was found in trueness between H-1 and H-2 (p=.053). However, precision differed significantly (p<.001). The IOS could not capture surfaces beyond the finish line in horizontal preparations., Conclusions: Within study limitations, the horizontal preparation design hindered the IOS's ability to capture tooth anatomy beyond the finish line. Nonetheless, accuracy values at both 1 mm and 2 mm depths were clinically acceptable., Clinical Significance,: The present study shows that the tested intraoral scanner is accurate enough to scan abutments with horizontal margins placed 1 and 2 mm below the gingiva., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

Purpose: This study investigated the influence of different palatal morphologies on the accuracy of intraoral scanning (TRIOS 4) of edentulous maxillae., Methods: Six typodonts were fabricated for different palatal morphologies with flat (F), medium (M), and deep (D) palates, with palatal wrinkles (W), or smooth palates (S), resulting in six groups: WF, WM, WD and SF, SM, SD. Ten scans were performed for each group; standard tessellation language files obtained were imported into a software to measure trueness and precision in micrometer. Trueness was calculated as the mean of the standard deviation values obtained by superimposing each scan onto the reference scan. Precision was achieved by overlapping each scan with that with the best trueness in the group. Descriptive and post-hoc analyses were conducted., Results: The mean values for trueness were as follows: WM=48.7±4.7, WD=161.7±18.4, WF=85.9±16, SM=48.1±2.4, SD=349.9±8.8, and SF=349.1±25.5. The precision values were as follows: WM=46.7±7.3, WD=46.9±9, WF=48.9±6.7, SM=46±2.7, SD=105.9±17.4, SF=72.6±10.8. Significant differences were observed for trueness between SM and SD (P < 0.001), SM and SF (P < 0.001), and WF and SF (P = 0.003); whereas for precision, significant differences were reported between WD and SD (P = 0.015). Regarding trueness and precision, no difference was found between WM and SM (P = 1.0)., Conclusions: Medium palatal depth showed the best accuracy. The mean accuracy values were within the clinical acceptability thresholds for all palatal morphologies. The presence of rugae improved the precision of deeper palates and the trueness of flat palates. No differences were observed in the medium palates with or without rugae.

This retrospective study aimed at evaluating the clinical outcomes of lithium disilicate prostheses onto teeth and implants. A total of 860 restorations were delivered to 312 patients, including crowns, veneers and onlays. Patients with uncontrolled gingival inflammation and/or periodontitis were excluded, whilst subjects with occlusal parafunctions were included. The retrospective observational period ranged between 13 to 17 years. The mechanical and esthetic performances of the restorations were rated according to the modified CDA criteria. The recorded data were analyzed statistically. In total, 26 mechanical complications were noticed: 17 ceramic chippings, 5 core fractures and 4 losses of retention. Mechanical complications occurred predominantly in posterior areas; monolithic prostheses showed the lowest percentage of structural problems. The clinical scores of layered and monolithic restorations were fully satisfactory according to the modified CDA rating. The cumulative survival and success rates ranged between 95.46-100% and 93.75-100% respectively up to 17 years of follow-up. Although patient selection and the rigorous application of validated clinical protocols were considered paramount, the use of lithium disilicate prostheses onto teeth and implants was reported to be a viable and reliable treatment option in the long-term.

Objectives: This study aimed to evaluate the accuracy of an intraoral scanner (IOS - Medit i700) on tooth abutments with vertical preparations at 2 depths below the free gingival margin, and to determine if the IOS can reproduce the area beyond the finish surface of the tested preparation geometry., Methods: Two abutments for a maxillary first molar were designed by means of CAD software, with vertical preparations set at 1 and 2 mm below the gingiva. These abutments were subsequently printed in resin and placed on a reference model. The reference files consisted of scans made using a metrological machine on these abutments. Ten scans were made with the tested IOS on each sample, resulting in two study groups. The scans from the experimental groups were labeled "V-1″ for vertical preparation at 1 mm below the gingival margin and "V-2″ for 2 mm below. The analysis of these scans was performed using Geomagic Control X (3D SYSTEMS) to assess their trueness and precision in µm. Descriptive statistics with a 95 % confidence interval were employed, alongside independent sample tests, to ascertain any differences between the groups (α=0.05)., Results: Statistically significant differences were not found both for trueness (p=.104) and precision (p=.409), between the tested geometries. The mean values for trueness were V-1 = 37.5[31.4-43.6]; V-2 = 32.6[30.6-34.6]. About the precision, the mean values were V-1 = 20.5[8.4-32.5]; V-2 = 18.4[8.2-28.5]. In both the study groups, it was possible to detect the surface beyond the finish area., Conclusions: Within the limitations of this study, vertical preparation design allows for registration of the tooth anatomy beyond the finish area with IOS. Moreover, the mean accuracy values were clinically acceptable at both 1 and 2 mm below the gingival margin., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

Purpose: To evaluate clinical performances of two lithium disilicate systems (Initial LiSi press vs Initial LiSi Block, GC Co.) using modified United States Public Health Service (USPHS) evaluation criteria and survival rates after 4 years of clinical service., Methods: Partial adhesive crowns on natural abutment posterior teeth were made on 60 subjects who were randomly divided into two groups: Group 1: Initial LiSi press and Group 2: Initial LiSi Block. Fabrication of partial crowns was made with full analog and digital procedure in Groups 1 and 2 respectively. The restorations were followed-up for 1 and 4 years, and the modified USPHS evaluation was performed at baseline and each recall together with periodontal evaluation. Contingency tables to assess for significant differences of success over time in each group and time-dependent Cox regression to test for differences between the two groups were used and the level of significance was set at P< 0.05., Results: Regarding modified USPHS scores, all evaluated parameters showed Alpha or Bravo and no Charlie was recorded. No statistically significant difference emerged between the two groups in any of the assessed variables (P> 0.05). No statistically significant difference between scores recorded at the baseline and each recall. All modified USPHS scores were compatible with the outcome of clinical success and no one restoration was replaced or repaired, and the survival rate was 100% after 4 years of clinical service. No difference was found between traditional and digital procedure to fabricate the crowns. The two lithium disilicate materials showed similar results after 4 years of clinical service., Clinical Significance: The crowns made with the two tested lithium disilicate materials with analog and digital procedures showed 100% survival after 4 years of clinical service with no statistically significant difference using the modified USPHS scores., Competing Interests: The authors declared they had no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright©American Journal of Dentistry.)

Purpose: To evaluate the trueness, precision, time efficiency, and cost of three different workflows for manufacturing single crowns (SCs)., Methods: A plaster model with a prepared tooth (#15) was scanned with an industrial scanner, and an SC was designed in computer-assisted-design (CAD) software. Ten SCs were printed with a hybrid composite (additive chairside) and a stereolithographic (SLA) printer (Dfab®), 10 SCs were milled in lithium disilicate (subtractive chairside) using a chairside milling unit (inLab MC XL®), and 10 SCs were milled in zirconia (lab-based) using a five-axis laboratory machine (DWX-52D®). All SCs were scanned with the same scanner after polymerization/sinterization. Each scan was superimposed to the marginal area of the original CAD file to evaluate trueness: absolute average (ABS AVG), root mean square (RMS), and (90˚-10˚)/2 percentile were calculated for each group. Marginal adaptation and quality of the occlusal and interproximal contact points were also investigated by two prosthodontists on 3D printed and plaster models. Finally, the three workflows' time efficiency and costs were evaluated., Results: Additive chairside and subtractive lab-based SCs had significantly better marginal trueness than subtractive chairside SCs in all three parameters (ABS AVG, p < 0.01; RMS, p < 0.01; [90˚-10˚]/2, p < 0.01). However, the two prosthodontists found no significant differences between the three manufacturing procedures in the quality of the marginal closure (p = 0.186), interproximal (p = 0.319), and occlusal contacts (p = 0.218). Both time efficiency and cost show a trend favoring the chairside additive workflow., Conclusions: Chairside additive technology seems to represent a valid alternative for manufacturing definitive SCs, given the high marginal trueness, precision, workflow efficiency and low costs., Statement of Clinical Relevance: Additive chairside manufacturing of definitive hybrid composite SCs is now possible and shows high accuracy, time efficiency, and competitive cost., Competing Interests: Declaration of Competing Interest The authors report no conflict of interest related to this work. No grants, funding nor financial support was obtained for the preparation of the present study., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Objectives: To answer the PICO(S) question: Is there a difference in clinical longevity between direct and indirect resin composite restorations placed on permanent posterior teeth?, Data: Randomized controlled clinical trials (RCTs) investigating direct and indirect resin composite restorations in posterior permanent teeth were considered., Sources: Several electronic databases were searched, with no language or date restrictions. The revised Cochrane Collaboration's tool for assessing risk of bias (RoB-2) was used to analyze the studies; meta-analyses were run and the certainty of evidence was assessed by the GRADE tool. A subgroup meta-analysis was performed for resin composite restorations placed on posterior worn dentition., Study Selection: Twenty-three articles were included in qualitative synthesis, while 8 studies were used for meta-analyses. According to the RoB-2 tool, 5 studies were ranked as "low risk", 7 had "some concerns", while 11 papers were rated as "high risk" of bias. There were no statistically significant differences in short-term (p = 0.27; RR=1.54, 95% CI [0.72, 3.33]), medium-term (p = 0.27; RR=1.87, 95% CI [0.61, 5.72]) and long-term longevity (p = 0.86; RR=0.95, 95% CI [0.57, 1.59]). The choice of restorative technique had no influence on short-term survival of resin composite restorations placed on worn dentition (p = 0.13; RR=0.46, 95% CI [0.17, 1.25]). The certainty of evidence was rated as "very low"., Conclusions: Direct and indirect resin composite restorations may show similar clinical longevity in posterior region, regardless of the observation period or substrate (wear-affected and non-affected dentition). The very low quality of evidence suggests that more long-term RCTs are needed to confirm our results., Competing Interests: Declaration of Competing Interest The authors declare no conflict of interest., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Statement of Problem: Manufacturers of several intraoral scanners have recommended a 2-step strategy for scanning the edentulous mandible. The 2-step technique requires scanning one side first and then moving to the other side. However, whether inconsistency in stitching occurs that results in loss of accuracy or distortion is unclear., Purpose: The purpose of this clinical study was to measure the potential distortion of intraoral scans of edentulous mandibular arches made with a 2-step scanning strategy and to assess their differences with conventional impressions., Material and Methods: Twenty mandibular edentulous arches were scanned by 1 investigator with an intraoral scanner using a 2-step scanning strategy, and a corresponding polysulfide conventional impression was obtained. The conventional impression was then immediately scanned with the same intraoral scanner. The obtained standard tessellation language (STL) files were superimposed with a surface-matching software program. After a preliminary alignment, the STL meshes were trimmed and reoriented; then, the final alignment was carried out and meshes moved to a metrology software program where their mean distance was measured. In addition, a surface curve (SIOS) was traced on the intraoral scan from the right to left retromolar pad along the residual ridge and automatically projected onto to the conventional impression scan to obtain a new curve (SC). The mean distance between SIOS and SC was measured and recorded as an indicator of the distortion by considering the X-, Y-, and Z-axes and the overall 3-dimensional (3D) deviation. The analysis was performed for the full curve length and after dividing it into 6 regions of interest. Univariate and multivariate statistical analyses were used to investigate the significance of the extent of the mean 3D distance, as well as the effects of measurement positions (side and region) between and within patients on differences along the X-, Y-, and Z-axes (α=.05)., Results: The mean (-0.08 mm; standard error: 0.025) 3D distance between the intraoral scan and conventional impression was significantly different from zero (P=.003). No significant effect of the factor "side" was found by using generalized estimated equation models for the X-, Y-, and Z-axes, and global 3D deviations between SIOS and SC (P>.05), which appeared to exclude distortion. Conversely, a significant effect was found for the factor "region" (P<.05), with no significant differences (P>.05) between corresponding regions on the 2 sides., Conclusions: Intraoral scans of the edentulous mandibular arch made in a 2-step procedure did not exhibit significant distortion in comparison with conventional impressions., (Copyright © 2023 Editorial Council for The Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

This is a showcase for technical description of a full digital workflow aimed to reconstruct and prosthetically rehabilitate the mandible after surgical resection. The surgery was performed following a computer-aided design and computer-aided manufacturing (CAD-CAM) guided workflow, using 3D reconstruction of the mandible and the fibula. After 2 years, when the ossification of the flap was reached and verified by a computed tomography (CT) scan, surgery was performed using a two-step implant rehabilitation, with successful outcomes.

Objective: SARS-CoV-2 is a new Coronavirus identified as the cause of Coronavirus disease in 2019 (COVID-19). The epidemic spread in China and beyond its borders, involving 114 countries with more than 5 million dead. On March 11, the WHO declared the spread of SARS-CoV-2 to be a pandemic and encouraged nations to adopt harsh restrictive measures. Therefore, patients more and more often turn to dental offices only for emergencies. Healthcare professionals, including dentists, are at high infectious risk. In fact, the closeness to the oral cavity and nasopharynx and the use of drills or ultrasonic devices that cause aerosol release, make dental professions at high risk of bacterial and viral infections. The way patients are treated has changed. In fact, it should be mandatory to carry out a pre-treatment telephone triage and the use of mouthwashes to reduce bacterial load. In the current pandemic, it is necessary to adopt specific safety protocols that can protect dental operators as well as limit the spread of the virus. The purpose of this review is to present an overview on ways to reduce the risk of SARS-CoV-2 contagion in dentistry by focusing on the immediate situation as well as by looking towards the future., Materials and Methods: To reach the review purpose, we selected a series of studies using keywords "COVID-19" OR "SARS-CoV-2" in association with "dentistry" AND "safety protocols" AND "healthcare procedures" AND "individual protection dispositive" AND "air transmission" AND "droplet". We selected papers exclusively in English language, up to 1st January 2022., Results: During future phases of the pandemic, everywhere in the World, it is necessary to impose all dentistry team both a serological screening and the vaccination, as already established for all health staff in Italy., Conclusions: For own safety, it is an important for the whole dentistry category constantly update the devices and the protocols adopted, as well as monitoring the real infectious threats, which may occur.

Background: To assess the quantity of dentin exposure detected by 3 operators with different clinical expertise for 2 designs of tooth preparation for laminate veneers: window (WI) and butt joint (BJ). Methods: 20 intact maxillary central incisors were collected and then prepared for laminate veneers to a depth of 0.6 mm, with a cervical mini-chamfer finish line of 0.3 mm. Each prepared tooth was analyzed by 3 operators with different expertise: undergraduate student (ST), general practitioner (GP), and prosthodontist (PR), at sight under magnification. Besides descriptive statistics (CI 95%), 2-way ANOVA and Games−Howell tests were used to analyze differences among groups (α = 0.05). Results: The means of percentage and area of detected dentin exposure were WI = 30.48%, 21.57 mm2; BJ = 30.99%, 21.97 mm2; ST/WI = 22.82%, 16.44 mm2; GP/WI = 58.05%, 40.64 mm2; PR/WI = 10.55%, 7.63 mm2; ST/BJ = 28.99%, 20.83 mm2; GP/BJ = 40.56%, 28.32 mm2; PR/BJ = 23.42%, 16.75 mm2. Significant differences were found between ST/WI vs. GP/WI (p = 0.005) and GP/WI vs. PR/WI (p < 0.001). Conclusions: There was no difference in detection of exposed dentin among operators with different expertise for BJ preparation, whereas differences were found between the general practitioner and the other 2 operators in WI. Moreover, the quantity of exposed dentin was not related to different tooth preparation designs.

Purpose: To compare the trueness and precision of 3D-printed versus milled monolithic zirconia crowns (MZCs)., Methods: A model of a maxilla with a prepared premolar was scanned with an industrial scanner (ATOSQ®, Gom) and an MZC was designed in computer-assisted-design (CAD) software (DentalCad®, Exocad). From that standard tessellation language (STL) file, 10 MZCs (test) were 3D-printed with a Lithography-based Ceramic Manufacturing (LCM) printer (CerafabS65®, Lithoz) and 10 MZCs (control) were milled using a 5-axis machine (DWX-52D®, DGShape). All MZCs were sintered and scanned with the aforementioned scanner. The surface data of each sample (overall crown, marginal area, occlusal surface) were superimposed to the original CAD file (ControlX®, Geomagic) to evaluate trueness: (90-10)/2, absolute average (ABS AVG) and root mean square (RMS) values were obtained for test and control groups (MathLab®, Mathworks) and used for analysis. Finally, the clinical precision (marginal adaptation, interproximal contacts) of test and control MZCs was investigated on a split-cast model printed (Solflex350®, Voco) from the CAD project, and compared., Results: The milled MZCs had a significantly higher trueness than the 3D-printed ones, overall [(90-10)/2 printed 37.8 µm vs milled 21.2 µm; ABS AVG printed 27.2 µm vs milled 15.1 µm; RMS printed 33.2 µm vs milled 20.5 µm; p = 0.000005], at the margins [(90-10)/2 printed 25.6 µm vs milled 12.4 µm; ABS AVG printed 17.8 µm vs milled 9.4 µm; RMS printed 22.8 µm vs milled 15.6 µm; p= 0.000011] and at the occlusal level [(90-10)/2 printed 50.4 µm vs milled 21.9 µm; ABS AVG printed 29.6 µm vs milled 14.7 µm; RMS printed 38.9 µm vs milled 22.5 µm; p = 0.000005]. However, with regard to precision, both test and control groups scored highly, with no significant difference either in the quality of interproximal contact points (p = 0.355) or marginal closure (p = 0.355)., Conclusions: Milled MZCs had a statistically higher trueness than 3D-printed ones; all crowns, however, showed high precision, compatible with the clinical use., Clinical Significance: Although milled MZCs remain more accurate than 3D-printed ones, the LCM technique seems able to guarantee the production of clinically precise zirconia crowns., (Copyright © 2021. Published by Elsevier Ltd.)

Objectives: The present narrative review was focused on the optical properties, surface treatment, adhesion, and clinical indications of zirconia-reinforced lithium silicate ceramics (ZLS) for Computer-aided design / Computer-aided manufacturing (CAD/CAM) technologies., Data/sources: A literature search was performed by 3 calibrated independent researchers on PubMed, Scopus, Embase, Google Scholar, Dynamed, and Open Grey. The criteria for inclusion were: 1) papers addressing at least one of the following variables about ZLS: optical properties, surface treatment, adhesion, and clinical indications; 2) in vitro, in silico, or in vivo studies; 3) case reports; 4) systematic reviews. The exclusion criteria were: 1) animal studies; 2) non-dental studies; 3) studies only focusing on ZLS used in the heat-pressed process., Study Selection: 98 records among in vitro studies and case reports were included., Conclusions: Despite the promising microstructure characteristics of ZLS, increased translucency compared to lithium disilicate ceramics (LS 2 ) was not proven, but acceptable color changes and stability were reported. Mechanical polishing was the most effective method to reduce surface roughness. Moreover, machinability and handling of ZLS resulted harder than LS 2 . Conventional acid etching procedures seemed effective in conditioning ZLS surface, but no protocol has been established yet. Besides, silane-coupling and dual-curing resin cements were recommended., Clinical Significance: ZLSs can be used for anterior and posterior fixed single-unit CAD/CAM restorations onto both natural teeth and implants, but do not seem to represent a viable treatment option for endocrowns onto posterior teeth or fixed dental prostheses., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Objectives: This paper aimed to provide a literature review of the mechanical and biological properties of zirconia-reinforced lithium silicate glass-ceramics (ZLS) in Computer-aided design / Computer-aided manufacturing (CAD/CAM) systems., Data/sources: An extensive search of the literature for papers related to ZLS was made on the databases of PubMed/Medline, Scopus, Embase, Google Scholar, Dynamed, and Open Grey. The papers were selected by 3 independent calibrated reviewers., Study Selection: The search strategy produced 937 records. After the removal of duplicates and the exclusion of papers that did not meet the inclusion criteria, 71 papers were included., Conclusions: After reviewing the included records, it was found that two types of ZLS (Vita Suprinity PC; Vita Zahnfabrik and Celtra Duo; Dentsply Sirona) are nowadays available on the market for CAD/CAM systems, similar in their chemical composition, microstructure, and biological-mechanical properties. ZLS is reported to be a biocompatible material, whose fracture resistance can withstand physiological chewing loads. The firing process influences the improvements of strength and fatigue failure load, with a volumetric shrinkage. To date, ZLS can be considered a viable alternative to other glass-ceramics for fixed single restorations., Clinical Significance: . As to biocompatibility and mechanical properties of ZLS, data are still scarce, often controversial and limited to short-term observational periods. These promising ceramics require further in vitro/in vivo studies to accurately define mechanical and biological properties, mainly in the long-term performance of restorations produced with such materials., (Copyright © 2021 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background: The aim of this randomized controlled trial was to evaluate the capability of an IOS (Intra Oral Scanner) device, used in standardized conditions, to detect margins of abutments prepared with knife-edge finishing line located at three different levels in relation to the gingival sulcus., Methods: sixty abutment teeth for treatment with full crowns were selected and randomly divided in three groups accordingly to the depth of the finishing line: Group A: supragingival margin; Group B: 0.5-1.0 mm into the sulcus; Group C: 1.5-2.0 mm into the sulcus. Temporary crowns were placed for two weeks and then digital impressions (Aadva IOS 100, GC, Japan) were made of each abutment. As controls, analog impressions were taken, poured, and scanned using a laboratory scanner (Aadva lab scanner, GC, Japan). Two standard tessellation language (STL) files were generated for each abutment, subsequently processed, and superimposed by Exocad software (Exocad GmbH, Darmstadt, Germany), applying the "best-fit" algorithm in order to align the scan of the conventional with the digital impressions. The distances between each preparation margin and the adjacent gingival tissue were measured. Four measures were taken, two interproximally and buccally, for a total of six measures of each abutment considering three modes of impressions. The data were statistically evaluated using two-way analysis of variance (ANOVA) for each site and the Bonferroni test., Results: there was no difference between the two kinds of impression in Group A in both sites, in Group B a difference of 0.483 mm and 0.682 mm at interproximal and buccal sites, respectively, and in Group C 0.750 mm and 0.964 mm at interproximal and buccal sites, respectively. The analysis performed on a site level (mesial/distal/vestibular) for the depth of both vertical preparations revealed significant differences ( p < 0.0001). After a post hoc analysis (Bonferroni), vestibular sites of the shallow vertical preparations resulted in significantly lower values compared to the other sites prepared deeply., Conclusions: the results showed that the location of the margin is an important factor in making a precise and complete impression when IOS (Intra Oral Scanner) is used. Moreover, deep preparation into the sulcus is not recommended for IOS (Intra Oral Scanner) impressions.

Statement of Problem: Intraoral scanners are promising options for removable prosthodontics. However, analog aids, including occlusion rims, are still used, as a completely digital workflow is challenging and scientific evidence on the topic is scarce., Purpose: The purpose of this in vitro study was to assess and compare the trueness and precision of scans obtained from a reference typodont of a completely edentulous maxilla by using an intraoral scanner (TRIOS 3 Pod; 3Shape A/S) with scans obtained by using a laboratory scanner (DScan 3; EGS S.R.L.) from both Type IV stone casts and polysulfide impressions., Material and Methods: The polyurethane resin reference typodont was replicated from a clinical cast and was scanned with a metrological machine to obtain a reference scan. Ten digital casts were obtained by applying standardized scanning strategies to the reference typodont with the intraoral scanner. A device was created to make 10 consistent polysulfide impressions, and a scan of each impression was made with the laboratory scanner and then digitally reversed to obtain 10 digital reversed casts. Ten Type IV stone casts were poured and then scanned with the laboratory scanner to obtain 10 digital extraoral scanner casts. The scans in standard tessellation language (STL) format were imported into a dedicated software program, and the trueness and precision were calculated in μm. In addition to descriptive statistics (confidence interval 95%), 1-way ANOVA followed by the Bonferroni test or the Kruskal-Wallis and the Dunn tests were used to analyze differences among groups (α=.05)., Results: The trueness values (95% confidence interval) were digital intraoral scanner cast=48.7 (37.8-59.5), digital reversed cast=249.9 (121.3-378.5), and digital extraoral scanner cast=308.8 (186.6-430.9); significant differences were detected between digital intraoral scanner cast and digital reversed cast (P<.001) and between digital IOS casts and digital extraoral scanner cast (P<.001). The precision values (95% confidence interval) were digital intraoral scanner cast=46.7 (29.7-63.7), digital reversed cast=271.2 (94.6-447.8), and digital extraoral scanner cast=341.4 (175.5-507.3); significant differences were detected between digital intraoral scanner cast and digital reversed cast (P=.003) and between digital intraoral scanner cast and digital extraoral scanner cast (P=.001)., Conclusions: Directly scanning a solid typodont of a completely edentulous maxilla with the intraoral scanner produced better trueness and precision than scanning the polysulfide impressions or the stone casts with a laboratory scanner., (Copyright © 2020 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Statement of Problem: Information about the accuracy of intraoral scanners for the edentulous maxilla is lacking., Purpose: The purpose of this in vitro study was to compare the accuracy of 3 different intraoral scanner techniques on a completely edentulous maxilla typodont., Material and Methods: Two completely edentulous maxillary typodonts with (wrinkled typodont) and without (smooth typodont) palatal rugae were used as reference and were scanned by using an industrial metrological machine to obtain 2 digital reference scans in standard tessellation language (STL) format (dWT and dST). Three different scanning techniques were investigated: in the buccopalatal technique, the buccal vestibule was scanned with a longitudinal movement ending on the palatal vault with a posteroanterior direction; the S-shaped technique was based on an alternate palatobuccal and buccopalatal scan along the ridge; in the palatobuccal technique, the palate was scanned with a circular movement and then with a longitudinal one along the buccal vestibule. Consecutively, 6 types of scans were obtained (n=10), namely wrinkled typodont/buccopalatal technique, wrinkled typodont/S-shaped technique, wrinkled typodont/palatobuccal technique (wrinkled typodont), smooth typodont/buccopalatal technique, smooth typodont/S-shaped technique, and smooth typodont/palatobuccal technique (smooth typodont). Scans in STL format were imported into a dedicated software program, and trueness and precision were evaluated in μm. In addition to descriptive statistics (95% confidence interval), a 2-factor ANOVA on the data ranks, the Kruskal-Wallis, and the Dunn tests were performed to analyze differences among groups (α=.05)., Results: Mean values for trueness (95% confidence interval) were wrinkled typodont/buccopalatal technique=48.7 (37.8-59.5); wrinkled typodont/S-shaped technique=65.9 (54.9-77.4); wrinkled typodont/palatobuccal technique=109.7 (96.1-123.4); smooth typodont/buccopalatal technique=48.1 (42.4-53.7); smooth typodont/S-shaped technique=56.4 (43.9-68.9); smooth typodont/palatobuccal technique=61.1 (53.3-69), with statistically significant differences for wrinkled typodont/buccopalatal technique versus wrinkled typodont/palatobuccal technique (P<.001), buccopalatal technique versus palatobuccal technique (P<.001), and wrinkled typodont versus smooth typodont (P=.002). Mean values for precision (95% confidence interval) were wrinkled typodont/buccopalatal technique=46.7 (29.7-63.7); wrinkled typodont/S-shaped technique=53.6 (37.6-69.7); wrinkled typodont/palatobuccal technique=90 (59.1-120.9); smooth typodont/buccopalatal technique=46 (39.7-52.3); smooth typodont/S-shaped technique=76 (55.5-96.6); smooth typodont/palatobuccal technique=52.9 (41.9-63.8); with statistically significant differences for buccopalatal technique versus palatobuccal technique (P=.032) and wrinkled typodont/buccopalatal technique versus wrinkled typodont/palatobuccal technique (P=.012)., Conclusions: Smooth typodont scans showed better trueness than wrinkled typodont scans. Buccopalatal technique showed better mean values for trueness and precision than palatobuccal technique only in the wrinkled typodont scenario, while the other scanning approaches did not show significant differences in either tested configuration., (Copyright © 2020 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Objectives: the purpose of the present prospective trial was to evaluate the clinical performance of posterior 3-unit zirconia-based fixed dental prostheses (FDPs) after 14 years of clinical function., Methods: thirty-seven patients needing to replace either premolars or molars were involved and 48 FDPs were fabricated (Procera Zirconia, Nobel Biocare AB). Frameworks with a9 mm 2 cross section of the connectors and 0.6 mm minimum thickness of the retainers were made by means of Procera Forte CAD-CAM System (Nobel Biocare AB). The patients were recalled after 6 and 12 months and then yearly up to a total follow-up of 14 years. Two independent survival curves for patients wearing 1 or 2 FDPs were calculated by means of Kaplan-Meier analysis and a log-rank test was performed in order to compare these curves. The United States Public Health Service criteria were used to examine technical and esthetic outcomes. The biological examination was performed evaluating plaque control, pocket depth, attachment level, bleeding on probing at both abutments and contralateral teeth and evaluated by means of the Wilcoxon test (p < 0.05) between the baseline and the 14-year follow-up., Results: descriptive statistics resulted in 91 % and 99 % cumulative survival rates for patients wearing 1 and 2 FDPs, respectively. There were no significant differences in periodontal parameters between control and test teeth. Both function and esthetic results were successful for FDPs over a 14-year follow-up period., Conclusions: the results of this prospective clinical study confirmed the effectiveness of zirconia as a clinical option to fabricate short-span posterior FDPs., Clinical Significance: within the limitations of the present prospective clinical study, zirconia-based three-unit fixed dental prostheses perform satisfactorily on long term, in posterior areas and in patients with standard biomechanical conditions., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background: This study was aimed at comparing the accuracy of impressions of a reference typodont (RT) reproducing a totally edentulous maxilla made with three impression materials: polysulfide, polyether, and polyvinyl-siloxane., Methods: The RT was scanned using a desktop scanner, obtaining a reference scan. Ten impressions for each of the three tested materials were made using a mechanical device with a standardized and consistent modality. A laboratory scanner performed the digitization of each impression. We produced digital models by processing "in reverse" the scans of the physical impressions using a dedicated software, obtaining three groups (n = 10), respectively. The groups were titled: "polysulfide," "polyvinyl-siloxane," and "polyether." The scans in .stl format were imported into Geomagic Control X and then compared to RT to evaluate the accuracy of each scan by calculating trueness and precision in µm. Recorded data were subjected to descriptive statistics., Results: Trueness (arithmetic proximity) values (95%CI) were: polysulfide = 249.9 (121.3-378.5), polyvinyl-siloxane = 216.8 (123.1-310.6), polyether = 291.1 (219.9-362.3). Precision values (95% CI) were: polysulfide = 261.9 (108.8-415), polyvinyl-siloxane = 209.4 (111.9-306.8), polyether = 283 (227.9-338.1). Statistically significant differences were not detected between the means of the experimental groups, both for trueness and precision., Conclusions: The accuracy of the scans obtained from polyvinyl-siloxane, polysulfide, and polyether impressions can be considered comparable in a fully edentulous maxilla., Competing Interests: The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

Purpose: To evaluate the biomechanical behavior of monolithic ceramic crowns with functional elasticity gradient., Methods: Using a CAD software, a lower molar received a full-crown preparation (1.5 mm occlusal and axial reduction). The monolithic crown was modeled with a resin cement layer of 0.1 mm. Four groups were distributed according to the full crown elastic modulus (E) :(a) Bioinspired crown with decreasing elastic modulus (from 90 to 30GPa); (b) Crown with increasing elastic modulus (from 30 to 90 GPa); (c) Rigid crown (90 GPa) and (d) Flexible crown (30 GPa). The model was exported to the analysis software and meshed into 385.240 tetrahedral elements and 696.310 nodes. Materials were considered isotropic, linearly elastic, and homogeneous, with ideal contacts. A 300-N load was applied at the occlusal surface and the base of the model was fixed in all directions. The results were required in maximum principal stress criterion., Results: Crowns consisting of layers with increasing elastic modulus presented intermediate results between the rigid and flexible crowns. Compared to the flexible crown, the bioinspired crown showed acceptable stress distribution across the structure with lower stress concentration in the tooth. In dental crowns the multilayer structure with functional elasticity gradient modifies the stress distribution in the restoration, with promising results for bioinspired design., Clinical Significance: The manufacturing of posterior crowns with functional elasticity gradient should be considered due to its promising results on the stress concentration behavior., Competing Interests: The authors declared they had no conflict of interest. The study was supported by the São Paulo Research Foundation (FAPESP) with the grant no. 18/05736-9., (Copyright©American Journal of Dentistry.)

Background: The introduction of the new generation of particle-filled and high strength ceramics, hybrid composites and technopolymers in the last decade has offered an extensive palette of dental materials broadening the clinical indications in fixed prosthodontics, in the light of minimally invasive dentistry dictates. Moreover, last years have seen a dramatic increase in the patients' demand for non-metallic materials, sometimes induced by metal-phobia or alleged allergies. Therefore, the attention of scientific research has been progressively focusing on such materials, particularly on lithium disilicate and zirconia, in order to shed light on properties, indications and limitations of the new protagonists of the prosthetic scene., Methods: This article is aimed at providing a narrative review regarding the state-of-the-art in the field of these popular ceramic materials, as to their physical-chemical, mechanical and optical properties, as well as to the proper dental applications, by means of scientific literature analysis and with reference to the authors' clinical experience., Results: A huge amount of data, sometimes conflicting, is available today. Both in vitro and in vivo studies pointed out the outstanding peculiarities of lithium disilicate and zirconia: unparalleled optical and esthetic properties, together with high biocompatibility, high mechanical resistance, reduced thickness and favorable wear behavior have been increasingly orientating the clinicians' choice toward such ceramics., Conclusions: The noticeable properties and versatility make lithium disilicate and zirconia materials of choice for modern prosthetic dentistry, requiring high esthetic and mechanical performances combined with a minimal invasive approach, so that the utilization of such metal-free ceramics has become more and more widespread over time.

Objectives: The objective of this randomized controlled trial was to assess the influence of use of posts as well as the type of posterior tooth (premolars vs molars) for the treatment with lithium disilicate (LS2) partial crowns., Materials and Methods: A total of 60 patients were treated with posterior LS2 partial crowns. Two groups (n = 60) were made based on the type of restored tooth: Group 1, premolars and Group 2, molars. The samples of each group were divided into 2 subgroups (n = 30): Subgroup A restored with fiber posts and Subgroup B without them. Clinical and intraoral radiographic examinations were assessed during each recall (6 months and, 1, 2, and 3 years). Kaplan-Meier log-rank test and Cox regression analysis (Pp < 0.05) were applied., Results: Three subgroups showed 100% of survival while group 2 A exhibited the lowest performance (93.3%). The Cox regression analysis showed that the presence of the post was not a significant factor for survival time (Hazard Ratio HR = 0388; CI95% Confidence Interval for H R = 0,1- to 1,5; pp = 017). Tooth type had an influence on survival time that was at the limit of statistical significance (Hazard Ratio HR = 0123; CI95% Confidence Interval for HR = 0 0015- to 0997; p = 005). Particularly, failure risk was greater for premolars. 'Post by tooth type' interactions were not statistically significant (p = 0126)., Conclusions: over a 3-year observation period, the clinical performance of endodontically treated teeth restored with lithium disilicate partial crowns was not significantly affected by the use of a fiber post and by the type of tooth (premolars or molars)., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Objectives: Stresses produced during the fabrication of copings and by chewing activity can induce a tetragonal-to-monoclinic (t⁻m) transformation of zirconia. As a consequence, in the m-phase, the material is not able to hinder possible cracks by the favorable mechanism known as "transformation toughening". This study aimed at evaluating if different marginal preparations of zirconia copings can cause a premature phase transformation immediately after manufacturing milling and after chewing simulation., Methods: Ninety copings using three commercial zirconia ceramics (Nobel Procera Zirconia, Nobel Biocare Management AG; Lava Classic, 3M ESPE; Lava Plus, 3M ESPE) were prepared with deep-chamfer, slight-chamfer, or feather-edge finish lines (n = 10). Specimens were tested in a chewing simulator (CS-4.4, SD Mechatronik) under cyclic occlusal loads simulating one year of clinical service. Raman spectra were acquired and analyzed for each specimen along the finish lines and at the top of each coping before and after chewing simulation, respectively., Results: Raman analysis did not show any t⁻m transformation both before and after chewing simulation, as the typical monoclinic bands at 181 cm -1 and 192 cm -1 were not detected in any of the tested specimens., Conclusions: After a one-year simulation of chewing activity, irrespective of preparation geometry, zirconia copings did not show any sign of t⁻m transformation, either in the load application areas or at the margins. Consequently, manufacturing milling even in thin thickness did not cause any structural modification of zirconia ceramics "as received by manufacturers" both before and after chewing simulation., Competing Interests: The authors declare no conflicts of interest.

Objectives: The aim of this study was to validate the reproducibility and observer variability of the Functional Implant Prosthodontic Score (FIPS), while considering the level of dental experience for intra- and inter-examiner analysis., Materials and Methods: A total of 44 examiners (n = 31 undergraduate dental students and n = 13 postgraduate prosthodontic students) applied FIPS to ten sample cases each showing one implant-supported single crown for premolar or molar replacements. Examiners' assessments were carried out twice at an interval of 2 weeks (round A and round B). Pearson's correlations including 95% confidence intervals (CI95) were calculated for intra- and inter-examiner reproducibility testing. Cohen's Kappa score was additionally used to analyze the homogeneity of each FIPS variable., Results: The mean values of the total FIPS scores for round A (7.21 ± 0.91) and round B (7.27 ± 0.86) showed a strong correlation of 0.9374 (CI95 0.9250; 0.9478). No significant difference was identified between undergraduates and postgraduates representing different levels of dental experience. Homogeneity analysis of the defined FIPS variables was not significantly different., Conclusions: Both intra- and inter-examiner analysis revealed very congruent results for reproducibility testing of FIPS. The findings validated the potential of FIPS as an objective and reliable evaluation instrument in assessing fixed implant restorations in posterior sites independent of the level of dental experience., Clinical Relevance: FIPS can be considered as an additional diagnostic tool to classify fixed implant restorations in routine dental practice, to compare follow-up observations, and to identify potential risks of failure.

Objectives: The dental market moves towards high-translucency monolithic zirconia dental crowns, which are usually placed either with - or without - a thin glaze layer. The microstructural features and the mechanical performances of these materials are still controversial, as well as their susceptibility to aging. This paper aims at studying these aspects in the current generation of zirconia dental crowns showing different degrees of translucency., Methods: Four different commercial zirconia materials were investigated, including one standard 'full-strength' 3Y-TZP and three grades with improved translucency. The microstructural features (phase composition and assemblage, grain size) were carefully studied, as well as mechanical properties (biaxial bending strength and indentation toughness), translucency and aging behavior (in autoclave at 134°C). Aging was conducted on crowns with and without glaze to better represent clinical uses., Results: Important differences are found in terms of microstructures among the materials in terms of cubic phase content and yttria in the tetragonal phase, leading to different optical, mechanical and aging resistance properties. We show that higher cubic phase content leads to better translucency and stability in water steam, but at the expense of strength and toughness. A compromise is always inevitable between translucency and aging resistance on one side and mechanical properties on the other side., (Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.)

Objective: To assess the effect of a ferrule design with specific post material-shape combinations on the mechanical behavior of post-restored canine teeth., Methods: Micro-CT scan images of an intact canine were used to create a 3-D tessellated CAD model, from which the shapes of dentin, pulp and enamel were obtained and geometric models of post-endodontically restored teeth were created. Two types of 15mm post were evaluated: a quartz fiber post with conical-tapered shape, and a carbon (C) fiber post with conical-cylindrical shape. The abutment was created around the coronal portion of the posts and 0.1mm cement was added between prepared crown and abutment. Cement was also added between the post and root canal and a 0.25mm periodontal ligament was modeled around the root. Four models were analysed by Finite Element (FE) Analysis: with/without a ferrule for both types of post material and shape. A load of 50N was applied at 45° to the longitudinal axis of the tooth, acting on the palatal surface of the crown. The maximum normal stress criterion was adopted as a measure of potential damage., Results: Models without a ferrule showed greater stresses (16.3MPa) than those for models with a ferrule (9.2MPa). With a ferrule, stress was uniformly distributed along the abutment and the root, with no critical stress concentration. In all models, the highest stresses were in the palatal wall of the root. Models with the C-fiber post had higher stress than models with the quartz fiber posts. The most uniform stress distribution was with the combination of ferrule and quartz fiber post., Significance: The FE analysis confirmed a beneficial ferrule effect with the combination of ferrule and quartz fiber post, with tapered shape, affording no critical stress concentrations within the restored system., (Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.)

Background: The continuous development in dental processing ensures new opportunities in the field of fixed prosthodontics in a complete virtual environment without any physical model situations. The aim was to compare fully digitalized workflows to conventional and/or mixed analog-digital workflows for the treatment with tooth-borne or implant-supported fixed reconstructions., Methods: A PICO strategy was executed using an electronic (MEDLINE, EMBASE, Google Scholar) plus manual search up to 2016-09-16 focusing on RCTs investigating complete digital workflows in fixed prosthodontics with regard to economics or esthetics or patient-centered outcomes with or without follow-up or survival/success rate analysis as well as complication assessment of at least 1 year under function. The search strategy was assembled from MeSH-Terms and unspecific free-text words: {(("Dental Prosthesis" [MeSH]) OR ("Crowns" [MeSH]) OR ("Dental Prosthesis, Implant-Supported" [MeSH])) OR ((crown) OR (fixed dental prosthesis) OR (fixed reconstruction) OR (dental bridge) OR (implant crown) OR (implant prosthesis) OR (implant restoration) OR (implant reconstruction))} AND {("Computer-Aided Design" [MeSH]) OR ((digital workflow) OR (digital technology) OR (computerized dentistry) OR (intraoral scan) OR (digital impression) OR (scanbody) OR (virtual design) OR (digital design) OR (cad/cam) OR (rapid prototyping) OR (monolithic) OR (full-contour))} AND {("Dental Technology" [MeSH) OR ((conventional workflow) OR (lost-wax-technique) OR (porcelain-fused-to-metal) OR (PFM) OR (implant impression) OR (hand-layering) OR (veneering) OR (framework))} AND {(("Study, Feasibility" [MeSH]) OR ("Survival" [MeSH]) OR ("Success" [MeSH]) OR ("Economics" [MeSH]) OR ("Costs, Cost Analysis" [MeSH]) OR ("Esthetics, Dental" [MeSH]) OR ("Patient Satisfaction" [MeSH])) OR ((feasibility) OR (efficiency) OR (patient-centered outcome))}. Assessment of risk of bias in selected studies was done at a 'trial level' including random sequence generation, allocation concealment, blinding, completeness of outcome data, selective reporting, and other bias using the Cochrane Collaboration tool. A judgment of risk of bias was assigned if one or more key domains had a high or unclear risk of bias. An official registration of the systematic review was not performed., Results: The systematic search identified 67 titles, 32 abstracts thereof were screened, and subsequently, three full-texts included for data extraction. Analysed RCTs were heterogeneous without follow-up. One study demonstrated that fully digitally produced dental crowns revealed the feasibility of the process itself; however, the marginal precision was lower for lithium disilicate (LS2) restorations (113.8 μm) compared to conventional metal-ceramic (92.4 μm) and zirconium dioxide (ZrO2) crowns (68.5 μm) (p < 0.05). Another study showed that leucite-reinforced glass ceramic crowns were esthetically favoured by the patients (8/2 crowns) and clinicians (7/3 crowns) (p < 0.05). The third study investigated implant crowns. The complete digital workflow was more than twofold faster (75.3 min) in comparison to the mixed analog-digital workflow (156.6 min) (p < 0.05). No RCTs could be found investigating multi-unit fixed dental prostheses (FDP)., Conclusions: The number of RCTs testing complete digital workflows in fixed prosthodontics is low. Scientifically proven recommendations for clinical routine cannot be given at this time. Research with high-quality trials seems to be slower than the industrial progress of available digital applications. Future research with well-designed RCTs including follow-up observation is compellingly necessary in the field of complete digital processing.

Studies have failed to identify the molecular mechanisms that regulate the genotoxic and cytotoxic effects of methacrylate resins, which are important in the biocompatibility of dental materials. Interleukin (IL)-6 has a crucial role in the control of acute-phase protein response during inflammation. In humans, the synthesis and release of two major acute-phase proteins, C-reactive protein and serum amyloid A, are regulated by IL-6. This study focused on IL-6 and activation of its receptors gp80 and gp130 in human gingival fibroblasts in order to assess the effects of the commercial acid resins Jet Kit, Unifast, and Duralay on control of inflammation.

Today, innovative restorative materials and techniques allow for minimally invasive prosthetic procedures, which are paramount to the preservation of hard and soft dental tissues. An integrated approach combining dental and esthetic medical therapies could be useful to improve the quality of life of patients, improving function, esthetics, and self-confidence. Oral esthetics depends on several variables, including tooth visibility and proportions as well as healthy gingival tissues. Proper integration between teeth and periodontal tissues plays an important role in esthetic success, which is mainly represented by an appealing smile. The present case report was aimed at describing the multidisciplinary treatment of a woman who was unsatisfied with the shape of her central incisors and the dark gingival pigmentation displayed by a high smile line. The patient was treated with minimally invasive combined periodontal, prosthetic, and esthetic medical techniques. The described multidisciplinary approach based on surgical gingival depigmentation, adhesive ceramic veneers, and selective botulinum toxin injection was effective in solving the undesired high smile line and achieving patient satisfaction.

This multicenter retrospective clinical study aimed to evaluate the clinical performance of zirconia abutments in anterior and posterior regions, focusing on implant-abutment connections and restoration vertical height (RVH). Six experienced prosthodontists used 965 computer-aided design/computer-assisted manufacture zirconia abutments in 601 patients. Different surgical approaches were taken according to the needs of each patient. The final restorations were all-ceramic single crowns and short-span fixed dental prostheses. Screw-retained restorations were mainly used in anterior areas, whereas cemented prostheses were chosen in cases where the implant position was not ideal. Different types of implant-abutment connections were compared: external, internal with metal components, and internal full-zirconia conical connection. All the restorations were followed up for 4 to 10 years. Technical and biologic complications were assessed in relation to several biomechanical variables, such as RVH. Differences between groups were statistically analyzed, and longevity of abutments was evaluated according to Kaplan-Meier survival analysis. Zirconia abutments resulted in overall survival and success rates of 98.9% and 94.8%, respectively. External connections reported survival and success rates of 99.7% and 94.5%, internal metal connections 99.8% and 95.5%, and internal zirconia connections 93.1% and 93.1%, respectively. Overall complication rates of 1.14%, 3.42%, and 0.62% were reported for fractures, chipping, and unscrewing, respectively. The external connection showed the longest survival while the internal zirconia connection showed the highest fracture incidence over the observation period. The clinical risk limit of RVH was identified as 14 mm. Zirconia abutments showed satisfactory clinical performance in anterior and posterior regions after 4 to 10 years. RVH and connection type influenced the clinical longevity of restorations; in particular, internal connections with secondary metallic components reduced the incidence of complications.

Background: Zirconia abutments were introduced to restore esthetic regions and showed sufficient stability to support implant restorations. Nonetheless, to date the observation periods are shorter than those of titanium abutments., Purpose: To assess the survival of implant crowns supported by computer aided design-computer aided manufacturing (CAD-CAM) abutments after 3 years., Materials and Methods: Fifty-six patients were selected for this prospective clinical study. Each patient received at least 1 titanium implant for a total of 89 fixtures. A two-stage surgical technique and no additional soft or hard tissue graft were used. The implants were randomly divided into 3 groups receiving different CAD-CAM abutments: titanium, titanium nitride, and zirconia. Zirconia or metal-ceramic crowns were used as final restorations. Cementation was the baseline and the restorations were checked after 6 months, 1, 2, and 3 years, assessing any mechanical complication. Statistical analyses were performed to evaluate the 3-year success rates., Results: Five failures were reported in the zirconia group; all the failed restorations showed fractures of the abutment connection. Four failures occurred in posterior regions and one more occurred while screwing the abutment. Titanium and titanium nitride abutments had significantly higher 3-year success rates than zirconia abutments (p < .05)., Conclusions: Atlantis titanium and titanium nitride abutments showed optimal clinical performances after 3 years. Conversely, Atlantis zirconia abutments should be avoided to restore posterior regions., (© 2016 Wiley Periodicals, Inc.)

Objective: The present systematic review aimed at assessing data from the literature on endodontic and prosthetic complications in endodontically treated teeth restored with fiber posts and single crowns (SCs) or fixed dental prostheses (FDPs)., Materials and Methods: Available randomized controlled clinical trials evaluating endodontic and prosthetic complications in the teeth treated with fiber posts and restored with different prosthetic restorations were reviewed. PubMed, Evidence-Based Dentistry, BMJ Clinical Evidence, Embase, DynaMed, and gray literature restricted to scientific literature were analyzed; also, manual researches were performed. English language and time filters (from 1990 to 2015) were used., Results: The database search produced 4230 records, many of which were duplicates. The manual research did not produce any other relevant article. After duplications were removed, all the selected databases produced 3670 records. Reading titles and abstracts, two independent reviewers excluded 3664 reports. The full-texts of the remaining six reports were read. Only four studies met the inclusion criteria and were included in this systematic review., Conclusions: The most frequently reported failures in the available studies were as follows: fiber post debonding, loss of retention of single crowns, and marginal gaps. Less frequently, chippings and fractures were recorded in SCs. No studies about complications related to FDPs were found., Clinical Relevance: A correlation between the failure rates of fiber posts and the type of prosthetic restorations just like SCs and FDPs cannot be found to date. Further randomized controlled clinical studies are required to achieve evidence-based conclusions, particularly about the use of fiber posts with FDPs.

Objectives: To present a practical approach that combines biomechanical tests, microcomputed tomography (μCT) and histomorphometry, providing quantitative results on bone structure and mechanical properties in a minipig model, in order to investigate the specific response to an innovative dental biomaterial., Methods: Titanium implants with innovative three-dimensional scaffolds were inserted in the tibias of 4 minipigs. Primary stability and osseointegration were investigated by means of insertion torque (IT) values, resonance frequency analysis (RFA), bone-to-implant contact (BIC), bone mineral density (BMD) and stereological measures of trabecular bone., Results: A significant positive correlation was found between IT and RFA (r=0.980, p=0.0001). BMD at the implant sites was 18% less than the reference values (p=0.0156). Peri-implant Tb.Th was 50% higher, while Tb.N was 50% lower than the reference zone (p<0.003) and they were negatively correlated (r=-0.897, p=0.006)., Significance: μCT increases evaluation throughput and offers the possibility for qualitative three-dimensional recording of the bone-implant system as well as for non-destructive evaluation of bone architecture and mineral density, in combination with conventional analysis methods. The proposed multimodal approach allows to improve accuracy and reproducibility for peri-implant bone measurements and could support future investigations., (Copyright © 2016 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.)

The aim of this retrospective clinical trial was to evaluate the performance of 91 turned implants placed in vertically augmented ridges in 33 patients by means of guided bone regeneration techniques after a mean follow-up of 15 years. A total of 88 implants were in function (97% survival rate), whereas 9 showed peri-implantitis (9.9%). A mean radiographic bone loss of 1.02 mm between the baseline evaluation (1 year after loading) and the final visit (13 to 21 years later) was recorded. In conclusion, turned implants placed in vertically augmented bone seem to remain stable after many years of function.

The present paper was aimed at reporting the state of the art about lithium disilicate ceramics. The physical, mechanical, and optical properties of this material were reviewed as well as the manufacturing processes, the results of in vitro and in vivo investigations related to survival and success rates over time, and hints for the clinical indications in the light of the latest literature data. Due to excellent optical properties, high mechanical resistance, restorative versatility, and different manufacturing techniques, lithium disilicate can be considered to date one of the most promising dental materials in Digital Dentistry.

Aim: The aim of the present microleakage study was to assess the sealing ability of nanohybrid composite crowns with different finish lines exposed to simulated mechanical periodontal treatment (SMPT)., Methods: After sample size calculation (α=0.05; β=0.20; δ=1.0; σ=0.8), sixty extracted mandibular molars were divided into four groups (N.=15): G1, 90° shoulder; G2, beveled 90° shoulder; G3, 90° shoulder and SMPT; G4, beveled 90° shoulder and SMPT. Tooth preparations were carried out by means of diamond burs and Arkansas stones. The buildup of crowns was performed with a nanohybrid composite on master casts obtained after polyether impressions and crowns were cemented with self-adhesive cement. Groups G3 and G4 were subjected to the equivalent of five years of semestral mechanical periodontal scaling with Gracey curettes (2-mm long strokes, 5 N). Samples were immersed into a methylene blue supersaturated solution for 10 minutes. Microleakage was measured by stereomicroscopic observation of multiple sections of the samples and leakage data underwent statistical analysis with non-parametric tests., Results: Marginal microleakage was 1.53±1.27% and 17.60±12.72% of the length of the adhesive interface in G1 and G2, respectively. SMPT reduced dye penetration (P<0.001) with G3 not leaking at all and G4 leaking along the 5.58±1.84% of the adhesive interface. The bevel preparation significantly worsened the marginal seal both in control and treated crowns (P<0.001)., Conclusion: Microleakage of nanohybrid composite crowns increased by adding a bevel to a 90° shoulder preparation and diminished after SMPT.

Purpose: The present prospective clinical study evaluated the influence of coping design on the fracture resistance of CAD/CAM zirconia single crowns layered with dedicated ceramics., Methods: 56 subjects were provided with 90 zirconia single crowns in posterior regions. Tooth preparations were standardized and the abutment teeth were randomly distributed into three groups, according to three different coping designs (flat design, FD; porcelain-fused-to-metal-like crowns, PFM; anatomically-guided, AG). The zirconia cores were produced using a CAD/CAM software and then were hand-layered with dedicated ceramics. All crowns were cemented with a self-adhesive resin luting agent and the patients were recalled for follow-up visits after 1 month, 6 months, 1, 2 and 3 years of clinical service. The function, esthetics and marginal adaptation of the restorations were evaluated. Statistical analyses were performed to evaluate survival and success of the restorations., Results: Success rates of 100% were reported in Group 2 and Group 3 while the percentage was 80% in Group 1. Three chippings were noticed in Group 1 (FD) and two crowns needed to be replaced after 3 years, resulting in a survival rate of 93.3%. Group 2 and Group 3 had significantly higher 3-year success rates than Group 1 (P < 0.05). Based on the present clinical results, the following conclusions were drawn: the porcelain-fused-to-metal-like and the anatomically-guided frameworks for zirconia single crowns performed better clinically than the flat designed cores in posterior regions after 3 years; standardized tooth preparations achieved even thicknesses of the bilayered restorations; the proper support given to the veneering ceramic by the correct design of the zirconia framework could significantly reduce the risk of chipping during function.

Due to the brittleness and limited tensile strength of the veneering glass-ceramic materials, the methods that combine strong core material (as zirconia or alumina) are still under debate. The present study aims to evaluate the fracture strength and the mechanism of failure through fractographic analysis of single all-ceramic crowns supported by implants. Forty premolar cores were fabricated with CAD/CAM technology using alumina (n = 20) and zirconia (n = 20). The specimens were veneered with glass-ceramic, cemented on titanium abutments, and subjected to loading test until fracture. SEM fractographic analysis was also performed. The fracture load was 1165 (±509) N for alumina and 1638 (±662) N for zirconia with a statistically significant difference between the two groups (P = 0.026). Fractographic analysis of alumina-glass-ceramic crowns, showed the presence of catastrophic cracks through the entire thickness of the alumina core; for the zirconia-glass-ceramic crowns, the cracks involved mainly the thickness of the ceramic veneering layer. The sandblast procedure of the zirconia core influenced crack path deflection. Few samples (n = 3) showed limited microcracks of the zirconia core. Zirconia showed a significantly higher fracture strength value in implant-supported restorations, indicating the role played by the high resistant cores for premolar crowns.

In last years the use of zirconia in dentistry has become very popular. Unfortunately, the clinical indications for a dental use of zirconia are not completely clear yet, neither are their limitations. The objective of this review was to evaluate the basic science knowledge on zirconia and to discuss some aspects of the clinical behavior of zirconia-based restorations. In particular, one of the goals was highlighting the possible correlation between in vitro and in vivo studies. The definition of concepts like success, survival and failure was still debated and the correlation between in vitro results and predictability of clinical behavior was investigated., (Published by Elsevier Ltd.)

The objective of this study was to evaluate the residual dentin thickness (RDT) after different tooth preparations. Ninety mandibular anterior teeth were divided into three groups: central incisors, lateral incisors, and canines. Specimens were prepared for single-crown coverage with shoulder, slight chamfer, and knife-edge finish lines. Specimens were sectioned and divided into four subgroups according to measurement areas: (1) buccal, (2) distal, (3) lingual, and (4) mesial. The RDT was analyzed statistically by means of one-way analysis of variance and Tukey post hoc test (P = .05). Significant differences were found for shoulder but not for slight chamfer and knife-edge finish lines. The interproximal areas wound up being critical due to thin RDT, potentially interfering with the structural and biologic integrity of teeth.

Purpose: Implant impressions and working models form integrated precision systems for registration and transmission of clinical data. The components of implant systems have a dimensional tolerance capable of introducing inaccuracies in the impression, thus in the prosthetic framework. This article aimed at comparing 2 repositioning impression techniques: one using impression copings (conventional technique) and the other using the final abutments as impression copings (interceptive technique)., Materials and Methods: Two experimental models, one with 4 parallel implants and the other with 4 nonparallel implants, were used to make silicone impressions. Twenty impressions were made with the conventional technique, and a further 20 were made with the interceptive technique. Three-dimensional images acquired with a three-dimensional scanner were measured using a three-dimensional image analysis software, comparing models obtained from the impressions with the experimental models. Data were statistically analyzed by means of confidence intervals calculated with the mean (α = 0.05), descriptive (box plot), and bivariate analyses., Results: Statistic analysis highlighted significant differences among models obtained using both techniques: the interceptive technique generated working models with less distortion and variability., Conclusions: For internal-connection implants, the interceptive technique provided significantly more precise working models than did the conventional technique.

This study aimed to assess the clinical performance of lithium disilicate restorations supported by natural teeth or implants. Eight hundred sixty lithium disilicate adhesive restorations, including crowns on natural teeth and implant abutments, veneers, and onlays, were made in 312 patients. Parafunctional patients were included, but subjects with uncontrolled periodontitis and gingival inflammation were excluded. Veneers up to 0.5 mm thick were luted with flowable composite resin or light curing cements, while dual-curing composite systems were used with veneers up to 0.8 mm thick. Onlays up to 2 mm in thickness were luted with flowable composite resins or dual-curing composite cements. Crowns up to 1 mm in thickness were cemented with self-adhesive or dual-curing resin cements. The observational period ranged from 12 to 72 months, with a mean follow-up of 3 years. The mechanical and esthetic outcomes of the restorations were evaluated according to the modified California Dental Association (CDA) criteria. Data were analyzed with descriptive statistics. Twenty-six mechanical complications were observed: 17 porcelain chippings, 5 fractures, and 4 losses of retention. Structural drawbacks occurred mainly in posterior segments, and monolithic restorations showed the lowest number of mechanical complications. The clinical ratings of the successful restorations, both monolithic and layered, were satisfactory according to the modified CDA criteria for color match, porcelain surface, and marginal integrity. The cumulative survival rates of lithium disilicate restorations ranged from 95.46% to 100%, while cumulative success rates ranged from 95.39% to 100%. All restorations recorded very high survival and success rates. The use of lithium disilicate restorations in fixed prosthodontics proved to be effective and reliable in the short- and medium-term.

Aim: To evaluate the growth of Human Gingival Fibroblasts (HGFs) cultured onto sample discs of CAD/CAM zirconia and veneering ceramic for zirconia by means of Scanning Electron Microscope (SEM) analysis at different experimental times., Methods: A total of 26 experimental discs, divided into 2 groups, were used: Group A) CAD/CAM zirconia (3Y-TZP) discs (n=13); Group B) veneering ceramic for zirconia discs (n=13). HGFs were obtained from human gingival biopsies, isolated and placed in culture plates. Subsequently, cells were seeded on experimental discs at 7,5×10(3)/cm(2) concentration and cultured for a total of 7 days. Discs were processed for SEM observation at 3h, 24h, 72h and 7 days., Results: In Group A, after 3h, HGFs were adherent to the surface and showed a flattened profile. The disc surface covered by HGFs resulted to be wider in Group A than in Group B samples. At SEM observation, after 24h and 72h, differences in cell attachment were slightly noticeable between the groups, with an evident flattening of HGFs on both surfaces. All differences between Group A and group B became less significant after 7 days of culture in vitro., Conclusions: SEM analysis of HGFs showed differences in terms of cell adhesion and proliferation, especially in the early hours of culture. Results showed a better adhesion and cell growth in Group A than in Group B, especially up to 72h in vitro. Differences decreased after 7 days, probably because of the rougher surface of CAD/CAM zirconia, promoting better cell adhesion, compared to the smoother surface of veneering ceramic.

Human gingival fibroblasts (HGFs) were cultured onto CAD/CAM zirconia (Group A), CAD/CAM zirconia after polishing (Group B), CAD/CAM lithium disilicate after polishing (Group C), and feldspathic ceramic (Group D) to evaluate their proliferation and adhesion potential. After 3 h, HGF adhesion was similar in all groups. Later, HGFs closely adhered to surfaces, particularly onto groups B, C and D, acquiring an elongated shape. Proliferation assay showed no differences in cell viability among the groups after 24 h, while significant increase was shown after 72 h in Groups B and C. After 24 h, similar Collagen I levels were found in all groups, while after 72 h Groups B and C revealed a deep reduction in respect to the 24 h level. In vitro, HGF behavior may reflect variability in soft tissue response to different surface materials for prosthetic restorations, and support that polished zirconia is able to achieve a better integration in vivo in respect to the other materials.

To evaluate residual dentin thickness (RDT) after different tooth preparations, 90 sound maxillary anterior teeth were selected and divided into 3 groups according to tooth type (n = 30), namely, maxillary central incisors, maxillary lateral incisors, and maxillary canines. In each group, specimens were randomly divided and prepared for single-crown coverage with shoulder (SHO, n = 10, control), slight chamfer (CHA, n = 10), and knife-edge (KNE, n = 10) finish lines. After tooth preparation, specimens were sectioned and divided into 4 subgroups (buccal, distal, palatal, and mesial) according to measurement area. RDT values were compared by using one-way ANOVA and Tukey's post hoc test (P = 0.05). Significant differences were found between SHO and the other two groups (P < 0.05) but not between CHA and KNE (P > 0.05). SHO was significantly more aggressive than CHA and KNE, which were comparable. Interproximal areas became critical due to thin RDT, which could potentially compromise the structural and biological integrity of teeth. The choice of finish line should be guided by careful clinical evaluation.

The present in vitro study aimed to assess the effects of root surface mechanical instrumentation on the marginal integrity and adaptation of resin composite crowns. The following null hypotheses were tested: no differences exist between finish line and 1) marginal gap or 2) marginal microleakage before and after manual mechanical periodontal maintenance. A total of 56 intact human mandibular molars were randomly distributed into four groups and subjected to standardized tooth preparations for indirect composite crowns with different marginal finish lines (90° shoulder, beveled 90° shoulder, feather edge, chamfer). One-half of the specimens was used as a control and remained untreated, and the remaining half was subjected to root surface procedures simulating five years of semestral mechanical supportive periodontal treatment. The marginal gap and microleakage were evaluated and statistically analyzed. The specimens used as controls showed lower mean marginal gaps than those subjected to the simulated periodontal treatment, whereas the latter showed lower microleakage than the control crowns. Statistically significant differences were recorded for both the experimental variables. The root surface procedures resulted in altered surfaces of the composite crowns. The marginal gap increased after the treatment, whereas the marginal microleakage was reduced. The 90° shoulder and the chamfer preparation could be considered a viable option to fabricate composite crowns, but the beveled 90° shoulder and the feather edge should not be recommended.

Aim: The aim of this study was to investigate the retention values and mode of failure of metal crowns and fibre-reinforced composite crowns., Methods: Seventy-five implants and the corresponding abutments were used. After the galvanic copings were fabricated, the specimens were distributed into three groups: in group A traditional metal crowns were realized, whereas in groups B and C fibre-reinforced composite crowns were made. In group B the same resin based cement used in group A was employed for luting the fibre-reinforced composite crowns to the galvanic copings, while in group C a dedicated self-adhesive composite cement was used. All galvanic coping/crown assemblies were cemented onto abutments with Panavia 21 cement. Specimens were subjected to a pull-out test; median retentive values and standard deviations were calculated., Results: All samples in the group A showed separation at the abutment-galvanic cap interface. All samples in the group B showed decementation at galvanic cap-crown interface. In 13 samples of the group C the decementation occurred at the abutment-galvanic cap interface and in 12 samples of this group the decementation occurred at the galvanic cap-crown interface. The mean retention value was 659.1 N±162.9 for group A, 304.7 N±101.4 for B and 635.4 N±155.9 for C. Differences between groups A/B and B/C are statistically significant (t-student test, P<0.01), while is not statistically different between groups A/C., Conclusion: When a self-adhesive composite cement is used, fibre-reinforced composite single crowns and conventional metal crowns show similar retentive performance.

This prospective clinical trial aimed at evaluating the clinical performance of three-unit posterior zirconia fixed dental prostheses (FDPs) after 5 years of clinical function. Thirty-seven patients received 48 three-unit zirconia-based FDPs. The restorations replaced either a premolar or a molar. Specific inclusion criteria were needed. Tooth preparation was standardized. Computer-aided design/computer-assisted manufacturing frameworks with a 9-mm(2) cross section of the connector and a 0.6-mm minimum thickness of the retainer were made. The restorations were luted with resin cement. The patients were recalled after 1, 6, 12, 24, 36, 48, and 60 months. The survival and success of the ceramics and zirconia were evaluated. The technical and aesthetic outcomes were examined using the United States Public Health Service criteria. The biologic outcomes were analyzed at abutment and contralateral teeth. Descriptive statistics were performed. All FDPs completed the study, resulting in 100% cumulative survival rate and 91.9% and 95.4% cumulative success rates for patients wearing one and two FDPs, respectively. No losses of retention were recorded. Forty-two restorations were rated alpha in all measured parameters. A minor chipping of the ceramics was detected in three restorations. No significant differences between the periodontal parameters of the test and control teeth were observed. Five-year clinical results proved that three-unit posterior zirconia-based FDPs were successful in the medium term for both function and aesthetic. Zirconia can be considered a promising substitute of metal frameworks for the fabrication of short-span posterior prostheses.

Purpose: To evaluate the influence of post length insertion on the fracture resistance of directly restored endodontically treated teeth., Methods: 30 maxillary central incisors were restored with glass fiber posts and composite cores to produce groups with post lengths of (1) 5 mm, (2) 7 mm, and (3) 9 m. Specimens were loaded at 130 degrees (Instron). Fracture strengths were analyzed with the Kolmogorov-Smirnov Test to verify the normality of the data distribution and with ANOVA and Tukey's post hoc test at P < 0.05. Fracture patterns (restorable or unrestorable) were analyzed (Pearson's Chi-square test)., Results: The average fracture resistance was: Group 1 = 366.4 N, Group 2 = 507.4 N and Group 3 = 509.9 N. No significant difference was found among the three groups for fracture resistance or for failure mode. The insertion length did not influence the fracture pattern; more restorable fractures were detected.

Background: The Procera AllCeram™ system (Nobel Biocare AB, Göteborg, Sweden) is a valid alternative to metal-ceramic restorations. However, limited long-term data of its use for single crowns on natural and implant-supported abutments are available., Purpose: The present study aimed at evaluating the clinical performances of Procera AllCeram single crowns in both anterior and posterior regions of the oral cavity either on natural tooth or implant abutments over a period of 6 years., Materials and Methods: Two hundred nine single crowns were fabricated and used in 112 patients. Zinc phosphate and resin luting agents were used to cement the restorations. The crowns were evaluated according to the California Dental Association's quality assessment system., Results: Three crowns were lost at follow-up. Of the 206 restorations, which completed the 6-year follow-up, 9 crowns were affected by mechanical complications and 7 crowns failed. All surviving crowns were ranked as either excellent or acceptable. Cumulative survival and success rates of 95.2 and 90.9%, respectively, were recorded., Conclusions: Within the limitations of the present study, Procera AllCeram crowns proved to be a reliable clinical option to restore both anterior and posterior missing teeth either on natural or implant abutments. The resin cement used in the present study performed better than the zinc phosphate luting agent., (© 2009 Wiley Periodicals, Inc.)