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OBJECTIVE: SARS-CoV-2 is a new Coronavirus identified as the cause of Corona- virus disease in 2019 (COVID-19). The epidemic spread in China and beyond its borders, involv- ing 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 in- fectious 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 treat- ed has changed. In fact, it should be mandato- ry 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 pres- ent 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 look- ing 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 proto- cols” AND “healthcare procedures” AND “individ- ual 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 pan- demic, everywhere in the World, it is necessary to impose all dentistry team both a serological screening and the vaccination, as already estab- lished for all health staff in Italy. CONCLUSIONS: For own safety, it is an import- ant for the whole dentistry category constantly update the devices and the protocols adopted, as well as monitoring the real infectious threats, which may occur.

The main objective of this narrative review was to provide an overview of DEFS (Diagnostic Esthetic Functional Splint), namely CAD/CAM manufactured, “snap-retained”, tooth-colored splints available by materials exhibiting a certain degree of elasticity (like polycarbonates or acetal resins) for restoring function, esthetics and occlusion in several clinical situations, before or as an intermediate alternative to undergoing the final treatment. The search strategy included all papers dealing with snap-retained prosthetic systems and was based on a literature review of papers available in electronic databases (Pubmed/Medline, Evidence-Based Dentistry, BMJ Evidence-Based Medicine, Dynamed, Embase, BMJ Clinical Evidence, Web of Science, Scientific reports); eligible papers were researched on Opengreyand a manual search was performed, as well. From the electronic databases emerged 13,199 records, many of which were duplicates. The grey literature and the manual research did not produce any eligible article. After duplicates removal, 7690 records were obtained. Titles, abstracts and keywords were analyzed. The studies concerning the topic of interest were examined by the reviewers and discussed. Although no evidence-based data were found in the literature, according to the authors’ clinical experience, the DEFS (Diagnostic Esthetic Functional Splint) is a very promising solution in multiple clinical situations, due to its diagnostic, therapeutical, functional and esthetic versatility.

Aim: to assess the fracture resistance of maxillary molars restored using lithium disilicate glass-ceramic (LDG) table-top restorations fabricated with two different production protocols. Methods: sixteen maxillary molars were randomly assigned to two groups (n = 8). The teeth received a preparation for a full-coverage table-top restoration with a 90° rounded shoulder margin. Restorations were fabricated using monolithic LDG blocks milled via Cerec 3 CAD/CAM System in group 1 (G1) and heat-pressed LDG in group 2 (G2). All table-tops were luted with Variolink II cement. The specimens were loaded to fracture after thermomechanical aging (1 250 000 cycles). A qualitative analysis on the type of fracture was conducted. Collected data were statistically analyzed with non-parametric test (Mann Whitney U-test). Results: the mean load to fracture was 2395.01 ± 150.96 N in G1 and 1796.58 ± 307.27 N in G2; the difference was statistically significant (p < 0.05). The majority of the specimens showed restorable fractures (6 specimens in G1 and 6 specimens in G2). Conclusion: the milled CAD/CAM LDG table-top restorations withstood higher load before fracturing than the restorations made with the heat-pressed LDG production protocol.

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 mm2 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.

Aim The main objective of the present systematic review was to investigate the validation of no-preparation ceramic veneers as restorations. Materials and Methods Pubmed, Evidence-Based Dentistry, BMJ Clinical Evidence, Embase, Dynamed and Opengrey were analyzed in order to identify randomized controlled clinical trials evaluating the clinical outcomes of no-preparation ceramic veneers; manual researches were performed as well. Results Database search produced 2551 records. After removal of duplicates and a careful examination of titles and abstracts, the reviewers excluded all of the studies. Manual and grey literature did not yield any other relevant article. Conclusions Due to the lack of data, at the moment achieving a definitive clinical statement regarding the “no-prep” technique is not possible. Further clinical studies are needed to assess the effectiveness of no-preparation ceramic veneers. No-prep veneers can be considered as conservative treatments which should be carefully recommended and request a cautious selection of cases. Further controlled clinical researches are necessary to clearly identify predictable clinical protocols and evaluate the long-term outcomes of such restorations.

Una revisione clinica e sperimentale dell’impiego di zirconia e disilicato di litio nelle riabilitazioni protesiche e una serie di consigli clinici validati dalla più recente letteratura scientifica per una selezione accurata e corretta delle ceramiche metal-free.

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.

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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 as- sessed 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 unscrew- ing, 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 satisfac- tory 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.

Aim To evaluate the 4-year clinical outcomes of ceramic veneered CAD/CAM Co-Cr single crowns supported by natural teeth in posterior regions. Material and methods Eighty-nine patients were provided with 120 ceramic veneered CAD/CAM Co-Cr single crowns replacing either premolars and molars. Specific inclusion criteria were set and tooth preparations were standardized and performed by undergraduate students under the supervision of 2 expert prosthodontists. CAD/CAM Co-Cr frameworks were fabricated and veneered with ceramics. The restorations were cemented using a self-etching, dual-cure resin luting agent. The patients were recalled at follow-up every 6 months after baseline evaluation, for a total observational period of 4 years. The survival and success rates of the restorations were evaluated. The technical and esthetic outcomes were examined using the United States Public Health Service criteria. The biologic outcomes were analyzed at abutments and contralateral teeth and descriptive statistics were performed. Results None of the SCs was lost at follow-up, resulting in 100% cumulative survival rate and 99.2% cumulative success rates. No losses of retention were recorded. One hundred and eighteen restorations were rated alpha in all the measured parameters. A minor chipping of the veneering porcelain was detected in 1 restoration. No significant differences between the periodontal parameters of test and control teeth were observed. Conclusions CAD/CAM Co-Cr single crowns proved to be a valid treatment option and a viable alternative to noble metal-ceramic restorations in posterior regions after 4 years of clinical function.

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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

Aim: To investigate in vitro the fracture resistance of two different post systems, a conventional one with post space preparation using a drill and an alternative one adapted to the canal shape. Methodology: After sample size calculation, the crowns of 26 single-rooted freshly-extracted teeth were removed with a disc 1 mm coronal to the cemento-enamel junction. The canals were shaped with Mtwo rotary files up to size 40, 0.06 tpaer and filled with the continuous wave of condensation technique leaving the coronal 9 mm of the canal unfilled. After the post space preparation by a dedicated drill, double-tapered fibre posts (DT Light-Post) were cemented in half of the roots (G1, n = 13). 0.06 tapered fibre posts (Tech S Endoshape) were trimmed to fit the canal of the remaining roots (G2, n = 13) and then cemented without post space preparation. A self- adhesive cement (RelyX Unicem) was used in both groups. The posts were cut 5 mm from the root coronal surface. The specimens were embedded in acrylic resin and the top of the post was loaded under continuous compressive force (45°, 0.75 mm/min) to measure the maximum breaking load (N). Data were statistically analyzed by using a Student’s t-test (α = 0.05). Results: The mean maximum breaking loads ±SD were G1 = 164.07 ±21.54 and G2 = 151.22 ±14.69. The difference was not statistically significant (P = 0.093). Only post fractures were detected, with all the roots remaining intact. Conclusions: Within the limitation of the study, conservative posts without post space preparation performed similarly to conventional ones. In order to avoid procedural errors during the post space preparation and to spare tooth structure a conservative approach seems advisable.

Objectives: The present in vitro study aimed at evaluating the influence of a novel nanocomposite material on implant primary stability by means of periimplants scaffolds. Methods: Thirty-two titanium implants (Winsix, Biosafin) with an innovative design were modified with three-dimensional bioactive scaffolds made up of a new hybrid ceramo-polymeric material. The biomimetic nanocomposite material was designed to promote the precipitation of hydroxyapatite nanoinclusions in periimplant bone. The scaffolds were fabricated as a foamed hydrogel covering the coronal area of the implants; the material was characterized by swelling in contact with biological fluids, with a polymerization kinetic of 0.1 mm/hour. The modified implants were inserted in freshly explanted tibiae of minipigs; 16 standard implants were used as control. Then, the tibiae were kept hydrated in physiological solution and the implants removed after 1, 6, 12 and 24 hours. An electronic device was used to measure the removal torque and the data were statistically analyzed. Results: Insertion torque values ranging between 37 and 56 Ncm were recorded. Mean removal torque values of 61, 67, 79 and 86 were evidenced after 1, 6, 12 and 24 hours respectively. The ANOVA showed statistically significant differences between removal torque values (p

Objectives: The present in vivo animal study aimed at evaluating the osseointegration of biomimetic bone scaffolds made up of an innovative nanocomposite material. Methods: A novel nanocomposite hybrid ceramo-polymeric material was designed and produced to interact with bone tissue at nanoscale interfaces. The chemical, physical and mechanical properties of the material were analyzed and characterized. The highly bioactive material was designed to fabricate three-dimensional bone scaffolds in order to promote osseointegration through the precipitation of hydroxyapatite nanoinclusions in periimplant bone. The biomimetic nanocomposite was fabricated as a foamed hydrogel swelling in contact with biological fluids. The biofidelity of the scaffolded implant system was simulated in a digital environment and the stress and strain distributions assessed using three-dimensional Finite Element Analysis. The biomimetic properties of the nanocomposite material were validated in vivo in an animal model, using three-dimensional scaffolds around dental implants inserted in tibiae of minipigs. After explantation, such tibiae were subjected to micro-computed tomography scannings to evaluate bone-to-implant and bone-to- scaffold contact. Results: The chemical, physical and mechanical laboratory tests showed high biomimetic properties for the innovative hybrid material. Stress and strain distributions within the physiological range of trabecular adaptive organization (2000-3000 με) were noticed in periimplant bone with the Finite Element Analysis. The micro-CT scannings showed comparable percentages of bone contact at level of both the scaffolds and the titanium of the implants. Conclusions: The innovative hybrid ceramo-polymeric nanomaterial proved to promote accelerated osseointegration in post-surgical early healing phases.