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Objectives: To compare marginal gap width and depth with different cementation systems, excess removal, and after polishing. Method and materials: In total, 80 composite crowns were milled, divided into ten groups, and cemented on identical artificial teeth. Eight crowns per group were fixed with (i) zinc phosphate cement (ZnOPh), (ii) glass-ionomer cement (GIC), (iii) resin-reinforced glass-ionomer cement (GIC mod), (iv) dual-curing adhesive composite (Comp dual), or (v) dual-curing self-adhesive composite (Comp SE dual). Excess removal was performed with a scaler after brief light-cure (tack-cure), final light-cure, during rubber or gel phase or by wiping with foam pellet. Curing was completed in chemical, dark cure, or light-curing modus. The specimens were polished and stored in water (37°C). The margins were digitized using a 3D laser-scanning microscope (VK-X100 series, Keyence). The width and the depth of the marginal gap were measured at 10 points between the crown margin and the preparation margin. Results: The width after excess removal varied between 65.1 ± 15.7 µm (Comp dual, wipe, with polishing) and 208.6 ± 266.7 µm (Comp SE dual, dark cure, without polishing). The depth varied between 29.8 ± 22.2 µm (Comp dual, wipe, with polishing) and 89.5 ± 45.2 µm (Comp SE dual, dark cure, without polishing). The impact on gap width and depth was detected for fixation material, excess removal, and polishing. Conclusion: The gap depth and width depend on the luting material and the mode of access removal. Polishing can improve the gap quality, especially for GIC and resin-based systems. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare the flexural strength, Weibull modulus (reliability), marginal gap, and internal fit (internal gap) of 4 materials for milling or 3-dimensional (3D) printing of definitive and provisional crowns: IPS e.max CAD (IEC), Paradigm MZ100 Block (PMB), Permanent Crown Resin (PCR), and Temporary CB Resin (TCR). Flexural strength was tested by subjecting sectioned milling blocks (IEC and PMB) or 3D-printed bars (PCR and TCR) to a 3-point bending test in a universal testing machine (n = 15 per material). Crowns were milled or 3D printed, and the marginal gap and internal fit were measured using microcomputed tomography (n = 5 per material). The data were analyzed with a t test and compared using analysis of variance (ANOVA) with Tukey post hoc comparisons (α = 0.05). The groups demonstrated the following mean (SD) flexural strength values: IEC, 335.50 (28.97) MPa; PMB, 154.34 (21.03) MPa; PCR, 128.09 (7.30) MPa; and TCR, 126.29 (9.23) MPa. A 1-way ANOVA revealed significant differences in the flexural strengths of sectioned and 3D-printed bars (P < 0.001). The PMB group showed the lowest Weibull modulus (8.77), indicating its poor reliability. The IEC group showed the smallest marginal gap, 53.42 (31.99) µm; this value was significantly smaller than the gap in the TCR group (P < 0.001) but not the PCR or PMB group. The PMB group had the smallest internal fit discrepancy (87.44 [37.60] µm) but was not significantly different from PCR, while TCR had a significantly greater internal fit discrepancy (130.61 [65.16] µm) than IEC, PMB, and PCR (P< 0.001). The occlusal internal fit discrepancies of 3D-printed crowns were significantly greater than those of milled crowns (P< 0.001). There was no statistically significant difference in flexural strength between the 3D-printed definitive (PCR) and provisional (TCR) materials. When the data were combined according to manufacturing method, the marginal gap and internal fit of crowns fabricated with 3D printing were comparable to those of milled crowns, and all mean marginal gaps were within a clinically acceptable limit of less than 120 µm. [ABSTRACT FROM AUTHOR]

Background: There is limited knowledge on the fabrication trueness and fit of additively or subtractively manufactured complete‐arch implant‐supported frameworks in recently introduced polymers. Purpose: To evaluate the trueness and marginal fit of additively or subtractively manufactured polymer‐based complete‐arch implant‐supported frameworks, comparing with those of strength gradient zirconia frameworks. Materials and Methods: A typodont model with 4 implants (left first molar (abutment 1), left canine (abutment 2), right canine (abutment 3), and right first molar (abutment 4)) was digitized (ATOS Core 80 5MP) and an implant‐supported complete‐arch framework was designed. This design file was used to fabricate frameworks from 5 different materials: strength gradient zirconia (SM‐ZR), high impact polymer composite (SM‐CR), nanographene‐reinforced PMMA (SM‐GR), PMMA (SM‐PM), and additively manufactured temporary resin (AM) (n = 10). These frameworks were digitized and each scan file was virtually segmented into 4 regions (abutments, occlusal, overall without occlusal, and overall). The surface deviations at these regions, and linear and interimplant distance deviations were evaluated (Geomagic Control X). Marginal gaps were evaluated according to triple‐scan protocol after seating frameworks on the model with the 1‐screw test. Data were statistically analyzed (α = 0.05). Results: Surface deviations of all regions differed among tested materials (p ≤ 0.001). AM frameworks mostly had surface deviations that were similar to or lower than those of other materials (p ≤ 0.031), except for the occlusal surface, where it mostly had higher deviations (p ≤ 0.013). Abutment 4 of SM‐CR had higher linear deviations than abutment 2 (p = 0.025), and material type did not affect the linear deviations within abutments (p ≥ 0.171). Interimplant distance deviations differed within and among materials (p ≤ 0.017), except for those between abutments 1 and 2 among materials (p = 0.387). Marginal gaps of subtractively manufactured materials differed among abutments, while those of abutments 3 and 4 differed among materials (p ≤ 0.003). AM frameworks mostly had lower marginal gaps at abutments 3 and 4 (p ≤ 0.048). Conclusions: Although there was no clear trend among tested materials for measured deviations, marginal gaps of additively manufactured resin were mostly lower than those of subtractively manufactured materials and did not differ among abutment sites. Nevertheless, the differences in measured deviations among materials were small and marginal gaps were within the previously reported acceptability thresholds. [ABSTRACT FROM AUTHOR]

Abstract Background Various types of crowns are used for full-coverage restoration of primary teeth affected by caries, developmental defects, or after pulp therapy. Prefabricated Stainless Steel and Zirconia crowns are commonly utilized. Bioflx crowns, which blend the properties of Stainless Steel and Zirconia, provide a flexible and aesthetically pleasing alternative. Aim This study aimed to evaluate the vertical marginal gap and fracture resistance of Bioflx pediatric crowns compared to Zirconia and Stainless Steel crowns following thermomechanical aging. Methods This in-vitro study was conducted using mandibular second primary crowns of three different materials (n = 30). Crowns were divided into three groups; Zirconia crowns group (n = 10, Nu Smile, USA), Bioflx crowns group (n = 10, Nu Smile, USA) and Stainless Steel crowns group (n = 10, Nu Smile, USA). The crowns were cemented onto standardized acrylic resin dies and subjected to thermomechanical aging. Vertical marginal gap measurements were obtained using a USB digital microscope with an integrated camera, while fracture resistance was assessed with a universal testing machine. Data were analyzed for outliers and tested for normality using the Shapiro-Wilk or Kolmogorov-Smirnov tests, with statistical significance set at 0.05. Results Significant differences were observed in the vertical marginal gaps among the groups after cementation and thermomechanical aging (P = 0.013 and P = 0.001, respectively). Zirconia crowns exhibited the largest average marginal gap, followed by Bioflx and Stainless Steel crowns. Stainless steel crowns demonstrated the highest fracture resistance, followed by Bioflx crowns, while Zirconia crowns showed the lowest. Conclusions Bioflx crowns exhibit the largest vertical marginal gap but show greater fracture resistance compared to Zirconia crowns, although they are still less resistant than Stainless Steel crowns after undergoing thermomechanical aging.

Background: This study compared the marginal gaps of CAD/CAM lithium disilicate (LDS) crowns constructed using a contemporary and older scanner/milling unit combination at three different cement spaces. Methods: Twenty‐four undergraduate students prepared a Columbia model lower left first molar for an LDS crown in a simulated environment. From each crown preparation, one LDS crown was constructed using an E4D scanner/E4D milling unit (E4DS/E4DM) and TRIOS 3 scanner/Sirona inLab MC X5 milling unit (TRIO/MCX5) at cement space settings of 50, 100 and 200 μm. Each LDS crown was positioned onto the original crown preparation, and then a stereomicroscope was used to make three vertical marginal gap measurements at four locations (mid‐buccal, mid‐lingual, mid‐mesial and mid‐distal). The mean marginal gap (MMG) was calculated for each crown and each individual tooth surface. Results: The MMGs of CAD/CAM LDS crowns constructed by TRIO/MCX5 were 72.31 at 50, 63.73 at 100 μm and 46.23 μm at 200 μm, which were smaller than E4DS/E4DM at each cement space. Conclusions: Increasing the cement space decreased the MMG in both scanner/milling unit combinations. The smallest MMG was found using the newer scanner/milling unit at the 200 μm cement space. © 2024 Australian Dental Association. [ABSTRACT FROM AUTHOR]

Background: To avoid cortical compression, several implant systems have included in the protocol dedicated drills aimed at widening the cortical region of osteotomy. However, the manual execution of this operation does not guarantee the necessary precision. Hence, the present study aimed to determine the optimal size of the recipient site at the level of the alveolar crest in relation to the size of the coronal region of the implant to achieve the best healing result. Materials and methods: Blades of different diameters were incorporated into the coronal part of the implant to prepare the cortical region of the mandibular alveolar bone crest in different dimensions in relation to the collar of the implant. The differences in diameter of the blades in relation to the collar of the implant were as follows: one control group, -175 μm, and three test groups, 0 μm, + 50 μm, or + 200 μm. Results: The marginal bone loss (MBL) at the buccal aspect was 0.7 mm, 0.5 mm, 0.2 mm, and 0.7 mm in the − 175 μm, 0.0 μm, + 50 μm, + 200 μm groups, respectively. The differences were statistically significant between group + 50 μm and control group − 175 μm (p = 0.019), and between + 50 μm and + 200 μm (p < 0.01) groups. The level of osseointegration at the buccal aspect was more coronally located in the test groups than in the control group, whereas the bone-to-implant contact percentage was higher in the + 50 μm and + 200 μm groups. However, these differences were not statistically significant. Conclusions: The lowest bone crest resorption and highest levels of osseointegration were observed in the 0.0 μm and + 50 μm groups. The cortical region where the blades had performed their cutting action showed regular healing with perfect hard and soft tissues sealing in all the groups. Cortical blades gathered bone particles, particularly in the + 200 μm group, which were incorporated into the newly formed bone. The results from the present experiment provide support to the use of blades that produce a marginal gap of 50 μm after implant insertion. [ABSTRACT FROM AUTHOR]

Background: This study aimed to evaluate the biological behavior of a novel implant design incorporating decompressive cervical blades. Hence, the aim of the present study was to evaluate the healing outcomes in cortical regions where decompressive protocols were implemented using implants equipped with blades and installed applying a bicortical anchorage. Materials and Methods: Blades with varying diameters were integrated into the coronal portion of the implant to prepare the cortical region of rabbit tibiae. The blade diameters differed from the implant collar by the following amounts: control group (0 µm), +50 µm, and +200 µm. Results: No marginal bone loss was detected. Instead, all implants exhibited new bone formation in the coronal region. Complete closure was observed in the CG-0 group, as well as in the TG-50 and TG-200 groups, despite the presence of marginal gaps without primary bone contact at installation. In the apical region, most implants breached the cortical layer. Nevertheless, new bone formation in this region completely closed the osteotomy, effectively isolating the internal environment of the tibia from the external. Conclusions: The use of a blade incorporated into the implant body enabled precise preparation of the cortical layer, allowing for controlled decompression in the targeted area. This technique resulted in optimal osseointegration with no loss of marginal bone, and complete restoration of marginal gaps ranging from 0 µm to 200 µm. [ABSTRACT FROM AUTHOR]

Objectives: This in vitro study examined the marginal integrity of experimental composite materials doped with bioactive glass (BG). Materials and methods: Class-II MOD cavities were prepared and restored with one of the following composite materials: a commercial composite material as a reference (Filtek Supreme XTE), an experimental composite doped with BG 45S5 (C-20), and an experimental composite doped with a fluoride-containing BG (F-20). Six experimental groups (n = 8) were used, as each of the three composites was applied with (+) or without (-) a universal adhesive (Adper Scotchbond Multipurpose). All specimens were subjected to thermocycling (10,000 x, 5–55 °C) and then additionally stored in artificial saliva for eight weeks. Scanning electron micrographs of the mesial and the distal box were taken at three time points (initial, after thermocycling, and after eight weeks of storage in artificial saliva). The margins were classified as “continuous” and “non-continuous” and the percentage of continuous margins (PCM) was statistically analyzed (α = 0.05). Results: In most experimental groups, thermocycling led to a significant decrease in PCM, while the additional 8-week aging had no significant effect. F-20 + performed significantly better (p = 0.005) after 8 weeks storage in artificial saliva than the reference material with adhesive, while no statistically significant differences were observed at the other two time points. C-20 + exhibited significantly better PCM than the reference material with adhesive after thermocycling (p = 0.026) and after 8 weeks (p = 0.003). Conclusions: Overall, the experimental composites with BG showed at least as good marginal adaptation as the commercial reference, with an indication of possible re-sealing of marginal gaps. Clinical relevance: Maintaining or improving the marginal integrity of composite restorations is important to prevent microleakage and its likely consequences such as pulp irritation and secondary caries. [ABSTRACT FROM AUTHOR]

The objective of this in vitro study was to evaluate the effect of incorporated polylysine antibacterial particles (PLS) in two different types of adhesive resin cements on marginal adaptation of indirect crown restorations fabricated from IPS e.max ZirCAD (LT block). Material and methods: 32 maxillary first premolar teeth were prepared to receive indirect crown restorations with the following preparation criteria: occlusal-gingival height of 4 mm, 3% axial wall taperness, and a 0.8 mm circumferential chamfer finishing line that was checked with a digital caliper. The prepared teeth were randomly assigned to four main groups (n=8) according to the type of resin cement used to lute indirect restorations: 1) Rely C: cemented with RelyXTM U200 cement, 2) RelyPLS: cemented with RelyXTM U200 cement incorporated by PLS, 3) BrC: cemented with BreezeTM cement and 4) BrPLS: cemented with BreezeTM cement incorporated BreezeTM cement. The teeth were digitally scanned and crown design was performed using Sirona InLab CAD 15.1 software. Each restoration was cemented to its respective tooth and a 230X magnification power digital microscope was used to measure the marginal gap in µm. The data was then analysed statistically; Independent t-test and a paired t-test were used. Result: The results showed that the crowns cemented by RelyC showed significantly lower mean values of the marginal gap compared to BrC (28.969 μm, 31.06 μm), respectively (p0.05). Furthermore, the results of the paired t-test showed a statistically higher marginal gap after cementation compared to before cementation in all groups (p

Background/purpose: Nowadays, zirconia-based framework has been used for longspan or full-arch fixed dental prostheses (FDPs). This study aimed to evaluate the effect of pontic distribution on marginal and internal gaps of five-unit anterior zirconiabased DPs. Materials and methods: Right maxillary central incisor and second premolar were selected as terminal abutments and three different edentulous conditions with one nonterminal abutment were simulated. Marginal and internal gaps in each zirconia-based samples(n = 10) were examined by computer-aided replica technique. Five regions, including marginal gaps at mesial or distal finishing line, internal gaps at the mesial or distal axial wall, and occlusal surface, were statistically analyzed (α = .05). Results: Most of marginal gaps and internal gaps at axial wall were clinically acceptable, but larger at occlusal surface. For the three experimental groups, clinically accepted percentage with qualified gaps were less than 30%.There were statistical differences at axial wall over pontic side and marginal gaps over non-pontic side between groups (P

Background: In everyday dentistry, monolithic single crowns can be cemented with self-adhesive resin cements. The aim of this in vitro study was to evaluate how the marginal adaptation of full monolithic zirconia-reinforced lithium silicate (ZLS) single crowns is influenced by three different self-adhesive resin cements. Methods: Forty-five typodont teeth fully prepared for full monolithic crowns were divided into three groups (fifteen each) for the use of three different self-adhesive resin cements. A fourth control group (Temp-bond) was created by taking five teeth from each group before cementation with self-adhesive resin cements. All forty-five abutments were scanned using a Primescan intra-oral scanner (IOS), followed by computer-aided design (CAD) and computer-aided manufacturing (CAM) of zirconia-reinforced lithium silicate (ZLS) full crowns using a four-axis machine. Initially, the crowns of the control group were fixed to the abutments using Temp-bond, and the marginal gap was evaluated using a scanning electron microscope (SEM). After removing the control group crowns from the abutments, fifteen crowns in each group were cemented using a different self-adhesive resin cement and observed under SEM for evaluation of the marginal gap. A Kolmogorov–Smirnov test was performed, indicating no normal distribution (p < 0.05), followed by Mann–Whitney tests (α = 0.05). Results: The total mean marginal gap of the temp-bond control group was significantly lower compared to all three groups of self-adhesive resin cement (p < 0.0005). The total mean marginal gap of the G-cem ONE group was significantly lower compared to the TheraCem group (p < 0.026) and RelyX U200 group (p < 0.008). The total mean marginal gap of the TheraCem group was significantly higher than the G-cem ONE group (p < 0.026) but showed no significant difference with the RelyX U200 group (p > 0.110). Conclusions: All four groups showed a clinically acceptable marginal gap (<120 microns). Although all three groups of self-adhesive resin cement showed a significant increase in the marginal gap compared to the temp-bond control group, they were within the limits of clinical acceptability. Regarding the marginal gap, in everyday dentistry, it is acceptable to use all three self-adhesive resin cements, although the G-cem ONE group exhibited the lowest marginal gap for ZLS single crowns. [ABSTRACT FROM AUTHOR]

This study aimed to compare the impact of CAD/CAM closed systems and open systems on the marginal gap of monolithic zirconia-reinforced lithium silicate (ZLS) ceramic crowns, as both systems are used in everyday dentistry, both chair-side and laboratory. For the closed system, 20 plastic teeth were scanned by a Primescan intra-oral scanner (IOS), and for the open system, the same number of plastic teeth were scanned by Trios 4 IOS. For the closed system, CEREC software was used, and for the open system, EXOCAD software was used. All 40 ZLS crowns were grinded by the same four-axis machine and cemented with Temp-bond, followed by self-adhesive resin cement. For each type of cement, an evaluation of the marginal gap was conducted by scanning electron microscopy (SEM). Before comparisons between the groups, a Kolmogorov–Smirnov test was performed on the study variables showing a normal distribution (p > 0.05). Independent T tests (α = 0.05) and paired-sample T tests (α = 0.05) were used. The independent T test found no significant mean marginal gap differences in the zirconia-reinforced lithium silicate crowns bonded with Temp-bond and scanned by Primescan (28.09 μm ± 3.06) compared to Trios 4 (28.94 μm ± 3.30) (p = 0.401), and there was no significant mean marginal gap differences in zirconia-reinforced lithium silicate crowns bonded with self-adhesive resin cement (Gcem ONE) and scanned by Primescan (46.70 μm ± 3.80) compared to Trios 4 (47.79 μm ± 2.59) (p = 0.295). Paired-sample T tests showed significantly higher mean marginal gaps with Gcem ONE compared to Temp-bond for the total mean marginal gap when scanning with Primescan (p = 0.0005) or Trios 4 (p = 0.0005). In everyday dentistry, both closed systems (Primescan with Cerec) and open systems (Trios 4 with Exocad) can be used to achieve an acceptable (<120 µm) marginal gap for ZLS CELTRA® DUO single crowns. There is a significant difference between cementation with Temp-bond and Gcem ONE self-adhesive resin cement (p < 0.05). [ABSTRACT FROM AUTHOR]

Nowadays, zirconia-based framework has been used for longspan or full-arch fixed dental prostheses (FDPs). This study aimed to evaluate the effect of pontic distribution on marginal and internal gaps of five-unit anterior zirconiabased DPs. Right maxillary central incisor and second premolar were selected as terminal abutments and three different edentulous conditions with one nonterminal abutment were simulated. Marginal and internal gaps in each zirconia-based samples(n = 10) were examined by computer-aided replica technique. Five regions, including marginal gaps at mesial or distal finishing line, internal gaps at the mesial or distal axial wall, and occlusal surface, were statistically analyzed (α =.05). Most of marginal gaps and internal gaps at axial wall were clinically acceptable, but larger at occlusal surface. For the three experimental groups, clinically accepted percentage with qualified gaps were less than 30%.There were statistical differences at axial wall over pontic side and marginal gaps over non-pontic side between groups (P <0.05). For sum of gaps of all abutments in each group, statistical differences were found at marginal and axial wall (P < 0.05). As for those on terminal and non-terminal abutments, statistical differences were found on second premolar (P < 0.05). Except for occlusal surface, the overall marginal gaps and internal gaps at axial wall of five-unit anterior zirconia-based FDPs with different pontic distribution were clinically acceptable. However, the percentage with qualified gaps were low (<30%). Greater gaps were noted when adjacent pontic existed. Different pontic size and distribution with curvature had an influence on the gaps. [ABSTRACT FROM AUTHOR]

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Purpose: Internal and marginal fit accuracy of an implant-supported fixed partial denture (I-FPD) along with passive fit are required for long-term clinical success. This study compared the fit accuracy of three-unit CAD/CAM-fabricated cement-retained I-FPDs milled from pre-sintered cobalt-chromium (Co-Cr) and zirconia (Zr) and evaluated the effect of applying porcelain. Materials and Methods: Two implant analogs were positioned parallel at first premolar and first molar sites in an acrylic model. Their corresponding abutments were tightened with 25-Ncm torque force. Four groups were designed: two groups of I-FPD frameworks with pre-sintered Zr (ZrF) and soft millable Co-Cr alloy (SF) blocks, and two groups by applying porcelain to the Co-Cr (SP) and Zr (ZrP) frameworks (n = 4 in each group). Absolute marginal gap (AMG), marginal gap (MG), and internal discrepancies were measured. Kolmogorov-Smirnov, Levene, one-way analysis of variance (ANOVA), and Scheffe tests were used for statistical analysis using SPSS software version 22 at a significance level of .05. Results: All measured criteria were significantly different from each other (all P values < .001). The rankings from the lowest gap to the highest gap for the main criteria were as follows: MG: SF < SP < ZrF < ZrP; AMG and internal discrepancies: SF < SP < ZrP < ZrF. Comparing molars and premolars, molars had smaller MGs, larger internal discrepancies, and smaller AMG in ZrP but larger AMG in SP. Conclusion: All three-unit CAD/CAM-fabricated cement-retained I-FPDs were in the clinically acceptable range of fit accuracy. The lowest and highest misfit values were observed in the SF and ZrF groups, respectively. [ABSTRACT FROM AUTHOR]

Background: This study compared the influence of crystallization on marginal gap adaptation by using computer-aided design and manufacturing (CAD-CAM) for producing monolithic zirconia-reinforced lithium silicate (ZLS) ceramic crowns. Methods: A total of 25 plastic teeth were scanned using a Primescan intra-oral scanner (IOS), and ZLS crowns were ground. For each unit (abutment and crown), the marginal gap was evaluated pre crystallization and post crystallization at four regions of interest through the use of a scanning electron microscope (SEM). To compare the marginal gap between the two groups, a Kolmogorov–Smirnov test performed on the study variables indicated a normal distribution (p > 0.05) followed by paired samples T-tests (α = 0.0005). Results: After crystallization, there were significantly higher circumferential marginal gaps (CMGs) for all four surfaces (distal (p = 0.0005), mesial (p = 0.0005), palatal (p = 0.0005), and buccal (p = 0.0005)). The total mean marginal gap (MMG) revealed a significantly higher result for the post-crystallization group (79.82 ± 7.86 μm) compared to the pre-crystallization group (24.25 ± 5.49 μm). Conclusions: The post-crystallization group showed a significantly higher marginal gap compared to the pre-crystallization group in all parameters, but both groups were in the clinically accepted threshold (<120 microns). In terms of the marginal gap, it is arguable whether to carry out post-crystallization for CELTRA® DUO crowns and achieve better mechanical properties but significantly increase the marginal gap. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the design and location of supporting structures on the marginal and internal gap of interim restorations. Materials and methods: A mandibular right first molar resin tooth was prepared for a full coverage crown and scanned using a laboratory scanner (3Shape D900). The scanned data were converted into standard tessellation language (STL) format and an indirect prosthesis was designed using computer‐aided design (CAD) software (exocad DentalCAD). The STL file was used to fabricate a total of 60 crowns with a 3D printer (EnvisionTEC Vida HD). The crowns were printed using E‐Dent C&B MH resin and divided into 4 groups based on four different support structure designs, including supports on the occlusal (0° group), buccal and occlusal (45° group), buccal (90° group), and a new design consisting of horizontal bars placed on all surfaces and line angles (Bar) (n = 15). The silicone replica technique was used to determine the gap discrepancy. Fifty measurements were obtained for each specimen to examine the marginal and internal gaps by using a digital microscope (Olympus SZX16) at ×70 magnification. Additionally, the marginal discrepancy at different locations of the tested crowns, including buccal (B), lingual (L), mesial (M), and distal (D), as well as the maximum and minimum marginal gap intervals among groups, were analyzed. The collected data were analyzed using factorial ANOVA, followed by the Tukey HSD test for multiple comparisons (a = 0.05). Results: There was a significant difference in marginal and internal gaps among the groups (p < 0.001). The buccal placement supports (90° group) had the least marginal and internal discrepancies (p < 0.001). The new design group showed the highest marginal and internal gap. The marginal discrepancy in different locations of the tested crowns (B, L, M, D) was found to be significantly different among the groups (p < 0.001). The mesial margin of the Bar group had the largest marginal gap, whereas the buccal margin of the 90° group had the lowest marginal gap. The new design had a significantly smaller difference between the maximum and minimum marginal gap intervals than other groups (p < 0.001). Conclusion: The location and design of the supporting structures affected the marginal and internal gaps of an interim crown. The buccal placement of supporting bars (90° printing orientation) showed the smallest mean internal and marginal discrepancies. [ABSTRACT FROM AUTHOR]

Background. This study evaluated the influence of different tooth preparation techniques and zirconia materials on marginal adaptation. Methods. Forty-eight healthy human maxillary first premolars were divided into two primary groups based on preparation design: group A (chamfer) and group B (vertical). Within each main group, there were three subgroups, comprising eight teeth each, distinguished by the type of zirconia material employed (Zircad LT, MT, and Prime by Ivoclar Vivadent). All the samples were prepared by the same operator using a dental surveyor. Intraoral scanning was performed on the prepared teeth. SironaInLab CAD 20.0 software was used to design crowns, which were subsequently generated using a 5-axis milling machine. The crowns were cemented to their respective teeth with self-adhesive resin cement. Marginal gap measurements were taken in micrometers (μm) before and after cementation at 16 sites per sample using a digital microscope at×230 magnification. The collected data were evaluated using statistical analysis using the independent t-test, paired t-test, and ANOVA at an 0.05 significance level. Results. The vertical preparation group exhibited the smallest marginal gap, while the chamfer group displayed the largest. This disparity was statistically significant (P

Background: This study aimed to evaluate the biological behavior of a novel implant design incorporating decompressive cervical blades. Hence, the aim of the present study was to evaluate the healing outcomes in cortical regions where decompressive protocols were implemented using implants equipped with blades and installed applying a bicortical anchorage. Materials and Methods: Blades with varying diameters were integrated into the coronal portion of the implant to prepare the cortical region of rabbit tibiae. The blade diameters differed from the implant collar by the following amounts: control group (0 µm), +50 µm, and +200 µm. Results: No marginal bone loss was detected. Instead, all implants exhibited new bone formation in the coronal region. Complete closure was observed in the CG-0 group, as well as in the TG-50 and TG-200 groups, despite the presence of marginal gaps without primary bone contact at installation. In the apical region, most implants breached the cortical layer. Nevertheless, new bone formation in this region completely closed the osteotomy, effectively isolating the internal environment of the tibia from the external. Conclusions: The use of a blade incorporated into the implant body enabled precise preparation of the cortical layer, allowing for controlled decompression in the targeted area. This technique resulted in optimal osseointegration with no loss of marginal bone, and complete restoration of marginal gaps ranging from 0 µm to 200 µm.

Abstract Background This study aimed to evaluate and compare the marginal gap using two different methods and the internal fit of 3D printed and zirconia crowns. Methods 3Y-TZP zirconia crowns (n = 20) were manufactured using subtractive milling (group M) and 3D printed (group P). The marginal gap was measured at 60 points using vertical marginal gap technique (VMGT). On the other hand, the silicone replica technique (SRT) was used to evaluate the internal fit and was divided into 4 groups: marginal gap, cervical gap, axial gap, and occlusal gap where the thickness of light impression was measured at 16 references. The numerical data was tested for normality using Shapiro–Wilk's test. They were found to be normally distributed and were analyzed using an independent t-test. Results Using VMGT, group P had significantly higher mean marginal gap values of 80 ± 30 µm compared to group M = 60 ± 20 µm (p

Background.: This study evaluated the influence of different tooth preparation techniques and zirconia materials on marginal adaptation. Methods.: Forty-eight healthy human maxillary first premolars were divided into two primary groups based on preparation design: group A (chamfer) and group B (vertical). Within each main group, there were three subgroups, comprising eight teeth each, distinguished by the type of zirconia material employed (Zircad LT, MT, and Prime by Ivoclar Vivadent). All the samples were prepared by the same operator using a dental surveyor. Intraoral scanning was performed on the prepared teeth. SironaInLab CAD 20.0 software was used to design crowns, which were subsequently generated using a 5-axis milling machine. The crowns were cemented to their respective teeth with self-adhesive resin cement. Marginal gap measurements were taken in micrometers (μm) before and after cementation at 16 sites per sample using a digital microscope at×230 magnification. The collected data were evaluated using statistical analysis using the independent t-test, paired t-test, and ANOVA at an 0.05 significance level. Results.: The vertical preparation group exhibited the smallest marginal gap, while the chamfer group displayed the largest. This disparity was statistically significant (P <0.05)> Conclusion.: The vertical preparation design illustrated significantly better marginal adaptation than the chamfer preparation design. Comparisons between materials showed comparable marginal gaps. The mean values of the marginal gaps in all groups increased significantly after cementation. [ABSTRACT FROM AUTHOR]

Abstract Background The aim of the study was to investigate the effect of material and occlusal preparation design on the internal fit and marginal gap of endocrowns made of Polyether ether ketone (PEEK) and lithium disilicate. Methods 32 endocrowns were fabricated on prepared mandibular molars and divided into two groups (n = 16) according to the material. Group L: lithium disilicate and Group P: PEEK. Each group was further subdivided into two subgroups (n = 8) according to the occlusal preparation design: full occlusal coverage (LF and PF) and partial occlusal coverage (LP and PP). Samples were analyzed using microcomputed tomography (µCT) with a voxel size of 6 μm to evaluate internal fit, and an optical microscope was used to evaluate the marginal gap. Data were collected, tabulated, and statistically analyzed. Numerical data were described as mean and standard deviation and compared using the ANOVA test. The level of significance was set at α P ≤ 0.05. Results All groups’ internal fit and marginal gaps values were within the acceptable clinical range. However, the lithium disilicates group recorded statistically significantly higher mean internal gap values than the PEEK groups. Regardless of the material, the difference between the two occlusal designs was not statistically significant in both internal fit and marginal gap records. Conclusion Within the limitations of this study, PEEK endocrown restorations revealed better internal fit and marginal gap than lithium disilicate endocrown restorations. The marginal and internal fit of both lithium disilicate and PEEK endocrown restorations were within the clinically acceptable range. The occlusal preparation design had no influence on the internal fit and marginal gap of the endocrown restoration.

Background: This study aimed to evaluate and compare the marginal gap using two different methods and the internal fit of 3D printed and zirconia crowns. Methods: 3Y-TZP zirconia crowns (n = 20) were manufactured using subtractive milling (group M) and 3D printed (group P). The marginal gap was measured at 60 points using vertical marginal gap technique (VMGT). On the other hand, the silicone replica technique (SRT) was used to evaluate the internal fit and was divided into 4 groups: marginal gap, cervical gap, axial gap, and occlusal gap where the thickness of light impression was measured at 16 references. The numerical data was tested for normality using Shapiro–Wilk's test. They were found to be normally distributed and were analyzed using an independent t-test. Results: Using VMGT, group P had significantly higher mean marginal gap values of 80 ± 30 µm compared to group M = 60 ± 20 µm (p < 0.001). Also, with the SRT, the marginal gap of group P (100 ± 10 µm) had significantly higher values compared to group M (60 ± 10 µm). The internal fit showed significant difference between the tested groups except for Axial Gap. Conclusions: Although milled crowns showed better results. The 3D printed zirconia crowns offer clinically acceptable results in terms of marginal adaptation and internal fit. Both VMGT and SRT are reliable methods for the assessment of the marginal gap. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this study was to evaluate the structural microporosity (MP) and marginal gap (MG) of different flowable composite resins placed with different instruments using micro-computed tomography (μCT). Materials and Methods: Standard Class II MOD cavities were prepared on 108 lower third molar teeth. Three different flowable composite resins; Filtek Bulk-fill, SDR Bulk-fill and I-Flow conventional flowable composite resin were applied to the cavities using a sharp explorer, a microbrush or an injector. After they were covered with a paste-like nanohybrid composite resin, μCT images were examined in terms of MP and MG. Statistical analysis of the data was performed using two-way ANOVA and Tukey’s post hoc tests. Results: MP was observed less in explorer group than microbrush and injector groups (p < 0.05). There was no significant difference between microbrush and injector groups (p > 0.05). i-FLOW flowable composite resin showed the highest MP rate compared to the other two groups (p < 0.05). There was no significant difference between SDR and Filtek Bulk-fill in MP (p > 0.05). In terms of MG, i-FLOW presented higher MG values than other two materials (p < 0.05), while the instruments showed similar results (p > 0.05). Conclusions: Additional occluso-gingivally vibration of flowable materials with an explorer may be useful in the placement. Bulk-fill composite resins are better than conventional flowable composite resin in terms of MP and MG.

Abstract Background This study aimed to evaluate the effect of virtual cement space and restorative materials on the fit of computer-aided design and computer-aided manufacturing (CAD-CAM) endocrowns. Methods A mandibular first molar tooth model received a butt joint margin endocrown preparation with a 2-mm occlusal thickness. Then, using a 3D-printing system, 120 copies of this prepared die were printed and assigned equally to three groups with different cement space settings (30, 60, and 120 μm) during the chairside CAD design. In the milling process, CAD-based models with a particular space setting were subdivided into four groups (n = 10) and fabricated from different CAD-CAM materials: Vita Suprinity (VS), Celtra Duo (CD), Lava Ultimate (LU), and Grandio blocs (GR). Finally, the endocrowns were stabilized over their corresponding models with siloxane and subjected to micro-computed tomography to measure the fit. Results The cement space that was predesigned at 30 μm generated the largest marginal discrepancy (from 144.68 ± 22.43 μm to 174.36 ± 22.78 μm), which was significantly different from those at 60 μm and 120 μm (p

Purpose: This work evaluates the internal and marginal adaptation of implant-assisted overdenture cobalt–chromium (Co–Cr) bars manufactured using conventional as well as CAD/CAM subtractive and selective laser melting (SLM) utilizing two scanning techniques. Methods: An edentulous study model containing four dental implants placed at teeth sites 36, 33, 43, and 46 was used. The study cast was scanned and compared to the virtual casts developed from two scanning techniques, straight and zigzag motion, using the in silico superimposition process. Then, conventional techniques were used to produce full-arch bars that were compared to the bars fabricated using the two scanning techniques and CAD/CAM subtractive and additive techniques. Results: The conventional impression and casting techniques had the smallest marginal gap among the groups (P-value

Purpose: To evaluate the effect of finish line design (chamfer and feather‐edge) and ceramic type on the internal and marginal fits of fixed partial dentures on abutment teeth. Materials and methods: Two typodont mandibular casts, missing right first premolar tooth, received tooth preparation on canine and second premolar abutments (one cast with chamfer finish line and the other cast with feather‐edge finish line). The preparation segment of each typodont model was scanned, 3D printed in resin, and then invested and casted in metal to obtain two metal models. Polyvinyl siloxane impressions were made for the metal models and poured in type IV stone. The stone models (n = 40) were randomly assigned into four groups (n = 10): chamfer finish line with heat‐pressed zirconia reinforced lithium disilicate fixed partial denture (CL), chamfer finish line with monolithic zirconia fixed partial denture (CZ), feather‐edge finish line with heat‐pressed zirconia‐reinforced lithium disilicate fixed partial denture (FL), and feather‐edge finish line with monolithic zirconia fixed partial denture (FZ). After the fabrication of ceramic restoration, micro‐computed tomography was used to evaluate the internal and marginal fits of each fixed partial denture. Data were statistically analyzed with three‐way ANOVA (α = 0.05). Results: There were no significant interactions between preparation type, material type, and tooth type at any of the areas assessed. There was significant difference (p = 0.01) between CZ (59.15 ± 4.6 µm) and FZ (73.6 ± 17.1 µm) groups at the finish line area. Regarding the horizontal marginal discrepancy area, there were significant differences between CZ (62.65 ± 10.5 µm) and FZ (90.05 ± 5.6 µm) groups (p < 0.001), CL (77.45 ± 8.1 µm) and CZ (62.65 ± 10.5 µm) groups (p < 0.001), and FZ (90.05 ± 5.6 µm) and CL (77.45 ± 8.1 µm) groups (p < 0.001). At finish line area, there was a significant difference (p = 0.018) between feather‐edge with canine (72.75 ± 13.3 µm) and chamfer with canine (59.05 ± 5.8 µm); however, there was no significant difference (p = 0.774) between feather‐edge with premolar (69.45 ± 12 µm) and chamfer with premolar (65.1 ± 7.4 µm). Moreover, there was no significant difference (p = 0.886) between feather‐edge with canine and feather‐edge with premolar. Conclusions: The internal and marginal fits of the ceramic fixed partial dentures can be affected by the finish line design and ceramic type. The feather‐edge finish line had a negative impact on the marginal and internal fits of ceramic fixed partial dentures at certain measurement points. Regarding the effect of finish line design on abutment teeth, the difference in fit was only detected at the finish line area of the anterior abutment (canine) with the feather‐edge finish line. [ABSTRACT FROM AUTHOR]

Background: The aim of the study was to investigate the effect of material and occlusal preparation design on the internal fit and marginal gap of endocrowns made of Polyether ether ketone (PEEK) and lithium disilicate. Methods: 32 endocrowns were fabricated on prepared mandibular molars and divided into two groups (n = 16) according to the material. Group L: lithium disilicate and Group P: PEEK. Each group was further subdivided into two subgroups (n = 8) according to the occlusal preparation design: full occlusal coverage (LF and PF) and partial occlusal coverage (LP and PP). Samples were analyzed using microcomputed tomography (µCT) with a voxel size of 6 μm to evaluate internal fit, and an optical microscope was used to evaluate the marginal gap. Data were collected, tabulated, and statistically analyzed. Numerical data were described as mean and standard deviation and compared using the ANOVA test. The level of significance was set at α P ≤ 0.05. Results: All groups' internal fit and marginal gaps values were within the acceptable clinical range. However, the lithium disilicates group recorded statistically significantly higher mean internal gap values than the PEEK groups. Regardless of the material, the difference between the two occlusal designs was not statistically significant in both internal fit and marginal gap records. Conclusion: Within the limitations of this study, PEEK endocrown restorations revealed better internal fit and marginal gap than lithium disilicate endocrown restorations. The marginal and internal fit of both lithium disilicate and PEEK endocrown restorations were within the clinically acceptable range. The occlusal preparation design had no influence on the internal fit and marginal gap of the endocrown restoration. [ABSTRACT FROM AUTHOR]

Objective To evaluate the marginal adaptation of thermoviscous bulk‑fill, preheated, and conventional nanohybrid composite resins in class II cavities. Patients and methods Thirty extracted human sound molars were selected in this in vitro study. Simple class II cavities were prepared using carbide bur. The overall dimensions and depth of cavities were standardized as follows: 4 mm length occlusocervically, 4 mm width buccolingually, and 2 mm depth axially. The teeth were randomly divided into three groups (n = 10 each). Futurabond DC (one-step self-etch adhesive) was applied in all groups. Group 1: cavities were restored with VisCalor bulk composite, group 2: cavities were restored with Grandio composite, group 3: cavities were restored with preheated Grandio composite. The specimens of each group were thermocycled in a thermocycling apparatus by alternating immersion in a water bath at 5 and 55°C with a dwell time of 2 min for 600 thermal cycles. Impressions of the teeth were made and then poured with epoxy resin and replicas were examined under scanning electron microscopy to examine marginal gaps. All data were collected, tabulated, and statistically analyzed. Result The highest percentage of marginal gap length was recorded for group 2, recording 22.93%, while there was no significant difference between group 1 and group 3, recording 13.44 and 13.83%, respectively. One-way analysis of variance test was used to compare the tested groups at a level of significance (P < 0.05). Conclusion The marginal gaps decreased when VisCalor bulk and Grandio composite resins were applied after preheating so preheating composite resins considerably improves marginal adaptation. [ABSTRACT FROM AUTHOR]

Background: This study compared the influence of crystallization on marginal gap adaptation by using computer-aided design and manufacturing (CAD-CAM) for producing monolithic zirconia-reinforced lithium silicate (ZLS) ceramic crowns. Methods: A total of 25 plastic teeth were scanned using a Primescan intra-oral scanner (IOS), and ZLS crowns were ground. For each unit (abutment and crown), the marginal gap was evaluated pre crystallization and post crystallization at four regions of interest through the use of a scanning electron microscope (SEM). To compare the marginal gap between the two groups, a Kolmogorov–Smirnov test performed on the study variables indicated a normal distribution (p > 0.05) followed by paired samples T-tests (α = 0.0005). Results: After crystallization, there were significantly higher circumferential marginal gaps (CMGs) for all four surfaces (distal (p = 0.0005), mesial (p = 0.0005), palatal (p = 0.0005), and buccal (p = 0.0005)). The total mean marginal gap (MMG) revealed a significantly higher result for the post-crystallization group (79.82 ± 7.86 μm) compared to the pre-crystallization group (24.25 ± 5.49 μm). Conclusions: The post-crystallization group showed a significantly higher marginal gap compared to the pre-crystallization group in all parameters, but both groups were in the clinically accepted threshold (® DUO crowns and achieve better mechanical properties but significantly increase the marginal gap.

Purpose: This study evaluated the micro shear bond strength of resin cement to an yttria-stabilized zirconia ceramic and the survival probability of zirconia abutments and crowns after different surface treatments through a fatigue test. Materials and Methods: The study was divided into two parts. For part 1, 95 zirconia disks were divided into five groups (n = 19): control, untreated, airborne particle abrasion with Al2O3 particles before sintering, airborne particle abrasion with Al2O3 particles after sintering, silicatization before sintering, and silicatization after sintering. Three samples of each group were used for evaluation of surface roughness by confocal laser scanning microscopy and afterward were prepared for surface microstructural analysis by scanning electron microscopy. Ten samples of each group were subjected to micro shear bond strength testing, and the interfaces of the remaining six were examined by scanning electron microscopy. In part 2, 70 external hex zirconia abutments and copings were made by computer-aided design/computeraided manufacturing (n = 14). Marginal fit of abutment/coping was measured in a confocal laser scanning microscope. Afterward, a fatigue test was carried out with progressive load of 80 up to 320 N (40 N steps), 5 Hz frequency, and 20,000 cycles at each step. Thermal cycling was simultaneously performed (5°C to 55°C). Results: The group treated after sintering with SiO achieved statistically higher micro shear bond strength (P < .01). Higher failure loads were associated with a combined failure. The surface changes in the group treated with SiO before sintering suggest silica deposition, and there was a lack of homogeneity, which was more evident on the surface of the groups treated before sintering. The marginal gap was higher for the group treated before sintering with SiO (P < .01), and the survival probability of the sets was similar for all tested groups (P = .57). Conclusion: The micro shear bond strength to zirconia was improved after silicatization after sintering, but the survival probability of crown/abutment/implant sets was not affected by different surface treatments. [ABSTRACT FROM AUTHOR]

This systematic review aimed to study the outcomes of CAD-CAM (milled and 3D-printed) interim dental prostheses when compared to conventional ones. The focused question of "In natural teeth, what are the outcomes of CAD-CAM interim FDPs compared to the conventionally-manufactured ones regarding marginal fit, mechanical properties, esthetics, and color stability" was formulated. The systematic search was conducted electronically in the PubMed/MEDLINE, CENTRAL, EMBASE, Web of Science, New York Academy of Medicine Grey Literature Report, and Google Scholar databases by using the MeSH keywords and keywords associated with the focused question and limiting articles to those published between 2000 and 2022. A manual search was conducted in selected dental journals. The results were analyzed qualitatively and are presented in table format. Of the included studies, 18 studies were in vitro and 1 was a randomized clinical trial. Of the eight studies analyzing the mechanical properties, five studies favored the milled interim restorations, one study favored both 3D-printed and milled interim restorations, and two studies reported better mechanical properties in conventional interim restorations. Among four studies evaluating the marginal discrepancies, two studies favored the marginal fit in milled interim restorations, one study reported a better marginal fit in both milled and 3D-printed interim restorations, and one study found conventional interim restorations have a better marginal fit and smaller marginal discrepancy when compared to both milled and 3D-printed restorations. Among five studies that evaluated both the mechanical properties and marginal fit, 1 study favored 3D-printed interim restorations and four studies favored milled interim restorations over the conventional ones. Two studies analyzing the esthetics outcomes demonstrated better results with milled interim restorations compared to conventional and 3D-printed interim restorations in terms of their color stabilities. The risk of bias was low for all the studies reviewed. The high level of heterogeneity within the studies excluded meta-analysis. Most of the studies favored the milled interim restorations over the 3D-printed and conventional restorations. The results suggested that milled interim restorations offer a better marginal fit, higher mechanical properties, and better esthetic outcomes in terms of color stabilities. [ABSTRACT FROM AUTHOR]

Since there are no data in the literature regarding the comparison of the marginal adaptation of hydraulic sealers when used with a single-cone technique or through thermomechanical compaction, this study aimed to evaluate the behavior of four different endodontic sealers used with the two above-mentioned obturation techniques by evaluating the marginal gap existing between the obturation materials and the dentinal walls through scanning electron microscopy. Given this objective, a total of 104 single-rooted, straight canal teeth were selected and divided into four subgroups according to the selected endodontic sealer ((AH) Plus Bioceramic Sealer (AHP), EndoSequence BC Sealer HiFlow (ES), C-Root SP (CR), and GuttaFlow Bioseal (GF)). Each tooth was decoronated and instrumented with the HyFlex EDM/CM systematics up to 30.04. After irrigation procedures, the teeth of each subgroup were divided into two groups and obturated according to two different obturation techniques: the single-cone technique (SC) and the thermomechanical compaction technique (TC). After the required sealer setting time, each tooth was sectioned in three parts at 3, 6, and 9 mm from the apex, and each section was observed with a scanning electron microscope. The marginal gap of each sample was measured using G* Power Software v3.1, and the statistical analysis was performed using the Kruskal–Wallis test, followed by a post hoc Dunn's test. Results showed that there were not any statistically significant differences in terms of the marginal gap between the two different above-mentioned obturation techniques for each sealer, except for the middle third of root canals, where a statistically significant difference was found for AHP, ES, and GF sealers. In conclusion, the thermomechanical compaction of hydraulic sealers and gutta-percha guarantees better sealing than the single-cone technique when the root canal shape is not rounded. [ABSTRACT FROM AUTHOR]

Background: This study aimed to evaluate the effect of virtual cement space and restorative materials on the fit of computer-aided design and computer-aided manufacturing (CAD-CAM) endocrowns. Methods: A mandibular first molar tooth model received a butt joint margin endocrown preparation with a 2-mm occlusal thickness. Then, using a 3D-printing system, 120 copies of this prepared die were printed and assigned equally to three groups with different cement space settings (30, 60, and 120 μm) during the chairside CAD design. In the milling process, CAD-based models with a particular space setting were subdivided into four groups (n = 10) and fabricated from different CAD-CAM materials: Vita Suprinity (VS), Celtra Duo (CD), Lava Ultimate (LU), and Grandio blocs (GR). Finally, the endocrowns were stabilized over their corresponding models with siloxane and subjected to micro-computed tomography to measure the fit. Results: The cement space that was predesigned at 30 μm generated the largest marginal discrepancy (from 144.68 ± 22.43 μm to 174.36 ± 22.78 μm), which was significantly different from those at 60 μm and 120 μm (p < 0.001). The combination of VS or CD with a pre-setting cement space of 60 μm and the combination of LU or GR with a cement space of 120 μm showed better agreement between the predesigned and actual measured marginal gap widths. For internal adaptation, only the cement space set to 30 μm exceeded the clinically acceptable threshold (200 μm). Conclusions: The setting of the cement space and restorative material significantly affected the marginal adaptation of CAD-CAM endocrown restorations. Considering the discrepancy between design and reality, different virtual cement spaces should be applied to ceramic and resin composite materials. [ABSTRACT FROM AUTHOR]

The effectiveness of a universal adhesive applied in different application modes for the preparation of Class V composite restorations was evaluated both clinically and by quantitative marginal analysis (QMA). In each of the 22 patients, four non-carious cervical lesions (NCCL) were restored with Filtek™ Supreme XTE (3M). The adhesive Scotchbond™ Universal (SBU, 3M) was applied in self-etch (SE), selective-enamel-etch (SEE) or etch-and-rinse (ER) modes. The etch-and-rinse adhesive OptiBond™ FL (OFL, Kerr) served as a control. The restorations were clinically evaluated (FDI criteria) after 14 days (BL), 6, 12, 24, and 36 months. Additionally, QMA was conducted on all restorations of 11 randomly selected patients. The FDI criteria and marginal gap were statistically compared between the groups at each recall as well as for the time periods between recalls. The cumulative failure rate was non-significantly higher in the OFL group when compared to all of the SBU groups. Marginal adaptation in the OFL and SBU-SE/ER groups was significantly decreased (BL-36 m, p: 0.004) in comparison to the SBU-SEE group (BL-36 m, p: 0.063). More marginal gaps were found in the OFL group than in the SBU-SEE (BL to 36 m, p: 0.063–0.003) and SBU-ER (24/36 m, p: 0.066/0.005) groups as well as in the SBU-SE group when compared to the SBU-SEE (12–36 m, pi ≤ 0.016) and SBU-ER (24/36 m, p: 0.055/0.001) groups. SBU-SEE performed most effectively. The clinical evaluation and QMA corresponded, yet QMA detected group differences earliest after 6 months and is thus a valuable extension to clinical evaluations. [ABSTRACT FROM AUTHOR]

This work evaluates the internal and marginal adaptation of implant-assisted overdenture cobalt–chromium (Co–Cr) bars manufactured using conventional as well as CAD/CAM subtractive and selective laser melting (SLM) utilizing two scanning techniques. Methods: An edentulous study model containing four dental implants placed at teeth sites 36, 33, 43, and 46 was used. The study cast was scanned and compared to the virtual casts developed from two scanning techniques, straight and zigzag motion, using the in silico superimposition process. Then, conventional techniques were used to produce full-arch bars that were compared to the bars fabricated using the two scanning techniques and CAD/CAM subtractive and additive techniques. Results: The conventional impression and casting techniques had the smallest marginal gap among the groups (P -value < 0.05). The CAD/CAM subtractive milling techniques in groups II and III had significantly smaller marginal gaps than SLM technique used in groups IV and V (P -value < 0.05). The analysis of the internal gap within each group showed statistically significant differences between different implant sites in all groups (P -value < 0.001), except when using the conventional impression and casting techniques in group I (P -value = 0.20). Conclusion: The conventional impression and fabrication techniques were better than the digital impression and CAD/CAM subtractive and additive techniques for the fabrication of full-arch bars. However, both straight and zigzag scanning techniques and the CAD/CAM subtractive technique had marginal and internal gaps that were within clinically accepted ranges, and the SLM was found to be unsuitable for long-span framework fabrication with either scanning technique used. [ABSTRACT FROM AUTHOR]

Objectives: This study compared the accuracy of seven intraoral scanners (IOS) by the virtual-fit method., Methods: Four maxillary arches with tooth abutments were scanned with an industrial reference scanner (n=1) and by Aoralscan3, EmeraldS, Helios600, Lumina, Mediti700, Primescan, and Trios5 IOSs (each n=12). Two complete-arch fixed frameworks were designed on each IOS scan with a 70 µm (group 70) and a 90 µm internal cement space (group 70+20, additional 20 µm at the margin). The virtual-fit method was comprised of superimposing the framework designs onto the reference scan using a non-penetrating algorithm simulating the clinical try-in. Internal and marginal gaps were measured. Precision was estimated by the mean absolute errors (MAE)., Results: In group 70, Mediti700 (43 µm), Primescan (42 µm), and EmeraldS were in the best homogenous subset for the marginal gap, followed by the Lumina (67 µm), Aoralscan3 (70 µm), and Trios5 (70 µm), whereas Helios600 (118 µm) was in the third subset. Based on the MAE at the margin, Mediti700, Trios5, and EmeraldS were in the first-best homogenous subset, followed by Primescan. Lumina and Helios600 were in the third subset, and Aoralscan3 was in the fourth subset. In group 70+20, the marginal gap was significantly decreased for Lumina and Aoralscan3, whereas MAE significantly decreased for EmeraldS and Aoralscan3. The rank of IOSs was similar for the internal gap., Conclusion: EmeraldS, Mediti700, Primescan, and Trios5 meet the marginal and internal fit criteria for fixed tooth-borne complete arch restorations. Increasing the cement space during design could enhance restoration fit., Clinical Significance: The virtual-fit alignment method can effectively evaluate the accuracy of different intraoral scanners, offering valuable clinical guidance for distinguishing among them. Recent software and hardware versions of long-standing IOS manufacturers are suitable for fabricating complete arch restoration., 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.)

This study analyzes the evidence of the marginal discrepancy and internal adaptation of copings fabricated using three types of resin patterns with subtractive (milling) and additive technology (3D printing), as it is not widely reported. Working casts (n = 15) were scanned and patterns were completed using computer-aided designing (CAD). Resin patterns were fabricated using the designed data and divided into three groups according to the method of fabrication of patterns: subtractive technology–CAD milled polymethyl methacrylate resin (Group-PMMA), additive technology [digital light processing (DLP) technique]–acrylonitrile–butadiene–styrene (ABS) patterns (Group-ABS), and polylactic acid (PLA) patterns (Group-PLA). Resin patterns were casted with Cobalt–Chromium (Co–Cr) alloy (lost wax technique). Internal and marginal gaps of the metal copings were analyzed with the replica technique under optical microscope. The Kruskal–Wallis test was used to compare values among the groups, and post hoc multiple tests confirmed the specific differences within the groups. The median marginal gap was least for CAD milled resin patterns, followed by PLA printed resin patterns and ABS printed resin patterns. There were significant differences between Group-PMMA and Group-PLA and Group-ABS (p = 0.0001). There was no significant difference between Group-PLA and Group-ABS (p = 0.899). The median internal gap was least for metal copings fabricated from Group-PLA, followed by Group-ABS and Group-PMMA. The differences were not statistically significant (p = 0.638) for the internal gap. Full metal Co–Cr copings fabricated from the milled PMMA group had a better marginal fit, followed by the PLA and ABS printed groups. Copings fabricated with the PLA printed group had the best internal fit, though the values were statistically insignificant between the groups. [ABSTRACT FROM AUTHOR]

Background: The purpose of this study was to compare the marginal gaps of sequentially milled lithium disilicate (LDS) crowns using two different milling units. Methods: One lower left first molar typodont tooth prepared for an LDS crown by an undergraduate student in a simulation clinic was selected. The crown preparation was scanned by a TRIOS 3 scanner and twelve LDS crowns milled by an E4D (E4DM) and a Sirona inLab MC X5 (MCX5) milling unit using identical settings. The crowns were seated onto the original crown preparation and three vertical marginal gap measurements were taken at four locations (mid‐buccal, mid‐lingual, mid‐mesial and mid‐distal) using a stereomicroscope. The mean marginal gap (MMG) was calculated for each individual tooth surface and each crown. Results: The MMG for the E4DM (100.40 μm) was not significantly different to the MCX5 (101.08 μm) milling unit (P = 0.8809). In both units, there was a statistically significant trend of increasing MMG with sequentially milled crowns using the same burs (E4DM P = 0.0133; MCX5 P = 0.0240). Conclusions: The E4DM and MCX5 milling units produced LDS crowns with similar MMG's and within a clinically acceptable range but with a trend of increasing MMG when analysed sequentially. © 2022 Australian Dental Association [ABSTRACT FROM AUTHOR]

Background: The aim of this study is to investigate the impact of ceramic material and preparation design on the marginal fit of endocrown restorations. Methods: Forty endocrown restorations were CAD/CAM-fabricated for forty extracted maxillary first premolar teeth. Samples were divided into two groups (n = 20) according to the ceramic materials used: Celtra Duo and Vita Enamic. Each group was divided into two subgroups (n = 10) according to the preparation design: with no intraradicular extension and with 3 mm intraradicular extension. The marginal gap was examined using a digital microscope. Results: Celtra Duo without intraradicular extension recorded the least mean marginal gap (7.74 ± 1.55 µm), while Group Celtra Duo with 3 mm intraradicular extension recorded the highest mean marginal gap (29.54 ± 6.32 µm). Group Vita Enamic recorded a lesser marginal gap (18.03 ± 12.11 µm) than group CD (Celtra Duo) (18.64 ± 12.05 µm). There is a statistically non-significant difference between the two groups of materials (p = 0.873). There is a statistically significant difference between the two tested preparation designs (p < 0.001). Conclusion: All groups recorded a marginal gap within clinically accepted values. Material selection may influence the fitting of restorations. Intraradicular extension for endocrown restorations adversely affects the marginal fit, however, the marginal gap is still within the clinically accepted range. [ABSTRACT FROM AUTHOR]

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Introduction: Marginal misfit in screw-retained implant restorations when screwing torque leads to deformation of superstructure and formation of strain in the lower bone. Therefore, decreasing the marginal gap is considered one of the therapeutic goals in the fabrication of screw-retained implant-supported prostheses. This study aimed to investigate the effect of four framework construction techniques on the marginal accuracy of screw-retained implant-supported fixed partial restorations. Materials and Methods: The main model was an acrylic block with two implants that simulated 3-unit implant-supported screw-retained prostheses with a second premolar pontic. Standard abutments for screw veneers on implants were tightened with 25 Ncm torque. In this study, six metal frameworks were fabricated using four techniques, namely integrated casting, soldering, double casting, and soft metal CAD/CAM cobalt-chrome on the abutments and the marginal gap in the anterior and posterior bases was evaluated by the standard one screw test method. In the next step, the occlusal screw of both pins was tightened and the marginal gap was re-measured (definite fit). The mean scores of marginal gap values ​​were calculated in terms of passive fit and definitive fit. Finally, the results were assessed using one-way ANOVA and Tamhane post-hoc tests (p < 0.05). Results: The mean scores of the marginal gap were significantly different among the four studied groups regarding both passive fit and definitive fit (p < 0.001). According to the Tamhane post hoc test in the passive fit condition, the mean scores of marginal gap of CAD/CAM group were significantly lower than those in the other groups (p < 0.001). Conclusion: The passivity of the screw-retained fixed implant frameworks was influenced by the manufacturing technique. It was revealed that CAD/CAM method exhibited the best passivity, compared to three conventional studied methods.

Objective: To compare the marginal and internal adaptation of endocrowns produced using conventional technique, digital technique, and combination (cast digitization) techniques using microcomputed tomography (micro‐CT). Materials and Methods: Ten freshly extracted human mandibular molar teeth were prepared for all‐ceramic endocrowns. A total of 40 Lithium Disilicate (IPS e.max) endocrowns were fabricated and grouped according to the impression and production technique to four groups: Group (CO): Conventional impression/heat pressed endocrowns (n = 10), Group (CAD): Direct scanning of teeth/CAD‐CAM endocrowns (n = 10), Group (COMIO): Combination; Cast digitization using Intraoral scanner/CAD‐CAM endocrowns (n = 10), Group (COML): Combination; Cast digitization using laboratory scanner/CAD‐CAM endocrowns (n = 10). Micro‐computed tomography was used to measure the marginal and internal gaps in 11 predetermined sites. Mean marginal and internal gaps were compared using analysis of variance and Scheffe's post hoc test. Results: CO, CAD, COMIO, and COML groups showed significant differences in the mean marginal gap (150 ± 35 μm, 120 ± 27 μm, 110 ± 24 μm, 120 ± 29 μm, respectively p = 0.013), gap at line angle (280 ± 70 μm, 130 ± 37 μm, 140 ± 54 μm, 130 ± 33 μm, respectively, p < 0.001), gap at cavity wall (210 ± 76 μm, 140 ± 43 μm, 140 ± 52 μm, 150 ± 44 μm, respectively, p = 0.010) and gap at pulpal floor (500 ± 150 μm, 240 ± 58 μm, 260 ± 59 μm, 240 ± 64 μm, respectively, p < 0.001). Conclusion: Digitally fabricated endocrowns showed superior marginal and internal fit compared to the conventionally fabricated endocrowns. Clinical Significance: Marginal and internal adaptation are detrimental factors for the success and survival of dental restorations including endocrowns. When compared with the conventional impressions and conventional production techniques, Digital workflow is more predictable and reliable as it reduces errors and improves the accuracy of fit. [ABSTRACT FROM AUTHOR]

Background: The purpose of this study was to compare the marginal gaps of CAD/CAM lithium disilicate (LDS) crowns constructed using three different scanner and milling unit combinations. Methods: Twenty‐four Columbia model lower left molars were prepared for LDS crowns by undergraduate students in a simulated environment. One LDS crown was constructed for each crown preparation using each of the following intraoral scanner/milling unit combinations: TRIOS 3 scanner/E4D milling unit (TRIO/E4DM); TRIOS 3 scanner/Sirona inLab MC X5 milling unit (TRIO/MCX5); E4D scanner/E4D milling unit (E4DS/E4DM). The crowns were seated onto the original crown preparations and three vertical marginal gap measurements taken at four locations (mid‐buccal, mid‐lingual, mid‐mesial and mid‐distal) using a stereomicroscope. The mean marginal gap (MMG) was calculated for each crown and each individual tooth surface. Results: The TRIO/MCX5 scanner/milling unit combination produced the smallest MMG of 63.73 ± 47.38 μm followed by E4DS/E4DM (88.64 ± 106.51 μm) and TRIO/E4DM (107.41 ± 76.47 μm). There was a significant effect of milling unit (p < 0.0001) on MMG but no significant effect of scanner (p = 0.070) or location (p = 0.182). Conclusions: The newer scanner/milling unit combination produced LDS crowns with the smallest MMG. All scanner/milling unit combinations produced LDS crowns within a clinically acceptable MMG. [ABSTRACT FROM AUTHOR]

This study evaluated the 3-dimensional (3D) fit of self-glazed zirconia monolithic crowns fabricated by wet deposition, in comparison with milled zirconia and lithium disilicate monolithic crowns. Dual-scan protocol was used to assess the fit of crowns. Root mean squares (RMS) and uniformity index (UI) were calculated to describe the gap size and uniformity. The self-glazed zirconia crowns had significantly lower RMS values for the gaps at axial wall and transition regions than the milled zirconia crowns, and for the gaps at occlusal region than both milled crowns. All 3 types of crowns had comparable RMS values for the gaps at marginal and chamfer regions and comparable UI values for both marginal and internal gaps. The 3D fit of the self-glazed zirconia monolithic crowns was clinically acceptable and they exhibited better fit at occlusal region than the milled crowns. [ABSTRACT FROM AUTHOR]

Background: The master cast is the gold standard for the control and eventual adjustment of restorations produced by conventional procedures. Some digital workflow bypasses the master cast and relies completely on the precision of the CAD/CAM restoration. Aim: To examine the reproducibility of the margins of CAD/CAM restorations generated from a single digital scan. Also, to check the readiness of these restorations for delivery directly after fabrication without adjustment on a master cast and thereby eliminate the need for the master cast. Methods: A total of 18 metal substructures made from cobalt chrome alloy were fabricated utilizing a single STL file. The circumference was divided into eight zones. The vertical marginal discrepancy (VMD) was measured at each zone of each metal substructure, with optical microscopy at ×200 magnification. Results: Measurements of vertical marginal discrepancy were in a range of (-94: 300) with a mean of 62 ± 60 mm. A one-way ANOVA test revealed that the mean VMD is significantly different among the 18 substructures (F17, 1,134 = 63.948, p < 0.001). Conclusion: Although all the received substructures were fabricated from the same scan file, they were not identical and varied widely, and they were going outside the acceptable range in some zones. Within the limitations of this study, the marginal fit can be improved by extraoral adjustments on the master cast. Thus, skipping the master cast deprives the dentist of delivering a restoration of higher quality. [ABSTRACT FROM AUTHOR]

Introduction: Thiourethane addition to methacrylate of resin cements improves properties of flexural strength, toughness modulus, and fracture toughness. The aim of this study was to evaluate the effect of experimental silanes based on thiourethane in the adhesion of fiberglass posts to the root canal submitted to thermal and mechanical cycling. Materials and Methods: Two oligomers were synthesized with catalytic amounts of triethylamine. Multifunctional thiol–pentaerythritol tetra-3-mercaptopropionate was combined with difunctional isocyanates – 1,6-hexanedioldiissocyante (aliphatic) or 1,3-bis (1-isocyanato-1-methylethyl) benzene (aromatic). Human dental root canals were treated with conventional and experimental silanes, establishing six experimental groups (n = 10) endodontically rehabilitated with fiberglass posts. The specimens were submitted to 1.2 x 106 mechanical cycles and 500 thermal cycles (5°C and 55°C). One slice from each root region (cervical, middle, and apical) was submitted to the push-out bond test, and the fracture pattern evaluated. Scanning electron microscopy micrographs were obtained from the marginal gaps occurred in the adhesive interfaces. Data were analyzed with two-way ANOVA followed by Tukey's test at α = 0.05 confidence level. Results: Conventional and experimental silanes improved bond strength (P < 0.001) with similar values among the root regions (P = 0.199), decreased the occurrence of adhesive failures in dentin-cement bond, and increased the cohesive failures in dentin and the mixed failures. The marginal gaps showed in scanning electron microscopy micrographs were similar, except for the Angelus conventional silane, showing greater slit. Conclusions: Conventional and experimental silanes provided greater adhesive strength, reduced dentin-cement failures, and the marginal gaps were similar, except for the control group Angelus, showing greater slit.

Aim: This study aimed to evaluate the effect of polymerization with either a monowave (MW) or a polywave (PW) light-curing unit (LCU) on the degree of conversion (DC) and marginal adaptation following thermomechanical aging of an ormocer bulk-fill resin composite (RC) (Admira fusion X-tra Bulk Fill – AB), a methacrylate-based bulk-fill RC (Tetric N-Ceram Bulk Fill – TB) and a conventional RC (Tetric N-Ceram – TC). Methods: DC was assessed in five samples of each RC using Fourier transform infrared spectroscopy. For determination of marginal adaptation, standard preparations were made in 60 bovine incisors, divided into three groups, according to the RC. The bulk-fill RC was inserted in a single increment of 4 mm. In contrast, the conventional RC was inserted in three increments. Marginal gap was evaluated after thermomechanical aging. Data were analyzed using a two-way analysis of variance (ANOVA) and Tukey’s tests for multiple comparisons (α = 0.05). Results: The two-way ANOVA showed a significant effect (p