Marginal integrity and physicomechanical properties of a thermoviscous and regular bulk-fill resin composites.

OBJECTIVES: To evaluate the marginal integrity (MI%) and to characterize specific properties of a thermoviscous bulk-fill resin composite, two regular bulk-fill resin composites, and a non-bulk-fill resin composite. MATERIALS AND METHODS: VisCalor bulk (VBF), Filtek One Bulk Fill (OBF), and Aura Bulk Fill (ABF) were evaluated. Filtek Z250 XT (ZXT) was used as non-bulk-fill control. MI% was evaluated in standardized cylindrical cavities restored with the composites by using a 3D laser confocal microscope. The following properties were characterized: volumetric polymerization shrinkage (VS%), polymerization shrinkage stress (Pss), degree of conversion (DC%), microhardness (KHN), flexural strength (FS), and elastic modulus (EM). Data were analyzed by one-way and two-way ANOVA, and Tukey HSD post-hoc test (α = 0.05). RESULTS: VBF presented the highest MI% and the lowest VS% and Pss (p < 0.05). DC% ranged from 59.4% (OBF) to 71.0% (ZXT). ZXT and VBF presented similar and highest KHN than OBF and ABF (p < 0.05). ABF presented the lowest FS (p < 0.05). EM ranged from 5.5 GPa to 7.7 GPa, with the values of ZXT and VBF being similar and statistically higher than those of OBF and ABF (p < 0.05). CONCLUSIONS: Thermoviscous technology employed by VisCalor bulk was able to improve its mechanical behavior comparatively to regular bulk-fill resin composites and to contribute to a better marginal integrity in restorations built up in cylindrical cavities with similar geometry to a class I cavity as well. Although presenting overall better physicomechanical properties, Z250 XT presented the worst MI%. CLINICAL RELEVANCE: The marginal integrity, which is pivotal for the success of resin composite restorations, could be improved using VisCalor bulk-fill. The worst MI% presented by Z250 XT reinforces that non-bulk-fill resin composites shall not be bulk-inserted in the cavity to be restored.

Evaluation of vertical marginal discrepancy and load-to-failure of monolithic zirconia and lithium disilicate laminate veneers manufactured in different thicknesses.

OBJECTIVES: This study aimed to evaluate the feasibility of monolithic zirconia laminate veneers (MZLV) compared to lithium disilicate laminate veneers (LDLV). MATERIALS AND METHODS: Sixty resin replicas, each prepared with depths of 0.5 mm, 0.7 mm, and 1 mm, were produced using a 3D printer from acrylic teeth. Laminate veneers of these thicknesses were milled from pre-sintered monolithic zirconia (3rd generation) and lithium disilicate blocks. The intaglio surface of MZLV was treated with air abrasion using 110 µm diameter silica-modified aluminium oxide particles and ceramic primer, while LDLV was etched with etchant gel and treated with the ceramic primer before cementation with resin cement. Vertical marginal discrepancy (VMD) was assessed using a stereomicroscope, and a load-to-failure test was conducted using a universal testing machine. Failure modes were evaluated macroscopically on fractured surfaces. Data were analysed statistically using Two-way ANOVA and Bonferroni correction (α = 0.05). RESULTS: LDLV samples exhibited significantly larger VMD compared to MZLV samples across all thicknesses, especially in cervical, palatal, and mean data. Within the LDLV group, load-to-fracture values for 0.7 mm and 1.0 mm thicknesses were similar, whereas for 0.5 mm thickness, it was significantly lower. In the MZLV group, load-to-fracture values were lower for 0.7 mm and 1.0 mm thicknesses compared to LDLV, but higher for 0.5 mm thickness. CONCLUSIONS: Material choice and restoration thickness significantly influence laminate veneer restorations' success. MZLV generally exhibits superior vertical marginal fit compared to LDLV, with varying load-to-failure values across different thicknesses. Clinical management of debonding in MZLV is simpler compared to restoration fracture in LDLV. CLINICAL RELEVANCE: Considering clinical factors, MZLV may be a preferable option to LDLV for this restoration with the thickness of 0.5 mm.

Comparative evaluation of retention, marginal adaptation and marginal discoloration of hydrophilic and hydrophobic pit and fissure sealants: A split-mouth randomized controlled trial.

BACKGROUND: Pit and fissure sealants are the most commonly used preventive measure against caries in permanent molars. Advancements in dental materials have led to the development of hydrophilic sealants. However, their clinical efficacy must be evaluated and compared with that of conventional hydrophobic sealants. OBJECTIVES: This study aimed to clinically evaluate and compare the retention, marginal adaptation and marginal discoloration of hydrophilic and hydrophobic pit and fissure sealants over a 12-month follow-up period. MATERIAL AND METHODS: The study was a split-mouth, double-blind, randomized controlled trial. A sample size calculation was performed, and 120 first permanent molars (60 in each group) were selected for inclusion in the study. According to the split-mouth design, the sample was randomly divided into 2 groups. Group A was treated with a hydrophilic sealant (UltraSeal® XT Hydro), while Group B was treated with a hydrophobic sealant (Conseal F). The sealants in both groups were applied in accordance with the manufacturer's instructions by a single operator. The sealants were evaluated clinically using visual and tactile methods by 2 independent examiners who were blinded to the procedure in accordance with the modified United States Public Health Service (USPHS) clinical rating system at placement and at 1, 3, 6, and 12 months. RESULTS: After 12 months of follow-up, the Conseal F sealant showed significantly better retention (p = 0.001), marginal adaptation (p = 0.023) and reduced marginal discoloration (p = 0.004) in comparison to the UltraSeal XT Hydro sealant. CONCLUSIONS: The Conseal F (hydrophobic) sealant demonstrated superior retention, marginal adaptation and marginal discoloration compared to the UltraSeal XT Hydro (hydrophilic) sealant.

Fracture resistance, marginal and internal adaptation of innovative 3D-printed graded structure crown using a 3D jet printing technology.

PURPOSE: This in vitro study aimed to create a graded structured dental crown using 3D printing technology and investigate the fracture resistance and the adaptation of this new design. MATERIALS AND METHODS: A dental crown with a uniform thickness of 1.5 mm was designed, and the exported stereolithography file (STL) was used to manufacture 30 crowns in three groups (n = 10), solid (SC), bilayer (BL), and multilayer (ML) crowns using  3D jet printing technology. Marginal and internal gaps were measured using the silicone replica technique. Crowns were then luted to a resin die using a temporary luting agent and the fracture resistance was measured using a universal testing machine. One-way ANOVA and Tukey post hoc tests were used to compare the fracture resistance and the adaptation of crowns at a significance level of 0.05. RESULTS: Mean marginal and internal gap of the ML group were 80 and 82 mm, respectively; which were significantly (p < 0.05) smaller than BL (203 and 183 mm) and SC (318 and 221 mm) groups. The SC group showed the highest mean load at fracture (2330 N) which was significantly (p < 0.05) higher than the BL (1716 N) and ML (1516 N) groups. CONCLUSION: 3D jet printing technology provides an opportunity to manufacture crowns in a graded structure with various mechanical properties. This study provided an example of graded structured crowns and presented their fracture resistance. SC group had the highest fracture resistance; however, ML had the best marginal and internal adaptation.

Evaluation of colour change, marginal adaptation, fracture strength, and failure type in maxillary and mandibular premolar zirconia endo-crowns.

OBJECTIVES: The objective of this in vitro study was to evaluate the effects of different preparation designs on the mean colour change (ΔE*), marginal adaptation, fracture resistance, and fracture types of maxillary and mandibular premolar endocrowns (ECs). METHODOLOGY: A total of 40 extracted maxillary and mandibular premolars were treated endodontically, and each type was subdivided according to the remaining axial height (remaining walls on all surfaces; 2-4 mm) and 2 mm inside the pulp chamber. Specimens were immersed in coffee for 14 days, ΔE* was determined, marginal adaptation was observed, fracture forces test was conducted, and the samples were examined visually at 10× magnification to evaluate failure type and identify fracture origin. The data were entered and analyzed using Statistical Package for Social Sciences, and significance between and within groups was evaluated through ANOVA. The p-value ≤ 0.05 was considered statistically significant. RESULTS: The ΔE* values of the maxillary premolar with 2 mm axial height were the highest (6.8 ± 0.89 units), whereas the lowest value was observed in the mandibular premolar with 4 mm axial height (2.9 ± 0.53 units). Significant differences (p < 0.05) in teeth and design were observed. The marginal adaptation of the mandibular premolar with 4 mm axial height was the highest (30.20 ± 1.53 µm), whereas the lowest marginal adaptation was observed in the maxillary premolar with 2 mm axial height (14.38 ± 0.99 µm), and the difference was statistically significant (p < 0.05). The maximum fracture force was observed in maxillary premolars with 2 mm axial height (2248.15 ± 134.74 N), and no statistically significant difference (p = 0.07) was observed between maxillary and mandibular premolars at 4 mm axial height. CONCLUSION: The recorded ΔE* values of the ECs were within clinically acceptable values or slightly higher, and the marginal adaption values were within acceptable and recommended clinical values in µm. EC preparation with 2 mm axial height in both arches recorded the highest fracture forces. Type III (split fracture) failure was recorded as the highest in the maxillary and mandibular premolar ECs with different axial wall heights.

Comparison of misfit and roughness of CAD-CAM ZrO, selective laser sintered CoCr and preformed Ti implant abutment crowns.

BACKGROUND: Marginal misfit and surface roughness of customized implant abutments is critical for restorative success. However, little is known about the comparison of misfit and surface roughness of CAD-CAM Zirconium oxide (ZrO), selective laser melting (SLM) Cobalt Chrome (CoCr) and preformed abutments. The aim of the study is to investigate the relation of misfit and micro-roughness of selective laser melting (SLM), preformed and CAD-CAM implant abutments. METHODS: Thirty internal connection, endosseous dental implants (Ø 4.0 mm x 10 mm, Dentium) were mounted in Polymethyl methacrylate vertically. Ten preformed Titanium alloy (Ti) abutments with 1 mm soft tissue height and Ø 4.5 mm were included as controls. Ten each of Y-TZP and SLM-CoCr, abutment/crowns were fabricated using CAD-CAM milling (CAD-CAM-ZrO) and SLM techniques. Surface micro-roughness (Ra) of the fabricated implant abutment/crown was evaluated with a 3D optical non-contact microscope. All implant restorations were torqued to implants (30 Ncm) using a Tohnichi BTGE digital torque gauge and were analyzed with Bruker micro-CT (Skyscan 1173) to detect micro-gaps at pre-selected points at implant abutment interface. The Ra and misfit data were compared using ANOVA, Tukey-Kramer, Kruskal-Wallis test and Pearson correlation (p < 0.05). RESULTS: Mean Ra among SLM CoCr abutments [0.88 (0.09) µm] were lower than CAD-CAM-ZrO and higher than preformed Ti abutments. Horizontal misfit among SLM-CoCr [45.43 (9.41) µm] and preformed Ti [36.87 (13.23) µm] abutments was not statistically different (p > 0.05). Misfit was significantly higher in Y-TZP samples compared to SLM-CoCr (p = 0.031) and preformed Ti abutments (p = 0.01). Preformed Ti abutments showed significantly lower misfit compared to SLM-CoCr abutments (p = 0.01). A positive linear correlation was observed between the surface roughness (Ra) and vertical misfit (r = 0.61, p < 0.05). CONCLUSION: SLM CoCr abutments showed rough surface compared to preformed Ti abutments, while horizontal misfit was comparable among SLM-CoCr and preformed abutments. Misfit was significantly greater in Y-TZP abutments, compared to SLM and preformed abutments. SLM abutment fabrication technique needs further improvement to provide better fit and surface topography.

Complete-arch accuracy of seven intraoral scanners measured by the virtual-fit method.

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.

Tissue surface adaptation and retention of digital obturator after one year of use.

BACKGROUND: Effect of aging on tissue adaptability and retention of digital obturator is still under investigation. METHODS: A maxillary Armany (class I) epoxy reference model was scanned to fabricate digital obturator fabricated from milled Co-Cr framework and 3D printed bulb. A color map of the scanned reference and digital obturator was made using Geomagic software to evaluate the accuracy of fit before and after cyclic loading using ROBOTA chewing simulator at 37,500, 75,000 and 150,000 cycles to simulate clinically 3-, 6- and 12-months chewing condition. Insertion-removal condition simulating the placement and removal of the obturator was done using repeated 360, 720 and 1440 cycles and retention was evaluated before and after the repeated cycles. Data were collected, tabulated and statistically analyzed using Statistical Package for Social Sciences (IBM SPSS Statistics 26). Student t-test and multi variable ANOVA test were used to detect significance. P-value < 0.05 was considered significant difference. RESULTS: For retention test: There was a significant difference between baseline and 3, 6 and12 months. For the tissue surface adaptation test: There was significant difference at all measured areas (P-value < 0.05) before and after application of load. CONCLUSION: digitally designed and fabricated obturator was highly retentive and has excellent tissue surface adaptation upon fabrication, After application of load; reduction of retention and lack of tissue adaptation were resulted. THE CLINICAL IMPLICATION: of this manuscript is that digital obturator can be used successfully with the shortcomings of loosening retention and adaptation afterwhile. So, clinical trials should investigate the clinical acceptance of these shortcomings.

Marginal integrity of prototype bioactive glass-doped resin composites in class II cavities.

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.

An In Vitro Study of Retention and Marginal Adaptation of Endocrowns With Different Intracoronal Depths.

BACKGROUND: Marginal adaptation and retention of endocrowns are crucial for the success and survival of endocrowns. This study aimed to investigate the effect of different materials and intracoronal depth on the retention and marginal adaptation of CAD/CAM fabricated all-ceramic endocrowns. METHODS: Thirty-six mandibular premolar teeth with an average surface area of 64.49 mm2 were prepared to receive CAM/CAM fabricated endocrowns. Samples were divided randomly and equally into groups of lithium disilicate with 2 mm intracoronal depth (LD2), lithium disilicate with 4 mm intracoronal depth (LD4), polymer infiltrated ceramic network with 2 mm intracoronal depth (PICN2) and polymer infiltrated ceramic network with 4 mm intracoronal depth (PICN4). All endocrowns were cemented using ParaCore resin cement with 14N pressure and cured for 20 seconds. Fifty measurements of absolute marginal discrepancy (AMD) were done using a stereomicroscope after cementation. After 24 hours, all samples were subjected to thermocycling before the retention test. This involved using a universal testing machine with a crosshead speed of 0.5 mm/min and applying a load of 500N. The maximum force to detach the crown was recorded in newtons and the mode of failure was identified. RESULTS: Two-way ANOVA revealed that the AMD for PICN was statistically significantly better than lithium disilicate (p=0.01). No statistically significant difference was detected in the AMD between the two intracoronal depths (p=0.72). PICN and endocrowns with 4 mm intracoronal depth had statistically significant better retention (p<0.05). 72.22% of the sample suffered from cohesive failures and 10 LD endocrowns suffered adhesive failures. CONCLUSIONS: Within the limitations of this study, we found that different materials and intracoronal depths can indeed influence the retention of CAD/CAM fabricated endocrowns. Based on the controlled setting findings, PICN was found to have better retention and better marginal adaptation than similar lithium disilicate premolar endocrowns.

Impact of Cut-out-rescan and Data Exchange by Over-scanning Techniques on Marginal Fit of CAD/CAM Lithium Disilicate Crowns.

OBJECTIVE: Evaluate the impact of adjustment procedures - cut-out-rescan (COR) and data exchange by over-scanning (DEOS) techniques - through CAD/CAM software on the marginal fit outcome of ceramic crowns. METHODS AND MATERIALS: Twenty-eight de-identified teeth were adapted in a mandibular typodont set. Tooth #19 was prepared for a lithium disilicate crown and seven groups, G0 to G6 (n=10), were created based on the rescanned areas (mesial and/or buccal) on the typodont using an intraoral scanner through COR or DEOS techniques. A digital workflow was used to design and mill 70 crowns according to the groups. Each crown was temporarily cemented on tooth #19 and scanned with micro-computed tomography to measure the marginal fit. The data were analyzed statistically by the Kruskal-Wallis test followed by the Mann-Whitney test to compare the groups pairwise as a post-hoc (α=0.05). RESULTS: Statistically significant differences were found for vertical misfit (µm) between the groups for Marginal Gap Buccal (MGB) and Marginal Gap Mesial (MGM) (p=0.003 and p=0.029, respectively). No significant difference was found for Finish Line Buccal (FLB) and Finish Line Mesial (FLM) (p=0.062 and p=0.092, respectively). G3 (COR buccal and mesial) had the highest MGB (57.75 µm), statistically different from all other groups. G4 (DEOS buccal) (41.60 µm) was different from G6 (DEOS buccal and mesial) (44.21 µm) (p=0.023). For MGM, G0 (control) (53.96 µm) was different from G5 (DEOS mesial) (45.76 µm) and G6 (DEOS buccal and mesial) (48.56 vm) (p=0.013 and p=0.041, respectively) and G2 (COR mesial) (58.43 µm) was different from G5 (DEOS mesial) (45.76 µm) (p=0.016). CONCLUSIONS: Despite a statistically significant difference in certain groups for both techniques, COR and DEOS techniques are viable options for image editing during acquisition. Lithium disilicate crowns can be produced with satisfactory marginal gap values utilizing a chairside CAD/CAM system.

Evaluation of fracture resistance and marginal fit of implant-supported interim crowns fabricated by conventional, additive and subtractive methods.

BACKGROUND: Interim crowns are utilized for restoring implants during and after the process of osseointegration. However, studies on adaptation and fracture strength of implant-supported interim crowns are rare. AIM OF THE STUDY: The aim of this in vitro study is evaluating marginal fit and fracture resistance of conventional, subtractive, and additive methods of fabricating implant-supported interim crowns. MATERIALS AND METHODS: An implant was placed in an epoxy resin model with a missing first molar. A scan body was attached, and scanned with an intraoral scanner (IOS), the STL file was used to fabricate eighteen master models with standardized implant digital analogue spaces. The digital analogues and their corresponding abutments were attached to the master models and scanned with the IOS, the STL files were used to fabricate eighteen crowns using three different techniques (n = 6): conventional (CR); from Autopolymerizing composite resin, subtractive (SM); milled from PMMA resin blanks, and additive (AM); from 3D printed resin material. The crowns were fitted and cemented on their corresponding abutments and subjected to cyclic loading and thermocycling. The marginal fit was evaluated using a stereomicroscope. The crowns were then loaded until fractured in a universal testing machine. The Shapiro-Wilk and the Kolmogorov-Smirnov tests revealed that data of Marginal gap was non-parametric. Kruskal-Wallis test followed by the Dunn test was used (α = 0.05). While data of Fracture resistance test was parametric. ANOVA (F-test) was used followed by the Tukey test (α = 0.05). RESULTS: For marginal gap, a significant difference was shown between the study groups (P = .001) according to Kruskal-Wallis test. Groups SM and AM had significantly lower marginal gap values compared to group CR (P = .003). No significant difference was found between groups SM and AM (P = .994). For fracture resistance, One-way ANOVA revealed a significant difference in fracture resistance between study groups (P < .001). Group SM had significantly higher fracture strength followed by group AM and group CR (P = .001). CONCLUSIONS: Group SM and AM showed better marginal adaptation than group CR. Group SM showed superior fracture resistance compared to other groups. All study groups showed acceptable marginal gap and fracture resistance.

Influence of various fabrication techniques and porcelain firing on the accuracy of metal-ceramic crowns.

BACKGROUND: The fit of a metal-ceramic restoration is essential to its long-term durability. Regarding marginal and internal fit, there is not enough information about the technologies used in the production of metal-ceramic restorations. The aim of this in vitro study is to compare, both before and after porcelain firing, the marginal, axial, axio-occlusal, and occlusal fit of metal-ceramic restorations manufactured using casting, additive or subtractive computer-aided design, and computer-aided manufacturing techniques (CAD/CAM). METHODS: CAD/CAM were used to create 50 prepared maxillary first molar-shaped Co-Cr die models, which were randomly divided into 5 groups (n = 10). Cobalt-chrome copings were produced by casting (C), hard metal milling (HM), soft metal milling (SM), selective laser melting (SLM), and selective laser sintering (SLS) techniques. Before and after porcelain firing, discrepancies of the copings were measured using the silicone replica technique. The data obtained by measurements with a stereomicroscope at x80 magnification were analyzed statistically in the SPSS program. The ROBUST three-way analysis of variance (ANOVA) method was used to compare the discrepancy values. RESULTS: There were statistically significant differences among fabrication methods (P < .001). The HM method showed the highest discrepancy (90.1 µm), and the C (63 µm) method showed the lowest discrepancy in terms of the die model- crown fit. The C, SLS, and SM methods (63 µm; 61.6 µm; 67.7 µm) were statistically similar (P > .001). The highest discrepancy was observed on the occlusal area (87.1 µm), and the lowest discrepancy was observed on the axial area (47.7 µm) of the coping. Porcelain firing had a decrease in the discrepancy values (P = .001). CONCLUSION: All CAD/CAM techniques are appropriate for clinical use; selective laser sintering and soft milling can be the more recommended methods for the compatibility of metal-porcelain restorations, as they have lower discrepancy values than the SLM and HM methods.

A comparative evaluation of marginal fit and microleakage of computer-aided design/computer-aided manufacturing-milled zirconia and prefabricated posterior occlusal veneers: An in vitrostudy.

AIMS: The aim of this study was to compare the marginal fit of prefabricated occlusal veneers with computer-aided design/computer-aided manufacturing (CAD-CAM)-milled zirconia occlusal veneers in the posterior teeth. SETTINGS AND DESIGN: Forty extracted human maxillary premolars were divided into two groups of 20 each. Group 1 was prepared to receive prefabricated occlusal veneers, and Group 2 was prepared to receive CAD-CAM-milled zirconia occlusal veneers. MATERIALS AND METHODS: Prefabricated samples (Edelweiss) were selected for Group 1, whereas for Group 2, the tooth preparations were scanned, and occlusal veneers were fabricated using Exocad designing software and milling machine. After luting, both the groups were submerged in dye, sectioned, and evaluated for marginal fit and microleakage under a stereomicroscope using the microscope imaging software and its measurement tool. STATISTICAL ANALYSIS USED: Data collected were subjected to statistical analysis using SPSS 27.0. Intragroup and intergroup comparison was done using the Mann-Whitney U test. The Chi-square test was applied to check the depth of penetration of dye based on percentages. RESULTS: The marginal gap of zirconia occlusal veneers fabricated with CAD-CAM is higher compared to that of prefabricated occlusal veneers. Similarly, the depth of penetration of dye is higher in CAD-CAM-milled zirconia occlusal veneers than prefabricated occlusal veneers. CONCLUSION: The marginal fit of prefabricated occlusal veneer is better than the marginal fit of zirconia occlusal veneers fabricated with CAD-CAM. Similarly, it can also be concluded that the microleakage of prefabricated occlusal veneer is less compared to the CAD-CAM-milled zirconia occlusal veneers.

5-Year clinical performance of ceramic onlay and overlay restorations luted with light-cured composite resin.

OBJECTIVES: This prospective clinical trial evaluated the clinical performance of ceramic partial coverage indirect adhesive restorations (PCIARs) in posterior teeth luted with a light-cured composite resin. METHODS: From April 2016 to January 2017, a total of 60 patients (27 males, 33 females; mean age: 42.2 ± 10.86 years old) received 83 glass-ceramic PCIARs (26 onlay, 57 overlay) made of IPS Emax CAD (Ivoclar Vivadent). All restorations were luted with a light-cured composite resin (Filtek Z250, 3 M ESPE) by two operators. Two independent calibrated examiners blinded to the operators performing the treatment evaluated the restorations at baseline, 1-year, and 5-year following FDI World Dental Federation criteria including esthetic, functional, and biological properties. Data were analyzed with the Friedman test and the Wilcoxon sign test (p < 0.05). RESULTS: None of the restorations failed due to fracture or retention loss. One restoration was clinically unsatisfactory because of secondary caries. Marginal staining (p:0.000), marginal adaptation (p:0.018) showed significant differences between 1-year and 5-year recall. CONCLUSIONS: The PCIARs demonstrated excellent clinical performance at 1-year period. The degradation parameters appeared as minor staining and minor irregularities after 5-year, without any affect on the clinical performance. CLINICAL SIGNIFICANCE: Our findings provide evidence that the clinical performance of PCIARs luted with a light-cured composite resin was clinically acceptable after a five-year evaluation period. Due to secondary caries, only one restoration was considered clinically unsatisfactory. CLINICALTRIALS REGISTRATION NUMBER: NCT04838483.

Influence of fabrication method on the marginal fit of temporary restorations.

Computer-aided manufacturing (CAM) technology allows the use of different manufacturing techniques. This in vitro study aimed to evaluate the marginal fit of temporary restorations manufactured using conventional chairside methods, milling, and three-dimensional printing. Fifteen 3-element temporary restorations specimens were produced and categorized into three groups: non-digital, obtained using the conventional chairside method (GC); milled (GM); and three-dimensionally printed (GP). Marginal fit was assessed using scanning electron microscopy (SEM) performed under two conditions: one with only the central screw tightened, and the other with all three screws tightened. Horizontal misfit values were categorized as over-, equal-, and under-extended and qualitatively analyzed. Statistical analysis was performed using the Tukey-Kramer test (α=0.05). In the vertical assessment, three-dimensionally printed restorations demonstrated greater misfit than restorations obtained by milling and the conventional chairside method (P<0.05). In the horizontal assessment, the misfit in the GP group was significantly higher than that in the GM and GC groups. Restorations obtained using the conventional chairside method and milled provisional restorations showed more favorable results than three-dimensionally printed restorations.

The effect of different deep margin elevation methods on the fracture strength of CAD-CAM restorations.

PURPOSE: To evaluate the effect of two resin composites (with different viscosities) and the elevation amount on fracture strength and fracture behavior of molars with and without deep margin elevations (DME). METHODS: 70 extracted, caries-free human molars were selected. All teeth were prepared as MOD onlay cavities with a margin 2 mm below the cemento-enamel junction (CEJ) on the mesial and buccal sides and 2 mm above the CEJ on the distal side. The teeth were divided into two groups according to the type of resin composite used in margin elevation, elevated with flowable composite (Universal Flo) or condensable composite (G-Aenial Posterior). These two groups were further subdivided into subgroups in which the elevation was 2, 3, or 4 mm, and a control group in which the non-elevated indirect restoration was directly bonded to the subgingival margin, making a total of seven groups (n= 10). After elevations, the restorations were completed using a nanoceramic CAD-CAM block (Cerasmart A3 HT) and as adhesive cement, G-Cem Link Force. Static force was applied to the restored teeth using a universal testing machine at an angle of 15° until fracture occurred. Fracture strength values were recorded, and fracture types were examined under 6x magnification. One-way ANOVA was carried out to determine the effect of DME on the fracture strength. A two-way ANOVA was conducted to investigate main and interaction effects of the material type used in the elevation and the amount of elevation made on the fracture strength (P< 0.05). RESULTS: Using flowable or condensable composite as elevation material did not affect the fracture strength of CAD-CAM restorations. Flowable and condensable composites of 2, 3, or 4 mm did not significantly affect fracture strength values for either material. Specimen margins with and without elevation exhibited similar fracture strength values. The type of material used in the elevation and the amount did not affect the fracture strength of teeth. CLINICAL SIGNIFICANCE: The deep margin elevation technique for teeth with carious lesions extending subgingivally, may be useful in routine practice.

Accuracy and adaptation of one-piece endodontic crowns fabricated through 3D printing and milling.

STATEMENT OF PROBLEM: High-level evidence regarding the accuracy and adaptation of 1-piece endodontic crowns fabricated by using 3-dimensional (3D) printing technology is lacking. PURPOSE: The purpose of this in vitro study was to compare the accuracy and adaptation of 1-piece endodontic crowns produced through 3D printing and computer-numerical-control milling technology and to explore the influence of trueness on 1-piece endodontic crown adaptation. MATERIAL AND METHODS: One-piece endodontic crowns were prepared for a typodont right mandibular first molar, scanned with a 3Shape E3 scanner, and designed with a computer-aided design software program. Two types of 1-piece endodontic crowns were fabricated: 3D printed by using resin and zirconia slurry and milled from Grandio and zirconia blocks. A reverse engineering software program was used to superimpose 4 groups of crowns with the reference crowns used for accuracy analysis. Microcomputed tomography was used to measure 1-piece endodontic crown adaptation. The correlation between trueness and adaptation was evaluated through the Spearman correlation test (α=.05). RESULTS: Milled resin-based 1-piece endodontic crowns demonstrated better trueness on marginal and occlusal surfaces compared with 3D printed ones (P<.001). However, no significant difference was observed in the trueness of intaglio surfaces between the 2 groups (P>.05). The milled group exhibited better adaptations than the printed one (P<.05). For zirconia 1-piece endodontic crowns, no significant differences were found in trueness or adaptation between the milled and printed groups (P>.05). Notably, the trueness of the axial wall had the greatest impact on overall crown adaptation, with its adaptation closely linked to the trueness of each area, particularly the axial wall. CONCLUSIONS: Milled resin-based 1-piece endodontic crowns exhibited higher levels of trueness and adaptation compared with 3D printed ones, while 3D printed zirconia 1-piece endodontic crowns were comparable with milled ones.

Flowable bulk-fill versus layering restorative material on Class II restorations: A randomized clinical trial.

OBJECTIVE: This study evaluated the clinical performance of Class II restorations made with flowable bulk-fill base versus conventional layering ORMOCER-based restorative material in a split-mouth randomized clinical trial. METHODS: Thirty patients received two class II restorations (n = 60) performed with different strategies. All preparations received the application of the universal self-etching adhesive system according to the manufacturer's recommendation, followed by the placement of a sectional matrix, wooden wedge, and separation ring. The first restoration was performed using 4 mm of flowable bulk-fill material covered by 2 mm of conventional viscosity restorative material (Bulk-fill technique). The second restoration was performed only with the conventional viscosity material, with a maximum of 2 mm thick increments, up to fill the cavity (Layering technique). After occlusal adjustment, the same polishing system was used for all restorations. Evaluations using the FDI criteria were conducted after 7 days, 12, and 24 months. Data were analyzed with the Fisher's Exact test (α=0.05). RESULTS: From 30 participants, 24 attended the 24-month recall, and 48 restorations were evaluated. All restorations received acceptable overall scores for esthetic and biological properties after this period, while only 6.66 % of the restorations exhibited unacceptable overall scores for the functional properties in both groups. No significant differences between the tested restorative materials and techniques were found for each FDI criterion assessed. The success rate after 2 years was 93.33 % for both groups. CONCLUSION: Both restorative materials exhibited good clinical performance for the parameters analyzed with no differences between them after 24-month follow-up. CLINICAL RELEVANCE: Flowable bulk-fill ORMOCER-based material is a suitable alternative for direct Class II restorations, providing good clinical outcomes and simplifying the restorative procedure. CLINICAL TRIAL REGISTRATION NUMBER: RBR-6mvp9w.

Performance of low shrinkage Bis-EFMA based bulk-fill dental resin composites.

OBJECTIVES: The purpose of this study was evaluating the performance of new Bis-EFMA based bulk-fill composites with common methacrylate based composites and commercial dental composites. METHODS: The Bis-EFMA monomer was synthesized and the novel Bis-EFMA based bulk-fill composites were prepared. The resin composite samples were co-cultured with human gingival epithelial cells and human dental pulp stem cells to test the biocompatibility. The edge adaptation was observed under a combination of stereoscope and scanning electron microscope. The internal hardness was measured using a Vickers microhardness tester after one-time filling of cavities prepared in extracted teeth. After friction and wear test on the surface of the resin composites, the surface morphology and volume wear of each group were measured by the optical profilometer. The color stability was measured by a colorimeter. RESULTS: Direct contact with human gingival epithelial cells and human dental pulp stem cells did not cause significant changes in their growth density and morphology, indicating good biocompatibility of Bis-EFMA group (p > 0.05). The continuous margin proportion of the Bis-EFMA group was as good as commercial bulk-fill composites (p > 0.05). The sectional microhardness results showed that the Bis-EFMA group had the highest microhardness. After the friction and wear test, the volume wear of the Bis-EFMA group was minimal, indicating its good wear resistance and mechanical strength. Color changes in all resin groups after 28 days of immersion were within the clinically acceptable range. SIGNIFICANCE: The addition of Bis-EFMA demonstrated excellent biocompatibility, edge adaptation and color stability comparable to commonly used clinical bulk-fill composites, along with preferable mechanical strength, friction and wear resistance. Bis-EFMA based bulk-fill composites have the potential to be employed as a bulk filling material in commercial dental composite applications.