Long-term performance of ceramic in/-onlays vs. cast gold partial crowns - a retrospective clinical study.

OBJECTIVES: To assess the long-term clinical performance of ceramic in-/onlays (CIOs) and cast gold partial crowns (CGPCs) in posterior teeth in terms of success, survival, complications (biological, technical) and quality. MATERIAL AND METHODS: In a retrospective study, a total of 325 patients were recorded after up to 24.8 years (mean 13.9 ± 3.8 years) having (pre-)molars restored with CIO (Empress I, Ivoclar Vivadent, n = 161) and CGPC (Degunorm, DeguDent, n = 164) by supervised undergraduate students. A total of 296 restorations were assessed clinically and radiologically in healthy and endodontically treated teeth using modified United States Public Health Service (USPHS) criteria. Cumulative success and survival rates of the restorations were calculated using Kaplan-Meier estimates. Biological and technical complications were recorded. Status of oral health comprising caries risk and localized periodontitis were assessed. RESULTS: The cumulative success rates of CIOs were 92.1% and of CGPCs 84.2% after mean service times of 14.5 years. The annual failure rates of total service times were 0.5% in teeth restored with CIO (n = 155) and 0.7% in teeth restored with CGPC (n = 163). The cumulative survival rates of CIOs were 93.9% after a mean service time of 15.2 years and decreased to 91.7% after 23.5 years. The cumulative survival rates of CGPCs were 92.6% after a mean service time of 14.9 years and 91.8% after 23.5 years. Complications in CIOs (n = 149) were ceramic fracture (6.7%), secondary caries (4.7%), endodontic complication (2.7%) and tooth fracture (1.3%) compared to CGPCs (n = 147) with endodontic complication (8.8%), secondary caries (4.8%) and decementation (2.0%). Endodontically treated teeth restored with CIO or CGPC revealed significantly less often success compared with corresponding vital teeth (p = .02). CIOs and CGPCs revealed clinically and radiographically good and excellent qualities with 71.8% (107/149) and 68% (100/147) without any significant differences regarding type of restoration. CONCLUSIONS: Both CIOs and CGPCs achieved high survival rates up to 24.8 years when performed by supervised undergraduate students. The longevity of the restorations may benefit from the intraoral repair of accessible defects and, in case of pulp infection or necrosis, an adequate endodontic management. CLINICAL RELEVANCE: CIOs and CGPCs made by supervised undergraduate students are proper restoration types in posterior teeth in the long-term. An adequate preparation design, meticulous care in the inserting technique and constant biofilm removal due to proper oral hygiene combined with professional maintenance care are substantial. The clinical long-term performance was mostly limited by ceramic fractures in CIOs and endodontic complications in CGPCs.

Fracture behavior of short fiber-reinforced CAD/CAM inlay restorations after cyclic fatigue aging.

The aim of this study was to assess the fracture behavior of molar teeth restored with MOD inlays made of experimental short fiber-reinforced CAD/CAM composite block (SFRC CAD) before and after cyclic fatigue aging. Standardized MOD cavities were prepared on 60 intact mandibular molars. Three groups of CAD/CAM made inlay restorations (Cerasmart 270, Enamic, and SFRC CAD) were fabricated (n = 20/group). All restorations were luted with self-adhesive dual-cure resin cement (G-Cem One). Half of restored teeth per each group (n = 10) were quasi-statically loaded until fracture without aging. The other half underwent cyclic fatigue aging for 500,000 cycles (Fmax = 150 N) before being loaded quasi-statically until fracture. Then, the fracture type was visually inspected. The microstructure and elemental content of CAD/CAM materials were assessed using SEM and EDS. Two-way analysis of variance (ANOVA) was used to statistically examine the data, and it was followed by the Tukey HSD test (α = 0.05). ANOVA demonstrated that both material type and aging had a significant effect (p < 0.05) on the load-bearing capacity values of the restorations. Teeth restored with SFRC CAD showed significantly the highest (p < 0.05) load-bearing capacity (2535 ± 830 N) after fatigue aging among all groups. SEM images showed the ability of short fibers in SFRC CAD composite to redirect and hinder crack propagation. With regard to fracture mode, Enamic group revealed 85% of catastrophic failure (vs. 45% and 10% for Cerasmart 270 and SFRC CAD, respectively). Large MOD cavities on molar teeth were most favorably restored with SFRC CAD inlays, yielding the highest load-bearing capacity and more restorable failures.

Clinical performance comparison between lithium disilicate and hybrid resin nano-ceramic CAD/CAM onlay restorations: a two-year randomized clinical split-mouth study.

A total of 20 lithium disilicate glass-ceramics (IPS e.max CAD, Ivoclar Vivadent) and 20 resin nano-ceramic (Voco Grandio Blocks) onlay restorations were performed in 20 patients using a split-mouth design to compare the two-year clinical performance of lithium disilicate and resin nano-ceramic onlay restorations. Both restorations were evaluated at baseline, one-year, and two-year clinical follow-ups based on the modified United States Public Health Service (USPHS) criteria. Chi-square and Fisher's exact tests showed no statistically significant difference between Voco Grandio and IPS e.max ceramic restorations for all evaluated parameters during the different follow-up periods (p > 0.05). Cochrane's and MC-Nemar's tests indicated statistically significant differences regarding color match within the Voco Grandio group. They also indicated statistically significant differences in marginal discoloration, marginal adaptation, surface texture, and postoperative hypersensitivity within both ceramic material groups (p < 0.05). Kaplan-Meier curve indicated that the survival rate of both ceramic materials was 90%. After two years of clinical service, IPS e.max CAD and Voco Grandio onlay restorations exhibited similar clinical performance.

Do onlays and crowns offer similar outcomes to posterior teeth with mesial-occlusal-distal preparations? A systematic review.

OBJECTIVE: Teeth prepared for mesial-occlusal-distal (MOD) restorations have a significant risk of cusp fracture. Crowns and onlays can provide cusp coverage to reinforce posterior teeth at risk. Onlays are often more conservative of tooth structure which may be an advantage for teeth with large MOD preparations. It remains uncertain how onlays and crowns compare for posterior teeth with MOD tooth structure loss. The purpose of this systematic review was to compare the resistance to fracture, success rate, survival rate, and failure rate of teeth with MOD preparations restored with onlays or crowns. MATERIALS AND METHODS: An electronic search queried Medline (PubMed), Embase (Ovid), Scopus, the Cochrane Library, and grey literature (OpenGrey) from database inception through April 29, 2023. RESULTS: After eliminating duplicates and irrelevant records, 32 manuscripts were assessed. Only three publications met the criteria for inclusion. Most exclusions were due to poor reporting of restorative design and the amount of tooth structure remaining, or due to combining various restorative designs. Due to the limited sample size and high heterogeneity, no meta-analysis was conducted. One study observed a better outcome for onlays and two observed no difference. All three studies reported the mode of failure for crowns as more catastrophic whereas teeth with onlays could be salvaged. CONCLUSIONS: Onlays may be an advantageous alternative to crowns for teeth with MOD preparations, but the level of evidence is insufficient to draw meaningful conclusions. CLINICAL SIGNIFICANCE: Current evidence is insufficient to determine whether onlays or crowns are providing a different outcome when used to restore posterior teeth with MOD tooth structure loss. However, the fracture of teeth with MOD tooth structure loss restored with onlays appears to be less catastrophic than when restored with crowns.

Influence of retainer design and number of inlay boxes on the biomechanical behavior of zirconia cantilever resin bonded fixed dental prosthesis.

OBJECTIVES: The development of dental adhesives with enhanced bond strength has assisted minimally invasive dentistry. The aim of this study was to evaluate the fracture load and stress distribution pattern of two retainer designs for posterior cantilever resin bonded fixed dental protheses (RBFDPs). MATERIALS AND METHODS: Forty human mandibular molars were divided into two groups according to the retainer design; lingual coverage (LC) and occlusal coverage (OC) retainers. Each main group was then divided according to the number of inlay boxes (n = 10); one inlay and two inlay boxes. High translucency (3Y) zirconia was used to manufacture all restorations, and a dual-polymerizing adhesive resin cement was used for bonding. All specimens underwent 10,000 cycles of thermocycling (5-55°C), 240,000 cycles of dynamic loading (50 N, descending speed v = 30 mm/second, frequency = 1.6 Hz), and failure load test. Both one-way and two-way ANOVA tests were used to analyze the data. The four models included in the in-vitro study are part of the finite element analysis (FEA). When the restorations failed, maximal principal stress values on restorations, enamel, dentin, and luting resin were investigated. RESULTS: A statistically significant (p = 0.018) higher failure load was recorded for OC1 (627.00 ± 153.4 N) than the other groups; (548.0 ± 75.6 N, 521.20 ± 11.3 N, and 509.20 ± 14.9 N for LC1, LC2, and OC2, respectively). With regard to failure mode, one inlay box designs showed more favorable failure pattern than those of two inlay boxes. FEA showed higher stress magnitude transmitted to the tooth structure in models LC2 and OC2. CONCLUSIONS: Lingual coverage and occlusal coverage retainers are promising designs capable to withstand the normal occlusal force for cantilever RBFDP in premolar area. The use of two inlay boxes decreased the fracture load of the two retainer designs and increased the stress transmitted to the tooth and resulted in high incidence of catastrophic failure. CLINICAL SIGNIFICANCE: Monolithic high translucent zirconia RBFDP could be considered as a viable treatment option to substitute missing posterior tooth, with improved esthetics and biocompatibility.

Effect of different intraoral scanning strategies on the marginal and internal fit of CAD-CAM inlay restorations: An in vitro study.

STATEMENT OF PROBLEM: Whether the scanning strategy of intraoral scanners (IOSs) affects the accuracy of the digital recording for an indirect ceramic inlay restoration is unclear. Furthermore, which strategy would be optimal and most effective is uncertain. PURPOSE: The purpose of this in vitro study was to evaluate the impact of 3 different scanning strategies using the Carestream CS 3700 IOS on the marginal and internal fit of a mesio-occluso-distal (MOD) ceramic inlay restoration. MATERIAL AND METHODS: A typodont master model (ANA-4 VCER; Frasaco) was used with a standardized preprepared MOD inlay maxillary first molar typodont tooth (ANA-4 ZP16 CER99-008; Frasaco) (N=30). These inlay preparations were scanned with the CS 3700 IOS using 3 different scanning strategies: linear, wave, and S-figure scanning strategies. Each scan strategy group was scanned 10 times for all groups to obtain 30 standard tessellation language (STL) files. Thirty restorations were milled from lithium disilicate CAD blocks (IPS e.max; Ivoclar AG) and cemented into their typodont-prepared inlay cavities. A single examiner used a stereomicroscope to measure the marginal and internal gaps at the predetermined points. A 1-way ANOVA was used for the statistical analysis, followed by the Tukey post hoc test with Bonferroni adjustment. All tests were 2-tailed (α=.05). RESULTS: All scanning strategy groups demonstrated statistically significant differences for the marginal and internal fit of the inlay restorations (P<.001). Overall, the linear scanning strategy showed the lowest mean marginal and internal gap values (29.2 ±3.6 µm and 39.0 ±6.4 µm), followed by the wave scanning strategy, which had comparable mean marginal and internal gap values: 49.1 ±3.6 µm and 48.2 ±6.0 µm, respectively. The S-figure scan strategy had the highest mean marginal and internal gap values: 50.2 ±12.6 µm and 71.3 ±7.7 µm, respectively. CONCLUSIONS: Inlay restorations scanned by the linear scan strategy had the best marginal and internal fit when scanned with the CS 3700 IOS.

Effect of preparation design on fracture strength of compromised molars restored with direct composite resin restorations: An in vitro and finite element analysis study.

STATEMENT OF PROBLEM: More data are needed on the influence of preparation design on the fracture strength, failure type, repairability, and polymerization-induced cracks of molar teeth restored with direct composite resin restorations. PURPOSE: This in vitro and finite element analysis study investigated the effect of different preparation designs on fracture strength, failure type, repairability, tooth deformation, and the formation of polymerization-induced cracks of compromised molars restored with direct composite resin restorations. MATERIAL AND METHODS: Human molars (n=64) were randomly assigned to 4 different preparation designs: undermined inlay (UI), extended inlay (EI), restricted overlay (RO), and extended overlay (EO). The teeth were restored using direct composite resin and subjected to artificial thermomechanical aging in a mastication simulator, followed by load-to-failure testing. Three-dimensional (3D) finite element analysis was conducted to assess tooth deformation. Polymerization-induced cracks were evaluated using optical microscopy and transillumination. The fracture strength data were analyzed using a Kruskal-Wallis test, while the failure mode, repairability, and polymerization cracks were analyzed using the Fisher exact test (α=.05). RESULTS: All specimens withstood thermomechanical aging, and no statistically significant difference in fracture strength was observed among the 4 preparation designs (P>.05). The finite element analysis showed differences in tooth deformation, but no correlation was observed with in vitro fracture resistance. The RO and EO groups presented significantly more destructive failures compared with the UI and EI groups (P<.01). The RO group had significantly fewer repairable failures than the UI and EI groups (P=.024). A correlation was found between higher frequencies of repairability and higher tooth deformation. A significant correlation between the increase in microfractures and preparation design was observed (P<.01), with the UI group exhibiting a higher increase in microfracture size compared with the EO group (P<.05). CONCLUSIONS: No influence of preparation design on the fracture strength of compromised molars restored with direct composite resin restorations was evident in this study, but the failure mode of cusp coverage restorations was more destructive and often less repairable. The finite element analysis showed more tooth deformation in inlay preparations, with lower stresses within the root, leading to more reparable fractures. Since cusp coverage direct composite resin restorations fractured in a more destructive manner, this study suggests that even a tooth with undermined cusps should be restored without cusp coverage.

Two­year clinical performance of indirect restorations fabricated from CAD/CAM nano hybrid composite versus lithium disilicate in mutilated vital teeth. A randomized controlled trial.

TRIAL DESIGN: This is a randomized, controlled, superiority, double-blinded, parallel-group, two-arms trial with an allocation ratio of 1:1. The aim of this trial was to compare the two-year clinical performance of partial indirect restorations fabricated from CAD/CAM nano-hybrid composite and ceramic lithium disilicate blocks using the modified USPHS criteria. METHODS: In two parallel groups (n = 50 restorations), fifty participants having mutilated vital teeth with a minimum of two remaining walls were randomly enrolled in this trial and received indirect restorations of either nano-hybrid composite resin blocks (Brilliant, Coltene, Switzerland) or Lithium Disilicate (IPS Emax CAD). The restorations were assessed using modified USPHS criteria by two independent blinded assessors at baseline, six months, one-year and two years follow-up visits. Categorical and ordinal data were presented as frequencies and percentages. Categorical data were analyzed using the chi-square test. Ordinal data were analyzed using the Mann-Whitney U test for intergroup comparisons and Freidman's test followed by the Nemenyi post hoc test for intragroup comparisons. Numerical data were presented as mean and standard deviation values. They were analyzed for normality using the Shapiro-Wilk test. Data were found to be normally distributed and were analyzed using the independent t-test. The significance level was set at p ≤ 0.05 within all tests. RESULTS: Forty-eight participants received the allocated intervention and completed the follow-up periods. There was a statistically significant difference between both tested materials for all USPHS criteria regarding Marginal integrity and Marginal discoloration at six-months Follow-up, but with no statistically significant difference at one- and two-year follow-up. CONCLUSIONS: Both materials showed an acceptable, successful clinical performance along the two-years follow-up period. CLINICAL RELEVANCE: The CAD/CAM nano-hybrid composite blocks are as reliable as Lithium disilicate for restoring mutilated vital teeth.

3D-printed coloured tooth model for inlay preparation in pre-clinical dental education.

INTRODUCTION: Accurate inlay preparation is extremely important in pre-clinical training. However, there is a lack of tools to guide students to efficiently practise inlay preparation. Therefore, a 3D-printed coloured tooth model for inlay preparation was designed to guide beginners to practise inlay preparation by themselves according to different colour prompts. This study aimed to evaluate the benefits of using a 3D-printed coloured tooth model in the pre-clinical training on inlay preparation. MATERIALS AND METHODS: Twenty-eight students in their fourth-year undergraduate dental program participated in this study. The participants were randomly assigned to two groups for the inlay preparation. Group 1 prepared a plain tooth model for the first and fourth attempts and a 3D-printed coloured tooth model for the second and third attempts (n = 14). Group 2 prepared four plain tooth models (n = 14). The first and fourth tooth models prepared by both groups were scored using an evaluation system (Fair Grade 2000, NISSIN). Next, questionnaires answered by students were used to evaluate the benefits of using a 3D-printed coloured tooth model and self-evaluate hands-on ability using a grading system (1 = strongly agree, 2 = agree, 3 = neutral, 4 = disagree, and 5 = strongly disagree). The scores were evaluated statistically using the Mann-Whitney U test, and the given grades are displayed as percentages and mean values. RESULTS: There was an overall increase in the clinical confidence of all students after repeated attempts to prepare an inlay; however, students from group 1, who had used the 3D-printed coloured tooth model, had more positive experiences and comments. The 3D-printed coloured tooth model for inlay preparation has been widely praised by participants. Comparing the average score of the first and fourth preparations, the average score of group 1 increased by 12% (Ø 54.46 ± 8.33, Ø 61.11 ± 7.13, p = .090), while that of group 2 increased by 0.72% (Ø 56.39 ± 9.59, Ø 56.80 ± 8.46, p = .925). CONCLUSION: Students favoured the use of the 3D-printed coloured tooth model, and this improved the average score for inlay preparation. The 3D-printed coloured tooth model for inlay preparation is expected to play an important role in dental education in the future.

Clinical and Radiographic Outcomes of Autogenous Inlay Graft vs Autogenous Onlay Graft for Anterior Maxillary Horizontal Ridge Augmentation: A Randomized Control Clinical Study.

AIM: This study aimed to compare the efficacy of autogenous onlay and inlay grafts for anterior maxillary horizontal ridge augmentation. MATERIALS AND METHODS: This randomized clinical trial was performed on 14 patients with a deficient partially edentulous anterior maxillary ridge (3-5 mm in width). Patients were randomized and grouped into two equal groups: Group A was treated with symphyseal autogenous bone block, which was placed and fixed buccally as an onlay graft, and group B: was treated with symphyseal autogenous bone block, which was interpositioned and fixed in space created between buccal and lingual cortex as inlay graft. Patients were evaluated clinically and radiographically to evaluate the increase of bone width at [Baseline, immediate postoperative (T0)] and six months post-graft (T6). RESULTS: A total of 14 patients (8 males and 6 females) with age range from 20 to 43 years old with a mean of 42.1 years were involved in our study. Radiographically, there was a significant statistical difference in comparing between two groups for the creation of a horizontal alveolar bone at T0. In the inlay group, the mean preoperative bone width was 3.9 ± 0.3 mm at T0 and 5.7 ± 0.5 mm at T6. While in the onlay group, the mean preoperative bone width was 3.7 ± 0.7 mm at T0 while at T6 the mean bone width was 6.1 ± 0.8 mm. This was statistically significant. CONCLUSION: Inlay block graft appears to be a successful treatment option for horizontal ridge augmentation in the maxillary arch. CLINICAL SIGNIFICANCE: both techniques are viable techniques for augmentation of atrophic alveolar ridge with uneventful healing. How to cite this article: Elsayed AO, Abdel-Rahman FH, Ahmed WMAS, et al. Clinical and Radiographic Outcomes of Autogenous Inlay Graft vs Autogenous Onlay Graft for Anterior Maxillary Horizontal Ridge Augmentation: A Randomized Control Clinical Study. J Contemp Dent Pract 2024;25(2):107-113.

Survival and Success Rates of Endodontically Treated Teeth Restored with Full Veneer Crowns or Full Cuspal Coverage onlays: A Systematic Review.

INTRODUCTION: The aim of this paper is to compare the survival and success rates of endodontically treated posterior teeth restored with full veneer crowns or full cuspal coverage onlays in vivo. METHODS: A literature search using PubMed, Medline and Embase via Ovid, and The Cochrane Library retrieved English and non-English language articles from 1946 to April 2022. Electronic searches were supplemented with the use of forward citation chaining via Google Scholar. RESULTS: A total of eleven studies met all predetermined search criteria. Data were extracted and tabulated. Survival rates for onlays ranged from 95% to 100% at two years and 90.7% to 100% at three years with success rates ranging from 86.6% - 96.6% at two years and 86.6% to 96% at three years. Survival results for full veneer crowns were reported at 87.8% at over two years, 95.1% at three years, and 84% - 97.73% at five to ten years. Success rates have been reported at 91.11% - 92.64% at five years and 60% at six years. CONCLUSIONS: The data suggest that the use of onlays instead of full veneer crowns in the restoration of endodontically treated posterior teeth is favourable in the short to midterm.

Co-Influence of Restoration Bonding and Inlay Cavity Design on Fracture Load of Restored Tooth.

INTRODUCTION: The aim of this study was to investigate the co-influence of indirect mesio- occlusal-distal (MOD) cavity geometry and inlay restoration bonding on quasi-static fracture load of the restored tooth. METHODS: Forty-eight intact human molar teeth were selected and prepared for standardized edge-shaped or round-shaped MOD cavities. The resin composite (Cerasmart, GC) inlays were bonded with the state-of-the-art inlay bonding protocol or with intentionally deteriorated bonding using n-hexane-wax solution for preconditioning. Restored teeth were loaded along the long axis of the tooth. Ultimate fracture load was recorded, and the type of fracture was visually determined and classified. Statistical analysis of load values was performed by Kruskal-Wallis test. RESULTS: Round-shaped cavity design with bonded restoration presented the highest fracture load (1658N). Bonding had significant influence on the fracture load of roundshaped cavity design (p=0.0003), whereas cavity design had no influence when the bonding was deteriorated (p=0.8075). In the case of deteriorated bonding, either the inlay or tooth fractured separately whereas in the bonded inlays fractures were commonly found both in the tooth and inlay. CONCLUSIONS: According to this study, bonded inlay restoration increased fracture resistance, while cavity design had no statistical difference on fracture resistance of the restored tooth.

Digitally manufactured partial coverage restorations: is it time to down the impression trays or still a work in progress?

DATA SOURCES: Pubmed, EMBASE, Scopus, Web of Science and Cochrane library databases were used as the data sources for this systematic review. Manual search of the reference lists of the included studies was also conducted. STUDY SELECTION: The aim of the systematic review was to compare a fully digital workflow to a fully conventional workflow in the fabrication of partial coverage restorations. Partial coverage restorations were defined as inlays, onlays, overlays and endocrowns. Four independent calibrated reviewers screened studies that fulfilled a predefined PICOS framework. Population was specified as an abutment tooth requiring a partial coverage restoration. The intervention was a fully digital workflow compared to a fully conventional workflow. Outcomes were accuracy, marginal and internal fit, success, survival, complication rates and patient-reported outcomes. Study design included both clinical and in vitro studies. DATA EXTRACTION AND SYNTHESIS: A total of 23 articles were included in qualitative synthesis ranging from 2007 to 2021. Twenty-one of these were in vitro studies. Two authors independently reviewed the included articles, performed data extraction, and evaluated the risk of bias via an adapted Checklist for Reporting In Vitro studies (CRIS) for in vitro studies and Reporting Randomised Clinical studies (RoB2) for clinical studies. RESULTS: Seventeen studies assessed the marginal and internal fit of onlay and inlay restorations, eight of which found that a conventional workflow demonstrated improved fit compared to digital, whilst the remaining nine studies found the contrary. Differing methods were utilised across the studies to assess fit, including: the silicone replica method, microcomputed tomography, microscopy and software-based measurements. Similar fracture strengths were reported between both conventional and digital workflows in three studies. One clinical study assessed survival rates of both pressed and CAD/CAM ceramic restorations and found the survival outcomes to be similar after seven years. No studies were found that investigated patient-reported outcomes or endocrowns. CONCLUSIONS: No consensus was reached as to whether the digital or conventional workflow is better.

Quality of CAD-CAM inlays placed on aged resin-based composite restorations used as deep margin elevation: a laboratory study.

OBJECTIVES: To assess the impact of the age of resin-based composite (RBC) restorations used for deep margin elevation (DME) on the marginal quality and fracture resistance of inlays. MATERIALS AND METHODS: Permanent human molars with direct RBC restorations, involving the mesial, occlusal, and distal surface (MOD), were allocated to four groups (each n = 12). Half of the teeth underwent thermomechanical loading including 240,000 occlusal load cycles and 534 thermal cycles (TML, 5 °C/55 °C; 49 N, 1.7 Hz). With RBC left in one proximal box as DME, all teeth received MOD inlays, made from lithium disilicate (LDS) or a polymer-infiltrated ceramic network material (PICN). The restored teeth underwent TML including 1.2 million occlusal cyclic loadings and 2673 thermal cycles. The marginal quality was assessed at baseline and after both runs of TML. Load-to-fracture tests were performed. The statistical analysis comprised multiple linear regressions (α = 0.05). RESULTS: Simulated aging of RBC restorations had no significant effect on the marginal quality at the interface between the RBC and the tooth and the RBC and the inlay (p ≥ 0.247). Across time points, higher percentages of non-continuous margin were observed between the inlay and the tooth than between the tooth and the RBC (p ≤ 0.039). The age of the DME did not significantly affect the fracture resistance (p ≥ 0.052). CONCLUSIONS: Artificial aging of RBC restorations used for DME had no detrimental effect on the marginal quality and fracture resistance of LDS and PICN inlays. CLINICAL RELEVANCE: This laboratory study suggests that-in select cases-intact, direct RBC restorations not placed immediately before the delivery of an indirect restoration may be used for DME.

Vertical ridge augmentation of atrophic posterior mandible with corticocancellous onlay symphysis graft versus sandwich technique: clinical and radiographic analysis.

Alveolar ridge augmentation of atrophic posterior mandibular ridge represents a challenge in oral and maxillofacial surgery to restore aesthetic and function. The aim of the study was to compare the clinical and radiographic outcomes of bone formation in atrophic posterior mandibles augmented using onlay symphysis cortico-cancellous bone block with that augmented using sandwich bone augmentation technique (Inlay). Twelve patients were selected with missing mandibular posterior teeth. CBCT were done for all patients preoperatively to assess the residual bone height, ranged between 5 and 7 mm from the inferior alveolar nerve with adequate sufficient alveolar ridge width more than 4 mm. Patients required bone augmentation procedure with autologous onlay chin graft (group I) versus those used as inlay sandwich technique (group II). Clinical and radiographic analysis were done to analyses the newly formed bone and bone height. Percent of change in bone height was also calculated and revealed that group I was higher than group II, however, statistically insignificant differences between the two groups were found regarding the percentage of newly formed bone. Vertical ridge augmentation procedures using onlay chin graft took lesser time than the interpositional grafting with fixation technique, however, both techniques are promising for vertical ridge augmentation.

Conservatively replacing missing anterior teeth with resin bonded ceramic restorations.

OBJECTIVE: This article describes improvements in materials and adhesion technologies that have facilitated new, minimally invasive treatment for the replacement of missing anterior teeth. CLINICAL CONSIDERATIONS: In the first of two case reports presented, the treatment of a 13-year-old female patient with a missing right lateral mandibular incisor is described. The patient was told she could not have an implant placed until she was 25 years of age and space post orthodontics was inadequate for implant placement. Treatment options included: a provisional removable appliance (flipper), an Essix appliance, or a resin-bonded one-wing lithium disilicate bridge with only slight modification to the right central incisor and a lingual wing on the canine. The second case report describes an adult female patient who had an impacted maxillary left canine that could not be pulled into position and wanted a replacement for the missing No. 11. This article demonstrates how the use a two-abutment bridge consisting of an inlay in the first premolar and a lingual wing with a proximal retention groove and a vertical path of insertion is a viable alternative to an implant or a conventional bridge to replace a maxillary canine with minimal removal of tooth structure. CONCLUSION: With the advent of new ceramic materials and improved adhesion minimally invasive prosthesis can be fabricated to replace missing teeth in the esthetic zone. Usually, one wing with a zirconia framework is recommended but Lithium disilicate can also be used depending on occlusal forces. CLINICAL SIGNIFICANCE: Resin-bonded fixed dental prostheses (RBFDPs) can be used on occasion as a viable alternative to implants but case selection and adherence to appropriate adhesive techniques are key to longevity.

Effect of Ceramic and Dentin Thicknesses and Type of Resin-Based Luting Agents on Intrapulpal Temperature Changes during Luting of Ceramic Inlays.

The adhesive cementation of ceramic inlays may increase pulpal temperature (PT) and induce pulpal damage due to heat generated by the curing unit and the exothermic reaction of the luting agent (LA). The aim was to measure the PT rise during ceramic inlay cementation by testing different combinations of dentin and ceramic thicknesses and LAs. The PT changes were detected using a thermocouple sensor positioned in the pulp chamber of a mandibular molar. Gradual occlusal reduction obtained dentin thicknesses of 2.5, 2.0, 1.5, and 1.0 mm. Light-cured (LC) and dual-cured (DC) adhesive cements and preheated restorative resin-based composite (RBC) were applied to luting of 2.0, 2.5, 3.0, and 3.5 mm lithium disilicate ceramic blocks. Differential scanning calorimetry was used to compare the thermal conductivity of dentin and ceramic slices. Although ceramic reduced heat delivered by the curing unit, the exothermic reaction of the LAs significantly increased it in each investigated combination (5.4-7.9 °C). Temperature changes were predominantly influenced by dentin thickness followed by LA and ceramic thickness. Thermal conductivity of dentin was 24% lower than that of ceramic, and its thermal capacity was 86% higher. Regardless of the ceramic thickness, adhesive inlay cementation can significantly increase the PT, especially when the remaining dentin thickness is <2 mm.

Use of zirconia onlays in a maxillary removable implant-supported denture: A clinical report.

A common complication with the use of acrylic resin denture teeth is wear of the occlusal surfaces. Modifying the occlusal surfaces with gold onlays has been suggested to combat this phenomenon. This clinical report describes the use of zirconia as an alternative material on a patient with increased tendencies for occlusal wear. The advantages of using zirconia include wear resistance, decreased cost, and straightforward fabrication.

Shape optimization of a 2-unit cantilevered posterior resin-bonded fixed dental prosthesis.

STATEMENT OF PROBLEM: The cantilevered resin-bonded fixed dental prosthesis (RBFDP) is a feasible and minimally invasive treatment option to restore a single missing tooth, especially when the missing tooth space is small (<7 mm) and cost-effectiveness is essential. However, its long-term survival needs to be improved by increasing its structural strength and interfacial adhesion. PURPOSE: The purpose of this study was to improve the interfacial bonding and to enhance the structural strength of a 2-unit inlay-retained cantilevered RBFDP with a 2-step numerical shape optimization. MATERIAL AND METHODS: A finite element model of a mandibular first molar with a second premolar pontic was constructed. A load of 200 N simulating the average occlusal force was applied on the mesial fossa of the pontic. In the first step, an in-house user-defined material subroutine was used to generate the cavity preparation. The subroutine iteratively changed the tooth tissues next to the pontic to composite resin according to the local stresses until convergence was achieved. In the second step, the subroutine was used to optimize the placement of fibers in the pontic by placing fibers in high-stress regions. To assess the debonding resistance and load capacity of the optimized and conventional designs, further analyses were conducted to compare their stresses at the tooth-restoration interface and those within the restoration. RESULTS: Shape optimization resulted in a shovel-shaped cavity preparation and a pontic with fibers placed near the occlusal surface of the connector region. With the optimized cavity preparation only, the maximum principal stress within the restoration and the tooth structure was reduced from 639.4 MPa to 525.4 MPa and from 381.7 MPa to 352.8 MPa, respectively. With the embedded fibers, the shovel-shaped cavity preparation reduced the maximum interfacial tensile stress by approximately 70% (conventional: 189.6 MPa versus optimized: 57.0 MPa) and the peak maximum principal stress of the veneering composite resin by 45% (conventional: 638.8 MPa versus optimized: 356.5 MPa). The peak maximum principal stress was also reduced for the remaining tooth structure by approximately 30% (conventional: 372.2 MPa versus optimized: 253.1 MPa). CONCLUSIONS: Shape optimization determined that a shovel-shaped retainer with fibers placed near the occlusal surface of the connector area can collectively reduce the interfacial and structural stresses of the 2-unit cantilevered fiber-reinforced RBFDP. This may offer a more conservative treatment option for replacing a single missing tooth.

Volumetric and dimensional accuracy assessment of CAD-CAM-manufactured dental prostheses from different materials.

STATEMENT OF PROBLEM: In computer-aided design and computer-aided manufacturing (CAD-CAM) dentistry, the CAD of the prosthesis represents the clinical prerequisite design to restore the treated tooth. However, how closely the CAM prosthesis shape matches the CAD, particularly in relation to different materials, is unclear. PURPOSE: The purpose of this in vitro study was to evaluate onlays designed and manufactured with the same CAD-CAM system but manufactured with different materials. MATERIAL AND METHODS: A single standard tessellation language (STL) model was used to produce 6 composite resin onlays, 6 leucite glass-ceramic onlays, and 6 lithium disilicate glass-ceramic onlays. The onlays were digitized by using an X-ray microtomographic protocol with a metrological calibration. The CAD model was then compared with the scans of the different onlays. An analysis by region of interest was then carried out to assess the accuracy and reliability of the dimensional accuracy. RESULTS: The composite resin and the lithium disilicate glass-ceramic had the best dimensional accuracy. The leucite glass-ceramic exhibited a lack of trueness linked to consistent overmilling. The composite resin had less peripheral chipping than the glass-ceramics. CONCLUSIONS: The composite resin and the lithium disilicate glass-ceramic material exhibited satisfactory dimensional accuracy. Milling the glass-ceramic before crystallization considerably improved dimensional accuracy.