Biomechanical consideration in tooth-supported glass-ceramic restorations: A systematic review and meta-analysis of survival rates and irreparable failures.

STATEMENT OF PROBLEM: Knowledge on the biomechanical behavior of glass-ceramics, their survival rate over time, and their potential failures is essential for decision-making in clinical practice. Systematic reviews and meta-analysis of their survival rates and irreparable failures are lacking. PURPOSE: The purpose of this systematic review and meta-analysis was to evaluate the survival rates and irreparable failures of various monolithic glass-ceramic dental restorations to help determine biomechanical indications. MATERIAL AND METHODS: A comprehensive literature search was conducted across the PubMed, Scopus, Web of Science, and EMBASE databases based on the population, intervention, comparison, and outcome (PICO) question, risk of bias assessment, data extraction, subgroup analysis, and meta-analysis. Both randomized and nonrandomized clinical trials that reported survival rate and irreparable failure were screened. The risk, with a 95% confidence interval, was calculated by using the Mantel-Haenszel method. RESULTS: A total of 46 articles met the inclusion criteria: 8 for laminate veneers, 20 for partial coverage restorations, 11 for single crowns, and 6 for fixed partial dentures, encompassing 1715 participants rehabilitated with 4209 restorations. The estimated cumulative survival rate for partial coverage restorations was 90% over an average span of 6.2 years, with an irreparable failure occurrence of n=5.9. Laminate veneers had a survival rate of 90.2% over 6.5 years, with an irreparable failure occurrence of n=8.2. Single crowns had a survival rate of 96% over 4.6 years and an irreparable failure of n=2.7. Conversely, fixed partial dentures had a survival rate of 76.1% over 6.5 years with an irreparable failure of n=5.2. CONCLUSIONS: Glass-ceramic materials demonstrate relatively high survival rates, indicating that they provide a safe and reliable option for partial coverage restorations, laminate veneers, and single crowns. However, fixed partial dentures had a higher proportion of irreparable failures and a lower survival rate, and caution is required.

Fatigue survival and damage modes of lithium disilicate and resin nanoceramic crowns.

INTRODUCTION: Polymer-based composite materials have been proposed as an alternative for single unit restorations, due to their resilient and shock absorbing behavior, in contrast to the brittleness of ceramic materials that could result in failure by fracture. OBJECTIVE: To evaluate the fatigue strength and damage modes of monolithic posterior resin nanoceramic and lithium disilicate glass ceramic crowns. METHODOLOGY: Twenty-six resin nanoceramic (RNC) and lithium disilicate glass ceramic (LD) 2 mm monolithic crowns (n=13) were cemented on composite resin replicas of a prepared tooth and subjected to cyclic load with lithium disilicate indenters for 2 million cycles. Specimens and indenters were inspected every 500,000 cycles and suspended when presenting fractures or debonding. Surviving specimens were embedded in epoxy resin, polished and subsurface damage was analyzed. Specimens presenting fractures or severe subsurface damage were considered as failures. Survival data was subjected to Fisher's exact test; damage modes were subjected to Mann-Whitney test (p<0.05). RESULTS: There were no debonding, cohesive or catastrophic failures. Considering subsurface damage, 53.8% of RNC and 46.2% of LD crowns survived the fatigue test, presenting no statistical difference. Chief damage modes were radial cracks for RNC and inner cone cracks for LD, presenting no statistical difference. CONCLUSIONS: The results suggest that if debonding issues can be resolved, resin nanoceramic figures can be an alternative to posterior crowns. Although distinct, damage modes revealed potential to cause bulk fracture in both glass ceramic and resin nanoceramic crowns.

Fatigue survival and damage modes of lithium disilicate and resin nanoceramic crowns

Abstract Polymer-based composite materials have been proposed as an alternative for single unit restorations, due to their resilient and shock absorbing behavior, in contrast to the brittleness of ceramic materials that could result in failure by fracture. Objective: To evaluate the fatigue strength and damage modes of monolithic posterior resin nanoceramic and lithium disilicate glass ceramic crowns. Methodology: Twenty-six resin nanoceramic (RNC) and lithium disilicate glass ceramic (LD) 2 mm monolithic crowns (n=13) were cemented on composite resin replicas of a prepared tooth and subjected to cyclic load with lithium disilicate indenters for 2 million cycles. Specimens and indenters were inspected every 500,000 cycles and suspended when presenting fractures or debonding. Surviving specimens were embedded in epoxy resin, polished and subsurface damage was analyzed. Specimens presenting fractures or severe subsurface damage were considered as failures. Survival data was subjected to Fisher's exact test; damage modes were subjected to Mann-Whitney test (p<0.05). Results: There were no debonding, cohesive or catastrophic failures. Considering subsurface damage, 53.8% of RNC and 46.2% of LD crowns survived the fatigue test, presenting no statistical difference. Chief damage modes were radial cracks for RNC and inner cone cracks for LD, presenting no statistical difference. Conclusions: The results suggest that if debonding issues can be resolved, resin nanoceramic figures can be an alternative to posterior crowns. Although distinct, damage modes revealed potential to cause bulk fracture in both glass ceramic and resin nanoceramic crowns.