Standardizing failure, success, and survival decisions in clinical studies of ceramic and metal–ceramic fixed dental prostheses

Abstract

“Nothing worthwhile is ever without complications.”– Nora Roberts The recent increase in reports from clinical studies of ceramic chipping has raised the question of which criteria should constitute success or failure of total-ceramic prostheses. Terminology such as minor chipping[1], partial chipping, technical complications[2, 3], and biological complications have crept into the dental terminology and they have complicated our classification of success and failure of these crown and bridge restorations. Some journals have permitted the reporting of fractures as “complications” and they are not necessarily classified as failures in the study. One study has attempted to classify chipping fractures according to their severity and subsequent treatment.[4] This is a promising approach to resolve the challenges to the classification of chipping fracture. The term ‘chipping fracture’ is more descriptive than ‘chipping’ since the latter term tends to imply an event of minor consequence. Two types of statistics are reported routinely in these studies, i.e., percent success, which is a measure of restorations that survive without any adverse effects, and percent survival, which is a measure of all restorations that survive even though they may have exhibited chipping fracture or they may have been repaired. Why has this scenario occurred? One possible explanation is that many of these types of fractures are very small and do not affect function or esthetics. Another reason is that corporate sponsors prefer to use the term chipping since it does not connote failure in the sense that the term fracture does. In any event, we need to be more precise in our scientific observations of fracture and classifications of the various types of fracture including details on the location of fracture and the prosthesis design configuration. Because of the lack of standardized methods for describing chipping fractures, materials scientists are unable to properly analyze the effect of material properties and design factors on the time-dependent survival probability of ceramic fixed dental prostheses (FDPs). Based on the review of clinical trials and systematic reviews of these trials, the present study was designed to develop guidelines for classifying the functional performance, success, survival, and susceptibility to chipping fracture, and subsequent treatment of ceramic and metal-ceramic restorations. Objective To develop comprehensive descriptive guidelines and a clinical reporting form to assist dental scientists in their analyses of chipping fracture behavior of metal-ceramic and all-ceramic prostheses with particular emphasis on veneered-zirconia restorations. These guidelines are required to optimize the recording of fracture features that can be used to differentiate ceramic chipping fracture from bulk fracture and to assist dentists in identifying subsequent treatment that may minimize the need to replace affected restorations. A recording form for clinical fracture observations must be sufficiently clear and complete so tha...

Microstructural evolution and physical behavior of a lithium disilicate glass–ceramic

“…Another limitation has to do with the reliability of our laboratory measurements. In this study, we have chosen fracture toughness, flexural strength, and elastic modulus as reliable parameters because they have been commonly known as good clinical predictors from past literature even though there was no proven association, at least in clinical dentistry, between these parameters and their clinical outcomes [62,63].…”

Three- to nine-year survival estimates and fracture mechanisms of zirconia- and alumina-based restorations using standardized criteria to distinguish the severity of ceramic fractures

“…There is growing evidence that the incidence of chipping increases on full-ceramic restorations, which in turn has raised the question as to which criteria should determine the "success" or the "failure" of an all-ceramic restoration [25]. Terminologies such as "minor-major" chipping [46][47][48] and "technical complications" [3,49] have blurred the issue as to how the severity of a fracture should be quantified.…”

“…Noteworthy, in their systematic review, Heintze et al [4] attempted to solve the problem by grading veneer chippings from 1 to 3 according to their severity and treatment options. Problematically, the authors did not list the clinical criteria that corresponded to each degree of severity [25]. Moreover, the authors concluded that a better description of the type of veneer fractures or material failures was needed based on the size and location of the breakage.…”

“…Third is the FDI system [24] with its classification into "clinically sufficient/satisfactory," "unsatisfactory but reparable," and "poor." Still, there are ambiguities in these systems which prevent an unequivocal interpretation of published survival estimates [4,25] and therefore fail in delivering a clear message for the clinical decision-making process [25].…”

Low-Fusing Porcelain Glaze Application on 3Y-TZP Surfaces can Enhance Zirconia-Porcelain Adhesion

“…However, clinical failures of these kinds of restorations range between 13.0% at 3 years and 15.2% at 5 years (1)(2)(3)(4)(5).…”