Influence of central and peripheral dentin on micro-tensile bond strength estimated using a competing risk model. (March 2021)

• Record Type: Journal Article
• Authors: Tichy, Antonin; Brabec, Marek; Bradna, Pavel; Hosaka, Keiichi; Chiba, Ayaka; Tagami, Junji
• Is Part Of: Journal of the mechanical behavior of biomedical materials. Volume 115(2021)
• Publication Date: 2021-03
• Subjects: Adhesion -- Dentin -- Failure mode -- Weibull analysis -- Competing risks; Biomedical materials -- Periodicals; Biomedical materials -- Mechanical properties -- Periodicals; Biomedical materials; Biomedical materials -- Mechanical properties; Periodicals; Electronic journals; 610.28
• DOI: 10.1016/j.jmbbm.2020.104295
• Languages: English
• ISSNs: 1751-6161

Abstract

Abstract: The bonding performance of dental adhesives is most frequently evaluated using the micro-tensile bond strength (μTBS) test. Despite lacking evidence, peripheral specimens are often discarded to avoid regional variability. This study, therefore, examined whether μTBS to central and peripheral dentin differed. Dentin surfaces of extracted human molars were bonded with various self-etch adhesives, built up with a resin composite, cut into beams, and stressed in tension. Failure mode was classified as adhesive, cohesive in dentin, or other using scanning electron microscopy. Since cohesive failures in dentin were frequent and could confound μTBS results, the data from central/peripheral dentin were analyzed using a Weibull competing risk (CR) model distinguishing failure modes, and its outcomes were compared to a conventional failure mode non-distinguishing Weibull model. Based on the strength data of cohesively failed specimens, the CR model also estimated the strength of dentin. For comparison, the ultimate tensile strength (UTS) of dentin was measured in both regions. The conventional model suggested that peripheral μTBS was higher than central μTBS. Conversely, the CR model disclosed no significant difference in μTBS between the regions but indicated a higher strength of peripheral dentin. This finding was confirmed by UTS measurements, and further supported by the significantly higher incidence of cohesive failures in central dentin. Therefore, peripheral specimens can be used in the μTBS test as well as central ones, but a CR model should be used for statistical analysis if cohesive failures in dentin are frequent, as the strength of peripheral dentin is higher. Graphical abstract: Image 1 Highlights: Strength data were analyzed using a failure mode distinguishing competing risk model. Micro-tensile bond strength to central and peripheral dentin was similar. Fewer adhesive failures and more cohesive failures occurred in central dentin. Central dentin exhibited significantly lower strength than peripheral dentin. The use of a competing risk model permits the testing of specimens from both regions.