Tensile Strength and Durability of Bovine Dentin

Abstract

This study investigated the effects of thermal cycling on the tensile strength of dentin. Bovine dentin were divided into 10 groups, which were then subjected to various conditions: intact after preparation, thereby serving as a control; heating in boiling water for 45 minutes; 10,000 thermal cycles in water; 10,000 thermal cycles in PBS; storage in water at 5, 23, or 55℃ for two weeks; and storage in PBS at 5, 23, or 55℃ for two weeks. Subsequently, bovine dentin were trimmed into dumbbell-shaped specimens and the tensile test performed in distilled water at 37℃. Mean tensile strengths were compared statistically by one-way ANOVA and Fisher's PLTD test (p<0.05). Fracture surfaces were observed by scanning electron microscopy, and reliability of the results was analyzed with Weibull distribution. Tensile strength did not significantly change after thermal cycling or storage in water and PBS at all temperatures tested (71.2-77.0 MPa) but decreased after treatment with boiling water (65.5 MPa).

Relation between incremental lines and tensile strength of coronal dentin

“…Using the low-speed diamond saw, 1-mm-thick dentin slabs were prepared from the labial surfaces of bovine incisors. As per the preparation procedure in previous reports 19,[23][24][25] for BPa group, each dentin slab was cut parallel to the plane which contained the incisal edge and at the nearest point to the root apex on the cervical line. Each dentin slab was cut at 2.4-3.4 mm from the labial surface and it ran parallel to the incremental lines (Fig.…”

“…In our previous study 24) , when the direction of loading was directed parallel to the incremental lines in bovine coronal dentin (i.e., BPa), tensile strength was measured as 78.1±6.1 MPa. In that study 24) , dumbbell-shaped specimens with a narrow central portion (1.0×1.0×1.5 mm) trimmed from rectangular blocks (8.0×3.0×1.0 mm) were used.…”

“…In that study 24) , dumbbell-shaped specimens with a narrow central portion (1.0×1.0×1.5 mm) trimmed from rectangular blocks (8.0×3.0×1.0 mm) were used. In the present study, tensile strength of BPa was measured lower at 62.3±5.7 MPa.…”

“…However, it was not possible to perform tensile testing for BPe, HPa, HPe groups using the specimen size of previous study 24) . If strict adherence to previous specimen size 24) were to be observed in this study, it would mean that investigations for different tensile orientations would be forfeited.…”

“…Specimen size and shape determine tensile test results, and dumbbell-shaped specimens were reportedly useful for identifying defects easily 5,19,[23][24][25][26] . For this reason, a profi ling machine was used to produce uniformly shaped dumbbell specimens in this study, and that the surfaces of the narrow central portion were fi nished with 1200-grit wet silicon carbide papers 5,19,[23][24][25][26] .…”