Evaluation of the coefficient of thermal expansion of human and bovine dentin by thermomechanical analysis.

The mismatch of thermal expansion and contraction between restorative materials and tooth may cause stresses at their interface, which may lead to microleakage. The present work compared the coefficient of thermal expansion (CTE) with the thermomechanical behavior of human and bovine teeth and determined if the CTE is a suitable parameter to describe tooth behavior. Fifteen human third molar and 15 bovine incisor tooth slices (6×5×2 mm) were allocated to 3 groups according to the test environment: G1 - room condition, G2 - 100% humidity, G3 - desiccated and tested in dry condition.

A method for producing controlled fluoride release from an orthodontic bracket.

The aim of this study was to manufacture and test, in vitro, a novel modification to provide fluoride-releasing orthodontic brackets. Thirty-two orthodontic brackets were drilled to produce a recess (approximately 1.3 mm in diameter and 0.

The influence of microstructure on thermal response of glass ionomers.

This study was designed to determine the dimensional changes caused by thermal stimuli of glass ionomers with different glass/matrix ratios. Four cylindrical specimens were made for each of four powder/liquid ratios (3:1, 2.5:1, 2:1 and 1.

Response to thermal stimuli of glass ionomer cements.

Objectives: This study was designed to determine the dimensional changes of glass ionomers caused by thermal stimuli under both dry and wet conditions.

Methods: Eight cylindrical specimens (6 mm x 4 mm) were made (using a stainless steel mold) of each of the following materials: a conventional luting glass ionomer, two high viscosity restorative glass ionomers, a resin-modified glass ionomer and a resin composite which was used as a control. The thermal expansion characteristics were determined by a thermal mechanical analyzer (TMA) under wet and dry conditions by heating the samples from 25 to 70 degrees C at 10 degrees C min (-1).