Measurement of periapical pressure created by occlusal loading.
AIM: To develop an in vitro model in which the pressure in the periapical tissues can be measured during loading. METHODOLOGY: Extracted human maxillary central incisors were embedded in resin blocks that had physical characteristics similar to those of bone and periodontal ligament. Each tooth was loaded with 20, 40, 50, 60, 75, 85, 100, 200, 300 and 450 N vertical forces from the incisal edge of the crown on three consecutive occasions. A minute resistor embedded in the periapical space was used to detect apical pressure changes during occlusal loading. The ratio of apical pressure changes (DeltaP) to the loading force changes (DeltaF) was calculated. RESULTS: The periapical pressure detected was in direct proportion to the loading force. The mean value of DeltaP/DeltaF was 5.994 kPa N-1 (SD = 2.04). CONCLUSIONS: Direct proportionality was found between the coronal loading and the apical hydrostatic pressure. The DeltaP/DeltaF ratio determined in this study makes it easier to estimate the apical hydrostatic pressure values during occlusal loading of single-rooted teeth. In this study, the apical pressure generated under occlusal loading was the same magnitude as that estimated with the finite element method.