Mechanical stability of orthodontic miniscrew depends on a thread shape.

Background/purpose: Primary stability of orthodontic miniscrew system is of great importance in maintaining stable anchorage during a treatment period. Thus, this study aimed to examine whether the thread shape of orthodontic miniscrew had an effect on its mechanical stability in bone.

Materials And Methods: Three different types of miniscrews (type A and B with a regular thread shape; type C with a novel thread shape) were placed in artificial bone block with different artificial cortical bone thickness of 1.

Influence of insertion depth on stress distribution in orthodontic miniscrew and the surrounding bone by finite element analysis.

We aimed to elucidate stress distribution in miniscrews and the surrounding bone when miniscrews inserted at different depths were implanted vertically or obliquely. The distributions of the equivalent stress on the screw surface and the minimum principal stress in the surrounding bone were calculated using finite element models. When the miniscrews were inserted vertically and obliquely, screw head displacement, greatest equivalent stress on the miniscrew surface, and absolute value of minimum principal stresses in the surrounding bone decreased with increasing insertion depth.

The influence of unilateral disc displacement on stress in the contralateral joint with a normally positioned disc in a human temporomandibular joint: an analytic approach using the finite element method.

Objectives: To investigate the influence of unilateral disc displacement (DD) in the temporomandibular joint (TMJ) on the stress in the contralateral joint, with a normally-positioned disc, during clenching.

Study Design: A finite element model of the TMJ was constructed based on MRI and 3D-CT of a single patient with a unilateral DD. A second model with bilateral normally-positioned discs served as a reference.

Three-dimensional finite element analysis of cartilaginous tissues in human temporomandibular joint during prolonged clenching.

Objective: Bruxism, the parafunctional habit of nocturnal grinding of the teeth and clenching, is associated with the onset of joint degeneration. Especially prolonged clenching is suggested to cause functional overloading in the temporomandibular joint (TMJ). In this study, the distributions of stresses in the cartilaginous TMJ disc and articular cartilage, were analysed during prolonged clenching.