The magnitude and distribution pattern of stress on implant, teeth, and periodontium under different angulations of implant placement for en masse retraction: A finite element analysis

Abstract

Context: This study was undertaken to evaluate the magnitude of reactionary stresses and their pattern of distribution on implant, teeth, cortical bone, cancellous bone, and periodontal ligament (PDL) so as to determine the most favorable angle for the placement of mini implant and the most favorable force system for en masse retraction. Aims: The aim of this study is to obtain the ideal force system for en masse retraction using mini implant and to determine most favorable angle for implant insertion. Materials and Methods: DENTASCAN was used to fabricate a three-dimensional finite element model of the maxilla. Three models were constructed with different implant angulations, i.e., 45°, 60°, and 75°. Each model was applied 150, 200, 250, and 300 g of load. The results were analyzed using ANSYS software. Results: Maximum stress was observed at the head of implant at the point of attachment with the retraction spring. In cortical bone and cancellous bone, stress was distal to bone-implant interface. In PDL, maximum stress developed at the apex of lateral incisor root. Conclusion: For en masse retraction, the most favorable angulations for implant placement are 60°, and ideal force system is in the range of 200–250 g. Force levels above 300 g will possibly produce deleterious effects on PDL, cancellous bone, and teeth.