RESUMO
PURPOSE: The aim of this study was to evaluate the labio-lingual alterations of the alveolar bone where the implant was placed immediately after tooth extraction. MATERIALS AND METHODS: Implants were placed immediately after tooth extraction on anterior alveolar ridges in the maxilla and mandible. The pin-guide system was used to help determine the location and path of implants during the surgical process. The horizontal distance from implants to the outer border of alveolar bone was measured at the rim and middle of the implants in the cone beam computed tomography images. The alteration of alveolar bone was evaluated comparing the horizontal distances measured immediately after surgery and 3 months after surgery. RESULTS: The results show that more resorption occurred towards the labial bone than the lingual bone in the maxilla. A similar amount of labial and lingual bone resorption was observed in the mandible. CONCLUSION: Considering the horizontal alteration of alveolar bone, labio-lingual positioning of the implant towards the lingual bone in the maxilla and at the center of the alveolar ridge in the mandible is recommended when it is placed immediately after tooth extraction.
RESUMO
The stress distribution generated in the surrounding bone was calculated and compared for various geometry of the dental implants by means of the finite element methods. The models were designed to represent the screw type endosseous implants (varing the size, shape, direction of the screw thread and the angle of the body) with supporting bone and the cylinder type endosseous implants (varing the lower portion-Round type, tapered type) with supporting bone. Static mean bite forces were applied 100N vertically and 25N horizontally on the center of the implant and three dimensional finite analysis was undertaken using software ANSYS 5.1 Version. The result demonstrated that different implant shape leads to significant variations in stress distribution in the bone. In the case of variation of the screw size, direction and shape the implant model with normally directional and triangular screw implied lower stress than with upper directional or lower directional and quadrangular screw but among models a different screw size, within a variation of 0.2mm there was no meaningful difference in maximum stress. In the case of variation of angle of body the straight implied lower stress than the tapered. As a result of analysis of cylinder type, the implants with larger radius of curvature of the round form and larger diameter of the tapered form implied lower stress.