Mandible is a long bone which is bent in the form of a 'U' or bow, supported and articulated with the cranium by means of muscles and ligaments. These muscles, tendons and ligaments attached to the mandible exert force, which causes change in the shape of the mandible at different levels of movement of the jaws. A medial flexure of mandible occurs during wide opening of mouth with the amount of flexure depending on the degree of jaw movement. This mandibular flexure, though minimal, has a profound influence on cross-arch restorations and patients with subperiosteal implants. This article describes the various facts and consequences of mandibular flexure.

Statement of problem:Given that meticulous implant prosthodontic procedures are recommended to obtain the best possible intraoral fit, the die systems used for multi-implant casts warrant further investigation. Die stone expansion and errors introduced by removable die casts may exceed the accuracy required for the passive fit of implant prosthesis. Purpose:The purpose of the study was to evaluate the linear dimensional accuracy between the implant master die and three conceptually different die systems, such as Pindex system, Accu-trac precision die system and conventional brass dowel pin system. Materials and methods:Thirty impressions of implant master die were made with polyether impression material. Ten experimental implant casts were fabricated for each of the three different die systems tested: Accu-trac precision die tray system, Pindex system and conventional brass dowel pin system. The solid experimental casts were sectioned and then removed from the die system 30 times. Linear distances between all six possible distances were measured from one center of the transfer coping to the other, using a coordinate measuring machine in millimeters up to accuracy of 0.5 microns. Data were tabulated and statistically analyzed by binomial nonparametric test using SPSS version 15.Results: Significant differences were found for distance A-B (p = 0.002), A-C (p = 0.002), A-D (p = 0.002) and B-D (p = 0.021) in conventional dowel pin system however, for Accutrac precision die tray system it was significant only for distance A-D (p = 0.002) but for Pindex system it was nonsignificant for all the distances measured. Conclusion:Within the limitations of this study, use of Pindex system is recommended when sectioned dies are needed for a multi-implant retained prosthesis.

Dental implants have revolutionized the field of dentistry. Its immense popularity and wide acceptance has led to a point, where it has become a part of routine treatment plan in oral rehabilitation. For the success of implants, a presurgical treatment planning is of utmost importance. To aid this, diagnostic imaging plays a vital role. There are various modalities of imaging which will aid in placing the implant in an appropriate location with relative ease and also get a predictable outcome. This article focuses on the various imaging modalities available currently and their clinical applications. Modalities described are intraoral radiography, cephalometric radiography, panoramic radiography, conventional tomography, computed tomography, cone-beam CT and magnetic resonance imaging. The final selection of one these imaging modalities are dependent on the operator choice based on the patients need.

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