Stress distribution patterns of implant supported overdentures-analog versus finite element analysis: A comparative in-vitro study.

AIMS AND OBJECTIVES: The aim of this study was to asses & compare the load transfer characteristics of Ball/O-ring and Bar/Clip attachment systems in implant supported overdentures using analog and finite element analysis models. METHODOLOGY: For the analog part of the study, castable bar was used for the bar and clip attachment and a metallic housing with a rubber O-ring component was used for the ball/O-ring attachment. The stress on the implant surface was measured using the strain-gauge technique. For the finite element analysis, the model were fabricated and load applications were done in a similar manner as in analog study. RESULTS: The difference between both the attachment systems was found to be statistically significant (P<0.001). CONCLUSION: Ball/O-ring attachment system transmitted lesser amount of stresses to the implants on the non-loading side, as compared to the Bar-Clip attachment system. When overall stress distribution is compared, the Bar-Clip attachment seems to perform better than the Ball/O-ring attachment, because the force was distributed better.

Survey on Bolton's Tooth Size Analysis as Applied to Artificial Teeth.

The presence of proportionate teeth size in either arch is a must to obtain an ideal occlusion with good alignment, ideal overjet, ideal overbite and Class I molar relationship. The above facts made us think and to know if this proportion between maxillary and mandibular teeth existed in artificial teeth also? Hence, a survey is undertaken to study the tooth size relation in commercially available artificial teeth. From the results of the present study it was concluded that the anterior and the overall ratios are slightly varied when compared to the standard Bolton's ratios. On comparison the difference between the study ratios and the standard Bolton's ratios were not statistically significant.