In vitro stress analysis of class II Kennedy conventional design and side plate with OT attachment

Abstract

Aim of the work The purpose of this study was to compare stress induced by the conventional design of lower unilateral free-end saddle and side plate with extra-coronal attachment (OT Cap attachment) and record the micro-strains induced by this stress. Materials and methods Strain gauge technology was used for strain analysis. A two-layer epoxy resin model with a unilateral distal extension base was used in this study with the second premolar as the last standing abutment. Model A: A lower metallic partial denture was made with an RPI clasp as a direct retainer on the second premolar and a double Aker clasp for cross-arch stabilization on the 1st and 2nd molars of the dentulous side, and the lingual plate served as a major connector. Model B: Lower metallic partial denture was made with the extra-coronal attachment (OT Cap attachment) as a direct retainer on the second premolar splinted with the first premolar by crowns. Stresses were measured vertically and obliquely at the buccal and lingual sides of the lower 2nd premolar, the edentulous ridge in the lower 2nd molar, and the double Aker in the dentulous side of model A. However, stresses were measured vertically and obliquely at the buccal and lingual side of the lower 2nd premolar and the edentulous ridge in the lower 2nd molar of model B. Data were collected, tabulated, and statistically analyzed using the SPSS software program. Results The present study revealed that stresses recorded at the abutment teeth and the ridge in the area of the lower second molar were higher in the case of conventional RPD than in OT attachment and the micro strains recorded around the abutment tooth were much more than micro-strains recorded around the residual ridge. Conclusions Mandibular partial denture using OT attachment can be considered as a prosthetic option for the management of class II Kennedy classification as it can improve the integrity of the alveolar bone of the abutment tooth and the residual ridge. Splinting of abutments reduces the stresses located in the buccal and lingual aspects of the abutment connection between the abutment and the OT attachment allowing better distribution of the stresses between the abutment tooth and the ridge vertically and obliquely.