Finite Element Analysis of Elastic Stresses on Oral Mucosa and Cortical Bone by Maxillary Poly (Etheretherketone) (PEEK) Removable Partial Denture (RPD)

Abstract

Background- Use of Polyetheretherketone (PEEK) for the removable partial dentures (RPD)frameworks is gaining popularity. But weather it distributes the stresses in a similar way like cobalt-chromium alloy (CoCr) or titanium alloy (Ti) is still unclear and needs assessment.

Purpose: The aim of the study was to evaluate the amount of stress distribution on oral mucosa and cortical bone of alveolar ridge by maxillary poly (etheretherketone) (PEEK) removable partial denture (RPD) using 3-dimensional finite element models and compare it with stress generated by conventional cobalt-chromium (Co-Cr) RPD and titanium (Ti) RPD, in distal extension cases.

Materials and Methods: Patient’s intraoral data were obtained via CBCT and master model scan. Virtual RPD framework model and underlying oral mucosa with cortical alveolar ridge was produced for a Kennedy Class II arch modification 1, having first pre-molar as primary abutment. Designing was done following conventional guidelines, using 3Shape dental system. RPD frameworks were designed. Three materials were considered, one with PEEK, second with Co-Cr and third Ti. Movement of the rest on the tooth-supported side was restricted in all directions. For calculating the elastic stresses on mucosa, movement of the alveolar surface of the mucosa and the occlusal rest on the abutment adjacent to the edentulous ridge was fixed in a vertical direction and for stresses on cortical alveolar bone the movement of oral mucosa was fixed in all direction along with the occlusal rest on the abutment adjacent to the edentulous ridge. The Vertical and buccally oblique biting forces were applied simultaneously on each of the locations representing two missing teeth. The FEA was done for analyzing the stress transferred from the RPD frames.

Results: In the 3 tested materials, framework made of PEEK has the lowest maximum von Mises stress followed by CoCr and Ti- 18.736 MPa,66.657 MPa and 68.323 MPa respectively, greatest maximum von Mises stress on the mucosa0.12625MPa and alveolar bone 1.6369 MPa. PEEK has the largest displacement of the framework (free-end displacement of the framework)0.039954 mm, which was larger than CoCr alloy (0.024367mm) and Ti alloy(0.004607mm) and its deformation along with the deformation of complete model assembly.

Conclusion- PEEK framework has the maximum displacement under load which is not good for RPD stability, also as it conducted more stress on mucosa and alveolar bone, which will result in fast resorption of residual alveolar ridge.