Clinical Evaluation of Retention of Metallic Versus Thermoplastic Resin Frameworks in Maxillary Distal Extension Cases

Background and Objective: Acetal resin has been introduced as an esthetic partial denture material. However, the retention of this material when compared to cobalt-chromium (Co-cr) frame works still unclear when applied clinically. Purpose: To evaluate the retention of (acetal resin) as compared to (Co-cr)frame works and clasps. Materials and Method: The present study is a randomized controlled trial that included 24 healthy patients with Kennedy class I partially edentulous maxilla and dentulous mandibles. The patients were selected from the out-patient clinic (Dep. of Prosthetic Dentistry, Minia University) and divided randomly into two equal groups according to the used denture base material; Group 1 received maxillary partial denture with (Co-cr) clasps and frameworks. Group 2 received maxillary partial denture with acetal resin clasps and frameworks. Retention of the prosthesis was evaluated at partial denture insertion, after 3, 6 and 12 months. Paired t-test was used at p ≤ 0.05 to assess the changes in the above parameter in each group. Student t-test was used to compare between the two groups. Results: Retentive force mean values of thermoplastic group were significantly lower than metallic group at denture insertion and at all follow up intervals. Conclusion: Acetal resin frameworks and clasps provide lesser retention values when compared to chrome cobalt. Clinical Implications: Although there was lesser retention power of acetal resin than Co-cr, further study has to be done regarding various thicknesses and designs of clasps and framework for its successful dental application.