Effect of implant support on mandibular distal extension removable partial dentures: relationship between denture supporting area and stress distribution.

PURPOSE: This study explored the relationship between implant support and the denture-supporting area by comparing the stability of an implant-supported distal extension removable partial denture and a conventional distal extension removable partial denture.

METHODS: A model simulating a mandibular bilateral distal extension missing (#34-37 and #44-47) was fabricated using silicone impression material as soft tissue (2 mm thick) on an epoxy resin bone model. The denture base was reduced by 5 mm cutting part of both the retromolar pad and the lingual border. Loads of up to 5 kg were applied, and the pressure and displacement of the RPDs were simultaneously measured and analyzed using the Wilcoxon test (α<0.05).

RESULTS: The pressure on the bilateral first molar and the middle areas of the implant-supported distal extension removable partial denture (ISRPD) was significantly less than on the conventional RPD (CRPD). As the supporting area of the denture base decreased, the pressure and the denture displacement of the CRPD were greater than for the ISRPD.

CONCLUSION: This study indicated that implant placement at the distal edentulous ridge can prevent denture displacement of the distal extension bases, regardless of the supporting area of the denture base.