The Influence of Reinforcement on Strain within Maxillary Complete Denture

Objectives: The purpose of this study was to examine the influence of an embedded cast metallic bar on the strain within the acrylic base of a maxillary complete denture.

Methods: A strain gauge was attached at each of three positions around the midline (labial; middle; and posterior) of the polished surface of a maxillary complete denture resting on a model of an edentulous residual ridge covered with 2mm-thick artificial mucosa (Fit Checker, GC, Japan). We tested four types of acrylic denture base (Parapress Vario, Kulzer, Germany): 1) without reinforcement (S); 2) with a chrome-cobalt bar (4mm wide x 0.5mm thick) from 1st molar to 1st molar (I); 3) with same chrome-cobalt bar on top of residual ridge (U); and 4) with the same bar from molar to molar and on top of the ridge (D). On 5 dentures of each type (S, I, U, D), we applied a vertical occlusal load of 49N to the 1st premolar and 1st molar regions, and used ANOVA for multiple comparisons of mean values.

Results: Significantly less strain (P<0.05) was recorded at the 1st premolars when dentures had either U-type or D-type reinforcements compared to dentures without reinforcement. When loaded at 1st molar position, strains in the middle and posterior position on the midline of dentures without reinforcement were “plus” and those with U-type and D-type reinforcement were “minus”.

Conclusions: A metallic bar embedded in the acrylic base reduces strain from occlusal stress on a maxillary complete denture.

This study was supported in part by a Grant-in-aid for Scientific Research (18791430) from the Japan Society for the Promotion of Science.