Effect of relining method on dimensional accuracy of posterior palatal seal. An in vitro study

The posterior palatal seal contributes to the retention of the complete denture. Distortion of this area can occur during reline procedures. The purpose of this study was to evaluate the dimensional accuracy of various denture relining methods and materials on the maxillary posterior palatal seal area.

A stainless steel cast was constructed from a maxillary edentulous cast. Fifty identical complete dentures were fabricated on 50 definitive casts made from the original metal cast. Five relining methods and materials were evaluated during this study, in regards to posterior palatal seal distortion: (I) laboratory conventional heat-polymerizing method (Lucitone), (II) laboratory heat/pressure-polymerizing method (SR-Ivocap), (III) laboratory autopolymerizing method (Perm), (IV) chairside autopolymerizing method (Tokuso Rebase), and (V) chairside light-polymerizing method (Astron). The dimensional changes of the posterior palatal seal areas were determined by placing a low-viscosity silicone impression material between the metal cast and the tissue surface of the relined dentures. The silicone thickness was measured at five predetermined points, under a measuring microscope. Statistical analysis was performed using descriptive statistics, one-way analysis of variance, and Student-Newman-Keuls tests (alpha= 0.05).

The gap at the posterior palatal seal area ranged from 68.76 to 331.55 microm, when measured at the five predetermined points. Group IV exhibited the smallest mean gap (137.62 microm) and Group I revealed the largest mean discrepancy (192.35 microm). The different relining methods and materials presented statistically significant differences (p < 0.0001).

The chairside autopolymerizing method exhibited smaller gap recordings than the rest of the tested complete denture relining methods.