Impression pressures against teeth in a partially edentulous model with a mobile tooth: influence of impression tray design

Abstract

The purpose of the present study was to examine the effect of custom tray designs on local pressures against teeth during the impression procedure. In a previous study, a partially edentulous simulation model with a mobile tooth was used, and the effect of custom tray designs on the displacement of the mobile tooth was examined during the impression procedure. Based on that study's results, we have assumed that the differences in impression pressures between the labial and the lingual sides of a mobile tooth could either cause or affect displacement. The present study was undertaken to determine the local impression pressures against each side of three anterior teeth, including one mobile tooth, using the same simulation model and the same custom trays as in the previous study. It was found that the local pressures exerted against teeth during the impression procedure were affected by the custom tray designs and varied according to the coronal shape, axis inclination and location of the teeth.

Effect of different labio‐lingual spaces in tray designs on the displacement of and pressure against a mobile tooth

“…The space affects the impression pressure occurring during impression procedure, which would displace the tooth and ridge mucosa. It was reported that using trays with a thicker space for impression materials lessened the impression pressures (3, 7–9). Furthermore, Nishi et al.…”

“…The simulation models and devices for measuring displacement of the mobile tooth and impression pressure against the subject teeth, which were used in previous studies (2, 3), were prepared in the present study. The two simulation models were prepared using a simulated periodontal ligament made of silicone rubber for the left central incisor (mobile incisor) in a mandibular plastic model with six anterior teeth (Model 550)*.…”

“…The impression procedure in the present study was the same as in previous studies (2, 3). The seating speed of the tray was regulated at 100 mm min –1 using a digital load measurement apparatus (Test Stand Model 1310DW)**.…”

“…As a result, the impression pressures of each subject tooth were greater against the lingual side than the labial side with all custom tray designs. The thicker space and perforated holes on only the lingual side or both sides in the custom trays as well as in the first study lessened the impression pressures against the labial and lingual sides of each subject tooth and their differences (impression–pressure differences) (3).…”

“…Two previous studies were performed to examine the effect of impression custom tray designs on the displacement of mobile tooth and local impression pressure against mobile tooth, using partially edentulous mandibular simulation models with six anterior teeth containing a mobile incisor (2, 3). Custom trays were designed by altering the thickness of overall spaces for the impression materials and the perforated holes as escapeways in the region of the remaining tooth arch with the mobile incisor.…”