Clinical Negative Pressure Measurement after Border Molding Procedure

Border molding of the custom tray's edge is an important stage in the treatment of an edentulous jaw that determines the stability of prosthesis at rest and function. Solid, thermoplastic and silicon impression materials may be used in border molding. After bolder molding procedure, the negative pressure between the custom tray and the prosthetic field is created. This is an informal indication for a good impression.

To compare the negative pressure created after border molding procedure with different impression materials.

35 patients (17 men and 18 women) aged 51 to 87 years with a complete edentulous upper jaw were examined. New clinical method for negative pressure measurement was created.  We used a special custom tray with palatal adaptor and a pump. Two groups of impression materials were tested:  thermoplastic (Kerr impression compound green sticks, GC Iso functional sticks) and silicones (Detaseal function, Sta-seal f). Statistical analysis was performed using ANOVA, confirmed by the absolute value analysis used to compare negative results, and a log transformation analysis for greater precision and also for negative data comparison.

A statistically significant difference was found between the two thermoplastic materials - GC Iso functional sticks and Impression compound green sticks. The mean group difference between these materials was 0.049 bars. There was no statistically significant difference between the other groups of materials.

Quantitative measurement of negative pressure, created between the custom tray and the prosthetic field is entirely possible under clinical conditions.