The effect of a custom edentulous impression tray on lingual sulcus depth

An acrylic resin custom edentulous impression tray and standardized irreversible hydrocolloid impression technique were used. Ten impressions were made, after which the lingual border of the tray was reduced by 1.5 mm before the next series of impressions was made. This was done three times. Impressions were cast in a miter box. The plaster blocks so obtained were sectioned in the (a) retromylohyoid region, (b) 10 mm anterior, and (c) in the region of the mental foramen. In the retromylohyoid region there was a significant difference between the flange length after each reduction of the custom tray (p less than 0.01). Ten millimeters anteriorly the differences after each reduction except between the first and second reduction were less significant. In the region of the mental foramen there was a significant difference after the first reduction, but there was no significant difference between the flange lengths obtained thereafter.