Shape change in mouthguard sheets during thermoforming – part 2: effect of the anteroposterior position of the model on mouthguard thickness

Abstract

The results showed that the thickness reduction was large when the distance from the model to the frame was small. This demonstrates the importance of centering the sheet and the model to achieve the most stable molding when positioning the model in the forming unit.

Effect of the anteroposterior position of the model on fabricated mouthguard thickness: Part 2 Influence of sheet thickness and material

“…Mouthguard thickness should generally be at least 3 mm to sufficiently reduce the force of impacts . However, the thickness reduction of fabricated mouthguards is remarkable as about 35%‐60% . In particular, the thickness reduction during the second stage of formation is large.…”

“…Previous studies have shown that the shape change of the sheet occurs in both the first and second stages . The shape change in the first stage when the appropriate softening temperature was reached tended to increase slightly more in the central region than at the sheet periphery, and noticeable changes did not occur in the center (lowest point of the sheet sag), so the difference was only about 5% in this area.…”

“…A working model was fabricated using a silicone rubber (Correcsil ® , Yamahachi Dental Mfg., Co., Aichi, Japan) impression taken from a maxillary dental model (D16FE‐500A‐QF, Nissin Dental Products Inc., Kyoto, Japan), into which dental gypsum (New Plastone ® , GC Co., Tokyo, Japan) was poured. The gypsum was allowed to harden for 60 minutes, and then it was removed and trimmed (Model trimmer MT‐6 ® , Morita Co., Tokyo, Japan) to a height of 25 mm at the incisal edge of the maxillary central incisor and to a height of 20 mm at the mesiobuccal cusp of the maxillary first molar . The model was left to dry for over 48 hours at about 20.5°C in an air‐conditioned room, and a separating medium was applied (at varnish TF, Shofu Inc., Kyoto, Japan).…”

“…The sheet was then removed with scissors (HSB 630‐10, Karl Hammacher GmbH Co., Cologne, Germany). Six samples were produced for each condition …”

“…Significance was set to P < 0.05, and the power was set to 0.8 for all analysis. Overall, a significant difference was considered to be present when both items were satisfied …”