Variation in mouthguard thickness due to different heating conditions during fabrication: Part 2

Abstract

The purpose of this study was to determine changes in the thickness of mouthguard sheets under different heating conditions during fabrication. Mouthguards were fabricated with polyolefin-polystyrene co-polymer (OS) and olefin co-polymer (OL) sheets (4.0-mm thick) utilizing a vacuum-forming machine under the following three conditions: (A) the sheet was moulded when it sagged 15 mm below the sheet frame (i.e. the normally used position); (B) the sheet frame was lowered to and heated at 30 mm below the top of the post and moulded when it sagged by 15 mm; and (C) the sheet frame was lowered to and heated at 50 mm below the top of the post and moulded when it sagged by 15 mm. The working model was trimmed to a height of 20 mm at the incisor and 15 mm at the first molar. Post-moulding thickness was determined for the incisal portion (incisal edge and labial surface) and molar portion (cusp, central groove and buccal surface). Dimensions were measured, and differences in the change in thickness due to heating condition were analysed using the Kruskal-Wallis test. Under condition C, OS and OL decreased in thickness from 0.36-0.54 mm to 0.26-0.30 mm, respectively, at the incisal portion and from 0.34-0.66 mm to 0.17-0.47 mm, respectively, at the molar portion. It may be clinically useful when moulding a mouthguard to maintain the thickness of the incisal and molar portions by adjusting the height of the sheet frame.

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

“…The model was left to dry for over 48 h at about 20.5°C in an air-conditioned room (8)(9)(10)(11)(12)(13)(14)(15)(16). A working model was fabricated using a silicone rubber (Correcsil Ò ; Yamahachi Dental Mfg., Co., Aichi, Japan) impression taken from a maxillary dental model (D16FE-500A-QF; Nissin Dental Products Inc., Kyoto, Japan), into which gypsum (New Plastone Ò ; GC Co., Tokyo, Japan) was poured.…”

“…A laser pointer was fixed to a three-dimensional coordinate measuring machine (192-201; Mitutoyo Co., Kanagawa, Japan) and used to measure the sagging distance (8)(9)(10)(11)(12)(13)(14)(15)(16). A separating medium was applied (at varnish TF; Shofu Inc.) to the model in preparation for pressure molding.…”

“…Measurement points for the thickness of the incisal portion were defined at the left and right central incisor positions as follows: five equally spaced points from the proximal to the distal end of the incisal edge; 10 points on the labial surface (including five equally spaced points from the cervical to incisal edge along a line located one-third of the distance from the proximal edge corresponding to the five points along a line located one-third of the distance from the distal edge). Significance was set to P < 0.05, and the power was set to 0.8 for all analyses (9,(13)(14)(15)(16). Measurements were taken once for each sample and were used in the analysis to determine the mean thickness and to calculate the reduction rate.…”

Influence of continuous use of a vacuum‐forming machine for mouthguard thickness after thermoforming

“…This timing is often recommended by the manufacturer because it is specific to the machine and to the thickness and material of the sheet. 15,[17][18][19] The temperature was constantly higher on the heated surface than on the non-heated surface. [13][14][15][16][17] Forming machines have either a single-sided or double sided heating mechanism.…”

“…18,19 This method led to a slow rise in sheet temperature, which was effective for controlling the uniform softening. 18,19 This method led to a slow rise in sheet temperature, which was effective for controlling the uniform softening.…”