The aim of this study was to examine the infl uence of the preparing condition of the working cast and mouthguard sheet on the thickness of mouthguard. Methods: We used a mouthguard sheet (127 127 3.8 mm). The sheets were formed by a vacuum former when they were heated until they were hung 1.5 cm from baseline. The thickness of the mouthguard sheet was measured at the part fi tted to anterior and posterior teeth. As the preparing conditions of the working cast, relations among the measurement point, setting position, and temperature of the working cast as well as among measurement point, setting position, and angle of the working cast were analyzed by Three-way ANOVA. As the condition of the mouthguard sheet, the relation between the measurement point and temperature of the sheet was analyzed by Twoway ANOVA. Results: The thickness at anterior teeth became bigger at the condition that the working cast was set in the posterior position, and that of posterior teeth became bigger at the condition that the working cast was set in the center position. The thickness at anterior and posterior teeth became bigger at the condition that the angle of the working cast was set 80. The thickness at anterior teeth became bigger when the temperature of the mouthguard sheet was high. Conclusions: These results suggest that the thickness of the mouthguard could be maximized when the position of the part of the working cast that need to keep the thickness was set in the center, the angle of the working cast was set to 80 , and the temperature of the mouthguard sheet was high.

The angle of the working model at the labial surface of the central incisor and the base of the working model should be maintained at an acute angle (e.g., 85°) to control the thickness at the central incisors and the first molars of pressure-formed mouthguards.

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The aim of this study was to investigate differences in the thickness of the mouthguard sheet according to the holding conditions during heating. The material used in this study was Sports Mouthguard (3.8 mm thickness), and two holding conditions of the sheet were undertaken: one was the condition that the sheet was held all around the periphery and the other was that the sheet was held at only four points. The sheets were formed using a vacuum former when the sheets were heated until they hung 2.0 cm from the baseline. We measured the thickness of each part of the mouthguard and calculated the ratio of changes in the thickness. The difference in the thickness by the holding conditions at the area of the sheet that fitted over the anterior teeth, palate, and posterior teeth was analyzed by the paired t-test. The results showed that the thickness of the sheet differed statistically and significantly at the regions of the sheet that fitted over the anterior teeth and posterior teeth (P < 0.01) and the palate (P < 0.05) according to the holding conditions of the sheet. The thickness of the condition that the sheet was held all around the periphery was thinner than that of the condition that the sheet was held at only four points. These results suggested that the thickness of the sheet was maintained by holding the sheet only at four points, and this new method could be an effective way to maintain the thickness of the mouthguard in clinical use.

JapanSUMMARY Stabilisation splint therapy has long been thought to be effective for the management of temporomandibular disorders (TMD). However, the superiority of stabilisation splint therapy compared to other TMD treatments remains controversial. The aim of this study was to determine the efficacy of stabilisation splint therapy combined with non-splint multimodal therapy for TMD. A total of 181 TMD participants were randomly allocated to a non-splint multimodal therapy (NS) group (n = 85) or a nonsplint multimodal therapy plus stabilisation splint (NS+S) group (n = 96). Non-splint multimodal therapy included self-exercise of the jaw, cognitive-behavioural therapy, self-management education and additional jaw manipulation. Three outcome measurements were used to assess treatment efficacy: mouth-opening limitation, orofacial pain and temporomandibular joint sounds. A two-factor repeated-measures analysis of variance (ANOVA) was used to evaluate the efficacy of the two treatment modalities (NS vs. NS+S), and

抄 録 目的：スポーツ時の顎口腔領域の外傷予防には，マウスガードの装着が有効である．本研究は，吸引成形 後のシート各部の厚みについて，色の異なる 2 種のシートを用いて比較検討した． 方法：マウスガードシートに 10 mm 四方の格子を印記し，各格子の厚さをメジャリングディバイス Ⓡ を用 いて測定した．マウスガードシートは白色(MG-W)および紫色(MG-P)のものを用いた．作業用模型 は上顎有歯顎模型をシリコンラバー複製印象材を用いて印象採得後，硬質石膏を注入して作製し，上顎中 切歯切縁で 20 mm，上顎第一大臼歯近心頬側咬頭で 15 mm になるようトリミングしたものを使用した． 加熱条件は，基底面からの垂れ下がり距離が 15 mm のもの(条件 A) ，30 mm のもの(条件 B) ，45 mm のもの(条件 C)の 3 条件とした．2 色のマウスガードシート各部の厚みの違いを t 検定および Wilcoxon 符号付順位和検定を用いて分析を行った． 結果：シートの模型圧接部は，すべての部位で厚みが減少した．前歯部および口蓋部では，すべての加熱 条件において MG-W のほうが MG-P に比較して厚みの変化率が大きかった (p<0.

Purpose: Thermal shrinkage of mouthguard sheet material influenced the thickness after forming. The aim of this study was to investigate the elongation and thickness of mouthguard sheets in relation to the thermal shrinkage of the mouthguard sheet material. Methods:Cross stripes (10×10 mm) were printed on mouthguard sheets. The length in the anteroposterior and bilateral direction was measured using vernier calipers, and the thickness of each cross stripe area was measured using a measuring device. The plaster cast was trimmed to the height of 20 mm at the upper central incisor and 15 mm at the upper first molar. The sheets were heated until they sagged 15 mm from the baseline. Two positions of the sheet were compared: the sheet became parallel (condition A) or vertical (condition B) direction to the thermal shrinkage of the mouthguard sheet material toward the cast. The difference in the ratio of change of the elongation and thickness between two conditions was analyzed by paired t-test and Wilcoxon signed-rank test. Additionally, the relationship between the elongation and thickness of the sheets was investigated by regression analysis. Results:The elongation in the part of the sheet fitted to the anterior teeth and posterior teeth of condition A was smaller than that of condition B. The thickness in the part of the sheet fitted to the palate and posterior teeth of condition A was smaller than that of condition B. The relationship between the elongation and thickness of mouthguard sheets was modeled by a quadratic equation. Conclusion: This study suggests that the thickness of the part of the sheet fitted to the palate and posterior teeth, which was parallel in direction to the thermal shrinkage of the mouthguard sheet material toward the plaster cast, was thinner than that of the vertical direction.

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