Hitoshi Kato

The relationship between bite force and oral sensation during biting in molars

BACKGROUND In prosthodontic treatment, the occlusal form should be designed such that bite force is applied at the position that has higher load-bearing capacity and is comfortable for the patient. The purpose of this study was to clarify the differences in bite force and occlusal sensation with different loading positions on the occlusal surface. METHODS Twelve healthy subjects were recruited for this study. Bite force and occlusal sensation were measured at five loading points on the upper and lower left first molars. Occlusal sensation was evaluated using a Visual Analogue Scale (VAS). RESULTS Bite forces on the lingual side of the upper first molar and the buccal side of the lower first molar were significantly higher and VAS scores were significantly lower, i.e. the subjects felt less discomfort during biting on the buccal side of the upper first molar and the lingual side of the lower first molar compared to the other side of each molar. CONCLUSIONS Loading on the occlusal surfaces of the functional cusps of the upper and lower first molars produces more load-bearing capacity and is more comfortable than loading on the non-functional cusps.

Observation of Intraoral Food Flow in Mastication.

咀嚼の主要な機能である食塊形成の過程を解明するためには, 咀嚼時の食物動態を観察することが重要である.本研究では, シリコーン印象材のパテタイプを食物に見立てて擬似咀嚼を行わせ, 咀嚼後の代用食品の形状を観察して咀嚼時の食物動態の概要について, 以下の結論を得た.1.咀嚼中の食物は上下顎臼歯の被蓋咬頭の内斜面に沿った方向へ流出している.2.頬, 舌の協調機能による咬合面への食物の乗せ方には, 舌側から適量つつ咬合面に乗せて咀嚼を行う分割咀嚼と, 全量を咬合面上に乗せて咀嚼を行う一括咀嚼の2通りの咀嚼様相がみられる.3.正常被蓋側では分割咀嚼が行われ, 咀嚼機能は円滑に営まれている.4.交叉咬合側では一括咀嚼が行われているが, これは機能的には正常とみなし難い.