Naoki Sakurai
A study on effect of occlusal interference concerning distance between upper and lower molars during lateral excursion of patients with internal derangement of TMJ J Jpn Prosthodont Soc, 1995;39:453�`463.
Abstract �@ The objective of this study is to investigate the quantitative occlusal condition of patients with internal derangement of the TMJ. To achieve this objective, the shape of the occlusal table of the upper and lower molars was scanned, reference points obtained and compared against the 3-dimensional movement of the mandible in a lateral occlusal position when a fixed incisal point is 2 mm distant from the intercuspal position. Eighteen subjects with internal derangement of the TMJ and eighteen asymptomatic subjects as control group were selected for this investigation. The following results were obtained: 1) the angle of the condylar path of the non-working side and the path of the lower molars on the non-working side was larger in the patients group than in the control group;�@2)the incl ination of the cusp slope of the upper molars of the non-working side in the patients group tended to be larger than that of the control group, especially in the second molar, where this difference was statistically�@sig nificant; 3)the interocclusal distance between upper and lower second molars in the non-working side of the patients group tended to be smaller than that of the control group,but it is statistically insignificant.

Naoki Sakurai,Shoji Kohno,Shuichi Nomura,Masahiro Suzuki.
The Distance between Upper and Lower Molars in a Lateral Occlusal Position on Patients with Internal Derangement of TMJ J.Jpn.Soc.TMJ 1995;7(1):222�`223.
Abstract The purpose of this study is to investigate the quantitative occlusal condition on patients with internal derangement of TMJ. The distance between each occlusal surface of upper and lower molars(also canines) at a lateral occlusal position was measured. The results were as follows: 1)The occlusal distance between upper and lower second molars in non-working side on the patients' group tended to be smaller than those of control group. 2)The occlusal distance of canines in working side on the patients' group tended to be larger than those of control group.

Hitoshi Sato* and Shoji Kohno*
Two Different Functions in the Masticatory Muscles during Voluntary Clenching Performances Dentistry in Japan, 32: 60-63, 1995.
Abstract Masticatory muscles function simultaneously as phasic positioner during generating biting force. Phase of functions as a phasic positioner and a force generator may be changed by the level mandibular stability and the degree of bite force. We therefore calculate activity index and asymmetry index under different levels of mandibular stability during bite force variations. As a result, 1) Activity index values for the masseter muscle were greater for the 100% MVC efforts than those for 30%MVC. 2) Asymmetry index of temporal muscle changed with stability of mandibular position in 30%MVC. While it did not change in 100% MVC. 3) Asymmetry index of masseter muscle did not change under different levels of mandibular stability. These results mean that 1) the temporal muscle is, at low clenching levels, working as a jaw positioner. 2) The temporal muscle is, at high clenching levels, working as a force generator. 3) The masseter muscle is, at any clenching level, working as a force generator.

Kohno S, Kobayashi H and Tsuchida Y
Function and dysfunction of SCM muscle during clenching and chewing movements In: Brain and Oral Functions (eds: Morimoto, Matsuya, Takada)
Abstract SCM muscle dysfunction and pain are frequently reported in patients with temporomandibular disorders and the pain was treated effectively by occlusal management. We examined the SCM muscle during clenching and chewing and reflex responses. During chewing, the activity of the SCM changed in proportion to the activity of the masticatory muscles and was changed with different texture of foods. The harder foods showed higher activities. And the activities of both muscles on the working side were higher than on the non-working side. This suggests that SCM can become more active to support an optimum head position when a larger occlusal force is applied during mastication. During clenching at the retruded jaw position, the SCM muscle showed higher levels of activity at approximately 20% lower bite force level than the efforts in the HP jaw position. It means that the muscle may become more easily fatigued by some parafunction habit in the retruded occlusal position. The developmental mechanism of SCM muscle activities during masticatory functions can be in two ways. One is the stretch reflex activity and the other is when the activities resemble to antagonistic and agonistic activities in relation to the jaw closing muscles.