An imaginary lateral incisal path computed by means of the kinematic formulae for mandibular movement derived by the authors^{8, 9)}, using measured condylar path and angle of hinge rotation data and assuming that the working condyle travels straight laterally on the intercondylar axis, was called“neutral line”. Correlation between the amounts of sagittal deviations of measured lateral incisal paths from their neutral lines and the sagittal displacements of working condylar path were tested. The correlation coefficients between the two was larger than 0.97, at the significance level of P=0.001¹⁰⁾.
Therefore, there are possibility that one can directs working condylar path straight laterally on the intercondylar axis, by treating the lateral incisal path so as to coincide with the neutral line.
It is suggest ed that the Condylar path, as far as the workingside is concerned, may not be fixed and may change or be changed.

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Success rate of porcelain laminate veneers in the International Dental Academy Clinics, Tokyo, was 98.0% among 711 teeth of 251 patients treated during the period of 1985-1992.
The total number of failured teeth was 14, among which veneers on 6 teeth fell down, dental pulps in 5 were gangrenous, and veneers on 3 were broken.

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Beginning with this paper, I would like to discuss the fundamentals of clinical gnathology for those who would like an introduction to this field.
Gnathology was first introduced to Japan in 1960 by Ben Papone. Since that time gnathology spread rapidly throughout the world through the efforts of P.K. Thomas and has contributed greatly to the development of present day modern dentistry. This is due to the fact that the scientific basis and physiologic superiority of gnathology has been recognized. In contrast, together with the spread of gnathology, there have been several report on its detrimental effects.
Since gnathology puts considerable emphasis on the use of the pantograph and articulator, it has often been thought of as mechanical and non-physiologic. This view must be rejected as mistaken and based on ignorance of the truth about ganthology.
Mistaken beliefs like this are common throughout the world today. This tendency is particularly strong in the dental community in Japan where medicine is dominated by an inferior social health insurance system worse than any in the world. In the United States and Europe gnathology has already spread, and has become widely incorporated into daily clinical practice. Gnathology is even being practiced without the awareness that it is gnathology.
In preparation for the clinical aspects which will be covered next, while emphasizing the problems of introducing gnathology in Japan, the social background of that time, physiological aspects, the importance of periodontal tissues, and in particular high technology, I would like to discuss our predecessors who built up the tradition of gnathology by relentlessly pursuing the elevation of precision (physiology) and simplicity.

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