Recently the importance of creating “the conditions of excellent chewing for a long time”is being stressed more and more at dental clinic. Oral surgery, endodontics, periodontics, orthodontics and pzosthodontics are treated as one. But occlusion is the key to it. The theory and technic of the occlusion are only seldom applied at the clinic because of difficulty and misunderstanding that valuable instruments are always necessary. The diagnosis and treatment of occlusion should be performed smoothly at the clinic on a day to day basis thus the technic should be made more simple, precise and done more quickly. Condyler path inclination of a semiadjustable articulator is adjusted by check bit, results differ from dividual dentists. Thus a pantograph is thought, to be a good idea to adjust the semiadjustable articulator. At the same time, it is also necessary to judge which period of the pantograph survey line is the best. There is not a definite standard to adapt the occlusal plane at the clinic. HIP plane being established considerably stable three points are taken as the occlusal plane for both a dentulous jaw and an edentulous one. Protrusive condyler path and the occlusal plane take the angle of twenty-six degrees on average. HIP plane can be applied for not only diagnosis but also treatment. Most of the occlusal plane runs parallel with Camper's line after the treatment. Though condyler path, incisal path and occlusal plane, are known to be important for making therestoration harmonize with the mandibulor movement, its untantunate the restoration is still often made through trial and error at the clinic. In future it is hoped that their relationship can be more accurately detined to be explined the relation between with them. Chewing means not only just a faculty but an efficient one and it is the aim that all the treated teeth must be healthy for ever. The more dentists perform the treatment based on the occlusion, the more patients will be helped. It is the real point of gnathology.
From about the middle of this century untill today the mechanical culture of our society has developed taster ever than before. Certainly, during this period prosthodontics have progressed remarkably. There has been considerable advance in the field of the articulator. Especially, Stuart's Articulator with it's pantograph although has remained basically the same, there have been improvements since 1955. Today is extremely accurate as compared with other articulators and it is also quite reliable and valued highly by gnathologists. But for everyone, harmonious restoration can not always be achieved by using Stuart's Articulator. It is impossible to make exact restoration unless it is used with the correct knowledge. Consequently, Stuart's Articulator sometimes disappoints and moreover, gnathological practice is disliked. Diagnosis is most important at the daily practice. The articulator is used as one of the methods of diagnosis, centric relation and centric record are important too. The centric relation is always a standard for transferring upper and lower models to the articulator on the occasion of the diagnosis, restorative working and remounting. In brief, a good restoration will only be achieved with taking a correct centric relation, even if the most accurate articulator is used.
It is the final aim of gnathology to give physiological occlusion to the patient. However, generally, intercuspal occlusal position of the upper and lower jaws always avoid the interference of cusp, so that the occlusion is not recognized as a centric relation one. This is clarified according to the result of the occlusal diagnosis of about five hundreds cases. It was found there may be some complaints of disharmony or discomfort for the restoration in the intercuspal position without occlusal diagnosis. Consequently, at first, the occlusal diagnosis of the centric relation is performed, then, the restoration must be set in accordance with the centric relation occlusion. Many patients suffering from occlusal disease for a long period time may be cured by setting the harmonious restoration of the centric relation. Dentistry is valued more highly, and is more reliable. Thus it should be the first step for gnathology at the daily clinic always at the primary stage of treatment.
We started from the hypothesis that the oral muscles have a role in determining the direction in which the teeth will develop, and in maintaining the stability of the dental arches. According to this hypothesis the teeth are equilibrated between the tongue, the lips and the oral muscles. In order to understand the development of occlusion, Dr. Cauhépé has built a strain gauge apparatus with which the hypothesis was confirmed. The present article will show how this hypothesis was confirmed.
There is no definite rule to change or arrange anterior guidance for oral rehabilitation. Therefore, the anterior guidance must be fixed in order to adapt the neuromuscular system, through trial and error. Naturally, the matters of phonetics and esthetics are just as important as this. In the case, when oral rehabilitation is treated according to the results of the examination, of the occlusal diagnosis and of the wax-up for the diagnosis, then, it is necessary to arrange the anterior guidance, so it can be settled by trial and error. In addition, as several pantograph survies are made, then the effect can be confirmed. Thus a comfortable restoration can be set.
Hinge axis was found and introduced to dentistry by McCollum in 1929. Gnathology made fast progress with the invention and improvement of an articulator and the analysis of mandibular movement, in addition to the hinge axis. Gnathological treatment must be performed accurately step by step. A great deal of knowledge, experience and ability are necessary for each of the steps. But, first of all, it is important to know what exactly the hinge axis is and how important it is. The hinge axis must be taken correctly, and be always located identically. This technic is most important for gnatholgy. Besides, each of the steps being correctly studied and mastered, any error occuring during any step must be always corrected. It is the remount technic to correct the error. It will be easier to treat by taking the remount technic. If the remount technic is performed easily, correctly and skillfully, complicated gnathology will reduced to only a little. It is not gnathology to restore all teeth. Though, as there are so many teeth to be restored nowadays, the remount technic should be treated as a method of checking the steps. Thus, gnathology will be easier.
In the complete denture prosthodontics, occlusal types of the artificial teeth arrangement are generally held to exert a large influence on the retention, stability and support of the prothesis, and there is a fairly abundant published literature dealing with occlusal balance of the complete denture to date. From a current point of view, an occlusal type of complete denture at a-centric occlusal position always necessitates bilateral occlusal contacts. At an eccentric occlusal position, however, there is disagreement amongs investigators, some believe there is bilateral balanced occlusion, and some don't. Since D'Amico and Stallard reported that the posterior teeth always are separated by the anterior teeth in function on the natural dentition, Stuart, Elkins and Kato advocated a Gnathological denture. This type of occlusion is called Mutually Protected Occlusion. However, there is the difference of the supporting structure between the artificial teeth and the natural dentition, the former is supported by oral soft tissues and the latter is supported by the periodontal membrane and alveolie. For this reason, it is said that the balanced occlusion on the complete denture has advantages for the denture wearers. The purpose of this investigation was to compare with the difference in the occlusion between the bilateral balanced occlusion and the disclusion utilizing the electromyographic technique. One patient had maxillary and mandibular complete dentures, and other had a maxillary complete denture and mandibular metal splint. Full adjustable articulators (T.M.J, Hanau University 130-21) were used to make those prosthesis. The results showed as follows: 1) The patient wearing both maxillary and mandibular dentures, showed a smaller amount of muscle activity at the bilateral masseters and tempolal muscles with the bilateral balanced occlusion than with the disclusion in function. 2) The patient having mandibular matural dentition, showed less muscle activity and it tended to be less with the disclusion than the bilateral balanced occlusion, especially the difference of the muscle activity per stroke was smaller. The above results indicate that the changes of occlusal types cause lesser influence upon the masticatory movement with the patient who wearing only maxillary denture than with the patient wearing both maxillary and mandibular dentures.