Gnathologic Lloyd L. Cottingham, San Diego, Calv.
orthodontics D.D.S.
Gnathology is the science that treats of the biologics of the masticatory mechanism; that is the morphology, anatomy, histology, physiology, pathology and the therapeutics qf the oral organ, especially the jaws and teeth and the vital relations of this organ to the rest of the body.
-Harvey Stallard*
I
f we change the name in the definition from gnathology to orthodontics, we would find it synonymous. Isn’t orthodontics a science that treats of the biologics of the masticatory mechanism? We could also interpose periodontics, prosthodontics, or oral surgery with its recent developments; these specialties also are sciences that treat the biologics of the masticatory mechanisms. The authors of gnathology were purposely broad in their definition so as to be overinclusive of the disciplines of dentistry. They wanted gnathology to be more than the filling of holes, the removal of defective teeth, or the mere making of false plates. To them, gnathology was to be the complete care of the oral organ-an organ as vital as the organs of sight, smell, digestion, or any of the other organs receiving medical care. Gnathology is a science that embraces all of the systems of the mouth. It is the study of the morphology of each tooth-each tooth as a single entity, and each tooth as a member unit of the mouth. It includes the study of the investing tissues anchoring the teeth to their underlying structures. It continues to include the union of the underlying structures, their motivating musculature with their radial neural feedbacks and the binding sinews attaching the separate bony configurations of the jaw joint. Orthodontic
approach to gnathology
The orthodontic approach to gnathology is the science of moving teeth to a place where they will reside in a healthy culture that respects and conforms to all of the disciplines of the gnathic system. In brief, the gnathologic approach to orthodontics aims to put each tooth in a position where it will coordinate with the articulation of the mandible, where it will be in line with the forces of the musculature, and where it will be tranquil in its investing anchor tissues. This approach requires mounting the plaster casts of the teeth upon an articulator that will accept and duplicate the diagnostic jaw relations, so that the intermaxillary positions of the teeth are as they are in the patient’s face and cranium. The mandibular joints are important cranial parts. Their union must be included when casts are to be mounted on the articulator. For this reason, the mandibular posterior terminal hinge axis position and Presented Portland, 454
at the February, Ore.
1966,
annual
meeting
of the Pacific
0002~9416/78/100454+03$00.30/O
Coast
Society
0
of Orthodontists
in
1978 The C. V. Mosby Co.
Volume 74 Number 4
Gnnthologic
orthodontics
455
rotation must be located and recorded first. Then, the mandibular closure must be determined when the mandible is at this position. It is the starting post. It is the first base. It is the only reproducible position from which the mandible can be moved to its other positions. Orthognathic
diagnosis
A diagnosis based upon gnathologically articulated models is an aid to put alongside other orthodontic diagnostic records. It will show where the teeth are in the face and how they are related in the cranium. It will show how the teeth come together when the mandible rotates at its hinge axis closure. The first concern of gnathology is: “How does the centric occlusion of the closed teeth fit the rearmost closure of the jaw ?” That is what orthodontists have long been trying to do with casts mounted in their hands, and by looking at the closure in the mouth, and by means of headplates. Gnathology has a three-dimensional cephalometric instrument to measure discrepancies. In many dentitions mounted upon an articulator, a few pairs of opposing teeth will make occlusal contacts before any of the others. They contact first. For this reason, they have been called prematurities. As a patient crunches his teeth further together, the jaw is deflected forward or to the side. For this reason, we say that the teeth causing the jaw to deflect are the deflectors of the jaw closure. They cause a “deflective malocclusion.” All of us have seen a lingually inclined maxillary central incisor cause a patient to bite furthe; forward in order to shut his teeth. This is a gross observation of a deflective malocclusion. The orthodontist using gnathologically mounted casts can see how the mandible would close if such a deflector tooth were not present. This is a gross description of what he can detect in all cases. He can see, in any case, the teeth and the individual cusps that are the deflectors. He can see whether an incisor, a canine, a premolar, or a molar is deflecting the mandible. He may see what would appear as a Class III relationship change to a Class I or even to a Class II condition. An accepted Class I occlusion, from a casual observation, may change into a traumatic Class II malocclusion. What appears to be a unilateral cross-bite will often change to a bilateral distal occlusion, because of a lateral jumped bite. Most patients will show a deflection that hides the severity of distoclusion. With a gnathologic diagnosis, the orthodontist can see and measure the total amount of malocclusion. He can see and measure how far he must move each tooth. He can then engineer his mechanical therapy so as to move each tooth into a healthy periodontal medium allied with all the other supporting structures, including the mandibular joint. Posttreatment Following mechanical therapy, a new set of casts can be mounted on an articulator. These mounted models can be used first as an after-treatment diagnosis to see how well the prescription was followed. Then, they can be used in a setup for the fabrication of a clear thermoplastic positioner.’ which will compliment active treatment by moving teeth to perfection. Such a positioner will promote better coordination of teeth with the mandibular articulations, with the muscles of mastication, with the periodontium, and with the facial tissues. An orthodontist fortified with this diagnostic information can better engineer his
Am. J. Orrlwd. October 1978
technical procedures so that the positioner will be an adjunct to active treatment. The treatment time can be shortened, and the retention care problems will be minimized. The accomplished perfected results will enhance the patient’s chewing as well as the cosmetic appearance of his teeth and face. REFERENCES I. McCollum, B. B., and Stallard, H.: Considering the mouth as a functioning diagnosis: a research report, South Pasadena, Calif., 1955, Scientific Press. 2. Cottingham, Lloyd L.: Gnathologic clear plastic positioner, AM. J. ORTHOD. 2665
Fourth
Ave.
(92103)
unit as the basis of a dental 55: 23-31,
1969.
orthodontics D.D.S.
Gnathology is the science that treats of the biologics of the masticatory mechanism; that is the morphology, anatomy, histology, physiology, pathology and the therapeutics qf the oral organ, especially the jaws and teeth and the vital relations of this organ to the rest of the body.
-Harvey Stallard*
I
f we change the name in the definition from gnathology to orthodontics, we would find it synonymous. Isn’t orthodontics a science that treats of the biologics of the masticatory mechanism? We could also interpose periodontics, prosthodontics, or oral surgery with its recent developments; these specialties also are sciences that treat the biologics of the masticatory mechanisms. The authors of gnathology were purposely broad in their definition so as to be overinclusive of the disciplines of dentistry. They wanted gnathology to be more than the filling of holes, the removal of defective teeth, or the mere making of false plates. To them, gnathology was to be the complete care of the oral organ-an organ as vital as the organs of sight, smell, digestion, or any of the other organs receiving medical care. Gnathology is a science that embraces all of the systems of the mouth. It is the study of the morphology of each tooth-each tooth as a single entity, and each tooth as a member unit of the mouth. It includes the study of the investing tissues anchoring the teeth to their underlying structures. It continues to include the union of the underlying structures, their motivating musculature with their radial neural feedbacks and the binding sinews attaching the separate bony configurations of the jaw joint. Orthodontic
approach to gnathology
The orthodontic approach to gnathology is the science of moving teeth to a place where they will reside in a healthy culture that respects and conforms to all of the disciplines of the gnathic system. In brief, the gnathologic approach to orthodontics aims to put each tooth in a position where it will coordinate with the articulation of the mandible, where it will be in line with the forces of the musculature, and where it will be tranquil in its investing anchor tissues. This approach requires mounting the plaster casts of the teeth upon an articulator that will accept and duplicate the diagnostic jaw relations, so that the intermaxillary positions of the teeth are as they are in the patient’s face and cranium. The mandibular joints are important cranial parts. Their union must be included when casts are to be mounted on the articulator. For this reason, the mandibular posterior terminal hinge axis position and Presented Portland, 454
at the February, Ore.
1966,
annual
meeting
of the Pacific
0002~9416/78/100454+03$00.30/O
Coast
Society
0
of Orthodontists
in
1978 The C. V. Mosby Co.
Volume 74 Number 4
Gnnthologic
orthodontics
455
rotation must be located and recorded first. Then, the mandibular closure must be determined when the mandible is at this position. It is the starting post. It is the first base. It is the only reproducible position from which the mandible can be moved to its other positions. Orthognathic
diagnosis
A diagnosis based upon gnathologically articulated models is an aid to put alongside other orthodontic diagnostic records. It will show where the teeth are in the face and how they are related in the cranium. It will show how the teeth come together when the mandible rotates at its hinge axis closure. The first concern of gnathology is: “How does the centric occlusion of the closed teeth fit the rearmost closure of the jaw ?” That is what orthodontists have long been trying to do with casts mounted in their hands, and by looking at the closure in the mouth, and by means of headplates. Gnathology has a three-dimensional cephalometric instrument to measure discrepancies. In many dentitions mounted upon an articulator, a few pairs of opposing teeth will make occlusal contacts before any of the others. They contact first. For this reason, they have been called prematurities. As a patient crunches his teeth further together, the jaw is deflected forward or to the side. For this reason, we say that the teeth causing the jaw to deflect are the deflectors of the jaw closure. They cause a “deflective malocclusion.” All of us have seen a lingually inclined maxillary central incisor cause a patient to bite furthe; forward in order to shut his teeth. This is a gross observation of a deflective malocclusion. The orthodontist using gnathologically mounted casts can see how the mandible would close if such a deflector tooth were not present. This is a gross description of what he can detect in all cases. He can see, in any case, the teeth and the individual cusps that are the deflectors. He can see whether an incisor, a canine, a premolar, or a molar is deflecting the mandible. He may see what would appear as a Class III relationship change to a Class I or even to a Class II condition. An accepted Class I occlusion, from a casual observation, may change into a traumatic Class II malocclusion. What appears to be a unilateral cross-bite will often change to a bilateral distal occlusion, because of a lateral jumped bite. Most patients will show a deflection that hides the severity of distoclusion. With a gnathologic diagnosis, the orthodontist can see and measure the total amount of malocclusion. He can see and measure how far he must move each tooth. He can then engineer his mechanical therapy so as to move each tooth into a healthy periodontal medium allied with all the other supporting structures, including the mandibular joint. Posttreatment Following mechanical therapy, a new set of casts can be mounted on an articulator. These mounted models can be used first as an after-treatment diagnosis to see how well the prescription was followed. Then, they can be used in a setup for the fabrication of a clear thermoplastic positioner.’ which will compliment active treatment by moving teeth to perfection. Such a positioner will promote better coordination of teeth with the mandibular articulations, with the muscles of mastication, with the periodontium, and with the facial tissues. An orthodontist fortified with this diagnostic information can better engineer his
Am. J. Orrlwd. October 1978
technical procedures so that the positioner will be an adjunct to active treatment. The treatment time can be shortened, and the retention care problems will be minimized. The accomplished perfected results will enhance the patient’s chewing as well as the cosmetic appearance of his teeth and face. REFERENCES I. McCollum, B. B., and Stallard, H.: Considering the mouth as a functioning diagnosis: a research report, South Pasadena, Calif., 1955, Scientific Press. 2. Cottingham, Lloyd L.: Gnathologic clear plastic positioner, AM. J. ORTHOD. 2665
Fourth
Ave.
(92103)
unit as the basis of a dental 55: 23-31,
1969.
