To THE EDITOR:
In the article, “Edentulous Position of the Temporomandibular Joint” (March 1992;67:401-04), the authors state that the study purpose was to compare the condylar head-glenoid fossa relationship in edentulous patients with vertically and horizontally correct dentures and in the same patients with the dentures out and the ridges brought as close together as possible. They did accomplish their aim, but made assumptions and then drew several conclusions not tested or otherwise addressed in the study. These are: 1. The study assumes that the “edentulous position of the temporomandibular joint” (closed ridge-to ridge position) is truly physiologic and not an artificially strained position. This was not tested. 2. The study in no way shows that “this changed condylar position may be a pathologic one,” and further that it “is a pathologic position of the temporomandibular joint. . . ” 3. The study in no way “suggests that it is important to correctly determine the vertical dimension of occlusion and the intercuspal position. . . for the proper position of the condyle within the glenoid fossa to prevent temporomandibular joint disorders.” The authors present no references, evidence, or discussion to support the validity of the ridge-to-ridge position or to support any pathologic effects. I would appreciate knowing if any exists. JEREMY
SHULMAN,
213
OFFICE BUILDING VA 23502
JANAF
NORFOLK,
DDS
To THE EDITOR:
In response to Dr. Shulman’s comments regarding our article, “Edentulous position of the Temporomandibular Joint” (J PROSTHET DENT 1992;67:401-4), it is necessary to state that in our report, there is no word about the edentulous position of .the temporomandibular joint, which “is truly physiologic and not an artificially strained position.” We must stress that the primary purpose of our research is to obtain new knowledge about the temporomandibular joints and jaws in edentulous patients. We strive to learn as much as possible about masticatory function after total tooth loss and what changes occur with jaws and TMJs. When the maxillary and mandibular residual ridges approximate. We found that after loss of the support of all teeth, some known features of physiological position disappeared, such as the intercuspal position and the retruded contact position. When the maxillary and mandiblar residual ridges approximate, the condyle and mandible are in a special position that is different from the positions when natural teeth are in their proper position. Our results show that in this position, the upper and posterior joint spaces are reduced and the distance on the Y axis between the center of the glenoid fossae and the center of the condyle is shortened. To us it indicates that the condyle has moved upward and backward in the situation. We define pathology as a branch of medicine that deals
998
with the nature of disease, especially with the structural and functional changes caused by disease. It is not difficult to understand that loss of all the teeth is a pathological state. By edentulous position of the TMJs, we mean a position of condyle and mandible after loss of all the teeth and without complete dentures in place. When the maxillary and mandibular residual ridges approximate, although the patient can tolerate it, it is not a functional condition of mastication. We also find that the patient cannot maintain this position for a long time. When the natural teeth are in place, this position cannot occur, even though the mandible is “artificially strained.” If the condition of loss of all the teeth can be called a pathological state, we may think that the edentulous position of the TMJs is a pathological position. Since there has been very little study of the edentulous position of the TMJs it is necessary for us to investigate its significance and effect on masticatory function. Several studies have been made regarding the relationship between the change of occlusion, condyle position in glenoid fossa and vertical dimension, and temporomandibular joint disorders. l-3 Although there is controversy in the studies, the relationship between the changed condyle and TMJ disorders has been confirmed.4 The TMJ disorder could be treated by reconstruction of the occlusion and adjustment of condylar position in the glenoid fossa. Our study shows that in the edentulous patient the position of the condyle is in the most posterior position of glenoid fossa and the vertical dimension is decreased. We feel that it proves there is a close relationship between the vertical dimension and the position of the condyle. So it is essential to determine the correct vertical dimension and intercuspal position in the edentulous patient with complete dentures to adjust the condyle to a proper position within the glenoid fossa. Lru HONGCHEN,
MD,
PHD
POSTGRADUATE MEDICAL COLLEGE AND GENERAL HOSPITAL OF CHINESE PLA 28 FUXIN ROAD BEIJING, CHINA
REFERENCES Schopper AF. Loss of vertical dimension: causes and effects: diagnosis and various recommended treatments. J PROSTHET DENT 1959;9:428-31. Hansen CA, Axinn S. Incidence of mandibular dysfunction symptoms in individuals who remove their complete dentures during sleep. J PROSTHET DENT 1984;51:16-8. Wilding RX, Owen CP. The prevalence of temporomandibular joint dysfunction in edentulous no-denture wearing individuals. 3 Oral Rehabil 1987;14:175-82. Mongini F. Anatomic and clinical evaluation of the relationship between the temporomandibular joint and occlusion. J PROSTHET DENT 1977;38:539-51.
DECEMBER
1992
VOLUME
68
NUMBER
6
In the article, “Edentulous Position of the Temporomandibular Joint” (March 1992;67:401-04), the authors state that the study purpose was to compare the condylar head-glenoid fossa relationship in edentulous patients with vertically and horizontally correct dentures and in the same patients with the dentures out and the ridges brought as close together as possible. They did accomplish their aim, but made assumptions and then drew several conclusions not tested or otherwise addressed in the study. These are: 1. The study assumes that the “edentulous position of the temporomandibular joint” (closed ridge-to ridge position) is truly physiologic and not an artificially strained position. This was not tested. 2. The study in no way shows that “this changed condylar position may be a pathologic one,” and further that it “is a pathologic position of the temporomandibular joint. . . ” 3. The study in no way “suggests that it is important to correctly determine the vertical dimension of occlusion and the intercuspal position. . . for the proper position of the condyle within the glenoid fossa to prevent temporomandibular joint disorders.” The authors present no references, evidence, or discussion to support the validity of the ridge-to-ridge position or to support any pathologic effects. I would appreciate knowing if any exists. JEREMY
SHULMAN,
213
OFFICE BUILDING VA 23502
JANAF
NORFOLK,
DDS
To THE EDITOR:
In response to Dr. Shulman’s comments regarding our article, “Edentulous position of the Temporomandibular Joint” (J PROSTHET DENT 1992;67:401-4), it is necessary to state that in our report, there is no word about the edentulous position of .the temporomandibular joint, which “is truly physiologic and not an artificially strained position.” We must stress that the primary purpose of our research is to obtain new knowledge about the temporomandibular joints and jaws in edentulous patients. We strive to learn as much as possible about masticatory function after total tooth loss and what changes occur with jaws and TMJs. When the maxillary and mandibular residual ridges approximate. We found that after loss of the support of all teeth, some known features of physiological position disappeared, such as the intercuspal position and the retruded contact position. When the maxillary and mandiblar residual ridges approximate, the condyle and mandible are in a special position that is different from the positions when natural teeth are in their proper position. Our results show that in this position, the upper and posterior joint spaces are reduced and the distance on the Y axis between the center of the glenoid fossae and the center of the condyle is shortened. To us it indicates that the condyle has moved upward and backward in the situation. We define pathology as a branch of medicine that deals
998
with the nature of disease, especially with the structural and functional changes caused by disease. It is not difficult to understand that loss of all the teeth is a pathological state. By edentulous position of the TMJs, we mean a position of condyle and mandible after loss of all the teeth and without complete dentures in place. When the maxillary and mandibular residual ridges approximate, although the patient can tolerate it, it is not a functional condition of mastication. We also find that the patient cannot maintain this position for a long time. When the natural teeth are in place, this position cannot occur, even though the mandible is “artificially strained.” If the condition of loss of all the teeth can be called a pathological state, we may think that the edentulous position of the TMJs is a pathological position. Since there has been very little study of the edentulous position of the TMJs it is necessary for us to investigate its significance and effect on masticatory function. Several studies have been made regarding the relationship between the change of occlusion, condyle position in glenoid fossa and vertical dimension, and temporomandibular joint disorders. l-3 Although there is controversy in the studies, the relationship between the changed condyle and TMJ disorders has been confirmed.4 The TMJ disorder could be treated by reconstruction of the occlusion and adjustment of condylar position in the glenoid fossa. Our study shows that in the edentulous patient the position of the condyle is in the most posterior position of glenoid fossa and the vertical dimension is decreased. We feel that it proves there is a close relationship between the vertical dimension and the position of the condyle. So it is essential to determine the correct vertical dimension and intercuspal position in the edentulous patient with complete dentures to adjust the condyle to a proper position within the glenoid fossa. Lru HONGCHEN,
MD,
PHD
POSTGRADUATE MEDICAL COLLEGE AND GENERAL HOSPITAL OF CHINESE PLA 28 FUXIN ROAD BEIJING, CHINA
REFERENCES Schopper AF. Loss of vertical dimension: causes and effects: diagnosis and various recommended treatments. J PROSTHET DENT 1959;9:428-31. Hansen CA, Axinn S. Incidence of mandibular dysfunction symptoms in individuals who remove their complete dentures during sleep. J PROSTHET DENT 1984;51:16-8. Wilding RX, Owen CP. The prevalence of temporomandibular joint dysfunction in edentulous no-denture wearing individuals. 3 Oral Rehabil 1987;14:175-82. Mongini F. Anatomic and clinical evaluation of the relationship between the temporomandibular joint and occlusion. J PROSTHET DENT 1977;38:539-51.
DECEMBER
1992
VOLUME
68
NUMBER
6
