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Discussion of “soft tissue displacement beneath removable partial and complete dentures”
DISCUSSION REMOVABLE
OF “SOFT PARTIAL
TISSUE DISPLACEMENT BENEATH AND COMPLETE DENTURES”*
CARL 0. BOUCHER, D.D.S.** The Ohio State University, College
of
Dentistry,
Columbus, Ohio
I
CONGRATULATE Captain Lytle for his continuing efforts to add to our knowledge of the reaction of tissues to dentures. His essay constitutes a report of progress. He concludes, “Future scientific advancements in removable denture service must include a more complete knowledge and understanding of the physiologic condition of the soft tissues of the denture foundation.” This statement opens the door to active debate and further research, There can be little doubt about the fact of soft tissue displacement under dentures in the light of his measurements. Clinical evidence of the changes in soft tissues under dentures is readily available in the mouths of denture patients if one is willing to look for it and can recognize it. It is elemental (but nevertheless fundamental) that for every action there is a reaction. The very presence of denture bases on oral tissues which were designed by Nature to be exposed to oral fluids and to be stimulated by the action of the tongue, cheeks, lips, and food must produce changes in these oral tissues. It seems logical that such changes would be minimized if the tissues were allowed their normal environment for a part of each day. This can easily be arranged by having the patient leave the dentures out of the mouth each night. However, external pressures are applied to dentures and, through them, to these oral tissues. The evidence shown by Captain Lytle indicates that two factors are involved in determination of the amount of change. First, the younger the patient, the greater the change. This is to be expected, because the bone of young patients is more plastic than that of older ones, thus it is more responsive to pressure. Second, the smaller the supporting area (of the denture base), the greater the change in the tissues. This is easily observed clinically. The significance of these observations is obvious. Everything possible should be done to postpone the loss of natural teeth, and denture bases should be extended to the limits of the health and the function of the surrounding tissues. These recommendations have been recognized for many years, but unfortunately they have not been applied for all denture patients. Captain Lytle states, “. . . The soft tissues of the denture-supporting area may accommodate ill-fitting dentures ; because of their ability to make this accommoRead before the Academy of Denture Prosthetics in Minneapolis, *Lytle, Robert B.: J. PROS. DEN. 12:34-43, 1961. **Professor and Chairman, Division of Prosthodontfcs. 44
Minn.
DISCUSSION
45
dation, gross occlusal discrepancies may be concealed, and the retention and stability manifested may be at the expense of the health of the soft tissues.” This statement points out one of the most vulnerable spots in prosthodontics today. It is the fact that the adaptability of soft oral tissues can cover up some inaccuracies of impressions and denture bases as well as errors in occlusion, and this permits some patients to tolerate these inaccuracies and errors. The fact that the patients can tolerate the errors and inaccuracies is no excuse for their existence. The dentist knows they exist, and it is his responsibility to eliminate them. Many underextended denture bases, with the resultant bone loss, are seen. It is known that all available denture-base materials shrink and warp and that processing changes produce errors in occlusion. The question is, “What can be done about it ?” First, the dentist can insist on restoring the tissues to a healthy condition before he makes impressions. He can insist that the patient leave the denture out of the mouth until the tissues are healthy before impressions are made. No intelligent surgeon would operate on a patient without bringing him into as good condition as possible before surgical procedures are undertaken, except in a life or death emergency. Denture service is an elective, not emergency, service, and the patient can plan his time and activities so that the mouth will be healthy before the impressions are made. Second, it is time that dentists stop accepting the manufacturer’s word that the best possible denture-base materials are now available. Base materials do change in significant amounts even though the measurements are said to be small. If the tissues covered by dentures were hard, no dentures would fit. Why “condition” oral tissues and immediately place new dentures on them which uncondition the tissues as soon as they are inserted? Let us insist upon a search for better denture-base materials. Third, it is more or less common practice to let dentures “settle” into the tissues before occlusal adjustments are made on the teeth. This procedure is incorrect on two counts. Assuming that the tissues have been made healthy before the impressions are made, the adaptation of the bases to the tissues (as well as the health of the temporomandibular joints) will be optimal at the time the dentures are inserted. Interocclusal records made at this time will most accurately record the bone to bone relations of the mandible to the maxillae. Later, as Captain Lytle intimated, the dentures would have deformed the soft tissues in an attempt to eliminate the inaccuracy of the adaptation of the bases. If the corrections are made by means of new interocclusal records at the time of insertion, these soft tissues will not be required to adapt to an occlusion that may have been built on erroneous records made for the construction of the dentures, and they will not have to alter to accommodate to the processing changes. Dentures with acrylic resin bases change after they are inserted in the patient’s mouth. This results from the absorption of water by the resin. The change requires additional adjustment of the occlusion. The remounting records are saved, and \vhen new tlentures are replaced on the same plaster mountings on the same articulator 2 weeks or more after the dentures are inserted, the occlusion is found routinely not to be the same as it was on the day the dentures were inserted. Re-
46
BOUCHER
J. Pros. Jan.-Feb.,
Den. 1962
grinding the occlusion on these same mountings corrects soreness of which the patient may be complaining. In some instances, these changes in the denture bases are so great that the dentures will rock on the plaster mountings that have been poured into them. It is unrealistic to expect the soft tissues to continue to cover up the changes of denture-base materials. Captain Lytle has given an excellent short-term picture of the changes that occur under denture bases. Further research is needed to determine the nature and amount of the long range changes under dentures. 305 WEST COLUMBUS
TWELFTH AVE. 10, OHIO
OF “SOFT PARTIAL
TISSUE DISPLACEMENT BENEATH AND COMPLETE DENTURES”*
CARL 0. BOUCHER, D.D.S.** The Ohio State University, College
of
Dentistry,
Columbus, Ohio
I
CONGRATULATE Captain Lytle for his continuing efforts to add to our knowledge of the reaction of tissues to dentures. His essay constitutes a report of progress. He concludes, “Future scientific advancements in removable denture service must include a more complete knowledge and understanding of the physiologic condition of the soft tissues of the denture foundation.” This statement opens the door to active debate and further research, There can be little doubt about the fact of soft tissue displacement under dentures in the light of his measurements. Clinical evidence of the changes in soft tissues under dentures is readily available in the mouths of denture patients if one is willing to look for it and can recognize it. It is elemental (but nevertheless fundamental) that for every action there is a reaction. The very presence of denture bases on oral tissues which were designed by Nature to be exposed to oral fluids and to be stimulated by the action of the tongue, cheeks, lips, and food must produce changes in these oral tissues. It seems logical that such changes would be minimized if the tissues were allowed their normal environment for a part of each day. This can easily be arranged by having the patient leave the dentures out of the mouth each night. However, external pressures are applied to dentures and, through them, to these oral tissues. The evidence shown by Captain Lytle indicates that two factors are involved in determination of the amount of change. First, the younger the patient, the greater the change. This is to be expected, because the bone of young patients is more plastic than that of older ones, thus it is more responsive to pressure. Second, the smaller the supporting area (of the denture base), the greater the change in the tissues. This is easily observed clinically. The significance of these observations is obvious. Everything possible should be done to postpone the loss of natural teeth, and denture bases should be extended to the limits of the health and the function of the surrounding tissues. These recommendations have been recognized for many years, but unfortunately they have not been applied for all denture patients. Captain Lytle states, “. . . The soft tissues of the denture-supporting area may accommodate ill-fitting dentures ; because of their ability to make this accommoRead before the Academy of Denture Prosthetics in Minneapolis, *Lytle, Robert B.: J. PROS. DEN. 12:34-43, 1961. **Professor and Chairman, Division of Prosthodontfcs. 44
Minn.
DISCUSSION
45
dation, gross occlusal discrepancies may be concealed, and the retention and stability manifested may be at the expense of the health of the soft tissues.” This statement points out one of the most vulnerable spots in prosthodontics today. It is the fact that the adaptability of soft oral tissues can cover up some inaccuracies of impressions and denture bases as well as errors in occlusion, and this permits some patients to tolerate these inaccuracies and errors. The fact that the patients can tolerate the errors and inaccuracies is no excuse for their existence. The dentist knows they exist, and it is his responsibility to eliminate them. Many underextended denture bases, with the resultant bone loss, are seen. It is known that all available denture-base materials shrink and warp and that processing changes produce errors in occlusion. The question is, “What can be done about it ?” First, the dentist can insist on restoring the tissues to a healthy condition before he makes impressions. He can insist that the patient leave the denture out of the mouth until the tissues are healthy before impressions are made. No intelligent surgeon would operate on a patient without bringing him into as good condition as possible before surgical procedures are undertaken, except in a life or death emergency. Denture service is an elective, not emergency, service, and the patient can plan his time and activities so that the mouth will be healthy before the impressions are made. Second, it is time that dentists stop accepting the manufacturer’s word that the best possible denture-base materials are now available. Base materials do change in significant amounts even though the measurements are said to be small. If the tissues covered by dentures were hard, no dentures would fit. Why “condition” oral tissues and immediately place new dentures on them which uncondition the tissues as soon as they are inserted? Let us insist upon a search for better denture-base materials. Third, it is more or less common practice to let dentures “settle” into the tissues before occlusal adjustments are made on the teeth. This procedure is incorrect on two counts. Assuming that the tissues have been made healthy before the impressions are made, the adaptation of the bases to the tissues (as well as the health of the temporomandibular joints) will be optimal at the time the dentures are inserted. Interocclusal records made at this time will most accurately record the bone to bone relations of the mandible to the maxillae. Later, as Captain Lytle intimated, the dentures would have deformed the soft tissues in an attempt to eliminate the inaccuracy of the adaptation of the bases. If the corrections are made by means of new interocclusal records at the time of insertion, these soft tissues will not be required to adapt to an occlusion that may have been built on erroneous records made for the construction of the dentures, and they will not have to alter to accommodate to the processing changes. Dentures with acrylic resin bases change after they are inserted in the patient’s mouth. This results from the absorption of water by the resin. The change requires additional adjustment of the occlusion. The remounting records are saved, and \vhen new tlentures are replaced on the same plaster mountings on the same articulator 2 weeks or more after the dentures are inserted, the occlusion is found routinely not to be the same as it was on the day the dentures were inserted. Re-
46
BOUCHER
J. Pros. Jan.-Feb.,
Den. 1962
grinding the occlusion on these same mountings corrects soreness of which the patient may be complaining. In some instances, these changes in the denture bases are so great that the dentures will rock on the plaster mountings that have been poured into them. It is unrealistic to expect the soft tissues to continue to cover up the changes of denture-base materials. Captain Lytle has given an excellent short-term picture of the changes that occur under denture bases. Further research is needed to determine the nature and amount of the long range changes under dentures. 305 WEST COLUMBUS
TWELFTH AVE. 10, OHIO