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More successful complete upper dentures
MORE: SUCCESSFUL COMPLETE UPPER DENTURES BERNARD A. SUSSMAN, D.D.S. New ‘York, N. Y. has always been considered one of the more successful products of prosthetic dentistry. New techniques for impression making have passed clinical analysis and received practical acceptance. Many advances have been made in obtaining the correct centric relation record. The procedure for insertion of a denture has been given the importance which it justly deserves. Unfortunately, in some instances, construction of a complete upper denture may be troublesome in spite of all the new techniques. Three factors which cause problems in complete upper denture construction will be discussed.
T consistently
HE COMPLETE
N,ATURAL
UPPER DENTURE
L.OWER TEETH
The construction of a complete upper denture to function against natural lower teeth is one of the more difficult tasks in prosthetic dentistry. The remaining natural lower teeth, because of use and abuse, may have different degrees of mobility. The line of occlusion is almost always like “hills and valleys.” If the teeth of an upper denture were to follow this line of occlusion of the lower natural teeth, any movement in function would unseat the upper denture. Therefore, the lower natural teeth should be ,shaped by grinding, as much, as is permissible according to roentgenographic examination, in order to make the line of occlusion more even. Then the upper teeth can occlude more correctly with and glide more easily over the lower teeth. When the limited grinding of the lower teeth does not produce the required change, however, one or more teeth of the upper denture must be eliminated so that a lower tooth whose occlusal height is higher than its neighbor’s cannot strike with an unequal, denture-unseating contact against an upper tooth. INCISAL
AND
CONDYLAR
GUIDANCE
When only six lower anterior teeth remain or when a free-end denture base removable partial denture has been worn for a long time, special care must be given to the incisal guidance and the condylar guidance in construction of the new complete upper denture. Necessity and habit have taught the patient how to move the mandible forward and upward so that he can chew more easily with the six lower anterior teeth. He has developed an improvised, but normal to him, edge-to-edge functional occlusion. The upper anterior teeth must be placed so that the lower anterior teeth have enough freedom to move in the new functional protrusive patterns. The upper 37
38
SUSSMIAN
J. Pros. Den. Jan.-Feb., 1960
anterior teeth,must not have any vertical overlap. If, because of esthetics, a horizontal overlap is necessary, there must be enough space between the upper and lower anterior teeth so that the lower teeth can move easily into the protrusive positions that are normal to the patient. Therefore, when a patient is wearing an old removable partial lower denture which has changed position, a new upper denture should be made only if a new removable partial lower denture is made at the same time. The occlusal height of the lower bikuspid teeth must be set at the same height as the adjacent cuspid teeth. In function, this prevents the displacement of the upper denture. INCORRECT
OCCLUSION
Failure of the complete upper denture to function properly results when the teeth of complete upper and lower dentures are ground into an incorrect occlusion. Many dentists have seen the logic and reasoning of grinding the occlusion into the reverse curve ; however, the usual success of complete upper denture construction was not always attained by this procedure. Analysis and study led to the conclusion that these failures were common if the teeth were ground into the reverse curve when the vault was flat, the residual ridges were short, and a Class II or Class III throat form was present. The teeth of complete dentures should be ground into the reverse curve of occlusion only when the maxillae are large, the palate has a high, rounded vault, the residual ridges have good length, and the soft palate slopes away from the hard palate at a slight angle (Class I throat form). SUMMARY
Three factors that make complete upper denture construction difficult have been discussed. If these factors are recognized and techniques established to compensate for them, complete upper denture construction will be more successful. 203 WEST NEW
YORK
74~~
ST.
23, N. Y.
T consistently
HE COMPLETE
N,ATURAL
UPPER DENTURE
L.OWER TEETH
The construction of a complete upper denture to function against natural lower teeth is one of the more difficult tasks in prosthetic dentistry. The remaining natural lower teeth, because of use and abuse, may have different degrees of mobility. The line of occlusion is almost always like “hills and valleys.” If the teeth of an upper denture were to follow this line of occlusion of the lower natural teeth, any movement in function would unseat the upper denture. Therefore, the lower natural teeth should be ,shaped by grinding, as much, as is permissible according to roentgenographic examination, in order to make the line of occlusion more even. Then the upper teeth can occlude more correctly with and glide more easily over the lower teeth. When the limited grinding of the lower teeth does not produce the required change, however, one or more teeth of the upper denture must be eliminated so that a lower tooth whose occlusal height is higher than its neighbor’s cannot strike with an unequal, denture-unseating contact against an upper tooth. INCISAL
AND
CONDYLAR
GUIDANCE
When only six lower anterior teeth remain or when a free-end denture base removable partial denture has been worn for a long time, special care must be given to the incisal guidance and the condylar guidance in construction of the new complete upper denture. Necessity and habit have taught the patient how to move the mandible forward and upward so that he can chew more easily with the six lower anterior teeth. He has developed an improvised, but normal to him, edge-to-edge functional occlusion. The upper anterior teeth must be placed so that the lower anterior teeth have enough freedom to move in the new functional protrusive patterns. The upper 37
38
SUSSMIAN
J. Pros. Den. Jan.-Feb., 1960
anterior teeth,must not have any vertical overlap. If, because of esthetics, a horizontal overlap is necessary, there must be enough space between the upper and lower anterior teeth so that the lower teeth can move easily into the protrusive positions that are normal to the patient. Therefore, when a patient is wearing an old removable partial lower denture which has changed position, a new upper denture should be made only if a new removable partial lower denture is made at the same time. The occlusal height of the lower bikuspid teeth must be set at the same height as the adjacent cuspid teeth. In function, this prevents the displacement of the upper denture. INCORRECT
OCCLUSION
Failure of the complete upper denture to function properly results when the teeth of complete upper and lower dentures are ground into an incorrect occlusion. Many dentists have seen the logic and reasoning of grinding the occlusion into the reverse curve ; however, the usual success of complete upper denture construction was not always attained by this procedure. Analysis and study led to the conclusion that these failures were common if the teeth were ground into the reverse curve when the vault was flat, the residual ridges were short, and a Class II or Class III throat form was present. The teeth of complete dentures should be ground into the reverse curve of occlusion only when the maxillae are large, the palate has a high, rounded vault, the residual ridges have good length, and the soft palate slopes away from the hard palate at a slight angle (Class I throat form). SUMMARY
Three factors that make complete upper denture construction difficult have been discussed. If these factors are recognized and techniques established to compensate for them, complete upper denture construction will be more successful. 203 WEST NEW
YORK
74~~
ST.
23, N. Y.