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Sensory perception in overdenture patients
Sensory William
perception D. Kay,
D.D.S.,*
in overdenture and
Marshall
patients
5. Aber,
D.M.D.**
Emory University School of Dentistry, Atlanta, Ga.
T
he transition from natural teeth to suddenly becoming edentulous and wearing dentures is often a traumatic physical and psychologic experience for the patient. Frequently, weeks pass before the patient with new dentures can accept them as an integral part of his natural appearance and function. Many times, the patient believes t.hat he has lost his youth, his previous phonetic ability, and his senses of taste, smell, and tactile discrimination. Covering the hard palate and other tissues blocks vast regions of nerve receptors that respond to pain, pressure, and thermal changes. Although these receptors do not become completely afunctional, the rigidity and the insulating effect of the acrylic resin, porcelain, and metal materially alter their function. Although it is impossible to eliminate all adverse neurologic effects, the use of tooth-supported complete dentures, commonly called overdentures, makes possible a high degree of tactile discrimination. The most commonly used procedure for overdentures requires periodontal therapy for the remaining teeth, possible endodontic therapy, reduction of clinical crowns, and placement of gold copings or functional attachments. The prosthesis is constructed so that the retained teeth lend support, stability, and, in some instances, retention to the denture. Zamikoff’ has defined the overdenture as a complete denture supported by soft tissue and a few remaining natural teeth that have been altered to permit the denture to fit over them. In addition to the readily apparent advantages of added support, stability, retention, and preservation of bone, the ability of the overdenture to improve tactile sensory perception has received increased attention.?-4 Whereas many studies have been made of the mechanical advantages of the overdenture, a detailed study of the mechanisms of the nervous system in relation to overdentures has been largely ignored. This article examines some suggested neurologic mechanisms controlling cyclic jaw movements and the role of periodontal ligament nerve receptors in overdenture patients. The views expressed of the United States Air *Lieutenant Colonel, Institute of Technology. **Assistant
Professor,
herein are those of the authors and do not necessarily Force or the Department of Defense. USAF Department
(DC)
; Resident of Removable
in
Removable
Prosthodontics,
reflect
the views Air
Force
Prosthodontics.
615
616
Kay
REVIEW
and Abes OF THE LITERATURE
A study by Manly and co-workers5 compared the perception of oral sensationby natural teeth with that by dentures of the stimuli of thickness, light touch, hardness, and textures. They found no statistically significant difference in judgment concerning the thickness of Lucite disks and concluded that proprioceptive ability might depend upon the temporomandibular joint and the musclesof mastication. Using von Frey’s hairs to determine the tactile sensitivity of teeth, they reported that dentulous subjects responded 10 times more often than edentulous subjects. They attributed this result to the distribution of small forces through the denture base and the presence of supporting structures around the teeth in the dentulous patient. Kawamura and Watanabe” conducted a more refined version of the study of Manly and co-workers5 using wires of small incremental differences. The threshold for discrimination was 100 per cent higher in the edentulous subjects than in dentulous subjects. The dentulous group perceived differences in size of 0.2 to 0.3 mm. Kawamura and Watanabe6 concluded that the existence of the periodontal ligament also influenced proprioceptive discrimination, SiirilH and Laine’ found that 75 per cent of dentulous test subjects perceived metal foil 60 p thick, even after the mandibular teeth were anesthetized by mandibular nerve block. Later, they investigated the relationship between periodontal sensory perception and both oral proprioception and oral motor ability.8 When foil test pieces were placed between anterior and posterior teeth before and after anesthetizing, the supporting structures around the teeth served in perception of the thickness of these objects. The investigations of Brill and co-workerP, lo supported the concept that nerve receptors of the oral mucous membrane are related to the functional behavior of the musclesof the cheeks, lips, and tongue. They found that the control of dentures by muscle activity was reduced after the application of a surface anesthetic to the mucous membranesof the mouth. Nissen and associates,11investigating animal behavior, concluded that motor performance was related to sensoryfeedback. MihacP investigated the effect on identification of form by covering the hard palate with wax. He reported no significant difference in oral discrimination of the forms of the covered and uncovered palates. Berry and Mahood I3 tested 12 successfuldenture wearers and 12 patients who were unsuccessfulin wearing complete dentures. The successfulgroup scored low in oral sensoryperception and high in oral manipulative ability. However, the number of patients selected in each group was limited, and the criteria for the successful and unsuccessfulgroups were not precisely defined. They reported that patients with a low level of oral sensoryperception and good oral manipulative ability mastered control of their dentures with a high tolerance for or relative unawarenessof minor discrepancies in them. It followed that patients with a high level of oral sensory perception would be intolerant of errors in the prosthesisand unable to cope with the problem. The investigators mentioned that correction of these errors might lead to competence in wearing dentures. Litvak and associates” reported similar findings using stereognostictest forms.
;;“lL$n& ”
“Gj
Sensory perception
in overdenture
patients
617
Other investigators gave less credit to the role of the periodontal ligament in joint proprioception. Storey15 stated that the receptors of the temporomandibular mediated perception of the mandibular position and discrimination of the size of objects held between the teeth. Reduced vertical dimension of occlusion and severe malocclusion might impair sensory function of this joint, He referred to the investigations of Thilanderl” on muscle and joint receptors to support this idea. Thilande? showed that an arbitrary mandibular position between the rest position and the maximum opening could be duplicated by subjects. Use of a local anesthetic disrupted sensation in one or both joints, and subjects found it difficult to assume the original position. The changes were statistically significant; however, there was no statistically signficant difference when one or both joints were anesthetized. This finding suggested that the two temporomandibular joints might respond as a single unit, i.e., sensory changes in one joint might produce the same disruptive effect on proprioception as observed after anesthetizing both joints. Hannam, Matthews, and Yemml’ found that a local anesthetic applied to the tooth area did not abolish the inhibition of the masseter muscle that followed mechanical stimulation of a tooth. This observation indicated involvement of receptors other than those in the periodontal ligament. These investigators showed that vibration transmitted through the bone produced similar excitation of the muscle spindle. They believed that periodontal receptors were not involved in reflex systems to maintain cyclic jaw movements, although it was probable that information from them was used on a higher level in the over-all control of mastication.
DISCUSSION A sampling of the literature indicates that although proprioception of the mandible may be partly a function of receptors of the temporomandibular joint and the muscles of mastication, the periodontal ligaments of the remaining teeth also may have a tactile function. It may be assumed that any force or pressure on a rigid overdenture is transmitted to the underlying teeth and their periodontal ligaments. In addition, these periodontal receptors may provide greater tactile sense than is possible in the edentulous patient who relies, in part, on the soft tissues, muscles, and temporomandibular joint mechanisms to halt jaw closure. The research by Jergel* on the neurophysiology of the oral mechanism presents a hypothesis about cyclic jaw movement and its relationship to the teeth. His experiments with cats indicate that the fundamental mechanism underlying cyclic jaw movement appears to be the interaction of closing muscle proprioceptors of the jaw and the intraoral pressure receptors of the teeth and soft tissue. In dentulous patients, many dentists consider the receptors of the periodontal ligament important in the jaw opening reflex. It is presumed that edentulous patients rely on soft-tissue nerve receptors for the continuation of cyclic jaw movement. Some of the soft-tissue receptors, which range from free nerve endings to heat- and pressuresensitive types, are in the oral mucosa that is normally covered by the denture base. The broad dispersion of force by the base and its settling effect before achieving adequate resistance for masticatory function appear to hamper the denture patient in initiating a stimulus for the opening reflex. Allgoodl” states that at least two, and probably three, functionally different periodontal ligament receptors exist. They are
618
Kay and Ah
J. P,osthet. Dent. June, 1976
the pressoreceptorswith connections ascending to consciousness;the pressoreceptors that do not contribute information reaching consciousness,but provide information to the muscles; and the pain receptors. He states that the second group constitutes the overload protection and the masticatory stroke-termination mechanism. Jergezo has pointed out that reciprocal innervation generally is not seen in the jaw mechanism for the following reasons: ( 1) The relatively rigid inflexible structures present, such as teeth, limit the closing movement; (2) there are no muscle spindles in the digastric muscles; (3) the jaw opening reflex is prominent; and (4) the monosynaptic reflex of closure by natural dentition precludes the need for muscle spindles (stretch receptors) in the digastric muscles.Perhaps reciprocal innervation is useful only in the edentulous patient in whom mandibular closure can continue past the normal occlusal posture and result in stretching of the digastric muscles. Of interest also is the lack of stretch receptors in the lateral pterygoid muscles, which are among the most unique muscles of the body in view of their limitation for stretching. It is logical to infer that there is no need for spindle receptors. SUMMARY
The discussionof overdentures has been confined to their capacity to use abutment teeth to improve neuromuscular control of mandibular movement. Use of overdentures has been favored often because of their mechanical advantages, but seldom because of the sensory role of the retained abutment teeth. Even though the retained teeth may be periodontally diseased, they still may provide sufficient support for the transmissionof masticatory pressuresand sufficient periodontal ligament receptors to initiate a jaw opening reflex. Whereas conflicting evidence shows that the periodontal nerve receptors play a role in mandibular positional sensibility (proprioception) , pressureperception by the periodontal ligament remains a primary stimulus for the jaw opening reflex. Additional investigations will be essentialto a complete understanding of the role of the periodontal ligament receptors. However, recognition of the importance of the periodontal ligament receptors to the overdenture patient as a source of sensory input is vital. References 1. 2.
Zamikoff, I. I.: Overdentures, J. Am. Dent. Assoc. 86: 853-857, 1973. Loiselle, R. J., Crum, R. J., Rooney, G. E., and Stuever, C. H.: The Physiologic Basis for the Overlay Denture, J. PROSTHET. DENT. 28: 4-12, 1972. 3. Crum, R. J., and Loiselle, R. J.: Oral Perception and Proprioception: A Review of the Literature and Its Significance to Prosthodontics, J. PROSTHET. DENT. 28: 215-230, 1972. 4. Dodge, C. A.: Prevention of Complete Denture Problems by Use of Overdentures, J. PROSTHET. DENT. 30: 403-411, 1973. 5. Manly, R. S., Pfaffman, C., Lathrop, D. P., and Keyser, J.: Oral Sensory Thresholds of Persons With Natural and Artificial Dentitions, J. Dent. Res. 31: 305-312, 1952. 6. Kawamura, Y., and Watanabe, M.: Studies in Oral Sensory Thresholds, Med. J. Osaka Univ. 10: 291-301, 1960. 7. SiiriIB, H. S., and Laine, P.: The Tactile Sensibility of the Parodontium to Slight Axial Loadings of the Teeth, Acta Odontol. Stand. 21: 415-429, 1963.
Volume Numher
8. 9. 10. Il.
.12. 13. 14. 15. 16. 17. 18. 19. 20.
3j 6
Sensory
perception
in ouerdenture
patients
619
SiirilP, H. S., and Laine, P.: The Relation of Parodontal Sensory Appreciation to Oral Stereognosis and Oral Motor Ability, Suom. Hammaslaak. Toim. 63: 206-211, 1967. Brill, N.: Reflexes, Registrations, and Prosthetic Therapy, J. PROSTHET. DENT. ‘7: 341-360, 1957. Brill, N., Tryde, G., and Schubeler, S.: The Role of Exteroceptors in Denture Retention, J. PROSTHET. DENT. 9: 761-768, 1959. Nissen, H., Chow, K., and Semmer, J.: Effects of Restricted Opportunity for Tactile, Kinesthetic and Manipulative Experience on the Behavior of a Chimpanzee, Am. J. Psychol. 64: 485-507, 1951. Mihacs, B.: Effect of Covering the Palate on Identification of Forms in the Oral Cavity, Research project submitted for M.Ed. degree, The Pennsylvania State University, 1964. Berry, D., and Mahood, M.: Oral Stereognosis and Oral Ability in Relation to Prosthetic Treatment, Br. Dent. J. 120: 179-185, 1966. Litvak, H., Silverman, S., and Garfinkel, L.: Oral Stereognosis in Dentulous and Edentulous Subjects, J. PROSTHET. DENT. 25: 139-151, 1971. Storey, A.: Sensory Functions of the Temporomandibular Joint, J. Can. Dent. Assoc. 34: 294-300, 1968. Thilander, B.: Innervation of the Temporomandibular Joint Capsule in Man, Trans. R. Sch. Dent. Malmo, Series 2, No. 7, pp. 9-67, 1961. Hannam, A., Matthews, B., and Yemm, R.: Receptors Involved in the Response of the Masseter Muscle to Tooth Contact in Man, Arch. Oral Biol. 15: 17-24, 1970. Jerge, C.: The Neurologic Mechanism Underlying Cyclic Jaw Movements, J. PROSTHET. DENT. 14: 667680, 1964. Allgood, J.: Neuromuscular Control of Mandibular Movement, Dent. Stud. 52: 24-25, 1973. Jerge, C.: Comments on the Innervation of the Teeth, Dent. Clin. North Am., March, 1965, pp. 117-127. DR.
USAF MINOT
KAY
REGIONAL HOSPITAL ,4FB, N. D. 58705
Arms 4431 KELLOC CIRCLE DUNWOODY, GA. 30338 DR.
(SGD)
perception D. Kay,
D.D.S.,*
in overdenture and
Marshall
patients
5. Aber,
D.M.D.**
Emory University School of Dentistry, Atlanta, Ga.
T
he transition from natural teeth to suddenly becoming edentulous and wearing dentures is often a traumatic physical and psychologic experience for the patient. Frequently, weeks pass before the patient with new dentures can accept them as an integral part of his natural appearance and function. Many times, the patient believes t.hat he has lost his youth, his previous phonetic ability, and his senses of taste, smell, and tactile discrimination. Covering the hard palate and other tissues blocks vast regions of nerve receptors that respond to pain, pressure, and thermal changes. Although these receptors do not become completely afunctional, the rigidity and the insulating effect of the acrylic resin, porcelain, and metal materially alter their function. Although it is impossible to eliminate all adverse neurologic effects, the use of tooth-supported complete dentures, commonly called overdentures, makes possible a high degree of tactile discrimination. The most commonly used procedure for overdentures requires periodontal therapy for the remaining teeth, possible endodontic therapy, reduction of clinical crowns, and placement of gold copings or functional attachments. The prosthesis is constructed so that the retained teeth lend support, stability, and, in some instances, retention to the denture. Zamikoff’ has defined the overdenture as a complete denture supported by soft tissue and a few remaining natural teeth that have been altered to permit the denture to fit over them. In addition to the readily apparent advantages of added support, stability, retention, and preservation of bone, the ability of the overdenture to improve tactile sensory perception has received increased attention.?-4 Whereas many studies have been made of the mechanical advantages of the overdenture, a detailed study of the mechanisms of the nervous system in relation to overdentures has been largely ignored. This article examines some suggested neurologic mechanisms controlling cyclic jaw movements and the role of periodontal ligament nerve receptors in overdenture patients. The views expressed of the United States Air *Lieutenant Colonel, Institute of Technology. **Assistant
Professor,
herein are those of the authors and do not necessarily Force or the Department of Defense. USAF Department
(DC)
; Resident of Removable
in
Removable
Prosthodontics,
reflect
the views Air
Force
Prosthodontics.
615
616
Kay
REVIEW
and Abes OF THE LITERATURE
A study by Manly and co-workers5 compared the perception of oral sensationby natural teeth with that by dentures of the stimuli of thickness, light touch, hardness, and textures. They found no statistically significant difference in judgment concerning the thickness of Lucite disks and concluded that proprioceptive ability might depend upon the temporomandibular joint and the musclesof mastication. Using von Frey’s hairs to determine the tactile sensitivity of teeth, they reported that dentulous subjects responded 10 times more often than edentulous subjects. They attributed this result to the distribution of small forces through the denture base and the presence of supporting structures around the teeth in the dentulous patient. Kawamura and Watanabe” conducted a more refined version of the study of Manly and co-workers5 using wires of small incremental differences. The threshold for discrimination was 100 per cent higher in the edentulous subjects than in dentulous subjects. The dentulous group perceived differences in size of 0.2 to 0.3 mm. Kawamura and Watanabe6 concluded that the existence of the periodontal ligament also influenced proprioceptive discrimination, SiirilH and Laine’ found that 75 per cent of dentulous test subjects perceived metal foil 60 p thick, even after the mandibular teeth were anesthetized by mandibular nerve block. Later, they investigated the relationship between periodontal sensory perception and both oral proprioception and oral motor ability.8 When foil test pieces were placed between anterior and posterior teeth before and after anesthetizing, the supporting structures around the teeth served in perception of the thickness of these objects. The investigations of Brill and co-workerP, lo supported the concept that nerve receptors of the oral mucous membrane are related to the functional behavior of the musclesof the cheeks, lips, and tongue. They found that the control of dentures by muscle activity was reduced after the application of a surface anesthetic to the mucous membranesof the mouth. Nissen and associates,11investigating animal behavior, concluded that motor performance was related to sensoryfeedback. MihacP investigated the effect on identification of form by covering the hard palate with wax. He reported no significant difference in oral discrimination of the forms of the covered and uncovered palates. Berry and Mahood I3 tested 12 successfuldenture wearers and 12 patients who were unsuccessfulin wearing complete dentures. The successfulgroup scored low in oral sensoryperception and high in oral manipulative ability. However, the number of patients selected in each group was limited, and the criteria for the successful and unsuccessfulgroups were not precisely defined. They reported that patients with a low level of oral sensoryperception and good oral manipulative ability mastered control of their dentures with a high tolerance for or relative unawarenessof minor discrepancies in them. It followed that patients with a high level of oral sensory perception would be intolerant of errors in the prosthesisand unable to cope with the problem. The investigators mentioned that correction of these errors might lead to competence in wearing dentures. Litvak and associates” reported similar findings using stereognostictest forms.
;;“lL$n& ”
“Gj
Sensory perception
in overdenture
patients
617
Other investigators gave less credit to the role of the periodontal ligament in joint proprioception. Storey15 stated that the receptors of the temporomandibular mediated perception of the mandibular position and discrimination of the size of objects held between the teeth. Reduced vertical dimension of occlusion and severe malocclusion might impair sensory function of this joint, He referred to the investigations of Thilanderl” on muscle and joint receptors to support this idea. Thilande? showed that an arbitrary mandibular position between the rest position and the maximum opening could be duplicated by subjects. Use of a local anesthetic disrupted sensation in one or both joints, and subjects found it difficult to assume the original position. The changes were statistically significant; however, there was no statistically signficant difference when one or both joints were anesthetized. This finding suggested that the two temporomandibular joints might respond as a single unit, i.e., sensory changes in one joint might produce the same disruptive effect on proprioception as observed after anesthetizing both joints. Hannam, Matthews, and Yemml’ found that a local anesthetic applied to the tooth area did not abolish the inhibition of the masseter muscle that followed mechanical stimulation of a tooth. This observation indicated involvement of receptors other than those in the periodontal ligament. These investigators showed that vibration transmitted through the bone produced similar excitation of the muscle spindle. They believed that periodontal receptors were not involved in reflex systems to maintain cyclic jaw movements, although it was probable that information from them was used on a higher level in the over-all control of mastication.
DISCUSSION A sampling of the literature indicates that although proprioception of the mandible may be partly a function of receptors of the temporomandibular joint and the muscles of mastication, the periodontal ligaments of the remaining teeth also may have a tactile function. It may be assumed that any force or pressure on a rigid overdenture is transmitted to the underlying teeth and their periodontal ligaments. In addition, these periodontal receptors may provide greater tactile sense than is possible in the edentulous patient who relies, in part, on the soft tissues, muscles, and temporomandibular joint mechanisms to halt jaw closure. The research by Jergel* on the neurophysiology of the oral mechanism presents a hypothesis about cyclic jaw movement and its relationship to the teeth. His experiments with cats indicate that the fundamental mechanism underlying cyclic jaw movement appears to be the interaction of closing muscle proprioceptors of the jaw and the intraoral pressure receptors of the teeth and soft tissue. In dentulous patients, many dentists consider the receptors of the periodontal ligament important in the jaw opening reflex. It is presumed that edentulous patients rely on soft-tissue nerve receptors for the continuation of cyclic jaw movement. Some of the soft-tissue receptors, which range from free nerve endings to heat- and pressuresensitive types, are in the oral mucosa that is normally covered by the denture base. The broad dispersion of force by the base and its settling effect before achieving adequate resistance for masticatory function appear to hamper the denture patient in initiating a stimulus for the opening reflex. Allgoodl” states that at least two, and probably three, functionally different periodontal ligament receptors exist. They are
618
Kay and Ah
J. P,osthet. Dent. June, 1976
the pressoreceptorswith connections ascending to consciousness;the pressoreceptors that do not contribute information reaching consciousness,but provide information to the muscles; and the pain receptors. He states that the second group constitutes the overload protection and the masticatory stroke-termination mechanism. Jergezo has pointed out that reciprocal innervation generally is not seen in the jaw mechanism for the following reasons: ( 1) The relatively rigid inflexible structures present, such as teeth, limit the closing movement; (2) there are no muscle spindles in the digastric muscles; (3) the jaw opening reflex is prominent; and (4) the monosynaptic reflex of closure by natural dentition precludes the need for muscle spindles (stretch receptors) in the digastric muscles.Perhaps reciprocal innervation is useful only in the edentulous patient in whom mandibular closure can continue past the normal occlusal posture and result in stretching of the digastric muscles. Of interest also is the lack of stretch receptors in the lateral pterygoid muscles, which are among the most unique muscles of the body in view of their limitation for stretching. It is logical to infer that there is no need for spindle receptors. SUMMARY
The discussionof overdentures has been confined to their capacity to use abutment teeth to improve neuromuscular control of mandibular movement. Use of overdentures has been favored often because of their mechanical advantages, but seldom because of the sensory role of the retained abutment teeth. Even though the retained teeth may be periodontally diseased, they still may provide sufficient support for the transmissionof masticatory pressuresand sufficient periodontal ligament receptors to initiate a jaw opening reflex. Whereas conflicting evidence shows that the periodontal nerve receptors play a role in mandibular positional sensibility (proprioception) , pressureperception by the periodontal ligament remains a primary stimulus for the jaw opening reflex. Additional investigations will be essentialto a complete understanding of the role of the periodontal ligament receptors. However, recognition of the importance of the periodontal ligament receptors to the overdenture patient as a source of sensory input is vital. References 1. 2.
Zamikoff, I. I.: Overdentures, J. Am. Dent. Assoc. 86: 853-857, 1973. Loiselle, R. J., Crum, R. J., Rooney, G. E., and Stuever, C. H.: The Physiologic Basis for the Overlay Denture, J. PROSTHET. DENT. 28: 4-12, 1972. 3. Crum, R. J., and Loiselle, R. J.: Oral Perception and Proprioception: A Review of the Literature and Its Significance to Prosthodontics, J. PROSTHET. DENT. 28: 215-230, 1972. 4. Dodge, C. A.: Prevention of Complete Denture Problems by Use of Overdentures, J. PROSTHET. DENT. 30: 403-411, 1973. 5. Manly, R. S., Pfaffman, C., Lathrop, D. P., and Keyser, J.: Oral Sensory Thresholds of Persons With Natural and Artificial Dentitions, J. Dent. Res. 31: 305-312, 1952. 6. Kawamura, Y., and Watanabe, M.: Studies in Oral Sensory Thresholds, Med. J. Osaka Univ. 10: 291-301, 1960. 7. SiiriIB, H. S., and Laine, P.: The Tactile Sensibility of the Parodontium to Slight Axial Loadings of the Teeth, Acta Odontol. Stand. 21: 415-429, 1963.
Volume Numher
8. 9. 10. Il.
.12. 13. 14. 15. 16. 17. 18. 19. 20.
3j 6
Sensory
perception
in ouerdenture
patients
619
SiirilP, H. S., and Laine, P.: The Relation of Parodontal Sensory Appreciation to Oral Stereognosis and Oral Motor Ability, Suom. Hammaslaak. Toim. 63: 206-211, 1967. Brill, N.: Reflexes, Registrations, and Prosthetic Therapy, J. PROSTHET. DENT. ‘7: 341-360, 1957. Brill, N., Tryde, G., and Schubeler, S.: The Role of Exteroceptors in Denture Retention, J. PROSTHET. DENT. 9: 761-768, 1959. Nissen, H., Chow, K., and Semmer, J.: Effects of Restricted Opportunity for Tactile, Kinesthetic and Manipulative Experience on the Behavior of a Chimpanzee, Am. J. Psychol. 64: 485-507, 1951. Mihacs, B.: Effect of Covering the Palate on Identification of Forms in the Oral Cavity, Research project submitted for M.Ed. degree, The Pennsylvania State University, 1964. Berry, D., and Mahood, M.: Oral Stereognosis and Oral Ability in Relation to Prosthetic Treatment, Br. Dent. J. 120: 179-185, 1966. Litvak, H., Silverman, S., and Garfinkel, L.: Oral Stereognosis in Dentulous and Edentulous Subjects, J. PROSTHET. DENT. 25: 139-151, 1971. Storey, A.: Sensory Functions of the Temporomandibular Joint, J. Can. Dent. Assoc. 34: 294-300, 1968. Thilander, B.: Innervation of the Temporomandibular Joint Capsule in Man, Trans. R. Sch. Dent. Malmo, Series 2, No. 7, pp. 9-67, 1961. Hannam, A., Matthews, B., and Yemm, R.: Receptors Involved in the Response of the Masseter Muscle to Tooth Contact in Man, Arch. Oral Biol. 15: 17-24, 1970. Jerge, C.: The Neurologic Mechanism Underlying Cyclic Jaw Movements, J. PROSTHET. DENT. 14: 667680, 1964. Allgood, J.: Neuromuscular Control of Mandibular Movement, Dent. Stud. 52: 24-25, 1973. Jerge, C.: Comments on the Innervation of the Teeth, Dent. Clin. North Am., March, 1965, pp. 117-127. DR.
USAF MINOT
KAY
REGIONAL HOSPITAL ,4FB, N. D. 58705
Arms 4431 KELLOC CIRCLE DUNWOODY, GA. 30338 DR.
(SGD)