Orthodontic treatment in adults with temporomandibular dysfunction symptoms Bengt Ingervall, D.D.S., Odont.Dr.* Gijteborg,
Sweden
T
he most common methods for correction of occlusal disharmony in the adult dentition have been (1) selective grinding or (2) rehabilitation with fixed prostheses. Apart from these methods, textbooks describing the treatment of patients with functional disturbances of the masticatory system also mention orthodontic treatment as a means of eliminating occlusal interferences, stabilizing the occlusion, and creating favorable tooth contacts during gliding movements.lj 2 Occlusal disharmony is a purely functional concept and can occur in any morphologic malocclusion.3 Occlusal disharmony in certain types of malocclusion is difficult to correct by grinding or prosthetic methods but can relatively simply be treated orthodontically. This report is a description of typical cases in which orthodontic treatment was chosen. All of the patients were referred for orthodontic treatment from a department of stomatognathic physiology because the conventional methods of treatment used in that department (grinding and prosthetics) were less suitable in these cases. The aim of all methods of treatment is to correct the occlusion in order to abolish mandibular dysfunction and prevent its recurrence. During the acute phase of mandibular dysfunction symptoms, treatment methods such as splints, exercises, and heat treatment are often used regardless of the type of occlusal disharmony and possible morphologic malocclusion. Anterior cross-bite Most patients receiving orthodontic treatment of symptom-provoking occlusal disharmony have anterior cross-bite. Orthodontic treatment is preferred because (1) elimination by grinding of occlusal interferences of front teeth may be undesirable for esthetic reasons and (2) it may be impossible to achieve occlusal stability after grinding. That is, after the interfering tooth substance is ground away there is no occlusal stop (Fig. 1). The tooth may then elongate and a new interference will be created. Case 1 (Fig. 2). A 37-year-old woman had been referred to the department of stomatognathic physiology by her general dentist becauseof a 2 year history of intermittent right-sided facial pain. Clinical examination revealed tenderness to palpation of the right temporal muscle, the lateral pterygoid muscles, and the neck musclesbilaterally. There was also clicking in both temporomandibular joints. The upper right central incisor was in cross-bite, interfering
in the retruded mandibu-
*Department of Orthodontics, Faculty of Odontology, University of GSteborg OOiX-9416/78/0573-0551$00.90/O
0
The C. V. Mosby Co.
551
552
lngervnll
POSSibh el
a
b
Flg. 1. a, Anterior cross-bite before grinding. b, After grinding. It is rarely self-corrective. Elongation is more likely to occur.
lar position. The mandible was displacedanteriorly so that the anteroposterior distance between the retruded and intercuspal positions was 2 mm. Orthodontic treatment consistedof sagittal expansion of the upper dental arch with a labial arch wire, thus creating space for the crowded central incisor to move labially. Six months of this treatment corrected the malocclusion and abolished the patient’s pain and dysfunction symptoms. Despite the temporary use of a lower splint, the upper right central incisor became tender during the treatment and had to be relieved from some of the occlusal interference by incisal grinding. Case 2 (Fig. 3). A 35year-old woman complained of nocturnal bruxism and also clenching in the daytime in stress situations. In the mornings she experienced a feeling of fatigue in the temporomandibular joints and in the face. She had had a headacheevery day for the last 6 months. Numerous muscleswere tender on palpation-the temporal and lateral pterygoid musclesbilaterally, the right masseterand sternocleidomastoid muscles, and the left digastric muscle. The left temporomandibularjoint was also tender on palpation and there was clicking in both joints. The path of opening and closing movement as well as protrusion was irregular and the range of lateral and protrusive movements was somewhat limited. The patient had a skeletal mandibular asymmetry, causinga cross-biteof the upper left canine and first premolar. The canine interfered in the retruded position. This displaced the mandible to the left into the intercuspal position and tended to “lock” the occlusion. The upper lateral incisors were congenitally missing. The patient had been treated with a splint and movement exercises, which improved her condition but did not relieve the symptoms or solve her occlusal problems. Orthodontic treatment consisted of insertion of an upper labial arch wire, which opened up space for pontics replacing the lateral incisors and moved the upper left canine buccally. This treatment, lasting 9 months, eliminated the interference and the patient’s pain. After treatment, which concluded with the placement of two smah inlay bridges in the upper front, she had headache only about once a month. Case 3 (Fig. 4). A 4%year-old woman had had symptoms of functional disturbance of the masticatory system for more than 5 years. The symptoms were most pronounced in the mornings and consistedof dull aching in the left tempommandibular joint and in the masticatory muscles.She had periodic headacheand was aware of tooth clenching. There was locking of the mandible during movements and she was aware of bilateral temporomandibular joint clicking. The temporal and lateral pterygoid muscles bilaterally were tender on palpation, as were the right masseterand the left digastric muscles. The range of movement of the mandible was normal, but mandibular movements were painful.
Volume 73 Number 5
Orthodontic
treatment in adults with Th4J dysfunction
553
Flg. 2. Case 1, a and d, lntercuspal positions before treatment. b and c, Retruded contact positions before treatment. Upper right central incisor in cross-bite and interfering in the retruded position. e, 1, g, lntercuspal positions after treatment.
In the intercuspalposition the upper right canine and all incisorswere in cross-bite. The canine and the right lateral incisor interfered in the retruded position. The patient was treated at the department of stomatognathic physiology with a bite splint and short-wave heat therapy, but exerciseshad to be abandoned because of pain on movement. The splint, which was later replacedby bilateral cap splints in the lower jaw, stabilizedthe occlusion and reduced the patient’s symptoms but attempts to remove the splints caused recurrence of her headache. As permanent therapy, the anterior cross-bitewas eliminated by sagittal expansion of the upper dental arch with the aid of a labial arch wire combined with ClassIII elasticsto a lower labial arch. The occlusion was corrected in 5 months, resulting in complete disappearanceof the patient’s symptoms.
554
lngervall
Fig. 3. Case 2. cross-bite, upper canine interfering.
a and b, lntercuspal
positions before treatment. lateral incisors missing. c, Retruded contact d, e, f, lntercuspal positions after treatment.
Upper left canine and first premolar in position before treatment. Upper left g, Upper dental arch after treatment.
Arch width discrepsncies Another type of malocclusion in which orthodontic treatment can be of value is in cases of discrepancy between upper and lower arch widths. In such cases elimination of occlusal interferences by grinding may mean that large amounts of tooth substance have to be removed. Grinding also has to be done on practically all lateral teeth. This may be undesirable for psychological reasons, and it also involves the risk of reduced chewing
Volume 73 Number 5
Orthodontic
treatment in adults with TMJ dysfunction
555
Fig. 4. Case 3. a and b, lntercuspal positions, right and left sides, before treatment. All incisors and right canine in cross-bite. c and d, Before treatment, retruded contact positions. Upper right canine and lateral incisor interfering. e, f, g, lntercuspal positions after treatment.
efficiency because of flattened occlusal surfaces. A case of this type has been described previously3 and the following is another example. Case 4 (Fig. 5). A 17-year-old girl had had her symptoms for 3 months. They consisted of right-sided pain below and in front of the ear which was most severe in the mornings and was combined with difficulty in opening the mouth. The patient thought that she had a habit of clenching her teeth. Clinical examination revealed reduced mouth-opening capacity and that all mandibular movements were accompanied by pain in the right masseter region. The upper dental arch was narrow in relation to the lower, so that the intercuspidation was inadequate. There was a 1.5 mm.
556
.4m J Onhod
Ingervull
Fig. 5. Case
4. a and
b, lntercuspal
positions
before
treatment.
c and
d, lntercuspal
positions
after
treatment.
lateral shift of the midline between the intercuspal and retruded contact positions. Treatment was started with a splint and exercises. This reduced the pain on movement and brought about a slight increase in opening capacity. It was not possible to eliminate the cuspal interference through grinding because large amounts of tooth substance would have had to be ground away. Instead, the upper dental arch was widened transversely with an upper plate equipped with an expansion screw in the midline. The widening, which took 5 months, eliminated the lateral shift between the retruded and intercuspal positions and resulted in acceptable intercuspidation. This result still remained stable 1 year after cessation of retention, which lasted 6 months. All the patient’s dysfunction symptoms disappeared during the active expansion.
Buccal cross-bite (“scissors bite”) Posterior teeth in buccal cross-bite may cause serious cuspal interference during gliding movements. Attempts to abolish this interference by grinding often mean extensive grinding. Another limitation of this approach is that no occlusal stop is present after the grinding, with consequent risk of elongation and recurrence of the interference. In these cases, elimination of the interference by tooth movement is preferable. Case 5 (Fig. 6). A 19-year-old girl had only mild subjective symptoms, but she was unable to find a distinct intercuspal position, which she regarded as a problem. She was aware of nocturnal grinding and clenching in the daytime. Clinically, slight tenderness on palpation was found in the right temporal and lateral pterygoid muscles as well as on palpation of the right temporomandibular joint. She also had slight pain on both sides of the face during mandibular movements. The occlusion was postnormal and a space deficiency had displaced the lower left premolars lingually so that a buccal cross-bite relation was present between the upper and lower left premolars. The upper left premolars were tipped somewhat buccally. Muscle exercises eliminated the patient’s muscle tenderness and pain but she continued to complain of an indistinct intercuspal position. Orthodontic treatment consisted of sagittal expansion of the lower left dental arch with a labial arch wire. Simultaneously, an upper plate was fitted. This plate had a frontal plateau (bite plane) that temporarily disoccluded the posterior teeth. It also had a
Volume 73 Number 5
Fig. 6. Case 5. a, b, c, lntercuspal d, e, f, lntercuspal positions after
Orthodontic treatment in adults with TMJ dysfunction 557
positions treatment.
before treatment. g, Lower dental
Note buccal cross-bite arch after treatment.
of left premolars.
labial arch wire that tipped the left upper premolars lingually. After 13 months of treatment the cross-bite was corrected, with a stable intercuspal and retruded contact position. The patient was quite satisfied with this result. No attempts were made to treat the postnormal occlusion or the deep bite since this was not judged to be necessaryin order to achieve a functionally acceptableocclusion Uprighting of tipped molars Mesiolingual tipping of the lower second or third molar after loss of the first or second molar often creates an interference and may make preparation of the tooth for a bridge difficult or impossible. This was the case in the following patient.
550
Ingervull
Fig. 7. Case 6. a, lntercuspal position, left side, before treatment. b, Radiograph before treatment. c, Lower dental arch before treatment; note tipped left second molar. d, Lower dental arch during treatment, right first and left second molars uprighted. e, Radiograph after treatment. f and g, lntercuspal positions after treatment. h, Lower dental arch after treatment.
Volume 73 Number 5
Orthodontic
treatment in adults with TMJ dysfunction
559
Case 6 (Fig. 7). A 34-year-old man had lost his lower left first molar and this had given rise to a marked mesial tipping of the secondmolar. Tbe patient was aware of an increasedattrition of the left posterior teeth. These teeth were tender in the mornings. The left masseter muscle and temporomandibular joint was tender on palpation, and crepitation could be heard in both joints. A heavy balancing side interference was present between tbe lower left second molar and the upper left first molar. Orthodontic treatment was carried out with a lower labial arch wire with uprighting springs soldered to the right first and tbe left second molar bands. The uprighting took 4 months and was followed by the placement of bridges on both sides of the mandible and crowns in the maxillary lateral segments.The orthodontic treatment eliminated the patient’s occlusal interference, abolished his symptoms, and greatly facilitated the prosthetic treatment.
Discussion A great advantage of orthodontics for the elimination of cuspal interference in adult patients with functional disturbances in the masticatory system is that no tooth substance needs to be removed. Orthodontics is therefore the method of choice when grinding would have esthetic or functional drawbacks, for example, (1) in anterior cross-bites, (2) a large reduction of the occlusal relief, or (3) in patients with arch width discrepancies.
Another advantage of tooth movement is that the teeth can be placed in such positions that occlusal stability is achieved. Interfering teeth in cross-bite, for example, can be moved to new positions where they contribute to the occlusal stability of the dentition as a whole and where they cannot elongate. Mere grinding of the interfering teeth in cross-bite situations involves a risk of future elongation and recurrence of the interference. Another situation in which orthodontic treatment can contribute to the occlusal stability of the dentition is in the uprighting of tipped teeth, making a prosthetic reconstruction possible, as shown in Case 6. A common method for the correction of occlusal disharmony in cases where grinding
therapy is inappropriate has been prosthetic reconstruction with crowns or bridges. A prosthetic reconstruction is expensive, however, and involves the risk of pulp damage, secondary caries, and parodontal damage. A prosthetic reconstruction may also be esthetically less satisfactory than the patient’s “natural” teeth. Orthodontic and prosthetic treatment can sometimes he combined with advantage, the orthodontic treament facilitating prosthetic reconstruction and the prosthesis solving the problem of retention and thereby considerably reducing the treatment time. The cases presented are examples of orthodontic therapy in the treatment of patients
with functional disturbances of the masticatory system. This simple type of orthodontic treatment has led to considerable-in some cases dramatic-improvement for the patient. Mandibular dysfunction symptoms may, however, have a multicausal background, including mental factors and general disease in addition to occlusal disharmony. Obviously, therefore, orthodontic treatment cannot be expected to be successful in all patients but should be considered as a superior alternative to other forms of therapy in some patients. REFERENCES
I. Posselt,U.: Physiologyof Occlusionand Rehabilitation,Oxford, 1968,BlackwellScientificPublications. 2. Ramfjord,S. P., and Ash, M. M.: Occlusion,Philadelphia,1971,W. B. SaundersCompany. 8. Ingervall,B.: Functionallyoptimalocclusion:Thegoalof orthodontictreatment,AM. 1. ORTHOD. 70: 81-90, 1976. Faculty
of Oaimtology
(400-33
Ghborg
33)
Sweden
T
he most common methods for correction of occlusal disharmony in the adult dentition have been (1) selective grinding or (2) rehabilitation with fixed prostheses. Apart from these methods, textbooks describing the treatment of patients with functional disturbances of the masticatory system also mention orthodontic treatment as a means of eliminating occlusal interferences, stabilizing the occlusion, and creating favorable tooth contacts during gliding movements.lj 2 Occlusal disharmony is a purely functional concept and can occur in any morphologic malocclusion.3 Occlusal disharmony in certain types of malocclusion is difficult to correct by grinding or prosthetic methods but can relatively simply be treated orthodontically. This report is a description of typical cases in which orthodontic treatment was chosen. All of the patients were referred for orthodontic treatment from a department of stomatognathic physiology because the conventional methods of treatment used in that department (grinding and prosthetics) were less suitable in these cases. The aim of all methods of treatment is to correct the occlusion in order to abolish mandibular dysfunction and prevent its recurrence. During the acute phase of mandibular dysfunction symptoms, treatment methods such as splints, exercises, and heat treatment are often used regardless of the type of occlusal disharmony and possible morphologic malocclusion. Anterior cross-bite Most patients receiving orthodontic treatment of symptom-provoking occlusal disharmony have anterior cross-bite. Orthodontic treatment is preferred because (1) elimination by grinding of occlusal interferences of front teeth may be undesirable for esthetic reasons and (2) it may be impossible to achieve occlusal stability after grinding. That is, after the interfering tooth substance is ground away there is no occlusal stop (Fig. 1). The tooth may then elongate and a new interference will be created. Case 1 (Fig. 2). A 37-year-old woman had been referred to the department of stomatognathic physiology by her general dentist becauseof a 2 year history of intermittent right-sided facial pain. Clinical examination revealed tenderness to palpation of the right temporal muscle, the lateral pterygoid muscles, and the neck musclesbilaterally. There was also clicking in both temporomandibular joints. The upper right central incisor was in cross-bite, interfering
in the retruded mandibu-
*Department of Orthodontics, Faculty of Odontology, University of GSteborg OOiX-9416/78/0573-0551$00.90/O
0
The C. V. Mosby Co.
551
552
lngervnll
POSSibh el
a
b
Flg. 1. a, Anterior cross-bite before grinding. b, After grinding. It is rarely self-corrective. Elongation is more likely to occur.
lar position. The mandible was displacedanteriorly so that the anteroposterior distance between the retruded and intercuspal positions was 2 mm. Orthodontic treatment consistedof sagittal expansion of the upper dental arch with a labial arch wire, thus creating space for the crowded central incisor to move labially. Six months of this treatment corrected the malocclusion and abolished the patient’s pain and dysfunction symptoms. Despite the temporary use of a lower splint, the upper right central incisor became tender during the treatment and had to be relieved from some of the occlusal interference by incisal grinding. Case 2 (Fig. 3). A 35year-old woman complained of nocturnal bruxism and also clenching in the daytime in stress situations. In the mornings she experienced a feeling of fatigue in the temporomandibular joints and in the face. She had had a headacheevery day for the last 6 months. Numerous muscleswere tender on palpation-the temporal and lateral pterygoid musclesbilaterally, the right masseterand sternocleidomastoid muscles, and the left digastric muscle. The left temporomandibularjoint was also tender on palpation and there was clicking in both joints. The path of opening and closing movement as well as protrusion was irregular and the range of lateral and protrusive movements was somewhat limited. The patient had a skeletal mandibular asymmetry, causinga cross-biteof the upper left canine and first premolar. The canine interfered in the retruded position. This displaced the mandible to the left into the intercuspal position and tended to “lock” the occlusion. The upper lateral incisors were congenitally missing. The patient had been treated with a splint and movement exercises, which improved her condition but did not relieve the symptoms or solve her occlusal problems. Orthodontic treatment consisted of insertion of an upper labial arch wire, which opened up space for pontics replacing the lateral incisors and moved the upper left canine buccally. This treatment, lasting 9 months, eliminated the interference and the patient’s pain. After treatment, which concluded with the placement of two smah inlay bridges in the upper front, she had headache only about once a month. Case 3 (Fig. 4). A 4%year-old woman had had symptoms of functional disturbance of the masticatory system for more than 5 years. The symptoms were most pronounced in the mornings and consistedof dull aching in the left tempommandibular joint and in the masticatory muscles.She had periodic headacheand was aware of tooth clenching. There was locking of the mandible during movements and she was aware of bilateral temporomandibular joint clicking. The temporal and lateral pterygoid muscles bilaterally were tender on palpation, as were the right masseterand the left digastric muscles. The range of movement of the mandible was normal, but mandibular movements were painful.
Volume 73 Number 5
Orthodontic
treatment in adults with Th4J dysfunction
553
Flg. 2. Case 1, a and d, lntercuspal positions before treatment. b and c, Retruded contact positions before treatment. Upper right central incisor in cross-bite and interfering in the retruded position. e, 1, g, lntercuspal positions after treatment.
In the intercuspalposition the upper right canine and all incisorswere in cross-bite. The canine and the right lateral incisor interfered in the retruded position. The patient was treated at the department of stomatognathic physiology with a bite splint and short-wave heat therapy, but exerciseshad to be abandoned because of pain on movement. The splint, which was later replacedby bilateral cap splints in the lower jaw, stabilizedthe occlusion and reduced the patient’s symptoms but attempts to remove the splints caused recurrence of her headache. As permanent therapy, the anterior cross-bitewas eliminated by sagittal expansion of the upper dental arch with the aid of a labial arch wire combined with ClassIII elasticsto a lower labial arch. The occlusion was corrected in 5 months, resulting in complete disappearanceof the patient’s symptoms.
554
lngervall
Fig. 3. Case 2. cross-bite, upper canine interfering.
a and b, lntercuspal
positions before treatment. lateral incisors missing. c, Retruded contact d, e, f, lntercuspal positions after treatment.
Upper left canine and first premolar in position before treatment. Upper left g, Upper dental arch after treatment.
Arch width discrepsncies Another type of malocclusion in which orthodontic treatment can be of value is in cases of discrepancy between upper and lower arch widths. In such cases elimination of occlusal interferences by grinding may mean that large amounts of tooth substance have to be removed. Grinding also has to be done on practically all lateral teeth. This may be undesirable for psychological reasons, and it also involves the risk of reduced chewing
Volume 73 Number 5
Orthodontic
treatment in adults with TMJ dysfunction
555
Fig. 4. Case 3. a and b, lntercuspal positions, right and left sides, before treatment. All incisors and right canine in cross-bite. c and d, Before treatment, retruded contact positions. Upper right canine and lateral incisor interfering. e, f, g, lntercuspal positions after treatment.
efficiency because of flattened occlusal surfaces. A case of this type has been described previously3 and the following is another example. Case 4 (Fig. 5). A 17-year-old girl had had her symptoms for 3 months. They consisted of right-sided pain below and in front of the ear which was most severe in the mornings and was combined with difficulty in opening the mouth. The patient thought that she had a habit of clenching her teeth. Clinical examination revealed reduced mouth-opening capacity and that all mandibular movements were accompanied by pain in the right masseter region. The upper dental arch was narrow in relation to the lower, so that the intercuspidation was inadequate. There was a 1.5 mm.
556
.4m J Onhod
Ingervull
Fig. 5. Case
4. a and
b, lntercuspal
positions
before
treatment.
c and
d, lntercuspal
positions
after
treatment.
lateral shift of the midline between the intercuspal and retruded contact positions. Treatment was started with a splint and exercises. This reduced the pain on movement and brought about a slight increase in opening capacity. It was not possible to eliminate the cuspal interference through grinding because large amounts of tooth substance would have had to be ground away. Instead, the upper dental arch was widened transversely with an upper plate equipped with an expansion screw in the midline. The widening, which took 5 months, eliminated the lateral shift between the retruded and intercuspal positions and resulted in acceptable intercuspidation. This result still remained stable 1 year after cessation of retention, which lasted 6 months. All the patient’s dysfunction symptoms disappeared during the active expansion.
Buccal cross-bite (“scissors bite”) Posterior teeth in buccal cross-bite may cause serious cuspal interference during gliding movements. Attempts to abolish this interference by grinding often mean extensive grinding. Another limitation of this approach is that no occlusal stop is present after the grinding, with consequent risk of elongation and recurrence of the interference. In these cases, elimination of the interference by tooth movement is preferable. Case 5 (Fig. 6). A 19-year-old girl had only mild subjective symptoms, but she was unable to find a distinct intercuspal position, which she regarded as a problem. She was aware of nocturnal grinding and clenching in the daytime. Clinically, slight tenderness on palpation was found in the right temporal and lateral pterygoid muscles as well as on palpation of the right temporomandibular joint. She also had slight pain on both sides of the face during mandibular movements. The occlusion was postnormal and a space deficiency had displaced the lower left premolars lingually so that a buccal cross-bite relation was present between the upper and lower left premolars. The upper left premolars were tipped somewhat buccally. Muscle exercises eliminated the patient’s muscle tenderness and pain but she continued to complain of an indistinct intercuspal position. Orthodontic treatment consisted of sagittal expansion of the lower left dental arch with a labial arch wire. Simultaneously, an upper plate was fitted. This plate had a frontal plateau (bite plane) that temporarily disoccluded the posterior teeth. It also had a
Volume 73 Number 5
Fig. 6. Case 5. a, b, c, lntercuspal d, e, f, lntercuspal positions after
Orthodontic treatment in adults with TMJ dysfunction 557
positions treatment.
before treatment. g, Lower dental
Note buccal cross-bite arch after treatment.
of left premolars.
labial arch wire that tipped the left upper premolars lingually. After 13 months of treatment the cross-bite was corrected, with a stable intercuspal and retruded contact position. The patient was quite satisfied with this result. No attempts were made to treat the postnormal occlusion or the deep bite since this was not judged to be necessaryin order to achieve a functionally acceptableocclusion Uprighting of tipped molars Mesiolingual tipping of the lower second or third molar after loss of the first or second molar often creates an interference and may make preparation of the tooth for a bridge difficult or impossible. This was the case in the following patient.
550
Ingervull
Fig. 7. Case 6. a, lntercuspal position, left side, before treatment. b, Radiograph before treatment. c, Lower dental arch before treatment; note tipped left second molar. d, Lower dental arch during treatment, right first and left second molars uprighted. e, Radiograph after treatment. f and g, lntercuspal positions after treatment. h, Lower dental arch after treatment.
Volume 73 Number 5
Orthodontic
treatment in adults with TMJ dysfunction
559
Case 6 (Fig. 7). A 34-year-old man had lost his lower left first molar and this had given rise to a marked mesial tipping of the secondmolar. Tbe patient was aware of an increasedattrition of the left posterior teeth. These teeth were tender in the mornings. The left masseter muscle and temporomandibular joint was tender on palpation, and crepitation could be heard in both joints. A heavy balancing side interference was present between tbe lower left second molar and the upper left first molar. Orthodontic treatment was carried out with a lower labial arch wire with uprighting springs soldered to the right first and tbe left second molar bands. The uprighting took 4 months and was followed by the placement of bridges on both sides of the mandible and crowns in the maxillary lateral segments.The orthodontic treatment eliminated the patient’s occlusal interference, abolished his symptoms, and greatly facilitated the prosthetic treatment.
Discussion A great advantage of orthodontics for the elimination of cuspal interference in adult patients with functional disturbances in the masticatory system is that no tooth substance needs to be removed. Orthodontics is therefore the method of choice when grinding would have esthetic or functional drawbacks, for example, (1) in anterior cross-bites, (2) a large reduction of the occlusal relief, or (3) in patients with arch width discrepancies.
Another advantage of tooth movement is that the teeth can be placed in such positions that occlusal stability is achieved. Interfering teeth in cross-bite, for example, can be moved to new positions where they contribute to the occlusal stability of the dentition as a whole and where they cannot elongate. Mere grinding of the interfering teeth in cross-bite situations involves a risk of future elongation and recurrence of the interference. Another situation in which orthodontic treatment can contribute to the occlusal stability of the dentition is in the uprighting of tipped teeth, making a prosthetic reconstruction possible, as shown in Case 6. A common method for the correction of occlusal disharmony in cases where grinding
therapy is inappropriate has been prosthetic reconstruction with crowns or bridges. A prosthetic reconstruction is expensive, however, and involves the risk of pulp damage, secondary caries, and parodontal damage. A prosthetic reconstruction may also be esthetically less satisfactory than the patient’s “natural” teeth. Orthodontic and prosthetic treatment can sometimes he combined with advantage, the orthodontic treament facilitating prosthetic reconstruction and the prosthesis solving the problem of retention and thereby considerably reducing the treatment time. The cases presented are examples of orthodontic therapy in the treatment of patients
with functional disturbances of the masticatory system. This simple type of orthodontic treatment has led to considerable-in some cases dramatic-improvement for the patient. Mandibular dysfunction symptoms may, however, have a multicausal background, including mental factors and general disease in addition to occlusal disharmony. Obviously, therefore, orthodontic treatment cannot be expected to be successful in all patients but should be considered as a superior alternative to other forms of therapy in some patients. REFERENCES
I. Posselt,U.: Physiologyof Occlusionand Rehabilitation,Oxford, 1968,BlackwellScientificPublications. 2. Ramfjord,S. P., and Ash, M. M.: Occlusion,Philadelphia,1971,W. B. SaundersCompany. 8. Ingervall,B.: Functionallyoptimalocclusion:Thegoalof orthodontictreatment,AM. 1. ORTHOD. 70: 81-90, 1976. Faculty
of Oaimtology
(400-33
Ghborg
33)
