Re-evaluation of human masticatory movements

―treatment of temporomandibular disorder (TMD) with physiotherapy including chiropractic procedures

Introduction

Masticatory movements are complicated movements based upon individual habits. In dental practice, mandibular movements have routinely been reproduced using an articulator(Fig.1~2). At present, various kinds of adjustable articulators are available which claim to be able to reproduce individual mandibular movements.

However, there are many indications that it is extremely difficult to reproduce individual masticatory function on an articulator.

This presentation investigates the reasons for this difficulty by undertaking clinical case studies of patients with temporomandibular disorder (TMD) treated with physiotherapy, including chiropractic procedures.

Figure 1 Figure 2

Case Report

Forty random cases were chosen from patients being treated for TMD over a three-month period.

Sex

　　Male: 15 cases (37.5％)　　　　　 Female: 25 cases (62.5％)

Age

＜20 years: 2 cases (5％)　 20~30 years: 15 cases (37.5％)　

30~40 years: 14 cases (35％)　　　 40~50 years: 6 cases (15％)

50~60 years: 2 cases (5％)　　 ＞60 years: 1 cases (2.5％)

Medical examination

＜”Abnormal mandibular movements” since it is the mandible doing the moving＞

12 cases (30%) exhibited abnormal mandibular movement.

Right: 8 cases (20%)　　 Left: 4 cases (10％)

＜Abnormal temporomandibular joint (TMJ) sounds＞

34 cases (85%) exhibited abnormal TMJ sounds on movement of the mandible.

Right and left TMJ: 15 cases (37.5%) Right TMJ: 12 cases (30%)　

Left TMJ: 7 cases (17.5%)

＜Arthralgia of TMJ＞

9 cases (22.5%) experienced arthralgia of TMJ on movement of the mandible.　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　

　　　 Anterior movement: 4 cases (10%) Right lateral movement: 5cases (12.5%)

Left lateral movement: 6cases (15%)　　　　　

＜Movement of caput mandibulae>

　 40 cases (100%) exhibited gliding of the caput mandibulae detected by palpation and X-ray examination （palmar）.

＜Muscle tenderness＞

40 cases (100%) reported muscle tenderness.

　 Tenderness of m. sternocleidomastoideus　

Right: 2 cases (5％)　 Left: 36 cases (90％)　 Right and left: 2 cases (5％)

　 Tenderness of m. trapezium　　　

Right: 2 cases (5％)　　 Left: 35 cases (87.5%)　　 Right and left: 3 cases (7.5%)

　 Tenderness of m. temporalis　　　

Right: 3 cases (7.5％) 　 Left: 7 cases (17.5%)　　 Right and left: 0 cases (0%)

　 Tenderness of m. masseter　　　

Right: 6 cases (15％) 　 Left: 7 cases (17.5%)　　 Right and left: 0 cases (0%)

＜Condition of shoulder＞

37 cases (92.5%) exhibited differences in their shoulder heights

　　 　 Right shoulder higher: 1 cases (2.5%)　　 Left shoulder higher: 36 cases (90％)

＜Condition of spine＞

40 cases (100%) displayed subluxation of the spine (including pelvis).

Subluxation of cervical and thoracic spine: 19 cases(47.5％)

　 Subluxation of cervical, thoracic and lumbar spine (including pelvis):21 cases (52.5%)

＜Study model＞

40 cases (100％) had malocclusions.

　 Attrition of the teeth: 35 cases (87.5%) Crowding: 14 cases (35%)

　 Edge-to-edge occlusion: １cases(2.5%)

＜Mental health problems＞

9 cases (22.5%) were classified as having mental health problems after undergoing transactional analysis.

Case 1

This patient was experiencing TMD caused by prosthodontic treatment. TMJ problems occurred following the construction of crowns and a denture at another clinic. Ｔhis patient complained troubles of TMJ after treatment of crown and denture in another clinic. After the TMD was treated, the prosthodontic work was redone (Fig. 3).

　　　Figure 3 Figure 4

Case2

This patient was also experiencing TMD caused by prosthodontic treatment. The patient complained of headache and pain in the lower left first molars after dental treatment at another clinic. There was evidence of heavy bruxism, and transactional analysis indicated that this patient suffered from mental health problems. The toothache in this case is caused by traumatic occlusion as a result of bruxism (Fig. 4).

Case 3

This patient was experiencing TMD caused by orthodontic treatment. Symptoms appeared in the TMJ following extraction of bicuspids during orthodontic treatment at another clinic (Fig. 5).

　　　Figure 5Figure 6

Case 4　

This Patient was experiencing TMD caused by occlusal treatment. The patient complained of headaches caused by heavy bruxism (Fig. 6). This patient exhibited infra-occlusion caused by severe attrition of the teeth (Fig. 6 right). This patient had previously been treated for the infra-occlusion. The occlusion was managed using splints (Fig. 6 center), and occlusal rehabilitation was then undertaken (Fig. 6 left).

Treatment Method

1 Treatment

1) Physiotherapy

All patients underwent physiotherapy, including chiropractic, light therapy electrotherapy and muscle energy technique.

(1)Chiropractic

After massage, the subluxated joint was adjusted using a diversified　technique.

Principal Adjustment Techniques

Cervical techniques: Two hand cervical extension and master cervical (Fig. 7)

Thoracic technique: Sitting thoracic extension：full nelson (Fig. 8)　

Lumbar technique: Ilio deltoid

Pelvic techniques: Ilio deltoid , ischial deltoid and pelvis deltoid

(2)Light therapy ・electrotherapy

After chiropractic treatment, the patients underwent light therapy and electrotherapy.

�@Light therapy (infra-red ray) applied to facial muscles

�AElectrotherapy (Low frequency current) applied to facial muscles (Fig. 9).

The application points were tender areas in facial muscles. In many cases these points corresponded to acupuncture points and trigger points.

(3) Muscles energy technique

　　　After light therapy and electrotherapy,　muscles energy technique (MET) was performed on the TMJ. Patients opened their mouths, closed their mouths, shiｆｔed their mouths to the right and left. This technique is very popular in osteopathy, and is similar to proprioceptive neuromuscular facilitation (PNF).

Figure7　 Figure8 Fugure9

2) Dental treatment

All patients also underwent some form of dental treatment including sprint fabrication, occlusal equilibration and prosthodontic or orthodontic treatment.

(1)Sprint fabrication（Fig. 10）

Sprints　were used in 40 cases (100%).

Figure 10

(2)Occlusal equilibration

Occlusal equilibration was used in 10 cases (25%) after the occlusion was managed by sprint.

(3)Prosthodontic treatment

Prosthodontic treatment was used in 1 case (2.5%) after the occlusion was managed by sprint and occlusal equilibration.

(4)Orthodontic treatment

　 Orthodontic treatment was used in 2 cases (5%) after the occlusion was managed by

sprint and occlusal equilibration.

3) Mental therapy

Four patients (10%) with mental health problems underwent mental therapy such as autogenic training and medical treatment with tranquilizers. However five patients (12.5%) with mental health problems were given no mental therapy.

　　Autogenic Training: 4 cases(10%) 　Medical treatment (tranquilizer): 3 cases(7.5%)

2 Progress of treatment

1) Term of treatment

3 months: 7 cases (17.5%)　 4 months: 4 cases (10%) 　5 months: 3 cases (7.5%)　　　　　　 6 months: 3 cases (7.5%) 7 months: 2 cases (5%) 　 8 months: 0 cases (0%)

9 months: 5 cases (12.5%) 10 months: 4 cases (10%) 11 months: 3 cases (7.5%)　　　　 　 12 months: 7 cases (17.5%) 13 months~: 2 cases (5%)

2) Progress of treatment

Most patients showed increased muscle relaxation and an improvement in their occlusal condition.

　 Improvement: 39 cases (97.5%) Aｇｇravation: 0 cases (0%)

　 Unknown progress because treatment was discontinued: 1 cases (2.5%)　

In addition, the position of the mandible and mandibular movements were changed. There were three patterns of change: type R, type A and type L.

�@ Type R

Type R (Fig. 11), in which patients shifted the position of mandible laterally to the right.

�A Type A

Type A (Fig. 12), in which patients shifted the position of mandible anteriorly.

�B Type L

Type L (Fig.13), in which patients shifted the position of mandible laterally to the

left.

Figure11-TupeRFigure12-TypeAFigure13-TypeL

Conclusion

The application of physiotherapy treatment including chiropractic procedures resulted in changes in the position of the mandible for all 40 TMD patients. Each case required adjustment of their sprints.

Changes in the position of mandible were also accompanied by changes in the hinge axis. In type R cases, the left caput mandibulae shifted laterally to the right. In type A cases, both caput mandibulae shifted anteriorly. In type L cases, the right caput mandibulae shifted laterally to the left. In cases such as these it is difficult to mount the models correctly on an articulator and it is not possible to accurately reproduce individual masticatory function.

While not every patient is able to decide on the position of the mandible, 25% of patients undergoing continued treatment for TMD reach a point where their occlusion is fixed and their sprints do not require adjustment. There is no muscular imbalance and musuclar tonus. In these cases, occusal equilibration is possible, and it is possible to mount the models on an articulator using a hinge axis and accurately reproduce individual masticatory function.

Therefore, to reproduce individual masticatory function on an articulator, it is important to carefully examine the patients’ mandibular movements to ensure that their occlusion is fixed.

Discussion

Gnathology relies heavily on the use of articulators. It is important to pay attention to changes in the position of the caput mandibulae in the TMJ, because the position of the mandible and mandibular movements are influenced not only by the framework of the bones and joints, but also by the muscles.

Many patients with TMD exhibit muscular tonus and muscle imbalance and tenderness. Patients with TMD show evidence of motor disturbance of the TMJ. I suggest that muscular tonus governs changes in the position of the caput mandibulae, since there are many muscles in mandible and these muscles take part in mandibular movements. For example, shoulder tightness results in changes in mandibular movements. The suprahyoid muscles extend from the mandible to the hyoid bone. The infrahyoid muscles extend from the hyoid bone to the breast bone and shoulder blades. Thus, the hyoid bone is linked to tightness in the shoulder when mandibular movements change. This phenomenon is evident in patients undergoing TMD therapy. Relief of shoulder tigetness leads to changes in mandibular movements, as well as changes to the position of the caput mandibulae and changes in the hinge axis.

These results highlight the shortcomings of the anatomical approach, and the need to incorporate physiological anatomy into the study of mandibular movement, given the importance of the maucalar component in TMD.