Mailing Address:
Peter F. Chase, DDS, Pacific Orofacial Disorders Center Facial Pain Research
University of the Pacific School of Dentistry
2155 Webster Street, Room 615
San Francisco, CA 94115
(415) 929-6611

Dr. Peter F. Chase is an Associate Professor of Pathology and Medicine, and Director of the Facial Pain Research Center at the University of the Pacific Dental School in San Francisco. He is a Fellow in the Academy of General Dentistry, Diplomat of the American Academy of Pain Management, and a Fellow of the International College of Craniomandibular Orthopedics. He has lectured extensively on musculoskeletal dysfunction of the head and neck. Dr. Chase has maintained a private practice since 1975.

Dr. Rosalind N. Donoghue is a past Assistant Clinical Professor of Diagnostic Science at the Facial Pain Research Center, University of the Pacific Dental School in San Francisco. She currently maintains a private general dental practice in Southern California.

Abstract

In attempts to relieve jaw related pain complaints commonly referred to as TMD, two techniques are commonly used in establishing a more optimal, functional jaw posture, (1) a jaw posture established through use of a maxillary orthotic and (2) a jaw posture established through ultra low frequency (ULF) Transcutaneous Electrical Nerve Stimulation (TENS). It is theorized that given a selected end point, their position would be the same, regardless of therapy used. The purpose of this pilot study is to compare the eventual jaw measurements achieved by the two techniques. This was done by measuring the resulting mandibular position on two planes. Seven adults diagnosed as suffering from masticatory muscle pain (myofascial pain disorder) and joint pain/dysfunction (internal joint derangement) participated in the study. Initially, a baseline acquired centric occlusion bite was taken at initial dental contact and mounted on an articulator. Then, an involuntary TENS bite was taken using electrical stimulation (TENS) of the muscles of mastication recording initial dental contact and mounted on the articulator. Patients then began wearing a flat plane orthotic to be worn and adjusted over eight weeks. At the end of this period, a voluntary bite registration was taken at initial dental contact and mounted on an articulator. The acquired bite was used as the "0" baseline to which the bioelectric and orthotic generated bite was compared. The statistical results did not support the theory that ULF Transcutaneous Electrical Nerve Stimulation (TENS) and flat plane orthotic (FPO) techniques necessarily achieve the same maxillomandibular relationship.

Temporomandibular disorders (TMD) involve the masticatory musculature, the temporomandibular joint (TMJ), and associated structures. TMD is regarded as a subclassification of musculoskeletal disorders. Pain associated with these disorders may involve the muscles, nerves, joints (TMJs), vasculature, and teeth. Masticatory muscle pain, joint pain, and dysfunction are the most common findings in temporomandibular disorders (TMD). It has been suggested that a mandibular posture, free of abnormal muscle function, is fundamental to resolution of temporomandibular disorder pain and dysfunction (1).

Two muscle education methods (muscle relaxation techniques) share a similar objective of mandibular positional or postural realignment. One method is the maxillary flat plane acrylic intraoral orthotic. Mandibular realignment is one of the theories that explains the effectiveness of this appliance (3,6,7). The other commonly used technique employs ultra low frequency (ULF) Transcutaneous Electrical Nerve Stimulation (TENS) of the masticatory musculature to realign mandibular posture (9&10).

Treatment success has been reported for both the flat plane orthotic (FPO) and TENS procedures (6-10). Anterior/lateral/vertical mandibular repositioning from centric occlusion is common in both techniques and studies with both techniques show reduction of pain and dysfunction with change in the mandibular posture (11-13).

For this study, it is hypothesized that both techniques are locating the same mandibular position or posture as an explanation for their alleged successful therapeutic outcomes. The purpose of this study is to test this hypothesis by comparing the jaw positions of patients following the use of each technique.

Seven patients between the ages of 25 and 45 participated in this pilot study. The sample includes one male and six female patients of the Facial Pain Research Center at the University of the Pacific, School of Dentistry. Participants were diagnosed by this writer using standard diagnostic criterion as having a masticatory myofascial pain disorder and a bilateral or unilateral temporomandibular joint internal derangement Type IA (joint sounds without joint pain) or Type IB (joint sounds with joint pain). Excluded from this study were those patients diagnosed with existing "locked jaw" conditions, post-surgical cases involving the jaw, and those patients with jaw fractures or major growth anomalies.

Dental molds/impressions were taken and models were mounted on a modified Logic I Articulator (EOP Inc.) with face bow mounting. Centric occlusion, the acquired bite relationship (initial dental contact), was taken at the first appointment and used as baseline for further comparisons. At the same appointment, an involuntary bite registration (initial dental contact) was then taken following 45 minutes of Transcutaneous Electrical Nerve Stimulation (TENS) (Myotronics/Noromed Co.). On the second appointment, a maxillary flat plane orthotic (FPO) was delivered. This appliance was adjusted over a period of eight weeks. A bite registration (initial dental contact) was then taken. All bite registrations were taken with Blue Mousse (Parkell). The bite registrations were compared for each patient. The acquired bite was taken as the baseline to which the bioelectric and flat plane orthotic bite were compared. A modified Logic I Articulator with face bow mounting was used for this comparison. Measurements were recorded at each condylar axis in the anterior-posterior and vertical planes. All measurements were done by the one stated clinician.

Table 1 reports the deviations from baseline in millimeters for each patient when measured following Transcutaneous Electrical Nerve Stimulation (TENS) and following flat plane orthotic (FPO) application. Positive values represent more anterior or increased vertical positioning. Negative values represent more posterior or decreased vertical positioning. Pearson correlation coefficients have been calculated to investigate the extent of similarity between the maxillary jaw positions produced following TENS and FPO interventions. No association was found to be significant at the 5% or .05 level.

One explanation for the reported success of both Transcutaneous Electrical Nerve Stimulation (TENS) and flat plane orthotic (FPO) jaw posture techniques used in the treatment of temporomandibular disorders is the theory that both techniques allow the patient to reposture to an identical, more optimal jaw posture. Our findings do not support this hypothesis. Confounding variables affecting our results, which call for further studies include small sample size, limitations of measurement device, patient influence on bite registration technique, and limitation of effects on a single Transcutaneous Electrical Nerve Stimulation (TENS) therapy session.

It is theorized that a more optimal jaw posture may relieve TMD related pain complaints and dysfunction. Two commonly used techniques for obtaining a more optimal jaw posture include bioelectric (TENS) and a flat plane oral orthotic. This investigator hypothesized that both techniques would arrive at the same more optimal, measured jaw postural change.

Seven patients were selected for this preliminary study. These patients were identified as temporomandibular disorder patients exhibiting signs/symptoms of masticatory muscle pain and jaw joint (TMJ) pain/dysfunction.

Jaw postural changes from Transcutaneous Electrical Nerve Stimulation (TENS) and jaw postural changes from flat plane orthotic interventions were compared to a baseline centric occlusion bite. Analysis of data did not reveal statistically significant measurement similarities between the bite registrations obtained with the two methods. This study did not support the theory that the two alternative techniques are consistent in arriving at the same jaw relationship.

Deviations of ULF Transcutaneous Electrical Nerve Stimulation (TENS) and flat plane orthotic (FPO) jaw postural measurements from the baseline ("0") acquired jaw posture measurement.

                                    Anterior/Posterior 

 Anterior/Posterior
    
                      Right                                                Left

                                    Vertical
    
                      Right                                                Left