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Purpose of Anterior Repositioning Appliances

The purpose of anterior repositioning appliances is to address disc displacement, restoring the disc to a more normal anatomical position (when possible) and allowing the associated skeletal muscles to return to their resting lengths thereby minimizing myogenous pain.
The disc cannot be returned to its normal position and be stabilized in that position unless the mandibular condyle is also in its normal position.

According to the AACP, Centrist Relation is defined as the relationship of the mandible to the maxilla when the mandibular condyles are orthopedically aligned in the physiologic normal most stable position. This occurs when the condyles are in their most anterior/superior position resting with the discs properly interposed against the posterior slope of the articular eminences.
The condyles are resting in the center isthmus area of the articular discs. Anterior repositioning appliances, therefore, achieve the orthopedic definition of Centric Relation when the articluar disc is recaptured.

In pre-clicking and clicking joints, the condyle is displaced too far posteriorly as evidenced radio- graphically but the loss of posterior joint space. Controversy rages among clinicians about the proper position of the condyle. The condylar position, in the normal joint, should be centered in the joint as according to Gelb’s 4/7 position. The ACCP's philosophy is that condylar position is not an exact or specific point, but like all other biological systems, has a bio-adaptive angle of normal functionality. The Academy’s philosophy continues to hold that a condyle that is centered in the mandibular fossa is located in the mort posterior acceptable position, and a condyle placed in the Gelb 4/7 position is located in the most anteriorly recommended position. These positions result in a 2-3mm physiological range for condylar placement in treatment again, with the articular disc securely interposed between the anterosuperior surface of the condyle and the posterior slope of the articular eminecia when the teeth are in habitual occlusion.
Descriptions of various type of mandibulor repositioning appliances, their fabrication and application to patients have consistently apprehended in scientific dental literature for the past century. These appliances attempt to change a patients presenting symptomatic and dysfunctional maxiollomandibular relationship to one that is more normal, less symptomatic and more fully functional, repositioning the mandible vertically, anteroposterily and transversely to the exact necessary.

The concept of three dimensionally repositioning the mandible also encompasses the concepts of getting the muscles of mastication to their resting lengths and interposition of the TMJ disc between the anterosuperior surface of the condyle and the posterior slope of the articluar eminence in all mandibular excursions.
Temporomandibular joints which have been internally deranged for a duration greater than 2- 3 months have usually lost their superior joint space due to the chronic and sustained contraction on the masticatory elevator muscles and irreparable damage to the elastin in the retrodiscal tissues. At the same time this occurs, the dental occlusion adapts to the change in condylar position. With the condyle displaced superiorly and usually posteriorly, little or no joint space exists for the disc to go back to its normal, anatomical position. The disc cannot attain its previous normal position and the joints distal space is lost subsequent to the chronic internal disc derangement. Therefore, the very first and most basic requirement when treating a chronically deranged joint is to reestablish superior joint space. Without doing so, there is no space to which the disc can return. Since the dental occlusion has adapted to the disc displacement and condyle displacement, there is usually a posterior open bite when re-establishing normal condyle and disc position.

Indications for Use of Anterior Repositioning Appliance Therapy

The consensus on indications for ARA therapy is growing. Following are excerpts from peer reviewed articles and texts on the indications for ARA therapy that substantiate this growing acceptance. Gelb and Gelb stated that the indications for mandibular orthopedic repositioning appliances include:

1. anterior displacement with reduction
2. anterior displacement without reduction
3. tension- type headache, chronic daily headache with trigeminal input
4. myofascial pain( cervical and masticatory)
5. myalgia( cervical and masticatory) secondary to trauma, Para function or postural
6. hyper tonicity
7. reflex splinting or trismus
8. osteoarthrosis
9. osteoarthritis
10. tinnitus
11. vertigo

Gelb and Gelb went on to state that all studies show that repositioning therapy is more effective that flat plane or placebo appliance therapy in eliminating pain and joint noise, and in improving range of motion.
Okeson observed that the primary indication for anterior positioning appliance theory is acute joint pain associated with the disc displacement with reduction. In their textbook, Pertes and Gross opined anterior disc displacement therapy is primarily indicated in those cases of anterior disc displacement with reduction when the disc is thought to be the source of pain.
Grummons reported that with pain or clicking, treatment typically begins with an anterior repositioning appliance. Repositioning seems appropriate for TMJ clicking, locking, retrodiscitis or arthralagia.
Simmons and Gibbs found that ARA therapy provided effective pain relief regardless of disc status. Although a greater degree of relief was achieved in reducing internal derangements that were recaptured.

Dual Appliance Use During Anterior Repositioning Appliance Therapy
There is a consensus of opinion on appliance design and the wearing schedule for ARA therapy. This is based on extensive literature which supports use of mandibular appliance during waking hours and a maxillary appliance during sleep. Bledsoe stated that perhaps the most critical aspect of successful appliance management is knowing when to use dual appliance therapy. Dual appliance therapy is the use of two different appliances (one for daytime wear and another to be worn while sleeping) in the treatment of the same patient during the same period of time.
Dual appliance therapy is also the perfect answer for the practitioner who is concerned about the possibility of segmental appliances depressing teeth (especially as a result of nocturnal pathological bruxism). Alternation of appliances also allows the gingival tissues to have some time each day when they are not in contact with acrylic and this may prevent a decline in oral health. Ireland recommended a maxillary or mandiubular appliance with defined indents to anteriorly reposition the mandible to eliminate the freeway space.
Gelb previously recommended a mandibular orthopedic repositioning appliance with an uncovered lingual bar (i.e Gelb appliance) to be worn 24hours a day. He now recommends the same appliance during the waking hours and a Farrar appliance during sleep. The Farrar maxillary appliance includes full coverage of the maxillary teeth with an anterior ramp extending to and occluding with the lingual surface of only the manidbular anterior teeth, made to the same occlusal and vertical position as the Gelb appliance, and is an ideal complement. Using the Farrar appliance during sleep with conjunction with the Gelb appliance while awake greatly enhanced the efficacy of patients progress.
Farrar recommended the exclusive use of maxillary appliance with a small anterior flange extending behind the mandibular anterior teeth to be work 24 hours a day. However, this significantly impairs the patient’s ability to eat and speak normally.
Kaplan and Assael opined that a practical solution that employs the advantages of each type of appliance is the mandibular appliance during the day, in order to promote full time use and to minimally interfere with the patient’s daily activities, and the use of a maxillary appliance during the night, to better protect against the potential harmful effects of bruxism.
Pertes and Gross recommended that because repositioning appliances are usually worn on a full time basis, it is often necessary to alternate between a maxillary appliance at night and a smaller mandibular appliance during the day.

Superiority of ARA Therapy to Plat Plane Therapy
Lundh et al. evaluated 70 patients with internal derangements or an abnormal relationship of the articular disc to the mandibular condyle. They divided treatment to include 1) anterior repositioning appliance therapy 2) flat plane therapy and 3) a control group with no appliances. Both appliance groups has reduced joint tenderness, nut the anterior repositioning group demonstrated a significantly greater improvement with respect to internal derangements and symptoms.
Anderson et al. divided 20 patients with internal derangements into two groups and treated one group with maxillary flat plane appliances and the other group with anterior repositioning appliances. After 90 days. The anterior repositioning group experienced a significant reduction in dysfunction and symptoms, the flat plane group experienced no change in dysfunction and two of the patients progressed to closed lock (disc displacement without reduction).
In 2002, Brown and Gaudet published a long term multi-site study of 2,104 treated, 250 untreated and 44 long term treated TMD patients as a part of a continuing effort to study TMD treatment efficacy in a large patient population. A valid and uniform assessment of treatment validated and uniform assessment of treatment outcomes, the TMJ scale. Each dentist was calibrated on the use of the TMJ scale and the study criteria before the study began. This paper showed that untreated TMD patients did not improve spontaneously over time and that patients treated with a variety of active modalities achieve clinically and statistically significant levels of improvement. The use of anterior repositioning appliance theory produced superior results compared to flat plane appliance therapy.

References
Anderson GC, Schulte JK, Goodkind RJ : Comparative study of two treatment methods for internal derangement of the temporomandibular joint J Prosthet Dent 1985; 53 (3): 392-397

Kaplan AS, Assael LA : Temporomandibular Disorders Diagnosis and Treatment Philadelphia: W.B. Saunders Co.: 1991

Farrar WB, McCarty WL: A Clinical Outline of TMY Diagnosis and Treatment Montgomery (AL): Normandie Study Group Publications, 1982.

Simmons HC, 3RD, Gibbs SJ: Recapture of Tempormandibular joint disc using anterior repositioning appliances: an MRI study. J Craniomand Pract 1995; 13 (4):227-237

Simmons HC, 3RD, Guidelines for anterior repositioning appliance therapy for the management of craniofacial pain and TMD. J Craniomand Pract 2005; 23(4): 300-305

Brown DT, Gaudet EL, Jr: Temporomandibular disorder treatment outcomes: second report of a large- scale prospective clinical study, J Craniomand Pracy 2002: 20(4); 244-253
Gelb M, Gelb H : Gelb appliance: mandibular orthopedic repositioning therapy. In: Bledsoe WS, Jr., ed: Intraoral Orthotics. Baltimore: Williams & Wilkins, 1991.

Okeson JP: Orofacial Pain Guidelines for Assessment, Diagnosis and Management, Chicago: Quintessence Publishing Co., 1996

Pertes RA, Gross SG: Clinical Management of Temporomandibular Disorders and Orofacial pain Chicago: Quintessence Publishing Co., 1995

Grummons D: Orthodontics for the TMJ-TMD Patients. Costa Mesa: Wright and Co., 1994

Bledsoe WS. Jr: Selection, application and mangemtn phase 1 Orthotics. In: Bledsoe WS. J red Intraoral Orthotics. Baltimore; Williams and Wilkins 1991.

Gelb H: Effective managment and treatment of the craniomandibular sundrome. IN: Gelb H. ed: Clinical Management of Head Neck and TMJ Dysfunction. Philidelphia: W.B. Saunders Co., 1977

Laundh H, Westesson PL, Kopp S. Laskin DM, McNeill C: Council on Dental Care Programs. Prepayment plan benefits for tempormandibular joint disorders. J Am Dent Assoc 1982; 105(485-488)

Okeson JP: Management of Tempormandibular Disorders and Occlusion. 3rd ed: Mosby Year Book, 1993.