With the introduction of the “Seattle Protocol,” dentists can provisionally determine the biologically optimal occlusal appliance for each patient. The final appliance has been tested intraorally before final fabrication (read my “Choosing the Correct Nightguard: Let the Patient Decide” article for more details).

The ideal final appliance can come from any of the five major categories: stabilizing splint, anterior repositioning appliance (ARA), dual-arch, dual-arch ARA and mandibular advancement splint. As such, providers need to become more aware of splint designs not traditionally discussed in dental school. This article will describe the anterior repositioning appliance – an extremely successful splint design that you have probably never heard of.

Aspen appliance

molded appliance viewed from above

The anterior repositioning appliance was first reported in dental literature in 1951.1 That splint design covered the molars and premolars of the maxillary teeth with a palatal bar connector. The opposing teeth had small indentations in the acrylic, directing the maximum intercuspal position anteriorly.

The stated goal was to reposition a displaced temporomandibular joint disk into a normal load-bearing position. After healing, it was believed that the recaptured condyle-disk relationship could be walked back into the fossa and maintained by adjusting the biting surfaces of the ARA. Since that time, the designs have varied, but the dental goal of normalizing the condyle-disk relation remains the same.

In cases when the disk is recaptured with an ARA, it can eliminate pain and dysfunction. The literature is replete with evidence that ARAs have significant advantages over our traditional splint designs in those cases.2

However, the proof is limited that walking the position back without orthosis is possible. One study demonstrated 100% recapture of the disk on the ARA, but only 40.6% maintained that relationship once splint therapy was discontinued.3

There are two main mechanical concepts of how to choose the bite position for disk recapture: clinical and imaging. Clinical techniques include biting on a thickness of tongue depressors far enough protrusively to eliminate the click. The mandible is then retruded to just before the click. The patient holds at that point and bite registration is injected between the posterior teeth.

Farrar appliance

molded appliance viewed from the side

This method is 70% effective at capturing displaced disks without the aid of imaging.4 Utilization of arthrogram, CT scan and MRI improve the results in recapturing with an ARA.5 Of 56 patients fabricated an ARA using clinical references, 26 had disks that remained displaced. Those 26 had arthrograms to assist in guiding proper bite positioning. The image-guided splints were successful in recapturing disks in 22 of 26 patients. Using MRIs to determine effective positioning allowed a 96% recapture rate.

Disc recapture is the mechanical goal of an anterior repositioning splint. There are, however, “airway” advantages to the design, as well. The ARA has proven to be a valuable orthotic for patients presenting maxillary hypoplasia and nasal incompetency. Biologically, the 3-mm advancement of the protocol device has been proven to significantly reduce nasal resistance, increase nasal patency and improve the critical closing pressure of apnea patients. Females have been shown to be more responsive to these minor protrusive alterations.

Why was I not taught about the ARA? In my opinion, the reason that this technique is not taught more often is the fact that once the patient has been maintained in a subjectively pain-free and airway positive position for 3-6 months, their maximum intercuspal bite may change due to condylar remodeling. If so, their bite may need to be addressed orthodontically or restoratively to eliminate the need for the orthosis.6

These changes have only been observed in studies with 24/7 wear for a minimum of three months, or in studies where the ARA is defined as a dual-arch, mandibular advancement device worn at night as a sleep appliance. Even though nighttime wear of a single-arch orthosis has not been reported to alter the maximum intercuspal position, the protocol recommends daily morning repositioning of the bite with an AM Aligner (see “Seattle Protocol Step 5: Dual Arch Anterior Repositioning Splint” video lesson for details).

teeth holding in the appliance

Additionally, while ARA therapy followed by orthodontics to mimic the new bite has proved effective long-term, partial use of the appliance can provide symptom relief and negate the occlusal alterations seen with full-time utility.7

While it may be unfamiliar to many practitioners, the ARA design has a long, positive history. The literature is replete with evidence of its mechanical and biologic advantages. The Seattle Protocol allows practitioners to provisionally determine if the anterior repositioning appliance is appropriate before final fabrication.

Jeffrey Rouse, D.D.S., is a member of Spear Resident Faculty.


  1. Ireland VE: The problem of the clicking jaw. Proceedings of the Royal Society of Medicine. January 22, 1951:27.
  2. Lundh H, Westesson PL, Jisander S, Eriksson L: Disk-repositioning onlays in the treatment of temporomandibular joint disk displacement: comparison with a flat occlusal splint and with no treatment. Oral Surg Oral Med Oral Pathol 1988; 66:155-162.
  3. Chen HM, Liu MQ, Yap MQ, Fu KY. Physiological effects of anterior repositioning splint on temporomandibular joint disc displacement: a quantitative analysis J Oral Rehabil. 2017 Sep;44(9):664-672.
  4. Kurita H, et al.: Evaluation of disk capture with a splint repositioning appliance. Clinical and critical assessment with MR imaging. Oral Surg Oral Med Oral Pathol Oral Radiol Endodont 1998; 85:377-380.
  5. Simmons HC, Gibbs SJ: Recapture of temporomandibular joint disks using anterior repositioning appliances: an MRI study. J Craniomandib Pract 1995; 13:227-237.
  6. Liu, M Chen H, Jin Yap, Fu K, Condylar remodeling accompanying splint therapy: a cone-beam computerized tomography study of patients with temporomandibular joint disk displacement. Oral Surg Oral Med Oral Pathol Oral Radiol 2012;114:259-265
  7. Conti PCR, Miranda JES, Conti ACF, Pegoraro LF, Araujo CR. Partial time use of anterior repositioning splints in the management of TMJ pain and dysfunction: A one-year controlled study. J Appl Oral Sci. 2005;13(4):345-50