Restoring the Edentulous Patient With Oromandibular Dystonia: Treatment Planning Considerations and a review of the Current Literature

Oromandibular dystonia (OD), is considered a rare focal neurological disorder that affects an individual’s lower facial muscles.  Muscle groups affected by the disorder include the masticatory, tongue, and facial muscles.  The documented prevalence of OD is 6.9 out of 100,000 individuals and occurs predominantly in women between the ages of forty to seventy years.  Patients who suffer from this disorder display involuntary, repetitive, and sustained spastic movements of these muscles.  This results in parafunctional movements such as bruxing and clenching².  OD patients often have painful opening, closing and deflecting of the mandible related to temprormandibular joint pain.  In particular, those affected may be predisposed to early edentulism and occlusal alterations that may worsen dystonic movements and contribute to temporomandibular joint disorder³.  This combination may present a challenging scenario for those rehabilitating the edentulous patient with OD.

A PubMed literature search was conducted using the key phrases “oromandibular dystonia” and “oromandibular dystonia” + “implants.” Search results yielded many articles on OD in many different journals, but there was only one noted to document an OD patient restored with implants.  We present a 45 year old female with early edentulism and severe atrophy of the maxilla and mandible.  She had been previously diagnosed with OD and under the care of a Neurologist for several years.  Prior to presentation, the patient had undergone reconstruction of the mandible with an implant supported overdenture with the “All on 4” technique.  At that time, a new conventional maxillary complete denture was fabricated.  Clinical and radiographic exam at our institution revealed mandibular implant and prosthetic failure.  All of the mandibular implants were mobile with significant pain.  A panographic radiograph revealed bone loss around all of the implants.  Clinical exam also showed characteristic display of spastic jaw movements and tongue thrusting against the prosthesis.  It was deduced that these parafunctional movements had likely contributed to the failure.   

The patient underwent removal of the implants under IV sedation.  As her mandibular bone healed, she concurrently received Botox injections for the OD.  The patient reported that her parafunctional habits improved after the Botox therapy.  Intramuscular Botox injections have been utilized as the treatment of choice for symptom relief for OD¹.  Approximately three months after we explanted the hardware, the patient underwent implant restoration of the mandible.  A total of four implants were conventionally axial positioned in conjunction with allograft bone.  The patient was restored with a removable prosthesis with locator attachments.  Her prosthesis has proven to be successful and the implants are integrated without any signs of failure.

  When reviewing this case and contemplating reasons for failure of the patient’s prosthesis, it must be considered that the angulation of the implants along with the immediate loading protocol could have caused prosthetic failure.  Involuntary and parafunctional movements are another potential reason for failure.   Several factors related to positioning and load transfer along with direction of the forces may have produced an environment for the implants to fail ⁴.  A recent study by Penarrocha concluded that implants immediately loaded failed more often than those loaded conventionally.  The same study proposed that immediate loading of implants in patients with parafunctional movements may be contraindicated⁴.  It is important to understand that dystonic movements and parafunctional habits may result in implant failure when treatment planning the severely atrophic,  edentulous, OD case.  In conclusion, several factors such implant positioning, time of loading, bone grafting and parafunctional movements all need consideration when treating these patients.  Conventional techniques including delayed loading, axial implant placement and Botox injections to reduce dystonic movements may lead to a more predictable rehabilitation plan for these patients.