• The primary efficacy objective is to assess whether the CID is non-inferior to the active control in treating TMDs. [ Time Frame: From consent through 3 months post-baseline visit ] [ Designated as safety issue: No ]
  
• The primary safety objective is to characterize the safety profile of the CID by collecting and reporting study-related adverse events. [ Time Frame: From consent through 3 months post-baseline visit. ] [ Designated as safety issue: Yes ]
  

• The secondary efficacy objective is to assess whether the CID is superior to the passive control treatment in treating TMDs. [ Time Frame: The timeframe is 3 months from the baseline visit. ] [ Designated as safety issue: No ]
  

After providing consent, subjects will be assessed as to whether they meet inclusion criteria for the study. Subjects will complete a 4 week diary to measure TMD symptoms by recording pain levels on a Visual Analog Scale (VAS) twice daily. Standardized Research Diagnostic Criteria (RDC) are used to classify types of TMDs. The formal assessment tool is known as the RDC/TMD. It is an empirically-based and operationalized system for diagnosing and classifying RDC/TMD using a biopsychosocial model of disease as a framework. The CMI/TMD(hereafter referred to as the CMI) is designed to provide a basis for evaluating the severity of TMD signs and symptoms. The CMI score is calculated from a dysfunction index (DI) and palpation index (PI). The majority of questions found in the CMI are also included in the RDC/TMD, with the exception of five questions. As part of the baseline medical history, all subjects will be asked the five questions that are included in the RDC/TMD but not included in the CMI. Data from the CMI and the five RDC/TMD questions will be combined in the database and scored according to scoring guidelines for the RDC/TMD in order to diagnose and classify TMDs for all study subjects. Subjects may be categorized in one or more of the three diagnostic groups, including muscle disorders (myofascial pain), arthralgia, and disc displacements with reduction. Subjects will have an examination using the CMI at their screening visit. Subjects who meet inclusion criteria will be randomized to one of three groups: The study device (Clayton Intra-aural Device (CID)) group, the mouth splint group, or the exercise group. Subjects in all groups will return to the clinic for a baseline visit, followed by visits at one month, two months and three months post-baseline to return their completed 4 week VAS diary and to complete follow-up testing. At the baseline visit, subjects will have a targeted physicial examination, with results documented by the investigator on the CMI questionnaire. Subjects will complete an in-office VAS score, a Modified SSI questionnaire, and will also complete the TMJ Scale, a questionnaire designed to measure possible improvement using a 10 point scale. At each follow-up visit, each subject will complete questionnaires (including the Modified SSI questionnaire and an in-office VAS score)and will have a targeted physical examination, with results documented by the investigator on the CMI questionnaire. At each follow-up visit, subjects will be issued a new monthly diary to complete for the VAS scores twice daily, (once in the morning before 10:00 a.m. and once before bed) as well as to track their device wearing time or exercise compliance, as applicable. At the three month follow-up visit, subjects will also complete the TMJ Scale. Adverse events will be assessed at each visit.