Condition category
Digestive System
Date applied
Date assigned
Last edited
Prospectively registered
Overall trial status
Recruitment status
No longer recruiting

Plain English Summary

Background and study aims
The cause of long-term disorders of the jaw joint called chronic temporomandibular joint disorders (TMD) is unknown and therapy is usually not predictable. Because the risk factors for TMD include contact between teeth that hinders normal movement and habitual chewing on the affected side, this study attempts to find out the effect of the therapy in restoring jaw closure and improving chewing.

Who can participate?
Adults age 18-65 with TMD who are suffering from pain can take part in this study.

What does the study involve?
Patients will be randomly allocated to one of two groups: active therapy and placebo (dummy treatment). Patients allocated to the active therapy group will have their premature teeth contact rectified. Patients allocated to the placebo group will be subjected to a similar procedure but tooth enamel will not be removed.

What are the possible benefits and risks of participating?
The benefits are that the therapy could completely eliminate or reduce pain and/or help with alteration of limited mouth opening. It may help the joint return to its normal position (not always achieved) and to prevent an increase in joint, muscular and dental damage. The only risk or inconvenience appear to be from the grinding down of the enamel, which is irreversible. Hypersensitivity could occur during the treatment. If this were to occur, your treatment would be stopped immediately. This may mean that you would not be able to eat vigorously, which is what is hoped for, the treatment could therefore be ineffective.

Where is the study run from?
University of Santiago de Compostela (Universidad de Santiago de Compostela) (Spain)

When is the study starting and how long is it expected to run for?
July 2014 to June 2016

Who is funding the study?
Ministry of Science and Innovation of the Government of Spain

Who is the main contact?
Prof Urbano Santana-Penin

Trial website

Contact information



Primary contact

Prof Urbano Santana-Penin


Contact details

Universidad de Santiago de Compostela
Facultad de Medicina y Odontología
C/ Entrerrios s/n
Santiago de Compostela
+34 (0)647 344 093

Additional identifiers

EudraCT number number


Protocol/serial number

UTN: U1111-1134-0832

Study information

Scientific title

Restoring physiological jaw closure and MAsticatory function as treatment for chronic Pain: a randomized clinical trial



Study hypothesis

Current hypothesis as of 04/05/2016:
That the restoration of physiological jaw closure and impaired chewing function by occlusal adjustment therapy will relieve chronic TMD-pain. Efficacy will be demonstrated by showing significantly superior pain relief at the 6-month visit with active treatment as compared with placebo.

Previous hypothesis:
The primary endpoint will be the average change in pain score from baseline to the 3- and 6-months assessments. Efficacy will be demonstrated by superior pain relief with the active treatment compared with the placebo.

Ethics approval

Autonomic Committee of the Research Ethics of Galicia, updated on 29/11/2013, CAEI approval number 2009/017

Study design

Interventional single-centre, randomized, single-blind, blinded assessment, placebo-controlled, open-label, controlled study

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please use the contact details below to request a patient information sheet


Facial pain: Chronic temporomandibular joint (TMJ) disorders (TMD)


Active therapy will consist of the elimination of premature tooth contacts and the reduction of the steeper lateral anterior guidance. Placebo therapy will be conducted in a manner identical to the active adjustment, but no enamel will be removed.

Added 09/05/2016:
Interim analysis plan and stopping rules:
The Data and Safety Monitoring Board will be responsible for activating early stopping. The study will employ an interim analysis plan with a single interim analysis after 70% of participants have completed the six-month follow-up visit. Using the Lan-DeMets version of the O'Brien-Fleming stopping rule, the critical value for statistical significance at the interim analysis (under intention-to-treat approach) will be +2.438, corresponding to a nominal two-sided P value of 0.0146.

Intervention type



Drug names

Primary outcome measure

Current primary outcome measures as of 04/05/2016:
Self-reported affected-side pain-intensity across the trial (baseline, 3- and 6-Months) on a 0–10 numerical rating (NRS) or visual analogue (VAS) scales (0 = no pain, 10 = worst possible pain). One after-MAP time: 9-12-Months after therapy is anticipated. Independent assessment. According to Comet Initiative, this outcome assessment follows the IMMPACT guidelines (DOI: 10.1016/j.pain.2004.09.012).

Previous primary outcome measures:
Self-reported pain intensity on the affected side. Measurement method: visual analogue scale (VAS); 0 = no pain, 10 = worst imaginable pain. Time points: baseline, 3 months and 6 months follow-up.

Secondary outcome measures

Current secondary outcome measures as of 04/05/2016:
1. Maximum unassisted jaw opening, using a Boley gauge. Limited if ≤38 mm (females) or ≤40 mm (males)
2. Chewing function (alternate vs. one habitual chewing side):
2.1. Clinically observed habitual chewing side (if at least 7/10 almonds by the same side); alternately, observing the lateral bolus of chewing-gum placement during chewing tests (Christensen & Radue, 1985)
2.2. Interview: actual and retrospective chewing function (Diernberger et al., 2008)
3. Quality of life assessed by the self-administered Spanish validated questionnaire SCL-90-R (Derogatis et al., 1976; González de Rivera et al., 1989)

Previous secondary outcome measures:
1. Maximum unassisted mouth opening (using a Boley gauge)
2. Chewing function (observed: alternate vs one habitual chewing side)
3. Quality of life using self-administered tests
Time points: baseline and 3 months and 6 months follow-up.

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

Current inclusion criteria as of 04/05/2016:
1. Pre-screened patients satisfying the TMD-pain instrument (Gonzalez et al., 2011); TMD-pain diagnosis requires each of two findings: pain of sufficient frequency across a recent period and modification of the pain by jaw function. Assessors (JLC, FLF, MPC) will apply this instrument for eligibility
2. Patients suffering self-reported significant chronic TMD-pain (Joint and/or Muscle pain) according to DC/TMD (Schiffman et al., 2014)
3. Aged 18–65 years
4. Completely dentate adults with normal (or adequately restored with fixed crowns or bridges) occlusion
5. Suffering from significant TMD-pain (≥4 and ≤9 scores, in a 0–10 visual and/or numerical analogue scale-VAS/NRS; 0 = no pain to 10 = worst possible pain)
6. Had requested therapy for TMD-pain, referred to the Hospital/University Service
7. After more than 6 months of treatment with conservative therapies

Previous inclusion criteria:
TMD patients, aged 18-65 years with full dentates and normo-occlusion suffering significant pain (pain scores ≥4 and ≤9; method: visual analogue scale (VAS); 0 = no pain, 10 = worst imaginable pain)

Participant type


Age group




Target number of participants

A total sample size of 88 subjects (extended to 110 for drop-outs), 44 or more per arm group

Total final enrolment


Participant exclusion criteria

Current exclusion criteria as of 04/05/2016:
1. Psychosis
2. Major depression
3. Substance abuse
4. Cognitive impairment
5. Addiction to morphine or derivatives
6. Litigation or asking for disability/retirement compensation for chronic pain
7. Dental care professionals
8. Orthodontic therapy during the last 2 years
9. Degree 2 to 3 of tooth mobility
10. Patients with any pain that is more severe, in the same location as, or cannot be clearly distinguished from TMD pain
11. Individuals for whom minimally-invasive occlusal adjustment could not achieve occlusal equilibration (assessed by the experts in occlusion, Drs. USM, MJM), to minimize tissue removal. Over 2 mm of difference between the maximal intercuspal position and the centric occlusion; and/or over 4 mm (2 mm on any side) of difference between upper and lower arches measured: between the mesial fossae of the first upper premolars with respect to the cusps of the first lower premolars; and the mesiopalatal cusp of the first upper molars with respect to the central fossae of the first lower molars. A Boley gauge (Beerendonk, nº REF 042-750-00; Dentaurum GmbH & Co., KG, Ispringen, Germany) will be used for these intraoral measurements
12. No periodontal disease (except for chronic severe cases with grade 2–3 mobility), fibromyalgia nor neuropathic pains are exclusion criteria

Previous exclusion criteria:
Main exclusion criterion is the requirement of excessive enamel removal to equilibrate the dental articulation (occlusion)

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

Universidad de Santiago de Compostela
Faculty of Medicine and Dentistry
Santiago de Compostela

Trial participating centre

The University Hospital Complex of A Coruña
Service of Oral and Maxillofacial Surgery
A Coruña

Sponsor information


University of Santiago de Compostela (Universidad de Santiago de Compostela) (Spain)

Sponsor details

c/o Urbano Santana-Penin
Facultad de Medicina y Odontología
C/ Entrerríos s/n
Santiago de Compostela

Sponsor type




Funder type


Funder name

Ministerio de Ciencia e Innovación (Grant no. PI11/02507)

Alternative name(s)

Ministry of Science and Innovation, Spanish Ministry of Science and Innovation, MICINN

Funding Body Type

government organisation

Funding Body Subtype

Federal/National Government



Results and Publications

Publication and dissemination plan

We will try to publish the results in a journal of the first decile JCR in September 2017.
Data remains stored in a repository Openclinica available (read only) to the DSMB of the trial. Data will be made available on request after study ending and published.

Intention to publish date


Participant level data

Stored in repository

Basic results (scientific)

Publication list

2013 results in:

Publication citations

Additional files

Editorial Notes

17/04/2019: The following changes were made to the trial record: 1. Publication reference added. 2. The total final enrolment was added. 04/05/2016: the following changes were made to the trial record: 1. The overall trial start date was changed from 15/07/2014 to 03/07/2014. 2. The overall trial end date was changed from 31/12/2015 to 30/06/2017. 3. The public title was changed from 'Occlusal adjustment therapy for chronic facial pain' to 'Improving chewing function to treat chronic pain' 4. The study design was changed from 'Phase III, randomised, single (extensible to up three) centre, 6-month parallel-group, patient- and observer-blinded, placebo-controlled clinical trial' to 'Interventional single-centre, randomized, single-blind, blinded assessment, placebo-controlled, open-label, controlled study.'