A data-supported reference position of the intermaxillary relationship: The stable orthopedic position for healthy individuals and for TMD patients

Starting point for this study was the assumption that centric slide could be an etiologic factor for a temporomandibular disorder (TMD). Centric slide must be considered as the mismatch between the ideal condylar alignment in the fossa and the maximal intercuspal position. Centric slide may be measured intraorally with a millimeter ruler or with plaster models mounted in an articulator. The former technique seems not very precise because the operator needs to make an interpretation of the increments in millimeters on the ruler and is a 2-dimensional approach. The latter technique demands sophisticated articulator equipment to measure the centric slide 3-dimensionally. There is no validated reference position for mounted models in an articulator; the operator may choose one of 7 different definitions of centric relation as provided in the Glossary of Prosthodontic Terms, or the maximal intercuspal position. The most recent definition of centric relation can be achieved with 2 different methods: bimanual manipulation or with a leaf gauge. Reproducibility of bimanual manipulation has been tested, reproducibility of the method with a leaf gauge lacks in the current literature. Evidence of reproducibility is not satisfactory to validate a reference position. A construct validity of a method to locate centric relation with a leaf gauge and elevator muscle contraction appears to be the most preferable choice to test reproducibility of musculoskeletally stable centric relation position. Evidence of reproducibility makes the method to locate this musculoskeletally stable centric relation position eligible to be tested in a randomized clinical trial to prove validity of this potential treatment position of choice.