Abstract
Magnetic resonance imaging (MRI) studies on centric condyle positions lack 3D comparisons of guided and unguided methods, which are used for accomplishing centric relation reference positions. The purpose of this study was to describe the space, in which mandibular condyles are placed in vivo by dental intercuspation, Dawson’s bimanual manipulation, and neuromuscular position. Twenty asymptomatic individuals aged 23 to 37 years underwent separate bite registrations using bimanual manipulation and the unguided neuromuscular technique. Subsequent 3-Tesla MRI scans of both temporomandibular joints yielded 3D data of the most superior condylar points at maximum intercuspation and both centric relation positions. We found concentric condyle positions in maximum intercuspation but considerable variation of condyle position after bimanual manipulation and neuromuscular technique. Their 95% predictive confidence ellipses overlapped substantially and created a space of reference positions. Its smallest volume averaged 2 mm3 for a minimal convex hull (95% confidence interval 1.1–3.2) and 3.5 mm3 for a minimal ellipsoid hull (95% confidence interval 1.8–5.4). Visualized in vivo by MRI, condyle positions at bimanual manipulation and neuromuscular position were not predictable and showed substantial variation in asymptomatic subjects. Clinicians should be aware of the functional space and its effect on dental intercuspation.
Highlights
Assessment of dental intercuspation is part of the clinical examination of the craniomandibular system
Two magnetic resonance imaging (MRI) studies analyzed intercuspal position (ICP) and guided RPs10,11 but without MRI visualization of condyle positions achieved by an unguided technique
The null-hypothesis stated no difference between bimanual manipulation (BM) and neuromuscular method (NM) in 3 spatial planes
Summary
Assessment of dental intercuspation (intercuspal position, ICP) is part of the clinical examination of the craniomandibular system. In the past most knowledge about condylar position has originated from roentgenographic studies (transcranial head film, orthopantomogram, conventional and computed tomographies). These direct methods do not characterize soft tissues and cartilage, same as scintigraphy. For comprehension of the effects of BM and NM on condyle and disk positions in vivo, magnetic resonance imaging (MRI) fulfills the requirement of a direct method for hard and soft tissues. A diagnostic gold standard, research on centric condyle positions with MRI has been rare. Two MRI studies analyzed ICP and guided RPs10,11 but without MRI visualization of condyle positions achieved by an unguided technique. The null-hypothesis stated no difference between BM and NM in 3 spatial planes
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