Correlation between a CR:MIP discrepancy and TMD research published
Well, after all these years, finally some evidence to support the impression that there is a direct link between a CR:MIP (or CR:CO if you prefer!) skid and the symptoms of TMD. Hallelujah!
Significant CR:MIP discrepancies were found in 73% of the TMD group and just 11% of the non-TMD group.
Here’s the abstract:
Acta Odontol Scand. 2010 Nov;68(6):368-76.
Correlation between centric relation:maximum intercuspation discrepancy and temporomandibular joint dysfunction.
He SS, Deng X, Wamalwa P, Chen S.
Department of Orthodontics, West China College of Stomatology, Sichuan University, Chengdu, Sichuan, China.
Abstract
OBJECTIVE: To investigate the relationship between centric relation-maximum intercuspation (CR-MI) discrepancy and temporomandibular joint dysfunction (TMD) in pre-treated orthodontic patients.
MATERIAL AND METHODS: The study involved an experimental group of 107 pre-treated orthodontic patients with signs and symptoms of TMD aged 18-32 years, and a control group of 70 students with no signs and symptoms of TMD aged 20-30 years. The psychological condition of subjects was evaluated using two standard questionnaires, and a clinical examination performed to assess masticatory musculature and temporomandibular joint (TMJ) function, and to establish the presence or absence of TMD. Helkimo indices, the anamnestic dysfunction index (Ai) and the clinical dysfunction index (Di), were determined. Dental casts were mounted on a semi-adjustable articulator in CR using a CR bite record taken by bilateral manipulation and verified by load testing and face bow records. Differences in condylar position between CR and MI in the three planes of space were determined using the condyle position indicator.
RESULTS: A positive CR-MI discrepancy, defined as a discrepancy exceeding 1 mm in the vertical or horizontal planes or 0.5 mm in the transverse plane, was found in 72.9% of the experimental and 11.4% of the control group. Comparison of the groups showed a significant difference (χ² = 22.67, P < 0.001). CR-MI discrepancy was significantly correlated with Di and Ai in all subjects (P < 0.01).
CONCLUSIONS: There was CR-MI discrepancy in most of the pre-treated patients with signs and symptoms of TMD. This discrepancy may be a contributory factor to the development of TMD in these patients.
I look forward to hearing your comments!
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SDS Instructors
Roy Higson and Andy Lane
SDS Occlusion Blog 
“A positive CR-MI discrepancy, defined as a discrepancy exceeding 1 mm in the vertical or horizontal planes or 0.5 mm in the transverse plane”
What was the rationale of using these papameters to define a discrepancy?
We see symptomatic patients with smaller descrepancies.
Shiraz
I agree, smaller discrepancies can cause more severe symptoms, so it does seem kind of arbitrary, but I suppose they had to draw the line somewhere.
can you elaborate ‘sliding centric occlusion’ a bit more. is it synonymous with CR-CO discrepancy?
I’m not familiar with the term Faisa, what was the context and where have you seen this used?>
it was an assignment for us post-graduate students but i’m unable to find the exact terminology. i wanted to know if slides or shifts or deviations in CR are the same. your article seemed very relevant so i commented.
You have to understand the definitions of CR and MIP first and work from there. CR is defined by the joints, MIP by the teeth – what this article refers to is the potential for harm to the stomatognathic apparatus if there is a discrepancy between the two positions greater than a certain amount. As has already been said, the definition of this as “A positive CR-MI discrepancy, defined as a discrepancy exceeding 1 mm in the vertical or horizontal planes or 0.5 mm in the transverse plane” is somewhat arbitrary and will depend very much on the individual patient under treatment.