Archive for the ‘Research’ Category

Playing with Vertical Dimension? Know the Rules!

October 9, 2011 1 comment

There’s a great position paper on the subject of when, how and by how much it is OK to change the Vertical Dimension of Occlusion (VDO) from M. Rebibo et al of the Université de la Méditerranée, Marseille HERE

There is a discussion of the myths around whether one can or cannot increase or decrease VDO and a very useful chart (Table 2) showing the effect that a change in height at the molars will have on position of the incisors and the incisal pin of the articulator. There are also several very interesting case presentations, including the use of occlusal equilibration alone to close down a significant anterior open bite. Please read the article and comment below if you have any questions of observations.

I might put a few similar cases of my own up if there’s sufficient interest, or if you have some photos and a case report you are prepared to share and have discussed please send them to me and I will publish them on here for you.


Correlation between a CR:MIP discrepancy and TMD research published

January 24, 2011 6 comments

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.


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!

Occlusion and Cervical Lesions – great article by Gary Unterbrink

August 3, 2010 2 comments

The latest copy of the online magazine Apex features a great article by Dr Gary Unterbrink (of Lichtenstein) on the aetiology of non-carious cervical lesions, sometimes known as “abfraction” lesions.

As many of you will know, this is a controversial area with many opposing camps, but Gary dissects the evidence and comes up with an elegant explanation, supported by a large number of references.

I’m happy to say this fits in with what we have always taught at SDS, but he puts it across so well I have now decided to make this article required reading for our delegates. Accordingly, I hope to include this article in the 4th module of the Introduction to Occlusion Part 1 distance learning package, so our delegates will see this as part of an understanding of the role of clenching and bruxism in the aetiology of what we like to call “occlusal disease”.

I’ll be interested to know what you think, so please post your comments here.

The excellent Apex ezine is well worth subscribing to HERE

Does FEAR adversely affect dentists’ clinical decisions?

June 7, 2010 1 comment

When I posed this question on the GDPUK site we got a very surprising result – 60% of dentists who replied experienced fear EVERY DAY that they admitted affected their clinical decision making, and only 14% NEVER let their fears get in the way of making a proper decision. A sad indictment, and unintended result, of our increasing litigious and over-regulated society.

I submitted this question to the Shirley Glasstone Hughes Trust web site

and the question came out “top of the pops” for May, which meant it went for Evidence Review by Chris Fox of Peninsula Dental School.
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