Asymmetry of the mandibular condyle in Haida Indians

Abstract

The condyles of 72 aged and sexed Haida Indians were measured for anteroposterior and mediolateral diameter and their approximate areas calculated. Dental wear was assessed for the same individuals. Asymmetry of condyle size did not appear to change with age. In a pair-wise analysis, no relationship was found between the largest of a pair of condyles and the most worn side of the dentition. The difference in size between each pair of condyles (normalized for individual size) was plotted as a histogram and found to have a normal distribution with a mean of 0 and no skewness. Condyle asymmetry does not appear to be related to differential chewing forces but more closely fits the model of fluctuating asymmetry.

The condylar asymmetry measurements in different skeletal patterns

“…In the present study, the mean asymmetry index for the class II group was 3·94%, and the mean asymmetry index for the class I group was 4·42%. Our findings are not discussed with previously investigated parameters, because of differences in age and groupings of our subjects (Costa, 1986; Habets et al ., 1988; Miller et al ., 1994; Miller & Smidt, 1996; Miller & Bodner, 1997).…”

“…Malocclusions have been sited as a factor in the development of TMD (Lieberman et al ., 1985; Piller et al ., 1992; Henrikson et al ., 1997). The aetiology of TMD is thought to be multifactorial, with muscle hyperactivity believed to be an important factor; stress, parafunction, arthrogenous factor and condylar asymmetry also feature (Williamson, 1977; Costa, 1986; Laat et al ., 1986; Årtun et al ., 1992; Miller, 1992, 1997; Miller et al ., 1994).…”

“…also investigated tee condylar asymmetry index. Condylar asymmetry, that is the comparison of vertical condylar height (CH) between right and left mandibular condyles, has been used to validate clinical tests of diagnostic categories in patient with TMD (Costa, 1986; Miller et al ., 1994; Miller, 1997). Some authors (Miller & Smidt, 1996; Miller & Bodner, 1997) have suggested the value of condylar asymmetry measurements in patients with TMD, Angle's class II division 2 and class III malocclusions.…”

The Orthopantomogram®, an aid in diagnosis of temporomandibular joint problems.

“…At least two hypotheses have been generated to explain mandibular asymmetry. The first one is that observed asymmetries are simple facts of fluctuating morphological asymmetry (Costa, 1986). The second is a functional and mechanical one.…”

Lower face asymmetry as a marker for developmental instability

“…Fluctuating asymmetries (FA) are randomly distributed deviations that occur equally likely on the left or the right side of the face (Waddington, ). FAs have been documented for dental cusp traits (Khraisat et al, ), calcium content of teeth (Siegel & Mooney, ), mesio‐distal or bucco‐lingual tooth sizes (Khalaf, Elcock, Smith, & Brook, ), and mandibular condyle shape (Costa, ). FAs have been suggested to be the result of early‐life stress such as protein deprivation, weaning trauma, heavy metal exposure, obesity and smoking (Corruccini, Handler, Mutaw, & Lange, ; Doyle & Johnston, ; Doyle, Kelley, & Siegel, ; Graham, Roe, & West, ; Harris & Nweeia, ; Kieser, ; Kieser, Groeneveld, & Da Silva, ; Kohn & Bennett, ; Mooney, Siegel, & Gest, ; Siegel & Doyle, ).…”