Unilateral Angle II in functional lateralities.
The aim of this study was to explore unilateral Angle II-type malocclusion prevalences in functionally true right-sided (TRS) and non-right-sided (NRS) children having one or more left-sided functions (eye, hand, foot). A half cusp sagittal relationship of the upper and lower M1 and Dm2 was determined on dental casts of 1423 young American black and white children in a cross-sectional sample with the mean age of 8.5 years (range 6-12 years). Hand, foot and eye preferences were recorded at the age of 4 years during the Collaborative Perinatal Study. The prevalences of symmetric bilateral Angle I and II and asymmetric unilateral Angle II right and Angle II left cases were compared between TRS and NRS children using Chi-square analysis. In general, unilateral Angle II right occurred in 9 per cent of the population and Angle II left in 6.5 per cent. In moderate non-right sideness (two-thirds of left dominant functions), these proportions were 17 and 3 per cent, respectively, and in true right sidedness 8 and 6 per cent, respectively. TRS subjects were more symmetric (bilateral Angle I or II in 85 per cent of cases) than NRS children (80 per cent), and the differences were statistically significant (P < 0.02). These results highlight the anatomical relationships of structures supporting the occlusion and the symmetry/asymmetry of the neurocranium, cranial base, masticatory apparatus, and probably also the sidedness and the growth-stimulating effect of lateralized jaw function. Based on the results and considering earlier observations on brain asymmetry in functional lateralities, it can be hypothesized that a normal symmetric sagittal occlusal relationship is based on unilateral sagittal compensatory growth to maintain optimal bite, challenging early preventive orthodontic treatment in suspect unilateral Angle II cases.
Department of Oral Development and Orthodontics, Institute of Dentistry, University of Oulu, Finland.
T
T
Heikkinen
T
T
Poikela
M
M
Grön
L
L
Alvesalo
D044383:Black People; D016009:Chi-Square Distribution; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004292:Dominance, Cerebral / Q000502:physiology*; D023882:Dominance, Ocular / Q000502:physiology; D005146:Facial Asymmetry / Q000145:classification* / Q000473:pathology; D005260:Female; D005528:Foot / Q000502:physiology; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D008311:Malocclusion, Angle Class I / Q000145:classification / Q000473:pathology; D008312:Malocclusion, Angle Class II / Q000145:classification* / Q000473:pathology; D012886:Skull / Q000473:pathology; D014481:United States; D044465:White People; D001741:Black or African American