title: Primary tooth wear in functional lateralities.
abstract: OBJECTIVE
  The purpose of this study was to explore the sidedness of primary tooth horizontal wear facets between the left and right sides of the dentition among 2 types of functionally lateralized (hand, foot, eye) children--those who were true right-sided (TRS), and partially or totally nonright-sided (NRS) at 4 years of age.
  
  
  METHODS
  Study subjects were 855 children with signs of wear in deciduous teeth on the dental casts (N=1,720) of the GOS (Genetic Odontometric Study of the Collaborative Perinatal) project, carried out in the 1960s in the United States by the National Institute of Neurological Disorders and Stroke (NINDS) in a cross-sectional manner at a mean age of 8(1/2) years (40% Caucasian and 60% African-American children). The statistical method used was chi-square analysis.
  
  
  RESULTS
  Tooth wear was identified from dental casts in approximately 50% of cases. Wear was symmetric (equal on the right and left) in 49% of these dentitions, while asymmetric wear was found in 50%. Left-sided extra wear was slightly more common (26%) than right-sided extra wear (24%), but gender and race differences appeared. Statistically significant unilateral wear was found among TRS Caucasian boys on the dentition's right side. In NRS Caucasian boys, however, the left-sided extra wear was more common than for the right-sided extra wear (P=.04). In Caucasian girls, the same relationship appeared, but the difference was not significant (P=.11). In African American TRS children, the left-sided extra wear was more common, and symmetric proportion was increased in boys. The differences between laterality and gender groups, however, were not statistically significant.
  
  
  CONCLUSIONS
  Sidedness in the form and function of a primary dental apparatus has variation among gender and race groups that is involved with the determination of general structural and functional lateralities. Early asymmetric oral functioning (unilateral bolus placement, sucking, chewing, bruxism, etc) should be considered in registration of the various phases of occlusal development, also having craniofacial aspects due to asymmetric growth promoting function.
authors.affiliation: Department of Oral Development and Orthodontics, Institute of Dentistry, University of Oulu, Finland. tpth@sun3.oulu.fi
authors.forename: Tuomo
authors.initials: T
authors.lastname: Heikkinen
authors.forename: Jaana
authors.initials: J
authors.lastname: Rusanen
authors.forename: Virpi
authors.initials: V
authors.lastname: Harila
authors.forename: Lassi
authors.initials: L
authors.lastname: Alvesalo