title: Sagittal occlusal relationships and asymmetry in prematurely born children.
abstract: The aim of this investigation was to examine the effect of pre-term birth on sagittal occlusal relationships. The subjects were 328 prematurely born white and black children and 1804 control children who participated in the cross-sectional study of the Collaborative Perinatal Project (USA) in the early 1960s and 1970s. Dental examinations, including dental casts and photographs, were performed at the age of 6-12 years. The sagittal occlusion of the permanent molars and the canine relationship was recorded by examining and measuring the hard stone casts. The pre-term and comparison groups were divided by sex and race. A significantly greater prevalence of pre-normal canine relationships was found in the pre-term group than in the controls (P < 0.001). The incidence of a bilateral symmetrical canine relationship was 60.3 per cent in both the pre-term and control groups, but in the pre-term group the girls had better symmetry than the boys. Asymmetry occurred significantly more often on the left side (P < 0.001), especially in the control boys, but this was not so clear in the pre-term group. The prevalence of mesial molar occlusion was greater in the pre-term group. These results suggest that premature birth and the consequent exceptional adaptation from intra- to extra-uterine nutrition may influence dental occlusal development. This emphasizes the importance of early functional activity and differences in masticatory muscle activity and the largely unknown phenomenon of early catch-up growth. Individual differences in neonatal factors, in the need for intubation and other medical care are also of importance. Pre-term birth may also interfere with the development of symmetry and lateralization.
authors.affiliation: Department of Oral Development and Orthodontics, Institute of Dentistry, University of Oulu, Finland.
authors.forename: Virpi
authors.initials: V
authors.lastname: Harila-Kaera
authors.forename: Mathias
authors.initials: M
authors.lastname: Grön
authors.forename: Tuomo
authors.initials: T
authors.lastname: Heikkinen
authors.forename: Lassi
authors.initials: L
authors.lastname: Alvesalo
mesh_terms: D044383:Black People; D002508:Cephalometry; D016009:Chi-Square Distribution; D002648:Child; D016001:Confidence Intervals; D003430:Cross-Sectional Studies; D003481:Cuspid / Q000473:pathology; D003766:Dental Occlusion; D005146:Facial Asymmetry / Q000209:etiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000254:growth & development*; D008137:Longitudinal Studies; D008297:Male; D008310:Malocclusion / Q000209:etiology*; D008410:Masticatory Muscles / Q000254:growth & development; D008445:Maxillofacial Development; D003765:Models, Dental; D008963:Molar / Q000473:pathology; D015588:Observer Variation; D010781:Photography; D015203:Reproducibility of Results; D012737:Sex Factors; D044465:White People