title: Combined effect of anterior malocclusion and inadequate lip coverage on dental trauma in primary teeth.
abstract: OBJECTIVE
  The main objective of this study was to investigate whether the interaction of malocclusion (open bite or increased overjet) combined with inadequate lip coverage strengthens its association with traumatic dental injury (TDI) in the primary teeth of preschool children compared to the presence of malocclusion alone.
  
  
  METHODS
  A cross-sectional survey was conducted with 376 children aged 36-59 months who attended the National Day of Children's Vaccination. Presence of TDI, tooth discoloration, and sinus tract were evaluated in the children. Variables associated with occlusion were also evaluated. A Poisson regression analysis was performed to verify the association between the explanatory variables and TDI as well as possible interactions among the variables. Then, the prevalence ratio was calculated.
  
  
  RESULTS
  The prevalence of TDI was 27.7%. The maxillary central incisor was the most affected tooth, without differences between the right and left sides. Boys had more dental trauma than girls (P = 0.04). The most common TDI was crown fracture restricted to the enamel (58.4%). Children with a combination of anterior open bite or increased overjet and inadequate lip coverage presented a higher prevalence of TDI than when the malocclusions were presented alone (P < 0.05). The same trends were observed when we included, in the final adjusted model, increased overjet instead of open bite.
  
  
  CONCLUSIONS
  Anterior malocclusions of primary teeth such as increased overjet and anterior open bite are statistically significantly associated with dental trauma only when inadequate lip coverage is also present.
authors.affiliation: São Leopoldo Mandic Institute and Research Center, Rua Jose Rocha Junqueira 13, Ponte Preta, Campinas, São Paulo, Brazil. gabonini@usp.br
authors.forename: Gabriela C
authors.initials: GC
authors.lastname: Bonini
authors.forename: Marcelo
authors.initials: M
authors.lastname: Bönecker
authors.forename: Mariana M
authors.initials: MM
authors.lastname: Braga
authors.forename: Fausto M
authors.initials: FM
authors.lastname: Mendes
mesh_terms: D001938:Brazil / Q000453:epidemiology; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008046:Lip / Q000033:anatomy & histology*; D008297:Male; D008310:Malocclusion / Q000150:complications* / Q000453:epidemiology; D015995:Prevalence; D018677:Tooth Injuries / Q000453:epidemiology / Q000209:etiology*; D014094:Tooth, Deciduous / Q000293:injuries*