title: Comparison of linear and zero-inflated negative binomial regression models for appraisal of risk factors associated with dental caries.
abstract: BACKGROUND
  Dental caries among children has been described as a pandemic disease with a multifactorial nature. Various sociodemographic factors and oral hygiene practices are commonly tested for their influence on dental caries. In recent years, a recent statistical model that allows for covariate adjustment has been developed and is commonly referred zero-inflated negative binomial (ZINB) models.
  
  
  OBJECTIVE
  To compare the fit of the two models, the conventional linear regression (LR) model and ZINB model to assess the risk factors associated with dental caries.
  
  
  METHODS
  A cross-sectional survey was conducted on 1138 12-year-old school children in Moradabad Town, Uttar Pradesh during months of February-August 2014. Selected participants were interviewed using a questionnaire. Dental caries was assessed by recording decayed, missing, or filled teeth (DMFT) index.
  
  
  METHODS
  To assess the risk factor associated with dental caries in children, two approaches have been applied - LR model and ZINB model.
  
  
  RESULTS
  The prevalence of caries-free subjects was 24.1%, and mean DMFT was 3.4 ± 1.8. In LR model, all the variables were statistically significant. Whereas in ZINB model, negative binomial part showed place of residence, father's education level, tooth brushing frequency, and dental visit statistically significant implying that the degree of being caries-free (DMFT = 0) increases for group of children who are living in urban, whose father is university pass out, who brushes twice a day and if have ever visited a dentist.
  
  
  CONCLUSIONS
  The current study report that the LR model is a poorly fitted model and may lead to spurious conclusions whereas ZINB model has shown better goodness of fit (Akaike information criterion values - LR: 3.94; ZINB: 2.39) and can be preferred if high variance and number of an excess of zeroes are present.
authors.forename: Manu
authors.initials: M
authors.lastname: Batra
authors.affiliation: Department of Public Health Dentistry, Government Dental College and Hospital, Srinagar, India.
authors.forename: Aasim Farooq
authors.initials: AF
authors.lastname: Shah
authors.forename: Prashant
authors.initials: P
authors.lastname: Rajput
authors.forename: Ishrat Aasim
authors.initials: IA
authors.lastname: Shah
mesh_terms: D002648:Child; D003430:Cross-Sectional Studies; D004245:DMF Index; D003731:Dental Caries / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D006801:Humans; D007194:India / Q000453:epidemiology; D016014:Linear Models; D008297:Male; D015995:Prevalence; D012044:Regression Analysis; D018570:Risk Assessment; D012307:Risk Factors