Effects of digit sucking on dental arch dimensions in the primary dentition.

The purpose of this study was to assess the effects of the duration and type of digit sucking habits (thumb or finger) on the dental arch dimensions of children with digit sucking habit; and compare the findings with children without the habit. A cross-sectional sucking behaviour data was collected on 250 school children aged 3 to 5 years using questionnaires completed by parents. Dental arch parameters including arch widths and arch depths were measured directly from the models obtained from the children and compared using t-test and ANOVA. The results indicated reduced maxillary arch widths (P < 0.001), increased maxillary arch depths (P = 0.009), reduced mandibular canine arch depth (P = 0.004) in those with digit sucking habits compared with the controls. Thumb sucking showed a significant reduction in intercanine widths and mandibular molar arch depth when compared with finger sucking. There was no statistically significant association between duration of digit habits and changes in dental arch depths. In addition, some changes in the dental arch parameters persisted well beyond the cessation of the digit habit. The results suggest a need for recommendations for discontinuing these habits that will be optimal in preventing digit sucking related malocclusion.