Effect of digit-sucking habits on root morphology in primary incisors.

The purpose of this paper is to determine if digit sucking causes root resorption on primary central incisors. Randomly selected dental records of 98 patients, ages two to four years, were exam/ned. The presence or absence of a digit habit, as determined from the history, was compared to anterior occlusal radiographs for evidence of root resorption on maxillary primary central incisors. The threeand fouryear-old age groups contained 39 and 37 subjects, respectively. The digit habit patients had 86% of the atypical resorptions in the three-year-old group and 84% in the four-year-old group. Fifty-nine per cent of patients with habits demonstrated unusual resorptive patterns, compared with 8% of those without habits. The association between atypical resorptive patterns and the presence of digit habits was significant in both groups and when the groups were comb/ned (p .0005). The presence of digit sucking appears to contribute to atypical resorptive patterns on maxillary primary central incisors. Digit sucking is one of several oral habits which have garnered attention among health professionals for many years, particularly because of the harmful effects upon the dentition and supporting structures. There is little doubt that digit sucking can result in malocclusion if the intensity, duration, and frequency of the habit are pronounced. Popovich and Thompson, in a study involving 1,258 children, found that there was a significant association between the incidence of Class II malocclusions and persistent digit sucking. ~ It also appears that digit habits can create strong anterior forces on the maxillary arch, causing more anteriorly positioned maxillae in sucking than in nonsucking groups. 2 Furthermore, children with digit habits tend to have increased frequencies of posterior crossbite. 3 No studies have been done which fully examine the effect of digit habits on the morphology of the tooth root. It is well established as part of orthodontic theory that excessive orthodontic forces, in terms of duration and amount, will cause external root resorption. 4 Therefore, if a digit habit is of sufficient intensity, duration, and frequency, it is reasonable to speculate that root resorption might occur. The rationale for this study is that an increased frequency of digit habits demonstrates a circumferential or semilunar root resorption on the primary central incisors. The purpose of this paper is to investigate any such effect.