Damage to the primary dentition resulting from thumb and finger (digit) sucking.

It is estimated that approximately 50 percent of infants at one year of age suck a thumb or finger. The number decreases rapidly by ages four to five years. The average age for spontaneous cessation of the habit is 3.8 years of age. Anterior open bite is the most frequent malocclusion reported with digit sucking. In this study the authors investigated the influence of thumb and finger-sucking in the anterior and posterior sections of the primary dentition in three age-groups: three, four, and five years. The study population included 930 subjects. Data for the non-oral-habit group were compared with the data for the thumb and/ or finger-sucking group. At all ages the frequencies of open-bite and maxillary protrusion for the thumb and finger-sucking group were higher than the non-oral-habit group. The frequencies did not appear age-related. There appeared to be an increased tendency to a permanent malocclusion in children who continued after four years of age.