engleski

Mandibular third molars teeth and their influence on late mandibular incisor crowding: longitudinal study

AIM: To investigate the relationship between the presence and dynamics of mandibular third molar development and the occurrence and amount of late mandibular incisor crowding. MATERIALS AND METHOD: Dental plaster casts and panoramic radiographs of 72 subjects (46% female) from the Nittedal growth study, Norway were analysed. The subjects were orthodontically untreated, and recalled for check-up at 12, 15, 18 and 21 years of age. The amount of mandibular incisor crowding was assessed at the ages of 12 and 21 years using the Little index. Dental maturation of the third molars was assessed by the Cameriere index (I3M) at 15, 18 and 21 years. Statistical analyses included a t-test, Pearson correlations, linear and logistic regression. RESULTS: Sixty five subjects had a complete dentition and third molars teeth present until the age of 18. At 18 years 25 per cent of those subjects had their third molars teeth removed. However, there was no change in the amount of the amount of crowding at the age of 21. In 55 subjects, when those with extraction of the third molars were excluded, but those with hypodontia of the third molars were included, differences in the amount of crowding were observed. The amount of crowding was no different between subjects with missing third molars (13%) and those with third molars present. In 47 subjects with a complete dentition and third molars present at the age of 21 years the results demonstrated the change in Little’s index [range –1.78-5.3 mm (mean 0.74 ± 1.41)]. The change in I3M was greater between 15-18 than 18-21 years in both genders (P < 0.001). No linear correlation was found between the amount of crowding and maturation dynamics of the third molars between 15-18, 18-21 and 15-21 years of age. The decelerated development of third molars was a significant predictor of late crowding, producing a ×5.2 higher odds ratio. (95% confidence interval 1.1- 23.6 ; P = 0.034). Gender was not a significant predictor. CONCLUSIONS: No linear relationship between the amount of late lower arch crowding and the dynamics of maturation of third molars was found although a decelerated maturation of the third molars seems to increase the occurrence of crowding.

wisdom teeth ; mandibular ; incisor ; crowding

Inicijalna potpora Sveučilišta u Rijeci 13.06.2.1.53 (Prediktivni čimbenici uspjeha ortodontske terapije u djece i adolescenata)