Associations between displaced maxillary canines and tooth agenesis: a cross-sectional radiographic study in a large sample.

AIM: The aims of the present study were to: investigate prevalence, characteristics, sex distribution and significant associations with DMC in a group of growing subjects affected by tooth agenesis; analyze whether the severity of the tooth agenesis has an effect on dental development and presence of DMC, and evaluate whether hypodontia can be a factor involved in maxillary canine impaction when isolated in the maxilla or in the mandible.

MATERIALS: The study group (SG) was composed of 336 subjects (167 Females, 169 Males) with a mean age of 10.7 ± 1.2 years, presenting with at least one missing tooth. Exclusion criteria included syndromes, craniofacial malformations (e.g., cleft lip/palate), extractions and trauma history and previous orthodontic treatment. The SG was divided into 3 subgroups according to agenesis severity: mild agenesis with 1-2 absent teeth, moderate agenesis with 3-5 absent teeth and, severe agenesis with 6 or more absent teeth. The CG consisted of 336 subjects (167 females, 169 males) with a mean age of 10.7 ± 1.2 years, without agenesis. Stepwise multiple logistic regression using the backwards elimination and the Wald (W) test method was performed to identify the best combination of hypodontia and DMC (P<0.05).

RESULTS: The most represented category in SG consisted in mild agenesis (86.9%); moderate and severe agenesis groups respectively represented the 11.7% and 1.4% of SG. Significant association between the agenesis severity and prevalence of DMC was not assessed. Agenesis was diagnosed in both arches in 46 subjects. Maxillary hypodontia and mandibular hypodontia was respectively detected in 156 and 134 subjects. The most frequent missing teeth were mandibular second premolars (45.8%), lateral incisors (41.7%) and maxillary second premolars (17.8%). A significant correlation between agenesis and DMC was observed in the SG (P<0.05). Only the agenesis of maxillary lateral incisors remained in the final model during backward stepwise deletion. Significant association between the severity of dental agenesis and prevalence of DMC was not assessed.

CONCLUSIONS: The outcomes revealed no difference related to the severity of dental agenesis and prevalence of DMC. Only the agenesis of maxillary lateral incisors should be considered directly connected with DMC.




Key words: Hypodontia, displaced maxillary canine, panoramic radiograph, guidance theory.

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