Association between maxillary lateral incisors' root volume and palatally displaced canines: An instrumental variables approach to the guidance theory

Root volume measurements of maxillary canines and lateral incisors in patients with unilateral maxillary canine impaction

OBJECTIVE

This study aimed to assess root volumes of maxillary canines and adjacent lateral incisors in patients with unilateral maxillary canine impaction.

METHODS

This cross-sectional study was performed on cone-beam computed tomography (CBCT) scans of 100 patients (49 females and 51 males) with unilateral maxillary canine impaction. The images were loaded in Planmeca Romexis Viewer, and root layers between the cementoenamel junction and apex were reconstructed at 600-µm intervals. At each layer, the root boundary was marked, and finally, the root volume was calculated by multiplying the layers' area by the thickness of 600 µm. The root size of canines and lateral incisors was compared between the impaction and normal eruption sides.

RESULTS

Sixty-two patients showed buccal canine impaction, and 38 presented palatal impaction. The mean root volume of canines on the impaction side was significantly greater than that on the normal eruption side; either the tooth was buccally or palatally impacted (p<0.001). The lateral incisors on the side of buccally-impacted canines showed a significantly smaller root volume than that of the contralateral side (p<0.001). However, there was no significant difference in the root size of lateral incisors between the two sides in cases presenting palatal canine impaction (p=0.177).

CONCLUSION

The difference in root volume of canines between the two sides can serve as an indicator of canine impaction. The reduction in the root size of the lateral incisor on the side of the buccally impacted canine may be due to root resorption created by pressure from the canine's crown.

Influence of the maxillary dimensions and lateral incisor anatomy on the palatal impaction of maxillary permanent canines: A three-dimensional case-control study

OBJECTIVE

The diagnosis of impacted upper permanent canines (IUPC) is a relatively common clinical finding. The aim of this study was to investigate associations between the upper permanent canines palatal impaction, lateral incisors morphology and the maxilla bone base.

MATERIAL AND METHODS

Cone-beam tomography files from 62 subjects were divided into 2 groups: impaction group (ICG/n=31; mean age 14.3±2.4) with 45 canines impacted on the palatal side and age- and sex-matched control group (CG/n=31; mean age 14.3±2.3), with 62 normally erupted canines. Linear and volumetric measurements of the lateral incisors, linear transversal measures and the maxillary anterior perimeter were taken. Independent Student's t-test was used for intergroup analysis with correction of Bonferroni.

RESULTS

Significant differences were found for crown length and root diameter (buccal-palatal) (P<0.005). The maxillary anterior perimeter in the ICG was reduced in relation to the GC but not significantly (P=0.008). The transverse skeletal variables of the maxilla were equivalent in the intergroup comparison (P>0.005).

CONCLUSION

Smaller dimensions in the crown length and in the upper permanent lateral incisors root buccal-palatal diameter were associated with the impaction of upper permanent canines on the palatal side. The maxillary transverse morphology did not show any association with the occurrence of this condition.

Influence of the maxillary dimensions and anterior teeth anatomy on the buccal impaction of upper permanent canines: A three-dimensional case-control study

OBJECTIVE

The diagnosis of impacted upper permanent canines (IUPC) is a relatively common clinical finding. The aim of this study was to investigate the association of the buccal impaction of upper permanent canines with their dimensions and the maxilla bone base.

MATERIAL AND METHODS

Cone beam computed tomography files of 66 patients were allocated into: impaction group (ICG/n=33/mean age 15.7±3.9 years), with 44 impacted canines by the buccal side; control group (CG/n=33/mean age 15.66±3.99 years), matched for age and sex, with 66 canines normally erupted. The following measurements were obtained from ICG and CG groups: linear and volumetric canine dimensions, linear measurements of upper permanent central and lateral incisors, measurements of the anterior perimeter and transverse segments of the maxilla. Independent Student's t-test was used for intergroup analysis with correction of Bonferroni (α=0,005).

RESULTS

Higher values were found in the means of the variables regarding to the anterior teeth crowns in the ICG group, however, without a significant difference (P<0,005). The upper arch anterior perimeter of the individuals with canine impaction through buccal area was reduced compared to CG (P=0.001).

CONCLUSIONS

It can be concluded that individuals with upper buccal impacted permanent canine showed a significantly smaller anterior perimeter of the maxillary arch when compared to the control group. Although greater canine mesiodistal diameter was found in this group, there is no statistical association with the occurrence of this condition.

Nonsurgical Treatment of Class III Malocclusion with Both Anterior and Posterior Crossbites Combined with Impacted and Congenitally Missed Teeth

Class III malocclusions present a great challenge for many orthodontists, especially if malocclusions are found in adult patients and alongside other dental problems. This case report shows an adult patient with a skeletal class III anterior crossbite, a unilateral posterior crossbite on the right side, a congenital absence of both lateral incisors and retained deciduous teeth, and shift in the lower midline. The upper retained deciduous teeth and lower premolars were extracted. Leveling and alignment were initiated. Build-up composite resin placed on the first molars allowed for bite opening. The crossbites were corrected by using sequentially larger archwires combined with class III elastics until both the anterior and posterior crossbites were corrected. The impacted upper right canine was exposed using the closed eruption technique and leveled into the position of the upper lateral incisor. Miniscrews were utilized to close the residual spaces. Both canines were reshaped to simulate the upper lateral incisors. At the end of the treatment, good esthetic and functional results were obtained. In conclusion, orthodontic camouflage can be a viable option for treating patients with multiple skeletal and dental problems.