Table 4.

Radiographic Evaluation and Prevention of Impaction

Early Radiographic Evaluation	Prevention of Impaction
Ericson S, Kurol J. Eur J Orthod. 1988; 10: 283-95. Three variables visible on panoramic radiographs in mixed dentition period have been proposed: angle, distance and sector.	Ericson S, Kurol J. Eur J Orthod. 1988; 10: 283-95. If the crown of the permanent canine were distal to the midline of the later incisor root, the primary canine extraction normalized the erupting position of the permanent canine in 91% of the cases. In contrast, the success rate decreased to 64% if the permanent canine crown were mesial to the midline of the lateral incisor root.
Lindauer SJ et al. JADA 1992; 123: 91-97. 78% of impacted canines exhibited overlapping with the lateral incisor during the radiographic evaluation in mixed dentition period.	Power SM, Short MB. Br J Orthod 1993; 20: 215-23. Spontaneous canine eruption after primary canine extraction depended on horizontal overlapping with the lateral incisor. If this exceeded half the tooth width, the eruption was unlikely.
Fernandez E et al. Am J Orthod Dentofacial Orthop 1998; 113: 414-20. The overlapping of the canine and lateral incisor in panoramic X-Ray, can be considered as a sign of early canine displacement, after the incisor has completed its root development.	Olive RJ. Aust Orthod J 2002; 18: 64-70. 75% of the canines erupted successfully while in 94% of the cases, the severity of impaction lessened following extraction of the overlying primary canines and orthodontic treatment.
Sambataro S et al. Angle Orthod 2005; 75: 28-34 The closer the canine crowns to the midsagittal plane and the larger the posterior portion of the hemimaxilla, the higher the probability of canine impaction. Olive RJ. Aust Orthod J 2005; 21: 95-101. The sector of impaction was the best guide to the duration of treatment prior to emergence.	Leonardi M et al. Angle Orthod. 2004; 74: 581-6. The extraction of the primary canine as an interceptive treatment measure to prevent palatal canine displacement had a success rate of 50%. The rate of eruption treated by headgear in addition to primary canine extraction was 80%. Baccetti T et al. Eur J Orthod. 2008; 30: 381-5. The removal of primary canine showed a success rate of 62.5%. The rate of canine eruption in patients treated with the addition of headgear was 87.5%. Baccetti T et al. Am J Orthod Dentofacial Orthop 2009; 136: 657-61. The prevalence rate of canine eruption after rapid maxillary expansion was (65.7%).