Predictive Factors of Ectopic Eruption of the Maxillary First Permanent Molar

Abstract

In order to provide a diagnostic basis for predicting the possibility of the self-correction of ectopic first permanent molars, differences among normal eruption, reversible and irreversible ectopic eruption of maxillary first permanent molars were retrospectively analyzed. The angles of the long axes and the occlusal lines between the maxillary first permanent molar and the adjacent tooth were measured by panoramic radiographs. The occlusal relationship of second primary molars was also investigated. There is a statistically significant difference between the ectopic eruption group and normal group (p < 0.05), but not between the reversible and irreversible ectopic eruption groups (p > 0.05). The angles between the second primary molar and the first permanent molar, the second primary molar and the second permanent molar in ectopic groups showed a smaller degree than those of the control group. Mesial step was found more frequently in the ectopic eruption group than the normal group. In conclusion, the angulation of the first permanent molar and tooth germ of the maxillary second permanent molar showed close relation with ectopic eruption of the maxillary first permanent molar and ectopic first permanent molar is likely to occur in class Ⅲ patients with maxillary deficiency.

Ectopic eruption of maxillary permanent first molars: Predictive factors for self‐corrected and impacted outcome

“…Based on this study, between the angle of long axis and occlusal line of PFM and PSM was measured using panoramic radiograph 3,8,20 . In this study findings showed that negative vertical angles and mean values was found more in impacted PFM consistent with the results in Sun et al 8 However, the results of this study at negative horizontal angles for impacted PFM were not consistent with previous study 8 . This may be because of the many factors affecting eruption status 7,9,10 and methodological differences with Sun et al study 8 …”

“…Previous studies indicated that increase in negative vertical angle of PFM were significant factors of impacted ectopic eruption of the PFM. Based on this study, between the angle of long axis and occlusal line of PFM and PSM was measured using panoramic radiograph 3,8,20 . In this study findings showed that negative vertical angles and mean values was found more in impacted PFM consistent with the results in Sun et al 8 However, the results of this study at negative horizontal angles for impacted PFM were not consistent with previous study 8 .…”

“…If the diagnosis was conducted without considering the root resorption of the PSM and a number of self‐corrected PFM, the total frequency and bilateralism would be less. Sun et al reported that ectopic eruption occurred 42.6% bilaterally and 57.4% unilaterally 8 . Dabbagh et al found bilateral ectopic eruption in 21 patients and unilateral ectopic eruption in 23 patients , with the right‐sided ectopic eruption being more common than the left‐sided ectopic eruption 18 .…”

“…The vertical and horizontal angle were defined as negative or positive according to Sun et al 8 (Figure 2a‐d).…”

“…The most common ectopic erupted permanent teeth are the maxillary PFMs and canines, followed by the mandibular canines, mandibular second premolars and maxillary lateral incisors 3 . Ectopic PFMs are usually in contact with the distal prominence of the crown of the adjacent PSMs 8 . As a result, ectopic eruption of PFMs may cause many complications, such as impaction of permanent second premolars, pulp obliteration, neuralgic pain, space loss in the dental arch, atypical resorption and premature loss of PSMs 7,9,10 …”