Ectopic Eruption of Permanent First Molars
Condition: Failure of Tooth Eruption Associated With Tooth Impaction
MeSH terms: Tooth, Impacted; Cardiac Complexes, Premature; Exanthema
Study type: Observational

Summary: 
      Ectopic eruption may be defined as the eruption of a permanent tooth that takes place in such
      a manner that a partial or a total resorption of the root(s) of an adjacent primary tooth
      occurs and can be noted during routine dental radiographic evaluation. It is a common case in
      mixed dentition and is usually diagnosed by a pediatric dentist. This retrospective study
      aimed to determine the prevalence and related factors of the ectopic eruption of permanent
      first molars(PFM). This retrospective study was performed using the panoramic radiographs of
      11,924 child patients aged 6-10 years with at least one ectopically erupted PFM were
      included. The total prevalence of ectopic eruption, type, age, gender, jaw distribution, and
      bilateral versus unilateral occurrence were determined. The angulation of PFM, mesialization
      ratio of PFM, and degree of adjacent primary second molar(PSM) tooth root resorption were
      also assessed. The chi-square test, ANOVA was used for statistical analysis. A total of 76
      ectopic eruptions were detected in the maxilla, 6 in the mandible, and 2 in both the maxilla
      and the mandible. In terms of the eruption status of cases with ectopic eruption, 27 were
      self-corrected, 51 remained impacted, and 6 were both. The impaction rate of the right upper
      PFMs was higher than that of others. No significant relationship was found between eruption
      status and degree of resorption. As a conclusion, small impaction of the PFM does not mean
      that the PSM lesion is also small. With substantial displacements, a proportionally
      diminutive lesion can exist, and vice versa.
    

Detailed description: 
      Assessment of Angulation The angles between the axes of the PSMs and the long axes of the
      PFMs were measured. The angle was measured using ImageJ application (1.50 n, National
      Institutes of Health, Bethesda, MD, USA). The long axes were formed by a line extending
      parallel to the center of the tooth in an occluso-cervical manner. The vertical angle was
      defined as (-) or (+) according to Sun et al.The angles between the occlusal lines of the
      PSMs and the PFMs were measured. The horizontal angle was defined as (-) or (+) according to
      Sun et al.

      Assessment of PSM Root Resorption The distal root resorption level of the PSM was determined
      using Barberia-Leache et al.'s classification2 as follows; Grade I: mild-limited resorption
      of the cementum or with minimum dentin penetration Grade II: moderate-resorption of the
      dentin without pulp exposition Grade III: severe-resorption of the distal root leading to
      pulp exposure Grade IV: very severe-resorption that affects the mesial root of the PSM.

      Assessment of PFM Mesialization Ratio The mesiodistal size of the PFM and the amount of
      mesialization were measured by the Image J application to evaluate the differences between
      reversible and irreversible ectopic eruption. The mesiodistal size was measured from the
      largest part of the crown, and the amount of mesialization was measured using the distance
      between the drawn tangent on the distal wall of the PSM and the mesial convexity of the PFM.
      Afterwards, the amount of mesialization was proportioned to the mesiodistal size of the PFM.
    

Intervention name(s): Impacted; Self-corrected
Intervention type(s): Diagnostic Test; Diagnostic Test
Intervention description(s): Until an active treatment for the PFM is started or the early exfoliation of PSM occurs, the tooth remains in a self-locking position; The ectopic erupted permanent molar can disregard the self-locking position and continue in a normal direction, but the distal root of the PSM remains more or less a significant atypical resorption
Observational model: Other
Time perspective: Retrospective
Sampling method: Probability Sample
Study population: 
        11,924 child patients aged 6-10 years who attended the Pediatric Dentistry clinics at the
        Faculty of Dentistry, Eskisehir Osmangazi University, between March 2016 and March 2018.
      
Keywords: Ectopic Eruption; Eruption Failure; Impacted Teeth