title: Early prediction of mandibular third molar eruption/impaction using linear and angular measurements on digital panoramic radiography: A radiographic study.
abstract: BACKGROUND
  The impaction rate is higher for the third molars than for any other tooth in modern human population. This study was conducted with the aim to evaluate the validity of linear and angular measurements on the digital panoramic radiograph as a reference for early prediction of mandibular third molar eruption/impaction.
  
  
  METHODS
  Digital panoramic radiographs of 200 subjects were selected based on their status of eruption of mandibular third molars; fully erupted (Group A), partially erupted (Group B), fully developed but not erupted (Group C) and partially developed groups (Group D). Each group comprised 50 subjects with 25 males and 25 females. Nine variables (linear measurements, angles, and ratios) were determined and measured bilaterally by two observers and values were compared between the study groups and genders.
  
  
  RESULTS
  The data thus obtained were analyzed for comparison among all the study groups. It was found that the difference in the mean values of lower eruption space (LES) measurements, α-angle (angle between long axis of the third molar and gonial-symphyseal plane) and β-angle (angle between long axis of mandibular second and third molars) were significant (P < 0.05). The mean values of mesiodistal width, LES-ramus, LES-Xi point and β-angle were found more in males than in females. No significant difference was observed between the sides.
  
  
  CONCLUSIONS
  α- and β-angle together with LES measurements give the accurate information on early prediction of lower third molar eruption or impaction.
authors.affiliation: Department of Oral Medicine and Radiology, D.J. College of Dental Sciences and Research, Modinagar, Uttar Pradesh, India.
authors.forename: Rachninder
authors.initials: R
authors.lastname: Kaur
authors.affiliation: Department of Oral Medicine and Radiology, Vananchal Dental College and Hospital, Ranchi, Jharkhand, India.
authors.forename: Anand C
authors.initials: AC
authors.lastname: Kumar
authors.affiliation: Department of Oral Medicine and Radiology, Faculty of Dentistry, SEGi University, Kota Damansara, Selangor, Malaysia.
authors.forename: Ranjana
authors.initials: R
authors.lastname: Garg
authors.affiliation: Department of Oral Medicine and Radiology, D.J. College of Dental Sciences and Research, Modinagar, Uttar Pradesh, India.
authors.forename: Sugandha
authors.initials: S
authors.lastname: Sharma
authors.affiliation: Department of Oral Medicine and Radiology, D.J. College of Dental Sciences and Research, Modinagar, Uttar Pradesh, India.
authors.forename: Trisha
authors.initials: T
authors.lastname: Rastogi
authors.affiliation: Department of Periodontics, Faculty of Dentistry, SEGi University, Kota Damansara, Selangor, Malaysia.
authors.forename: Vivek Vijay
authors.initials: VV
authors.lastname: Gupta
keywords: Impacted mandibular third molar; linear and angular measurements; panoramic radiography