title: The resection angle in apical surgery: a CBCT assessment.
abstract: OBJECTIVE
  The primary objective of the present radiographic study was to analyse the resection angle in apical surgery and its correlation with treatment outcome, type of treated tooth, surgical depth and level of root-end filling.
  
  
  METHODS
  In the context of a prospective clinical study, cone beam computed tomography (CBCT) scans were taken before and 1 year after apical surgery to measure the angle of the resection plane relative to the longitudinal axis of the root. Further, the surgical depth (distance from the buccal cortex to the most lingual/palatal point of the resection plane) as well as the level of the root-end filling relative to the most coronal point of the cut root face was determined. Treated teeth were categorized into four groups (maxillary and mandibular anterior and posterior teeth). The final material comprised 62 treated roots in 55 teeth.
  
  
  RESULTS
  The mean calculated resection angle of all roots was 17.7° ± 11.4° (range -9.6° to 43.4°). Anterior maxillary roots presented the highest mean angle (25.8° ± 10.3°) that was significantly different from the mean angle in posterior maxillary roots (10.7° ± 9.4°; p < 0.001) and from the mean angle in posterior mandibular roots (15.1 ± 9.8°; p < 0.05). In roots with a shallow resection angle (≤20°), the rate of healed cases was higher than in roots with an acute resection angle (>20°), however without reaching statistical significance (p = 0.0905). Angles did not correlate either with the surgical depth or with the retrofilling length.
  
  
  CONCLUSIONS
  Statistically significant differences were observed comparing resection angles of different tooth groups. However, the angle had no significant effect on treatment outcome.
  
  
  CONCLUSIONS
  Contrary to common belief, the resection angle in maxillary anterior teeth was greater than in the other teeth. The surgeon is advised to pay attention to the resection angle when bevelling maxillary anterior teeth in apical surgery.
authors.affiliation: Department of Oral Surgery and Stomatology, School of Dental Medicine, University of Bern, Freiburgstrasse 7, CH-3010, Bern, Switzerland. thomas.vonarx@zmk.unibe.ch.
authors.forename: Thomas
authors.initials: T
authors.lastname: von Arx
authors.affiliation: Department of Oral Surgery and Stomatology, School of Dental Medicine, University of Bern, Freiburgstrasse 7, CH-3010, Bern, Switzerland.
authors.forename: Simone F M
authors.initials: SF
authors.lastname: Janner
authors.affiliation: Department of Oral Surgery and Stomatology, School of Dental Medicine, University of Bern, Freiburgstrasse 7, CH-3010, Bern, Switzerland.|Department of Oral and Maxillofacial Surgery, Copenhagen University Hospital, Copenhagen, Denmark.
authors.forename: Simon S
authors.initials: SS
authors.lastname: Jensen
authors.affiliation: Department of Oral Surgery and Stomatology, School of Dental Medicine, University of Bern, Freiburgstrasse 7, CH-3010, Bern, Switzerland.
authors.forename: Michael M
authors.initials: MM
authors.lastname: Bornstein
mesh_terms: D000328:Adult; D000368:Aged; D001047:Apicoectomy / Q000379:methods*; D054893:Cone-Beam Computed Tomography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014092:Tooth Root / Q000000981:diagnostic imaging* / Q000601:surgery*; D016896:Treatment Outcome
keywords: Apical surgery; Cone beam computed tomography; Resection angle; Root-end resection