Radial plane tooth position and bone wall dimensions in the anterior maxilla: A CBCT classification for immediate implant placement

J Prosthet Dent. 2018 Jul;120(1):50-56. doi: 10.1016/j.prosdent.2017.09.005. Epub 2017 Nov 29.


Statement of problem: The biological and esthetic challenge of the post-extraction ridge is relevant to restorative implant dentistry, most significantly in the anterior esthetic zone. Previous authors have discussed facial bone wall dimensions and classified their variations. A reclassification may be pertinent.

Purpose: The purpose of this observational, clinical study was to introduce a new classification system for anterior maxilla tooth position with guidelines for immediate implant placement. Data for facial and palatal bone wall height and thickness are also presented.

Material and methods: Maxillary anterior teeth (n=591) were analyzed as viewed in the radial plane of cone beam computed tomography (CBCT) scans from 150 patients. Each tooth was classified according to its position and inclination within its alveolus (class I, middle of the alveolus; IA, thick facial bone; IB, thin facial bone; class II, retroclined; IIA, thick crestal bone; IIB, thin crestal bone; class III, proclined; class IV, facially outside bone envelope; class V, both thin facial and palatal bone with apical isthmus). Bone thickness was measured for both facial and palatal walls at the following points: crestal (A), mid-root (B), apex (C), and 4 mm beyond the apex. Bone wall height was also evaluated.

Results: A thin facial bone wall predominated (≤1 mm) at the crest (83%) and the mid-root point (92%). Most palatal walls were thin (<1 mm) at the crest (63%) and thick (≥2 mm) at the mid-root point (98%) and apex (99%). Class I tooth position accounted for 6.1%, class II for 76.5%, class III for 9.5%, class IV for 7.3%, and class V for 0.7%.

Conclusions: Maxillary anterior teeth have predominantly thin facial bones, making palatal bone thickness a crucial variable. The new classification system for radial plane tooth position is a pragmatic clinical analysis for immediate implant treatment planning.

Publication types

  • Observational Study

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Alveolar Process / diagnostic imaging*
  • Cone-Beam Computed Tomography / methods*
  • Female
  • Humans
  • Immediate Dental Implant Loading / methods*
  • Male
  • Maxilla / diagnostic imaging*
  • Maxilla / surgery*
  • Middle Aged