title: A wide mesio-distal gap in sites of congenitally missing maxillary lateral incisors is related to a thin alveolar ridge.
abstract: OBJECTIVE
  To evaluate (i) a possible correlation between the mesio-distal gap width and the alveolar ridge (AR) dimensions in patients missing the maxillary lateral incisor (I2) either due to agenesis or loss and (ii) the possibility of straightforward implant placement based on simulation.
  
  
  METHODS
  The bucco-palatal width, area, and height of the AR at the position of I2, and the mesio-distal gap width between the central incisor and the canine, were assessed in maxillary CT scans of three groups: Patients with (i) agenesis of I2 (TA; n = 40); (ii) I2 regularly erupted but extracted (TL; n = 24); (iii) I2 regularly erupted and in situ (C; n = 40). Further, the possibility of straightforward placement of an implant 3 or 3.5 mm in diameter ×10 mm in length, with 1 mm distance from the buccal and palatal plate of the alveolar ridge was simulated and compared to the actual treatment delivered.
  
  
  RESULTS
  Bucco-palatal width and area of the AR at I2 and the adjacent teeth was significantly reduced in TAcompared to TLand C. Further, in TA, but not TL, an increasing mesio-distal gap width between the central incisor and canine resulted in a significantly reduced bucco-palatal width of the edentulous AR. This impeded a simulated straightforward implant placement in >50% of the cases in TA, even with a reduced implant diameter.
  
  
  CONCLUSIONS
  In patients congenitally missing I2, an increased mesio-distal gap width correlates significantly with reduced edentulous AR dimensions. A mesio-distal gap of >6 mm was associated with thin bucco-palatal alveolar ridges, precluding straightforward implant placement in 60-80% of the cases.
authors.affiliation: Department of Periodontology, Faculty of Odontology, University of Malmö, Malmö, Sweden.|Division of Oral Surgery, University Clinic of Dentistry, Medical University of Vienna, Vienna, Austria.
authors.forename: Kristina
authors.initials: K
authors.lastname: Bertl
authors.affiliation: Division of Oral Surgery, University Clinic of Dentistry, Medical University of Vienna, Vienna, Austria.
authors.forename: Verena Schulze
authors.initials: VS
authors.lastname: Grotthoff
authors.affiliation: Division of Orthodontics, University Clinic of Dentistry, Medical University of Vienna, Vienna, Austria.
authors.forename: Michael H
authors.initials: MH
authors.lastname: Bertl
authors.affiliation: Karl Donath Laboratory for Hard Tissue and Biomaterial Research, Division of Oral Surgery, Medical University of Vienna, Vienna, Austria.|Austrian Cluster for Tissue Regeneration, Vienna, Austria.|Ludwig Boltzmann Institute for Clinical and Experimental Traumatology, Vienna, Austria.
authors.forename: Patrick
authors.initials: P
authors.lastname: Heimel
authors.affiliation: Department of Diagnostic Radiology, Division of Osteoradiology, General Hospital, Medical University of Vienna, Vienna, Austria.
authors.forename: André
authors.initials: A
authors.lastname: Gahleitner
authors.affiliation: Division of Oral Surgery, University Clinic of Dentistry, Medical University of Vienna, Vienna, Austria.
authors.forename: Christian
authors.initials: C
authors.lastname: Ulm
authors.affiliation: Department of Periodontology, Faculty of Odontology, University of Malmö, Malmö, Sweden.
authors.forename: Andreas
authors.identifier: http://orcid.org/0000-0001-8161-3754
authors.initials: A
authors.lastname: Stavropoulos
mesh_terms: D000539:Alveolar Process / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D007180:Incisor / Q000002:abnormalities*; D008297:Male; D008437:Maxilla; D011861:Radiography, Dental; D012189:Retrospective Studies; D016388:Tooth Loss / Q000209:etiology*; D055815:Young Adult
keywords: agenesis; alveolar ridge; dental implant; lateral incisor; maxilla; tooth loss