title: Determination of implant position for immediate implant placement in maxillary central incisors using palatal soft tissue landmarks.
abstract: OBJECTIVE
  The aim of this study was to suggest a clinical guideline to properly position immediate implant placement in the anterior maxillary area.
  
  
  METHODS
  The computed tomography (CT) records of 250 patients (125 males, 125 females; mean age 49.5 years) were evaluated, and the relationship of the sagittal root positions of the maxillary central incisor teeth to their respective alveolar bony housing was classified as buccal (B), medial (M), or palatal (P). Then, the clinical guideline was suggested based on the implications derived from the classification. In the second investigation, the validity of the clinical guideline was confirmed by CT analysis. First, a reference line was defined using soft tissue landmarks. Then, a virtual rectangle representing the dental implant was created and merged on the CT image, symbolizing the space where the dental implant would be positioned. The rectangular frame was positioned on the image in accordance with the guideline. The frame on the image was thoroughly assessed to detect the possibility of perforation of the labial plate. The location of the initial drilling access on the respective crown was determined by extending the longitudinal axis of the frame in a coronal direction.
  
  
  RESULTS
  Of the 250 samples, 94.0% were classified as type B. Type M and P represented 5.6% and 0.4% of the samples, respectively. In 82.0% of the samples, the frame was safely positioned, not contacting the labial or palatal cortical plate in the alveolar bony housing. Moreover, when a frame representing a tapered implant form with an apical diameter of 3.5 mm was applied, 98.8% of samples were positioned safely in the alveolar bony housing. The longitudinal axis of the frame crossed the respective crown at the incisal tip in 54.4% of the cases. It crossed the labial side of the crown and cingulum of the crown in 42.0% and 3.6% of the cases, respectively.
  
  
  CONCLUSIONS
  The root of the maxillary central incisor teeth tended to be positioning labially in the alveolar bony housing. The result of the CT analysis confirms the clinical guideline as a dependable clinical reference in immediate implant placement.
authors.forename: Shin-Hye
authors.initials: SH
authors.lastname: Chung
authors.forename: Young-Seok
authors.initials: YS
authors.lastname: Park
authors.forename: Seung-Hwan
authors.initials: SH
authors.lastname: Chung
authors.forename: Won-Jun
authors.initials: WJ
authors.lastname: Shon
mesh_terms: D000328:Adult; D000368:Aged; D059925:Anatomic Landmarks / Q000000981:diagnostic imaging*; D003442:Crowns; D000044:Dental Abutments; D003758:Dental Implantation, Endosseous; D015921:Dental Implants; D019250:Dental Implants, Single-Tooth; D005260:Female; D006801:Humans; D057893:Immediate Dental Implant Loading; D007180:Incisor / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D008297:Male; D008437:Maxilla / Q000000981:diagnostic imaging*; D008875:Middle Aged; D010160:Palate, Soft / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D011859:Radiography; D014082:Tooth Fractures / Q000000981:diagnostic imaging; D014092:Tooth Root / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D055815:Young Adult
chemical_list: D015921:Dental Implants