title: An Analysis of the Proximity of Maxillary Posterior Teeth to the Maxillary Sinus Using Cone-beam Computed Tomography.
abstract: BACKGROUND
  It is known that the level of the maxillary sinus floor varies with age. Because few studies have investigated whether the position of the posterior roots relative to the maxillary sinus varied with the variation of the sinus floor or not, the present study assessed the position according to age.
  
  
  METHODS
  Cone-beam computed tomographic images of 848 patients were reconstructed to evaluate the position of the posterior roots relative to the sinus floor, which were divided into 3 types, and quantify the distances between posterior root apexes and the adjacent border of the sinus floor. Measurements were taken for each root, and data were correlated with age, which was divided into 4 groups (≤20 years, 21-40 years, 41-60 years, and >60 years).
  
  
  RESULTS
  A total of 3063 premolars and 3095 molars were evaluated. The mean distances from the root tips to the border of the maxillary sinus floor increased with increasing age. From the first and second premolar roots, the mean distances ranged from 3.6 ± 4.1 mm to 8.9 ± 4.6 mm and from 0.7 ± 3.3 mm to 5.3 ± 3.9 mm, respectively. From the mesiobuccal, distobuccal, and palatinal roots of the first molars, the mean distances were -0.4 ± 2.8 mm to 4.6 ± 4.0 mm, -0.3 ± 2.4 mm to 4.4 ± 3.8 mm, and -0.4 ± 3.5 mm to 3.9 ± 4.1 mm, respectively. From the mesiobuccal, distobuccal, and palatinal roots of the second molars, the mean distances were -0.5 ± 2.2 mm to 3.4 ± 3.5 mm, 0.3 ± 2.2 mm to 3.9 ± 3.7 mm, and 1.1 ± 3.2 mm to 4.6 ± 4.5 mm, respectively. The frequency of type IS decreased with increasing age. It was very low in first premolars (0%-8.13%) and higher in second premolars (0%-25.68%), first molars (0%-44.75%), and second molars (0%-32.89%). Age significantly influenced the mean distances to the sinus floor and the frequencies of type IS (inside).
  
  
  CONCLUSIONS
  Cone-beam computed tomographic imaging is an effective method to study the position of the posterior roots to the maxillary sinus floor. Variation in proximity measurements was found by age, with those under the age of 40 showing a greater likelihood of the position of maxillary roots above/inside the sinus floor.
authors.affiliation: Department of Prosthodontics, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China.
authors.forename: Xiao-Mei
authors.initials: XM
authors.lastname: Tian
authors.affiliation: Department of Prosthodontics, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Qian
authors.affiliation: Department of Prosthodontics, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China.
authors.forename: Xian-Zhen
authors.initials: XZ
authors.lastname: Xin
authors.affiliation: Stomatology Special Consultation Clinic, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China. Electronic address: weibin0328@hotmail.com.
authors.forename: Bin
authors.initials: B
authors.lastname: Wei
authors.affiliation: Department of Orthodontics, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China. Electronic address: gongyao0328@hotmail.com.
authors.forename: Yao
authors.initials: Y
authors.lastname: Gong
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001641:Bicuspid / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D054893:Cone-Beam Computed Tomography / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008437:Maxilla / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D008443:Maxillary Sinus / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D008875:Middle Aged; D008963:Molar / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D019227:Tooth Apex / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D014092:Tooth Root / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D055815:Young Adult
keywords: Cone-beam computed tomography; maxillary premolar; maxillary sinus; molar