title: Cone-beam computed tomographic analysis of sinus membrane thickness, ostium patency, and residual ridge heights in the posterior maxilla: implications for sinus floor elevation.
abstract: OBJECTIVE
  To determine, using cone-beam computed tomography (CBCT), the residual ridge height (RRH), sinus floor membrane thickness (MT), and ostium patency (OP) in patients being evaluated for implant placement in the posterior maxilla.
  
  
  METHODS
  CBCT scans of 128 patients (199 sinuses) with ≥1 missing teeth in the posterior maxilla were examined. RRH and MT corresponding to each edentulous site were measured. MT >2 mm was considered pathological and categorized by degree of thickening (2-5, 5-10 mm, and >10 mm). Mucosal appearance was classified as "normal", "flat thickening", or "polypoid thickening", and OP was classified as "patent" or "obstructed". Descriptive and bivariate statistical analyses were performed.
  
  
  RESULTS
  MT >2 mm was observed in 60.6% patients and 53.6% sinuses. Flat and polypoid mucosal thickening had a prevalence of 38.1% and 15.5%, respectively. RRH ≤4 mm was observed in 46.9% and 48.9% of edentulous first and second molar sites, respectively. Ostium obstruction was observed in 13.1% sinuses and was associated with MT of 2-5 mm (6.7%), 5-10 mm (24%), and >10 mm (35.3%, P < 0.001). Polypoid mucosal lesions were more frequently associated with ostium obstruction than flat thickenings (26.7% vs. 17.6%, P < 0.001).
  
  
  CONCLUSIONS
  Thickened sinus membranes (>2 mm) and reduced residual ridge heights (≤4 mm) were highly prevalent in this sample of patients with missing posterior maxillary teeth. Membrane thickening >5 mm, especially of a polypoid type, is associated with an increased risk for ostium obstruction. In the presence of these findings, an ENT referral may be beneficial prior to implant-related sinus floor elevation.
authors.affiliation: Private Practice, Mumbai, India.
authors.forename: Siddharth
authors.initials: S
authors.lastname: Shanbhag
authors.forename: Prabodh
authors.initials: P
authors.lastname: Karnik
authors.forename: Prashant
authors.initials: P
authors.lastname: Shirke
authors.forename: Vivek
authors.initials: V
authors.lastname: Shanbhag
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000539:Alveolar Process / Q000000981:diagnostic imaging*; D054893:Cone-Beam Computed Tomography; D015921:Dental Implants; D005260:Female; D006801:Humans; D007576:Jaw, Edentulous, Partially / Q000000981:diagnostic imaging / Q000534:rehabilitation; D008297:Male; D008443:Maxillary Sinus / Q000000981:diagnostic imaging*; D008875:Middle Aged; D011857:Radiographic Image Interpretation, Computer-Assisted; D059546:Sinus Floor Augmentation
chemical_list: D015921:Dental Implants
keywords: cone-beam computed tomography; maxillary sinus; membrane thickness; sinus floor elevation