title: The influence of sinus membrane thickness upon membrane perforation during transcrestal sinus lift procedure.
abstract: OBJECTIVE
  Schneiderian membrane perforation is one of the main complications during sinus augmentation. The reasons may be associated with surgical technique, septum, inadequate ridge height, and membrane thickness. However, reports that used cone-beam computed tomography (CBCT) to quantify the thickness of sinus membrane were limited. The aims of this retrospective study were: to study the correlation between membrane thickness and perforation rate during transcrestal sinus lift and to propose a classification system of sinus membrane thickness based upon CBCT data.
  
  
  METHODS
  One hundred and twenty-two subjects who received dental implant restorations over posterior maxilla with a total of 185 transcrestal sinus lift procedures between years 2010 to 2013 were selected consequently. Each patient selected had to have taken CBCT in the initial examination and immediately after surgery. The membrane thickness, perforation rate, residual bone height, and elevated bone height were recorded and processed for statistical analysis.
  
  
  RESULTS
  The mean thickness of the Schneiderian membrane was 1.78 ± 1.99 mm. There was a significant correlation between membrane thickness and perforation rate (P < 0.05), and the perforation rate was higher in thicker (≥3 mm) and thinner membrane (≤0.5 mm). Among the thickness group, Class B (between ≥1 and <2 mm) had the lowest perforation rate. No significant difference was between the perforation and the membrane morphology. A negative relationship between residual bone height and membrane thickness was found. Trend showed that in the thicker and the thinner residual bone height, the higher the perforation rate would be.
  
  
  CONCLUSIONS
  There was a significant correlation between membrane thickness and perforation rate. The perforation rate was lowest when the thickness was 1.5-2 mm.
authors.affiliation: Private Practice, Taipei County, Taiwan, China.
authors.forename: Shih-Cheng
authors.initials: SC
authors.lastname: Wen
authors.affiliation: Department of Dentistry, Cathay General Hospital, Taipei City, Taiwan, China.
authors.forename: Yen-Hua
authors.initials: YH
authors.lastname: Lin
authors.affiliation: Department of Dentistry, Cathay General Hospital, Taipei City, Taiwan, China.
authors.forename: Yeuh-Chao
authors.initials: YC
authors.lastname: Yang
authors.affiliation: Department of Periodontics and Oral Medicine, School of Dentistry, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Hom-Lay
authors.initials: HL
authors.lastname: Wang
mesh_terms: D000328:Adult; D000368:Aged; D054893:Cone-Beam Computed Tomography; D003758:Dental Implantation, Endosseous / Q000009:adverse effects* / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008443:Maxillary Sinus / Q000033:anatomy & histology* / Q000601:surgery*; D008875:Middle Aged; D009297:Nasal Mucosa / Q000033:anatomy & histology* / Q000293:injuries*; D012189:Retrospective Studies
keywords: cone-beam computed tomography; membrane perforation; membrane thickness; sinus lift; transcrestal