title: The prevalence and distribution of bone defects in patients with moderate to advanced periodontitis.
abstract: BACKGROUND
  Alveolar bone defect is one of the common features of periodontitis and may vary in its form, extent, and distribution among teeth and individuals. The purpose of this study was to analyze the prevalence and distribution of different forms of bone defects in Taiwanese patients with moderate to advanced periodontitis.
  
  
  METHODS
  One hundred and thirty-seven Taiwanese patients with moderate to advanced periodontitis comprising a total sample of 3542 teeth were studied. During periodontal surgery, osseous defects were explored and classified as interproximal crater, 1-wall, 2-wall, 3-wall, hemiseptal and circumferential defects. Among them, some were also recorded as complicated defects.
  
  
  RESULTS
  Among 3542 existing teeth, 1376 were examined surgically and 483 teeth had bone defects. There was an increase in bone defects from anterior to posterior. The frequencies of defects in anterior and posterior segments were significantly different. More defects were found on the right side than on the left side. Yet there was no difference between the maxillary and mandibular arch. Interproximal surfaces of the first and second molars had the highest prevalence of bone defects. Crater was the most common defect type (26.50%), followed by circumferential (23.40%) and 3-wall defect (20.08%). More than 40% also presented with complicated defects.
  
  
  CONCLUSIONS
  There was an increase in bone defects from anterior to posterior. Interproximal aspects were more frequently involved than buccal or lingual aspects. Crater, circumferential and 3-wall defects were more common than other defect types. The treatment of complicated defects, which comprise over 40% of all defects, presents a challenging task for periodontists.
authors.affiliation: Division of Periodontics, Department of Dentistry, Chang Gung Memorial Hospital, Taipei.
authors.forename: S K
authors.initials: SK
authors.lastname: Wu
authors.forename: H C
authors.initials: HC
authors.lastname: Yeh
authors.forename: C P
authors.initials: CP
authors.lastname: Chan
mesh_terms: D000328:Adult; D000368:Aged; D001842:Bone and Bones / Q000002:abnormalities*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010518:Periodontitis / Q000209:etiology*; D015995:Prevalence; D014071:Tooth Abnormalities / Q000453:epidemiology*