title: Analysis of factors associated with cracked teeth.
abstract: BACKGROUND
  The purpose of this study was to analyze the characteristics, distribution, and associated factors of longitudinal fractured teeth according to the well-defined criteria of the American Association of Endodontists (AAE).
  
  
  METHODS
  One hundred seven teeth with longitudinal fracture from 103 patients were diagnosed and analyzed. The patients' signs, symptoms, age, and sex were noted as well as the tooth number, dental arch, filling materials, size/classification of restoration, crack direction, pulp vitality, whether the patient had undergone endodontic treatment, bite test results, percussion test results, wear facet, and periodontal pocket depth.
  
  
  RESULTS
  Eighty-seven teeth were diagnosed with a cracked tooth (81.3%), 14 were diagnosed with vertical root fracture (VRF, 13.1%), 4 had a split tooth (3.7%), and 2 had a fractured cusp (1.9%); 82.2% showed a sensitive reaction on the bite test. Longitudinal tooth fractures were observed most frequently in patient in their 40s. The upper first molar (28.0%) was most frequently cracked, followed by the lower first molar (25.2%), the lower second molar (20.6%), and the upper second molar (16.8%). Most longitudinal tooth fractures (72.0%) occurred mainly in restored teeth, whereas only 28.0% were found in intact teeth. Compared with resin (4.7%) or porcelain (0.9%), the use of nonbonded inlay restoration materials such as gold (20.5%) or amalgam (18.7%) increased the occurrence of longitudinal tooth fractures. Out of 107 of longitudinal fractured teeth, 33 (30.8%) were treated endodontically and 74 (69.2%) were not. VRF was associated with endodontic treatment.
  
  
  CONCLUSIONS
  The bite test is most reliable for reproducing symptoms. The combined use of various examination methods is recommended for detecting cracks and minutely inspecting all directions of a tooth.
authors.affiliation: Department of Conservative Dentistry and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea.
authors.forename: Deog-Gyu
authors.initials: DG
authors.lastname: Seo
authors.forename: Young-Ah
authors.initials: YA
authors.lastname: Yi
authors.forename: Su-Jung
authors.initials: SJ
authors.lastname: Shin
authors.forename: Jeong-Won
authors.initials: JW
authors.lastname: Park
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D001641:Bicuspid / Q000293:injuries; D003188:Composite Resins / Q000737:chemistry; D003387:Cracked Tooth Syndrome / Q000145:classification / Q000175:diagnosis*; D003442:Crowns; D003723:Dental Amalgam / Q000737:chemistry; D003743:Dental Enamel / Q000293:injuries; D003764:Dental Materials / Q000737:chemistry; D003776:Dental Porcelain / Q000737:chemistry; D003791:Dental Pulp Test; D003793:Dental Restoration, Permanent / Q000145:classification; D005260:Female; D005500:Follow-Up Studies; D006047:Gold Alloys / Q000737:chemistry; D006801:Humans; D007284:Inlays; D008297:Male; D008875:Middle Aged; D008963:Molar / Q000293:injuries; D010514:Periodontal Pocket / Q000175:diagnosis; D012390:Root Canal Therapy; D012737:Sex Factors; D019228:Tooth Crown / Q000293:injuries; D014082:Tooth Fractures / Q000145:classification / Q000175:diagnosis*; D014092:Tooth Root / Q000293:injuries; D057085:Tooth Wear / Q000175:diagnosis
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D006047:Gold Alloys; D003776:Dental Porcelain; D003723:Dental Amalgam