title: Influence of Non-Impacted Third Molars on Pathologies of Adjacent Second Molars: A Retrospective Study.
abstract: Although removal of impacted third molars (I-M3s) is common in dental clinics, the decision to retain or remove asymptomatic non-impacted third molars (N-M3s) presents a significant challenge. This study investigates influence of N-M3s on pathologies of adjacent second molars (A-M2s).
  
  
  
  Clinical status of M3s was evaluated, and presence of distal caries, external root resorption (ERR), and alveolar bone loss (ABL) of A-M2s was assessed by orthopantomograms (OPGs). Prevalence of A-M2 pathologies was evaluated and association between N-M3s and pathologies of A-M2s was analyzed by multivariate logistic regression. Significance level was set at 0.05.
  
  
  
  OPGs from 1,958 patients were included in the present study. Among these patients, 45.1% presented with at least one N-M3, and 44.2% of retained M3s were non-impacted. Where N-M3s were present, prevalence of distal caries, ERR, and ABL of A-M2s was 10.0%, 0.8%, and 40.4%, respectively. Although N-M3s did not increase the odds of caries or ERR of A-M2s, presence of N-M3s was associated with 1.77 times higher likelihood of ABL from A-M2s when data were adjusted for age and sex.
  
  
  
  Presence of N-M3s, even if they are asymptomatic, represents an important risk factor for periodontal health of A-M2s. This finding should be considered during clinical decision making regarding retention or extraction of N-M3s, especially when these teeth are non-functional or when their removal will not affect overall occlusal function.
authors.affiliation: Department of Periodontology, National Clinical Research Center for Oral Diseases, School of Stomatology, Fourth Military Medical University, Xi'an, People's Republic of China.|State Key Laboratory of Military Stomatology, School of Stomatology, Fourth Military Medical University.
authors.forename: Zhi-Bang
authors.initials: ZB
authors.lastname: Li
authors.affiliation: Department of Periodontology, National Clinical Research Center for Oral Diseases, School of Stomatology, Fourth Military Medical University, Xi'an, People's Republic of China.|State Key Laboratory of Military Stomatology, School of Stomatology, Fourth Military Medical University.
authors.forename: Hong-Lei
authors.initials: HL
authors.lastname: Qu
authors.affiliation: Department of Periodontology, National Clinical Research Center for Oral Diseases, School of Stomatology, Fourth Military Medical University, Xi'an, People's Republic of China.|State Key Laboratory of Military Stomatology, School of Stomatology, Fourth Military Medical University.
authors.forename: Li-Na
authors.initials: LN
authors.lastname: Zhou
authors.affiliation: Department of Periodontology, National Clinical Research Center for Oral Diseases, School of Stomatology, Fourth Military Medical University, Xi'an, People's Republic of China.|State Key Laboratory of Military Stomatology, School of Stomatology, Fourth Military Medical University.
authors.forename: Bei-Min
authors.initials: BM
authors.lastname: Tian
authors.affiliation: Department of Periodontology, National Clinical Research Center for Oral Diseases, School of Stomatology, Fourth Military Medical University, Xi'an, People's Republic of China.|State Key Laboratory of Military Stomatology, School of Stomatology, Fourth Military Medical University.
authors.forename: Fa-Ming
authors.initials: FM
authors.lastname: Chen
mesh_terms: D000328:Adult; D016301:Alveolar Bone Loss / Q000209:etiology; D003731:Dental Caries / Q000209:etiology; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008963:Molar / Q000000981:diagnostic imaging / Q000473:pathology*; D008964:Molar, Third / Q000473:pathology*; D011862:Radiography, Panoramic; D012189:Retrospective Studies; D012391:Root Resorption / Q000209:etiology; D055815:Young Adult
keywords: Dental caries; molar; molar, third; periodontitis; radiography, panoramic; root resorption