title: Multifactorial risk assessment for survival of abutments of removable partial dentures based on practice-based longitudinal study.
abstract: OBJECTIVE
  Predicting the tooth survival is such a great challenge for evidence-based dentistry. To prevent further tooth loss of partially edentulous patients, estimation of individualized risk and benefit for each residual tooth is important to the clinical decision-making. While there are several reports indicating a risk of losing the abutment teeth of RPDs, there are no existing reports exploring the cause of abutment loss by multifactorial analysis. The aim of this practice-based longitudinal study was to determine the prognostic factors affecting the survival period of RPD abutments using a multifactorial risk assessment.
  
  
  METHODS
  One hundred and forty-seven patients had been previously provided with a total of 236 new RPDs at the Osaka University Dental Hospital; the 856 abutments for these RPDs were analyzed. Survival of abutment teeth was estimated using the Kaplan-Meier method. Multivariate analysis was conducted by Cox's proportional hazard modelling.
  
  
  RESULTS
  The 5-year survival rates were 86.6% for direct abutments and 93.1% for indirect abutments, compared with 95.8% survival in non-abutment teeth. The multivariate analysis showed that abutment survival was significantly associated with crown-root ratio (hazard ratio (HR): 3.13), root canal treatment (HR: 2.93), pocket depth (HR: 2.51), type of abutments (HR: 2.19) and occlusal support (HR: 1.90).
  
  
  CONCLUSIONS
  From this practice-based longitudinal study, we concluded that RPD abutment teeth are more likely to be lost than other residual teeth. From the multifactorial risk factor assessment, several prognostic factors, such as occlusal support, crown-root ratio, root canal treatment, and pocket depth were suggested.
  
  
  CONCLUSIONS
  These results could be used to estimate the individualized risk for the residual teeth, to predict the prognosis of RPD abutments and to facilitate an evidence-based clinical decision making.
authors.affiliation: Department of Prosthodontics, Gerodontology and Oral Rehabilitation, Osaka University Graduate School of Dentistry, Japan.
authors.forename: Sayaka
authors.initials: S
authors.lastname: Tada
authors.forename: Kazunori
authors.initials: K
authors.lastname: Ikebe
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Matsuda
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Maeda
mesh_terms: D000368:Aged; D002858:Chromium Alloys / Q000737:chemistry; D015331:Cohort Studies; D055812:Community-Based Participatory Research; D000044:Dental Abutments / Q000706:statistics & numerical data*; D016734:Dental Clasps; D003779:Denture Design; D003832:Denture, Partial, Removable / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009811:Odontometry; D010514:Periodontal Pocket / Q000145:classification; D011379:Prognosis; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D018570:Risk Assessment; D012390:Root Canal Therapy / Q000706:statistics & numerical data; D016019:Survival Analysis; D019228:Tooth Crown / Q000033:anatomy & histology; D016388:Tooth Loss / Q000517:prevention & control; D014092:Tooth Root / Q000033:anatomy & histology
chemical_list: D002858:Chromium Alloys
keywords: Abutment; Longitudinal study; Multifactorial risk assessment; Removable partial denture; Survival rate