title: Survival predictions of four types of dental restorative materials.
abstract: The present study assessed the survival predictions made for four different types of dental restorative materials, using a mixture model involving the standard Weibull distribution function. A large number of amalgam, anterior resin, glass polyalkenoate (ionomer) cement, and pit and fissure sealant restorations were examined over varying periods of up to 18 years. The materials had been placed by numerous staff and students at a teaching hospital. Based on maximum likelihood estimations of the parameters of the mixture model distribution, survival curves were generated and found to agree closely with the actuarial survival curves estimated from the same data. As the years of data used to fit the mixture model curves decreased, then the fitted curves started to exhibit obvious divergences from the actuarial curves at 12-13 years for amalgams, 3-4 years for anterior resins and sealants, and 1-2 years for glass polyalkenoate (ionomer) cements. At least 5 per cent of restorations needed to have failed over any period to allow close agreement of the two curves, with the slower failing materials requiring longer observation periods.
authors.affiliation: Department of Dentistry, University of Adelaide, South Australia.
authors.forename: R J
authors.initials: RJ
authors.lastname: Smales
authors.forename: D A
authors.initials: DA
authors.lastname: Webster
authors.forename: P I
authors.initials: PI
authors.lastname: Leppard
mesh_terms: D003188:Composite Resins / Q000737:chemistry*; D003723:Dental Amalgam / Q000737:chemistry*; D003793:Dental Restoration, Permanent / Q000706:statistics & numerical data*; D004868:Equipment Failure; D005899:Glass Ionomer Cements / Q000737:chemistry*; D006801:Humans; D015993:Life Tables; D008422:Materials Testing; D010895:Pit and Fissure Sealants / Q000737:chemistry*; D011336:Probability; D013021:South Australia / Q000453:epidemiology; D013997:Time Factors
chemical_list: D003188:Composite Resins; D005899:Glass Ionomer Cements; D010895:Pit and Fissure Sealants; D003723:Dental Amalgam