title: A clinical evaluation of posterior composite resin restorations: 8-year findings.
abstract: OBJECTIVE
  From a continuing investigation of the clinical performance of three different types of composite resin, the findings of the clinical evaluation at 8 years are presented.
  
  
  METHODS
  One operator placed 330 restorations in Class I and Class II preparations in the posterior teeth of 72 patients. Every patient received at least one restoration of each type of material: a microfilled composite, a small particle hybrid, a relatively coarse particle hybrid, and an amalgam control. Restorations were evaluated using clinical criteria.
  
  
  RESULTS
  Forty six patients attended the 8-year recall. Twenty-five of the 213 restorations (13.7% of the composites and 5.8% of the amalgams) originally placed in these 46 patients had previously failed or been lost from the study or were assessed as requiring replacement at the 8-year recall. Bulk fracture and secondary caries at the margin were the most common forms of failure in the composite restorations. Other failures or losses were associated with a non-margin defect in the composite, caries not associated with the restoration, pulpal considerations, extraction for orthodontics and reasons unknown. One-hundred and ninety-three restorations (including five that required replacement) were available for clinical evaluation at 8 years and these included 17 Class II restorations. Significantly fewer restorations placed with the coarse particle hybrid exhibited evidence of marginal deterioration.
  
  
  CONCLUSIONS
  At 8 years, composite restorations in posterior teeth had failed at a rate two to three times that of amalgam restorations. The most common types of failure were bulk fracture and secondary caries at the margin.
authors.affiliation: Department of Clinical Dentistry, Westmead Hospital Dental Clinical School, NSW, Australia.
authors.forename: C J
authors.initials: CJ
authors.lastname: Collins
authors.forename: R W
authors.initials: RW
authors.lastname: Bryant
authors.forename: K L
authors.initials: KL
authors.lastname: Hodge
mesh_terms: D000293:Adolescent; D000328:Adult; D001641:Bicuspid; D003188:Composite Resins / Q000009:adverse effects / Q000737:chemistry / Q000145:classification; D003723:Dental Amalgam / Q000737:chemistry; D003731:Dental Caries / Q000209:etiology; D003737:Dental Cavity Preparation / Q000145:classification; D018772:Dental Marginal Adaptation; D003788:Dental Pulp Diseases / Q000209:etiology; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent / Q000009:adverse effects / Q000145:classification; D005069:Evaluation Studies as Topic; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008963:Molar; D019233:Retreatment; D013499:Surface Properties; D014081:Tooth Extraction
chemical_list: D003188:Composite Resins; D003723:Dental Amalgam