title: Clinical longevity of extensive direct composite restorations in amalgam replacement: up to 3.5 years follow-up.
abstract: OBJECTIVE
  This prospective clinical trial evaluated the longevity of direct resin composite (DRC) restorations made on stained dentin that is exposed upon removal of existing amalgam restorations in extensive cavities with severely reduced macro-mechanical retention for amalgam replacement.
  
  
  METHODS
  Between January 2007 and September 2013, a total of 88 patients (57 women, 31 men; mean age: 51.6 years old) received extensive cusp replacing DRCs (n=118) in the posterior teeth. DRCs were indicated for replacement of existing amalgam restorations where dentin substrates were stained by amalgam. After employing a three-step total-etch adhesive technique (Quadrant Unibond Primer, Quadrant Unibond Sealer, Cavex), cavities were restored using a hybrid composite (Clearfil Photo Posterior, Kuraray). At baseline and thereafter every 6 months, restorations were checked upon macroscopically visible loss of anatomical contour, marginal discolouration, secondary caries, fractures, debonding and endodontic problems. Restorations were scored as failed if any operative intervention was indicated for repair, partial or total replacement.
  
  
  RESULTS
  Restorations were observed for a minimum of seven, and maximum 96 months (mean: 40.3 months). In total, four failures were observed due to fracture (n=1), endodontic complications (n=2) and inadequate proximal contact (n=1). Failures were related neither to inadequate adhesion nor to secondary caries. Cumulative survival rate was 96.6% (95% CI: 89-95) up to a mean observation time of 40.3 months (Kaplan-Meier) with an annual failure rate of 0.9%.
  
  
  CONCLUSIONS
  In case of amalgam replacement, dentin that is exposed upon removal of existing amalgam restorations does not impair clinical longevity of extended cusp replacing direct resin composite restorations.
  
  
  CONCLUSIONS
  Extensive amalgam restorations can be replaced with a variety of treatment options. This clinical study indicates that in such cases directly applied resin based composites offer a reliable and low-cost treatment option, even if dentin is stained by amalgam corrosion products.
authors.affiliation: Rijksuniversiteit Groningen, University Medical Center, Center for Dentistry and Oral Hygiene, Department of Fixed and Removable Prosthodontics, Groningen, The Netherlands. Electronic address: hans.scholtanus@gmail.com.
authors.forename: Johannes D
authors.initials: JD
authors.lastname: Scholtanus
authors.affiliation: University of Zurich, Dental Materials Unit, Center for Dental and Oral Medicine, Clinic for Fixed and Removable Prosthodontics and Dental Materials Science, Zurich, Switzerland.
authors.forename: Mutlu
authors.initials: M
authors.lastname: Ozcan
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D003116:Color; D003188:Composite Resins / Q000737:chemistry*; D003723:Dental Amalgam / Q000737:chemistry*; D001840:Dental Bonding / Q000379:methods; D003731:Dental Caries / Q000209:etiology; D003737:Dental Cavity Preparation / Q000379:methods; D018772:Dental Marginal Adaptation; D003764:Dental Materials / Q000737:chemistry*; D017268:Dental Prosthesis Retention; D003788:Dental Pulp Diseases / Q000145:classification; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent / Q000379:methods* / Q000592:standards; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D019233:Retreatment; D013499:Surface Properties; D016019:Survival Analysis; D014075:Tooth Discoloration / Q000628:therapy; D016896:Treatment Outcome
chemical_list: D003188:Composite Resins; D003764:Dental Materials; C092420:Clearfil Photo Posterior; D003723:Dental Amalgam
keywords: Adhesive dentistry; Amalgam; Clinical study; Cusp replacement; Direct composite restorations; Minimal invasive dentistry