title: An up to 3-year randomized clinical study comparing indirect and direct resin composites used to restore worn posterior teeth.
abstract: OBJECTIVE
  To compare a developmental indirect resin composite with an established, microfilled directly placed resin composite used to restore severely worn teeth. The cause of the tooth wear was a combination of erosion and attrition.
  
  
  METHODS
  Over a 3-year period, a total of 32 paired direct or indirect microfilled resin composite restorations were placed on premolars and molars in 16 patients (mean age: 43 years, range: 25 to 62) with severe tooth wear. A further 26 pairs of resin composite were placed in 13 controls (mean age: 39 years, range 28 to 65) without evidence of tooth wear. The material was randomly selected for placement in the left or right sides of the mouth.
  
  
  RESULTS
  Sixteen restorations were retained in the tooth wear group (7 indirect and 9 direct), 7 (22%) fractured (4 indirect and 3 direct), and 9 (28%) were completely lost (5 indirect and 4 direct). There was no statistically significant difference in failure rates between the materials in this group. The control group had 21 restorations (80%) that were retained (10 indirect and 12 direct), a significantly lower rate of failure than in the tooth wear patients (P = .027).
  
  
  CONCLUSIONS
  The results of this short-term study suggest that the use of direct and indirect resin composites for restoring worn posterior teeth is contraindicated.
authors.affiliation: Department of Prosthodontics, Floor 25, King's College London Dental Institute, Guy's Tower, London Bridge SE1 9RT, London, United Kingdom. David.bartlett@kcl.ac.uk
authors.forename: David
authors.initials: D
authors.lastname: Bartlett
authors.forename: Geeta
authors.initials: G
authors.lastname: Sundaram
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D000328:Adult; D000368:Aged; D001641:Bicuspid / Q000473:pathology; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding; D003764:Dental Materials / Q000737:chemistry*; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent / Q000145:classification / Q000379:methods*; D006801:Humans; D008875:Middle Aged; D008963:Molar / Q000473:pathology; D011140:Polyurethanes / Q000737:chemistry; D019217:Tooth Attrition / Q000628:therapy*; D014077:Tooth Erosion / Q000628:therapy*
chemical_list: D000180:Acrylic Resins; D003188:Composite Resins; D003764:Dental Materials; C513708:Heliomolar; D011140:Polyurethanes