title: Fracture resistance of maxillary premolars restored with direct and indirect adhesive techniques.
abstract: OBJECTIVE
  To evaluate the fracture resistance of teeth restored using 2 intracoronal direct and indirect adhesive techniques.
  
  
  METHODS
  Forty maxillary premolars were divided randomly into 4 groups of 10: group 1, intact teeth; group 2, mesio-occlusodistal (MOD) cavity preparation associated with endodontic therapy (unrestored); group 3, MOD cavity preparation and restoration with direct composite resin (Z100, 3M ESPE); and group 4, MOD cavity preparation and restoration with indirect ceramic inlay (IPS Empress, Ivoclar-Vivadent). Specimens were subsequently submitted to an axial compression test, using an 8-mm diameter steel ball at a loading speed of 0.5 mm per minute, until their fracture.
  
  
  RESULTS
  The average compression force causing cuspal fracture in the 4 experimental groups was group 1, 138.4 kg; group 2, 49.0 kg; group 3, 105.4 kg; and group 4, 82.7 kg. ANOVA analysis and Tukey tests showed that cavity preparation significantly weakened the remaining tooth structure. The fracture resistance of teeth restored using direct composite resin was not significantly different from that of teeth restored with ceramic inlays (p > 0.05). None of the materials tested was able to restore completely the fracture resistance lost during cavity preparation.
  
  
  CONCLUSIONS
  Cavity preparation significantly weakens the remaining tooth structure. Direct and indirect intracoronal adhesive restorations can partly restore fracture resistance of teeth weakened by wide cavity preparation.
authors.affiliation: Department of Operative Dentistry, Federal University of Bahia School of Dentistry, BA, Brazil. jace@ufba.fr
authors.forename: Maria Jacinta M Coelho
authors.initials: MJ
authors.lastname: Santos
authors.forename: Rebeca Barroso
authors.initials: RB
authors.lastname: Bezerra
mesh_terms: D000538:Aluminum Silicates; D000704:Analysis of Variance; D001641:Bicuspid; D003188:Composite Resins; D019245:Compressive Strength; D001840:Dental Bonding; D003737:Dental Cavity Preparation / Q000009:adverse effects; D003776:Dental Porcelain; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent / Q000379:methods*; D003799:Dental Stress Analysis; D006801:Humans; D007284:Inlays; D008437:Maxilla; D012822:Silicon Dioxide; D018709:Statistics, Nonparametric; D014082:Tooth Fractures / Q000209:etiology / Q000517:prevention & control*; D015040:Zirconium
chemical_list: D000538:Aluminum Silicates; D003188:Composite Resins; C075815:IPS-Empress ceramic; C083568:Z100 composite resin; D003776:Dental Porcelain; D012822:Silicon Dioxide; D015040:Zirconium