title: Cuspal movement related to different polymerization protocols.
abstract: OBJECTIVE
  The aim of this study to investigate the effects of different polymerization protocols on the cuspal movement in class II composite restorations.
  
  
  METHODS
  Human premolar teeth were prepared with class II cavities and then restored with composite and three-step and two-step etch-and-rinse adhesive systems under different curing techniques (n = 10). It was used a light- emitting-diode curing unit and the mode of polymerization were: standard (exposure for 40 seconds at 700 mW/cm(2)), pulse-delay (initial exposure for 6 seconds at 350 mW/cm(2) followed by a resting period of 3 minutes and a final exposure of 37 seconds at 700 mW/cm(2)) and soft-start curing (exposure 10 seconds at 350 mW/cm(2) and 35 seconds at 700 mW/cm(2)). The cuspal distance (μm) was measured before and after the restorative procedure and the difference was recorded as cuspal movement. The data were submitted to two-way ANOVA and Bonferroni test (p < 0.05).
  
  
  RESULTS
  The type of adhesive system did not influenced the cuspal movement for all the curing methods. Standard protocol showed the highest values of cuspal movement and was statistically different from the pulse-delay and soft-start curing modes.
  
  
  CONCLUSIONS
  Although the cuspal displacement was not completely avoided, alternative methods of photocuring should be considered to minimize the clinical consequences of composites contraction stress.
authors.affiliation: PhD Student, Department of Restorative Dentistry, São Paulo State University, Araraquara School of Dentistry, Araraquara, São Paulo, Brazil.
authors.forename: Máyra Andressa Rodrigues Valinhos
authors.initials: MA
authors.lastname: Piccioni
authors.affiliation: Titular Professor, Department of Restorative Dentistry, Positivo University Curitiba, PR, Brazil.
authors.forename: Flares
authors.initials: F
authors.lastname: Baratto-Filho
authors.affiliation: Department of Restorative Dentistry, São Paulo State University, Araraquara School of Dentistry, Araraquara, São Paulo, Brazil.
authors.forename: Milton Carlos
authors.initials: MC
authors.lastname: Kuga
authors.affiliation: PhD Student, Department of Restorative Dentistry, Positivo University Curitiba, PR, Brazil.
authors.forename: Eduardo Christiano Caregnatto de
authors.initials: EC
authors.lastname: Morais
authors.affiliation: Assistant Professor, Department of Restorative Dentistry, São Paulo State University, Araraquara School of Dentistry, Araraquara, São Paulo, Brazil.
authors.forename: Edson Alves
authors.initials: EA
authors.lastname: Campos
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D001641:Bicuspid / Q000033:anatomy & histology*; D001696:Biomechanical Phenomena; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry*; D055117:Curing Lights, Dental / Q000145:classification; D003737:Dental Cavity Preparation / Q000145:classification; D003764:Dental Materials / Q000737:chemistry*; D003793:Dental Restoration, Permanent / Q000145:classification*; D006801:Humans; D055115:Light-Curing of Dental Adhesives / Q000295:instrumentation / Q000379:methods*; D008422:Materials Testing; D058105:Polymerization; D011829:Radiation Dosage; D019279:Resin Cements / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013997:Time Factors; D019228:Tooth Crown / Q000033:anatomy & histology*
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D019279:Resin Cements; C084018:Scotchbond Multi-Purpose; C533204:filtek Z350; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate