title: Influence of cavity type and size of composite restorations on cuspal flexure.
abstract: OBJECTIVE
  The present study examines the influence of cavity type, and size of composite restorations on cuspal flexure due to polymerization shrinkage.
  
  
  METHODS
  Thirty healthy premolars were selected and divided into two experimental groups. Group 1: Mesial, mesio-distal, and MOD cavities were successively prepared in each tooth by means of the SONICSYS approx system (KaVo) using a n 2 (small) diamond tip. Group 2: The same cavity preparation sequence was followed but a n 3 (medium) tip was used. Cavity preparations were performed and afterwards restored using the same adhesive system and resin composite. Cuspal displacement was measured 15 min after completion of each type of restoration.
  
  
  RESULTS
  Under the experimental conditions used, polymerization shrinkage of composite restorations resulted in an inward deflection of the cusps in all the situations evaluated. The Friedman global test found significant differences according to the cavity type and size (p<0.05). The Wilcoxon test revealed that deflection was significantly affected by the amount of dental tissue lost, since practically no movement was observed in the case of mesial cavities but extensive displacements were recorded for MOD restorations (p<0.05). However, no influence of bucco-lingual width on cuspal flexure was detected by the Student s t test (p>0.05).
  
  
  CONCLUSIONS
  The present study demonstrates that significantly higher cuspal deflection is observed in MOD restorations, showing that the degree of dental removal influences the cuspal flexure from polymerization shrinkage of composite restorations.
authors.affiliation: Facultad de Odontología, Universidad de Granada, Granada, España. sglopez@ugr.es
authors.forename: Santiago
authors.initials: S
authors.lastname: González López
authors.forename: Maria Victoria
authors.initials: MV
authors.lastname: Sanz Chinesta
authors.forename: Laura
authors.initials: L
authors.lastname: Ceballos García
authors.forename: Francisco
authors.initials: F
authors.lastname: de Haro Gasquet
authors.forename: Maria Paloma
authors.initials: MP
authors.lastname: González Rodríguez
mesh_terms: D003188:Composite Resins; D003731:Dental Caries / Q000473:pathology* / Q000628:therapy*; D006801:Humans
chemical_list: D003188:Composite Resins