title: Cavity preparation and influence of restorative materials on the prevention of secondary caries.
abstract: OBJECTIVE
  This in vitro study evaluated the influence of cavity preparation using the Er:YAG laser and restorative materials containing fluoride on preventing caries lesions.
  
  
  BACKGROUND
  It has been suggested that cavity preparation using the Er:YAG laser has a potential for improving resistance to secondary caries on enamel.
  
  
  METHODS
  Forty unerupted human third molars teeth were sectioned into 72 blocks of dental enamel and distributed into two groups to prepare cavities measuring (1.6 mm diameter) with diamond burs (DB) or Er:YAG laser (LA; 6 Hz, 300 mJ, 47 J/cm(2)). After that, each group was divided into three subgroups and restored with a glass-ionomer cement (GI), a resin-modified glass-ionomer (RM), or a composite resin (CR). Blocks were thermal cycled and submitted to a pH challenge to develop artificial caries-like lesions. Lesions were evaluated by Knoop microhardness test. An average of four indentations was used. Statistical analyses were performed by ANOVA followed by Tukey's test.
  
  
  RESULTS
  The results (in Knoop hardness number) for DB cavity preparation were GI, 235.5 (+/-75.5); RM, 137.1 (+/-64.1); and CR, 39.3 (+/-26.5). For LA cavity preparation, the results were GI, 410.0 (+/-129.7); RM, 310.3 (+/-119.5); and CR, 96.4 (+/-57.4).
  
  
  CONCLUSIONS
  There was less development of caries lesion around LA-prepared cavities than around the DB-prepared cavities; however, no synergistic cariostatic effect was observed between the Er:YAG laser and glass ionomer cement.
authors.affiliation: Dental Research and Graduate Studies, Division Department of Restorative Dentistry, Guarulhos University, Guarulhos, SP, Brazil.
authors.forename: Mario Alberto Marcondes
authors.initials: MA
authors.lastname: Perito
authors.forename: Ana Carolina Tedesco
authors.initials: AC
authors.lastname: Jorge
authors.forename: Patrícia Moreira
authors.initials: PM
authors.lastname: de Freitas
authors.forename: Alessandra
authors.initials: A
authors.lastname: Cassoni
authors.forename: José Augusto
authors.initials: JA
authors.lastname: Rodrigues
mesh_terms: D003731:Dental Caries / Q000517:prevention & control*; D003737:Dental Cavity Preparation / Q000379:methods*; D003738:Dental Cements / Q000627:therapeutic use*; D003793:Dental Restoration, Permanent / Q000379:methods; D006801:Humans; D053685:Laser Therapy; D053844:Lasers, Solid-State
chemical_list: D003738:Dental Cements