Marginal adaptation of composite restorations photoactivated by LED, plasma arc, and QTH light using low-modulus resin liners.
OBJECTIVE
The aim of this study was to evaluate the influence of resin liners on the marginal adaptation to dentin of resin composite restorations photoactivated by a conventional quartz-tungsten halogen lamp (QTH), light emitting diodes (LED), and a plasma arc light (PAC).


METHODS
The buccal surfaces of 120 bovine incisors were ground until a flat dentin area was obtained. A circular cavity (4 mm in diameter x 1.5 mm in depth) was prepared in this area. Scotchbond Multi Purpose was applied in the cavities following the manufacturer's instructions. The specimens were randomly assigned into 4 groups according to the lining technique: (1) control (1 adhesive layer); (2) three adhesive layers; (3) Filtek Flow; (4) Protect Liner F. Each group was further divided into 3 subgroups according to the light-curing method: (A) QTH; (B) LED; (C) PAC. All cavities were then restored with a single increment of Filtek Z250 restorative composite and polished. Caries Detector was applied to each specimen for 5 s. Images of dye-stained gaps were observed under a stereomicroscope and transferred to a computer measurement program. Gap values were obtained by dividing the dyed margin length by the total cavity length, then multiplying by 100. Data were analyzed using ANOVA and Tukey's test (p < 0.05).


RESULTS
All the tested lining techniques significantly decreased marginal gap formation when compared with the control group only for the QTH light groups. There was no significant difference among the light-curing methods.


CONCLUSIONS
The use of resin liners can effectively reduce the gap formation along dentin margins, but only when QTH light is used.
Alonso
Roberta Caroline Bruschi
RC
Department of Restorative Dentistry, Dental Materials Area, Piracicaba Dental School, UNICAMP, Piracicaba, São Paulo, Brazil. robalonso@fop.unicamp.br
Cunha
Leonardo Gonçalves
LG
Correr
Gisele Maria
GM
Puppin-Rontani
Regina Maria
RM
Correr-Sobrinho
Lourenço
L
Sinhoreti
Mário Alexandre Coelho
MA
D000180:Acrylic Resins / Q000737:chemistry* / Q000528:radiation effects; D000818:Animals; D002417:Cattle; D003188:Composite Resins / Q000737:chemistry* / Q000528:radiation effects; D003736:Dental Cavity Lining; D018772:Dental Marginal Adaptation; D003804:Dentin / Q000737:chemistry; D011140:Polyurethanes / Q000737:chemistry* / Q000528:radiation effects; D011897:Random Allocation
D000180:Acrylic Resins; C029012:Composite Dental Resin; D003188:Composite Resins; D011140:Polyurethanes