Influence of adhesive systems on interfacial dentin gap formation in vitro.
OBJECTIVE
This study measured: 1) the interfacial dentin gap formation (IGW) of 2 etch & rinse and 3 self-etch systems with different degrees of acidity and determined the correlation between the smear layer thickness and interfacial gap formation after 1 day and 6 months water storage; 2) the hybrid layer thickness (HLT) produced by the adhesives applied under different smear layer thicknesses.


METHODS
Three self-etch adhesives, a mild (Clearfil SE Bond; SE), a moderate (Optibond Solo Plus Self-Etch Primer; SO) and a strong (Tyrian Self Priming Etchant + One Step Plus; TY), and 2 etch & rinse systems (Single Bond; SB and Scotchbond Multi-Purpose Plus; SBMP) were studied. After flat grinding of the occlusal surfaces, 30 molars were sectioned longitudinally in 2 halves. Dentin surfaces with thick and thin smear layers were obtained for each tooth after polishing different sections on 60- and 600-grit SiC paper, respectively. A resin composite (Z250) build-up was made on each tooth section after randomized application of the adhesives. After 24-hour storage in water, resin-dentin bonded sticks (0.8 mm2) were prepared and divided for 1-day and 6-month measurements. The IGW was measured in a stereomicroscope under 400x. SEM micrographs were also made in order to measure the HLT provided by each adhesive.


RESULTS
The thickness of the smear layer did not influence the mean gap width (p>0.05). The etch & rinse systems showed the lowest mean IGW in the 1-day group. Their IGW remained unchanged after 6 months. The self-etch systems showed wider initial IGW, which diminished after 6 months water storage, to sizes similar to the etch & rinse systems. The hybrid layer was thicker when bonded to #60 SiC-treated dentin; however, this difference was only statistically different for the 3-step etch & rinse system (p=0.001). The thickest hybrid layers were observed for the 2 etch & rinse adhesive systems and the thinnest for the mild self-etch. A negative and strong correlation between IGW and HLT was observed for the self-etching adhesive systems tested (r=80.2, p=0.01).
Loguercio
Alessandro Dourado
AD
Universidade do Oeste de Santa Catarina, Joaçaba, Brazil. aloguercio@hotmail.com
Reis
Alessandra
A
Bortoli
Giana
G
Patzlaft
Rafael
R
Kenshima
Silvia
S
Rodrigues Filho
Leonardo Elóy
LE
Accorinte
Maria de Lourdes Rodrigues
Mde L
van Dijken
Jan W V
JW
D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D017554:Carbon Compounds, Inorganic / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D019279:Resin Cements / Q000737:chemistry; D017655:Silicon Compounds / Q000737:chemistry; D016369:Smear Layer; D013499:Surface Properties; D013997:Time Factors; D014867:Water / Q000737:chemistry
C103506:Bis-GMA, BPDM, HEMA dental-bonding resin; D017554:Carbon Compounds, Inorganic; C438313:Clearfil SE Bond; D003188:Composite Resins; D017220:Dentin-Bonding Agents; C444701:Filtek Z250; D008689:Methacrylates; C451600:OptiBond Solo Plus; D019279:Resin Cements; C425844:Scotchbond Multi-Purpose Plus; D017655:Silicon Compounds; C481138:Tyrian SPE; C115612:single bond; D014867:Water; D017438:Bisphenol A-Glycidyl Methacrylate; C022088:silicon carbide