Effects of prolonged light exposure times on water sorption, solubility and cross-linking density of simplified etch-and-rinse adhesives.
OBJECTIVE
This study evaluated the effects of light exposure times on water sorption, solubility, and polymer cross-linking density of simplified etch-and-rinse adhesives.


METHODS
Four commercial adhesives (XP Bond, Adper Single Bond 2, Tetric N-Bond, and Ambar) were selected, and resin disks 5 mm in diameter and 1.0 mm thick were prepared and light cured for 20, 40, or 80 s using an LED light-curing unit at 1200 mW/cm2. Water sorption and solubility were evaluated over a 28-day period. For polymer cross-linking density, additional specimens were prepared and their Knoop hardness measured before and after immersion in 100% ethanol. The data from each test were evaluated using a two-way ANOVA and Tukey's test (α = 0.05).


RESULTS
The XP Bond adhesive showed higher water sorption (similar to Adper Single Bond 2) and solubility (p < 0.05) than did the other materials. Prolonged exposure times did not reduce the water sorption but did reduce the solubility of all tested materials (p < 0.05). For Ambar, the increase in the exposure time resulted in a significantly lower percent reduction in hardness.


CONCLUSIONS
Water sorption, solubility, and cross-linking density of the materials selected in this study seem to be mainly influenced by the adhesive composition. Prolonged light exposure times reduced the solubility of the materials.
Letícia
L
Wambier
Tamirez
T
Malaquias
Denise Stadler
DS
Wambier
Rafael T
RT
Patzlaff
José
J
Bauer
Alessandro D
AD
Loguercio
Alessandra
A
Reis
D000134:Acid Etching, Dental / Q000379:methods; D000327:Adsorption; D003188:Composite Resins / Q000737:chemistry / Q000528:radiation effects; D055117:Curing Lights, Dental; D003738:Dental Cements / Q000737:chemistry / Q000528:radiation effects; D017220:Dentin-Bonding Agents / Q000737:chemistry / Q000528:radiation effects; D000431:Ethanol / Q000737:chemistry; D006244:Hardness; D006801:Humans; D007101:Immersion; D008027:Light; D055115:Light-Curing of Dental Adhesives / Q000295:instrumentation; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry / Q000528:radiation effects; D058105:Polymerization; D019279:Resin Cements / Q000737:chemistry*; D012995:Solubility; D012997:Solvents / Q000737:chemistry; D013997:Time Factors; D014867:Water / Q000737:chemistry*
C554641:Adper single bond 2; D003188:Composite Resins; D003738:Dental Cements; D017220:Dentin-Bonding Agents; D008689:Methacrylates; D019279:Resin Cements; D012997:Solvents; C090969:Tetric; C532387:XP-Bond; D014867:Water; D000431:Ethanol