Microleakage and gap formation of resin composite restorations polymerized with different techniques.
OBJECTIVE
To evaluate the effect of different polymerization techniques on microleakage and gap formation of resin-based composite restorations. One correlation test was also carried out between these methodologies.


METHODS
180 vertical slot cavities were prepared in bovine teeth and filled with Z250/Single Bond system, for the following six groups (n=30): Soft-start I - 10 seconds at 75 mW/cm2 + 30 seconds at 560 mW/cm2; Soft-start II - 10 seconds at 190 mW/cm2 + 30 seconds at 560 mW/cm2; Pulse delay - 3 seconds at 300 mW/cm2 + 5 minutes waiting + 30 seconds at 560 mW/cm2; Plasma arc - 3 seconds at 1,500 mW/cm2; High intensity - 40 seconds at 810 mW/cm2; Conventional (control) - 40 seconds at 560 mW/cm2. After polishing, epoxy replicas were prepared for electron microscopy analysis (n=10), at x500 magnification. The samples were thermocycled, new epoxy replicas were prepared, and the teeth were immersed in 2% methylene blue dye solution for 4 hours. Marginal gaps were evaluated again and the microleakage was assessed.


RESULTS
No statistical difference among polymerization techniques was observed for microleakage (Kruskal-Wallis test). For gap formation there was no statistical difference among polymerization techniques either before or after thermocycling (Tukey test). Conversely, thermocycling significantly increased the gap formation for all groups. No correlation (Spearman correlation test) was observed for the results of microleakage and gap formation.
Department of Restorative Dentistry, Guarulhos University, Brazil.
Cristiane Mariote
CM
Amaral
Alessandra Rezende
AR
Peris
Glaucia Maria Bovi
GM
Ambrosano
Luiz André Freire
LA
Pimenta
D000818:Animals; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry / Q000528:radiation effects; D002417:Cattle; D004396:Coloring Agents; D003188:Composite Resins / Q000737:chemistry* / Q000528:radiation effects; D003737:Dental Cavity Preparation / Q000145:classification; D003763:Dental Leakage / Q000145:classification*; D018772:Dental Marginal Adaptation; D003775:Dental Polishing; D003793:Dental Restoration, Permanent; D008029:Lighting / Q000295:instrumentation; D008422:Materials Testing; D008751:Methylene Blue; D008854:Microscopy, Electron; D011108:Polymers / Q000737:chemistry / Q000528:radiation effects; D018709:Statistics, Nonparametric; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors
D004396:Coloring Agents; D003188:Composite Resins; C444701:Filtek Z250; D011108:Polymers; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate; D008751:Methylene Blue