Environmental observation of enamel crack and resin-tooth cavity gap formation

Takako Yoshikawa, DDS, PhD,a Makoto Morigami, DDS, PhD,b Alireza Sadr, DDS, PhD,c and Junji Tagami, DDS, PhDa

aCariology and Operative Dentistry, Department of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), bDepartment of Dentistry, Toranomon Hospital, Tokyo, Japan, and cDepartment of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, WA, USA

Purpose: The aim of this study was to observe marginal sealing and resin composite adaptation to cavity walls using the dye penetration test and environmental scanning electron microscope.
Materials and Methods: Cylindrical cavities were prepared on cervical regions of teeth. Teeth were restored with Clearfil Liner Bond 2V adhesive and filled with Clearfil Photo Bright or Palfique Estelite resin composites. These resin composites were cured with a conventional light-curing method. After thermal cycling, the specimens were subjected to the dye penetration test to evaluate marginal sealing and resin composites adaptation to the cavity walls. These resin-tooth interfaces were then observed using environmental scanning electron microscope.
Results: namel crack formation was observed in all specimens. Gap formation between the resin composite and cavity walls was observed for both resin composites.
Conclusion: Environmental scanning electron microscope showed high enamel crack formation for both resin composites after light curing. Enamel cracks were located at 25-100 μm from the resin-enamel interface on environmental scanning electron microscope observations. Enamel cracks were observed in the enamel surface to the dentin-enamel junction. Environmental scanning electron microscope showed cavity wall gap formation in the dentin-adhesive interface or resin-adhesive interface.
(Asian Pac J Dent 2015; 15: 13-19.)
Key Words: adaptation, dye penetration test, environmental SEM, polymerization, resin composite