Effect of resin-coating technique on coronal leakage inhibition in endodontically treated teeth

Rena Maruoka, DDS, PhD(a) Toru Nikaido, DDS, PhD,(a) Masaomi Ikeda, RDT, BSc,(a) Richard M. Foxton, BDS, PhD, MFDS, RCS(Ed),(b) and Junji Tagami, DDS, PhD(a,c)

(a) Cariology and Operative Dentistry, Department of Restorative Sciences, Graduate School, Tokyo Medical and Dental University, Tokyo, 113-8549, Japan
(b) Department of Conservative Dentistry, King’s College London Dental Institute at Guy’s, King’s College and St. Thomas`s Hospitals, London, UK
(c) Center of Excellence Program for Frontier Research of Molecular Destruction and Reconstruction of Tooth and Bone, Tokyo Medical and Dental University, Tokyo, Japan

Purpose: To evaluate the effect of the resin coating technique on coronal leakage inhibition in endodontically treated teeth.
Materials and Methods: Thirty-six extracted human incisors were cut at the level of the cemento-enamel junction and standard endodontic obturations were made. They were divided into two groups; resin-coating group, and non-coating group. For the resin-coating group, the dentin surfaces were coated with either a one-step coating material, Hybrid Bond or a combination of Hybrid Bond and a low viscosity microfilled resin, SB Coat. They were subjected to thermal cycling for 0 or 1,000 times. Following this, the specimens were coated with nail varnish leaving the coronal openings exposed. The apical parts were sealed with utility wax. They were then immersed in 1% methylene blue solution for 48 hours. After removal from the dye, the teeth were sectioned faciolingually using a diamond saw. Linear dye penetration (in mm) from the cementoenamel junction was measured with photomicroscope. The number of the specimens was 12 for each group. The data were analyzed by two-way ANOVA and Dunnett’s T3 test (p=0.05).
Results: Coronal leakage was influenced by the coating material and thermal stress (p<0.05). The resin-coating groups of HB and HB/SB had significantly less dye penetration compared with the non-coating group (p<0.05). The combination of Hybrid Bond and SB coat effectively inhibited coronal leakage (p<0.05).
Conclusion: The resin coating technique effectively minimized coronal leakage of endodontically treated teeth. Thermal stress demonstrated acceleration of dye penetration into the obturated root canal space. (Int Chin J Dent 2007; 7: 1-6.)

Key Words: coronal leakage, endodontically treated tooth, resin coating technique, thermal cycling.