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Enhancement of bonding to enamel and dentin prepared by Er,Cr:YSGG laser
Author(s) -
Obeidi Ali,
McCracken Michael S.,
Liu PerngRu,
Litaker Mark S.,
Beck Preston,
Rahemtulla Firoz
Publication year - 2009
Publication title -
lasers in surgery and medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 112
eISSN - 1096-9101
pISSN - 0196-8092
DOI - 10.1002/lsm.20790
Subject(s) - dentin , enamel paint , bond strength , materials science , dentistry , irradiation , adhesive , composite material , dental bonding , layer (electronics) , medicine , physics , nuclear physics
Background and Objective Erbium lasers are potential tools to remove caries and dental hard tissue but bond strengths of composites to those preparations are reported to be lower than conventional methods. The purpose of this study was to evaluate the effect of mechanical excavation and/or chemical alteration on bond strength of composites to laser irradiated enamel and dentin. Materials and Methods Seventy‐two premolars were ground to obtain flat enamel (E, n = 36) or dentin (D, n = 36) surfaces in both buccal and lingual cusps, divided into: LaserExcavation (LEx), LaserNo‐excavation (LNex), and Bur (B) groups. The laser groups were irradiated for 10 seconds by Er,Cr:YSGG laser [4.5 W, 60% air, 80% water (enamel) 3 W, 60% air, 70% water (dentin)]. Irradiated surfaces in the excavation groups (Ex) were then mechanically smoothed with a dental excavator, prepared surfaces were then etched (37% H 3 PO 4 ) for 20 or 40 seconds (enamel) and 15 or 30 seconds (dentin), washed (20 seconds), adhesive was applied(Single Bond Plus), and light cured (20 seconds). A composite cylinder (Filtek Supreme Plus) formed, placed and light cured (40 seconds). The specimens were stored (37°C,48 hours), shear bond tested (1 mm/minute), and statistically analyzed ( P < 0.05). Results Mixed‐model ANOVA showed significant differences between enamel ( P = 0.0091) and between dentin groups ( P = 0.0035). Tukey/Kramer showed mean shear bond strength (SBS±SE) of EB40 (27.01±2.38 MPa) was significantly higher than ELNoExc20 (14.39±2.5 MPa) and ELExc40 (14.90±2.28 MPa). Also DB30 (17.57± 1.67 MPa) and DLExc30 (18.6±1.74 MPa) were significantly higher than DLNoExc15 (9.56±1.86 MPa). Conclusion Increasing the etching time up to 40 seconds or excavation of the laser prepared surface (but not the combination) may increase the bond strength to the level of conventional methods in enamel but excavation has a greater influence in dentin. Also the combination of both methods [excavation+longer etching time (30 seconds)] exhibit significantly better results in dentin. Mode of failure study showed mechanical excavation in both enamel and dentin can significantly reduce the cohesive failure in tooth structure. Lasers Surg. Med. 41:454–462, 2009. © 2009 Wiley‐Liss, Inc.