Shear Bond Strengths of Composite Resin Used to Repair Lithium Disilicate and Feldspathic CAD/CAM Ceramics Treated by Different Lasers (A Comparative in vitro Study)
Author(s): Ola Mohammed Abdul Kadhim* and Mohammed Rashid Aljuboury
Abstract
Aim: This study aimed to evaluate and compare the effect of surface treatments with HF acid, Nd:YAG and Er,Cr:YSGG lasers radiation on Shear Bond Strength (SBS) of nano-hybrid composite resin bonded to two different ceramic materials.
Materials and methods: Sixty specimens of (14*12*3 mm) were prepared from ceramic blocks and divided into two groups (n=30) depending on the type of ceramic materials: Group A: Feldspathic ceramic (cerec block CPC 14/A2C; Sirona dental, Germany) and group B: Lithium disilicate (IPS e.max CAD HT/A2; Ivoclar Vivadent, Shann, Liechtenstein). The obtained specimens were further allocated into six subgroups (n=10) according to the surface treatment methods; A1 and B1: 4.5% HF etching, A2 and B2: 3W Nd:YAG laser, A3 and B3: 3W Er,Cr:YSGG laser. Three additional specimens for each group were prepared for SEM analysis. All specimens were repaired with nano-hybrid composite resin (tetric n-ceram) and thermo cycled for 1000 cycles. SBS was measured using a universal testing machine and the failure mode was evaluated by digital microscope. The obtained data were analyzed using two way ANOVA and Bonferroni’s post-hoc tests (P ≤ 0.05).
Results: The highest SBS values were recorded in HF acid treated groups. Two way ANOVA test revealed a statistical significant difference in SBS values among surface treatment groups (p ≤ 0.05). There was a statistical difference between HF acid and both lasers type (p ≤ 0.05); whilst, no statistical difference in adhesion strength was recorded between Nd:YAG and Er,Cr:YSGG lasers (p>0.05). Statistical analysis revealed that ceramic types did not affect SBS values (p>0.05). SEM analysis revealed that HF acid creates pronounced surface alterations in both types of ceramic materials. Fracture pattern analysis showed cohesive failure only in group A1, while adhesive and mixed failures found in the other treated groups.
Conclusion: prior to repairing, 4.5% HF etching provided the more appropriate surface treatment method regarding the bond strength for both ceramic materials. Neither Nd:YAG nor Er,Cr:YSGG lasers irradiation with the used parameters increase the SBS of composite resin to both ceramics compared to HF etching.