الفهرس 
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Abstract
Aim: This study was carried out to investigate the effect of Er:Yag laser ablation on the bonding
efficacy and durability of ceramic blocks to enamel and dentin using contemporary resin
cements.
Materials and methods: Half of exposed flattened labial and occlusal surface of 60 upper
central teeth and 60 molar teeth respectively were marked with a permanent felt-tip marker.
Subsequently, these marks were erased using high speed cylindrical carbide bur # (C21.314.008)
(EDENTA AG, Switzerland) in bur-prepared groups (B). The other half was marked and the
marks were erased using an Er:YAG laser (Fidelis, Fotona ) in laser-ablated groups (L). The
prepared teeth were divided into three groups of 20 teeth each according to the type of resin
cement used to lute 3mm thick ceramic sections; either conventional resin cement with
pretreatment with either etch-and-rinse (E&R) or self-etch (SE) adhesive or the direct use of selfadhesive
cement (SA). After cementation, the teeth were stored in artificial saliva then half of the
specimens from each subgroup (10 teeth) were tested after 24 hours (I). The other half was aged
by storage for six month (A). 7 teeth from each subgroup were randomly selected for the microtensile
bond strength (μTBS) test. Meanwhile, the remaining 3 teeth were allocated for the ultramorphological
analysis.
Results: In the enamel group, laser ablation didn’t influence the bonding performance
of (E&R) and (SE) at both 24 hours and 6 months storage in artificial saliva. Moreover, when
(SA) was used, there was no statistically significant difference between (μTBS) of B and L
initially. Meanwhile, laser ablation improved the bonding ability of (SA) after aging.
Furthermore, with the three tested resin cements, the results indicate no degradation of (μTBS)
after aging with B and L. Moreover, (E&R) exhibited the highest bond strength to B and L. For
the dentin group, there was no statistical significant difference between (μTBS) of B and L
groups with both (E&R) and (SE) systems after 24 hours storage. Meanwhile, after aging,
(μTBS) of B (E&R) and B (SE) groups significantly decreased. On the contrary, L groups
restored with (E&R) and (SE) were not affected by aging and their (μTBS) remained stable after
6 aging. (SA) cement showed significant higher (μTBS) to L when tested after 24 hours. On the
other hand, its bond strength to B significantly increased after aging, to become statistically
similar to L, while the bond strength of the same cement to L remained stable after aging.
Clinical Significance: Utilizing Er:Yag laser for tooth preparation is a viable alternative that
enhances durable bonding of indirect machinable ceramic restorations.