title: Microtensile strength of resin cement bond to indirect composite treated by different output powers of Er:YAG laser.
abstract: The study aimed to evaluate the effect of different output powers of Er:YAG laser on microtensile bonding strength of indirect composite to resin cements.36 indirect composite blocks (GC Gradia DA2, Japan) size 15 × 10 × 10 mm(3) were constructed, and divided into 12 groups, as follows:G1: control group (no treatment); Groups G2 to G6: treated with Er:YAG laser (2,940 nm) in noncontact mode, frequency 20 Hz, pulse duration 470 µs, with output power ranging from 2W to 6W; Groups G7 sandblasting, Groups 8 to G12: as Groups G2 to G 6 with preparatory sandblasting. One specimen from each group was analyzed by SEM; each specimen was fixed to a specialized metal jig using cyanoacrylate (Mitreapel, Beta Kimya San. Ve TIC, Iran) and debonded under tension with a universal testing machine (Zwick, Germany) at a crosshead speed of 0.5 mm min(-1). Sandblasting and laser can improve bond strength above an energy level of 150 mJ. SEM evaluation of laser-treated specimens showed irregularities and deep undercuts. T test analysis showed no significant difference between sandblasted and non-sandblasted group, with laser output power of 0, 100, or 150 mJ (P = 0.666, P = 0.875, and P =  .069); in the specimens irradiated with energy output of 200, 250, or 300 mJ, sandblasted specimens showed higher bond strength than non-sandblasted ones. The results demonstrate that, in composite resin irradiated with laser at energy output of 200-300 mJ, sandblasting might be a suitable procedure to enhance bond strength of resin cement.
authors.affiliation: Restorative Dentistry Department, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Nazanin Zeinab
authors.initials: NZ
authors.lastname: Garshasbzadeh
authors.affiliation: Restorative Dentistry Department, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mansoreh
authors.initials: M
authors.lastname: Mirzaie
authors.affiliation: Restorative Dentistry Department, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Esmaeil
authors.initials: E
authors.lastname: Yassini
authors.affiliation: Laser Research Center of Dentistry, Dental Research Institute, Tehran University of Medial Sciences Tehran, Tehran, Iran.
authors.forename: Sima
authors.initials: S
authors.lastname: Shahabi
authors.affiliation: Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, Genoa, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Benedicenti
authors.affiliation: Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, Genoa, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Angiero
authors.affiliation: PhD Candidate in Laser Dentistry, Laser Research Center of Dentistry, Dental Research Institute, Tehran University of Medial Sciences, Tehran, Iran.
authors.forename: Nasim
authors.initials: N
authors.lastname: Chiniforush
keywords: Er:YAG laser; indirect composite; microtensile strength