Adper single bond 2

With the power of study 80%, significance level P < 0.05, and 20% difference in terms of retention to be detected between the three groups at the end of 18 months, the sample size was 25 teeth in each group (EPI sample size calculation software, CDC, USA). The inclusion criteria consisted of patients aged 20–50 years who had at least three NCCLs with cervico-incisal height of 1–2 mm and average depth of 1 mm. The selected teeth were having healthy periodontium and had antagonist teeth. Patients with extremely poor oral hygiene, severe or chronic periodontitis, or heavy bruxism habits were excluded from the study. The other exclusion criteria were nonvital teeth with clinical and radiographic signs of caries and periapical lesions.
The purpose of the study was explained to the selected patients, and a written informed consent was obtained. In each patient, three teeth were randomly assigned according to the adhesive system used to Group A, total-etch adhesive (Adper^™ Single Bond 2; 3M™ ESPE™), Group B, two-bottle self-etch adhesive (one coat self-etching bond, Coltene/Whaledent Inc., Mahwah, NJ, USA), and Group C, one-bottle self-etch adhesive system (Single-Bond Universal Adhesive; 3M ESPE) by using the lottery method of randomization.

A total of 30 feldspathic porcelain blocks (Ceramco, Dentsply, USA), measuring 3×3×2, were prepared in a porcelain oven (VITA VACUMAT 40 T, VITA Zahnfabrik, Germany) as per the manufacturer’s instructions. Using 600-grit silicon carbide paper (3M ESPE, St. Paul, MN, USA), each of the surfaces of the porcelain samples was polished under water cooling. In order to create surface roughness in all the samples, an intraoral air abrasion device (Microblast, Dental, Microblaster, Denmark) was used to blast 50-μ aluminium oxide particles at a pressure of 50 bars, while placing the device tip 10 mm from the sample’s surface for ten seconds (20 (link), 21 (link)). The porcelain surfaces were exposed to 9.6% hydrofluoric acid for two minutes and then dried with a drying agent (Dry-Rite, pulp dent, USA) to facilitate the drying process. At this stage, the interfacial silane material (Pulpdent, Watertown, USA) was applied on the dried surface for sixty seconds and air-dried. Then, two layers of etch-and-rinse adhesive (Adper Single Bond 2, 3M, ESPE, St. Paul, MN, USA) were applied.

Seven aliquots (1 g each) of demineralized dentin powder were obtained and subjected to the above-mentioned biomodification. Then, specimens in each group were incubated in 1 mL of Adper Single Bond 2 (3M ESPE, St. Paul, MN, USA) for 24 h at 4 °C in the dark, thoroughly rinsed with acetone and repeatedly centrifuged (4 000g for 10 min each) at 4 °C. Enzyme extraction and zymographic analyses were carried out as previously described^{4 (link),21 (link)} to evaluate the effect of PA on the gelatinolytic activity of host-derived MMPs on dentin.
Briefly, the specimens were suspended in the extraction buffer (50 mmol⋅L^−l Tris-HCl, pH 6.0) to ultrasonically extract the enzyme proteins. The supernatants were collected by centrifugation. Then, proteins were precipitated at 4 °C by adding powdered ammonium sulphate, redissolved and further dialysed through a 30-kDa membrane overnight. Total protein concentrations in demineralized dentin powder extracts were determined by Bradford assay (Beyotime Biology, Haimen, China). Dentin proteins were electrophoresed under non-reducing conditions on 7.5% sodium dodecyl sulfate (SDS)–polyacrylamide gels copolymerized with 2 g⋅L⁻¹ gelatin (GMS30071.1; Gemend, Shanghai, China). Gels were stained in 0.2% Coomassie Brilliant Blue R-250 and destained. Wet gelatine zymograms were scanned using an EagleEye II imaging system (Stratagene, Santa Clara, CA, USA).

After the erosive/abrasive challenge, each specimen was carefully cleaned under a
deionized water flow for 2 minutes. Acid etching was performed using 37% phosphoric
acid (Dentsply Ind. Com. Ltda, Petrópolis, RJ, Brazil) for 15 s, which was washed out
for a 30 s. A gentle air-stream was used to promote water evaporation,
which was completed with absorbent paper. Two thin coats of an etch-and-rinse dentin
bonding system (Adper Single Bond 2- 3M ESPE, St. Paul, MN, USA) were subsequently
dispensed with a disposable microbrush and gently air-dried for 2-5 s to allow
solvent evaporation and followed by light curing for 10 s with a 1,000
mW/cm² power density LED unit (Radi cal-SDI, Bayswater, Victoria,
Australia). Thus, the enamel surface was restored with two layers of 2 mm
thickness increments of a nano-filled A2 shade resin composite (Filtek Z350-3M ESPE,
St. Paul, MN, USA) and light-activated for 20 s.

To evaluate the SBS, a cylinder 2 mm high and 4 mm in diameter from the same-name composite was bonded to each composite disk. For bonding the new composite, the surface of the composite disk was first roughened with diamond bur (Tizkavan-Iran) and surface etching with 35% phosphoric acid (Voco, Cuxhaven, Germany) for 20 s and washing for 15 s and then drying for 10 s. Then, silane was applied on the surface of aged composite (Monobond-S, Ivoclar Vivadent) and we waited for 4 min for the solvent to evaporate. Then, using a microbrush, two layers of fifth-generation dentin bonding agent (3M ESPE, Adper Single Bond 2, USA) was applied on the surface and dried for 5 s by air spray and light cured for 20 s at a distance of 1 mm. Finally, one layer of new, same-name composite 2 mm thick was placed on the surface and cured for 40 s.
SBS testing was performed using a universal testing machine, set at 500 kg of force and a crosshead speed of 1 mm/min. The breakage force (Newton) was divided by the surface area (12.566 mm²) to calculate SBS in mega Pascal (MPa).
Detached specimens were examined under stereomicroscopy at ×20 and divided into three types of adhesive, cohesive, or hybrid fractures.