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Objective: The present clinical trial was conducted to evaluate the clinical performance of the biomimetic, bilayered structure utilizing a fiber reinforced bulk fill resin composite with a nanohybrid capping layer, compared to incremental packing of nanohybrid resin composite, in deep proximal cavities in permanent molars. Material and methods: A total of 36 deep proximal cavities in vital molars were restored either with a bilayered structure of fiber reinforced composite resin as a dentine substitute and a capping layer of nanohybrid composite resin (n=18) or conventional, nanohybrid composite resin incrementation (n=18). The restorations were assessed over a period of 12 months using the modified USPHS criteria. The criteria evaluated were: fracture and retention, marginal integrity, marginal discoloration, anatomic form, proximal contact, surface texture, radiographic evaluation, postoperative sensitivity and secondary caries. Results: There was no statistically or clinically significant difference between fiber-reinforced resin composite and conventional incremental resin composite. There was no risk for failure regarding all the evaluated modified USPHS criteria for both materials after 12 months (RR= 1(95% CI 0.0209 to 47.8503; P =1.0000)). Conclusion: The biomimetic approach utilizing a fiber reinforced resin composite dentine substitute showed a comparable clinical performance to nanohybrid resin composite incrementation. Bulk fill fiber reinforced resin composite is an efficient alternative in restoration of deep proximal cavities in posterior teeth. Further long-term studies are necessary to confirm these results.
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Introduction: Erbium laser ablation as a method of tooth preparation and conditioning has shown promising results. Although previous studies have adopted various combinations of different laser parameters and several dentin adhesive systems, very few have investigated combining high-level and low-level ER:YAG lasers with Universal adhesives. This study aimed to assess the impact of using low-energy irradiation on the surface micro-topography and shear bond strength (SBS) of universal adhesive (UA) to the erbium:yttrium-aluminum-garnet (Er:YAG) laser-ablated dentin substrate, bonded in etch-and-rinse or self-etch adhesive mode. Methods: Eighty-seven extracted molars were sectioned to expose flat occlusal dentin surface; 60 teeth were divided equally into three groups according to the surface treatment; bur-cutting (B), Er:YAG high-energy laser cutting (L1 - 200 mJ, 20 Hz, 50 µs pulse), or L1 followed by low-energy laser modification (L1 /L2 - 80 mJ, 10 Hz, 50 µs pulse). Then each group was equally divided into two groups (n=10) according to the mode of application of the universal adhesive; either etch-and-rinse (ER) or self-etching (SE). The samples were subjected to thermocycling (5000 cycle between 5°C and 55°C), and SBS was tested. Two-way ANOVA and Tukey post hoc test were used to analyze the results. The remaining 27 samples were used to investigate the effect of the treatment on the topography of the treated dentin surfaces using a scanning electron microscope (SEM). Results: B/SE recorded the highest SBS (25.48 ± 2.6 MPa) followed by B/ER (23.20 ± 6.8 MPa) and L1 /L2 /SE (22.94 ± 4.1 MPa) and with no statistically significant difference between these groups (P >0.05). The lowest SBS results (P <0.05) were recorded for L1/SE (12.22 ± 3 MPa). No statistical differences were found between the SBS of L1 /L2 /ER and L1 /ER groups or between the SBS of L1 /L2 / ER and L1 /L2 /SE groups. Conclusion: A subsequent treatment of the Er:YAG laser-ablated dentin with low-energy laser modification mode (LMM) enhances the SBS of the tested UA when applied in SE mode.
RESUMEN
OBJECTIVES: This in vitro study determined the effect of enamel pretreatment with phosphoric acid and ethylenediaminetetraacetic acid (EDTA) on the bond strength of strong, intermediary strong, and mild self-etching adhesive systems. METHODS: Ninety sound human premolars were used. Resin composite cylinders were bonded to flat ground enamel surfaces using three self-etching adhesive systems: strong Adper Prompt L-Pop (pH=0.9-1.0), intermediary strong AdheSE (pH=1.6-1.7), and mild Frog (pH=2). Adhesive systems were applied either according to manufacturer instructions (control) or after pretreatment with either phosphoric acid or EDTA (n=10). After 24 hours, shear bond strength was tested using a universal testing machine at a cross-head speed of 0.5 mm/minute. Ultra-morphological characterization of the surface topography and resin/enamel interfaces as well as representative fractured enamel specimens were examined using scanning electron microscopy (SEM). RESULTS: Neither surface pretreatment statistically increased the mean shear bond strength values of either the strong or the intermediary strong self-etching adhesive systems. However, phosphoric acid pretreatment significantly increased the mean shear bond strength values of the mild self-etching adhesive system. SEM examination of enamel surface topography showed that phosphoric acid pretreatment deepened the same etching pattern of the strong and intermediary strong adhesive systems but converted the irregular etching pattern of the mild self-etching adhesive system to a regular etching pattern. SEM examination of the resin/enamel interface revealed that deepening of the etching pattern was consistent with increase in the length of resin tags. EDTA pretreatment had a negligible effect on ultra-morphological features. CONCLUSIONS: Use of phosphoric acid pretreatment can be beneficial with mild self-etching adhesive systems for bonding to enamel.
RESUMEN
PURPOSE: To evaluate the effect of 6 irrigant regimens on the microshear bond strength of different adhesives to pulp chamber dentin and to determine their interfacial morphology by SEM. MATERIALS AND METHODS: Forty-three human molars were split into halves and ground to provide flat pulp chamber dentin. Eighty-five halves were used. The specimens were assigned to 6 groups according to the irrigant regimen used. Group I (n=10) was irrigated with distilled water (control). The remaining 5 groups (n=15 each) were irrigated with 5.25% NaOCl followed by either 5.25% NaOCl, 17% EDTA, benzalkonium chloride (Tubilcid Plus) or MTAD (Biopure), either rinsed or not. Irrigated specimens were bonded using Clearfil S3 Bond or Adper Single Bond 2, which was employed with or without etching. Resin composite cylinders were bonded using tygon tubes for microshear bond strength testing. Data were analyzed using two-way ANOVA followed by Tukey's post-hoc test. Representative specimens of each group were prepared from 17 further molars for interfacial SEM examination. RESULTS: The different irrigant regimens used did not significantly alter the microshear bond strength values using either of the bonding systems, except NaOCl, which significantly reduced the microshear bond strength values with Adper Single Bond 2. Bonding irrigated specimens directly using the Adper Single Bond 2 without prior etching provided significantly reduced values. CONCLUSION: The irrigant regimens examined could be used safely prior to bonding except for the NaOCl, which should be negated if it is to be followed by Adper Single Bond 2, and the etching step cannot be omitted if an etch-and-rinse adhesive system is the adhesive of choice.