MATERIALS AND METHODS: Seventy-two epoxy replicated dies from two prepared maxillary right central incisors acrylic typodont were divided into two groups of different preparation designs (n = 36): Group I, incisal butt-joint, and Group P, incisal overlap. Each group was further subdivided into two equal groups according to ceramic material (n = 18): Group E, IPS e.max CAD, and Group T, Tessera advanced lithium disilicate (ALD) CAD-CAM blocks. The replica technique was used to assess the internal fit using a stereomicroscope at 45× magnification. Laminate veneers were cemented to their corresponding epoxy dies, then the vertical marginal gap was evaluated before and after thermal cycling. Repeated measures analysis of variance (ANOVA) were used for marginal fit data and 2-way ANOVA for internal fit measurements (α = 0.05).
RESULTS: For internal fit, there were no significant differences between tested groups. For vertical marginal gap results, two-way ANOVA showed that only aging had a significant effect on the vertical marginal gap (p
METHODS: One hundred and twenty posterior teeth had their occlusal enamel removed, then the specimens were divided into two main groups according to dentin substrates; SoD and CID, three subgroups according to pretreatments protocols control (no pretreatment), NaOCl-treated, and Er, Cr:YSGG-treated and two divisions according to antioxidant application (with and without sodium ascorbate (SA) application). All-Bond Universal (ABU) universal adhesives was applied in self-etch (SE) mode then resin composite discs were built. The specimens were stored in distilled water for 24-hr at 37°C before SBS testing. Three-way ANOVA and Tukey HSD tests were used for data analysis (a = 0.05).
RESULTS: 6% NaOCl resulted in a significant reduction in SBS in SoD without antioxidant application. 10% SA application showed significant increase in SBS for 6% NaOCl group only in SoD. Laser application recorded a significantly higher SBS compared to 6% NaOCl group without or with antioxidant application, while 10% SA application revealed a significant increase in SBS for control group only.
CONCLUSIONS: Er, Cr:YSGG laser irradiation followed by antioxidant application has the potential to enhance the bonding quality of both tested dentin substrates. NaOCl application has significantly compromised the bonding to SoD and CID substrates.
METHODS: Extracted human mandibular third molars were sectioned into 54 buccal and lingual halves. Acid-resistant nail varnish was applied to each half, except for two enamel windows. Enamel surface microhardness, energy-dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM) analyses were conducted to evaluate enamel surfaces at baseline, following demineralization with 37% phosphoric acid, and after each hydrogel application and remineralization for two, four, and six days. Remineralization was performed using a phosphate solution at 37°C.
RESULTS: At day 6 following remineralization, a statistically significant higher mean microhardness was recorded in n-HA-EMD-agarose hydrogel (260.87 ± 3.52) as compared to EMD-agarose hydrogel (244.63 ± 2.76) (p = 0.027). Similarly, n-HA-EMD-agarose hydrogel showed a higher mean calcium (46.31 ± 2.78), phosphorous (24.92 ± 0.826), and fluoride (0.909 ± 0.053) weight percentage compared to EMD-agarose hydrogel calcium (19.64 ± 1.092), phosphorous (19.64 ± 1.092), and fluoride (0.7033 ± 0.0624) weight percentage (p < 0.05). Further, SEM analysis revealed a substantial deposition of n-HA following the application of the n-HA-EMD-agarose hydrogel, whereas the EMD-agarose exhibited a relatively smooth enamel surface with less visible enamel rods due to mineral deposition.
CONCLUSION: The combined n-HA-EMD-agarose hydrogel demonstrated improved surface microhardness of the remineralized enamel and enhanced mineral content deposition, indicating its potential as a biomimetic approach for dental enamel repair.