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Dental pulp cells (DPCs) represent good candidates for the regeneration of dental tissue. This study aimed to evaluate the growth and differentiation potential of DPCs cultured inside demineralized dentin tubules in vivo. Six green fluorescent protein-transgenic rats (body weight 100 g each) and thirty-two Sprague-Dawley (SD) male rats (body weight 250 g each) were used for DPC collection and dentin tubules preparation and transplantation, respectively. Third-passage DPCs with or without collagen gels were loaded into demineralized dentin tubules. Both types of grafts were transplanted into the rectus abdominis muscles of SD rats and were harvested after 21 days. The expression of alkaline phosphatase (ALP), bone sialoprotein (BSP), osteopontin (OPN), nestin, and dentin sialoprotein (DSP) was analyzed by immunohistochemistry. Histological analysis showed that DPCs in the collagen gel formed an osteodentin-like hard tissue matrix after 21 days. Increased positive immunoreactivity for ALP, BSP, OPN, nestin, and DSP was observed in experimental groups compared with control. Our results demonstrate that DPCs in collagen gel inside demineralized dentin tubules show increased growth and differentiation.

Objective: The aim was to compare restorative marginal integrity of ceramic crowns luted with bioactive and resin cements using micro-computed tomography (micro-CT) microleakage evaluations and bond strength assessment., Methods: Thirty molar teeth were prepared by sectioning and polishing for dentin exposure for resin cement build-ups. Teeth were randomly divided among three groups of cements: (1) bioactive (ACTIVA); (2) glass ionomer cement (GIC; Ketac Cem); and (3) resin luting agent (Nexus 3). Bonding regime and build-ups (4 mm × 2 mm) were performed using the recommended protocol. For microleakage assessment, 30 premolar teeth were prepared for dentin-bonded crowns using lithium disilicate ceramic and the computer-aided design and computer-aided manufacturing technique. Crowns were cemented with standard load, cement amount, and duration using three cements (Group A: bioactive; Group B: GIC; Group C: resin) and photopolymerized. Cemented crowns were evaluated for volumetric infiltration using micro-CT (Skyscan, Bruker 1173- at 86 kV, 93 µA, 620 ms) after immersion in 50% solution of silver nitrate (AgNO 3 ) (24 hours). Shear bond strength (SBS) was assessed by fracture of cement build-ups at a cross-head speed of 0.5 mm/min in a universal testing machine., Results: Mean SBS among bioactive (21.54 ± 3.834 MPa) specimens was significantly higher than that for GIC (14.08 ± 3.25 MPa) specimens ( p < 0.01), but they were comparable to resin samples ( p > 0.05) (24.73 ± 4.32 MPa). Microleakage was significantly lower in crowns luted with bioactive (0.381 ± 0.134) cement compared to GIC (1.057 ± 0.399 mm 3 ) ( p < 0.01) and resin (0.734 ± 0.166 mm 3 ) ( p = 0.014) cemented crowns. The type of luting agent had a significant influence on the microleakage of crowns and bond strength to dentin ( p < 0.05)., Conclusion: Bioactive cement exhibited less microleakage and comparable SBS to resin luting agents in in vitro conditions.

Objective. Our study is aimed at preparing an experimental adhesive (EA) and assessing the influence of adding 5-10 wt.% concentrations of zinc oxide (ZnO) nanoparticles on the adhesive's mechanical properties. Methods. Field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) spectroscopy were employed to investigate the morphology and elemental distribution of the filler nanoparticles. To examine the adhesive properties, microtensile bond strength (μTBS) testing, an investigation of the rheological properties, degree of conversion (DC), and analysis of the interface between the adhesive and dentin were carried out. Results. The SEM micrographs of ZnO nanoparticles demonstrated spherical agglomerates. The EDX plotting confirmed the incidence of Zn and oxygen (O) in the ZnO nanoparticles. The highest μTBS was observed for nonthermocycled (NTC) 5 wt.% ZnO group (32.11 ± 3.60 MPa), followed by the NTC-10 wt.% ZnO group (30.04 ± 3.24 MPa). Most of the failures observed were adhesive in nature. A gradual reduction in the viscosity was observed at higher angular frequencies, and the addition of 5 and 10 wt.% ZnO to the composition of the EA lowered its viscosity. The 5 wt.% ZnO group demonstrated suitable dentin interaction by showing the formation of resin tags, while for the 10 wt.% ZnO group, compromised resin tag formation was detected. DC was significantly higher in the 0% ZnO (EA) group. Conclusion. The reinforcement of the EA with 5 and 10 wt.% concentrations of ZnO nanoparticles produced an improvement in the adhesive's μTBS. However, a reduced viscosity was observed for both nanoparticle-reinforced adhesives, and a negotiated dentin interaction was seen for 10 wt.% ZnO adhesive group. Further research exploring the influence of more filler concentrations on diverse adhesive properties is recommended. [ABSTRACT FROM AUTHOR]

• The highest shear bond strength value was observed in group 1 (non-infected dentin). • The lowest bond strength value was displayed in group 3 (Photodynamic therapy on infected dentin). • Carious dentin showed lower bond strength to composite resin as compared to non-carious dentin. To evaluate the adhesive bond integrity (shear bond strength-SBS) of composite resin bonded to carious dentin using chlorhexidine gluconate (CHX), Er,Cr:YSGG laser (ECYL) and photodynamic therapy (PDT). Thirty carious and ten non-carious mandibular teeth were collected through non-traumatic extraction. All samples were embedded in polyvinyl cross-sections to the cemento-enamel junction. The preparation of caries-affected dentin was performed by grinding the specimens using silicon carbide discs. All specimens were randomly allocated in to four groups (n = 10). Group 1, non-affected dentin with no disinfection; Group 2, caries affected dentin treated with 2% CHX; Group 3, affected dentin disinfected with PDT [100 mg/L methylene blue solution (MBS) and Diode laser]; Group 4, affected dentin treated with ECYL. Self-etch adhesive was smeared on all specimens for 10 s and photopolymerized for 10 s. All specimens were placed in an incubator with humid environment for 24 h at 37 °C followed by positioning in universal testing machine for SBS testing. Failure mode examination of debonded samples was performed by a stereomicroscope. Analysis of variance (ANOVA) was used for inter group comparison through mean and standard deviation of each group. For multiple group comparison Tukey HSD was employed. Level of significance was established at p < 0.05. The highest SBS value was observed in group 1 (24.98 ± 1.59 MPa). Whereas, the lowest bond strength was displayed by group 3 (14.22 ± 1.40 MPa) specimens. Lased dentin in group 4 (15.89 ± 3.22 MPa) exhibited SBS values comparable to group 3 (14.22 ± 1.40 MPa). Group 2 (CHX-18.25 ± 1.29 MPa) exhibited statistically significant difference compared to all experimental groups (p < 0.05). Adhesive bond strength of disinfected carious dentin was higher with CHX treatment as compared to Photodynamic therapy and Er,Cr: YSGG laser treatment. Carious dentin showed lower bond strength to composite resin as compared to non-carious dentin. [ABSTRACT FROM AUTHOR]