Riboflavin and Its Effect on Dentin Bond Strength: Considerations for Clinical Applicability—An In Vitro Study

Bioactive collagen crosslinkers propose to render the dentin hybrid layer less perceptive to hydrolytic challenge. This study aims to evaluate whether bond strength of dental resin composite to dentin benefits from riboflavin (RB)-sensitized crosslinking when used in a clinically applicable protocol. A total of 300 human dentin specimens were prepared consistent with the requirements for a macro-shear bond test. RB was applied on dentin, either incorporated in the primer (RBp) of a two-step self-etch adhesive or as an aqueous solution (RBs) before applying the adhesive, and blue light from a commercial polymerization device was used for RB photoactivation. Bonding protocol executed according to the manufacturer’s information served as control. Groups (n = 20) were tested after 1 week, 1 month, 3 months, 6 months or 1 year immersion times (37 °C, distilled water). The different application methods of RB significantly influenced bond strength (p < 0.001) with a medium impact (η2p = 0.119). After 1 year immersion, post hoc analysis identified a significant advantage for RB groups compared to RBp (p = 0.018), which is attributed to a pH-/solvent-dependent efficiency of RB-sensitized crosslinking, stressing the importance of formulation adjustments. We developed an application protocol for RB-sensitized crosslinking with emphasis on clinical applicability to test its performance against a gold-standard adhesive, and are confident that, with a few adjustments to the application solution, RB-sensitized crosslinking can improve the longevity of adhesive restorations in clinics.

Impact of Various Cross Linking Agents on Dentin Adhesive Systems - an In-vitro Study

Aims and Objectives: The main aim of this study is to compare and evaluate the shear bond strength of composite resin using a total etch adhesive and self-etch adhesive after treatment with different collagen cross-linking agents. Materials and Methods: Forty freshly extracted human maxillary central incisors were taken. The proximal dentin was exposed, cavities were prepared on mesial and distal of each tooth. The specimens were randomly divided into two groups based on bonding agent applied-Group A and Group B i.e universal bonding agent and all in one bonding agent respectively and are subdivided into four groups based on the surface treatment of dentin. Group I A (n=10) Control-total etch(CTE); Group II A (n=10) Sodium Ascorbate-total etch (STE); Group III A (n=10)- Proanthocyanidin total etch(PTE); Group IV A (n=10)- Chitosan total etch (CHTE); Group I B (n=10) Control-self etch (CSE); Group II B (n=10) Sodium Ascorbate-self etch(SSE); Group III B (n=10)- Proanthocyanidin self-etch (PSE); and Group IV B (n=10) - Chitosan self-etch (CHSE). Shear bond strength of the specimens are tested with universal testing machine, and the data was statistically analysed with one way ANOVA. Results: Significantly higher shear bond strength to dentin was observed in teeth treated with 6.5% Proanthocyanidin Total etch, 10% Sodium Ascorbate Total etch and 1% Chitosan acetate compared to the control group. No significant difference was seen with self-etch treated groups. Conclusion: Dentin surface pretreatment with 6.5% Proanthocyanidin, 10% Sodium Ascorbate and 1% Chitosan acetate results in significant enhancement in bond strength of composite resin to deep dentin.

Effect of eggshell powder application on the shear bond strength of bulk-fill resin composite to bleached enamel

Objective To investigate experimental eggshell powder (ESP) solution application effect on shear bond strength (SBS) test timing of bulk-fill resin composite to bleached enamel. Methods Eighty bovine-extracted anterior teeth were alienated to eight groups (n = 10), representing shear bond strength test timing periods (immediate or delayed) and the remineralizing agents investigated (MI paste Plus and ESP solution). Enamel surfaces were bleached using in-office chemical bleaching agent and the two remineralizing agents were applied then self-etch adhesive and bulk-fill resin composite were performed at 24 h and 14 d before SBS test was done. One-way ANOVA followed by Tukey post hoc test was performed for statistical analysis. Results The control groups showed the highest mean values, while the bleached enamel groups recorded the least mean values. ESP bleached enamel group recorded a significantly higher mean SBS values than MI paste Plus bleached group. Delayed SBS groups showed higher mean values than immediate SBS groups except for control group. Conclusions ESP had a positive and significant effect on SBS of bulk-fill resin composite to bleached enamel surface. Delaying the bonding procedure and restoration of the bleached teeth using resin composite restorations results in a better bond durability.

Evaluation of Dentin Microroughness and Composite Bond Strength After Multiple Uses of Diamond Burs

Using a bur multiple times to prepare dental structure may produce a smoother final surface on dentin than a new one. This superficial roughness may affect adhesion with resin-based materials by modifying the substrates’ characteristics. The aim of this study was to evaluate the effect of multiple uses of diamond burs on dentin’s superficial microroughness and bond strength with resin composite when using a self-etch adhesive. Diamond dental burs were used to simulate a preparation (dentin flat surface) on extracted third molars. Samples were distributed into groups according to burs’ number of previous uses as follows: 0, 1, 5 and 10. Scanning electron microscopy images at 70x, 350x, and 1000x were used to illustrate burs’ deformation. Each specimen’s dentin microroughness was measured three times to compare between experimental groups and the micro-shear bond strength test (n=15) was performed for the 0 and 10 uses groups using a universal adhesive in a self-etching mode. Diamond crystals wear and dislodgements were evident among groups where the burs were used more times. As the number of uses increased the mean microroughness of the dentin surface decreased with significant differences between the 0 and 10 uses groups. No statistical differences between experimental groups resulted from bond strength tests. When using a universal adhesive in a self-etching mode, the number of previous uses of a diamond bur seems to have no significant effect on dentin/resin composite bond strength.

Effects of Desensitizers, Temporary Cements, and Dentin Cleaning Methods on the Bond Strength of Self-Etch/ Adhesive Resin Cements to Dentin: An In Vitro Study

Aim: The aim of this study was to evaluate the effect of desensitizer, temporary cements, dentin cleaning methods on shear bond strength (SBS) of self-etch and self-adhesive resin cements to dentin. Materials and Methods: Four hundred eighty buccal or lingual/palatine coronal portions of human molar teeth were mounted in the acrylic blocks. Teeth surfaces were prepared until the dentin was exposed. Specimens were divided into four groups. One group separated as control and three groups of teeth were treated with a desensitizing agent containing calcium-phosphate desensitizer (Teethmate Desensitizer, TMD), resin-based self-reinforcing monomer (Shield Force Plus, SFP) and 2-hydroxyethyl methacrylate and glutaraldehyde (Gluma Desensitizer). Two different temporary cement containing calcium hydroxide (Dycall) and zinc oxide based (Rely X Temp NE) temporary cement were applied to the dentin surfaces. Temporary cement was removed with one of three cleansing techniques: 2% chlorhexidine digluconate and glass particles containing agent (Consepsis Scrub), cleansing bur (OptiClean), and ıntra/extracoronal rotary brush (Starbrush). All groups were further divided into two cementation subgroups (Panavia V5 and Panavia SA). The SBS (MPa) was measured using a universal testing machine at 0.5 mm/min crosshead speed. The data were analyzed statistically with a four-way analysis of variance and Tukey’s Honest Significant Difference test ( α = 0.05). Results: Although SFP showed higher SBS, there was no statistically significant difference between other groups ( P > .05). There were no significant differences between temporary cements ( P > .05). OptiClean rotary bur showed higher mean SBS values in all groups. The dual-polymerized Panavia V5 showed the highest SBS values in all groups ( P <.05). Conclusion: Cleaning of dentin surface from temporary cement remnants with a silicon bur and dual-cure resin cement showed the highest bond strength values.