Ensuring an accurate color match of resin composite restorations to the surrounding tooth structure is a critical aspect of any esthetic restorative procedure. A better understanding of the changes taking place during the different stages of maturation and storage of composites may be of significant benefit to clinicians as this may help minimize shade mismatch issues.

A novel chlorhexidine-containing adhesive may offer comparable dentin-resin bond stability to the use of 2.0% chlorhexidine digluconate applied as a therapeutic primer while also providing a simplified clinical application technique. SUMMARYPurpose: The present study aimed to investigate a novel adhesive system containing 0.2% chlorhexidine digluconate (CHX) for its ability to improve the stability of the adhesive interface compared with the use of 2% CHX as a therapeutic primer. Furthermore, the study aimed to confirm the inhibitory properties of these CHX concentrations (0.2% and 2.0%) on dentin matrix metalloproteinase activity by gelatin zymography.Methods: Superficial dentin substrate for bonding was obtained from 120 non-carious human molars. A conventional adhesive Peak LC Bond and a CHX-containing adhesive Peak Universal Bond were used either in combination with 35% phosphoric acid (etch-and-rinse approach) or with self-etching primer (selfetch approach) for evaluation of the variables CHX treatment (2.0% therapeutic primer and 0.2% adhesive), adhesive approach (etch-andrinse and self-etch), and storage time (24 hours and six months). A bonding jig was used to fabricate composite cylinders, which were stored for either 24 hours or six months, after which shear bond strength (SBS) was evaluated using a notched-edge testing device. A three-way analysis of variance and a Student t-test with a significance level of p,0.05 were used to analyze the data. Extracts from concentrated demineralized human dentin powder were subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis and incubated in the presence of 0.2% and 2.0% CHX.Results: No significant effect of CHX treatment, adhesive approach, storage time variables, or their interactions on mean SBS was

Clinical RelevanceThe use of reduced viscosity composites, such as flowable and pre-heated resins, as the first increment in Class II preparations, did not improve gingival margin adaptation nor did it minimize gap formation at the dentin-composite interface.

Rehabilitation of a patient with amelogenesis imperfecta (AI) from both the functional and esthetic standpoints represents a challenge. The complexity of the condition requires an interdisciplinary approach for optimal treatment outcomes. A number of treatment options have been proposed. Recently, the use of bonded restorations has gained popularity because of the many benefits associated with these materials; excellent esthetics, conservative approach, and improved wear make their use advantageous. This article describes a direct approach with resin composite restorations for the transitional treatment of an adolescent with hypoplastic AI who had not completed skeletal growth. Protection against further wear, sensitivity, and plaque accumulation while significantly enhancing the patient's esthetic appearance made this case a success. Furthermore, this article describes the use of a "Clear matrix" technique, which considerably helped simplify the placement of the bonded restorations.

Benzalkonium chloride preserves resin-dentin bonds by reducing collagen solubilization. When incorporated into adhesive blends, benzalkonium chloride provides comparable bond stability to other inhibitors and application protocols without adding more steps to the bonding sequence. SUMMARYInhibition of endogenous dentin matrix metalloproteinases (MMPs) by benzalkonium chloride (BAC) decreases collagen solubilization and may help improve resin-dentin bond stability. Objective: This study evaluated the resin-dentin bond stability of experimental adhesive blends containing BAC and the stability of dentin matrices by assessing the mass loss and collagen solubilization from dentin beams pretreated with BAC.Materials and Methods: Twenty-five healthy molars were used for the bond strength evaluation of a two-step etch-and-rinse adhesive (Adper Single Bond Plus, SB) modified with BAC or not. The following groups were tested: 1) SB with no inhibitor (control); 2) topical 2.0% chlorhexidine + SB; 3) 1.0% BAC etchant + SB; 4) 0.5% BAC-SB; and 5) 1.0% BAC-SB. Microtensile bond strength (lTBS) and failure mode distribution under standard error of the mean were evaluated after 24 hours and six months of storage in artificial saliva (AS). A two-way analysis of variance and Tukey test with a significance level of p,0.05 was used for data analysis. In addition, 30 completely demineralized dentin beams from human molars were either dipped in deionized water (DW, control) or dipped in 0.5% and 1.0% BAC for 60 seconds, and then incubated in AS. Collagen solubilization was assessed by evaluating the dry mass loss and quantifying the amount of hydroxyproline (HYP) released from hydrolyzed specimens after four weeks of incubation.Results: The control group demonstrated lower lTBS than some of the experimental groups containing BAC at 24 hours and six months (p,0.05). When BAC was incorporated into the adhesive blend in concentrations of 0.5% and *Camila Sabatini, DDS, MS, assistant professor,

Carbodiimide (EDC) and glutaraldehyde are cross-linking agents capable of increasing resin-dentin bond durability. This study showed that these substances might be safely applied on acid-etched dentin since they have no transdentinal cytotoxic effects on cultured odontoblast-like cells. SUMMARYObjective: To evaluate the transdentinal cytotoxicity of three different concentrations of carbodiimide (EDC) or 5% glutaraldehyde (GA) on MDPC-23 cells.Methods: Seventy 0.4-mm-thick dentin disks obtained from human molars were adapted to artificial pulp chambers. MDPC-23 cells were seeded on the pulpal surface of the disks. After 48 hours, the occlusal dentin was acid-etched and treated for 60 seconds with one of the Results: EDC at all test concentrations did not reduce cell viability, while 5% GA did increase cell metabolism. Cell death by necrosis was not elicited by EDC or 5% GA. At the 24-hour period, 0.3 M and 0.5 M EDC reduced TP production by 18% and 36.8%, respectively. At seven days, increased TP production was observed in all groups. Collagen production at the 24-hour period was reduced when 0.5 M EDC was used. After seven days, no difference was observed among the groups. SEM showed no alteration in cell morphology or number, except in the hydrogen peroxide group.Conclusions: Treatment of acid-etched dentin with EDC or GA did not cause transdentinal cytotoxic effects on odontoblast-like cells.

This study evaluated the effects of different concentrations of benzalkonium chloride (BAC) on the preservation of adhesive interfaces created with two etch-and-rinse adhesives and its inhibitory properties on dentin matrix metalloproteinase (MMP) activity. The following groups were tested with the adhesive systems Optibond Solo Plus and All-Bond 3: Group 1, adhesive without inhibitor (control); Group 2, topical 2.0% chlorhexidine (2.0% CHX); Group 3, phosphoric acid with 1.0%wt BAC (BAC-PA); Group 4, 0.25% BAC-adhesive (0.25% BAC); Group 5, 0.5% BAC-adhesive (0.5% BAC); Group 6, 1.0% BAC-adhesive (1.0% BAC); and Group 7, 2.0% BAC-adhesive (2.0% BAC). Composite cylinders were fabricated, and shear bond strength (SBS) was evaluated after 24 h, 6 months, and 18 months of storage. Extracts from concentrated demineralized human dentin powder were subjected to SDS-PAGE and incubated in the presence of 0.25, 0.5, 1.0, and 2.0% BAC. Overall, stable bonds were maintained for 18 months. Improved bond strengths were seen for 0.5% BAC and 1.0% BAC when bonding with Optibond Solo Plus, and for 0.25% BAC and 0.5% BAC when bonding with All-Bond 3. Zymographic analysis revealed complete inhibition of gelatinolytic activity with BAC. Benzalkonium chloride, at all concentrations, inhibited dentin proteolytic activity, which seems to have contributed to the improved bond stability after 18 months for specific combinations of BAC concentration and adhesive.

Objective:To evaluate the effect of optional phosphoric acid etching on the shear bond strength (SBS) of two self-etch adhesives to enamel and dentin.Material and Methods:Ninety-six bovine mandibular incisors were ground flat to obtain enamel and dentin substrates. A two-step self-etch adhesive (FL-Bond II) and a one-step self-etch adhesive (BeautiBond) were applied with and without a preliminary acid etching to both the enamel and dentin. The specimens were equally and randomly assigned to 4 groups per substrate (n=12) as follows: FL-Bond II etched; FL-Bond II un-etched; BeautiBond etched; BeautiBond un-etched. Composite cylinders (Filtek Z100) were bonded onto the treated tooth structure. The shear bond strength was evaluated after 24 hours of storage (37ºC, 100% humidity) with a testing machine (Ultra-tester) at a speed of 1 mm/min. The data was analyzed using a two-way ANOVA and post-hoc Tukey's test with a significance level of p<0.05. A field emission scanning electron microscope was used for the failure mode analysis.Results:Both adhesives evidenced a significant decrease in the dentin SBS with the use of an optional phosphoric acid-etching step (p<0.05). Preliminary phosphoric acid etching yielded significantly higher enamel SBS for FL-Bond II (p<0.05) only, but not for BeautiBond. FL-Bond II applied to un-etched dentin demonstrated the highest mean bond strength (37.7±3.2 MPa) and BeautiBond applied to etched dentin showed the lowest mean bond strength (18.3±6.7 MPa) among all tested groups (p<0.05).Conclusion:The use of a preliminary acid-etching step with 37.5% phosphoric acid had a significant adverse effect on the dentin bond strength of the self-etch adhesives evaluated while providing improvement on the enamel bond strength only for FL-Bond II. This suggests that the potential benefit that may be derived from an additional etching step with phosphoric acid does not justify the risk of adversely affecting the bond strength to dentin.