Clinical Comparison of Three Indirect Pulp Capping Restorative Protocols: A Randomized Controlled Prospective Study.

OBJECTIVES: The objective of this prospective double-blind clinical trial was to compare clinical outcomes of indirect pulp capping restorative protocols on permanent teeth over a 12-month period. METHODS AND MATERIALS: Deep carious lesions in permanent teeth (90) were randomly assigned to three indirect pulp capping protocols (n=30: TheraCal LC, Dycal, and no liner). All teeth were restored with resin composite. The outcome measures were pain (VAS scale) and success rate (pulp vitality based on percussion, palpation, cold test, and radiographic findings), collected at screening, intervention, and 24-hour, 7-day, 3-month, 6-month, and 12-month follow-up visits. RESULTS: There was no statistically significant difference in tooth sensitivity among the three indirect pulp capping protocols nor in success rates among the restorative protocols after 1 year of follow-up (p>0.1).The respective success rates, as defined by the tooth remaining vital, after 1 year were: 96.2% for TheraCal LC, 100% for Dycal, and 100% for no liner. CONCLUSIONS: After 12-month evaluation, the success rate of indirect pulp capping therapy on permanent teeth was not affected by the pulp capping restorative protocol.

Development and Assessment of Bioactive Coatings for the Prevention of Recurrent Caries Around Resin Composite Restorations.

OBJECTIVE: To develop hydrophilic resin-based surface coatings containing bioactive agents (proanthocyanidins from Vitis vinifera and calcium silicate) and assess their protective role at the dentin and enamel margins of cervical restorations against demineralization under simulated conditions of high and low caries activity. METHODS: Suboptimal resin composite restorations were placed on cervical cavity preparations on buccal and lingual surfaces of thirty-two molars after a contamination protocol. Groups were divided according to the resin-based coatings (n=8): resin without bioactive (C), resin containing 2% enriched Vitis Vinifera (VVE), and resin coat containing 10% calcium silicate (CaSi). The control group did not receive a resin (NC). To simulate a hydrolyticenzymatic degradation, specimens were subjected to 2-month storage followed by incubation in esterase at 37°C for 8 days. Afterwards, recurrent caries was induced using a pH-proteolytic model on half of the specimens to simulate high caries activity, and the other half remained in simulated body fluid (SBF). Measurements of cross-section microhardness (KHN) and infiltration with rhodamine-B assessed the micropermeability (MP), the extent of demineralization (ED), and the demineralization area (DA). Data were analyzed using analysis of variance (ANOVA) and post-hoc tests (α=0.05). RESULTS: VVE and CaSi presented higher cross-sectional KHN values for enamel and dentin (p<0.001). The bioactive coatings resulted in lower MP, ED, and DA compared to NC (p<0.005) in enamel and dentin. CaSi coating preserved the enamel from demineralization (p=0.160). CONCLUSION: The application of bioactive coatings represents a potential strategy to protect the enamel-dentin margins of resin restorations.

Dimeric Proanthocyanidins on the Stability of Dentin and Adhesive Biointerfaces.

A dentin biomodification strategy with selective proanthocyanidin (PAC)-enriched extracts reinforces dentin and dentin-resin interfaces. Enrichment of the extracts according to the degree of polymerization allows exploration of bioactive principles of PACs and structure-activity relationships. This study investigated the sustained dentin matrix biomodification and dentin-resin bioadhesion of 2 fractions consisting exclusively of B-type PAC dimers with or without a single galloyl motif (specifically, DIMERG and DIMERNG) and their precursor material, enriched grape seed extract (e-GSE; Vitis vinifera). The biomodification potential was determined by long-term evaluation of the apparent modulus of elasticity and collagen solubility (hydroxyproline release). Chemical characterization of the dentin matrix was performed by attenuated total reflectance-Fourier-transform infrared spectroscopy. The bioadhesive properties were assessed by a microtensile bond strength test at different time points, and macro-hybrid layers were produced to verify the degree of conversion of the adhesive resin. Fractions consisting of DIMERG, DIMERNG, and their precursor, e-GSE, increased the modulus of elasticity at all time points and reduced collagen degradation. Specimens treated with DIMERNG remained stable throughout 12 mo of storage, whereas a significant drop in the modulus of elasticity was observed for the DIMERG and e-GSE groups at 6 mo. The fractions and precursor did not affect the degree of resin conversion at the hybrid layer. Changes in infrared resonances corresponding to collagen cross-links in the dentin matrix occurred for all treatments. Higher bond strength was observed for dentin treated with e-GSE as compared with DIMERG and DIMERNG; all biointerfaces remained stable after 12 mo. Nongalloylated PACs mediate stable dentin biomodification, which includes protective activity against collagen degradation and reinforcement of the anchoring dentin matrix. Collectively, PACs with a higher degree of oligomerization offer a robust bioadhesion between the hydrophilic dentin matrix and the hydrophobic adhesive.

Direct and transdentinal biostimulatory effects of grape seed extract rich in proanthocyanidin on pulp cells.

AIM: To evaluate the potential biostimulatory effects of grape seed extract (GSE) on a primary culture of human pulp cells. METHODOLOGY: Human molars were used to obtain the primary pulp cell culture and 0.5-mm dentine discs. For GSE direct exposure, dose-response (0.0065-6.5%) and time response (1-60 min of contact) were examined. For transdentinal exposure, 0.65% of GSE was tested for 24 h. Cellular metabolism, nitric oxide and collagen production, and cell morphology alterations were assessed at periods of 24 and 72 h. After cell differentiation and direct exposure to GSE, the total protein production (TP), alkaline phosphatase activity (ALP) and formation of mineralization nodules (MN) were assessed. The results were analysed by parametric tests or non-parametric tests (α = 0.05). RESULTS: The lower concentration of GSE tested (0.0065%) was associated with an increase in cellular metabolism, a reduction in the production of nitric oxide and an increase in extracellular matrix synthesis (collagen). Distinct behaviours were observed for the different concentrations, without a reduction of cellular metabolism >10% compared with the control, either when applied directly or transdentinally. SEM revealed no significant change in cell morphology, except for the positive control (H2 O2 ). There was no difference in TP, ALP or MN between the control group and the group exposed to GSE. CONCLUSIONS: Treatment with grape seed extract, even at the highest concentration and longest period, caused neither direct nor transdentinal cytotoxic effects on human pulp cells. Grape seed extract components may play a biostimulatory role and protect dental pulp cells when in direct contact.

Long-term evaluation of the stability of dentin matrix following treatments with aqueous solutions of titanium tetrafluoride at different concentrations.

OBJECTIVE: The purpose of this study was to investigate the effects of aqueous solutions of different concentrations of titanium tetrafluoride (TiF4) on dentin matrix stability up to six months. DESIGN: Dentin specimens prepared from fifteen nonerupted molars were demineralized and randomly distributed into groups: 2.5% TiF4, 4% TiF4, 1000 ppm NaF, and control (distilled water). The modulus of elasticity (ME) and dry masses of the dentin matrix were determined at baseline, and up to 6 months following treatment. Collagen solubilization was estimated by hydroxyproline (HYP) quantification in the simulated body fluid used to store the dentin specimens. RESULTS: The 2.5% TiF4 group presented higher ME immediately after treatment, and at 3 and 6 months storage, whereas 4% TiF4 showed higher means at 3 and 6 months (p < 0.001). No significant differences were observed among the groups over time (p = 0.9325). However, the 2.5% TiF4 group showed significantly higher ME than the control group, immediately after treatment. All the groups presented significantly higher mass change immediately, compared with 3 and 6 months (p < 0.0001). Except for the 4% TiF4 group, HYP release was higher in the first quarter (p = 0.0152), when no significant differences were found among the groups. In the second quarter, the means were significantly higher in the 2.5% TiF4 and 4% TiF4 groups. The group treated with 2.5% TiF4 had a statistically higher HYP release than the control group. CONCLUSION: An aqueous solution of 2.5% TiF4 increases the immediate stiffness values, but does not stabilize the collagenous dentin matrix.

A Novel Enamel and Dentin Etching Protocol Using α-hydroxy Glycolic Acid: Surface Property, Etching Pattern, and Bond Strength Studies.

OBJECTIVES: To determine the use of α-hydroxy glycolic acid (GA) as a surface pretreatment for dental restorative applications. The etching pattern of GA pretreatment of dental hard tissues was assessed by surface microhardness and scanning electron microscopy (SEM). The effectiveness of GA surface etching on the enamel and dentin resin bond strengths was assessed using two etchant application modes (rubbing and no rubbing) and three adhesive systems (Single Bond [SB], One Step Plus [OSP], and Scotchbond Universal [SBU]). METHODS: Knoop microhardness measurements were carried out on polished enamel and dentin surfaces before and after treatment with 35% GA, 35% phosphoric acid (PA), or distilled water (control group) for 30 seconds. The microtensile bond strength test was carried out on enamel and dentin. Ultrastructural analysis of the surface and interfacial interaction was qualitatively accomplished using SEM. RESULTS: Etching with either PA or GA significantly decreased the enamel microhardness, with GA being significantly less aggressive than PA ( p<0.001), while both acids showed similar decreases in dentin microhardness ( p=0.810). SEM revealed similar etching patterns of GA and PA, while apparently a thinner hybrid layer was observed for GA groups. In dentin, the bond strengths were statistically similar between PA and GA groups, regardless of the etchant application mode ( p>0.05). However, rubbing of GA enhanced the bond strength to enamel. PA and GA significantly increased the SBU bond strength to enamel when compared to SB and OSP ( p<0.05). CONCLUSIONS: GA effectively etched enamel and dentin surfaces, resulting in bond strength values similar to those associated with traditional PA. GA is a suitable enamel and dentin surface etchant for adhesive restorative procedures.

Biostability of the Proanthocyanidins-Dentin Complex and Adhesion Studies.

Oligomeric proanthocyanidins (OPACs) are potent and renewable natural bioactives possible to be refined into chemically standardized mixtures for biological applications. Herein, we found that multiscale interactions of OPACs with the dentin matrix create tight biointerfaces with hydrophobic methacrylate adhesives on wet surfaces. An enriched mixture of OPACs, with a known phytochemical profile, was produced from grape seed crude extract ( Vitis vinifera; enriched grape seed extract [e-GSE]) and applied to dentin matrices to determine changes to the mechanical properties and biodegradability of the dentin matrix and favorable resin adhesion mechanisms. Methods included a 3-point flexural test, quantification of hydroxyproline (collagen solubilization), static and dynamic nanomechanical analyses, resin-dentin microtensile bond strength, and micropermeability at the adhesive interface. The e-GSE-modified dentin matrix exhibited remarkably low collagen solubilization and sustained the bulk elastic properties over 12 mo. Tan δ findings reveal a more elastic-like behavior of the e-GSE-modified dentin matrix, which was not affected by H-bond destabilization by urea. Dentin-methacrylate biointerfaces with robust and stable adhesion were created on e-GSE-primed dentin surfaces, leading to a dramatic decrease of the interfacial permeability. Standardized OPAC mixtures provide a new mechanism of adhesion to type I collagen-rich tissues that does not rely on hydrophilic monomers. The bioadhesion mechanism involves physicochemical modifications to the dentin matrix, reduced tissue biodegradation, and bridging to methacrylate resins.

Immunolocalization and distribution of proteoglycans in carious dentine.

BACKGROUND: Collagen type I, proteoglycans (PG) and non-collagenous proteins represent important building blocks of the dentine matrix. While different PGs have been identified in dentine, changes in the distribution of these macromolecules with the progression of caries have been poorly characterized. The aim of this study was to compare the immunolocalization of three small collagen-binding PGs (biglycan, fibromodulin and lumican) as well as collagen (types I and VI) in healthy versus carious dentine. METHODS: Longitudinal demineralized sections of extracted teeth were stained with antibodies recognizing specific PG core proteins and collagens, as well as glycosaminoglycans (GAGs) with toluidine blue. RESULTS: In healthy dentine, PGs appeared to be more abundant near the tubule walls and directly under the cusps. Conversely, in carious dentine, specific locations appeared to be more prone to PG degradation than others. These degradation patterns were well correlated with the progression of caries into the tissue, and also appeared to trigger interesting morphological changes in the tissue structure, such as the deformation of dentine tubules near highly infected areas and the lower concentration of PG in tertiary dentine. CONCLUSIONS: This study presents new insights into the involvement of PGs in the progression of caries.

DMP1-derived peptides promote remineralization of human dentin.

Remineralization of dentin during dental caries is of considerable clinical interest. Dentin matrix protein 1 (DMP1) is a non-collagenous calcium-binding protein that plays a critical role in biomineralization. In the present study, we tested if peptides derived from DMP1 can be used for dentin remineralization. Peptide pA (pA, MW = 1.726 kDa) and peptide pB (pB, MW = 2.185), containing common collagen-binding domains and unique calcium-binding domains, were synthesized by solid-phase chemistry. An extreme caries lesion scenario was created by collagenase digestion, and the biomineral-nucleating potential of these peptides was ascertained when coated on collagenase-treated dentin matrix and control, native human dentin matrix under physiological levels of calcium and phosphate. Scanning electron microscopy analysis suggests that peptide pB was an effective nucleator when compared with pA. However, a 1:4 ratio of pA to pB was determined to be ideal for dentin remineralization, based on hydroxyapatite (HA) morphology and calcium/phosphorus ratios. Interestingly, HA was nucleated on collagenase-challenged dentin with as little as 20 min of 1:4 peptide incubation. Electron diffraction confirmed the presence of large HA crystals that produced a diffraction pattern indicative of a rod-like crystal structure. These findings suggest that DMP1-derived peptides may be useful to modulate mineral deposition and subsequent formation of HA when exposed to physiological concentrations of calcium and phosphate.

Dentin biomodification potential depends on polyphenol source.

Although proanthocyanidins (PACs) modify dentin, the effectiveness of different PAC sources and the correlation with their specific chemical composition are still unknown. This study describes the chemical profiling of natural PAC-rich extracts from 7 plants using ultra high pressure/performance liquid chromatography (UHPLC) to determine the overall composition of these extracts and, in parallel, comprehensively evaluate their effect on dentin properties. The total polyphenol content of the extracts was determined (as gallic acid equivalents) using Folin-Ciocalteau assays. Dentin biomodification was assessed by the modulus of elasticity, mass change, and resistance to enzymatic biodegradation. Extracts with a high polyphenol and PAC content from Vitis vinifera, Theobroma cacao, Camellia sinensis, and Pinus massoniana induced a significant increase in modulus of elasticity and mass. The UHPLC analysis showed the presence of multiple types of polyphenols, ranging from simple phenolic acids to oligomeric PACs and highly condensed tannins. Protective effect against enzymatic degradation was observed for all experimental groups; however, statistically significant differences were observed between plant extracts. The findings provide clear evidence that the dentin bioactivities of PACs are source dependent, resulting from a combination of concentration and specific chemical constitution of the complex PAC mixtures.

Biomimetic approach for root caries prevention using a proanthocyanidin-rich agent.

The aim of this study was to evaluate the effects of a proanthocyanidin-rich grape seed extract (GSE) on the in vitro demineralization of root dentine. Root fragments were obtained from sound human teeth. The fragments were randomly assigned to different treatments solutions: GSE, fluoride (F), GSE+F and distilled water (control). Samples were treated daily for 30 min and subjected to a pH cycling artificial caries protocol using demineralization cycles (2.2 mM CaCl(2)×H(2)O, 2.2 mM KH(2)PO(4), 50 mM acetic acid, pH 4.3) for 6 h and remineralization cycles (20 mM HEPES, 2.25 mM CaCl(2)×H(2)O, 1.35 mM KH(2)PO(4), 130 mM KCl, pH 7.0) for 17.5 h. Mineral loss (ΔZ) and lesion depth (LD) were determined after 18 days of treatment/pH cycling, by transverse microradiography. GSE was able to minimize ΔZ and LD compared with the control group (p < 0.0001). The GSE+F and F groups showed the lowest values of ΔZ and LD (p < 0.05), with no statistically significant differences between them (p = 0.554 and p = 0.726, respectively). A biomimetic approach to strengthen root dentine using GSE results in decreased rates of root demineralization and may be used in conjunction with F to prevent root caries.

Nanomechanical properties of biochemically modified dentin bonded interfaces.

The effect of biomodification of dentin matrices using collagen cross-linkers, glutaraldehyde (GD) and grape seed extract (GSE), on the reduced modulus of elasticity (Er) and nanohardness (H) of the hybrid layer and underlying dentin was investigated at the dentin-resin bonded interface. The coronal dentin of nine molars were exposed and divided into groups: 5% GD, 6·5% GSE and control. Control samples were etched, bonded with Adper Single Bond Plus and Premise composite. GD and GSE were applied for 1 h prior to bonding procedures. After 24 h, samples were sectioned, and resin-dentin beams were either kept in distilled water or exposed to collagenase treatment for 24 h. Nano-indentations were performed at the hybrid layer and underlying dentin. GD and GSE treatment increased the Er and H of resin-dentin interface structures when compared to the control group (P<0·05), particularly the hybrid layer, and may be a promising novel approach to strengthen the dentin-resin bonded interface structures when using these adhesive system and resin-based composite.

Effects of chemical cross-linkers on caries-affected dentin bonding.

The achievement of a strong and stable bond between composite resin and dentin remains a challenge in restorative dentistry. Over the past two decades, dental materials have been substantially improved, with better handling and bonding characteristics. However, little attention has been paid to the contribution of collagen structure/stability to bond strength. We hypothesized that the induction of cross-linking in dentin collagen improves dentin collagen stability and bond strength. This study investigated the effects of glutaraldehyde-and grape seed extract-induced cross-linking on the dentin bond strengths of sound and caries-affected dentin, and on the stability of dentin collagen. Our results demonstrated that the application of chemical cross-linking agents to etched dentin prior to bonding procedures significantly enhanced the dentin bond strengths of caries-affected and sound dentin. Glutaraldehyde and grape seed extract significantly increased dentin collagen stability in sound and caries-affected dentin, likely via distinct mechanisms.

Mechanical properties of tannic-acid-treated dentin matrix.

Dentin collagen is a major component of the hybrid layer, and its stability may have a great impact on the properties of adhesive interfaces. We tested the hypothesis that the use of tannic acid (TA), a collagen cross-linking agent, may affect the mechanical properties and stability of the dentin matrix. The present study evaluated the effects of different concentrations of TA on the modulus of elasticity and enzymatic degradation of dentin matrix. Hence, the effect of TA pre-treatment on resin-dentin bond strength was assessed with the use of two bonding systems. Sound human molars were used and prepared according to each experimental design. The use of TA affected the properties of demineralized dentin by increasing its stiffness. TA treatment inhibited the effect of collagenase digestion on dentin matrix, particularly for 10%TA and 20%TA. The TA-dentin matrix complex resulted in improved bond strength for both adhesive systems.

Interfacial ultramorphology of single-step adhesives: nanoleakage as a function of time.

The aim of this study was to examine the effectiveness of single-step self-etching adhesives in preventing nanoleakage over a 90-day water-storage period, and analyse the ultramorphological characteristics of resin-dentin interfaces. Three single-step self-etching adhesives were evaluated: Adper Prompt L-Pop - LP (3M ESPE), iBond - iB (Heraeus Kulzer), and Clearfil Tri-S Bond - S3 (Kuraray). Bonded specimens were sectioned into 0.9-mm thick slabs and stored in water for 1, 60 or 90 days. After the storage periods, a silver tracer solution was used to reveal nanometer-sized spaces and evidence of degradation within resin-dentin interfaces. Epoxy resin-embedded sections were prepared, and the interfaces observed with the TEM. Nanoleakage patterns were compared among adhesives and storage periods using image analysis software. Data were statistically analysed by two-way anova and Tukey test. Nanoleakage was observed in all resin-dentin interfaces produced by the single-step self-etching adhesives. Results showed that LP presented the lowest silver deposition means at 1 day. However, after 60 and 90 days, the area of silver deposition significantly increased for LP. iB presented intense silver deposition after 1 day and a small increase after 90 days. S3 presented the lowest silver deposition means after 60 and 90 days of water-storage.