Dj Epasinghe

Effect of proanthocyanidin incorporation into dental adhesive resin on resin–dentine bond strength

OBJECTIVES This study evaluated the effect of proanthocyanidin (PA) incorporation into experimental dental adhesives on resin-dentine bond strength. METHODS Four experimental hydrophilic adhesives containing different PA concentrations were prepared by combining 50wt% resin comonomer mixtures with 50wt% ethanol. Proanthocyanidin was added to the ethanol-solvated resin to yield three adhesives with PA concentrations of 1.0, 2.0 and 3.0wt%, respectively. A PA-free adhesive served as the control. Flat dentine surfaces from 40 extracted third molars were etched with 32% phosphoric acid. The specimens were randomly assigned to one of the four adhesive groups. Two layers of one of the four experimental adhesives were applied to the etched dentine and light-cured for 20s. Composite build-ups were performed using Filtek Z250 (3M ESPE). After storage in distilled water at 37°C for 24h, twenty-four bonded teeth were sectioned into 0.9 mm×0.9 mm beams and stressed to failure under tension for bond strength testing. Bond strength data were evaluated by one-way ANOVA and Tukeys test (α=0.05). Interfacial nanoleakage was examined in the remaining teeth using a field-emission scanning electron microscope and analysed using the Chi-square test (α=0.05). RESULTS No significant difference in bond strength was found amongst PA-free, 1% and 2% PA adhesives. However, incorporation of 3% PA into the adhesive significantly lowered bond strength as demonstrated by a greater number of adhesive failures and more extensive nanoleakage along the bonded interface. CONCLUSION Incorporation of 2% proanthocyanidin into dental adhesives has no adverse effect on dentine bond strength. CLINICAL SIGNIFICANCE The addition of proanthocyanidin to an experimental adhesive has no adverse effect on the immediate resin-dentine bond strength when the concentration of proanthocyanidin in the adhesive is less than or equal to 2%.

The inhibitory effect of proanthocyanidin on soluble and collagen-bound proteases.

OBJECTIVE This study evaluated the inhibitory effect of proanthocyanidin (PA), a natural collagen cross-linker, on soluble and matrix-bound proteases, which are responsible for progressive degradation of exposed collagen fibrils within the hybrid layer and resin-dentine bond failure over time. METHODS The inhibitory effects of PA (1%, 2%, 3%, 4.5% and 6%) on soluble recombinant matrix metalloproteinases (MMP-2, -8 and -9) and cysteine cathepsins (cathepsin B and K) were evaluated using MMP and cysteine cathepsins fluorometric assay kits. Chlorhexidine (CHX) was used as an inhibitor control. The effect of PA on endogenous matrix-bound proteases was examined by determining the change in dry mass of demineralized dentine beams and solubilized collagen peptides over 30 days. Two-way ANOVA and Tukey multiple comparison tests were used to analyze the effect of PA and proteases on the percentage inhibition of soluble proteases (α=0.05). Kruskal-Wallis one-way ANOVA and Dunns multiple comparison tests were used to analyse the effect of PA on loss of dry mass and hydroxyproline content over time (α=0.05). RESULTS Proanthocyanidin inactivated more than 90% of soluble recombinant MMP-2, -8 and -9 and around 75-90% of cysteine cathepsin B and K, which was significantly higher than CHX (P<0.05). The inhibition of endogenous proteases by PA increased in a dose-dependent manner. The loss of dry mass and hydroxyproline release in the medium over time was the lowest in dentine beams pretreated with PA

Effect of flavonoids on the mechanical properties of demineralised dentine

OBJECTIVES This study compared the effect of three flavonoids: proanthocyanidin, naringin and quercetin on the modulus of elasticity (MOE) and ultimate tensile strength (UTS) of demineralised dentine. METHODS Thirty teeth were sectioned into 0.5mm×1.7mm×7mm beams for MOE measurement. Another 30 non-carious molars were sectioned into 0.5mm×0.5mm thick dentine beams for UTS testing. Demineralised specimens were divided into three groups according to treatments: 6.5% proanthocyanidin, 6.5% quercetin and 6.5% naringin. Specimens were kept in their respective solutions and tested at baseline, 10min, 30min, 1h and 4h. The MOE of each specimen was determined using a three-point bending test at a crosshead speed of 0.5mm/min. For UTS evaluation, each specimen was tested in tension until failure using a crosshead speed of 1mm/min. Means and standard deviation were calculated. Two-way ANOVA and Tukey test were used to evaluate the effect of flavonoid treatment and treatment duration on MOE and UTS. RESULTS Both MOE and UTS were significantly affected by flavonoid treatment (p<0.001) and treatment duration (p<0.001). Interaction of the two factors was significant for MOE (p<0.001), but not for UTS (p>0.05). Flavonoid treatment improved the mechanical properties of demineralised dentine in the order: proanthocyanidin>quercetin>naringin. It took a longer time for the flavonoids to produce a significant change in UTS, when compared to MOE. CONCLUSION Proanthocyanidin was more effective than quercetin and naringin in improving biomechanical properties of dentine matrix, thereby enhancing preventive and reparative dental therapies. CLINICAL SIGNIFICANCE Despite its larger molecular size, proanthocyanidin was more effective than quercetin and naringin, in enhancing the biomechanical properties of demineralised dentine.

Altered tooth morphogenesis after silencing the planar cell polarity core component, Vangl2

Vangl2, one of the core components of the planar cell polarity (PCP) pathway, has an important role in the regulation of morphogenesis in several tissues. Although the expression of Vangl2 has been detected in the developing tooth, its role in tooth morphogenesis is not known. In this study, we show that Vangl2 is expressed in the inner dental epithelium (IDE) and in the secondary enamel knots (SEKs) of bell stage tooth germs. Inhibition of Vangl2 expression by siRNA treatment in in vitro-cultured tooth germs resulted in retarded tooth germ growth with deregulated cell proliferation and apoptosis. After kidney transplantation of Vangl2 siRNA-treated tooth germs, teeth were observed to be small and malformed. We also show that Vangl2 is required to maintain the proper pattern of cell alignment in SEKs, which maybe important for the function of SEKs as signaling centers. These results suggest that Vangl2 plays an important role in the morphogenesis of teeth.

Synergistic effects of proanthocyanidin, tri-calcium phosphate and fluoride on artificial root caries and dentine collagen

BACKGROUND Proanthocyanidin has been shown to enhance dentine collagen stability and remineralization of artificial root caries. OBJECTIVES To evaluate the effect of proanthocyanidin (PA) in combination with tri-calcium phosphate (TCP) and fluoride (F) on resistance to collagen degradation and remineralization of artificial caries lesions. METHODS Demineralized root fragments (n=75) were randomly divided into five groups based on treatments: (i) 6.5% PA, (ii) TCP+F, (iii) TCP+F+6.5% PA, (iv) 1000ppm fluoride (Positive control) and (v) deionized water (control). Each specimen was subjected to pH cycling at 37o C for 8days. Lesion depth and mineral loss were evaluated using microradiography and confocal laser scanning microscopy. The type of crystal formation was determined by XRD spectra. To evaluate the stability of root caries lesions against collagenase challenge, highly purified type VII collagenase from Clostridium was added to obtain a remineralizing solution that contained 7.5U/mL collagenase and pH cycling was repeated. The different remineralizing solutions were collected after the pH cycling to assess the amount of hydroxyproline release. Collagen degradation depth and lesion depth were evaluated using transverse microradiography. Resistance to collagen degradation was determined using hydroxyproline assay. Data were analyzed using one-way ANOVA and Tukey multiple comparison tests. RESULTS Results of one-way ANOVA showed that the test solutions had a significant effect on mineral loss (p<0.001) and lesion depth (p<0.001) of artificial root caries. The lowest lesion depth and mineral loss were observed in the TCP+F+PA (p<0.05) group. The XRD patterns showed hydroxyapatite formation on TCP+F-treated artificial caries lesions, which were not altered by the addition of PA. The addition of PA to TCP+F significantly reduced collagen degradation depth, when compared to TCP only group (p<0.001). Lesion depth was the lowest in the PA and TCP+F+PA groups following collagenase degradation (p<0.001). The addition of PA to TCP+F also decreased hydroxyproline release, when compared to TCP+F group (p<0.001). CONCLUSION The addition of PA to TCP+F reduced collagen degradation, inhibited demineralization and enhanced remineralization.

Comparison of biofilm formation and migration of Streptococcus mutans on tooth roots and titanium miniscrews

Periodontitis and peri‐implantitis are inflammatory diseases caused by periodontal pathogenic bacteria leading to destruction of supporting periodontal/peri‐implant tissue. However, the progression of inflammatory process of these two diseases is different. The bacterial biofilm is the source of bacteria during the inflammatory process. As the bacteria migrate down the surface of tooth or titanium implant, the inflammation spreads along with it. Streptococcus mutans has an important role in oral bacterial biofilm formation in early stage biofilm before the microbiota shift to late stage and become more virulent. The other major difference is the existence of periodontal ligament (PDL) cells in normal teeth but not in peri‐implant tissue. This study aims to compare the S. mutans bacterial biofilm formation and migration on 2 different surfaces, tooth root and titanium miniscrew. The biofilm was grown with a flow cells system to imitate the oral dynamic system with PDL cells. The migration distances were measured, and the biofilm morphology was observed. Data showed that the biofilm formation on miniscrew was slower than those on tooth root at 24 hr. However, there were no difference in the morphology of the biofilm formed on the tooth root with those formed on the miniscrew at both 24 and 48 hr. The biofilm migration rate was significantly faster on miniscrew surface compare with those on tooth root when observe at 48 hr (p < .001). There are no significant differences in biofilm migration within miniscrew group and tooth root group despite the exiting of PDL cell (p > .05). The biofilms migration rate differences on various surfaces could be one of the factors accounting for the different inflammatory progression between periodontitis and peri‐implantitis disease.

Effect of proanthocyanidin on ultrastructure and mineralization of dentine collagen

OBJECTIVE Proanthocyanidin (PA) is a natural collagen cross-linker that has been used in dentine matrix biomodification for reparative and preventive therapies. This study evaluated the ultrastructure of collagen after its interaction with PA. Furthermore, the mineralization of PA-biomodified collagen matrix was observed. METHODS Ten freshly extracted sound human molars were sectioned into 0.5mm×1.7mm×7mm beams for ultrastructural evaluation of PA and dentine matrix under Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM). Specimens for TEM were completely demineralized and divided into three groups according to PA treatments: deionized water, 2% PA and 6.5% PA. The specimens were fixed, dehydrated, sectioned and examined using TEM. Specimens for FESEM were lightly conditioned with EDTA and similarly divided into the three groups for observation using FESEM. Type I collagen from calf skin was used to analyse the mineral interaction after treatment with 6.5% PA. Formvar- and carbon-coated 400-mesh Ni grids (EMS, Hatfiels, PA, USA) were placed over a 2mg/mL collagen solution prepared from calf skin-derived Type I collagen to achieve self-assembly of collagen fibrils. Grids were treated with 6.5% PA and divided into two groups. One group was floated over a remineralization solution containing 20mM HEPES, 2.25mM CaCl2-2H2O, 1.35mM KH2PO4, 3.08mM NaN3 and 130mM KCl and the other group was over a CPP-ACP solution (Tooth mousse 1:100 dilution with deionized water). The floating samples were kept in a 37°C and 100% humidity chamber. Grids were taken out at selected time durations (24h, 48h and 72h for mineralization solution/24h for CPP-ACP) and observed under TEM without staining. Selected area electron diffractions (SAEDs) were performed at 110kV. RESULTS Following treatment of demineralized dentine collagen matrix with PA, the size and number of interfibrillar spaces were reduced. The collagen fibrils aggregated together with a reduction in porosity. A characteristic banding pattern of collagen fibrils was observed under TEM. Treatment of PA-biomodified collagen fibrils with remineralization solution increased mineral aggregation along its long axis, when compared to the control group. Furthermore, treatment of PA-biomodified collagen fibrils with CPP-ACP solution enhanced mineral uptake and deposition as well as initiated apatite formation within 24h. CONCLUSION Proanthocyanidin alters the ultrastructure of demineralized dentine collagen matrix. The PA-biomodified collagen matrix promotes remineralization.

Anti-collagenolytic activity of proanthocyanidin

This journal suppl. is the Special Issue: Abstracts of the 2012 FDI Annual World Dental Congress

Effect of benzalkonium chloride applicationon resin-dentine bond strength

Introduction: Canine auto-transplantation is a surgical procedure applied in cases of ankylosed or severely displaced impacted canines. This study describes the transplantation method, as well as clinical cases where surgical intervention helped continue and complete orthodontic treatment. Case presentation: Two patients with history of surgical exposure and failure of managing impacted canines with orthodontic traction only, are presented. The successfully autogenous transplantation of the impacted teeth is demonstrated. Discussion: Literature review shows that canine auto-transplantation has, with minor variations, a wide range of applications and is almost always accompanied by or forms a part of comprehensive orthodontic treatment. It offers an alternative solution for managing complications and provides long-term stability. Method selection should be performed following thorough diagnosis taking into consideration the extent of surgical intervention necessary. Conclusion: Surgical transplantation of impacted canines constitutes a good treatment alternative with long-term stability for management of complications during settlement of impacted canines in the dental arch. If the method is to be applied instead of the usual procedure used for impacted canines, it should be performed selectively and in cases where the conventional method including surgical exposure and orthodontic traction has failed. Modern diagnostic radiographic methods play a major role in correct decision-making.Free Special Issue: Abstracts of the 23rd Congress of the International Association of Paediatric Dentistry