Substance P regulates the expression of matrix metalloproteinases and tissue inhibitors of metalloproteinase in cultured human gingival fibroblasts

Background and Objective: Substance P may play a role in the pathogenesis of periodontal disease; however, its mechanisms of modulation are not clear. This study evaluated the effect of two concentrations of Substance P on the expression of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) in cultured human gingival fibroblasts. Materials and Methods: Fibroblasts were stimulated for 48 h with 10(-4) or 10(-9) m Substance P; untreated fibroblasts served as controls. The expression of MMP-1, -2, -3, -7 and -11 and of TIMP-1 and -2 was evaluated using real-time polymerase chain reaction and western blotting. Resulsts: There was a significant, concentration-dependent stimulatory effect of Substance P on MMP-1, -2, -3 and -7 and TIMP-2 gene expression (p < 0.05), and a probable effect on MMP-11 (p = 0.06). At the higher concentration (10(-4) m Substance P), MMP-1, -2, -3, -7 and -11 and TIMP-2 showed the greatest up-regulation; at the lower concentration (10(-9) (M) Substance P), MMP-1, -3 and -7 and TIMP-2 exhibited diminished up-regulation, with MMP-2 and -11 showing down-regulation (p < 0.05). Expression of TIMP-1 was not affected by Substance P (p > 0.05). Western blotting confirmed that Substance P up-regulated MMP-1, -2, -3 and -11 and TIMP-2. MMP-1, -3 and -11 and TIMP-2 showed greater up-regulation at the higher Substance P concentration and diminished up-regulation at the lower concentration. MMP-2 was up-regulated to a similar degree at both Substance P concentrations. Conclusion: In gingival fibroblast cells, Substance P at the higher concentration (10(-4) m) induced greater up-regulation of MMP-1, -3 and -11 and TIMP-2 expression, but at the lower concentration (10(-9) (M)) induced diminished up-regulation, which may represent a mechanism for modulating periodontal breakdown.

Long-term stability of dentin matrix following treatment with various natural collagen cross-linkers

Objectives: Collagen disorganization is one of the main degradation patterns found in unsuccessful adhesive restorations. The hypothesis of this study was that pretreatment using natural collagen cross-linking agents rich in proanthocyanidin (PA) would improve mechanical properties and stability over time of the dentin collagen and, thus, confer a more resistant and lasting substrate for adhesive restorations. Methods: PA-based extracts, from grape seed (GSE), cocoa seed (CSE), cranberry (CRE), cinnamon (CNE) and acai berry (ACE) were applied over the demineralized dentin. The apparent elastic modulus (E) of the treated dentin collagen was analyzed over a 12 month period. Specimens were immersed in the respective solution and E values were obtained by a micro-flexural test at baseline, 10, 30, 60, 120 and 240 min. Samples were stored in artificial saliva and re-tested after 3, 6 and 12 months. Data was analyzed using ANOVA and Tukey test. Results: GSE and CSE extracts showed a time-dependent effect and were able to improve [240 min (MPa): GSE = 108.96 +/- 56.08: CSE = 59.21 +/- 24.87] and stabilize the E of the organic matrix [12 months (MPa): GSE = 40.91 +/- 19.69; CSE = 42.11 +/- 13.46]. CRE and CNE extracts were able to maintain the E of collagen matrices constant over 12 months [CRE = 11.17 +/- 7.22; CNE = 9.96 +/- 6.11; MPa]. ACE (2.64 +/- 1.22 MPa) and control groups immersed in neat distilled water (1.37 +/- 0.69 MPa) and ethanol-water (0.95 +/- 0.33 MPa) showed no effect over dentin organic matrix and enable their degradation and reduction of mechanical properties. Significance: Some PA-based extracts were capable of improving and stabilizing collagen matrices through exogenous cross-links induction. (C) 2011 Elsevier Ltd. All rights reserved.

Mechanical characterization of proanthocyanidindentin matrix interaction

Objectives To characterize the properties of dentin matrix treated with two proanthocyanidin rich cross-linking agents and their effect on dentin bonded interfaces. Methods Sound human molars were cut into 0.5mm thick dentin slabs, demineralized and either treated with one of two cross-linking agents (grape seedGSE and cocoa seedCOE extracts) or left untreated. The modulus of elasticity of demineralized dentin was assessed after 10 or 60min and the swelling ratio after 60min treatment. Bacterial collagenase was also used to assess resistance to enzymatic degradation of samples subjected to ultimate tensile strength. The effect of GSE or COE on the resindentin bond strength was evaluated after 10 or 60min of exposure time. Data were statistically analyzed at a 95% confidence interval. Results Both cross-linkers increased the elastic modulus of demineralized dentin as exposure time increased. Swelling ratio was lower for treated samples when compared to control groups. No statistically significant changes to the UTS indicate that collagenase had no effect on dentin matrix treated with either GSE or COE. Resindentin bonds significantly increased following treatment with GSE regardless of the application time or adhesive system used. Significance Increased mechanical properties and stability of dentin matrix can be achieved by the use of PA-rich collagen cross-linkers most likely due to the formation of a PAcollagen complex. The short term resindentin bonds can be improved after 10min dentin treatment.(C) 2010 Academy of Denta lMaterials. Published by Elsevier Ltd. All rights reserved.

Effect of argon purity on mechanical properties, microstructure and fracture mode of commercially pure (cp) Ti and Ti-6Al-4V alloys for ceramometal dental prostheses

Provision of an inert gas atmosphere with high-purity argon gas is recommended for preventing titanium castings from contamination although the effects of the level of argon purity on the mechanical properties and the clinical performance of Ti castings have not yet been investigated. The purpose of this study was to evaluate the effect of argon purity on the mechanical properties and microstructure of commercially pure (cp) Ti and Ti-6Al-4V alloys. The castings were made using either high-purity and/or industrial argon gas. The ultimate tensile strength (UTS), proportional limit (PL), elongation (EL) and microhardness (VHN) at different depths were evaluated. The microstructure of the alloys was also revealed and the fracture mode was analyzed by scanning electron microscopy. The data from the mechanical tests and hardness were subjected to a two-and three-way ANOVA and Tukey`s test (alpha = 0.05). The mean values of mechanical properties were not affected by the argon gas purity. Higher UTS, PL and VHN, and lower EL were observed for Ti-6Al-4V. The microhardness was not influenced by the argon gas purity. The industrial argon gas can be used to cast cp Ti and Ti-6Al-4V.

Effect of supplementation of soft drinks with green tea extract on their erosive potential against dentine

Background: Matrix metalloproteinase (MMP) inhibitors reduce dentine erosion. This in vitro study evaluated the effect of the supplementation of soft drinks with green tea extract, a natural inhibitor of MMPs, on their erosive potential against dentine. Methods: For each drink tested (Coca-Cola (TM), Kuat (TM) guarana, Sprite (TM) and light Coca-Cola (TM)), 40 dentine specimens were divided into two subgroups differing with respect to supplementation with green tea extract at 1.2% (OM24 (R), 100% Camellia sinensis leaf extract, containing 30 +/- 3% of catechin; Omnimedica, Switzerland) or not (control). Specimens were subjected to four pH cycles, alternating de-and remineralization in one day. For each cycle, samples were immersed in pure or supplemented drink (10 minutes, 30 mL per block) and in artificial saliva (60 minutes, 30 mL per block) at 37 degrees C, under agitation. Dentine alterations were determined by profilometry (mu m). Data were analysed by two-way ANOVA and Bonferroni`s test (p < 0.05). Results: A significant difference was observed among the drinks tested with Sprite (TM) leading to the highest surface loss and light Coca-Cola (TM) to the lowest. Supplementation with green tea extract reduced the surface loss by 15% to 40% but the difference was significant for Coca-Cola (TM) only. Conclusions: Supplementation of soft drinks with green tea extract might be a viable alternative to reduce their erosive potential against dentine.

Effect of sodium, amine and stannous fluoride at the same concentration and different pH on in vitro erosion

Objective: This study aimed to compare the effects 0.5% and 1% sodium, amine and stannous fluoride at different pH on enamel erosion in vitro. Methods: Bovine enamel samples were submitted to a cyclic de- and remineralisation for 3 days. Each day, the samples were exposed for 120 min to pooled human saliva and subsequently treated with one of the fluoride solutions for 3 min: amine fluoride (AmF, 0.5% and 1% F(-)), sodium fluoride (NaF, 0.5% and 1% F(-)), each at pH 3.9 and 7.0, and stannous fluoride (SnF(2), 0.5% and 1% F-), at pH: 3.9. Additionally, two groups were treated with fluoride-free placebo solutions (pH: 3.9 and 7.0) and one group served as control (no fluoridation). Ten specimens each group were inserted in a so-called artificial mouth and eroded six times daily with hydrochloric acid (pH 2.6) for 90 s each intermitted by exposure to artificial saliva (1 h). After 3 days, enamel loss was analyzed profilometrically and evaluated statistically by ANOVA. Results: Only the acidic 0.5% and 1% SnF(2) and 1% AmF solutions were able to reduce erosive enamel loss significantly, while all other solutions and placebos did not differ significantly from the control. Between the acidic SnF(2) and the 1% AmF solutions no significant differences could be detected. Conclusion: At the same concentrations, acidic SnF(2) and AmF may be more effective than NaF to protect enamel against erosion. (C) 2009 Elsevier Ltd. All rights reserved.

Effect of different concentrations of fluoride in dentifrices on dentin erosion subjected or not to abrasion in situ/ex vivo

This in situ/ex vivo study assessed the effect of different concentrations of fluoride in dentifrices on dentin subjected to erosion or to erosion plus abrasion. Ten volunteers took part in this crossover and double-blind study performed in 3 phases (7 days). They wore acrylic palatal appliances containing 4 bovine dentin blocks divided in two rows: erosion and erosion plus abrasion. The blocks were subjected to erosion by immersion ex vivo in a cola drink (60 s, pH 2.6) 4 times daily. During this step, the volunteers brushed their teeth with one of three dentifrices D (5,000 ppm F, NaF, silica); C (1,100 ppm F, NaF, silica) and placebo (22 ppm F, silica). Then, the respective dentifrice slurry (1: 3) was dripped on dentin surfaces. While no further treatment was performed in one row, the other row was brushed using an electric toothbrush for 30 s ex vivo. The appliances were replaced in the mouth and the volunteers rinsed with water. Dentin loss was determined by profilometry and analyzed by 2-way ANOVA/Bonferroni test (alpha = 0.05). Dentin loss after erosive-abrasive wear was significantly greater than after erosion alone. Wear was significantly higher for the placebo than for the D and C dentifrices, which were not significantly different from each other. It can be concluded that the presence of fluoride concentrations around 1,100 ppm in dentifrices is important to reduce dentin wear by erosion and erosion + abrasion, but the protective effect does not increase with fluoride concentration. Copyright (C) 2008 S. Karger AG, Basel.

The effect of an experimental 4% TiF(4) varnish compared to NaF varnishes and 4% TiF(4) solution on dental erosion in vitro

This in vitro study assessed the effect of an experimental 4% TiF(4) varnish compared to commercial NaF and NaF/CaF(2) varnishes and 4% TiF(4) solution on enamel erosion. For this, 72 bovine enamel specimens were randomly allocated to the following treatments: NaF varnish (2.26% F), NaF/CaF(2) varnish (5.63% F), 4% TiF(4) varnish (2.45% F), F-free placebo varnish, 4% TiF(4) solution (2.45% F) and control (not treated). The varnishes were applied in a thin layer and removed after 6 h. The solution was applied to the enamel surface for 1 min. Then, the specimens were alternately de- and remineralized (6 times/day) in an artificial mouth for 5 days at 37 degrees C. Demineralization was performed with the beverage Sprite (1 min, 3 ml/min) and remineralization with artificial saliva (day: 59 min, 0.5 ml/min; during the night: 0.1 ml/min). The mean daily increment of erosion and the cumulative erosion data were tested using ANOVA and ANCOVA, respectively, followed by Tukey`s test (alpha = 0.05). The mean daily erosion increments and cumulative erosion (micrometers) were significantly less for the TiF(4) varnish (0.30 +/- 0.11/0.65 +/- 0.75) than for the NaF varnish (0.58 +/- 0.11/1.47 +/- 1.07) or the NaF/CaF(2) varnish (0.62 +/- 0.10/1.68 +/- 1.17), which in turn showed significantly less erosion than the placebo varnish (0.78 +/- 0.12/2.05 +/- 1.43), TiF(4) solution (0.86 +/- 0.11/2.05 +/- 1.49) and control (0.77 +/- 0.16/2.06 +/- 1.49). In conclusion, the TiF(4) varnish seems to be a promising treatment to reduce enamel loss under mild erosive conditions. Copyright (C) 2008 S. Karger AG, Basel.

Effect of Smoking on Early Bone Healing Around Oxidized Surfaces: A Prospective, Controlled Study in Human Jaws

Background: This prospective and controlled histologic study evaluates the impact of smoking on bone-to-implant contact, the bone density in the threaded area, and the bone density outside the threaded area around microimplants with anodized surface retrieved from human jaws. Methods: A total of 24 subjects (mean age 51.32 +/- 7.5 years) were divided in two groups: smokers (n = 13 subjects) and non-smokers (n = 11 subjects). Each subject received one microimplant with oxidized surface during conventional mandible or maxilla implant surgery. After 8 weeks, the microimplants and the surrounding tissue were removed and prepared for histomorphometric analysis. Results: Three microimplants placed in smokers showed no osseointegration. The newly formed bone showed early stages of maturation, mainly in the non-smokers. Marginal bone loss, gap, and fibrous tissue were present around implants retrieved from smokers. Histometric evaluation indicated that the mean bone-to-implant contact ranged between 25.97% +/- 9.02% and 40.01% +/- 12.98% for smokers and non-smokers, respectively (P <0.001). Smokers presented 28.17% +/- 10.32% of bone density in the threaded area, whereas non-smokers showed 46.34% +/- 19.12%. The mean of bone density outside the threaded area ranged between 18.76% and 25.11% for smokers and non-smokers, respectively (P>0.05). Conclusion: The present data obtained in human subjects confirm that smoking has a detrimental effect on early bone tissue response around oxidized implant surfaces. J Periodontol 2010;81:575-583.

Preventive effect of an iron varnish on bovine enamel erosion in vitro

Objective: The aim of this study was to evaluate, in vitro, the effect of an experimental varnish containing iron on the dissolution of bovine enamel by carbonated beverage. Methods: Eighty specimens were randomly allocated to four groups (n = 20 per group), according to the following treatments: Fe varnish (FeV, 10 mmoL/L Fe), F varnish (FV, 2.71% F), placebo varnish (PV) and control (not treated, NT). The varnishes were applied in a thin layer and removed after 6 h. Then, the samples were submitted to six cycles, alternating re- and demineralisation (only 1 day). Demineralisation was performed with the beverage Coca-Cola (R) (10 min, 30 mL/block) and remineralisation with artificial saliva for I h. In order to determine the amount of enamel dissolved, the wear was analysed by profilometry. Data were analysed by ANOVA and Tukey`s test (p < 0.05). Results: The mean wear (+/- S.E.) was significantly lesser for the FeV (0.451 +/- 0.018 mu m) when compared to the other treatments. The FV caused significantly less wear (0.554 +/- 0.022 mu m) when compared to PV (0.991 +/- 0.039 mu m) and NT (1.014 +/- 0.033), which did not significantly differ from each other. Conclusions: The results suggest that the iron varnish can interfere with the dissolution of dental enamel in the presence of acidic beverages. (C) 2008 Elsevier Ltd. All rights reserved.

Enamel matrix derivative induces matrix synthesis by cultured human periodontal fibroblast cells

Background: Periodontal wound healing and regeneration require that new matrix be synthesized, creating an environment into which cells can migrate. One agent which has been described as promoting periodontal regeneration is an enamel matrix protein derivative (EMD). Since no specific growth factors have been identified in EMD preparations, it is postulated that EMD acts as a matrix enhancement factor. This study was designed to investigate the effect of EMD in vitro on matrix synthesis by cultured periodontal fibroblasts. Methods: The matrix response of the cells was evaluated by determination of the total proteoglycan synthesis, glycosaminoglycan profile, and hyaluronan synthesis by the uptake of radiolabeled precursors. The response of the individual proteoglycans, versican, decorin, and biglycan were examined at the mRNA level by Northern blot analysis. Hyaluronan synthesis was probed by identifying the isotypes of hyaluronan synthase (HAS) expressed in periodontal fibroblasts as HAS-2 and HAS-3 and the effect of EMD on the levels of mRNA for each enzyme was monitored by reverse transcription polymerase chain reaction (RTPCR). Comparisons were made between gingival fibroblast (GF) cells and periodontal ligament (PDLF) cells. Results: EMD was found to significantly affect the synthesis of the mRNAs for the matrix proteoglycans versican, biglycan, and decorin, producing a response similar to, but potentially greater than, mitogenic cytokines. EMD also stimulated hyaluronan synthesis in both GF and PDLF cells. Although mRNA for HAS-2 was elevated in GF after exposure to EMD, the PDLF did not show a similar response. Therefore, the point at which the stimulation of hyaluronan becomes effective may not be at the level of stimulation of the mRNA for hyaluronan synthase, but, rather, at a later point in the pathway of regulation of hyaluronan synthesis. In all cases, GF cells appeared to be more responsive to EMD than PDLF cells in vitro. Conclusions: EMD has the potential to significantly modulate matrix synthesis in a manner consistent with early regenerative events.

Effect of oxalate desensitizers and dentin moisture during total-etch bonding

Purpose: To evaluate the effect of oxalate during total-etch bonding, under different dentin moisture conditions, over time. The null hypothesis tested was that microtensile bond strength (mu TBS) was not affected by oxalate treatment and dentin moisture during two evaluation periods. Methods: Extracted human third molars had their mid-coronal dentin exposed flat and polished with 600-grit SiC paper. The surfaces were etched with 35% phosphoric acid for 15 seconds, washed and blot dried. After etching, a 3% potassium oxalate gel was applied for 120 seconds, except for the control group (no desensitizer). The surface was then washed and left moist (Wet bonding) or air-dried for 30 seconds (Dry bonding). The surfaces were bonded with: (I) two 2-step etch-and-rinse adhesives: Single Bond (SB); Prime & Bond NT (PBNT) and (2) one 3-step etch-and-rinse adhesive: Scotchbond Multi Purpose (SBMP). Composite buildups were constructed incrementally with Tetric Ceram resin composite. Each increment was cured for 40 seconds. After storage in water for 24 hours or 1 year at 37 C, the specimens were prepared for mu TBS testing with a cross-sectional area of approximately 1 mm(2). They were then tested in tension in an Instron machine at 0.5 mm/minute. Data were analyzed by ANOVA and Student-Newman-Keuls at alpha = 0.05. Results: Application of potassium oxalate had no significant effect on the bond strengths of SBMP and PBNT, regardless of the surface moisture condition (P > 0.05). Conversely, reduced bond strengths were observed after oxalate treatment for SB in both moisture conditions, that being significantly lower when using a dry-bonding procedure (P < 0.05). Lower bond strength was obtained for PBNT when a dry-bonding technique was used, regardless of the oxalate treatment (P < 0.05). After aging the specimens for 1 year, bond strengths decreased. Smaller reductions were observed for SBMP, regardless of moisture conditions. For the WB technique, smaller reductions after 1 year were observed without oxalate treatment for SB and after oxalate treatment for PBNT. (Am J Dent 2010;23:137-141).

Effect of a single application of TiF(4) and NaF varnishes and solutions on dentin erosion in vitro

Objectives: This in vitro study aimed to analyse the effect of a single application of TiF(4) and NaF varnishes and solutions to protect against dentin erosion. Methods: Bovine root dentin samples were pre-treated with NaF-Duraphat varnish (2.26%F, pH 4.5), NaF/CaF(2)-Duofluorid varnish (5.63%F, pH 8.0), NaF-experimental varnish (2.45%F, pH 4.5), TiF(4)-experimental varnish (2.45%F, pH 1.2), NaF solution (2.26%F, pH 4.5), TiF(4) solution (2.45%F, pH 1.2) and placebo varnish (pH 5.0, no-F varnish control). Controls remained untreated. Ten samples in each group were then subjected to an erosive demineralisation (Sprite Zero, 4x 90 s/day) and remineralisation (artificial saliva, between the erosive cycles) cycling for S days. Dentin loss was measured profilometrically after pretreatment and after 1, 3 and 5 days of de-remineralisation cycling. The data were statistically analysed by two-way ANOVA and Bonferroni`s post hoc test (p < 0.05). Results: After pre-treatment, TiF(4) solution significantly induced surface loss (1.08 +/- 0.53 mu m). Only Duraphat reduced the dentin loss overtime, but it did not significantly differ from placebo varnish (at 3rd and 5th days) and TiF(4) varnish (at 3rd day). Conclusions: Duraphat varnish seems to be the best option to partially reduce dentin erosion. However, the maintenance of the effects of this treatment after successive erosive challenges is limited. (C) 2009 Elsevier Ltd. All rights reserved.

Effect of 2% Chlorhexidine Digluconate on the Bond Strength to Normal Versus Caries-affected Dentin

This study evaluated the effect of 2% chlorhexidine digluconate (CHX) used as a therapeutic primer on the long-term bond strengths of two etch-and-rinse adhesives to normal (ND) and caries-affected (CAD) dentin. Forty extracted human molars with coronal carious lesions, surrounded by normal dentin, were selected for this study. The flat surfaces of two types of dentin (ND and CAD) were prepared with a water-cooled high-speed diamond disc, then acidetched, rinsed and air-dried. In the control groups, the dentin was re-hydrated with distilled water, blot-dried and bonded with a three-step (Scotchbond Multi-Purpose-MP) or two-step (Single Bond 2-SB) etch-and-rinse adhesive. In the experimental groups, the dentin was rehydrated with 2% CHX (60 seconds), blot-dried and bonded with the same adhesives. Resin composite build-ups were made. The specimens were prepared for microtensile bond testing in accordance with the non-trimming technique, then tested either immediately or after six-months storage in artificial saliva. The data were analyzed by ANOVA/Bonferroni tests (alpha=0.05). CHX did not affect the immediate bond strength to ND or CAD (p>0.05). CHX treatment significantly lowered the loss of bond strength after six months as seen in the control bonds for ND (p<0.05), but it did not alter the bond strength of CAD (p>0.05). The application of NIP on CHX-treated ND or CAD produced bonds that did not change over six months of storage.

Protective effect of different tetrafluorides on erosion of pellicle-free and pellicle-covered enamel and dentine

The aim was to analyze the protective effects of titanium, zirconium and hafnium tetrafluorides on erosion of pellicle-free and pellicle-covered enamel and dentine in vitro. Eight groups of 20 specimens each of bovine enamel and bovine dentine were prepared. Half the specimens in each group were immersed in human saliva for 2 h for pellicle formation. Specimens were then left untreated (controls) or were treated for 120 s with TiF(4), ZrF(4) or HfF(4) solutions (0.4 or 1%) or 1.25% AmF/NaF gel. All specimens were eroded by exposure to hydrochloric acid, pH 2.6, for 25 min. Cumulative calcium release into the acid was monitored in consecutive 30-second intervals for 5 min, then at 2-min intervals up to a total erosion time of 25 min using the Arsenazo III procedure. Data were analyzed by ANOVA. 1% TiF(4) solution offered the best protective effect, especially in dentine (reduction of calcium loss about 50% at 25 min). 1% ZrF 4, 1% HfF 4 and 0.4% TiF(4) also reduced calcium loss, but to a lesser extent. Long-term effects were limited to dentine, while reduction of enamel erosion (about 25%) was restricted to 1-min erosion. The fluoride gel had a protective effect only in dentine. The efficacy of the tetrafluorides was influenced by the presence of the pellicle layer, in that the protection against dentine erosion by TiF(4) and ZrF(4) was greater on pellicle-covered specimens. Tetrafluoride solutions, especially 1% TiF(4), could decrease dental erosion, but were more effective on dentine than on enamel. Copyright (C) 2008 S. Karger AG, Basel.