A possible mechanism of low molecular weight protein tyrosine phosphatase (LMW-PTP) activity modulation by glutathione action during human osteoblast differentiation

Objective

Low molecular weight protein tyrosine phosphatases (LMW-PTPs) are a family of enzymes strongly involved in the regulation of cell growth and differentiation. Since there is no information concerning the relationship between osteoblastic differentiation and LMW-PTP expression/activity, we investigated its involvement during human osteoblast-like cells (hFOB 1.19) differentiation. It is known that LMW-PTP is regulated by an elegant redox mechanism, so we also observed how the osteoblastic differentiation affected the reduced glutathione levels.

Design

hFOB 1.19 cells were cultured in DMEM/F12 up to 35 days. The osteoblast phenotype acquisition was monitored by measuring alkaline phosphatase activity and mineralized nodule formation by Von Kossa staining. LMW-PTP activity and expression were measured using the p-nitrophenylphosphate as substrate and Western blotting respectively. Crystal violet assay determined the cell number in each experimental point. Glutathione level was determined by both HPLC and DNTB assays.

Results

LMW-PTP modulation was coincident with the osteoblastic differentiation biomarkers, such as alkaline phosphatase activity and presence of nodules of mineralization in vitro. Likewise LMW-PTP, the reduced glutathione-dependent microenvironment was modulated during osteoblastic differentiation. During this process, LMW-PTP expression/activity, as well as alkaline phosphatase and glutathione increased progressively up to the 21st day (p < 0.001) of culturing, decreasing thereafter.

Conclusions

Our results clearly suggest that LMW-PTP expression/activity was rigorously modulated during osteoblastic differentiation, possibly in response to the redox status of the cells, since it seems to depend on suitable levels of reduced glutathione. In this way, we pointed out LMW-PTP as an important signaling molecule in osteoblast biology and bone formation.     

Evaluation of the antimicrobial effectiveness of citric acid and sodium hypochlorite on the anaerobic flora of the infected root canal

This study was designed to evaluate the antimicrobial effectiveness of 25% citric acid, compared with 2.5% sodium hypochlorite, after time intervals of 5, 15, 30 and 60 min. Anaerobic bacterial species were isolated from infected root canals and categorized according to Gram stain as Gram-positive cocci, Gram-negative cocci, Gram-positive rods and Gram-negative rods. The experimental method used was similar to that proposed by the German society for Hygiene and Microbiology (DGHM) with slight modifications. Testing revealed that citric acid does demonstrate anti microbial properties against anaerobic bacteria, especially against cocci, but it is less effective than 2.5% sodium hypochlorite.     

Effect of 5% sodium hypochlorite or Tubulicid pretreatment in vivo on the marginal adaptation of dental adhesives and glass ionomer cements

The effect of pretreatment of dentin with a 5% sodium hypochlorite solution (NaOCl) or Tubulicid on the marginal adaptation of a glass ionomer cement (FUJI), a glass ionomer cement reinforced with silver particles (Ketac Silver) and 3 dentin adhesives (Clearfil, Dentin Bonding Agent and Scotch Bond) was tested in vivo. After a one month experimental period, the formation of gaps was measured from SEM photomicrographs. The sodium hypochlorite pretreated glass ionomer cement fillings showed gapfree margins, while the Tubulicid pretreated ones showed locally small gaps. When the 3 resinous dentin adhesives were used gaps were observed over the whole length of the dentinal margin with both techniques of pretreatment.     

Evaluation of the surface free energy on root canal dentine walls treated with chelating agents and NaOCl

AIM: To evaluate ex vivo the effects of combined and single use of EDTA, RC-Prep and NaOCl on the surface free energy of canal wall dentine using the captive bubble technique. METHODOLOGY: Eighteen extracted human pre-molar teeth were sectioned at the crown and the apical third, the remaining mid-root portion were bisected longitudinally. Thereafter, the root halves were embedded in resin blocks that exposed the dentine surface of the canal wall. The specimens were randomly assigned to six experimental groups (n = 6) after polishing. The root dentine surfaces of the first two groups were treated with 17% EDTA or RC-Prep followed by 2.5% NaOCl irrigation. Groups 3, 4 and 5 were treated with either 17% EDTA, RC-Prep or 2.5% NaOCl alone. Control specimens were irrigated with saline solution. The surface free energies of experimental groups were calculated by measuring air and octane contact angles on the canal wall dentine. Statistical analysis was performed using the Mann-Whitney U and Bonferroni post-tests at P = 0.05. RESULTS: Compared with the control group; combined and single use of EDTA, RC-Prep and NaOCl irrigation significantly decreased the surface free energy of canal wall dentine surfaces (P < 0.05). Among all groups tested, the use of NaOCl as a final flush following RC-Prep treatment yielded increased wettability. Nevertheless, this value remained lower than that of the control group. CONCLUSION: Use of chelating agents alone or in combination with NaOCl decreased the wettability of root canal wall dentine.     

Do buffered local anesthetics provide more successful anesthesia than nonbuffered solutions in patients with pulpally involved teeth requiring dental therapy?: A systematic review

Background

The authors conducted a systematic review that addresses the following population, intervention, comparison, outcome question: “In adults requiring dental therapy with pulpally involved teeth, what is the comparative efficacy of buffered local anesthetics (LAs) compared with that of nonbuffered LAs in achieving anesthetic success?”

Ex vivo evaluation of the effectiveness of bleaching agents on the shade alteration of blood-stained teeth

Aim To evaluate ex vivo effectiveness of the three formulations of bleaching materials for intracoronal bleaching of root filled teeth using the walking bleach technique. Methodology Extracted premolar teeth were stained artificially with human blood. After biomechanical preparation, the root canals were filled and a 3‐mm thick intermediate base of zinc phosphate cement was placed at the level of the cementoenamel junction. The teeth were divided into four groups (n = 12): C (control, without bleaching material), A1 (sodium perborate + distilled water), A2 (sodium perborate + 10% carbamide peroxide) and A3 (sodium perborate + 35% carbamide peroxide). The bleaching materials were changed at 7 and 14 days. Evaluation of shade was undertaken with aid of the VITA Easyshade? (ΔE*ab) and was performed after tooth staining and at 7, 14 and 21 days after bleaching, based on the CIELAB system. Data were analysed by anova for repeated measurements, Tukey and Dunnett tests (α = 0.05). Results The Tukey test revealed that group A1 (10.58 ± 4.83 ΔE*ab) was statistically different from the others (A2, 19.57 ± 4.72 ΔE*ab and A3, 17.58 ± 3.33 ΔE*ab), which were not different from each other. At 7 days: A1 was significantly different from A2; at 14 and 21 days: A2 and A3 were significantly better than A1; the Dunnett test revealed that the control group was different from A1, A2 and A3 at all periods (P < 0.05). Conclusion Sodium perborate associated with both 10% and 35% carbamide peroxide was more effective than when associated with distilled water.     

Efficacy of various concentrations of NaOCl and instrumentation techniques in reducing Enterococcus faecalis within root canals and dentinal tubules

AIM: To evaluate the efficacy of 0.5%, 2.5% and 5.25% sodium hypochlorite (NaOCl) as intracanal irrigants associated with hand and rotary instrumentation techniques against Enterococcus faecalis within root canals and dentinal tubules. METHODOLOGY: A total of 180 extracted human premolar teeth were infected for 21 days with E. faecalis. The specimens were divided into 12 groups, as follows: group 1: 5.25% NaOCl + Hybrid technique (Valdrighi et al. 1998); group 2: 5.25% NaOCl + nickel-titanium (NiTi) rotary technique 4 mm shorter than the apex (by FOP-UNICAMP); group 3: 5, 25% NaOCl + NiTi rotary technique (Hero 642); group 4: 2.5% NaOCl +Hybrid technique; group 5: 2.5% NaOCl + NiTi rotary technique 4 mm shorter than the apex; group 6: 2.5% NaOCl + NiTi rotary technique (Hero 642); group 7: 0.5% NaOCl + Hybrid technique; group 8: 0.5% NaOCl + NiTi rotary technique 4 mm shorter than the apex; group 9: 0.5% NaOCl + NiTi rotary technique (Hero 642); group 10: sterile saline solution + Hybrid technique; group 11: sterile saline solution + NiTi rotary technique 4 mm shorter than the apex; group 12: sterile saline solution + NiTi rotary technique (Hero 642). Canals were sampled before and after preparation. After serial dilution, samples were plated onto brain heart infusion (BHI) agar, and the colony forming units (CFU) that were grown were counted. The teeth were sectioned into three thirds and dentine chips were removed from the canals with conical burs. The samples obtained with each bur were immediately collected into test tubes containing BHI broth, and were incubated at 37 degrees C and plated onto BHI agar. The CFU were counted and analysed. RESULTS: At all depths and thirds of the root canals and for all techniques used, 5.25% NaOCl was shown to be the most effective irrigant solution tested when dentinal tubules were analysed, followed by 2.5% NaOCl. No differences among concentrations in cleaning the canals were found. CONCLUSIONS: Especially at higher concentrations, NaOCl, was able to disinfect the dentinal tubules, independent of the canal preparation technique used.     

Effectiveness in cleaning oval-shaped root canals using Anatomic Endodontic Technology, ProFile and manual instrumentation: a scanning electron microscopic study

AIM: To compare in vitro the cleanliness of root canal walls in oval-shaped root canals following automated or manual instrumentation. METHODOLOGY: Forty-five oval-shaped single-rooted maxillary and mandibular premolars with straight canals were divided into three groups of 15. Automated canal preparation was performed using Anatomic Endodontic Technology (AET, group 1) and the ProFile system (group 2). Manual instrumentation (group 3) was performed with K-Flexofiles. Irrigation was performed using alternately 5.25% NaOCl and 17% EDTA, followed by rinsing with saline. The roots were split longitudinally into halves and the canals examined at x200 and x400 in a scanning electron microscope. The presence of debris and smear layer was recorded at distances of 1, 5 and 10 mm from the working length using a three-step scoring scale and a 300 mum square grid. Mean scores for debris and smear layer were calculated and statistically analysed for significance (P < 0.05) between and within groups, using the Kruskal-Wallis nonparametric anova and Dunn's tests. RESULTS: At 1, 5 and 10-mm levels the root canals prepared with AET had significantly less surface debris and smear layer on the canal walls compared with canals prepared with ProFile or manual instrumentation. For all three groups significantly lower mean smear layer scores (P < 0.05) were recorded at 5 and 10-mm levels compared with the 1 mm level. Significantly lower mean debris scores (P < 0.05) were also recorded at 5 and 10-mm levels for the AET group whereas no significant differences were found between the three levels for the ProFile and manual instrumentation groups. CONCLUSIONS: Although better instrumentation scores were obtained in canals prepared with AET, complete cleanliness was not achieved by any of the techniques and instruments investigated.     

Potential agents to control enamel caries-like lesions

Objectives

To assess whether pastes containing casein phosphopeptide–amorphous calcium phosphate (CPP–ACP) and calcium sodium phosphosilicate (CSP) control artificial caries lesion progression.

Methods

Enamel slabs of bovine teeth were embedded in polyester resin and had their enamel surfaces serially polished, and tested for surface microhardness (SMH, 25 g, 5 s). Incipient caries-like lesions were pre-formed and specimens were evaluated by microhardness test (SMH_post-lesion) and randomly assigned to five treatment groups (n = 15): (1) regular dentifrice (RE, 1,100 ppm F); (2) dentifrice with calcium sodium phosphosilicate (CSP); (3) amorphous calcium phosphate stabilized by casein phosphopeptide (CPP–ACP); (4) CPP–ACP with 900 ppm F (CPP–ACP + F) and (5) control group—unexposed to any remineralizing agent. Treatments were applied five times, after the de-remineralization period in the cariogenic challenges. Post-treatments SMH measurements were conducted (SMH_{post-treatment}).

Results

ANOVA was applied for data evaluation and revealed a significant difference among the treatments (p = 0.0161). Tukey's test was conducted and the percentage of mineral loss was calculated. Specimens exposed to CSP (7.1%), RE (6.7%) and CPP–ACP + F (3.8%) showed lower mineral loss than those that in the control group (−11.0%). CPP–ACP group (3.2%) differed from the control, CSP and RE groups.

Conclusions

Depending on the agent used, a remineralizing effect may be expected, which reflects in caries lesions progression.     

双氯芬酸钠含片治疗口腔溃疡性疼痛的临床研究

目的 :评价双氯芬酸钠含片对口腔溃疡引起的疼痛的临床疗效和安全性。方法 :采用多中心、随机、双盲双模拟、阳性药物双氯芬酸钠片平行对照试验。治疗 82例口腔溃疡病例 ,观察VAS、JPQ1、JPQ2、JPQ3的起效时间、维持时间和最大止痛效果。并采用PP和ITT分析方法。结果 :试验组的起效时间、维持时间均短于对照组 (P <0 .0 5 ) ,试验组治疗VAS、JPQ1、JPQ2、JPQ3的最大止痛效果优与对照组 (P <0 .0 5 ) ,试验组的不良反应发生率低于对照组 (P <0 .0 5 )。结论 :双氯芬酸钠含片能快速、有效地缓解和消除口腔溃疡引起的疼痛。