Systemic MMP inhibition for periodontal wound repair: results of a multi-centre randomized-controlled clinical trial

Aim: This multi-centre, prospective, controlled trial was designed to examine the biological response of the matrix metalloproteinase(MMP) inhibitor subantimicrobial dose doxycycline (SDD) combined with access flap surgery on periodontal wound repair in patients with chronic severe periodontitis.
Material and Methods: Seventy subjects were enrolled into a 12-month, randomized, placebo-controlled, double-masked trial to evaluate disease response to 6 months therapy and "wash-out" of either placebo+surgery or SDD (20 mg b.i.d.)+surgery. Primary outcome measure included clinical attachment levels (CAL) and secondary outcomes included probing depth (PD), bleeding on probing (BOP), as well as gingival crevicular fluid bone marker assessment [collagen telopeptides (ICTP)]. These measurements were taken at baseline through 12 months post-surgery and drug administration.
Results: Patients treated with SDD and surgery demonstrated stronger reductions in PD in surgically-treated sites of 7 mm as well as gains in CAL ( p <0.004). Furthermore, SDD+surgery resulted in short-term reductions in ICTP levels compared with placebo. Rebounds in ICTP levels and clinical parameters occurred when SDD was withdrawn.
Conclusions: The results from this multi-centre study suggests that SDD in combination with surgery improves the short-term response of periodontal therapy by reducing PD, increasing CAL gain and inhibiting early stage bone resorption.     

Guiding periodontal pocket recolonization: a proof of concept

The complexity of the periodontal microbiota resembles that of the gastro-intestinal tract, where infectious diseases are treatable via probiotics. In the oropharyngeal region, probiotic or replacement therapies have shown some benefit in the prevention of dental caries, otitis media, and pharyngitis, but their effectiveness in the treatment of periodontitis is unknown. Therefore, this study addressed the hypothesis that the application of selected beneficial bacteria, as an adjunct to scaling and root planing, would inhibit the periodontopathogen recolonization of periodontal pockets. Analysis of the data showed, in a beagle dog model, that when beneficial bacteria were applied in periodontal pockets adjunctively after root planing, subgingival recolonization of periodontopathogens was delayed and reduced, as was the degree of inflammation, at a clinically significant level. The study confirmed the hypothesis and provides a proof of concept for a guided pocket recolonization (GPR) approach in the treatment of periodontitis.     

缺氧对人牙周膜成纤维细胞基质金属蛋白酶和组织金属蛋白酶抑制物mRNA表达的影响

目的 探讨缺氧对人牙周膜成纤维细胞基质金属蛋白酶(matrix metalloproteinase,MMP)和组织金属蛋白酶抑制物(tissue inhibitors of matrix metalloproteinase,TIMP) mRNA表达的影响,以期为牙周组织修复再生机制研究提供依据.方法 组织块法培养人牙周膜成纤维细胞,分为缺氧组和常氧组(对照组).缺氧组细胞分别于1％O2、5％ CO2、94％N2的37℃培养箱中培养12、24和48 h(分别为12、24、48 h缺氧组);常氧组细胞在20％O2、5％ CO2、75％N2的37℃培养箱中培养.采用反转录聚合酶链反应技术检测MMP和TIMP相关基因的表达.缺氧组与常氧组间均数比较采用t检验,多组间比较采用单因素方差分析,两两比较采用LSD检验.结果 12、24、48 h缺氧组MMP-2 mRNA的表达呈明显递增趋势(分别为0.769±0.038、0.793±0.043、0.865±0.047),均显著高于常氧组(0.294±0.117),P＜0.01;12h缺氧组TIMP-1,2 mRNA的表达(分别为1.870±0.645、0.862±0.043)均有一过性升高,均分别显著高于常氧组TIMP-1,2 mRNA的表达(分别为0.816±0.043、0.426±0.097),P＜0.05.12h缺氧组MMP-1/TIMP-1 mRNA的比值(0.392±0.206)显著低于常氧组(0.859 ±0.126),P＜0.05;24、48 h缺氧组MMP-2/TIMP-2 mRNA的比值(分别为1.091±0.207、1.264±0.377)均显著高于常氧组(0.695±0.255),P＜0.05.结论 缺氧可以导致MMP-1、MMP-2、TIMP-1、TIMP-2 mRNA的表达,并使MMP-2 mRNA与TIMP-2 mRNA的比值失衡,这可能是缺氧导致牙周炎患者牙周组织破坏加重的机制之一.     

Perforation repair with mineral trioxide aggregate: a modified matrix concept

AIM: To present a modified matrix concept for repair of root perforations using mineral trioxide aggregate (MTA). SUMMARY: Root perforations may occur during preparation of endodontic access cavities or during post-space preparation. The perforation creates the potential for an inflammatory reaction in the periodontal ligament. A concept for the repair of root perforations is presented using a matrix of resorbable collagen. This matrix reconstructs the outer shape of the root and facilitates the adaptation of MTA. The indications for the use of MTA are discussed. Two clinical cases of 5-year successful root perforation repair using the technique are presented. KEY LEARNING POINTS: Long-term perforations with periodontal inflammation can be successfully treated with MTA. Matrices for MTA placement can be developed with commercially available collagen. Infection control within the root canal and at the perforation site is required for satisfactory perforation repair and healing.     

Patterns of diabetic periodontal wound repair: a study using micro-computed tomography and immunohistochemistry

Background: Diabetes is known to impair wound healing and deteriorate the periodontal condition. There is limited information about the patterns and events associated with periodontal wound repair. In this study, we evaluate the dynamics of periodontal wound repair using micro‐computed tomography (microCT) and immunohistochemistry. Methods: Thirty‐six male rats were used, and diabetes was induced by streptozotocin. The maxillary first molars were extracted, and a tooth‐associated osseous defect was created in the extraction area. Animals were sacrificed after 7, 14, and 21 days. Volumetry and distribution of bone trabeculae were evaluated by microCT imaging. The patterns of healing and collagen alignment were evaluated by histology. Advanced glycation end‐product (AGE) deposition and expression of the receptor for AGEs (RAGE), tartrate‐resistant acid phosphatase, and proliferating cell nuclear antigen were evaluated by histochemical and immunohistochemical staining. Results: Diabetic animals demonstrated a significantly reduced bone volume and trabecular number as well as thinner trabeculae and more trabecular separation in osseous defects. The early stage was characterized by significantly reduced cellular proliferation and prolonged active inflammation without evident bone resorption, whereas delayed recovery of collagen realignment, matrix deposition, and bone turnover was noted in later stages. Although AGEs and RAGE were present during healing in diabetes and controls, a stronger and more persistent level of expression was observed in the group with diabetes Conclusions: Diabetes significantly delayed osseous defect healing by augmenting inflammation, impairing proliferation, and delaying bone resorption. The AGE–RAGE axis can be activated under metabolic disturbance and inflammation.     

釉基质蛋白对牙周细胞覆盖体外创面的影响

目的：评价体外创面模型环境中,釉基质蛋白对牙周膜细胞、牙龈成纤维细胞覆盖创面能力的影响。方法：利用在盖玻片上形成的人牙周膜和牙龈成纤维细胞的融合培养物,以机械方法去除7mm宽的细胞层条带,形成体外创面模型。受损培养物在含有10％胎牛血清的培养液中继续培养2、6、9d,同时以100μg／ml的釉基质蛋白分别刺激牙周膜、牙龈成纤维细胞,并与不加釉基质蛋白者作对照。玻片经同定后作甲紫染色。以计算机辅助图像分析系统对细胞覆盖体外创面的面积进行百分比定量,采用SAS6、12软件包进行样本均数的t检验。结果：对照组组内牙周膜、牙龈成纤维细胞覆盖创面的面积存在差异,牙龈成纤维细胞覆盖创面面积在创面形成后第9天显著高于牙周膜细胞,差异有显著性（P〈0.05）。在加用100μg／ml釉基质蛋白的条件下,牙周膜细胞覆盖体外创面的面积较对照组明显增加．创面形成后第6、9天,牙周膜、牙龈成纤维细胞覆盖体外创面面积均无显著差异（P〉0．05）。结论：牙龈成纤维细胞覆盖创面的能力高于牙周膜细胞。釉基质蛋白有增进创面愈合,特别是牙周膜细胞创面覆盖的作用。     

细胞外基质磷酸糖蛋白在大鼠牙周组织缺损愈合过程中的表达

目的:观察细胞外基质磷酸糖蛋白(matrix extracellular phosphoglycoprotein,MEPE)在大鼠牙周组织缺损愈合过程中的表达,初步探讨MEPE在牙周组织再生中可能发生的作用。方法:24只成年健康雄性Wistar大鼠随机分2组:术后14 d组和术后28 d组各12只,行左侧下颌骨开窗术,制备牙周组织缺损模型,HE染色观察牙周组织缺损愈合情况,免疫组织化学染色法观察MEPE在牙周组织缺损愈合过程中各组织的表达。结果:术后14 d,术区有部分新生牙槽骨形成,部分牙周纤维附着于根面牙本质上;术后28 d,术区完全被新生牙槽骨覆盖,在新生牙槽骨和牙本质之间可见牙周膜和部分牙骨质生成,牙周膜大部分附着于根面上;牙周组织缺损愈合过程中,MEPE在健康对照侧仅呈弱阳性表达,而在缺损区牙槽骨和牙周膜相关细胞中均呈阳性表达。结论:在牙周组织缺损愈合过程中,细胞外基质磷酸糖蛋白参与牙槽骨以及牙周膜的再生。     

Influence of phase I periodontal therapy on levels of matrix metalloproteinase 1 and tissue inhibitor of metalloproteinase 1

Background

Matrix metalloproteinase-1 (MMP-1) is a member of a family of enzymes that can degrade most extracellular matrix macromolecules. Extracellularly, MMPs are controlled by tissue inhibitors of metalloproteinases (TIMPs) and by mechanisms of pro-MMP activation. Levels of MMPs and TIMPs change during healing, inflammation, and normal tissue turnover. Herein we aimed to evaluate the levels of MMP-1 and TIMP-1 in gingival crevicular fluid (GCF) from periodontally healthy patients (control group) and chronic periodontitis patients before and after phase 1 therapy.

Methods

In this study we examined 30 patients who had chronic periodontitis with probing depth sites ⩾5 mm and a clinical attachment level (CAL) ⩾5 mm. We included 30 periodontally healthy patients as a control. Clinical measurements such as plaque (PI) and gingival (GI) indices, papillary bleeding index (PBI), probing depths (PD), and CAL were recorded both before treatment (BT) and after phase I periodontal treatment (AT). Assays for MMP-1 and TIMP-1 were performed with an enzyme-linked immunosorbent assay (ELISA) method.

Results

All clinical parameters were significantly reduced at the post-therapy visit. MMP-1 levels were significantly higher in patients BT than the controls; however, the patients AT were not statistically different than the controls. TIMP-1 levels in patients BT were significantly lower than in the controls and significantly lower than patients AT. We observed a significant positive correlation between GCF volume and MMP-1 levels. Furthermore, TIMP-1 levels were significantly negatively correlated with both GCF volume and all clinical parameters.

Conclusions

We observed that as the extent of periodontal destruction increases, MMP-1 concentration increases and TIMP-1 concentration decreases in GCF. When chronic periodontitis patients were treated by scaling and root planing (SRP), the average MMP-1 concentrations decreased and TIMP-1 concentrations increased in GCF.     

Use of a fluorogenic septapeptide matrix metalloproteinase assay to assess responses to periodontal treatment

BACKGROUND: Quantification of gingival crevicular fluid matrix metalloproteinase activity may provide improved assessment of periodontal disease status and response to treatment. A fluorogenic matrix metalloproteinase substrate assay (FSA) has been developed using a methoxycoumarin-containing septapeptide analog of the alpha2(I) collagen cleavage site. This substrate exhibits increased fluorescence following cleavage by many matrix metalloproteinases, and the enzyme activity can be readily estimated with a fluorimeter. Here we compared this assay with classical methods of periodontal assessment including bleeding on probing, crevicular fluid flow, and probing depth to assess its utility as an indicator of changes in periodontal status and treatment response. METHODS: Complete measurements of probing depth were obtained for Ramfjord teeth on subjects who had been previously treated for periodontitis. Subjects were subsequently divided into groups based on existing periodontal disease severity: gingivitis (n = 21), stable periodontitis (n = 41), and severe periodontitis (n = 50). Crevicular fluid volume, bleeding on probing, and FSA were measured at each Ramfjord tooth or substitute. After baseline measurements, subjects received subgingival scaling and prophylaxis; 3 months later, they were reassessed. RESULTS: FSA measurements were positively associated with severity of disease at baseline. After treatment there were substantial reductions of FSA in gingivitis (approximately 51%; P <0.01) and severe periodontitis (approximately 45%; P <0.001), but not in stable periodontitis (13%; P >0.2). All groups showed a positive association between FSA measurements and higher bleeding scores at individual sites. FSA measurements were also positively associated with crevicular fluid flow at baseline, but after treatment there was a approximately 67% decrease (P <0.01) in the highest crevicular fluid flow class. There were significant reductions of FSA at follow-up for sites with probing depths between 0 to 3 mm (23%; P <0.05) and 4 to 6 mm (31%; P <0.05). However, the largest reduction was for sites with probing depth between 7 to 9 mm (49%; P <0.001). CONCLUSIONS: These results indicate that monitoring patients by measurement of matrix metalloproteinase levels in gingival crevicular fluid with the quenched fluorescent substrate assay provides estimates of inflammatory status, periodontal destruction, and response to treatment, especially in more severe periodontitis lesions.     

Inhibition of alveolar bone loss by matrix metalloproteinase inhibitors in experimental periodontal disease

Periodontal disease is characterized by excessive host collagenase resulting in loss of gingival and periodontal ligament collagen and adjacent alveolar bone. Intragingival endotoxin injection induces a model of periodontal disease characterized by rapid bone loss with biochemical features similar to that of naturally occurring adult periodontitis. CH1766, a peptide with a zinc binding moeity which fits into the active site of the enzyme, and CH6631, a hydroxamic acid derivative with aryl-substituted sulphonamide residues, are inhibitors of matrix metalloproteinases (MMPIs) with differing inhibitory profiles as characterized by in vitro assays. In this study, endotoxin was injected into the gingivae of rats which were then treated orally with either 3 mg/kg or 30 mg/kg of one of the two inhibitory compounds. The gingival tissues were assessed for collagenase and gelatinase activity, plus three different pro-inflammatory cytokines. In addition, alveolar bone height in defleshed jaws was studied by computerized morphometric analysis and scanning electron microscopy. Both drugs reduced active and/or total MMP activity, in many cases to normal, and also partially normalized cytokine levels as well. A dose-response effect was seen with regard to amelioration of lipopolysaccharide-induced alveolar bone loss with both drugs. Other than studies with tetracyclines, this is the first report of beneficial effects of MMPIs in a model of periodontal disease, strongly suggesting that this class of agents could bring therapeutic benefit to patients with this disorder, and that periodontal disease can be used as a model to demonstrate in vivo efficacy of this class of drugs.     

Effect of alendronate on periodontal disease in postmenopausal women: a randomized placebo-controlled trial

BACKGROUND: We investigated the effect of oral alendronate (ALN) treatment on radiological and clinical measurements of periodontal disease in postmenopausal women without hormone replacement therapy. METHODS: We evaluated the effect of 6 months of ALN treatment in 40 postmenopausal women, 55 to 65 years old with established periodontal disease, in a controlled, double-masked, prospective study. Volunteers were paired by age and randomized to receive ALN (10 mg/day) or placebo for the study period. Periodontal mechanical treatment was carried out in both groups. At baseline and after treatment, clinical evaluation, hormone blood levels, distance from the crestal alveolar bone (CAB) to the cemento-enamel junction (CEJ), calcaneus bone mineral density (BMD), hormone levels, serum N-telopeptide (NTx), and bone-specific alkaline phosphatase (BSAP) were assessed. RESULTS: Periodontal disease conditions improved in both groups, but greater improvement in probing depth (-0.8 +/- 0.3 mm versus -0.4 +/- 0.4 mm, P = 0.02) and gingival bleeding (-0.3% +/- 0.13% versus -0.2% +/- 0.06%, P = 0.006) was found in the ALN treated group. Calcaneus BMD increased in the ALN treated group (68 +/- 47 mm3 versus -26 +/- 81 mm3, P = 0.0006). CAB-CEJ distance diminished in the ALN group (-0.4 +/- 0.40 mm versus 0.60 +/- 0.53 mm, P = 0.00008). Marginal reduction in both NTx and BSAP levels was found in the ALN group (-9.4 +/- 6.6 nmol versus -4.3 +/- 4.7 nmol bone collagen equivalents, P = 0.08, and -7.7 +/- 8.4 versus -1.5 +/- 5.0 U/l, P = 0.1, respectively). Hormone levels were unchanged after treatment. Similar improvement of calcaneus BMD and CAB-CEJ distance with ALN treatment was found in obese and non-obese women. CONCLUSION: ALN treatment improved periodontal disease and bone turnover in postmenopausal women.     

Effect of rhPDGF-BB on bone turnover during periodontal repair

PURPOSE: Growth factors such as platelet-derived growth factor (PDGF) exert potent effects on wound healing including the regeneration of periodontia. Pyridinoline cross-linked carboxyterminal telopeptide of type I collagen (ICTP) is a well-known biomarker of bone turnover, and as such is a potential indicator of osseous metabolic activity. The objective of this study was to evaluate the release of the ICTP into the periodontal wound fluid (WF) following periodontal reconstructive surgery using local delivery of highly purified recombinant human PDGF (rhPDGF)-BB. METHODS: Forty-seven human subjects at five treatment centres possessing chronic severe periodontal disease were monitored longitudinally for 24 weeks following PDGF regenerative surgical treatment. Severe periodontal osseous defects were divided into one of three groups and treated at the time of surgery with either: beta-tricalcium phosphate (TCP) osteoconductive scaffold alone (active control), beta-TCP+0.3 mg/ml of rhPDGF-BB, or beta-TCP+1.0 mg/ml of rhPDGF-BB. WF was harvested and analysed for local ICTP levels by radioimmunoassay. Statistical analysis was performed using analysis of variance and an area under the curve analysis (AUC). RESULTS: The 0.3 and 1.0 mg/ml PDGF-BB treatment groups demonstrated increases in the amount of ICTP released locally for up to 6 weeks. There were statistically significant differences at the week 6 time point between beta-TCP carrier alone group versus 0.3 mg/ml PDGF-BB group (p<0.05) and between beta-TCP alone versus the 1.0 mg/ml PDGF-BB-treated lesions (p<0.03). The AUC analysis revealed no statistical differences amongst groups. CONCLUSION: This study corroborates the release of ICTP as a measure of active bone turnover following local delivery of PDGF-BB to periodontal osseous defects. The amount of ICTP released from the WF revealed an early increase for all treatment groups. Data from this study suggests that when PDGF-BB is delivered to promote periodontal tissue engineering of tooth-supporting osseous defects, there is a direct effect on ICTP released from the wound.     

硝苯地平和机械力对人牙周膜成纤维细胞基质金属蛋白酶的表达影响

目的研究机械静态拉伸作用下,硝苯地平对人牙周膜成纤维细胞（HPDLF）基质金属蛋白酶（MMP）-10和MMP-13的表达影响。方法按弹力形变不同将细胞随机分为4组,分别为0%、8%、12%、16%形变组,每组再按照硝苯地平浓度不同分为4个亚组,分别为0、10、30、50 μm亚组。硝苯地平孵育1 h后,给予细胞12 h静态拉伸,免疫组化染色检测细胞胞浆中MMP-10和MMP-13的表达。结果弹性形变为0%时,各亚组中MMP-10和MMP-13的表达无明显变化,与对照组相比差异无统计学意义（P>0.05）。当硝苯地平浓度为0 μm时,8%、12%、16%形变组胞浆内MMP-10和MMP-13均呈高表达,且随形变的增大,表达呈上升趋势（P<0.001）;当加入硝苯地平后,随硝苯地平浓度的增加,MMP-10和MMP-13表达均呈下降趋势（P<0.001）。结论硝苯地平对机械力诱导的MMP-10和MMP-13表达有抑制作用,提示钙离子通道参与机械力对HPDLF中MMP-10和MMP-13的诱导表达。     

Effects of periodontal therapy on systemic markers of inflammation in patients with metabolic syndrome: a controlled clinical trial

Background: The systemic inflammation in both metabolic syndrome (MetS) and periodontitis is a common denominator of the association of these conditions with higher risk of atherosclerosis. The current study investigates whether periodontal therapy may reduce systemic inflammation in patients with MetS and reduce cardiovascular risk. Methods: A parallel‐arm, double‐blind, randomized clinical trial of 1‐year duration in patients with MetS and periodontitis was conducted. Participants were randomized to an experimental treatment group (ETG) (n = 82) that received plaque control and root planing plus amoxicillin and metronidazole or to a control treatment group (CTG) (n = 83) that received plaque control instructions, supragingival scaling, and two placebos. Risk factors for cardiovascular disease were recorded; serum lipoprotein cholesterol, glucose, body mass index (BMI), C‐reactive protein (CRP) and fibrinogen concentrations, and clinical periodontal parameters were assessed at baseline and every 3 months until 12 months after therapy. The primary and secondary outcomes were changes in CRP and fibrinogen levels, respectively. Results: The baseline patients’ characteristics of both groups were similar. No significant changes in lifestyle factors, frequency of hypertension, BMI, serum lipoprotein cholesterol, and glucose levels were observed during the study period. The periodontal parameters significantly improved in both groups 3 months after therapy (P = 0.0001) and remained lower than baseline up to 12 months. The improvement of periodontal status was significantly greater in the ETG (P = 0.0001). A multiple linear regression analysis, controlled for sex, smoking, hypertension, and extent of periodontitis, demonstrated that CRP levels decreased with time and that this reduction was significant at 9 (P = 0.024) and 12 (P = 0.001) months in both groups, without difference between the groups. Fibrinogen levels significantly decreased in the ETG at 6 and 12 months but not in the CTG. Conclusion: Reduction of periodontal inflammation either with root planing and systemic antibiotics or with plaque control and subgingival scaling significantly reduces CRP levels after 9 months in patients with MetS.     

Effect of eucalyptus extract chewing gum on periodontal health: a double-masked, randomized trial

BACKGROUND: Studies in vitro showed that eucalyptus extracts possess antibacterial activity against cariogenic and periodontopathic bacteria; however, the clinical effects with respect to periodontal health in humans remain unproven. The objective of this study was to evaluate the effect of chewing gum containing eucalyptus extract on periodontal health in a double-masked, randomized, controlled trial. METHODS: Healthy humans with gingivitis but not deep periodontal pockets were randomly assigned to the following groups: high-concentration group (n=32): use of 0.6% eucalyptus extract chewing gum for 12 weeks (90 mg/day); low-concentration group (n=32): use of 0.4% eucalyptus extract chewing gum for 12 weeks (60 mg/day); and placebo group (n=33): use of chewing gum without eucalyptus extract for 12 weeks. Plaque accumulation (PLA), gingival index (GI), bleeding on probing (BOP), periodontal probing depth (PD), and clinical attachment level (CAL) were measured at weeks 0, 4, 8, 12, and 14. Significance was analyzed with repeated-measures two-way analysis of variance followed by the Games-Howell pairwise comparison test. RESULTS: The interaction between the effects of eucalyptus extract chewing gum and the intake period was statistically significant for PLA, GI, BOP, and PD but not for CAL. The low- and high-concentration groups exhibited statistically significant (P <0.05) improvements compared to the placebo group for PLA, GI, BOP, and PD. CONCLUSIONS: Eucalyptus extract chewing gum had a significant effect on PLA, GI, BOP, and PD. The use of eucalyptus extract chewing gum may promote periodontal health.     

The inhibition effect of non-protein thiols on dentinal matrix metalloproteinase activity and HEMA cytotoxicity

Objectives

Phosphoric acid (PA) etching used in etch-and-rinse adhesives is known to activate host-derived dentinal matrix-metalloproteinases (MMPs) and increase dentinal permeability. These two phenomena will result, respectively; in degradation of dentine-adhesive bond and leaching of some monomers especially 2-hydroxyethyl methacrylate (HEMA) into the pulp that would negatively affect the viability of pulpal cells. This study is the first to investigate the inhibitory effect of non-protein thiols (NPSH); namely reduced glutathione (GSH) and N-acetylcysteine (NAC) on dentinal MMPs and compare their effects on HEMA cytotoxicity.

Methods

Dentine powder was prepared from human teeth, demineralized with 1% PA and then treated with 2% GSH, 2% NAC or 2% chlorhexidine (CHX). Zymographic analysis of extracted proteins was performed. To evaluate the effect of GSH, NAC and CHX on HEMA cytotoxicity, solutions of these compounds were prepared with or without HEMA and rat pulpal cells were treated with the tested solutions for (6 and 24 h). Cells viability was measured by means of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cytotoxicity data were analysed by one-way ANOVA and Tukey post hoc tests (p < 0.05).

Results

The inhibitory effect of GSH and NAC on dentinal MMPs was confirmed. GSH showed similar effectiveness to NAC regarding HEMA cytotoxicity inhibition.

Conclusion

NPSH were effective to inhibit dentinal MMPs and HEMA cytotoxicity.

Clinical significance

The tested properties of NPSH provide promising clinical use of these agents which would enhance dentine-bond durability and decrease post-operative sensitivity.