半胱氨酸组织蛋白酶对牙本质粘接耐久性的影响

半胱氨酸组织蛋白酶是组织蛋白酶家族的主要成员.牙本质酸蚀脱矿后裸露的胶原纤维被内源性蛋白酶降解是影响牙本质粘接耐久性的主要因素之一.除基质金属蛋白酶外,半胱氨酸组织蛋白酶也在粘接过程中被激活并参与混合层中胶原的破坏.本文就半胱氨酸组织蛋白酶与基质金属蛋白酶的相互作用、在牙本质粘接中的作用以及半胱氨酸组织蛋白酶抑制剂对提高牙本质粘接耐久性的作用的研究进展作一综述.     

Chlorhexidine rinsing inhibits biofilm formation and causes biofilm disruption on dental enamel in situ

Clinical Oral Investigations - This in situ study aims to evaluate the effects of chlorhexidine (CHX) mouth rinsing on biofilm formation and moreover on the disruption of existing mature dental...     

The inhibitory effects of silver diamine fluorides on cysteine cathepsins

Aim

The expression of cysteine cathepsins in human carious dentine suggests that this enzyme contributes to the collagen degradation in caries progress. This study investigated whether silver diamine fluoride (SDF) inhibited the activity of cysteine cathepsins.

Methods

Three commercial SDF solutions with concentrations at 38%, 30% and 12% were studied. Two fluoride solutions with the same fluoride ion (F^-) concentrations as the 38% and 12% SDF solutions, and 2 silver solutions with the same silver ion (Ag⁺) concentrations as the 38% and 12% SDF solutions were prepared. Five samples of each experimental solution were used to study their inhibitory effect on two cathepsins (B and K) using cathepsin assay kits. Positive control contained assay buffer and cathepsins dilution was used to calculate the percentage inhibition (difference between the mean readings of the test solution and control solution divided by that of the control group).

Results

The percentage inhibition of 38%, 30% and 12% SDF on cathepsin B were 92.0%, 91.5% and 90.3%, respectively (p < 0.001); on cathepsin K were 80.6%, 78.5% and 77.9%, respectively (p < 0.001). Ag⁺ exhibited the inhibitory effect against both cathepsin B and K with or without the presence of F^- (p < 0.01). The solutions containing Ag⁺ have significantly higher inhibitory effect than the solutions containing F^- only (p < 0.01).

Conclusion

According to this study, SDF solution at all 3 tested concentrations significantly inhibited the activity of cathepsin B and K.     

Co-distribution of cysteine cathepsins and matrix metalloproteases in human dentin

It has been hypothesized that cysteine cathepsins (CTs) along with matrix metalloproteases (MMPs) may work in conjunction in the proteolysis of mature dentin matrix. The aim of this study was to verify simultaneously the distribution and presence of cathepsins B (CT-B) and K (CT-K) in partially demineralized dentin; and further to evaluate the activity of CTs and MMPs in the same tissue. The distribution of CT-B and CT-K in sound human dentin was assessed by immunohistochemistry. A double-immunolabeling technique was used to identify, at once, the occurrence of those enzymes in dentin. Activities of CTs and MMPs in dentin extracts were evaluated spectrofluorometrically. In addition, in situ gelatinolytic activity of dentin was assayed by zymography. The results revealed the distribution of CT-B and CT-K along the dentin organic matrix and also indicated co-occurrence of MMPs and CTs in that tissue. The enzyme kinetics studies showed proteolytic activity in dentin extracts for both classes of proteases. Furthermore, it was observed that, at least for sound human dentin matrices, the activity of MMPs seems to be predominant over the CTs one.     

Inhibition of dentin matrix‐bound cysteine cathepsins by potassium fluoride

Matrix metalloproteinases (MMPs) and cysteine cathepsins (CCs) can break down unprotected type I collagen fibrils in dentin matrix. This study investigated the use of potassium fluoride (KF) as a potential inhibitor of MMPs and CCs in dentin. Demineralized dentin beams were divided into groups (n = 10 in each group) and incubated in artificial saliva (AS, control), either alone or with one of seven concentrations of KF (6–238 mM fluoride) for 1, 7, and 21 d. After 21 d, all groups were further aged in AS for 6 months. Total MMP activity was screened using the colorimetric MMP assay. The activities of MMP‐2 and MMP‐9 were investigated using gelatin zymography. At the end of each incubation, changes in loss of dry mass and CC‐mediated or total dissolution of collagen peptides were measured via precision weighing, C‐terminal crosslinked telopeptide of type I collagen (CTX), and hydroxyproline (HYP) assays. The beams were examined using scanning electron microscopy. After 21 d, total MMP activities, dry mass loss, and CTX release for the groups exposed to 179 and 238 mM fluoride were significantly lower compared with the control group. After 6 months, all groups showed similar total MMP activity, dry mass loss, and HYP release, and CTX levels were significantly lower when the fluoride concentration was ≥24 mM. Calcium fluoride (CaF₂)‐like precipitates were observed over the beams. In summary, KF significantly inhibited the catalytic activity of dentin matrix‐bound CCs but did not seem to be effective for MMP‐mediated activity.     

Chlorhexidine spray versus mouthwash in the control of dental plaque after implant surgery

BACKGROUND/PURPOSE: This randomized clinical trial was aimed at comparing two different means of delivering chlorhexidine digluconate (CHX) for plaque control during the 2 weeks following implant surgery. MATERIALS AND METHODS: Twenty patients selected for implant therapy were randomly divided into two groups: 10 subjects used 15 ml of 0.12% CHX mouthrinse (control group) and 10 used 0.2% CHX spray (test group). Professional oral hygiene was carried out immediately before surgery. During the 14 days following surgery mechanical oral hygiene was performed only at the teeth not surgically involved. Plaque index (PI), stain index (SI), modified gingival index and taste alteration were assessed on the 7th and 14th day after surgery. The clinical parameters were evaluated at four tooth surfaces by a single examiner. Teeth proximal to surgical site and teeth not involved were statistically compared. RESULTS: In both groups, the PI increased similarly, with respect to the baseline, at days 7 and 14. There was no significant difference between the two groups at either time point. On the contrary, in the control group, the SI increased significantly when compared with baseline over the 14 days both at teeth nearest to surgical sites and at not-involved sites. In the test group pigmentation was consistent only at teeth proximal to the surgical site. When considering not-involved sites, tooth staining was significantly lower in the test with respect to the control group. CONCLUSIONS: The present study indicates that the efficacy of CHX spray in the post-surgical control of dental plaque is similar to that of CHX mouthwash. Tooth staining, however, is significantly lower in the spray group at sites not surgically involved. These effects might be related to the route of CHX delivery, as well as the total dose administered that was significantly lower in the spray group with respect to the rinse group.     

Chlorhexidine rinse in prevention of dental caries in patients following radiation therapy

Patients who receive cancer radiotherapy, which compromises salivary gland function, may develop xerostomia. These patients are at increased risk to develop rampant dental caries. Streptococcus mutans and species of lactobacillus have been associated with dental caries. Quantitative counts of these organisms demonstrated high caries risk in 85% of patients studied. The use of chlorhexidine rinse to reduce the counts of S. mutans and lactobacillus was studied. A modest reduction in S. mutans was seen, but little effect was demonstrated on lactobacillus counts. Caries activity was shown to be related to lactobacillus count.     

Chlorhexidine spray versus chlorhexidine mouthwash in the control of dental plaque after periodontal surgery

BACKGROUND/AIMS: This clinical trial aimed at comparing 2 different means of delivering chlorhexidine digluconate (CHX) in the oral hygiene phase during the 2 weeks following periodontal surgery. METHOD: 40 patients were randomly divided into 2 groups: A (using CHX mouthwash) and B (using CHX spray). Professional oral hygiene was carried out immediately before surgical operation. For 7 days after surgery, group A used CHX mouthwash and group B CHX spray on the teeth involved in the surgical procedure, while mechanical oral hygiene was maintained only on the teeth not involved surgically. After suture removal, on the 7th day, patients were allowed to perform mechanical oral hygiene also on surgical sites. Plaque index (PI) and stain index (SI) were evaluated on the 7th and 14th days after the operation. RESULTS: In both groups, PI increased similarly with respect to the baseline in surgically involved teeth, being 0.25+/-0.41 (SD) and 0.15+/-0.26, respectively, in A and B, on day 7, and 0.14+/-0.23 (A) and 0.10+/-0.22 (B), on day 14. There was no significant difference between A and B on either day 7 or 14. On the contrary, SI increased significantly in respect to the baseline over the 14 days in group A at both involved and not involved sites, while it did not differ from the baseline in group B. CONCLUSIONS: The present results indicate that the efficacy of CHX spray in the post-surgical control of dental plaque is not different from that of CHX mouthwash. Tooth staining, on the contrary, was significantly lower in the group using CHX spray. The observed effects might be related to the way of delivering CHX and to the total dose administered, about 80% lower in group B in respect to A. Further studies are needed to validate the preliminary findings of the present study.     

Chlorhexidine concentration in saliva after topical treatment with an antibacterial dental varnish

PURPOSE: To evaluate the salivary levels of chlorhexidine (CHX) after a single professional treatment with an antibacterial dental varnish (Cervitec) containing 1% CHX and 1% thymol. METHODS: Unstimulated whole saliva from 21 healthy young adults was collected at baseline and up to 24 hours after treatment at designated time intervals and the CHX levels in saliva were quantified with high-performance liquid chromatography. Post-treatment saliva samples were added to suspensions of mutans streptococci and supragingival dental plaque for a growth inhibition. RESULTS: CHX concentration in saliva showed a peak value (76.5 microg/ml) after 5 minutes followed by a slow decrease with time. The elevation was statistically significant (P < 0.05) up to 4 hours after the application of the varnish and the recorded values were back to baseline levels after 24 hours. The 2- and 4-hour post-treatment saliva samples inhibited growth of mutans streptococci by 46% and 33%, respectively.     

Chlorhexidine spray as an adjunct in the control of dental biofilm in children with special needs

The aim of this study was to evaluate the clinical effectiveness of .12% chlorhexidine applied via spray and the acceptance. A total of 26 individuals with mental health issues, aged 7–14, were included into two groups: placebo (control, n = 13) and chlorhexidine (experimental, n = 13). Both groups received two daily applications of spray during 2 months. The periodontal conditions were evaluated by the simplified oral hygiene index (OHI‐S) and gingival index (GI). The evaluation of acceptance of the application method (spray) was assessed by questionnaire. Data were analyzed with nonparametric tests, with a significance level of 5%. Regarding the OHI‐S index, only the experimental group showed significant change during the evaluations (p < 0.001). Regarding the GI, both groups showed significant changes during the evaluations. The method of application was well accepted by patients and caregivers, and .12% chlorhexidine solution applied via spray significantly reduced the rates of dental and gingival biofilm.     

Nicotine inhibits mineralization of human dental pulp cells

Nicotine is a major component of tobacco smoke, and signals via nicotinic acetylcholine receptors (nAChR). However, little is known about the effects of nicotine on human dental pulp cells (HDPCs). In this study, we assessed the effects of nicotine on mineralization in HDPCs. We confirmed messenger RNA expression of nAChR subunits and examined the effects of nicotine on expression of extracellular matrices (ECMs), alkaline phosphatase (ALP) activity, and mineralized nodule formation by HDPCs. Gene expression of nAChR subunits alpha1, alpha2, alpha 4, alpha 5, alpha 6, alpha 7, beta1, beta2, and beta 4 was detected in HDPCs. Interestingly, the messenger RNA expression of dentin matrix acidic phosphoprotein-1, bone sialoprotein, and ALP activity were significantly reduced in nicotine-treated HDPC. In addition, mineralized nodule formation, which was examined by alizarin red staining, was also inhibited in HDPCs by the same treatment. These results indicate that nicotine suppresses the cytodifferentiation and mineralization of HDPCs, possibly via nAChR.     

The activity package of the dental assistant

The aim of this study was to assess the package of activities that is actually carried out by the chairside assistant, and the activities that should be dropped or added to the package, according to both assistants and dentists. A representative sample of 1034 dentists and their assistants received a questionnaire. Results showed large differences between assistants in kind and number of activities actually carried out. Part of the group of assistants as well as part of the group of dentists expressed their wish to extend the package of activities.     

Eugenol inhibits sodium currents in dental afferent neurons

Although eugenol is widely used in dentistry, little is known about the molecular mechanisms responsible for its anesthetic properties. In addition to calcium channels, recently demonstrated by our group, there could be another molecular target for eugenol. Using a whole-cell patch-clamp technique, we investigated the effect of eugenol on voltage-gated sodium channel currents (I(Na)) in rat dental primary afferent neurons identified by retrograde labeling with a fluorescent dye in maxillary molars. Eugenol inhibited action potentials and I(Na) in both capsaicin-sensitive and capsaicin-insensitive neurons. The pre-treatment with capsazepine, a competitive antagonist of transient receptor potential vanilloid 1 (TRPV1), failed to block the inhibitory effect of eugenol on I(Na), suggesting no involvement of TRPV1. Two types of I(Na), tetrodotoxin (TTX)-resistant and TTX-sensitive I(Na), were inhibited by eugenol. Our results demonstrated that eugenol inhibits I(Na) in a TRPV1-independent manner. We suggest that I(Na) inhibition by eugenol contributes to its analgesic effect.     

Eugenol inhibits calcium currents in dental afferent neurons

Eugenol is a topical analgesic agent widely used in the dental clinic. To elucidate the molecular mechanism underlying its analgesic action, we investigated the effect of eugenol on high-voltage-activated calcium channel (HVACC) currents in dental primary afferent neurons, and with a heterologous expression system. Dental primary afferent neurons were identified by retrograde labeling with a fluorescent dye, DiI. Eugenol inhibited HVACC currents in both capsaicin-sensitive and capsaicin-insensitive dental primary afferent neurons. The HVACC inhibition by eugenol was not blocked by capsazepine, a competitive transient receptor potential vanilloid 1 (TRPV1) antagonist. Eugenol inhibited N-type calcium currents in the cell line C2D7, stably expressing the human N-type calcium channels, where TRPV1 was not endogenously expressed. Our results suggest that the HVACC inhibition by eugenol in dental primary afferent neurons, which is not mediated by TRPV1 activation, might contribute to eugenol's analgesic effect. Abbreviations: high-voltage-activated calcium channel, HVACC; transient receptor potential vanilloid 1, TRPV1; trigeminal ganglion, TG; dorsal root ganglion, DRG; capsazepine, CZP.