Melissa Thiemi Kato

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% TiF4 varnish compared to commercial NaF and NaF/CaF2 varnishes and 4% TiF4 solution on enamel erosion. For this, 72 bovine enamel specimens were randomly allocated to the following treatments: NaF varnish(2.26% F), NaF/CaF2 varnish (5.63% F), 4% TiF4 varnish (2.45% F), F-free placebo varnish, 4% TiF4 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°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 (α = 0.05). The mean daily erosion increments and cumulative erosion (micrometers) were significantly less for the TiF4 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/CaF2 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), TiF4 solution (0.86 ± 0.11/ 2.05 ± 1.49) and control (0.77 ± 0.16/2.06 ± 1.49). In conclusion, the TiF4 varnish seems to be a promising treatment to reduce enamel loss under mild erosive conditions.

TENS and low-level laser therapy in the management of temporomandibular disorders

Pain relief and reestablishment of normal jaw function are the main goals of conservative management of Temporomandibular Disorders (TMD). Transcutaneous electrical nerve stimulation (TENS) and laser therapy are part of these modalities, although little is known about their real efficacy in controlled studies. This research compared these two treatments in a sample of 18 patients with chronic TMD of muscular origin, divided into two groups (LASER and TENS). Treatment consisted of ten sessions, in a period of 30 days. Active range of motion (AROM), visual analogue scale (VAS) of pain and muscle (masseter and anterior temporalis) palpation were used for follow-up analysis. Data were analyzed by Friedman test and ANOVA for repeated measurements. Results showed decrease in pain and increase in AROM for both groups (p<0.05), and improvement in muscle tenderness for the LASER group. Authors concluded that both therapies are effective as part of TMD management and a cumulative effect may be responsible for the improvement. Caution is suggested when analyzing these results because of the self-limiting feature of musculoskeletal conditions like TMD.

Gels Containing MMP Inhibitors Prevent Dental Erosion in situ

Matrix metalloproteinase (MMP) inhibition has been shown to reduce dentin caries progression, but its role in dental erosion has not yet been assessed. This study tested the hypothesis that gels containing MMP inhibitors (epigallocatechin gallate-EGCG and chlorhexidine) can prevent dental erosion. Volunteers (n = 10) wore palatal devices containing bovine dentin blocks (n = 10/group) treated for 1 min with EGCG at 10 (EGCG10) or 400 µM (EGCG400), chlorhexidine at 0.012%, F at 1.23% (NaF), and no vehicle (placebo). Erosion was performed with Coca-Cola® (5 min) 4X/day during 5 days. The wear, assessed by profilometry (mean ± SD, µm), was significantly reduced by the gels containing MMP inhibitors (0.05 ± 0.02a, 0.04 ± 0.02a, and 0.05 ± 0.02a for EGCG10, EGCG400, and chlorhexidine, respectively) when compared with NaF (0.79 ± 0.35b) and placebo gels (1.77 ± 0.35b) (Friedman and Dunn’s tests, p < 0.01). The use of gels delivering MMP inhibitors was shown to prevent erosion and opens a new perspective for protection against dental erosion.

Impact of Protease Inhibitors on Dentin Matrix Degradation by Collagenase

This proof-of-concept study assessed whether the reduction of the degradation of the demineralized organic matrix (DOM) by pre-treatment with protease inhibitors (PI) is effective against dentin matrix loss. Bovine dentin slices were demineralized with 0.87 M citric acid, pH 2.3, for 36 hrs. In sequence, specimens were treated or not (UT, untreated) for 1 min with gels containing epigallocatechin 3-gallate (EGCG, 400 µM), chlorhexidine (CHX, 0.012%), FeSO4 (1 mM), NaF (1.23%), or no active compound (P, placebo). Specimens were then stored in artificial saliva (5 days, 37°C) with the addition of collagenase (Clostridium histolyticum, 100 U/mL). We analyzed collagen degradation by assaying hydroxyproline (HYP) in the incubation solutions (n = 5) and evaluated the dentin matrix loss by profilometry (n = 12). Data were analyzed by ANOVA and Tukey’s test (p < 0.05). Treatment with gels containing EGCG, CHX, or FeSO4 led to significantly lower HYP concentrations in solution and dentin matrix loss when compared with the other treatments. These results strongly suggest that the preventive effects of the PI tested against dentin erosion are due to their ability to reduce the degradation of the DOM.

Protective effect of green tea on dentin erosion and abrasion

Objective: This in situ study evaluated the protective effect of green tea on dentin erosion (ERO) and erosion-abrasion (ABR). Material and methods: Ten volunteers wore intraoral palatal appliances with bovine dentin specimens subjected to ERO or ERO + toothbrushing abrasion performed immediately (ERO+I-ABR) or 30 min after erosion (ERO+30-min-ABR). During 2 experimental 5-day crossover phases, the volunteers rinsed with green tea or water (control, 1 min) between each erosive (5 min, cola drink) and abrasive challenge (30 s, toothbrushing), 4x/day. Dentin wear was measured by profilometry. Results: The green tea reduced the dentin wear significantly for all conditions compared to control. ERO+I-ABR led to significantly higher wear than ERO, but it was not significantly different from ERO+30-min-ABR. ERO+30-min-ABR provoked significant higher wear than ERO, only for the placebo treatment. Conclusions: From the results of the present study, it may be concluded that green tea reduces the dentin wear under erosive/abrasive conditions.

The Role of Matrix Metalloproteinases in Dental Erosion

This review discusses the role of matrix metalloproteinases (MMPs) in the development of dentin erosion and the protective effects of MMP inhibitors, based on recent evidence from in vitro and in situ studies. MMPs are present in both dentin and saliva and play an important role in dentin erosion progression. Enzymatic removal of the organic matrix by MMPs increases the demineralization process, since the demineralized organic matrix has been shown to hamper ionic diffusion after an acidic challenge. Recent evidence from in vitro and in situ studies has shown a protective role of MMP inhibitors against dentin erosion and erosion plus abrasion. The inhibitors tested were green tea and its active epigallocatechin-gallate (EGCG), ferrous sulfate, and chlorhexidine. They have been tested in dentifrices, solutions, and gels. The latter led to a more pronounced protective effect against dentin erosion and erosion plus abrasion. The protection was long-lasting and could be observed after up to 10 days of severe erosive and erosive-plus-abrasive challenges in situ. Thus, the use of MMP inhibitors has emerged as an important preventive tool against dentin erosion. Clinical studies should be conducted to confirm the results obtained and to give support to the establishment of clinical protocols of use.

Effect of Iron on Matrix Metalloproteinase Inhibition and on the Prevention of Dentine Erosion

It is known that some metal salts can inhibit matrix metalloproteinase (MMP) activity, but the effect of iron has not been tested yet. On the other hand, it has recently been suggested that MMP inhibition might influence dentine erosion. Based on this, the aims of this study were: (1) to test in vitro the effect of FeSO4 on MMP-2 and -9 activity, and (2) to evaluate in situ the effect of FeSO4 gel on dentine erosion. MMP-2 and -9 activities were analysed zymographically in buffers containing FeSO4 in concentrations ranging between 0.05 and 1.5 mmol/l or not. Volunteers (n = 10) wore devices containing bovine dentine blocks (n = 60) previously treated with the following gel treatments: FeSO4 (1 mmol/l FeSO4), F (NaF 1.23%; positive control) and placebo (negative control). The gels were applied once and removed after 1 min. Erosion was performed extraorally with Coca-Cola 4 times per day for 5 min over 5 days. Dentine wear was evaluated by profilometry. The data were analysed by Kruskal-Wallis and Dunn’s tests (p < 0.05). FeSO4 inhibited both MMP-2 (IC50 = 0.75 mmol/l) and MMP-9 (IC50 = 0.50 mmol/l) activities. In the in situexperiment, the mean wear (± SD) found for the F gel (0.79 ± 0.08 µm) was significantly reduced in more than 50% when compared to the placebo gel (1.77 ± 0.33 µm), but the FeSO4 gel completely inhibited the wear (0.05 ± 0.02 µm). Since FeSO4 was able to inhibit MMP in vitro, it is possible that the prevention of dentine wear by the FeSO4 gel in situ might be due to MMP inhibition, which should be investigated in further studies.

Preventive effect of commercial desensitizing toothpastes on bovine enamel erosion in vitro.

This study evaluated in vitro commercial desensitizing toothpastes with respect to the prevention of erosion and explored the effect of their agents alone or in combination with fluoride. Bovine enamel blocks were randomly allocated to five groups of 20 and exposed to: Sensodyne ProNamel (1,425 ppm F as NaF, 5% KNO3), Sensodyne Original (no fluoride, 10% SrCl2), Colgate Sensitive (1,450 ppm F as sodium monofluorophosphate, 5% K citrate), Crest (fluoride-only toothpaste, 1,100 ppm F as NaF) and water (negative control). A second experiment was conducted with experimental dentifrices containing fluoride (NaF, 1,100 ppm F), 10% SrCl2, 5% KNO3 or 5% K citrate alone or the latter three combined with F. The samples were submitted to four cycles, alternating demineralization (cola, 10 min) and remineralization (artificial saliva, 1 h). Before and between cyclic de- and remineralization, blocks were treated with slurries of the respective toothpastes or water (1 min). Erosive tissue loss was analyzed by profilometry. Data were analyzed by Kruskal-Wallis and Dunn’s tests (p < 0.05). The mean erosion depth (± SE, µm) was significantly less for Colgate Sensitive (0.04 ± 0.00), Sensodyne Original (0.06 ± 0.01) and Crest (0.07 ± 0.01) than for Sensodyne ProNamel (2.36 ± 0.25) or water (2.92 ± 0.24), which did not significantly differ from each other. Both F and the desensitizing agents alone reduced erosion, but no additive effect was found. In addition, the combination of F and KNO3 did not reduce erosion. These in vitro results suggest that the presence of fluoride or desensitizing substances in toothpastes, alone or in combination, can reduce erosion of enamel, but this is not valid for all the formulations.

Sodium Fluoride Inhibits MMP-2 and MMP-9

The importance of fluoride (F) in preventing dental caries by favorably interfering in the demineralization-remineralization processes is well-established, but its ability to inhibit matrix metalloproteinases (MMPs), which could also help to prevent dentin caries, has not been investigated. This study assessed the ability of F to inhibit salivary and purified human gelatinases MMPs-2 and -9. Saliva was collected from 10 healthy individuals. Pooled saliva was centrifuged, and supernatants were incubated for 1 hr at 37°C and subjected to zymography. Sodium fluoride (50-275 ppm F) was added to the incubation buffer. The reversibility of the inhibition of MMPs-2 and -9 by NaF was tested by the addition of NaF (250-5,000 ppm F) to the incubation buffer, after which an additional incubation was performed in the absence of F. F decreased the activities of pro- and active forms of salivary and purified human MMPs in a dose-response manner. Purified gelatinases were completely inhibited by 200 ppm F (IC50 = 100 and 75 ppm F for MMPs-2 and -9, respectively), and salivary MMP-9 by 275 ppm F (IC50 = 200 ppm F). Inhibition was partially reversible at 250-1,500 ppm F, but was irreversible at 5,000 ppm F. This is the first study to describe the ability of NaF to inhibit MMPs completely.

Evaluation of the efficacy of low-level laser therapy (LLLT) and the microelectric neurostimulation (MENS) in the treatment of myogenic temporomandibular disorders: a randomized clinical trial

OBJECTIVE The aim of the present study was to evaluate the efficacy of low-level laser therapy (LLLT) and the microelectric neurostimulation (MENS) in the treatment of patients with temporomandibular disorders (TMD). MATERIAL AND METHODS A sample of 19 individuals presenting with signs and symptoms of myogenic TMD was randomly divided into two groups (I - LLLT and II - MENS). Therapy was done in 10 sessions, three times a week, for one month. Patients were evaluated by the Visual Analogue Scale (VAS), measurement of active range of motion (AROM) and muscle palpation, performed immediately before and 5 minutes after each therapeutic session by a blinded TMD specialist. The ANOVA for repeated measurements and Mann-Whitney tests were used for the statistical analysis. RESULTS The results showed an increase in maximum mouth opening and a decrease in tenderness to palpation for both groups. The VAS reduced for both groups, although more evident for the laser group (p<0.05). CONCLUSION Authors concluded that both therapies were effective as part of the TMD treatment, and the cumulative effect may have been responsible for this fact. However, caution is recommended when judging the results due to the self-limiting aspect of musculoskeletal conditions such as TMD.