Mitsue Fujimaki

Photosensitizer and light diffusion through dentin in photodynamic therapy

Abstract. Photodynamic therapy has been considered a potential antimicrobial modality against oral infections, including dental caries. A model to estimate the penetration of both photosensitizers and light through human dentin, a factor of interest in photodynamic therapy, is proposed. The photoacoustic spectroscopy technique was used to evaluate in vitro dentin permeability of three different photosensitizers. Using the dentin optical absorption and scattering coefficients, it was possible to propose a semi-quantitative model predicting both photosensitizer and light doses within dentin. The graphic illustrations obtained provided guidelines that may be useful in photodynamic therapy protocols used as antimicrobial tools in caries lesions.

Factors That Drive Dentists towards or Away from Dental Caries Preventive Measures: Systematic Review and Metasummary

Background Dental caries is a serious public health concern. The high cost of dental treatment can be avoided by effective preventive measures, which are dependent on dentists’ adherence. This study aimed to evaluate the factors that drive dentists towards or away from dental caries preventive measures. Methods and Findings This systematic review was registered in PROSPERO (CRD42012002235). Several databases as well as the reference lists and citations of the included publications were searched according to PRISMA guidelines, yielding 18,276 titles and abstracts, which were assessed to determine study eligibility. Seven qualitative studies and 41 surveys (36,501 participants) remained after data extraction and interpretation. A total of 43 findings were abstracted from the reports and were grouped together into 6 categories that were judged to be topically similar: education and training, personal beliefs, work conditions, remuneration, gender, place of residence and patients. The main findings for adherence based on their calculated frequency effect sizes (ES) were teamwork (21%) and post-graduation (12%), while for non-adherence were biologicism (27%), and remuneration for preventive procedures (25%). Intensity ES were also calculated and demonstrated low prevalence of the findings. Quality assessment of the studies demonstrated that the methodological quality, particularly of surveys, varied widely among studies. Conclusions Despite the questionable quality of the included reports, the evidence that emerged seems to indicate that further education and training coupled with a fairer pay scheme would be a reasonable approach to change the balance in favor of the provision of dental caries preventive measures by dentists. The results of this review could be of value in the planning and decision making processes aimed at encouraging changes in professional dental practice that could result in the improvement of the oral health care provided to the population in general.

Singlet oxygen production by combining erythrosine and halogen light for photodynamic inactivation of Streptococcus mutans

BACKGROUND Photodynamic inactivation of microorganisms is based on a photosensitizing substance which, in the presence of light and molecular oxygen, produces singlet oxygen, a toxic agent to microorganisms and tumor cells. This study aimed to evaluate singlet oxygen quantum yield of erythrosine solutions illuminated with a halogen light source in comparison to a LED array (control), and the photodynamic effect of erythrosine dye in association with the halogen light source on Streptococcus mutans. METHODS Singlet oxygen quantum yield of erythrosine solutions was quantified using uric acid as a chemical-probe in an aqueous solution. The in vitro effect of the photodynamic antimicrobial activity of erythrosine in association with the halogen photopolimerizing light on Streptococcus mutans (UA 159) was assessed during one minute. Bacterial cultures treated with erythrosine alone served as negative control. RESULTS Singlet oxygen with 24% and 2.8% degradation of uric acid in one minute and a quantum yield of 0.59 and 0.63 was obtained for the erythrosine samples illuminated with the halogen light and the LED array, respectively. The bacterial cultures with erythrosine illuminated with the halogen light presented a decreased number of CFU mL(-1) in comparison with the negative control, with minimal inhibitory concentrations between 0.312 and 0.156mgmL(-1). CONCLUSIONS The photodynamic response of erythrosine induced by the halogen light was capable of killing S. mutans. Clinical trials should be conducted to better ascertain the use of erythrosine in association with halogen light source for the treatment of dental caries.

Fluoride concentrations in the water of Maringá, Brazil, considering the benefit/risk balance of caries and fluorosis

Current Brazilian law regarding water fluoridation classification is dichotomous with respect to the risks of and benefits for oral diseases, and fluoride (F) concentrations less than 0.6 or above 0.8 mg F/L are considered outside the normal limits. Thus, the law does not consider that both caries and fluorosis are dependent on the dosage and duration of fluoride exposure because they are both chronic diseases. Therefore, this study evaluated the quality of water fluoridation in Maringá, PR, Brazil, considering a new classification for the concentration of F in water the supply, based on the anticaries benefit and risk of fluorosis (CECOL/USP, 2011). Water samples (n = 325) were collected monthly over one year from 28 distribution water networks: 20 from treatment plants and 8 from artesian wells. F concentrations were determined using a specific ion electrode. The average F concentration was 0.77 mg F/L (ppm F), ranging from 0.44 to 1.22 mg F/L. Considering all of the water samples analyzed, 83.7% of them presented from 0.55 to 0.84 mg F/L, and according to the new classification used, they would provide maximum anticaries benefit with a low risk of fluorosis. This percentage was lower (75.4%) in the water samples supplied from artesian wells than from those distributed by the treatment plant (86%). In conclusion, based on the new classification of water F concentrations, the quality of water fluoridation in Maringá is adequate and is within the range of the best balance between risk and benefit.

Evaluation of photosensitizer penetration into sound and decayed dentin: A photoacoustic spectroscopy study

BACKGROUND Photodynamic therapy (PDT) may have topical indications. In those cases it is important for a topical photosensitizer to penetrate into the tissue to which it has been applied. This study aimed to compare the penetration of two different concentrations of erythrosine into intact and in vitro decayed dentin samples. METHODS This in vitro study evaluated erythrosine (0.3 and 5%) penetration into sound (intact) and decayed dentin. A total of 11 dentin discs were prepared and divided into two equal halves, in order to keep one half sound while the other half was submitted to sterilization and an in vitro demineralization model for 5 days. Before erythrosine application, the organic and inorganic composition of all samples was evaluated by Fourier Transform Raman spectroscopy, and after erythrosine application for 30 min, the penetration depth was determined by Photoacoustic spectroscopy technique. RESULTS The results indicated that 0.3% erythrosine showed a higher penetration depth into sound dentin (p = 0.002); and 5% erythrosine higher penetration into decayed dentin (p < 0.001). However considering clinical parameters, no statistically significant difference was found between any of the conditions tested. CONCLUSIONS Erythrosine demonstrated ability to penetrate into dentin, irrespective of sound or decayed condition. Photoacoustic spectroscopy can be considered a method for estimating the penetration into hard tissues, and in conjunction with Raman spectroscopy, these are effective methods for evaluating the spectral response of dentin. Considering that erythrosine is capable of penetrating into decayed dentin, clinical trials are needed to test the effectiveness of this photosensitizer in Photodynamic therapy and Antimicrobial Photodynamic therapy.

Susceptibility to Coffee Staining during Enamel Remineralization Following the In-Office Bleaching Technique: An In Situ Assessment.

PURPOSE To assess in situ the enamel mineralization level and susceptibility to coffee staining after in-office bleaching. MATERIALS AND METHODS Thirty-six human dental fragments assembled into intraoral devices were bleached with 35% hydrogen peroxide and treated as follows: (group 1) no contact with coffee; (group 2) immersion in a coffee solution for 30 minutes daily for 7 days, starting 1 week after bleaching; and (group 3) immersion in a coffee solution for 30 minutes daily for 14 days, starting immediately after bleaching. Enamel mineralization and color were assessed before bleaching (T1), immediately after bleaching (T2), and after 7 (T3) and 14 days (T4). The CIE whiteness index (W*) and closeness to white (ΔW*) following bleaching and/or immersion in coffee were calculated. Data were analyzed with Friedman and Wilcoxon tests or Kruskal-Wallis and Mann-Whitney U-tests (α = 0.05). RESULTS Significant differences in the mineralization levels were observed as a function of time. No significant differences in W* were observed between groups, nor was W* significantly different at T3 and T4. Similar ΔW* was observed between groups after 7 or 14 days. CONCLUSIONS The mineral loss after in-office bleaching was progressively reversed by contact with saliva for 14 days. The whiteness index was not affected by contact with coffee during the remineralization period. CLINICAL SIGNIFICANCE The results of this in situ study suggest that the mineral loss caused by in-office dental bleaching is minimal and is partly compensated by remineralization due to contact with saliva. Additionally, whiteness was not affected by daily exposition to coffee during the enamel remineralization, which indicates that avoiding the consumption of coffee immediately following in-office bleaching is unnecessary. (J Esthet Restor Dent 28:S23-S31, 2016).

In vitro effect of energy drinks on human enamel surface

Introduction: Energy drinks (ED) possess low pH and citric acid in their composition, making them potentially erosive beverages that can contribute to the high dental erosion rates found currently in the general population and also in young people. Objective: To evaluate the mean pH and titratable acidity of commercial ED and the influence of a brand of ED on the superficial microhardness of human enamel. Material and method: Ten commercial ED were selected and the pH of two lots of each ED with and without gas was obtained. Acid titration was conducted with the addition of NaOH aliquots until the pH 7 was reached. Eighteen human enamel specimens were allocated in three groups (N=6), Red Bull (RB), Red Bull Light (RBL) and distilled water (C), submitted to an acid challenge with the ED, six consecutive times, with 12 hours intervals, during three days. Knoop microhardness was measured before and after the acid challenge. Result: All ED brands tested presented low pH levels ranging from 2.1 to 3.2. Regarding titratable acidity, it was found that the amount of base required promoting the neutralization of the solutions ranged from 1200μL to 3750μL. Samples of human enamel in the RB and RBL groups submitted to the acid challenge presented significantly decreased Knoop microhardness when compared with the group C. Conclusion: All ED examined have potential to promote mineral loss due to the low pH and high titratable acidity. The ED analyzed promoted significant mineral losses on the dental enamel surface. Descriptors: Tooth erosion; energy drinks; dental enamel; tooth demineralization.

Survival analysis of ART restorations in primary molars of preschool children: 1 year follow-up

Among the minimally invasive approaches available today, the atraumatic restorative treatment (ART) has demonstrated promising results both in the primary and permanent dentition. Objective: To evaluate the survival of Class I ART restorations in preschoolers with two Brazilian brands of glass ionomer cements (GIC) in comparison with a reference GIC. Material and method: The cavities of 49 preschool children (three to five years) with carious lesions in the posterior teeth (N=81) were filled by two experienced pediatric dentists according to the ART technique. The Brazilian GICs Maxxion-R (MR) and Vitro-Fil LC (VF), and the reference GIC Ketac-Molar (KM) were placed in a randomly pre-established sequence. Restorations were evaluated after 6 and 12 months by another investigator. Scores 0 and 1 were considered successful, while scores 3-9 were classified as failures. Kaplan-Meier survival analysis and the log-rank test were performed (p<0.05). Result: No statistically significant differences in survival rates of the tested GIC were observed after 12 months. Conclusion: The clinical performance the low-cost Brazilian GICs MR and VF observed after 12 months suggests that they may be an alternative for Class I ART restorations to safeguard the natural exfoliation of primary teeth. However, until further studies involving a larger number of restorations and longer follow-up periods are conducted, reference GIC such as KM should continue to be the material of choice for ART restorations. Descriptors: Dental atraumatic restorative treatment; glass ionomer cements; clinical trial. Rev Odontol UNESP. 2018 Mar-Apr; 47(2): 112-118 Survival analysis of ART restorations... 113 113/118

Antimicrobial effect of photodynamic therapy using erythrosine/methylene blue combination on Streptococcus mutans biofilm

BACKGROUND Photodynamic therapy (PDT) has demonstrated promising results in the treatment of several clinical pathologies through the photochemical reaction caused by the combination of a photosensitizer and a light source. The objective of this study was to evaluate the antimicrobial effect of the combination of the photosensitizers (PSs) erythrosine/methylene blue activated by a white halogen light device on Streptococcus mutans biofilm. METHODS Two separate experiments were conducted, the first using the PSs at the concentration of 100 μM, and the second 250 μM. The PSs were tested on S. mutans biofilms cultured for 24 h in isolation, in combination, with and without light activation for 2 min fractionated in 4 periods of 30 s. After treatment, biofilms were diluted and plated on BHI medium and incubated for 24 h for colony forming units (CFU) counting. The results (log10) were analyzed with ANOVA followed by Tukey test (p < 0.05). RESULTS The erythrosine/methylene blue combination activated by white halogen light at 100 and 250 μM, and erythrosine at 250 μM, methylene blue at 250 μM presented significantly reduced cell counts (3.2 log10, 5.3 log10, 4.5 log10, 4.3 log10, respectively) when compared to controls (p < 0.05). CONCLUSION PDT with the combination of erythrosine/methylene blue demonstrated better results that the PSs in isolation regardless of the concentration. The use of this combination at the concentration of 250 μM shows promise as an antibacterial treatment for carious lesions and should be further assessed.

Beyond the discourse of amalgam vs composite resin restorations

OBJECTIVE: To diagnose the prevalence of amalgam and resin composite restorations performed by professionals in public service and university students in a municipality in the Northeast of the State of Parana.METHODS: Ten basic health units were randomly selected, at which 500 clinical record charts of patients of both sexes aged from 18 to 50 years were consulted. To analyze the prevalence of restorations performed by students, a questionnaire was applied to 4th and 5th year students, containing questions relative to the number of restorations and type of material using in intramural clinical activities.RESULTS: In the basic health units, 66% of restorations were performed with amalgam, and 34% with resin composite. At the dental school, 4th year students responded that when they were in the 3rd year, out of a total of 367 restorations, 21.5% were performed with amalgam and 78.5% with resin composite. For the 5th year group of students, the percentage of teeth restored with amalgam was 14.3%, 12.0% and10.2%, when they were in the 3rd, 4the and 5th years of the course, respectively. The results obtained revealed that the indication of the restoration material differed in the two scenarios.CONCLUSION: In the basic health units, the majority of restorations were performed with amalgam, whereas at the dental school there was higher prevalence of resin composite restorations. One must reflect whether professional education has adequately developed the necessary competencies for decision making and meeting the needs of this population.