In vitro Assessment of Thermal Changes in Human Teeth during Photodynamic Antimicrobial Chemotherapy Performed with Red Light Sources

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Photo-disinfection of deep dentin caries lesions may be a useful tool for preserving tooth structure. However, increase of pulpal temperature higher than 5.5 degrees C may put pulp vitality in danger. Objectives: This in vitro study evaluated thermal effects of radiation of the red spectrum (lambda = 600-700 nm, 94 J cm(-2)) on pulpal and periodontal areas when irradiating deep dentin cavities in human teeth. Methods: Tooth preparation was performed at occlusal surface in 10 human teeth, which were irradiated by five different light units, four diode GaAlAs lasers: Coherent (C); Kondortech (B); Whitening lase (W); and K5000 with 2 different tips (K1 and K2), as well as one light emitting diode Laserbeam (LED). After application of toluidine blue O dye in the cavity, variation of temperature was measured in duplicate using a digital thermometer and 2 K-type thermocouples one placed inside the pulpal chamber and the other on root surface at the cementoenamel junction, simultaneously. The mean average temperature rise (Delta T) was calculated for each group. Results: Delta T values were analyzed by ANOVA and Tukey tests. Pulpal temperature increase ranged from 0.62 +/- 0.51 to 1.25 +/- 0.50 degrees C. Group C presented the highest Delta T, which was statistically significant different from B, K1, and K2. The lowest Delta T value was found for group K2, which statistically differed from the group W. No other statistically significant difference was found. At the root surface, Delta T values were lower than 0.5 degrees C for all devices and no statistically significantly difference was found among them. Conclusion: With regard to thermal side effects, the use of these red light sources operating at 94 J cm(-2) may be considered harmless for dental tissues.20614751480Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CNPq [620160/2006-3

CO2 laser and fluoride on the inhibition of root caries-an in vitro microbial model

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)An increase in the dental caries prevalence on root surfaces has been observed mainly in elderly. This research assessed, in vitro, the effectiveness of a pulsed CO2 (lambda = 10.6 mu m) laser associated or not with fluoride, in reducing human root dentine demineralization in conditions that mimic an oral high cariogenic challenge. After sterilization, root dentine specimens were randomly assigned into 6 groups (n = 30), in triplicate. The groups were Control (C), Streptococcus mutans (SM), Fluoride (F), Laser (L), Fluoride + laser (FL), and Laser + fluoride (LF). Except for the control group, all the specimens were inoculated with SM and immersed 3 times a day in a 40% sucrose bath. After a 7-day cariogenic challenge, the mineral loss and lesion depth were evaluated by transverse microradiography and fluoride in the biofilm was determined using an ion-selective electrode. Results were statistically analyzed by analysis of variance, at 5% of significance level. For groups C, SM, F, L, FL and LF, the means (standard-deviation) of mineral loss were 816.3 (552.5)(a), 3291.5 (1476.2)(c), 2508.5 (1240.5)(bc), 2916.2 (1323.7)(c), 1839.7 (815.2)(b) and 1955.0 (1001.4)(b), respectively; while lesion depths were 39.6 (22.8)(a), 103.1 (38.9)(c), 90.3 (44.6)(bc), 91.7 (27.0)(bc), 73.3 (26.6)(b), 75.1 (35.2)(b), respectively (different superscript letters indicate significant differences among groups). In conclusion, irradiation of root dentine with a pulsed CO2 laser at fluency of 12.0 J/cm(2) was able to inhibit root surface demineralization only when associated with fluoride. No synergy effect on the inhibition of root dentine mineral loss was provided by the combination of fluoride application and laser irradiation.20918381843Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CNPq [201746/2007-7

In situ mineral loss inhibition by CO2 laser and fluoride

Laser and fluoride treatments have been shown to inhibit enamel demineralization in the laboratory. However, the intra-oral effects of this association have not been tested. This study assessed in situ the effect of a Transversely Excited Atmospheric-pressure CO2 laser (lambda = 9.6 mu m) and the use of fluoridated dentifrice on enamel demineralization. During two 14-day phases, 17 volunteers wore palatal appliances containing human enamel slabs assigned to treatment groups, as follows: (1) non-fluoride dentifrice, (2) CO2 laser irradiation plus non-fluoride dentifrice, (3) fluoride dentifrice, and (4) CO2 laser irradiation plus fluoride dentifrice. A 20% sucrose solution was dripped onto the slabs 8 times per day. The specimens treated with laser and/or fluoridated dentifrice presented a significantly lower mineral loss when compared with those from the non-fluoride dentifrice group. The results suggested that CO2 laser treatment of enamel inhibits demineralization in the human mouth, being more effective when associated with fluoride.85761762

Combined effects of carbon dioxide laser and fluoride on demineralized primary enamel: An in vitro study

This in vitro study aimed at evaluating the efficacy of a CO2 laser (10.6 mu m) alone or combined with acidulated phosphate fluoride (APF) on the inhibition of lesion progression in primary enamel. The specimens were treated with/without CO2 laser and/or APF and submitted to pH cycling. Microhardness analysis was performed and the enamel mineral loss values were obtained. The groups treated with laser and/or APF presented lower mineral loss when compared to the control group (p < 0.05). Laser irradiation alone or combined with APF decreased lesion progression in primary enamel. However, the combined treatment did not show any significant additional effect. Copyright (c) 2007 S. Karger AG, Basel.411747

Physical and Compositional Changes on Demineralized Primary Enamel Induced by CO2 Laser

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Objective: This in vitro study aimed to evaluate the physical and chemical changes promoted by a CO2 laser at 10.6-mu m wavelength on primary dental enamel with artificial caries-like lesions. Background Data: Several previous investigations have shown that enamel can be modified by CO2 laser to obtain a caries-preventive effect, but the specific mechanism remains uncertain. Materials and Methods: Twenty-seven primary molars were randomly assigned to three groups as follows: control, carious, and laser (n = 9). The specimens from the carious and laser groups were demineralized and treated with or without CO2 laser, according to the group. Enamel surface changes after treatments were monitored using Fourier transform Raman spectroscopy and scanning electron microscopy (SEM). Results: The Raman spectra showed a statistically significant reduction of mineral content in carious and laser groups when compared to control group. Additionally, carbonate content was reduced in irradiated specimens when compared to the other groups. No physical change was observed in specimens evaluated by SEM. Conclusion: The results suggest that CO2 laser irradiation may reduce the carbonate content of enamel, which is likely to make this substrate more acid-resistant.o TEXTO COMPLETO DESTE ARTIGO, ESTARÁ DISPONÍVEL À PARTIR DE AGOSTO DE 2015.274585590Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [00=097028, 01=14384-8]CNPq [302393=2003-0

Photosensitization of in vitro biofilms by toluidine blue O combined with a light-emitting diode

In natural ecosystems, micro-organisms grow preferentially attached to surfaces, forming matrix-enclosed biofilms. The aim of this study was to determine photodestruction levels in biofilms after subjecting them to photodynamic therapy. Biofilms of Streptococcus mutans, S. sobrinus, and S. sanguinis were grown on enamel slabs for 3, 5 or 7 d. Both the number of viable micro-organisms and the concentration of water-insoluble polysaccharides were analysed, and mineral loss (Delta Z) analyses were performed on the enamel slabs. The antimicrobial potential of toluidine blue O (0.1 mg ml(-1)), associated with 85.7 J cm(-2) of a light-emission diode, was evaluated on the viability of 5-d biofilms. Both the number of micro-organisms and the concentration of water-insoluble polysaccharide increased with the age of the biofilms. A significant reduction (approximate to 95%) in viability was observed for S. mutans and S. sobrinus biofilms following photosensitization, with a > 99.9% reduction in the viability of S. sanguinis biofilms. In conclusion, a biofilm model was shown to be suitable for studying changes in bacterial numbers and enamel mineralization and for demonstrating the potential value of photosensitization in the control of in vitro biofilms.1141646

INFLUENCE OF ENVIRONMENTAL CONDITIONS ON PROPERTIES OF IONOMERIC AND RESIN SEALANT MATERIALS

Objectives: The aim of this study was to determine the effect of environmental conditions on the degradation of ionomeric and resin sealant materials. Material and Methods: FluroShield, Vitremer, and Ketac Molar disc-shaped specimens (n=18/material) were prepared, polished, subjected to initial hardness and roughness readings. Six discs of each material were randomly assigned to one of three different storage solutions: 0.3% citric acid (CA), demineralization solution (DE), and remineralization solution (RE). The specimens were individually immersed in 3 mL of the test solutions, which were daily changed. After 15 days of storage, new surface roughness and hardness readings were done. Fluoride release in the solutions was measured within 15 days. Data were analyzed by ANOVA and Tukey's and Contrast tests (alpha=0.05). Results: The storage in CA increased the roughness of Vitremer and Ketac Molar. A significant reduction in hardness was observed for all materials after storage in all solutions. For all materials, the greatest amounts of fluoride release occurred during the 1(st) day. FluroShield presented the same patterns of fluoride release in all solutions. Ketac Molar and Vitremer released the highest amounts of fluoride in the CA solution. Conclusions: Ionomeric materials are more susceptible to degradation than resin-based materials under acidic conditions. Acidic conditions lead to a higher fluoride release from ionomeric materials.17429430

Chemical, morphological and thermal effects of 10.6-mu um CO2 laser on the inhibition of enamel demineralization

Studies have shown that enamel can be modified by pulsed CO2 laser to form a more acid-resistant substrate. This study evaluated the effects of a 10.6-mu m CO2 laser on enamel surface morphology and chemical composition as well as monitored intrapulpal temperature changes during irradiation. Human teeth were irradiated with fluences of 1.5-11.5 J/cm(2), and pulpal thermal as well as chemical and morphological modifications on enamel were assessed. The teeth were submitted to a pH-cycling model, and the mineral loss was determined by means of cross-sectional microhardness. For all irradiated groups, intrapulpal temperature changes were below 3 degrees C. FT-Raman spectroscopy and scanning electron microscopy indicated that fluences as low as 6.0 J/cm(2) were sufficient to induce chemical and morphological changes in enamel. Then, for fluences reaching or exceeding 10.0 J/cm(2), laser-induced inhibitory effects on demineralization were observed. It was thus concluded that laser energy density in the range of 10.0 and 11.5 J/cm(2) could be applied to dental enamel in order to produce chemical and morphological changes and reduce the acid reactivity of enamel without compromising the pulp vitality.25345546

Relationships between occlusal or free-smooth and approximal caries in mixed dentition

This cross-sectional study aimed to examine the relationships between free-smooth or occlusal surfaces and approximal. caries in 104 schoolchildren between 6 and 8 years of age. Caries diagnosis was clinically and radiographically assessed, and white spot lesions, evident caries lesions or restorations, as well as radiolucence in enamel were considered to be caries. In the studied subjects, the correlations were analyzed in the 1st primary molars (Ds), the 2nd primary molars (Es), the 1st permanent molars (6s), and all molars. The data were statistically analyzed by chi-square test. Significant correlations between occlusal surface caries and approximal surface lesions were observed in Ds and Es teeth and in all molars, but not for 1st permanent molars. For free-smooth surface, these correlations were significant only for Es and all molars. Sensitivity and specificity for occlusal surface as an indicator of approximal caries in the same tooth type ranged from 73% to 83% and 51% to 58%, respectively. Similarly, for free-smooth surface the values varied from 22% to 60% and 57% to 90%, respectively. Sensitivity and specificity for occlusal surface caries in identifying subjects with approximal caries were 78% and 70%, respectively; for free-smooth surface, the corresponding values were 59% and 65%, respectively. The results suggest that visually detected caries lesions are indicative of approximal caries. Thus, if a certain risk limit is defined and the corresponding number of caries lesions in different surfaces is reached, the risk is above the threshold and could be a practical guideline on the need for radiography in this age group of patients with 'moderate caries experience'.63530831