Photodynamic therapy and photobiomodulation therapy in zoledronic acid-induced osteonecrosis in rats.

BACKGROUND: This study investigated the effect of antimicrobial photodynamic therapy (PDT), using methylene blue (MBO) and photobiomodulation therapy (PT), on the alveolar bone of rats submitted to bisphosphonate-induced osteonecrosis of the maxillaries (OMB) model using zoledronic acid (ZA). METHODS: Sixty rats divided into six groups were used: SALINE, PDT, ZA, ZA+PDT, ZA+PT, and ZA+MBO. Three weekly administrations (Days 0, 7, and 14) of ZA 0.20 mg/kg or saline solution were performed. After one month (Day 42), the exodontia of the left lower first molars were performed. An additional dose of ZA was administered at Day 49. PDT was performed on days 42, 45, 49, and 54. One month after exodontia (Day 70), the animals were euthanized to obtain samples for imaging and microscopic analysis. ANOVA/Bonferroni tests were used for statistical analysis. RESULTS: The ZA+PDT group showed a significantly lower percentage of apoptotic osteocytes than the ZA group (p < 0.001). The ZA+MBO, ZA+PT, and PDT groups significantly reduced the number of mononuclear cells compared to the ZA group (p < 0.001). The ZA+PT and ZA+PDT groups showed a significant reduction in the number of CD 68+ (p < 0.001) and CD3+ (p = 0.002) cells compared to the ZA group. The number of cells expressing INF-y had a significant reduction in the groups co-treated with PT and PDT compared to the ZA group (p < 0.001). CONCLUSIONS: We conclude that PDT and PT attenuated the severity of OMB and the inflammatory process due to a reduction of macrophages, T lymphocytes, and cytokines that stimulate the activity of these cells.

Toxicological and genotoxic evaluation of anacardic acid loaded-zein nanoparticles in mice.

Anacardic acid extracted from cashew nut shells of Anacardium occidentale L has demonstrated important biological activities, such as antibacterial activity against the cariogenic specie Streptococcus mutans. Zein nanoparticles containing anacardic acid (9.375 µg/mL) were evaluated in terms of toxicity and genotoxicity in vivo. The subacute toxicity assay was used to evaluate the cumulative effects of the oral administration of nanoencapsulated anacardic acid at 2.25 and 112.5 µg/kg for 7 days in mice, simulating a mouth rinse short-term clinical course treatment. Blank zein nanoparticles and saline solution 0.9 % were used as negative controls. Peripheral blood samples were collected to evaluate the genotoxicity in polychromatic erythrocytes using the micronucleus test. The animals were anesthetized, euthanized and the target organs collected, weighed and submitted to histopathological analysis. Liver, kidney and spleen relative weights did not change. Nevertheless, stomach, lung and heart increased the relative weights in the group receiving the highest dose, in which occasional histopathological findings were also identified. Both doses maintained the micronucleus frequency within the normal range and the animals treated with the highest dose presented a discrete weight lost, which could explain the organs' relative weight reductions. Blank and anacardic acid loaded zein nanoparticles were nontoxic when administered repeatedly for 7 days, as no relevant histopathological changes neither genotoxicity were observed. These preparations demonstrated limited toxicity under the conditions used in this study and could become an antibacterial alternative for preventing/treating oral infections in short-term treatments.

Antimicrobial effect of anacardic acid-loaded zein nanoparticles loaded on Streptococcus mutans biofilms.

Bacterial biofilms play a key role in the pathogenesis of major oral diseases. Nanoparticles open new paths for drug delivery in complex structures such as biofilms. This study evaluated the antimicrobial effect of zein nanoparticles containing anacardic acid (AA) extracted from cashew shells of Anacardium occidentale on in vitro Streptococcus mutans biofilm formation and mature biofilms. The minimum inhibitory concentration (MIC), minimum bacterial concentration (MBC), and antibiofilm assays were performed. Streptococcus mutans UA159 biofilms were formed on saliva-coated hydroxyapatite disk for 5 days. To evaluate the preventive effect on biofilm formation, before contact with the inoculum, the disks were immersed once for 2 min in (1) hydroethanolic solution; (2) blank zein nanoparticles; (3) zein nanoparticles containing AA; and (4) 0.12% chlorhexidine gluconate. To determine the effect against mature biofilms, the disks containing 5-day preformed biofilms were further treated using the same procedure. The bacterial viability and dry weight were determined for both assays and used to compare the groups using ANOVA followed by Tukey's test (p < 0.05). Both MIC and MBC for AA-loaded zein nanoparticles were 0.36 µg/mL. Groups 3 and 4 were very effective in inhibiting S. mutans biofilm formation, as no colony-forming units were detected. In contrast, for mature biofilms, no difference in bacterial viability (p = 0.28) or dry weight (p = 0.09) was found between the treatments. Therefore, the AA-based nanoformulation presented very high inhibitory and bactericidal activities against planktonic S. mutans, and the results indicate a strong antiplaque effect. However, the formulation showed no antimicrobial effect on the established biofilm.

Ação do laser infravermelho em suspensões de Streptococcus mutans / Infrared laser action on Streptococcus mutans suspensions

Introdução: os benefícios do laser infravermelho no tratamento da mucosite oral e no controle da dor na disfunção da articulação temporomandibular são bem reconhecidos e já aplicados clinicamente. Porém, o efeito dessa terapia em bactérias da cavidade oral ainda é incerto. Objetivo: analisar o efeito do laser infravermelho Diodo de Arseneto de Gálio Alumínio (AsGaAl) (LIV) nos níveis de suspensões de Streptococcus mutans UA159. Método: o laser de baixa potência infravermelho e comprimento de onda predominante de 880nm (Therapy XT-ESTM, DMC Equipamentos) foi utilizado com potência de 100mW e diâmetro da ponteira 0,0280 cm². A suspensão bacteriana foi ativada em estufa bacteriológica a 37ºC e 5% CO2, durante um período de 18 horas, ajustada para a concentração de 1-2 x 108 unidades formadoras de colônia/mL (UFC/mL). As suspensões foram submetidas aos seguintes protocolos experimentais e controle: grupo 1) LIV 30s; grupo 2) LIV 60s; grupo 3) LIV 90s; grupo 4) NaCl 0,9%. Em seguida, uma alíquota foi retirada para a diluição seriada e semeadura das amostras. As placas permaneceram em estufa bacteriológica a 37ºC e 5% CO2 durante um período de 48 horas para posterior contagem das UFC/mL. O estudo foi conduzido em triplicata. Resultados: os resultados, a seguir, estão expressos em Log UFC/mL: grupo 1 (8,42±0,16); grupo 2 (8,41±0,03); grupo 3 (8,37±0,11); grupo 4 (8,37±0,16). Não foi observada diferença estatisticamente entre os grupos (p>0,05). Conclusão: o estudo mostrou que o laser infravermelho, nas condições experimentais usadas, não demonstrou ação na viabilidade de S. mutans presentes em suspensões in vitro.

Introduction: The benefits of infrared laser in the treatment of oral mucositis and pain control in temporomandibular joint dysfunction are well recognized and applied clinically. However, the effect of this therapy on oral cavity bacteria is still uncertain. Objective: Analyze the effect of infrared laser Gallium Arsenide Diode (AsGaAl) (LIV) on the levels of Streptococcus mutans UA159 suspensions. Method: Low-power infrared laser with predominant wavelength of 880nm (Therapy XT-ESTM, DMC Equipment) was used with 100mW output power and tip diameter 0.0280cm².The bacterial suspension was activated in a bacteriological oven at 37 ° C and 5% CO 2 for a period of 18 h, adjusted to the concentration of 1-2 x 108 colony forming units / mL (CFU / mL).The suspensions were submitted to the following experimental protocols and control: Group 1)LIV 30s; group 2)LIV 60s; Group 3)LIV 90s; Group 4)saline solution. After that, an aliquot was taken for serial dilution and plating of the sample. The plates were kept in a bacteriological oven at 37°C and 5% CO2 for 48 hours for subsequent cfu/ml counts. The study was conducted in triplicates. Results: The following results are expressed in Log ufc/mL: Group 1 (8.42 ± 0.16); Group 2 (8.41 ± 0.03); Group 3 (8.37 ± 0.11); Group 4 (8.37 ± 0.16). There was no statistically significant difference between groups (p>0.05). Conclusion: In the experimental tested conditions, the study showed that the infrared laser had no action on the viability of S. mutans suspensions in vitro.