Fatima A. A. Zanin

Effects of low-level laser therapy on malignant cells: in vitro study.

The aim of this study was to assess the effect of 635- and 670-nm laser irradiation on H.Ep.2 cells in vitro using MTT. In addition to our previous report on the effects of LLLT on the proliferation of laryngeal carcinoma cells in which it was found that irradiaton H.Ep.2 cells with 670-nm laser results in increased cell proliferation, it was decided to evaluate the effect of increased doses of laser light on these cells. The cells, obtained from SCC of the larynx, were routinely processed from defrost to the experimental condition. The cultures were kept either at 5% or 10% of FBS. Twenty-four hours after transplantation, the cells were irradiated with laser light (5-mW diode lasers; 635 and 670-nm; beam cross section approximately 1 mm) at local light doses between 0.04 and 4.8.10(4) Jm(-2). For 670 nm, significant differences in the proliferation were observed between the two concentrations of FBS (p = 0.002) and between irradiated cultures and controls (p = 0.000). Although the results were not significant, 635-nm irradiated cells also proliferated more than nonirradiated ones. This occurred under both conditions of nutrition. It is concluded, that irradiation with 670-nm laser light applied at doses between 0.04 and 4.810(4) Jm(-2) could significantly increase proliferation of laryngeal cancer cells.

Use of 660-nm Diode Laser in the Prevention and Treatment of Human Oral Mucositis Induced by Radiotherapy and Chemotherapy

OBJECTIVE The aim of this multidisciplinary study was to evaluate quantitatively and qualitatively the effect of a 660-nm diode laser in the prevention and treatment of human oral mucositis (OM) in patients suffering from head and neck cancer who had undergone radiotherapy and chemotherapy. BACKGROUND DATA OM is a severe oral lesion resulting from the toxic effects of treatment for cancer in the head and neck region. Low-level laser therapy is indicated to prevent and treat this oral complication and may be used alone or in association with conventional drug treatment, producing pain relief and wound repair. METHODS This study included 72 patients with head and neck cancer treated at the Cancer Hospital of Mato-Grosso, Brazil, and divided into a control group (C; n = 36) and a laser group (L; n = 36). Laser therapy was performed in combination with radiotherapy and chemotherapy twice a week using a diode laser (lambda = 660 nm, power = 30 mW, spot size = 2 mm, energy = 2 J per point). RESULTS Statistically significant differences were observed between the two groups. Patients in group L usually did not present with OM or pain, but all patients in group C presented with OM ranging from Level I to III associated with pain. This difference was significant from week 1 on, increased until week 4 and remained stable up to week 7. CONCLUSION Laser therapy was effective in preventing and treating oral effects induced by radiotherapy and chemotherapy, thus improving the patients quality of life.

Evaluation of dentin root canal permeability after instrumentation and Er:YAG laser application

Smear layer removal with EDTA from root canal walls allows greater cleaning and disinfection of root canals. However, because Er:YAG laser acts on the removal of the smear layer, the objective of investigation was to analyze in vitro the effect of Er:YAG laser on dentin root canal wall permeability after endodontic instrumentation and irrigation with water or sodium hypochlorite and Er:YAG laser application.

Effects of Er:YAG laser irradiation and manipulation treatments on dentin components, part 2: energy-dispersive X-ray fluorescence spectrometry study

The effects of laser etching, decontamination, and storage treatments on dentin components were studied by energy-dispersive X-ray fluorescence spectrometry (EDXRF). Thirty bovine incisors were prepared to expose the dentin surface and then divided into two main groups based upon the decontamination process and storage procedure: autoclaved (group A, n=15) or stored in aqueous thymol solution (group B, n=15). The surfaces of the dentin slices were schematically divided into four areas, with each one corresponding to a treatment subgroup. The specimens were either etched with phosphoric acid (control subgroup) or irradiated with erbium-doped yttrium-aluminum-garnet (Er:YAG) laser (subgroups: I-80 mJ, II-120 mJ, and III-180 mJ). Samples were analyzed by micro-EDXRF, yielding three spectra for each area (before and after treatment). Surface mappings covering an area of 80x60 points with steps of 20 mum were also performed on selected specimens. The amount of Ca and P in group A specimens decreased significantly (P<0.05) after the acid etching and the CaP ratio increased (P<0.001). Er:YAG laser-etching using lower laser energies did not produce significant changes in dentin components. The mapping data support the hypothesis that acid etching on dentin produced a more chemically homogeneous surface and thus a more favorable surface for the diffusion of adhesive monomers.

Effects of Er:YAG laser irradiation and manipulation treatments on dentin components, part 1: Fourier transform-Raman study.

The effects of laser etching, decontamination, and storage treatments on dentin components were studied using Fourier transform (FT)-Raman spectroscopy. Thirty bovine incisors were prepared to expose the dentin surface and then divided in two main groups based upon the decontamination process and storage procedure: autoclaved (group A, n=15) or stored in thymol aqueous solution (group B, n=15). The surfaces of the dentin slices were schematically divided into four areas, with each one corresponding to a treatment subgroup. The specimens were either etched with phosphoric acid (control subgroup) or irradiated with erbium-doped yttrium-aluminum-garnet (Er:YAG) laser (subgroups: I-80 mJ, II-120 mJ, and III-180 mJ, and total energy of 12 J). Samples were analyzed by FT-Raman spectroscopy; we collected three spectra for each area (before and after treatment). The integrated areas of five Raman peaks were calculated to yield average spectra. The areas of the peaks associated with phosphate content (P<0.001), type I collagen, and organic C-H bonds (P<0.05) were reduced significantly in group A (control). Analyses of samples irradiated with reduced laser energies did not show significant changes in the dentin components. These results suggest that thymol storage treatment is advised for in vitro study; furthermore, 12 J of Er:YAG laser energy does not affect dentin components.

Raman Spectroscopy Validation of DIAGNOdent-Assisted Fluorescence Readings on Tibial Fractures Treated with Laser Phototherapy, BMPs, Guided Bone Regeneration, and Miniplates

OBJECTIVES We aimed to assess through Raman spectroscopy and fluorescence the levels of calcium hydroxyapatite (CHA) and lipids and proteins in complete fractures treated with internal rigid fixation (IRF) treated or not with laser phototherapy (LPT) and associated or not with bone morphogenetic proteins (BMPs) and guided bone regeneration (GBR). BACKGROUND Fractures have different etiologies and treatments and may be associated with bone losses. LPT has been shown to improve bone healing. METHODS Tibial fractures were created on 15 animals and divided into five groups. LPT started immediately after surgery, repeated at 48-h intervals. Animal death occurred after 30 days. RESULTS Raman spectroscopy and fluorescence were performed at the surface. Fluorescence data of group IRF + LPT + Biomaterial showed similar readings to those of the group IRF-no bone loss. Significant differences were seen between groups IRF + LPT + Biomaterial and IRF + LPT; IRF + LPT + Biomaterial; and IRF + Biomaterial; and between IRF + LPT + Biomaterial and IRF. CH groups of lipids and proteins readings showed decreased levels of organic components in subjects treated with the association of LPT, biomaterial, and GBR. Pearson correlation showed that fluorescence readings of both CHA and CH groups of lipids and proteins correlated negatively with the Raman data. CONCLUSIONS The use of both methods indicates that the use of the biomaterials associated with infrared LPT resulted in a more-advanced and higher quality of bone repair in fractures treated with miniplates and that the DIAGNOdent may be used to perform optical biopsy on bone.

Comparison of the effects of the CO2 laser and chlorohexidine on the decontamination of infected cutaneous wounds: a histologic study in rats.

OBJECTIVE The aim of this study was to compare histologically the effects of CO2 laser and chlorohexidine gluconate (4%) on Staphylococcus aureus-infected cutaneous wounds. BACKGROUND DATA Wound infection constitutes a big risk for patients, and it is usually associated with increased morbidity, mortality and hospital costs. It is accepted that local treatment of these infections is effective. MATERIALS AND METHODS Standardized wounds created on the dorsum of 36 rats were infected with Staphylococcus aureus and treated during 6 days as follows: group I, chlorohexidine gluconate (4%) applied to the wound surface during 1 min during 6 days; group II, single CO2 laser irradiation (8 W, CW, unfocused, 8-cm focal distance, 81,530 W/cm(2)), maintaining surface debris; group III, single CO2 laser irradiation (8 W, CW, unfocused, 8-cm focal distance, 81,530 W/cm(2)), removing the surface debris. Seven days after wounding, the animals were killed and specimens taken for light microscopy. RESULTS On control wounds, epithelial ulceration and neutrophylic and lymphoplasmocitary inflammatory infiltrate was observed. On group II, there was epithelial hyperplasia, areas of ulceration and intense neutrophylic and lymphoplasmocitary inflammatory infiltrate. In group III, there was a neutrophylic inflammatory infiltrate underneath the surface debris and below that intense lymphoplasmocitary inflammatory infiltrate. When the surface debris was removed (group IV), there was epithelial ulceration and mild lymphoplasmocitary inflammatory infiltrate and fibroblasts and collagen fibers. CONCLUSION The results of this study show that infected wounds treated with 4% chlorohexidine show a more pronounced inflammatory reaction when compared to that observed when the CO2 laser is used, especially when surface debris are removed; surface debris removal on laser-treated wounds results in better and more rapid healing; the surface debris may act as a culture medium for bacterial growth or, because of its characteristics, it may act as a local irritant and delay healing.

Effect of energy (J) on temperature changes at apical root surface when using Er:YAG laser to enlarge root canals

The use of lasers for cleaning, shaping and disinfecting root canals must not produce heat which damages periapical tissue and alveolar bone. The aim of the present study was to determine the increase of external temperature at the apical surface of the root canal after Er:YAG laser irradiation with a 250 micrometer diameter fiberoptic guide with and without distilled and deionized water at 3 different total energies. Thirty single-rooted teeth were instrumented to #25 K-file using distilled and deionized water for irrigation. They were divided into three groups according to total energy (15J, 30J and 45J with 15 Hz and 140 mJ per pulse). Each group was irradiated with water and then without water. The increase in temperature at the apical root surface was measured with a multimeter and a thermocouple. Changes in apical temperature were significantly different in all groups (p less than 0.01; 15 J less than 45 J less than 30 J). Less time was necessary for return to initial room temperature at 15 J. We conclude that in vitro use of the Er:YAG laser (total energy of 15, 30, and 45 J) increased external apical root temperature and that the root canal must be filled with distilled and deionized water to reduce the risk of an increase in temperature.

LLLT in treating dentinary hypersensibility: a histologic study and clinical application

Dental hypersensitivity has been studied for several years and it is reported as a striking painful condition that originates from the exposition of dentinal tubuli as a result of the reduction of the thickness of the enamel or cement. Usually the exposed area is subjected to several kinds of stimuli, resulting in a rapid sharp acute pain. The aim of this study was evaluated the efficiency of LLLT in the treatment of patients with dental hypersensitivity. 1102 teeth of 388 patients from the Laser Center of the Camilo Castelo Branco University were treated with LLLT between 1995-2000. 98 males and 290 females aged 30 to 45 years old were treated. For LLLT, a diode laser was used at 780nm, CW, 40mW, elliptical area of the beam 2mm2, exposure time per point 25s. This corresponds to an equivalent dose of 50 J/cm2 at each point (considering the area of the spot). If a 1cm2 area is considered, the total dose per tooth is 4J/cm2. With the diode laser 830nm, CW, 50mW, elliptical area of the beam 2mm2, exposure time per po int of 20s. This corresponds to an equivalent dose of 50J/cm2 at each point (considering the area of the spot). If a 1cm2 area is considered, the total dose per tooth is 4J/cm2. The results showed 403 (36.57%) out of 1102 teeth required a single session for complete remission of the symptoms. 255 (23.14%) needed two sessions; 182 (16.51%) three sessions; 107 (9.7%) four sessions; and 59 (5.35%) five sessions. 96 (8.71%) did not respond to LLLT and the patients were re-assessed and treatment changed. The more affected tooth was the lower premolar (301 - 27.4%), followed by lower molars (163 - 14.8%), upper premolar (149 - 13.5%), and upper molars (52 - 4.7%), upper canine (119 - 10.7%), upper incisive (108 - 9.9%), lower canine (62 - 5.6%), and upper molars (52 - 4.7%). The result of the present investigation demonstrates indeed that LLLT, when based on the use of correct irradiation parameters, is effective in treating dentinal hypersensitivity as it quickly reduces pain and maintains a prolonged painless status. The authors concluded that the use of LLLT was effective on 91.27% of the cases. Previous studies were carried out by the authors to evaluate histologically the reaction of the dentinal pulp in rats after application of LLLT. The LLLT was shown to be efficient in the stimulation of odontoblast cells, producing reparative dentin and closing dentin tubuli.

Use of laser fluorescence in dental caries diagnosis: a fluorescence x biomolecular vibrational spectroscopic comparative study

The aim of this work was to verify the existence of correlation between Raman spectroscopy readings of phosphate apatite (~960 cm-1), fluoridated apatite (~575 cm-1) and organic matrix (~1450 cm-1) levels and Diagnodent® readings at different stages of dental caries in extracted human teeth. The mean peak value of fluorescence in the carious area was recorded and teeth were divided in enamel caries, dentin caries and sound dental structure. After fluorescence readings, Raman spectroscopy was carried out on the same sites. The results showed significant difference (ANOVA, p<0.05) between the fluorescence readings for enamel (16.4 ± 2.3) and dentin (57.6 ± 23.7) on carious teeth. Raman peaks of enamel and dentin revealed that ~575 and ~960 cm-1 peaks were more intense in enamel caries. There was significant negative correlation (p<0.05) between the ~575 and ~960 cm-1 peaks and dentin caries. It may be concluded that the higher the fluorescence detected by Diagnodent the lower the peaks of phosphate apatite and fluoridated apatite. As the early diagnosis of caries is directly related to the identification of changes in the inorganic tooth components, Raman spectroscopy was more sensitive to variations of these components than Diagnodent.