José Luiz Lage-Marques

High-power diode laser in the disinfection in depth of the root canal dentin

OBJECTIVE The objective of this study was to evaluate the disinfection degree of dentine caused by the use of diode laser after biomechanical procedures. STUDY DESIGN Thirty teeth were sectioned and roots were autoclaved and incubated for 4 weeks with a suspension of Enterococcus faecalis. The specimens were randomly divided into 3 groups (n = 10): G1, instrumented with rotary files, irrigated with 0.5% sodium hypochlorite and 17% EDTA-T, and then irradiated by 830-nm diode laser at 3 W; G2, the same procedures as G1 but without laser irradiation; and G3, irrigation with saline solution (control). Dentin samples of each third were collected with carbide burs and aliquots were sowed to count viable cells. RESULTS The disinfection degree achieved was 100% in G1 and 98.39% in G2, when compared to the control group (G3). CONCLUSION Diode laser irradiation provided increased disinfection of the deep radicular dentin in the parameters and samples tested.

Effectiveness of Photodynamic Therapy Against Enterococcus faecalis, With and Without the Use of an Intracanal Optical Fiber: An In Vitro Study

BACKGROUND AND OBJECTIVE Photodynamic therapy (PDT) is a new technique introduced in endodontics that combines the action of a photosensitizer (dye) and a low intensity light source. Currently, there are no PDT studies evaluating the microbial disinfection of root canals in order to compare the effects of light delivery systems in the photosensitizer activation. The aim of this study was to evaluate the PDT effectiveness in reducing Enterococcus faecalis, with and without the aid of an intracanal optical fiber. METHODS Extracted single-rooted teeth were selected, instrumented, inoculated with E. faecalis and divided into six groups: one control group (untreated), one conventionally-treated group (1% NaOCl irrigation) and four PDT-treated groups. Irradiation (diode laser) was performed with (OF) or without an intracanal optical fiber (NOF) using two different irradiation times: 1 min and 30 sec (IT(90)) or 3 min (IT(180)). Samples were collected before and after testing procedures and CFU/mL was determined. RESULTS The greatest reduction of E. faecalis (99.99%) was achieved with irrigation with 1% NaOCl. PDT also significantly reduced E. faecalis in the following decreasing order: OF/IT(180), NOF/IT(180), OF/IT(90) and NOF/IT(90), with no significant statistical difference among the groups. CONCLUSIONS These results suggest that PDT was effective against E. faecalis, regardless of the use of an intracanal optical fiber.

Sealer penetration and marginal permeability after apicoectomy varying retrocavity preparation and retrofilling material

Apicoectomy failure is generally related to inappropriate marginal sealing of the retrocavity, which allows percolation of microorganisms and their products from root canal system to periapex. This study evaluated tubular penetration of canal sealers and marginal permeability after retrocavity irradiation with Er;Cr:YSGG laser and retrofilling with MTA or cyanoacrylate. Twenty-two single-rooted teeth were decoronated and endodontically treated, their apical 3 mm were resected and the root ends were retroprepared with a low-speed bur. Twenty roots were randomly assigned to 4 groups (n=5): GI and GII--retrofilling with MTA and cyanoacrylate, respectively; GIII and GIV--retrocavity irradiation with Er;Cr:YSGG laser (2.78 microm, 4 W, 20 Hz, 70.8 J/cm(2)) and retrofilling with MTA and cyanoacrylate, respectively. The remaining 2 roots served as positive and negative controls. The analysis of rhodamine B dye infiltration (p=0.05) demonstrated that laser irradiation and MTA retrofilling presented significantly higher permeability rates (p<0.05). Retrofilling with cyanoacrylate showed significantly lower permeability, either when laser was used or not on retrocavity. SEM analysis depicted more cyanoacrylate penetration through dentinal tubules when compared to MTA, suggesting a more efficient marginal sealing. Based on these results, it may be concluded that cyanoacrylate provided a less permeable retrofilling regardless of the retropreparation method, suggesting a more favorable condition to the establishment of the periapical healing.

Er: Yag laser irradiation of the microbiological apical biofilm

One problem in cases of healing-resistant periapical lesions is to eradicate the contamination at the periapical area. This contamination is due to the microbiological biofilm formed by microorganisms and their subproducts lodged in apical third of the root, on both cementum and dentin surface. Paraendodontic surgery consists of the mechanical removal of harmful agents to promote healing and periapical health. The purpose of this study was to assess the results of Er:YAG laser irradiation on the apical root third of newly extracted teeth to eliminate microbial contamination on root apex surface. Apical irradiation was performed with an Er:YAG laser device using an experimental contact tip, at 100 mJ, 10 Hz, 1 W, 39 J/cm(2), 3 times on the target area. SEM analysis showed the elimination of part of the irradiated cementum and the formation of small roughened without exposing the subjacent dentin. Vaporization of the remaining periodontal tissue and removal of microbiological apical biofilm (MAB) were also observed on the irradiated areas. Under the tested conditions and based on the findings of this study, Er:YAG laser may be considered effective for removal of microbiological apical biofilm.

Low- and High-Intensity Lasers in the Treatment of Herpes Simplex Virus 1 Infection

Herpes simplex virus (HSV) is one of the most common viral infections of the human being. Although most of the seropositive persons do not manifest symptoms, infected individuals may present recurrent infections, characterized by cold sores. HSV-1 infection can result in potentially harmful complications in some patients, especially in those with compromised immunity. We report a clinical case of a patient with severe oral HSV-1 infection in the lower lip. The treatment of the lesions with the association of high-intensity (erbium-doped yttrium aluminum garnet, 2.94 mum, 80 mJ/pulse, 2-4 Hz) and low-intensity (indium gallium aluminum phosphide, 660 nm, 3.8 J/cm(2), 10 mW) lasers has not been reported in the literature. During treatment, no systemic or topical medication was used. Pain sensitivity was completely gone after the first irradiation with the low-intensity laser. During the healing process, lesions were traumatized twice, on the days 4 and 7. Even though the lesions were completely healed within 10 days.

Time- and concentration-dependent cytotoxicity of antibiotics used in endodontic therapy

Objective New drugs have to be assessed in endodontic therapy due to the presence of microorganisms resistant to therapeutic procedures. Thus, this study evaluated the time- and concentration-dependent cytotoxicity of different antibiotics used in endodontic therapy. Material and Methods Human gingival fibroblasts were treated and divided into the following experimental groups: Group I - control; Group II - ciprofloxacin hydrochloride; Group III - clyndamicin hydrochloride; and Group IV - metronidazole. Each drug was used at concentrations of 5, 50, 150, and 300 mg/L for 24, 48, 72, and 96 h. Cytotoxicity was evaluated by the MTT assay [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] and spectrophotometric reading of ELISA plates. The results were analyzed by BioEstat 4.0 software using Kruskal-Wallis and Dunn’s tests at a significance level of 5%. Cell viability was assessed for the different concentrations and times. RESULTS All drugs presented dose-dependent cytotoxicity. Concentrations of 5 and 50 mg/L produced viable fibroblasts at all experimental times in all groups. Conclusions Cell viability at 24 h was greater than in the other experimental times. Comparison between the same concentrations of antibiotics at different times showed that metronidazole presented the highest cell viability at 72 and 96 h compared to the other antibiotics, whereas clyndamicin hydrochloride showed higher cell viability at 72 h than ciprofloxacin hydrochloride.

Surface finishing of unused rotary endodontic instruments: a SEM study

During endodontic therapy, cleaning of root canals is performed using endodontic files and auxiliary chemical substances, and it is important that the endodontist be familiar with the instruments used in daily practice. This study evaluated, under scanning electron microscopy (SEM), the quality of the surface finishing of unused rotary endodontic instruments. Fifty sizes 20, 25 and 30 rotary files from different commercial brands (ProFile, Protaper, Race, Hero and K3 Endo) were removed directly from their packages and had their final 3 mm examined with a scanning electron microscope at x190 magnification with no previous preparation. The images were evaluated by 3 skillful, calibrated, blinded observers according to the following criteria: cutting edge, debris, grooves, microcavities, tip shape, tip position, scraping and transition angle. Data were recorded in worksheets designed for the study. Irregular edges were observed in 50-100% of the files. Except for ProFile, all commercial brands presented surface debris in 100% of samples. Only Race files showed no grooves or microcavities. K3 Endo files presented the best tip centralization. Excetp for ProTaper files, all commercial brands presented blunt-cutting edges in 100% of samples. All types of files presented surface scraping. K3 Endo files and Protaper had a high percentage of transition angle. Based on the evaluation criteria used in the present study, most samples presented a minimum of 2 alterations and a maximum of 7 alterations per instrument. Under the tested conditions, the quality of the surface finishing of the examined instruments was not as expected, given that no instrument was free of imperfections and most of them presented at least 2 and up to 7 types of surface defects. These results suggest that the manufacturing process and the packaging conditions of rotary endodontic instruments are far from ideal.

Análise espectrofotométrica e visual do clareamento dental interno utilizando laser e calor como fonte catalisadora

This experiment aimed at evaluating, in vitro, the chromatic alteration of dental crowns submitted to internal bleaching. Color alterations were evaluated by means of spectrophotometric analysis and visual observation, at the following experimental phases: initial reading (LI), after-darkening reading (LE), immediate after-bleaching reading (LC), bleaching checked after 15 days (LC15) and after 30 days (LC30). After finding the values of L* (luminosity), a* and b* (shade and saturation), which made it possible to quantify the chromatic alterations of the specimens, color differences (deltaE ) were assessed by means of the CIE Lab Program. The statistical analysis of the results did not reveal any significant difference between conventional bleaching and bleaching activated by Er:YAG laser. No statistical difference was observed between the results after 15 and 30 days, for both experimental groups.

Effect of Chemical Substances in Removing Methylene Blue After Photodynamic Therapy in Root Canal Treatment

BACKGROUND AND OBJECTIVE The disadvantage of photodynamic therapy (PDT) is in the photosensitizing agents that may stain the tooth structure. There is no register of PDT studies evaluating protocols to minimize that concern. The present study evaluated the efficiency of chemical adjuncts in methylene blue dye (MB) removal after PDT. MATERIALS AND METHODS Forty single-rooted teeth, after root canal preparation, were filled with 0.01% MB for 5  min, and irradiated with diode laser 660  nm at 40  mW for 240  sec (total energy 9.6  J). The specimens were divided into four groups (n = 10), according to the chemical adjuncts used for dye removal: (a) 2.5% sodium hypochlorite (NaOCl); (b) 2.5% NaOCl + Endo-PTC cream; (c) 70% ethyl alcohol and (d) saline (control). The crowns were sectioned and fixed in a device. Photographs were taken before the PDT (T0), immediately after (T1) and upon dye removal (T2). The chromatic alterations were evaluated using Adobe Photoshop and K values were determined in four fixed points of each crown. RESULTS K values (dental staining) increased in all groups when comparing T0 and T1. The effectiveness of the tested adjuncts was, in decreasing order: G1 (-3.11) > G2 (-2.97) > G3 (-1.28) > G4 (-1.19), not observing significant statistical differences (p < 0.05) between G1 and G2 and also between G3 and G4. CONCLUSIONS Protocols to remove photosensitizing dyes should be applied after PDT in order to minimize dental stain. The protocols tested in this study by using 2.5% NaOCl, associated or not with Endo-PTC cream, were effective in avoiding tooth staining caused by MB during PDT.

In vitro evaluation of the effects of the interaction between irrigating solutions, intracanal medication and Er:YAG laser in dentin permeability of the endodontic system

The purpose of this study was to evaluate in vitro the effects of different associations between irrigating solutions (EDTA-T and citric acid), intracanal medicament (NDP), and Er:YAG laser irradiation on dentin permeability. Fifty-one extracted single-rooted teeth were instrumented and divided into seven groups. Groups GI and GII had final irrigation with a demineralizing solution only (EDTA-T and citric acid, respectively). Groups GIII and GIV had final irrigation with EDTA-T and citric acid, respectively, plus an association of irrigating solution and Er:YAG laser. Groups GV and GVI had final irrigation with EDTA-T and citric acid, respectively, plus an association of intracanal medication and Er:YAG laser. Group GVII (control group) had final irrigation with distilled water. All root canals were filled with NDP associated with rhodamine B dye. After the experimental period, the samples were transversely cut into six 2.0 mm thick slices for subsequent reading using the ImageLab software. Analysis of the results allowed us to conclude that there were statistically significant differences (p < 0.05) between the groups as to the penetration of the dye-intracanal medication solution. Groups III and IV presented smaller values of dentinal permeability when compared to the other groups. The best results were obtained with the interaction between a demineralizing irrigating solution and the association of intracanal medicament and laser Er:YAG (groups V and VI). In these groups the observed penetration of the intracanal medicament plus dye solution in the apical third was, on average, 29% greater than in the other groups.