Photobiomodulation,Photomedicine,and Laser Surgery

Objective: The goal of this study is to determine the optical properties of different rat tissues with respect to spatial intensity variation and light distribution. We are interested mainly in the wavelength of 630 nm. Nevertheless, for liver tissue we have used 514 nm and 670 nm as well. Background Data: In the past, many articles have been written about the interaction of lasers with rat tissues. However, the technique of imaging the light distribution allows us to obtain the spatial scattering as well as an effective attenuation coefficient for the light intensity. Methods: Slices of different rat tissues were placed between two microscope slide mounts (spaced by 3 mm). A laser beam was irradiated on the sandwiched tissue. A CCD camera placed on the side, orthogonal to the beam path, recorded the intensity distribution of the scattered light. Analysis of this spatial intensity profile allowed determining the variation of the intensity as the light penetrates the tissue. Results: We have found that abdominal wall fat presents the lowest exponential decay when compared with liver, muscle, and kidney. The obtained values provided good data about the light distribution in those tissues when irradiated with a nondiffuse laser beam. For all tissues, we observed a spherical light distribution and exponential decay. Cirrhotic liver shows much stronger decay than healthy liver. These results are useful for several applications of laser for biostimulation a phototherapy.

Objective: To evaluate application of laser biostimulation in the treatment of antro-oral communications. Background Data: Sixty-one patients between the ages of 14 and 58 were subjected to biostimulation with laser light. Therapy was performed with a CTL 1106 biostimulative laser of 30 mW power with a tip-emitting light of 830-nm wavelength. Methods: Three cycles of laser irradiation were performed in a continuous mode. During one cycle, 3.5 min of extraoral irradiation of 4J with the contact "sweeping" method or the "woodpecker technique" was made through the facial skin to the suborbital region, 3.5 min of intraoral irradiation of 4J with the contact "point" method to the region of maxillary sinus floor, and 3.5 min of intraoral one of 4J with the contact "point" method to the alveolar process at the site of the antro-oral communication. The above cycle of irradiation was repeated for 4 days. Results: After 4 days of laser therapy, a complete closure of antro-oral communication occurred. Conclusion: Laser therapy can be recommended as an effective method of treatment in this type of complication following tooth extraction.

Objective: To use the CO₂ laser-assisted tympanic membrane fenestration in office settings, under local anesthesia, as the sole treatment for patients with chronic otitis media with effusion(OME). Background Data: This new treatment ensures artificial ventilation of the middle ear for several weeks, and provides an intermediate solution between ordinary lancet-made tympanocentesis and transtympanic ventilation tube insertion. The operative technique is already well codified, and preliminary studies have demonstrated that tympanic membrane fenestration does not expose patients to any major hazard. Methods: We treated 30 ears in 21 children and 29 ears in 24 adults. All patients had presented with OME persistent for more than 3 months. The laser tympanostomy was performed under local anesthesia, as an outpatient procedure, using a CO₂ flash-scanning laser in conjunction with a handpiece (OTOLAM™). Using a power of 12 W to 17 W, a single laser pulse usually sufficed to create a 2-mm-diameter circular perforation in the anteroinferior quadrant of the eardrum. Results: The tympanic membrane fenestration allows avoiding ventilation tube insertion in 63% of children and 75% of adults. Conclusions: The CO₂ laser-assisted tympanic membrane fenestration seems a valid therapeutic option addressing OME. This study should be pursued on a larger scale to define more precisely the indications of the laser tympanostomy.

Objective: In this case report, the treatment of a buccal lymphangioma in a 9-year-old female was done using the Nd:YAG laser and the clinical outcome was evaluated. Background Data: The treatment of lymphangioma with the laser surgery using Nd:YAG and CO₂ laser has become favorable due of a lack of postoperative pain and hemorrhage. Methods: The lesion was treated with a pulsed Nd:YAG laser (d-lase 300, American Dental Laser, Detroit, MI). An exposure of 10 min each was performed at an interval of 10 days by the noncontact method with the energy density of 1 W, 10 Hz. Results: It was observed that there was a great reduction of the lesion and a considerable reduction of the external facial volume. As the excision of the lesion was avoided in our present study, there was no pain and hemorrhage. A remarkable reduction of the tumor size could be observed visually within the five laser exposures. Conclusions: It can be concluded that if Nd:YAG laser therapy is used for reducing the tumor size as a primary treatment, the operation becomes easy and the recurrence may be less than with the conventional treatment, and an option of a surgical or laser excision could be reserved.

Objectives: In an attempt to increase the successful rate of endodontic surgical procedures this study proposes the use of an association of three lasers in apicectomy: Er:YAG laser, (wavelength 2.94 μm pulse mode), Nd:YAG laser (wavelength 1.064 μm, pulse mode), and Ga-Al-As laser, (wavelength of 790 nm, continuous wave). Background Data: Previous studies have shown the low success rate of apicectomy by conventional methods due to the presence of remaining bacteria in the surgical site. Methods: The Er:YAG laser was used to perform osteotomy and root resection without vibration, discomfort, less contamination of the surgical site, and no smear-layer on the dentine surface. The Nd:YAG laser irradiation through a fiber performed sealing of the dentinal tubules and bacterial reduction of the cavity bone. In addition, the improvement of healing and better post-operative achieved with the Ga-Al-As laser encourages the use of those lasers in periapical surgeries.Results: Three years follow-up examination of the clinical case showed radiographically significant decrease of the radiolucent periapical area and no clinical signs and symptoms. Conclusion: The outcome of this clinical case indicates that the use of those lasers could be considered an alternative, suitable, and useful method to perform an apicectomy.

Objectives: The purpose of this study was to evaluate, in vitro, the tensile bond strength of the Single Bond (3M) adhesive system placed over dentin surfaces treated with air turbine, Er:YAG laser without contact and in focused or air abrasion. Summary Background Data: The use of dentin adhesives is a well-established clinical routine among the dentists. However, there have been few reports comparing the influence of the Er:YAG laser, air abrasion, and air turbine on the Single Bond tensile bond strength of adhesives systems to dentin fact that could influence which tools dentists select for use in cavity preparations. Methods: Twenty-three extracted retained human molars were used in this study. The coronal portion was divided in two parts and fixed in acrylic resin; the occlusal surface was abraded to a 2-mm width with a mechanic lathe until the dentin surface was completely exposed. The dental portions were divided into three groups of 15 each and treated with Er:YAG laser, air abrasion, or air turbine. A 3 mm hole in the center of each tooth was marked off using contact paper. Single Bond (3M) adhesive system was applied after acid phosphoric at 35% application for 15 sec over dentin surfaces. A resin composite cone was built into the delimited area to accomplish the tensile bond strength test on the EMIC universal test machine. The specimens were then evaluated by stereoscopy to determine the type of failures into the dentin-adhesive-resin composite surface. Results: The tensile test was performed using the universal testing machine EMIC DL-2000 at a cross-head speed of 0.5 mm/min. The average results were: air turbine (17.52 MPa), Er:YAG laser (16.65 MPa) and air abrasion (15.83 MPa). Statistical treatment by ANOVA and Tukey's test (p < 0.01) showed no significant differences between the groups tested. The tensile bond strength test to the dentin showed no significant difference among the three groups when the Single Bond was used after the 35% phosphoric-acid conditioning. The stereoscopy showed a predominant adhesive failure in all groups. Conclusion: These results suggest that Single Bond tensile bond strength is the same as dentin prepared by Er:YAG laser, air abrasion, or air turbine.