Effects of an erbium, chromium: yttrium, scandium, gallium, garnet laser on mucocutanous soft tissues.

OBJECTIVES: Lasers are effective tools for soft tissue surgery. The erbium, chromium: yttrium, scandium, gallium, garnet laser is a new system that incorporates an air-water spray. This study evaluates the cutting margins of this laser and compares healing with laser and conventional scalpel and punch biopsy-induced wounds. STUDY DESIGN: New Zealand white rabbits were divided into serial sacrifice groups; the tissues were grossly and microscopically analyzed after laser and convential steel surgical wounding. RESULTS: Wound margins were found to show minimal edge coagulation artifact and were 20 to 40 mm in width. Laser wounds showed minimal to no hemorrhage and re-epithelialization and collagenization were found to occur by day 7 in both laser and conventional groups. CONCLUSIONS: The new laser system is an effective soft tissue surgical device; wound healing is comparable to that associated with surgical steel wounds. The minimal edge artifact observed with this laser system should allow for the procurement of diagnostic biopsy specimens.

Preliminary investigations on the utility of an erbium, chromium YSGG laser.

A variety of laser systems are under investigation as potential tools in dentistry. Most of these systems have been shown to be efficacious for soft tissue surgery of the mucous membranes; however, cutting bone and dental hard tissues has only recently been possible. In this report from the University of California at Los Angeles School of Dentistry, a review of laser applications in dentistry is discussed. The utility of a new laser system using an erbium YSGG medium with air water spray to cut soft tissues, bone, enamel and dentin is under investigation and preliminary research findings are presented.

Effects of Nd:YAG laser on the permeability of root canal wall dentin.

The effects of a thermally cooled pulsed Nd:YAG laser on the permeability and structural appearance of the root canal wall were investigated in vitro. Twenty specimens of freshly extracted human teeth were prepared by conventional methods. The teeth were randomly divided into two groups. Group 1 teeth were prepared conventionally but not lased. Group 2 specimens received three 15-s laser exposures totaling 45 s duration within the root canal via optical fiber delivery. Laser parameters were set at 5 W, 50 Hz, using a simultaneous air/water coolant spray of 10 psi air and 2 psi water. The external surfaces of the teeth were sealed with acrylic and placed in 2% methylene blue dye for 24 h. The teeth were then sectioned, photographed, and compared under light microscope for the extent of dye penetration. The specimens were subsequently prepared for scanning electron microscopy for correlation of permeability measurements with surface modifications. The combined use of scanning electron microscopy and dye permeability measurements revealed a sealing of the dentinal wall by deposition of glass-like material and, in one specimen, the bridging of a lateral canal that partially occluded the canal. Based on statistical comparisons, permeability of laser-treated teeth was significantly less than untreated specimens (alpha = 0.005).

Histologic effects of a thermally cooled Nd: YAG laser on the dental pulp and supporting structures of rabbit teeth.

The histologic response of the pulp, periapical tissues, supporting periodontal ligament, and alveolar bone adjacent to the incisor teeth of adult rabbits was compared after laser treatment (etching) or drilling with a high-speed dental rotary handpiece (enamelplasty) on the buccal enamel surface. Observations were made at four time periods, 2 days, 14 days, 60 days, and 180 days after treatment. Block sections were removed, and serial sections were prepared and examined by an independent veterinary pathologist for occurrences of histopathologic changes with untreated control teeth used for comparison. Under the conditions of this study, there were no differences between either the laser-treated or the drilled specimens compared with the untreated control teeth on the basis of the histologic appearance.

The efficiency of bone ablation with an Nd:YAG laser beam delivered with a cooling spray: an in vitro study.

This investigation studied the ablation of cortical bone with a neodymium:yttrium-aluminium-garnet (Nd:YAG) laser and how an air and water cooling spray effectively reduced the amount of heat transferred to the surrounding tissue. A 600-microns-diameter optical fiber and a 400-microns-diameter optical fiber were used to deliver an Nd:YAG laser beam to the cortical bone of two rabbit tibiae while a continuous air and water cooling spray provided cooling and irrigation to the tissue site. Different power settings and energy densities were used on 6 groups of 10 holes each. The holes were then prepared for scanning electron microscope examination and average and standard deviations were calculated for each group of collected data. The results showed that the Nd:YAG pulsed laser beam with an experimental cooling irrigation system ablated bone efficiently with minimal thermal damage.

A comparison of dentin permeability after bur and laser apicoectomies.

This investigation compared the permeability of dentinal tubules after laser beam and conventional bur apicoectomies. Twenty roots were rountinely instrumented and obturated with laterally condensed gutta-percha. A bur was used to cut the apexes of 10 teeth, while the remaining 10 were cut with a laser beam carried through an optic fiber. A 35-W pulsed Nd:YAG laser system capable of cooling the irradiated area with an air and water spray supplied the power. Except for the apex, the teeth surfaces were coated with a blue wax. The samples were stored for 36 hours in a 2.5% methylene blue solution and were washed, split, and measured for dye penetration. Linear penetration in series 1 averaged 2.4 mm, while series 2 measured 0.9 mm. The laser apicoectomy appears to reduce the permeability of dentinal tubules.