Removal of carious dentin by Er:YAG laser irradiation with and without carisolv

OBJECTIVE: The purpose of this study was to investigate the effectiveness of caries removal by using an Er:YAG laser irradiation with and without Carisolv, in vitro. BACKGROUND DATA: Effective ablation of dental hard tissues using Er:YAG laser has been reported and its application to caries removal has been expected. METHODS: Five extracted human teeth were selected for Carisolv and burr treatment. One-half of the lesion was treated with the Carisolv and then removed. The other half was removed using burr treatment. Fifty teeth were subjected to Er:YAG laser treatment with and without Carisolv. First, Carisolv was applied on one-half of each carious lesions for 1 min and followed by the Er:YAG laser irradiation at 60-140 mJ, 2 Hz for another 1 min; the other half was treated with Er:YAG laser only. The cavity was carefully assessed by DIAGNOdent. Each lesion was photographed before and after treatment, and the treated cavity was observed by microscopy and with scanning electron microscope (SEM). RESULTS: Our results revealed that application of Carisolv followed by Er:YAG laser irradiation at 100-140 mJ pulse energy effectively removed dentin caries. From the SEM study, it was found that the cavity surface treated with the laser revealed various patterns of microirregularity, often accompanied by microfissure propagation. There was also no smear layer. CONCLUSIONS: It was revealed that Er:YAG laser and Carisolv could provide an alternative technique for caries removal for conventional mechanical drilling and cutting.     

Skin resurfacing improved with a new dual wavelength Er:YAG/CO2 laser system: a comparative study

OBJECTIVE: The efficacy of a new dual wavelength Er:YAG and CO2 laser system was tested for skin resurfacing results on rabbits' ears and human facial skin. The dual wavelength laser delivers simultaneous pulses of low-energy CO2 and high-energy Er:YAG energies. Theoretically, combining the strengths of both laser types in one console should lead to improved clinical outcome. SUMMARY BACKGROUND DATA: The use of the laser for skin resurfacing and remodeling has dramatically increased over the past few years. The CO2 laser was the first laser to be used in this field, followed more recently by the E:YAG laser. Both lasers offer unique advantages and disadvantages. METHODS: The present study consists of an ear chamber experiment, conducted on eight rabbits, to examine vascular network formation, after laser resurfacing with a standard CO2 laser and the Er:YAG/CO2 laser. Resurfacing was also performed on human patients with the Er:YAG/CO2 laser and the results were compared with previously published results of CO2 laser resurfacing. RESULTS: Significant advantages, including an attenuation in the degree of edema and erythema and a shorter reepithelialization time compared to results with conventional CO2 systems, were observed with the Er:YAG/CO2 system. Improved tissue reorganization and good clinical results in nine of the ten patients (six ratings of "very good" and three "good") were observed. The clinical outcome of the remaining patient was rated as "fair." Minimal side effects were reported and observed in only three patients. The learning curve required to maximize the efficiency of the system is steep, however, requiring a thorough understanding of the different laser/tissue interactions associated with the two wavelengths. CONCLUSION: It is the authors' opinion that the dual wavelength Er:YAG/CO2 laser system offers a particularly efficient and flexible system to perform standard CO2 procedures for skin resurfacing with an improved clinical outcome, as well as other applications with the CO2 or Er:YAG energy delivered separately.     

Morphological study on the capability of Er:YAG laser irradiation for root canal preparation

OBJECTIVE: The purpose of this study was to evaluate morphologically the capability of Er:YAG laser irradiation for root canal preparation in vitro. Background Data: There have been no reports on root canal preparation using Er:YAG laser irradiation. METHODS: Forty extracted human teeth were divided randomly into two groups of 20. Laser irradiation was performed using three different sizes of fiber tips at the two different parameters (G 1, 2 Hz and 136-184 mJ/pulse; G 2, 2 Hz and 170-230 mJ/pulse). After laser irradiation, the teeth were bisected longitudinally and observed by stereoscopy and field emission-scanning electron microscopy (FE-SEM). The time required for preparation in each group was recorded and the achievement degree of root canal preparation was scored according to our criteria. Statistical analysis of the times was performed using one-way analysis of variance (ANOVA). A value of p < 0.01 was considered significant. RESULTS: Root canals were prepared using laser irradiation at 50% of teeth in G 1 and 40% in G 2. Remnant pulp tissue after laser irradiation was observed at 30% of teeth in G 1, but not recognized in G 2. Irradiated areas were scale-like and clean, but rough and irregular by FE-SEM. The statistical analysis revealed that the time required for preparation at high energies was significantly shorter compared with that at low energies (p < 0.01). CONCLUSION: These results suggest that Er:YAG laser irradiation is capable of root canal preparation if appropriate parameters are selected.     

Caries-preventive effect of Er:YAG laser irradiation with or without water mist.

OBJECTIVE: This investigation was performed to evaluate the effect of Er:YAG laser irradiation on the acquired acid resistance of sound dental hard tissues to artificial caries formation by spectrophotometry, and the ultrastructure of lased areas was investigated by scanning electron microscopy (SEM) in vitro. BACKGROUND DATA: Although an Er:YAG laser has shown the most promise for hard tissue ablation, there have not been any dissolution studies to determine if this laser is suitable for caries preventive treatments. METHODS: An Er:YAG laser was used to irradiate the enamel and dentin samples from 20 extracted human molars at 400 mJ pulse energy with or without water mist. Samples were subjected to 2 microL of 0.1 M lactic acid solution (pH 4.8) for 24 hours at 36 degrees C. The parts per million (ppm) of calcium ion (Ca2+) dissolved in each solution was determined by atomic absorption spectrophotometry and the morphological changes were investigated by SEM. RESULTS: The lowest mean Ca2+ ppm was recorded in the samples irradiated without water mist, in those by irradiated with water mist, and in the unlased samples. SEM observation showed that the lased areas had melted and seemed to be thermally degenerated when irradiated without water mist. After acid demineralization, the thermally degenerated enamel or dentin surfaces were almost unchanged. CONCLUSIONS: The results of this study suggest that Er:YAG laser irradition with and without water mist appears to be more effective for caries prevention.     

Tensile bond strength of dentin-resinous system interfaces conditioned with Er:YAG laser irradiation

OBJECTIVE: The aim of this in vitro study was to assess tensile bond strength of dentin-resinous system interfaces conditioned with Er:YAG laser irradiation. BACKGROUND DATA: There are different results reported in the literature which relate to laser Er:YAG effects on dentin surface as a pretreatment during adhesives procedures. MATERIALS AND METHODS: Forty-two surfaces of human dentin from third upper molar were used after being extracted and kept in the refrigerator in 0.5% chloramines aqueous solution and then divided into three experimental groups and three control groups. The chosen restorative systems were Alert (Jeneric/Penton), Prodigy (Kerr Co.), and Z-100 (3M Co.), with correspondent dental adhesives Bond 1, Optibond Solo, and Single Bond, respectively. To conduct tensile tests, a special system of pairs of rods aligned in a specific apparatus was used, in accordance with ISO/TR 11405 standard (1994). RESULTS: By means of statistical analysis, the Kruskal Wallis test, it was noticed that group IE (laser + acid + Alert), 18.89 MPa, differed considerably from group IC (acid + Alert), 8.03 MPa (p < 0.10), but did not differ from the other groups. Group IIC (acid + Prodigy), 19.88 MPa, differed from group IIE (laser + acid + Prodigy), 12.57 MPa (p < 0.05), but did not differ from groups IIIE (laser + acid + Z-100), 14.11 MPa, and IIIC (acid + Z-100), 19.58 MPa. Group IIIE did not differ statistically from group IIIC. CONCLUSION: It was concluded that previous Er:YAG laser treatment on the dentinal structure only improved the tensile bond resistance of the Alert restorative system.     

Endodontic treatment with application of Er:YAG laser waveguide radiation disinfection

OBJECTIVE: The objective of this study is to examine the ability of Er:YAG laser radiation. Using a movable waveguide helps to obtain an antibacterial effect, not only in root canal walls but also in the surrounding tissues. BACKGROUND DATA: Conventional endodontic treatment is not fully effective due to microbial colonization of root canal walls dentin in premolars and molars. Various laser systems seem to be effective to kill the remaining microbial content in the root canal. The problem is in the flexibility of laser system tips. MATERIALS AND METHODS: The Er:YAG laser system was designed with a fluorocarbon polymer-coated silver hollow glass waveguide. Root canal systems of 44 premolars and molars were treated endodontically, using a step-back technique; 10 teeth were then treated with calcium hydroxide paste, and 22 teeth were irradiated by a movable waveguide. Before and after treatment, the colony-forming units were counted to determine 21 various microorganisms. RESULTS: Classical enlargement and shaping of the root canal is effective in 60%. Application of calcium hydroxide prepares sterile root canal in 80%. Er:YAG laser irradiation via movable waveguide (energy of 100 mJ, 30 pulses, repetition rate 4 Hz) can ensure residual disinfection of the root canal. CONCLUSION: Application of Er:YAG laser radiation through a flexible waveguide helps to attain antibacterial effect, not only in the root canal walls, but also in the surrounding tissues. Therapeutic doses of laser radiation guarantee one-step disinfection, including of anaerobic microorganisms.     

Effect of blended CO2 and erbium:YAG laser irradiation on normal and keloid fibroblasts: a serum-free study

OBJECTIVE: The purpose of this study was to determine the effect of combined CO2 and Er:YAG laser irradiation on normal (NF) and keloid (KF) facial dermal fibroblast production of TGF-beta1 and bFGF. BACKGROUND DATA: Keloids produce excess collagen. TGF-beta1 is integral to the growth and stimulation of fibroblasts and collagen; bFGF inhibits collagen synthesis. TGF-beta1 and bFGF production influence wound healing and may be manipulated by laser irradiation. MATERIALS AND METHODS: Human normal fibroblasts (NF) and keloid fibroblasts (KF) (2 x 10(4) cells/mL in serum-free media) were exposed to 1.7 J/pulse Er:YAG laser energy and CO2 delivered at either 3 or 5 W and at a duty cycle of 25%, 50%, or 100%. TGF-beta1 and bFGF were assayed using a quantitative ELISA. RESULTS: KF demonstrated a statistically significant mean population doubling time (PDT) when compared with NF (p=0.01). Irradiated KF and NF had longer PDTs than controls. All NF, excluding one irradiated group, and the three KF treated with 3 W secreted more bFGF than controls. Irradiated KF secreted less TGF-beta1 than controls. Significance was reached with the two groups exposed to 3 W at a duty cycle of 25% and 50% (p=0.04 and 0.05, respectively). All irradiated NF secreted less TGF-beta1 than controls. CONCLUSION: The combined CO2 and Er:YAG laser increased the release of bFGF, which has been shown to promote tightly organized collagen bundles, and decreased the concentration of TGF-beta1, which has also been shown to promote fibrosis formation. This laser may have a future role in keloid treatment, as well as normal facial scar prevention.     

Ablation depths and morphological changes in human enamel and dentin after Er:YAG laser irradiation with or without water mist

OBJECTIVE: This investigation was performed quantitatively to determine the ranges of ablation and to evaluate the morphological changes in human enamel and dentin irradiated by Er:YAG laser with or without water mist. SUMMARY BACKGROUND DATA: Recently, several infrared lasers have been introduced in the dental clinic to remove carious dental hard tissues in anticipation of replacing the high-speed dental drill. Among them, the Er:YAG laser has shown the most promise for hard tissue ablation. METHODS: An Er:YAG laser was used to ablate human dental hard tissues using a pulse energy that ranged from 100 to 400 mJ at a frequency of 2 Hz for 5 seconds. Ablation rates with or without water mist at different pulse energies were measured, and the morphological changes on enamel and dentin were also investigated by stereomicroscopy and scanning electron microscopy (SEM). RESULTS: The relationship between ablation depths and energies was almost linear at both enamel and dentin samples. The irradiation with water mist reduced the ablation depths, but only minimally, when compared to those irradiated without water mist. Morphological findings by SEM indicated that Er:YAG laser irradiation with water mist could produce the cavities without signs of thermal damage to the surrounding enamel and dentin. CONCLUSIONS: The results of this study suggest that addition of a fine water mist directed at the ablation sites does not greatly decrease the ablation, and does not cause any carbonization and melting in the surrounding dental hard tissues.     

龈下刮治和根面平整术联合Er:YAG激光、Nd:YAG激光治疗牙周炎的研究进展

牙周炎是发生于牙周支持组织的慢性炎症性疾病,以牙周支持组织的进行性破坏为主要特征,是最常见的口腔疾病之一.龈下刮治和根面平整术(SRP)是治疗牙周炎最重要且最有效的非手术治疗方式,但其也有许多不足,如难以全部刮除深牙周袋、部分窄小的根分叉区域的牙结石及菌斑.近年来许多辅助治疗手段相继出现,激光广泛应用于牙周炎的辅助治疗...     

Microleakage of a resin sealant after acid-etching, Er:YAG laser irradiation and air-abrasion of pits and fissures.

OBJECTIVE: The aim of this in vitro study was to assess microleakage underneath a filled pit-and-fissure sealant bonded to occlusal surfaces treated by four enamel etching techniques. SUMMARY BACKGROUND DATA: There has been no report of a study assessing microleakage of a pit-and-fissure sealant, comparing acid-etching, Er:YAG laser and air-abrasion for treating enamel surface. METHODS: Forty extracted human third molars were selected and randomly assigned into four groups of ten teeth: group I, the occlusal surfaces were acid-etched; group II, a very short pulsed Er:YAG laser was used to treat the surfaces; group III, aluminum oxide air-abrasion was associated with acid-etching; group IV, Er:YAG laser was associated with acid-conditioning. The surfaces were sealed and the teeth were stored for 7 days in distilled water. Then, specimens were thermocycled, immersed in a 0.2% rhodamine solution, sectioned, and analyzed for leakage using an optical microscope connected to a video camera. The images were digitized and analyzed by software that allowed microleakage assessment in millimeters. RESULTS: Statistical analysis showed that occlusal surfaces treated exclusively by the Er:YAG laser (group II) provided the poorest marginal sealing and that acid-etching (group I) was statistically similar to aluminum oxide air-abrasion + acid etching (group III) and to Er:YAG laser + acid-etching (group IV). CONCLUSIONS: The results suggest that complementing either air-abrasion or Er:YAG laser irradiation with a subsequent acid-conditioning did not lessen microleakage at the enamel-sealant interface when compared with an acid-etched group. It was also observed that treating the enamel surface exclusively by Er:YAG laser resulted in the highest degree of leakage.     

Analysis of surface roughness of enamel and dentin after Er,Cr:YSGG laser irradiation.

OBJECTIVE: The purpose of this investigation was to compare the surface roughness of enamel and dentin following the Er,Cr:YSGG laser irradiation and acid etching. BACKGROUND DATA: Laser-roughened enamel or dentin surfaces have been expected to enhance restorative materials bond strength. MATERIALS AND METHODS: Er,Cr:YSGG laser irradiation was performed in one half of each polished enamel or dentin sample at 3 W (33.9 J/cm2, with air 70% and water 20%,) pulse energy for 6 sec. Then the other half was treated with 37% phosphoric acid for 30 sec. Surface roughness and morphological studies were performed. Results: It was found that surface roughness was significantly increased with the laser system. Scanning electron microscopy analysis showed that irradiated surface produces a rough surface that was completely lacking of a smear layer; there was also no cracking of enamel or dentin. CONCLUSION: Er,Cr:YSGG laser irradiation could provide an effective and alternative method to the acid etch technique.     

Study of microleakage at class V cavities prepared by Er:YAG laser using rewetting surface treatment

OBJECTIVE: This study was conducted to analyze microleakage in Class V cavity preparation, using rewetting (or not) just after burr or Er:YAG laser preparation of enamel and dentin walls in permanent teeth. Background Data: Several studies reported microleakage around composite restorations when cavity preparation was done or treated by Er:YAG laser. As the hybridized laser is removed when this laser is used to cut dental hard tissue, there is a need for new materials or techniques to minimize gaps and microleakage. RESULTS: Primer solution showed significant effect in enamel and dentin, at the level of 5%, when Er:YAG laser was used as a cutting tool. Using primer solution after phosphoric acid in preparations with the laser, microleakage was similar in degree to when cavities were prepared with the burr. CONCLUSION: Re-wetting surface just after Er:YAG irradiation and chemical treatment with phosphoric acid using HEMA aqueous solution seems to improve the quality of bioattachment between the adhesive system and enamel/dentin, showing similarities between restoration behaviors independently of the cutting tool, whether burr or laser.     

Preparation of root canal orifices by Er:YAG laser irradiation: in vitro and clinical observations

OBJECTIVE: The purpose of the present study was to evaluate the effectiveness of Er:YAG laser irradiation for preparation of root canal orifices in extracted human teeth and several clinical cases. Background Data: Few studies with sufficient data have been conducted in this area. MATERIALS AND METHODS: Orifices of 42 extracted human teeth were prepared by conventional methods using a Peeso reamer or Er:YAG laser device at 250 mJ/pulse and 8 Hz. In the clinical study, the orifices of 11 teeth from 11 patients with irreversible pulpitis were prepared by Er:YAG laser irradiation at 160 mJ/pulse and 8 Hz. Teeth were carefully irradiated using non-contact methods. Evaluation was performed by visual inspection, stereoscopy, radiography, and scanning electron microscopy (SEM). In addition, the efficiency of using the Er:YAG laser was evaluated. RESULTS: In the in vitro study, canal orifices were clearly exposed by laser irradiation in all specimens. In 31 of 36 teeth (86%), orifices were successfully prepared without ledge formation or perforation. SEM observations revealed that irradiated surfaces were slightly rough and scaly, but essentially free from debris and smear layer. In the clinical study, orifices were successfully prepared in 10 of 11 teeth (91%), and no ledge formation or perforation was observed. CONCLUSION: These results suggest that the preparation of root canal orifices by Er:YAG laser irradiation may be useful in most cases, if appropriate parameters are selected.     

Histological alterations after irradiation of cartilage using Ho:YAG laser

OBJECTIVE: The authors carried out an experimental study to evaluate the histological alterations after irradiation of cartilage using Holmium:YAG (Ho:YAG) laser VersaPulse Select 60 watts and Infra Tome Delivery Systems 30 degrees Handpiece (spot size at fiber tip 0.4 mm; Coherent Medical, Palo Alto, CA). BACKGROUND DATA: Recently, some authors reported cases with articular cartilage damage following arthroscopic laser surgery in the knee joint for the treatment of articular cartilage or meniscal pathology. MATERIALS AND METHODS: The cartilage specimens immersed in saline were exposed to Ho:YAG laser irradiation. The laser wavelength was 2.1 microm, and pulse duration was 250 microsec. Power settings were 0.2-1 joules per pulse and 10-15 Hz. Total laser energy used in these procedures was 1.5 K joules. During the procedures, the handpiece was used at an angle of 30 degrees and at a distance of 1 mm. RESULTS: Electron microscopic evaluation demonstrated that the ultrastructure of the cartilage is preserved in both experiment and control groups. CONCLUSION: When Ho:YAG laser is used in optimal dosage (optimal joule and Hertz) with optimal technique (keeping the handpiece at an appropriate angle and distance) and avoiding overtreatment, it does not cause cartilage damage.     

Er:YAG laser versus Blue Peel in the treatment of photoaging hands

OBJECTIVE: This study aims at comparing the effects of Er:YAG laser and Blue Peel on the treatment of photoaged hands. BACKGROUND DATA: The face and hands are constantly being exposed to sunlight, which causes early skin aging and damage. Currently, there are many studies showing how to deal with photoaging of the face; however, very few have investigated treatment of photoaging of the hands, whose skin properties differ from the face. MATERIALS AND METHODS: We studied the effects (edema, erythema, temperature, reepithelialization) of laser and Blue Peel on the hands of 22 patients. The follow-up was 3 months. RESULTS: Edema, erythema, and temperature were more intense in the Er:YAG group during the early postoperative days, but those clinical parameters became similar to the ones observed in the Blue Peel group over time. Forty-five percent of the patients considered the results of Er:YAG treatment excellent, while 16.67% rated the treatment with Blue Peel as excellent. CONCLUSION: Both methods showed very good clinical results, but Er:YAG laser treatment satisfied the patients the most.     

Morphological and microleakage studies of the cavities prepared by Er:YAG laser irradiation in primary teeth

OBJECTIVE: The purposes of this study were to investigate cavity surfaces morphologically, and compare microleakage at cavities prepared by Er:YAG laser after composite resin restoration versus conventional mechanical treatment in human primary teeth in vitro. BACKGROUND DATA: There have been few reports on microleakage at cavities prepared by Er:YAG laser irradiation. MATERIALS AND METHODS: A total of 30 cavities (class V) in human primary teeth were used. Half of the cavities were prepared by an Er:YAG laser system at 300 mJ pulse energy and 4 Hz, and the other half were prepared with a high-speed diamond bur. Five cavities from each group were investigated by scanning electron microscopy (SEM) and histopathological examination. Remaining cavities were filled with a composite resin without an acid-etching technique and then subjected to microleakage test in 0.6% rhodamine B solution under thermocycling. RESULTS: Microleakage (score: 2.45 +/- 1.07) at cavities prepared by laser was significantly less than that by bur (score: 1.30 +/- 0.95; p < 0.05). SEM observation showed that, compared with the relatively flat appearance of cavities prepared by bur, cavity margins prepared by laser were irregular but there was almost no smear layer at the cavity walls. CONCLUSION: It can be concluded that cavity surfaces prepared by Er:YAG laser are irregular, but microleakage at cavities prepared by the laser after filling with composite resin is better than that by mechanical bur using the dye penetration method.     

Effects of the Er:YAG laser irradiation on titanium implant materials and contaminated implant abutment surfaces

OBJECTIVE: The purpose of this study was to examine the morphological changes and temperature increases of the titanium after Er:YAG laser irradiation, and also to investigate the effect of this laser on debridement of contaminated healing abutments. BACKGROUND DATA: Mechanical instruments have been used for the cleaning of implant abutment surfaces, however, most of them are not appropriate for the application to titanium surface. Recently, the Er:YAG laser has been expected to have a promising ability for the debridement of implant surface. MATERIALS AND METHODS: Experiments were composed of three parts. At first, ten titanium round plates were exposed to the Er:YAG laser irradiation at 30-200 mJ/pulse and the surface changes were observed by stereomicroscope and scanning electron microscope. Secondly, the surface temperature changes of 60 titanium plates during and after Er:YAG laser irradiation at 30 and 50 mJ/pulse were measured by thermographic equipment. At last, calculus on the surface of six contaminated healing abutments was removed by Er:YAG laser or ultrasonic scaler, and the treated surfaces were examined by stereomicroscope. RESULTS: Under 50 mJ/pulse, distinct morphological changes were not observed and the elevation of surface temperature was minimal, especially in the use of water-cooling. The Er:YAG laser at 30 mJ/pulse and 30 Hz with water spray was capable of effectively removing plaque and calculus on the implant abutments without injuring their surfaces. CONCLUSION: This study indicates that the Er:YAG laser can be a novel technical modality for the debridement of implant abutment surface.     

The bactericidal effect of Nd:YAG, Ho:YAG, and Er:YAG laser irradiation in the root canal: an in vitro comparison

OBJECTIVE: The aim of this study was to compare the antibacterial effectiveness of the Nd:YAG, the Ho:YAG, and the Er:YAG laser in infected root canals. SUMMARY BACKGROUND DATA: Lasers are gaining increasing importance in the field of endodontics. Numerous studies have shown the beneficial effects of laser treatment in disinfecting root canals. METHODS: In our in vitro experimental setup, 40 extracted and endodontically treated teeth were inoculated with a suspension of Escherichia coli and Enterococcus faecalis and then irradiated at standardized power settings. The disinfecting efficacy of each laser was proved by classical microbiological examination. RESULTS: This article highlights that all three lasers substantially decreased the bacterial population with only minimal differences in their microbicidal efficacy. At 1.5 W, the best results were obtained by the Er:YAG laser achieving a mean bacterial elimination of 99.64%, followed by the Nd:YAG laser (99.16%), and the Ho:YAG laser (99.05%). CONCLUSION: Our findings indicate that all three lasers act as strongly effective microbicides without causing unfavorable temperature rises at the settings used. They can thus be considered a valuable tool for root canal treatment.     

A study on the morphological changes of the rat mandibular bone with TEA CO2 laser

OBJECTIVE: The purpose of this study was to investigate the morphological changes of the bone structure induced by transversely excited, atmospheric TEA pressure CO2 laser irradiation. Moreover, the healing process at 3 weeks was also observed. SUMMARY BACKGROUND DATA: It has been demonstrated that dental hard tissue can be removed by a long pulse of TEA CO2 laser irradiation with minimal thermal damage. However, there are few studies on the morphological changes of the TEA CO2 laser on bone tissue. METHODS: The TEA CO2 laser was irradiated on the surface of the rat mandibular bone under the following irradiation conditions: wavelength, 10.6 microns; output, 95 mJ/pulse; pulse repetition rate, 1 Hz; irradiation time, 7.5 microseconds/shot; spot size, 0.8 x 1.5 mm; energy density, 7.9 J/cm2. Histological and scanning electron microscopic examinations were performed. RESULTS: In the stereoscopic examination, a defect with clean-cut margins was produced. In the light microscopic examination, a basophilic line at the bottom of the defect was noted. Examining the defect with SEM, a smear-like appearance and cone structures were found. In the histological examination, a healing process by formation of new bones at the junction site was recognized. CONCLUSIONS: These findings suggest that it is possible to remove bone tissues by TEA CO2 laser irradiation. However, a particle-like structure associated with a basophilic line and melted surface indicated that some thermal damage was produced during the laser irradiation.