Are laryngeal papilloma virus-infected cells viable in the plume derived from a continuous mode carbon dioxide laser, and are they infectious? A preliminary report on one laser mode

The purpose of this study was to determine the potential risk of transmitting viable viral infected cells as well as viral infectivity of laryngeal papilloma in the plume derived from a continuous mode carbon dioxide laser. Each of 10 juvenile recurrent laryngeal papilloma specimens was divided into two equal parts, and one part was irradiated with a carbon dioxide laser employing a continuous mode at the power setting of 10 watts with 0.5 mm spot size and a power density of 1667 W/cm2. The resultant laser plume was trapped and was cultured simultaneously with the other part of the specimen which served as the control. All irradiated specimens tested yielded negative culture results while all the control counterparts revealed viable cell growth. To detect the viral infectivity, laser plume was cultured with two separate cell systems, one was the porcine PS clone D cell line and the other normal mucosal cells obtained from the same patient, and to control these systems both cell lines were also designed to be infected with polio virus. Both cell lines in the viral infectivity testing systems revealed no sign of viral infection. The results suggest that papilloma virus-infected cells cannot survive the continuous mode of carbon dioxide laser irradiation. We primarily conclude that, to avoid airborne transmission of plume containing laryngeal papilloma viral-infected cells and infectious viral particles, the carbon dioxide laser parameters should be in a continuous mode with the power density equal to, or more than, 1667 W/cm2.     

Absence of human papillomavirus DNA in the plume of erbium:YAG laser-treated warts

BACKGROUND: The erbium:YAG laser (Continuum Biomedical, Dublin, Calif.) is a new resurfacing and ablating laser that produces minimal residual thermal damage. Laser safety requires careful attention to the hazards of the laser plume. It is important to know whether viable organisms survive in the vapors. Human papillomavirus (HPV) DNA has been detected in the vapor of carbon dioxide laser-treated and electrodesiccated human warts. The presence or absence of HPV DNA in the laser plume of erbium:YAG laser-treated warts has not been previously studied to our knowledge. OBJECTIVE: Our purpose was to determine the presence or absence of HPV DNA in the laser plume of erbium:YAG laser-treated human warts. METHODS: One half of clinically typical and histopathologically confirmed verrucae vulgares from five patients were submitted for HPV DNA detection with in situ hybridization. After erbium:YAG laser ablation of the remainder of the warts, the laser plume was deposited on the handpiece as an abundant fluffy material and was submitted for evaluation of HPV DNA by polymerase chain reaction with consensus primers for the HPV type detected in the wart specimens. RESULTS: HPV2 DNA was found in all warts. HPV DNA was not detected in the erbium:YAG laser plume after ablation of these same warts. CONCLUSION: The absence of HPV DNA in the plume of erbium:YAG laser-treated warts is a significant safety feature of this laser.     

Anti-B4-blocked ricin: a phase II trial of 7 day continuous infusion in patients with multiple myeloma

Skin ultrastructure was examined in patients undergoing CO2 laser resurfacing for facial rejuvenation. The lasers used in this study were the Coherent Ultrapulse CO2 laser with computerized pattern generator, the Sharplan Feathertouch laser, and the Laserscope Paragon-70 pulsed CO2 laser with computerized pattern generator. Results showed that the epidermis was totally removed with one pass of the CO2 laser. After one laser pass, there was little compaction of collagen in the dermis, but after two and three passes, there were sequential graded increases in collagen compaction with loss of the intervening extracellular gel matrix. There was no "collagen shrinkage," and the collagen itself was marginally affected, except for occasional losses in striations at the surface of the specimens. Elastin was very much affected by the laser such that with only one pass, the elastin was abnormal, presenting with a mottled heterogeneous structure. This elastin aberrancy was present in both the papillary and reticular dermis. After one laser pass, fibroblast necrosis was present in the papillary dermis and the reticular dermis (depending on which laser was used), and the extent and depth of necrosis increased with multiple laser passes.     

Cutaneous resurfacing with CO2 and erbium: YAG lasers: preoperative, intraoperative, and postoperative considerations

The development and integration of pulsed and scanned CO2 and erbium:YAG laser systems into mainstream surgical practice over the past years has revolutionized cutaneous resurfacing. These lasers are capable of delivering to skin high peak fluences to effect controlled tissue vaporization, while leaving an acceptably narrow zone of residual thermal damage. The inherent technological differences that exist between the two distant laser systems in terms of ablation depths, degree of thermal coagulation, and postoperative side-effects and complications guide patient selection and management. This article reviews the basic principles of CO2 and erbium:YAG laser resurfacing, including preoperative, intraoperative, and postoperative patient considerations. Side-effects and complications encountered after laser resurfacing are discussed with specific guidelines provided on their appropriate management. Anticipated future developments and cutting-edge research endeavors in cutaneous laser resurfacing are also briefly outlined.     

Diagnosis of small intestinal bacterial overgrowth in clinical praxis: a comparison of the culture of small bowel aspirate, duodenal biopsies and gastric aspirate

BACKGROUND/AIMS: This study was undertaken to validate the usefulness of the culture of duodenal biopsy specimens and gastric aspirate compared to the culture of small bowel aspirate for diagnosing small intestinal bacterial overgrowth. We also investigated the occurrence of predisposing conditions in these patients. METHODOLOGY: Seventy five consecutive patients, admitted because of symptoms which caused us to suspect small intestinal bacterial overgrowth, were studied. For all patients, specimens for the culture of small bowel aspirate, duodenal biopsies and gastric aspirate were obtained during upper endoscopy. RESULTS: Eighteen patients showed growth of gram negative bacteria, 22 growth of gram positive bacteria and 35 showed no significant growth in cultures of small bowel aspirate. Cultures of duodenal biopsies revealed gram negative bacteria in 11 patients, gram positive bacteria in 9 and no growth in 55. Cultures of gastric aspirate revealed gram negative bacteria in 7 patients, gram positive bacteria in 12 and no growth in 51. Ten of the 18 patients with gram negative overgrowth and 13 of the 22 patients with gram positive overgrowth had a predisposing condition. In contrast, only 4 of the 35 without overgrowth had a predisposing condition. CONCLUSIONS: The culture of duodenal biopsy specimens or gastric aspirate is a less sensitive method than the culture of small bowel aspirate. Most patients with culture-proven small intestinal bacterial overgrowth had at least one predisposing condition.     

Thermal injuries as a result of CO2 laser resurfacing

CO2 laser resurfacing of the face for fine wrinkles has gained great popularity over a short period of time. The use of the CO2 laser has proven to be effective in reducing or eliminating fine wrinkles. This tool in the surgeon's armamentarium has been added to those of dermabrasion and chemical peel. The theoretical advantage of the use of the CO2 laser for resurfacing has been better accuracy and reportedly more control of the depth of penetration. The use of the CO2 laser has been welcomed by many cosmetic surgeons. Until now, there have been few reported cases of complications with the use of the CO2 laser. To many, this would sound too good to be true; unfortunately, that is the case. The CO2 laser is a high-energy machine that can indeed cause thermal injury. This thermal injury can result in deep burns to the skin and hypertrophic scarring. We feel this is more common than is currently being reported, and we share our experience as a burn and wound care referral service. During an 18-month period, 20 consecutive patients were referred to our practice who had received injuries from the CO2 laser resurfacing laser. We present here in this review a summary of those injuries. The CO2 resurfacing laser is a very effective tool for the treatment of fine wrinkles, but it is not without the potential for serious complications. We urge caution with the use of the laser and prompt recognition and treatment of thermal injury to the skin.     

Ultrastructure of collagen thermally denatured by microsecond domain pulsed carbon dioxide laser

BACKGROUND: Clinical improvement in photodamaged skin after carbon dioxide (CO2) laser resurfacing is thought to result in part from thermal collagen shrinkage. The presence of such collagen has not been unequivocally demonstrated. To identify and characterize the morphological features of collagen after CO2 laser exposure, we irradiated ex vivo human facial skin and bovine calcaneus tendon with microsecond domain pulsed CO2 laser energy and examined specimens for histopathological and ultrastructural changes in collagen. OBSERVATIONS: In dermis and tendon, 3 zones of collagen structure were apparent on electron microscopy. The first, most superficial zone demonstrated loss of collagen structure. The second zone consisted of admixed normal collagen fibers and thickened collagen fibers. Zone 3 consisted of normal-appearing collagen fibers. CONCLUSIONS: Ultrastructural examination of irradiated collagen revealed distinct morphological zones of denatured collagen fibers. Partially denatured fibers had an increased diameter consistent with lineal shrinkage. Zonal distinction was undetectable by light microscopy. Ultrastructurally, the zones of denatured collagen located above the normal fibers correlated with the zone of altered material seen on light microscopy. These findings suggest that collagen fiber shrinkage does occur after pulsed CO2 laser irradiation and that this phenomenon contributed, at least in part, to the immediate tissue contraction observed clinically.     

Traumatic urethral disruption: a protocol for diagnosis

BACKGROUND: Many patients who request cutaneous carbon dioxide (CO2) laser resurfacing for correction of periorbital rhytides also complain of "dark circles" under their eyes. OBJECTIVE: This study was conducted in order to determine the effectiveness of high-energy pulsed CO2 laser treatment in reducing infraorbital hyperpigmentation. RESULTS: Significant lightening of infraorbital hyperpigmentation was observed 9 weeks following CO2 laser resurfacing. Melanin reflectance spectrometry readings did not correlate with clinical findings. CONCLUSIONS: This study represents the first report of the successful use of a non-pigment-specific laser system for the treatment of infraorbital dark circles. The lack of correlation of melanin spectrometry readings with clinical assessment likely represents an insufficient follow-up time period.     

Carbon dioxide laser resurfacing. Long-term follow-up in 2123 patients

Carbon dioxide (CO2) laser resurfacing has become increasingly popular as a method of facial rejuvenation, enabling the surgeon to repair sun-damaged skin, wrinkles, and acne scars precisely. This article presents the results of the authors' histologic studies with all of the current CO2 laser systems as well as the conclusions of her experience with 2123 patients over a 5-year period. Improvements obtained from CO2 laser resurfacing appear to be long lasting, especially when combined with other procedures, and it is likely that laser resurfacing will remain in the armamentarium of facial rejuvenation for some time.     

Histologic effects of the high-energy pulsed CO2 laser on photoaged facial skin

To delineate the histologic effects of laser resurfacing at photoaged skin, a protocol was designed to biopsy laser test sites in conjunction with adjacent actinically damaged skin at the time of rhytidectomy. Five patients with photodamaged skin underwent resurfacing of the preauricular region to examine the effect of increasing pulse energy and increasing number of passes on depth of dermal penetration. Histologic examination of these specimens showed that the depth of laser injury was dose-dependent. Increasing pulse energy created a deeper wound, and increasing the number of passes similarly produced a larger band of necrosis. Ten patients with photodamaged skin underwent resurfacing of the preauricular region 15 days to 6 months prior to undergoing a rhytidectomy. A comparison of the laser-resurfaced test spot with the adjacent untreated photodamaged skin demonstrated consistent histologic changes to both epidermis and dermis in all specimens examined. Following laser resurfacing, epidermal atrophy and atypia were eliminated, and all specimens exhibited a regeneration of epithelium that was normal in its morphology. Melanocytic hypertrophy and hyperplasia were corrected following treatment, although density and function of epidermal melanocytes appeared normal. All specimens exhibited a substantial amount of neocollagen formation involving both the superficial and middermis following resurfacing. In association with new collagen development within the dermis, there was noted to be a similar degree of proliferation of elastic fibers, as well as a diminution of glycosaminoglycans, which are typically present in actinically damaged elastotic dermis. To determine the effect of laser resurfacing on-black skin, laser test spots were placed in the postauricular region of three black patients. Biopsy of these test sites showed that the histologic effects of laser resurfacing were similar to those observed in Caucasian patients, with complete repopulation of epidermal melanocytes in specimens biopsied 3 months following resurfacing. The histologic effects of laser resurfacing are microscopically similar to those of phenol peeling in terms of the amelioration of photodamage. The distinction between these two treatment methods lies in their apparent effect on epidermal melanocytes, which appear to function normally following laser resurfacing.     

Feasibility of collecting disease reports from relatives for genetic epidemiologic investigations

BACKGROUND: For many years, the treatment of facial wrinkles has been performed exclusively by dermabrasion, chemical peeling, or surgical face lifting. However, the recently introduced carbon dioxide lasers which emit ultrashort coherent light beams enable the cosmetic surgeon to ablate superficial epidemic layers with absent or very limited side effects. The purpose of this paper is to compare laser skin resurfacing with classical face lifting and discuss the potentials and limitations of each method. METHODS AND PATIENTS: Three patients suffering from facial wrinkles on photoaged skin were treated with the ultrapulsed CO2 laser (UltraPulse 5000 C; wavelength 10,600 nm, pulse duration 0.6 to 0.9 ms, maximum pulse energy 500 mJ). This laser guarantees vaporization of very thin superficial skin layers without scarring and with minimizing lateral thermal injury due to extreme short pulse duration. A special handpiece (CPG) permits an exact approach and a bloodless ablation of relatively large areas of facial skin. The fourth patient underwent a surgical face lift due to the depth of wrinkles. RESULTS: Excellent cosmetic results were achieved in all three patients with superficial wrinkles who were treated by laser skin resurfacing. When treating deeper wrinkles, e.g., glabella or nasolabial fold, the surgical face lift is the preferred method. CONCLUSION: Ultrapulsed CO2 laser treatment expands the therapeutic options for superficial facial wrinkles, especially for perioral, periorbital, forehead, and cheeks wrinkles. It proves to be a safe and effective method with very limited if any side effects. Nevertheless, deeper wrinkles are still a domain of the classical face lift. The combination of both methods may improve the overall outcome in the future.     

Skin resurfacing of facial rhytides and scars with the 90-microsecond short pulse CO2 laser. Comparison to the 900-microsecond dwell time CO2 lasers and clinical experience

BACKGROUND: Carbon dioxide lasers that produce either short pulses or scanned continuous beams have been used for skin resurfacing to improve wrinkles or scars. Using a high peak power, short pulse CO2 laser can produce clinically effective results with minimal thermal damage. OBJECTIVE: To evaluate the effectiveness of skin resurfacing using the 90-microsecond pulse duration CO2 laser compared to other laser systems. Erythema, healing time, complications, and histological measurement of the depth of ablation and thermal damage per pass with this system were also assessed. METHODS: Forty-one patients with facial rhytides and scars underwent resurfacing with a 90 microseconds pulse duration CO2 laser. Using patient survey, patients were evaluated for effectiveness of therapy, healing time, and complication rates. Comparisons of histologic and clinical findings were made with different short pulse CO2 lasers. RESULTS: Healing time, duration of erythema, and post-operative pain were less with the 90 microseconds pulse CO2 laser than with the 900-microsecond dwell time and 950-microsecond pulse duration lasers, while effectiveness was comparable. Complications were few with the 90-microsecond pulse laser, including three patients (9.1%) developing hyperpigmentation. One pass with the 90-microsecond pulse duration CO2 laser produced 100 microns of ablation with 17 microns of thermal damage. Ablation and damage were additive so that, by six passes, ablation depth was 350 microns and depth of thermal damage was 63 microns. This thermal damage is less than that reported with lasers having a longer pulse duration or dwell time with comparable depths of vaporization. CONCLUSION: Treatment with the 90-microsecond pulse duration laser results in a more rapid healing time and shorter duration erythema. The clinical improvements in wrinkles and sun damage were comparable. The 90-microsecond pulse duration laser provides an effective, predictable, and safe means of improving facial rhytides and scars.     

Bi-level positive airway pressure (BiPAP) ventilation in an infant with central hypoventilation syndrome

OBJECTIVES: To determine the effects of long-term cigarette smoking on the levels of plasma testosterone, luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in male adult rats and to examine morphological and histological changes in the testes. MATERIALS AND METHODS: Cigarette smoke was generated by a smoking-machine and 12 rats were exposed to cigarette smoke diluted with 90% air for 60 days (2 h/day). Twelve rats were exposed to room air only under similar conditions as controls. The concentrations of plasma testosterone, LH and FSH were measured before and after exposure using a radio-immunoassay and the testes were examined histologically. RESULTS: In rats exposed to smoke, the mean plasma testosterone level decreased significantly but there were no significant changes in testosterone in the control rats. The mean plasma LH and FSH levels of the two groups did not change significantly after exposure. In rats exposed to smoke, histological examination of the testes showed fewer Leydig cells and degeneration of the remaining cells. CONCLUSION: These results indicate that the decrease in plasma testosterone levels induced by exposure to smoke was not associated with changes in plasma gonadotrophin levels. The decrease in testosterone levels may be related to the toxic effects of smoke on Leydig cells.     

When life is ending, there is the right to death with dignity

BACKGROUND: This report summarizes an institutional review board-approved 6-month study with the NovaPulse carbon dioxide (CO2) laser utilizing the NovaScan handpiece in facial skin resurfacing applications. OBJECTIVE: This study comprised the initial clinical evaluation (pre-FDA approval) of this device. METHODS: A total of 54 patients underwent 56 laser procedures: 36 full face and 20 regional procedures. RESULTS: Following healing, there was a 91% satisfaction rate. The mean laser-on times were: full face, 27 min; perioral, 7 min; periorbital, 3 min; glabellar, 2.5 min; scar, 5 min; and epidermal lesions, 6 min. CONCLUSIONS: The NovaScan CO2 laser handpiece is a safe tool for skin resurfacing. In its initial use over a 6-month period there were no device-related complications.     

Optimizing fluence and debridement effects on cutaneous resurfacing carbon dioxide laser surgery

OBJECTIVE: To develop methods to compare carbon dioxide (CO2) resurfacing lasers, fluence, and debridement effects on tissue shrinkage and histological thermal denaturation. DESIGN: In vitro human or in vivo porcine skin samples received up to 5 passes with scanner or short-pulsed CO2 resurfacing lasers. Fluences ranging from 2.19 to 17.58 J/cm2 (scanner) and 1.11 to 5.56 J/cm2 (short pulsed) were used to determine each laser's threshold energy for clinical effect. Variable amounts of debridement were also studied. MAIN OUTCOME MEASURES: Tissue shrinkage was evaluated by using digital photography to measure linear distance change of the treated tissue. Tissue histological studies were evaluated using quantitative computer image analysis. RESULTS: Fluence-independent in vitro tissue shrinkage was seen with the scanned and short-pulsed lasers above threshold fluence levels of 5.9 and 2.5 J/cm2, respectively. Histologically, fluence-independent thermal depths of damage of 77 microns (scanner) and 25 microns (pulsed) were observed. Aggressive debridement of the tissue increased the shrinkage per pass of the laser, and decreased the fluence required for the threshold effect. In vivo experiments confirmed the in vitro results, although the in vivo threshold fluence level was slightly higher and the shrinkage obtained was slightly lower per pass. CONCLUSIONS: Our methods allow comparison of different resurfacing lasers' acute effects. We found equivalent laser tissue effects using lower fluences than those currently accepted clinically. This suggests that the morbidity associated with CO2 laser resurfacing may be minimized by lowering levels of tissue input energy and controlling for tissue debridement.     

Assessment of the psychotropic activity of analogs of cholecystokinin tetrapeptide fragment]

BACKGROUND: Both dermabrasion and high-energy pulsed carbon dioxide (CO2) laser resurfacing can improve the appearance of surgical scars. Although the results of these two procedures have been compared using historical data, a prospective evaluation has never been performed in humans. OBJECTIVE: To prospectively compare the clinical effects of dermabrasion and high-energy pulsed CO2 laser resurfacing in the revision of surgical scars. METHODS: Facial surgical scars in four patients were prospectively revised using a split scar model. One half of the scar was dermabraded and the other half was resurfaced with the high-energy pulsed CO2 laser. Comparisons of the two treatment modalities were performed through clinical assessment, photographic evaluation, and textural analysis of the scars. RESULTS: The high-energy pulsed CO2 laser-resurfaced halves of the scar were bloodless with less postoperative crusting in comparison with the dermabraded halves. Reepithelialization time and degree and duration of postoperative erythema were similar for both treatment halves. Photographic evaluation and textural analysis showed comparable improvement in the clinical appearance and surface texture of the scars with both treatment modalities. CONCLUSIONS: Both the high-energy pulsed CO2 laser and dermabrasion can achieve comparable clinical improvement in the revision of surgical scars. The high-energy pulsed CO2 laser offers the advantage of a bloodless field and a more precise method of tissue ablation. Postoperative erythema, however, is an expected finding with both treatment modalities.     

Effects of rapid pulsed CO2 laser beam on cortical bone in vivo

Twenty rabbit femurs were used to study the effect of CO2 laser on cortical bone. Sixteen femurs were treated with 20 watts, 3 mm defocused beam, 2 KHZ spike pulse mode CO2 laser for 10 seconds through a circular window in the metaphysis. In four control femurs, the inner cortex was exposed without laser treatment. The animals were killed at 4 and 6 weeks and the specimens studied histologically. All laser-treated specimens showed thermal changes. Three histological zones were observed. A superficial zone of inner cortex close to the beam consisted mainly of carbonization or carbon ash during resorption. An intermediate zone consisted of bone necrosis and healing with associated areas of new bone formation. The deep zone of outer cortex had normal bone with no cellular damage. No such changes were observed in the control specimens. The CO2 laser can be used to generate a controlled zone of tissue ablation, which may make it a potentially useful tool for tumor margin cauterization.     

Wuchereria bancrofti microfilariae in the dentigerous cystic fluid: an unusual presentation

The Glidewire (Microvasive, Natick, MA) or Terumo wire (Terumo, Japan) is constructed with a hydrophilic polymer surface that enables easier passage through narrowed lumens in the urinary tract. This study examined the effects of gas sterilization on Glidewire surface structure, slipperiness, and ability to support bacterial growth. Light microscopy at 100x and 400x and scanning electron microscopy at 100 to 1300x were used to compare the surface tips of five new 0.038-inch Glidewires with those resterilized one or three times. The tips were immersed in water prior to standard gas sterilization for operating room equipment. Subjective evaluation of slipperiness involved asking 10 blinded urologists to assess the nature of new and resterilized wires by feel. Support of bacterial growth was assessed by comparing cultures performed on new wires (control) with those of wires incubated with Bacillus stearothermophilus. Microscopy, reviewed by a pathologist, revealed no perceivable surface differences after one and three gas sterilizations. Eight of the urologists noted similar or improved slipperiness of resterilized wires compared with new wires. Bacterial cultures of intentionally infected wire segments showed no growth after standard gas sterilization in all cases. In this study, gas sterilization did not adversely affect the lubricious nature or the surface coating of the hydrophilic coating of Glidewires. Also, gas resterilization was bactericidal to new and used wires that had been infected with a heat-tolerant organism.     

Effect of therapeutic concentrations of nitric oxide on bacterial growth in vitro

OBJECTIVES: Besides its vasodilative actions, nitric oxide (NO) is also involved in host defense on a cellular level. We studied the antimicrobial properties of NO in concentrations used with inhaled NO therapy for the treatment of pulmonary hypertension in neonates. DESIGN: In vitro study of bacterial growth of five species, with and without NO exposure. SETTING: Level IV neonatal intensive care unit at a university children's hospital. SUBJECTS: In vitro bacterial cultures. INTERVENTIONS: We tested ten different strains of five bacterial species (Staphylococcus aureus, Staphylococcus epidermidis, group B streptococcus [GBS/Streptococcus agalactiae], Escherichia coli, and Pseudomonas aeruginosa), derived from the tracheal isolates of ventilated premature and term infants. Cultures were exposed to three different concentrations of NO (40, 80, and 120 parts per million [ppm]) and bacterial growth was compared with the same strains incubated in ambient air for 24 hrs. After incubation (with or without NO), colony-forming units were counted. MEASUREMENTS AND MAIN RESULTS: Bacterial growth of S. aureus, E. coli, and P. aeruginosa was not reduced with the NO concentrations applied. The number of colony-forming units of S. aureus increased at 80 ppm of NO. Growth of S. epidermidis and GBS was significantly affected at 120 ppm, resulting in decreased numbers of colony-forming units as compared with controls exposed to ambient air. CONCLUSIONS: We conclude that NO has a selective bacteriostatic effect on some of those bacteria most commonly cultured in tracheal specimens of premature infants and neonates. This effect appears to be dose-dependent and occurs in the upper range of dosages used with inhaled NO therapy. However, in the range of dosages applied in ongoing controlled trials of inhaled NO in neonates and premature infants (1 to 80 ppm), a bacteriostatic effect of NO is not to be expected.     

Melanoma x macrophage fusion hybrids acquire increased melanogenesis and metastatic potential: altered N-glycosylation as an underlying mechanism

BACKGROUND AND OBJECTIVE: The aim of this study was to assess CO2 laser ability to eliminate bacteria from titanium implant surfaces. The changes of the surface structure, the rise in temperature, and the damage of connective tissue cells after laser irradiation were also considered. STUDY DESIGN/MATERIALS AND METHODS: Streptococcus sanguis and Porphyromonas gingivalis on titanium discs were irradiated by an expanded beam of CO2 laser. Surface alteration was observed by a light, and a scanning electron, microscope. Temperature was measured with a thermograph. Damage of fibroblastic (L-929) and osteoblastic (MC3T3-E1) cells outside the irradiation spot and adhesion of the cells to the irradiated area were also estimated. RESULTS: All the organisms (10(8)) of S. sanguis and P. gingivalis were killed by the irradiation at 286 J/cm2 and 245 J/cm2, respectively. Furthermore, laser irradiation did not cause surface alteration, rise of temperature, serious damage of connective tissue cells located outside the irradiation spot, or inhibition of cell adhesion to the irradiated area. CONCLUSION: CO2 laser irradiation with expanded beam may be useful in removing bacterial contaminants from implant surface.