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ORIGINAL ARTICLES
CO2 laser oral soft tissue welding: an in vitro study Sajee Sattayut 1, Pitinuch Nakkyo 2, Puntiwa Phusrinuan 3, Thanyaporn Sangiamsak 4, Ratchanee Phiolueang 5
1: Lasers in Dentistry Research Group, Khon Kaen University, Thailand 2: Prasat Hospital, Prasat, Surin, Thailand 3: Payathai Sriracha Hospital, Chonburi, Thailand 4: Kantarawichai Hospital, Mahasarakham, Thailand 5: Thatoom Hospital, Surin, Thailand
Background and aim: Although there are some studies reporting the benefits of using laser to improve wound closure, there were a few studies in a model of oral mucosa. The aim of this in vitro study was to compare immediate tensile strength of the wound closure between suture alone and suture combined with CO2 laser welding. Materials and methods: The study was conducted in 40 samples of the tissue blocks from ventral sides of pig tongues. A 20 mm-length and 5 mm-depth incision was made in each sample. The samples were randomly allocated into 2 groups namely: the control group and the experimental group. The samples of the control group were sutured with 3- stitch of 4-0 black silk. The samples of the experimental group were irradiated with CO2 laser (ultrapulse mode, 800 Watt peak power, 10 Hz, 0.2 ms pulse duration and 2,262.62 J/cm2 energy density) before sutured. The immediate tensile strength of the wound was measured by using customized tensiometer under stereomicroscope. Results: The median of tensile strength of the control group and the experimental group were 30.40 g/cm2 and 40.50 g/cm2, respectively. There was no statistically significant difference between the groups (P value = 0.58). The proportions of the samples without wound dehiscence at the maximum limit of the tensiometer (120 g/cm2) were 0.15 (3/20) in the control group and 0.35 (7/20) in the experimental group. Conclusion: The CO2 laser welding used in this study failed to show a greater immediate tensile strength but had a higher proportion of the wound without dehiscence at the 120 g/cm2 tensile strength by comparison with the suture alone. Key words: Oral mucosa • Oral surgery • Tensile strength • Tensiometer • Suture • Wound closure
Introduction There are a number of in vitro and in vivo studies in a variety of tissues such as nerve, vessel, skin, gastrointestinal and urinary mucosa reporting the use of laser for wound approximation and closure 1-6). The results showed benefits of improving immediate tensile strength and fluid tight seal. The laser-assisted wound approximation can be divided into 2 techniques namely: laser tissue welding which is direct application of Addressee for Correspondence: Associate Professor Sajee Sattayut Lasers in Dentistry Research Group and Oral Surgery Department, Faculty of Dentistry, Khon Kaen University, Khon Kaen, 40002, Thailand Tel: +66 81 544 2460 E-mail: [email protected] ©2013 JMLL, Tokyo, Japan
precise laser energy to the site to be welded and laser tissue soldering which is using a substrate such as protein-based fluid and dye to absorb the laser energy 7). Regarding the study in oral mucosa, there was an in vivo study by Greene et al 8) comparing immediate tensile strength between laser welding and suture of incisions on the pig tongues. Although this study showed that CO2 laser welding could produce equivalent or stronger tensile strength than the suture, the immediate tensile strength which was an expected result for promotion of healing in the laser welding group was less than the suture group. Owing to this potential area, it was worth exploring the benefit of combined laser tissue welding and suture to improve Received Date: December 18th, 2012 Accepted Date: January 26th, 2013
Laser Therapy 22.1: 11-15
11
ORIGINAL ARTICLES
available at www.jstage.jst.go.jp/browse/islsm
A double blind in vitro experiment was conducted in 40 tissue blocks. The specimens were randomly allocated into 2 groups; 20 samples each group, namely the suture alone as the control and the combined CO2 laser welding and suture as the experimental group.
ficed. Then the specimens were left until reached the room temperature. They were obtained in the experiment and fixed in 24 hours as this can avoid tissue histological autolysis or necrosis 9,10). The ventral side of the pig tongue was prepared in a size of 3 x 5 cm block (figure 1A). A 5 mm depth and 20 mm length incision was made in the middle of the surface of the tissue block (figure 1B) by using the customized scalpel with depth- stopper and incisionslot (figure 1C). The actual depth and length of incision of each tissue block was measured. The means of incisional depth and length were 4.1 mm (SD = 0.2) and 10.34 (SD = 0.3 mm), respectively.
Sample preparation
CO2 laser tissue welding
Specimens were prepared by the researcher, not involving the other methods of experiment, using fresh, dead tissue from pig tongues. The tissues were stored at 4°C immediately after the animals were sacri-
The specification of laser machine used in this in vitro study was 10.6 micron CO2 laser (model SNJ-1000, SNJ Co., Ltd) with 0.3 mm diameter of spot size. The setting up was in ultrapulse mode; 800 Watt peak power/
the immediate tensile strength in oral mucosa. The aim of this study was to compare immediate tensile strength of the wounds in the tissue blocks repaired by suture alone with the combined CO2 laser welding and suture.
Materials and methods
Fig. 1: Sample preparation
Fig. 1A: Tissue block prepared from the ventral side of the tongue
Fig. 1B: Making an incision on the surface of tissue block
Fig. 1C: A scalpel with a 5 mm depth-stopper and a rule with a 20 mm incision-slot 12
Sattayut Sajee et al.
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ORIGINAL ARTICLES
Fig. 2: The methods of experiment
Fig. 2A: The tissue block with incision wound
Fig. 2B: CO2 laser irradiating to the margins and surfaces of the wound
Fig. 2C: The specimens of both groups were sutured with 4-0 black silk. Fig. 3: The customized tensiometer The specimen was placed on a platform and gripped by the mounts. The movable mount (M) with the connector (C) of which ending rod pressing on an electronic meter (E) used for providing tension to the specimen and recoding the tensile strength.
Fig. 4b Fig. 4a
CO2 laser oral soft tissue welding: An in vitro study
13
ORIGINAL ARTICLES 0.2 msec pulse duration/10Hz. The energy density measured by the powermeter from the dealer company (Medical Laser Thailand Co., Ltd) was 2,262.62J/cm2 per pulse. This regime was tested in a pilot study resulting no shrinkage and ablative effect of the margins of the specimens.
Methods The prepared tissue blocks were randomly allocated into 2 groups (figure 2A). The experimental group was irradiated by CO2 laser to the raw surfaces and the margins at the rate of 1 cm per second (figure 2B). Then 3 stitches of 4-0 black silk sutures were equivalently placed by the researcher who was blinded the groups of study (figure 2C). The control group was undertaken the same procedures apart from using the inactive CO2 laser which was the mutual setting of CO2 laser with a laser-beam blocker in the laser probe.
Measurement The measurement of the breaking strength of wound by using tensiometer 2,11) was conducted. All specimens then placed in the customized tensiometer. This was mainly composed of a platform for tissue block, a movable mounting for stretching the margins of the sample and an electronic meter (figure 3). There was a connecting rod from the movable mount to the electronic meter. The end of the rod pressing on an electronic meter was designed to be a size of 1 cm 2 . Therefore, the tension was able to be measured in a unit of g/cm2. The maximum tension of this apparatus was 120 g/cm2. In this study, an increasing of tension was controlled by the length of movement of the movable mounting at the rate of 0.5 mm/min. During increasing the tension to the sample, the separation of the wound margins was inspected under a stereomicroscope (figure 4A). The tension was recorded immediately when the dehiscence of the margins was detected (figure 4B). The measurement was undertaken by the other researcher not involving in the irradiation method.
available at www.jstage.jst.go.jp/browse/islsm
Statistical analysis The tensile strengths between the groups were compared using t-test at the significant level of 0.05 P valve. In case the data was not normal distribution, the non- parametric statistics; Mann-Whitney U test, was used.
Results Some samples in both groups had no separation of the wound margins at the maximum limit of the tensiometer (120 g/cm2). The proportions of non-dehiscence samples at 120 g/cm2 tension were 3/20 (0.15) in the suture alone group and 7/20 (0.35) in the combined CO2 laser welding and suture. The main results, the immediate tensile strengths of both groups, were not normal distribution. The calculation using Shapiro-Wilk test showed P value at 0.53. Therefore, the non-parametric statistics were applied. The median of the suture alone group from 17 samples was 30.40 g/cm 2 while the median of the combined CO2 laser welding and suture from 13 samples was 40.50 g/cm2 (table 1). There was no statistically significant difference between the groups by analyzing with Mann-Whitney U test (P value = 0.58).
Discussion Even though, there was no statistically significant difference of the immediate tensile strength between the suture alone and the combined CO2 laser welding, the proportion of the samples without wound dehiscence at 120 g/cm2 tension of the experimental group; combined CO2 laser and suture, was twice times higher than the control group; suture alone. Therefore, it tended to show that combined CO 2 laser welding and suture may able to increase an immediate tensile strength in the samples of simulating incision-wound in oral mucosa. It was different from the study of Greene et al 8) in that the average of tensile strength in 1 hour
Table 1: The Medians of immediate tensile strength and the 25th and 75th percentiles by the groups Groups Suture alone CO2 laser welding + suture
14
Tensile strength (g/cm2) Median 30.40 40.50
25th percentile 16.80 21.40
75th percentile 74.60 83.0
Sattayut Sajee et al.
available at www.jstage.jst.go.jp/browse/islsm
of the CO2 laser welding (3.30 lb) was less than the suture group (3.40 lb). This can be explained by the different settings of CO2 laser. This study used the ultrapulse mode with the calibrated parameter showing no shrinkage of the wound margins while the other used repeated pulse mode producing some photoablation. In the previous studies 8, 12), they found that CO2 laser in repeated pulse mode provided some lateral heat damage of the tissue. Additionally, there was a study showed that the controlled temperature around 55°C; below the level of coagulation at 60°C, was significant for the success of welding of urinary bladder 3). Regarding the clinical application, this tissue welding technique using CO 2 can be applied for enhancing an immediate tensile strength of intraoral
ORIGINAL ARTICLES suture to promote wound healing. The CO2 laser welding is not able to be used solely without suture. As far as sutureless closure of oral soft tissue concerned, the tissue soldering with protein media 13,14) is suggested to be a further study.
Conclusion The combined CO2 laser welding at ultrapulse mode and suture had no statistically significant difference in immediate tensile strength of the wound closure in oral soft tissue blocks by comparison with the suture alone but had the higher proportion of the wounds without dehiscence at the 120 g/cm2 tensile strength.
References 1: Gulsoy M, Dereli Z, Tabakoglu HO, Bozkulak O (2006): Closure of skin incisions by 980-nm diode laser welding. Lasers in Medical Science, 21:5~10. 2: Fried NM, Walsh JT, Jr (2000) Laser skin welding: in vivo tensile strength and wound healing results. Lasers in Surgery and Medicine, 27:55~65. 3: Lobel B, Eyal O, Kariv N, Katzir A (2000): Temperature controlled CO2 laser welding of soft tissues: urinary bladder welding in different animal models (rats, rabbits, and cats). Lasers in Surgery and Medicine, 26:4~12. 4: Menovsky T (2000): CO2 and Nd:YAG laser-assisted nerve repair: a study of bonding strength and thermal damage. Acta Chirurgiae Plasticae, 42:16~22. 5: Poppas DP, Rucker GB, Scherr DS (2000): Laser Tissue Welding - Poised for the New Millenium. Surgery Technology International, 9:33~41. 6: Bass LS, Treat MR (1995): Laser tissue welding: a comprehensive review of current and future clinical applications. Lasers in Surgery and Medicine, 17:315~349. 7: Chivers RA (2000): In vitro tissue welding using albumin solder: bond strengths and bonding temperatures. International Journal of Adhesion and Adhesive, 20:179~187. 8: Greene CH, Debias DA, Henderson MJ, Fair-Covely R, Dorf B, Radin AL (1994): Healing of incisions in the tongue: a comparison of results with milliwatt
CO2 laser oral soft tissue welding: An in vitro study
carbon dioxide laser tissue welding versus suture repair. Annals of Otology, Rhinology and Laryngology, 103:964~974. 9: Sattayut S, Bradley P (2003): A comparative study of the central vaporization with peripheral coagulation of Nd YAG laser. International Congress Series, 1248:371~376. 10: Berman B, Chen VL, France DS, Dotz WI, Petroni G (1983): Anatomical mapping of epidermal Langerhans cell densities in adults. British Journal of Dermatology, 109:553~558. 11: Sanders DL, Reinisch L (2000): Wound healing and collagen thermal damage in 7.5-microsec pulsed CO2 laser skin incisions. Lasers in Surgery and Medicine, 26:22~32. 12: Paes-Junior TJA (2001): Clinical comparison between conventional suture and vaporization with carbon dioxide laser in rat’s skin. Journal of Clinical Laser Medicine Surgery, 19:319~324. 13: Wolf-de Jonge IC, Heger M, van Marle J, Balm R, Beek JF (2008): Suture-free laser-assisted vessel repair using CO2 laser and liquid albumin solder. Journal of Biomedicine Optics, 13:044032. 14: Maitz PK, Trickett RI, Dekker P, Tos P, Dawes JM, Piper JA (1999): Sutureless microvascular anastomoses by a biodegradable laser-activated solid protein solder. Plastic and Reconstructive Surgery, 104:1726~1731.
15
ORIGINAL ARTICLES
CO2 laser oral soft tissue welding: an in vitro study Sajee Sattayut 1, Pitinuch Nakkyo 2, Puntiwa Phusrinuan 3, Thanyaporn Sangiamsak 4, Ratchanee Phiolueang 5
1: Lasers in Dentistry Research Group, Khon Kaen University, Thailand 2: Prasat Hospital, Prasat, Surin, Thailand 3: Payathai Sriracha Hospital, Chonburi, Thailand 4: Kantarawichai Hospital, Mahasarakham, Thailand 5: Thatoom Hospital, Surin, Thailand
Background and aim: Although there are some studies reporting the benefits of using laser to improve wound closure, there were a few studies in a model of oral mucosa. The aim of this in vitro study was to compare immediate tensile strength of the wound closure between suture alone and suture combined with CO2 laser welding. Materials and methods: The study was conducted in 40 samples of the tissue blocks from ventral sides of pig tongues. A 20 mm-length and 5 mm-depth incision was made in each sample. The samples were randomly allocated into 2 groups namely: the control group and the experimental group. The samples of the control group were sutured with 3- stitch of 4-0 black silk. The samples of the experimental group were irradiated with CO2 laser (ultrapulse mode, 800 Watt peak power, 10 Hz, 0.2 ms pulse duration and 2,262.62 J/cm2 energy density) before sutured. The immediate tensile strength of the wound was measured by using customized tensiometer under stereomicroscope. Results: The median of tensile strength of the control group and the experimental group were 30.40 g/cm2 and 40.50 g/cm2, respectively. There was no statistically significant difference between the groups (P value = 0.58). The proportions of the samples without wound dehiscence at the maximum limit of the tensiometer (120 g/cm2) were 0.15 (3/20) in the control group and 0.35 (7/20) in the experimental group. Conclusion: The CO2 laser welding used in this study failed to show a greater immediate tensile strength but had a higher proportion of the wound without dehiscence at the 120 g/cm2 tensile strength by comparison with the suture alone. Key words: Oral mucosa • Oral surgery • Tensile strength • Tensiometer • Suture • Wound closure
Introduction There are a number of in vitro and in vivo studies in a variety of tissues such as nerve, vessel, skin, gastrointestinal and urinary mucosa reporting the use of laser for wound approximation and closure 1-6). The results showed benefits of improving immediate tensile strength and fluid tight seal. The laser-assisted wound approximation can be divided into 2 techniques namely: laser tissue welding which is direct application of Addressee for Correspondence: Associate Professor Sajee Sattayut Lasers in Dentistry Research Group and Oral Surgery Department, Faculty of Dentistry, Khon Kaen University, Khon Kaen, 40002, Thailand Tel: +66 81 544 2460 E-mail: [email protected] ©2013 JMLL, Tokyo, Japan
precise laser energy to the site to be welded and laser tissue soldering which is using a substrate such as protein-based fluid and dye to absorb the laser energy 7). Regarding the study in oral mucosa, there was an in vivo study by Greene et al 8) comparing immediate tensile strength between laser welding and suture of incisions on the pig tongues. Although this study showed that CO2 laser welding could produce equivalent or stronger tensile strength than the suture, the immediate tensile strength which was an expected result for promotion of healing in the laser welding group was less than the suture group. Owing to this potential area, it was worth exploring the benefit of combined laser tissue welding and suture to improve Received Date: December 18th, 2012 Accepted Date: January 26th, 2013
Laser Therapy 22.1: 11-15
11
ORIGINAL ARTICLES
available at www.jstage.jst.go.jp/browse/islsm
A double blind in vitro experiment was conducted in 40 tissue blocks. The specimens were randomly allocated into 2 groups; 20 samples each group, namely the suture alone as the control and the combined CO2 laser welding and suture as the experimental group.
ficed. Then the specimens were left until reached the room temperature. They were obtained in the experiment and fixed in 24 hours as this can avoid tissue histological autolysis or necrosis 9,10). The ventral side of the pig tongue was prepared in a size of 3 x 5 cm block (figure 1A). A 5 mm depth and 20 mm length incision was made in the middle of the surface of the tissue block (figure 1B) by using the customized scalpel with depth- stopper and incisionslot (figure 1C). The actual depth and length of incision of each tissue block was measured. The means of incisional depth and length were 4.1 mm (SD = 0.2) and 10.34 (SD = 0.3 mm), respectively.
Sample preparation
CO2 laser tissue welding
Specimens were prepared by the researcher, not involving the other methods of experiment, using fresh, dead tissue from pig tongues. The tissues were stored at 4°C immediately after the animals were sacri-
The specification of laser machine used in this in vitro study was 10.6 micron CO2 laser (model SNJ-1000, SNJ Co., Ltd) with 0.3 mm diameter of spot size. The setting up was in ultrapulse mode; 800 Watt peak power/
the immediate tensile strength in oral mucosa. The aim of this study was to compare immediate tensile strength of the wounds in the tissue blocks repaired by suture alone with the combined CO2 laser welding and suture.
Materials and methods
Fig. 1: Sample preparation
Fig. 1A: Tissue block prepared from the ventral side of the tongue
Fig. 1B: Making an incision on the surface of tissue block
Fig. 1C: A scalpel with a 5 mm depth-stopper and a rule with a 20 mm incision-slot 12
Sattayut Sajee et al.
available at www.jstage.jst.go.jp/browse/islsm
ORIGINAL ARTICLES
Fig. 2: The methods of experiment
Fig. 2A: The tissue block with incision wound
Fig. 2B: CO2 laser irradiating to the margins and surfaces of the wound
Fig. 2C: The specimens of both groups were sutured with 4-0 black silk. Fig. 3: The customized tensiometer The specimen was placed on a platform and gripped by the mounts. The movable mount (M) with the connector (C) of which ending rod pressing on an electronic meter (E) used for providing tension to the specimen and recoding the tensile strength.
Fig. 4b Fig. 4a
CO2 laser oral soft tissue welding: An in vitro study
13
ORIGINAL ARTICLES 0.2 msec pulse duration/10Hz. The energy density measured by the powermeter from the dealer company (Medical Laser Thailand Co., Ltd) was 2,262.62J/cm2 per pulse. This regime was tested in a pilot study resulting no shrinkage and ablative effect of the margins of the specimens.
Methods The prepared tissue blocks were randomly allocated into 2 groups (figure 2A). The experimental group was irradiated by CO2 laser to the raw surfaces and the margins at the rate of 1 cm per second (figure 2B). Then 3 stitches of 4-0 black silk sutures were equivalently placed by the researcher who was blinded the groups of study (figure 2C). The control group was undertaken the same procedures apart from using the inactive CO2 laser which was the mutual setting of CO2 laser with a laser-beam blocker in the laser probe.
Measurement The measurement of the breaking strength of wound by using tensiometer 2,11) was conducted. All specimens then placed in the customized tensiometer. This was mainly composed of a platform for tissue block, a movable mounting for stretching the margins of the sample and an electronic meter (figure 3). There was a connecting rod from the movable mount to the electronic meter. The end of the rod pressing on an electronic meter was designed to be a size of 1 cm 2 . Therefore, the tension was able to be measured in a unit of g/cm2. The maximum tension of this apparatus was 120 g/cm2. In this study, an increasing of tension was controlled by the length of movement of the movable mounting at the rate of 0.5 mm/min. During increasing the tension to the sample, the separation of the wound margins was inspected under a stereomicroscope (figure 4A). The tension was recorded immediately when the dehiscence of the margins was detected (figure 4B). The measurement was undertaken by the other researcher not involving in the irradiation method.
available at www.jstage.jst.go.jp/browse/islsm
Statistical analysis The tensile strengths between the groups were compared using t-test at the significant level of 0.05 P valve. In case the data was not normal distribution, the non- parametric statistics; Mann-Whitney U test, was used.
Results Some samples in both groups had no separation of the wound margins at the maximum limit of the tensiometer (120 g/cm2). The proportions of non-dehiscence samples at 120 g/cm2 tension were 3/20 (0.15) in the suture alone group and 7/20 (0.35) in the combined CO2 laser welding and suture. The main results, the immediate tensile strengths of both groups, were not normal distribution. The calculation using Shapiro-Wilk test showed P value at 0.53. Therefore, the non-parametric statistics were applied. The median of the suture alone group from 17 samples was 30.40 g/cm 2 while the median of the combined CO2 laser welding and suture from 13 samples was 40.50 g/cm2 (table 1). There was no statistically significant difference between the groups by analyzing with Mann-Whitney U test (P value = 0.58).
Discussion Even though, there was no statistically significant difference of the immediate tensile strength between the suture alone and the combined CO2 laser welding, the proportion of the samples without wound dehiscence at 120 g/cm2 tension of the experimental group; combined CO2 laser and suture, was twice times higher than the control group; suture alone. Therefore, it tended to show that combined CO 2 laser welding and suture may able to increase an immediate tensile strength in the samples of simulating incision-wound in oral mucosa. It was different from the study of Greene et al 8) in that the average of tensile strength in 1 hour
Table 1: The Medians of immediate tensile strength and the 25th and 75th percentiles by the groups Groups Suture alone CO2 laser welding + suture
14
Tensile strength (g/cm2) Median 30.40 40.50
25th percentile 16.80 21.40
75th percentile 74.60 83.0
Sattayut Sajee et al.
available at www.jstage.jst.go.jp/browse/islsm
of the CO2 laser welding (3.30 lb) was less than the suture group (3.40 lb). This can be explained by the different settings of CO2 laser. This study used the ultrapulse mode with the calibrated parameter showing no shrinkage of the wound margins while the other used repeated pulse mode producing some photoablation. In the previous studies 8, 12), they found that CO2 laser in repeated pulse mode provided some lateral heat damage of the tissue. Additionally, there was a study showed that the controlled temperature around 55°C; below the level of coagulation at 60°C, was significant for the success of welding of urinary bladder 3). Regarding the clinical application, this tissue welding technique using CO 2 can be applied for enhancing an immediate tensile strength of intraoral
ORIGINAL ARTICLES suture to promote wound healing. The CO2 laser welding is not able to be used solely without suture. As far as sutureless closure of oral soft tissue concerned, the tissue soldering with protein media 13,14) is suggested to be a further study.
Conclusion The combined CO2 laser welding at ultrapulse mode and suture had no statistically significant difference in immediate tensile strength of the wound closure in oral soft tissue blocks by comparison with the suture alone but had the higher proportion of the wounds without dehiscence at the 120 g/cm2 tensile strength.
References 1: Gulsoy M, Dereli Z, Tabakoglu HO, Bozkulak O (2006): Closure of skin incisions by 980-nm diode laser welding. Lasers in Medical Science, 21:5~10. 2: Fried NM, Walsh JT, Jr (2000) Laser skin welding: in vivo tensile strength and wound healing results. Lasers in Surgery and Medicine, 27:55~65. 3: Lobel B, Eyal O, Kariv N, Katzir A (2000): Temperature controlled CO2 laser welding of soft tissues: urinary bladder welding in different animal models (rats, rabbits, and cats). Lasers in Surgery and Medicine, 26:4~12. 4: Menovsky T (2000): CO2 and Nd:YAG laser-assisted nerve repair: a study of bonding strength and thermal damage. Acta Chirurgiae Plasticae, 42:16~22. 5: Poppas DP, Rucker GB, Scherr DS (2000): Laser Tissue Welding - Poised for the New Millenium. Surgery Technology International, 9:33~41. 6: Bass LS, Treat MR (1995): Laser tissue welding: a comprehensive review of current and future clinical applications. Lasers in Surgery and Medicine, 17:315~349. 7: Chivers RA (2000): In vitro tissue welding using albumin solder: bond strengths and bonding temperatures. International Journal of Adhesion and Adhesive, 20:179~187. 8: Greene CH, Debias DA, Henderson MJ, Fair-Covely R, Dorf B, Radin AL (1994): Healing of incisions in the tongue: a comparison of results with milliwatt
CO2 laser oral soft tissue welding: An in vitro study
carbon dioxide laser tissue welding versus suture repair. Annals of Otology, Rhinology and Laryngology, 103:964~974. 9: Sattayut S, Bradley P (2003): A comparative study of the central vaporization with peripheral coagulation of Nd YAG laser. International Congress Series, 1248:371~376. 10: Berman B, Chen VL, France DS, Dotz WI, Petroni G (1983): Anatomical mapping of epidermal Langerhans cell densities in adults. British Journal of Dermatology, 109:553~558. 11: Sanders DL, Reinisch L (2000): Wound healing and collagen thermal damage in 7.5-microsec pulsed CO2 laser skin incisions. Lasers in Surgery and Medicine, 26:22~32. 12: Paes-Junior TJA (2001): Clinical comparison between conventional suture and vaporization with carbon dioxide laser in rat’s skin. Journal of Clinical Laser Medicine Surgery, 19:319~324. 13: Wolf-de Jonge IC, Heger M, van Marle J, Balm R, Beek JF (2008): Suture-free laser-assisted vessel repair using CO2 laser and liquid albumin solder. Journal of Biomedicine Optics, 13:044032. 14: Maitz PK, Trickett RI, Dekker P, Tos P, Dawes JM, Piper JA (1999): Sutureless microvascular anastomoses by a biodegradable laser-activated solid protein solder. Plastic and Reconstructive Surgery, 104:1726~1731.
15
