| ObjectiveC02 fractional laser technology is a new minimally invasive treatment for pathological scars.In this study,we studied the effect of two different modes(low energy,high-density,high-energy,low density)C02 mode laser treatment mode by using the scar model of The Female Red Duroc Pig(FRDP)after skin grafting to explore two different models.The mechanism of C02 fractional laser in treating scars and improving the appearance of scars,as well as the evaluation of whether the combined use of the two modes can achieve better therapeutic effect,provide the basis for choosing suitable C02 fractional laser modes for different types of scars in clinicMethodsContents of the experiment:1.Establish a scar model after skin grafting on FRDP,and explore the appearance,biological and histological characteristics of the scar model after skin grafting on FRDP.2.Two C02 fractional laser modes(shallow high density and deep low density)were used to treat scars after FRDP skin grafting.The objective data(thickness,area,elasticity,flatness,color)and histological examination of scars before and after treatment were measured.Subjective assessment scale and objective data were used to evaluate the scar model of FRDP skin grafting treated by two modes of C02 fractional laser.The curative effect of the two models was analyzed3.Two C02 fractional laser modes(shallow high density,deep low density)were used to treat scars after FRDP skin grafting.The objective data(thickness,area,elasticity,flatness,color)and histological examination of scars before and after treatment were measured.Subjective assessment scale and objective data were used to evaluate the combined mode of C02 fractional laser treatment for scar model after FRDP skin grafting.Therapeutic effect was analyzed.The difference of curative effect between the combined model and the two models was analyzedExperimental design:Model construction and experimental groupingThree-month-old FRDP was divided into left and right sides by spine.Eight full-thickness mechanical wounds of 3 cm*3 cm were performed on each side.There were two of them and 32 wounds.After excision of the whole dermis and subcutaneous tissue,the original skin graft was replanted.The scar model of FRDP skin graft was established.The successful skin graft was selected(the survival area of the skin>80%was recorded as the success of the model).The number of successful scars was counted and treated by laser for the first time six weeks after the model was established.Successful scar modeling was randomly divided into four groups:1 Control group.(2)Low-density deep-level fractional laser treatment group.The parameters of machine therapy were size 1,7%,60w,960mj/piexl(depth<1mm,108 piexl/cm2,103.6J/cm2).(3)High density shallow-level fractional laser treatment group The parameters of machine therapy were size 3,3%,60W,2800 mj/piexl(depth>2.5mm,36 piexl/cm2,100.8J/cm2).(4)Deep and shallow combined treatment group(3)The first laser treatment was performed in the group of FRDP skin graft 6 weeks after the success of scar modeling.The treatment lasted for two times,with an interval of 6 weeks.The control group received no treatmentData collection1.Subjective scoring dataAt the 18th week after modeling in the control group,the appearance of scars in each laser treatment group was subjectively assessed by Vancouver Score Scale 6 weeks after two laser treatments,and statistical data were obtained2.Objective dataBefore laser treatment,3 weeks after laser treatment,6 weeks after laser treatment,3 weeks after laser treatment,and 6 weeks after laser treatment,the changes of scar thickness,scar area,hardness,smoothness and color were observed and recorded.At the same time,tissue samples were collected,and the thickness,area,hardness,smoothness and color of scars in each group were detected by objective detection instrument.The objective measurement data of each group at each time point were counted,and the difference of curative effect of each laser treatment mode after two times was analyzed.The histological characteristics of scars were observed by pathological sections of each group,as well as the changes of various objective indicators with timeData analysisAll the numerical results of this experiment were analyzed by SPSS software The measurement data of each group were expressed as X±S.The normality test and homogeneity analysis of variance were performed for each group.The data were normal distribution and homogeneous variance was compared between the two groups by independent sample t test.The non-parametric test was used to analyze the inter-group data which did not conform to normal distribution or uneven variance Mann-Whitney U rank sum test was used to compare the data between the two groups P<0.05 was considered to have statistical significanceResults1.Scar Modeling Results after FRDP Skin GraftingThirty-two models were successfully modeled and 26 models were successfully modeled.The success rate was 81.3%.From 2 weeks after the dressing was removed to 18 weeks after the model was successfully established,the thickness and scar area of the control group did not change significantly,the hardness gradually increased,the flatness gradually decreased,and pigmentation gradually appeared.Histologically,the fibrous bundles of the scar gradually increased and disordered,and the infiltration of inflammatory cells decreased.2.The difference of curative effect between different modes of C02 fractional laser in the treatment of scar after FRDP skin grafting twice1.Subjective assessment resultsEighteen weeks after the model was established and six weeks after two laser treatments,the average Vancouver score(the smaller the value,the closer to normal skin)of each group was:control group 8.17(±1.47),shallow high density group 7.67(±0.81),deep low density group 5.14(±1.07),and combined treatment group 4.86(±0.69).There was significant difference between group 4 and group 1.Further analysis showed that the mean score of color and softness in group 4 was significantly lower than that in group 1(P<0.05).2.Measurement results of objective data(1)Scar thickness:Deep-seated low-density therapy and combination therapy lead to temporary,long-lasting tissue edema.After 18 weeks/6 weeks of laser treatment,the temporary edema caused by laser disappeared.The thickness of scar in each group was:1)0.327(+0.061 cm)in the control group,0.339(+0.060 cm)in the shallow high density group,0.338(+0.056 cm)in the deep low density group and 0.318(+0.056 cm)in the combined treatment group.There was no significant difference between the laser treatment group and the control group(P>0.05).(2)Scar area:In the process of scar maturation after FRDP skin grafting,skin area contracture will occur first and then stabilize.Eighteen weeks after model establishment and six weeks after laser treatment,the average scar area of each group was:control group 683.3(±119.3 mm),shallow high density group 697.5(±189.9 mm),deep low density group 769.4(±160.8 mm)and combined treatment group 796.5(±159.8 mm).(3)The average area of group 1 was increased by 86.1 mm_and that of group 4 was increased by 113.2 mm_compared with group 1(P<0.05).(3)There was no statistical difference between groups,and(2)there was no statistical difference between groups(P>0.05).(3)Scar elasticity:18 weeks after modeling/6 weeks after laser treatment twice,the average value of scar elasticity index R2(R2 approaching 1 represents better elasticity)in each group was as follows:control group 0.573(±0.176);shallow high density group 0.593(±0.245);deep low density group 0.828(±0.182);combined treatment group 0.818(±0.165).(3)The average R2 value of the group was increased by 0.255,and(4)the average R2 value of the group was increased by 0.245,with statistical significance(P<0.05).(3)There was no statistical difference between the groups,and(2)there was no statistical difference between the groups(P>0.05)(4)Scar smoothness:Six weeks after laser treatment,the scar smoothness of deep low density group increased significantly.The average number of large skin folds(width>lmm,length>3mm)in each group was:control group 2.00(±0.89);shallow high density group 1.83(±0.75);deep low density group 0.57(±0.534);combined treatment group 0.44(±0.16).(3)The average number of large skin folds decreased by 1.33 in group 1,and 1.46 in group 4(P<0.05).There was no significant difference between groups(P>0.05).There was no significant difference between groups(P>0.05).The levelness of the combined treatment group was higher than that of the deep low density group.The number of small wrinkles(width of depression>0.5 mm,length>2 mm)in the two groups was as follows:(3)Deep low density group 2.14(±1.07)combined treatment group 0.71(±0.49).The average number of small wrinkles decreased by 1.43%and the percentage decreased by 66.8%in the deep low density group of the combined treatment group after two laser treatments(P<0.05)Pigment color:Six weeks after two laser treatments,eighteen weeks after modeling and six weeks after two laser treatments,the average melanin index(MI)of each group was:control group 815.8(±20.9);shallow high density group 810.8(±14.5);deep low density group 808.4(±16.1);combined treatment group 793.875(±10.8).(3)The average MI value of group 1 was 7.4 lower than that of group 1.The average MI value of group 4 was 21.92 lower than that of group 1(P<0.05).There was no statistical difference between groups(P>0.05).There was no statistical difference between groups(P>0.05)Histology:C02 fractional laser can make the large striated collagen bundles in scar tissue become more orderly and compact after treatment.The change area of collagen fibers basically coincides with the treatment area.The distribution of deep collagen in scar tissue under superficial high density treatment mode remains unchangedConclusionFrom the experimental results of this study,we can draw the conclusion that laser treatment has no effect on the thickness of non-hypertrophic scar in the energy range of this experiment.In the treatment of scar after skin grafting,the use of superficial and high density C02 fractional laser alone can only slightly or not improve the color of scar,while the use of deep and low density C02 laser alone can significantly reduce the shrinkage of scar area,greatly improve the color of scar,and improve the elasticity and smoothness of scar.In addition,the application of deep C02 fractional laser combined with shallow C02 fractional laser can reduce the contracture of scar area,improve the softness of scar,improve the color and luster of scar,and further improve the smoothness of scar.The results have certain guiding significance for choosing different treatment modes according to the pathological characteristics of scars,and can provide basis for formulating corresponding laser treatment strategies for different types of scars in clinic. |
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