Iraqi Journal of Laser

Background: Many conservative sphincter-preserving procedures had been described to be effective inhealing of anal fistula without excision or de roofing.Objective: To verify the outcome of mere photocoagulation of the fistula tract on healing of low analfistula.Materials and Methods:Using 810nm diode laser, the tracts of low anal fistulae in a cohorts of six malepatients (mean age of 32 yr) had been photocoagulated by retrograde application of laser light through anorb tip optical fiber threaded in to the tract. Swabs for culture and sensitivity testing were obtained beforeand after laser application. Patients were followed up regularly to announce fistula healing.Results:Mean laser exposure time was 6.6 min., mean operative time was 19 min., mean hospital staywas 5.9 hrs and mean fistula closure time was 7.7 days. The negative immediate post laser exposureswabs indicate that laser may have a bacteria killing power. There were no evidences of incontinence orrecurrence within the mean follow up period of 9 weeks. The feasibility of using the selected laser andaccessory was excellent. The basic laser-tissue interaction was thermal photocoagulation withoutcarbonization.Conclusions and Recommendations:Mere photocoagulation of the fistula tract may heal a low analfistula. Within the chosen parameters of laser application, there was no evidence of damage to the analsphincter. It is recommended that larger number of cases to be done to allow for proper statistical analysis. High, complicated, and recurrent cases may be included. A longer follow up period to assess intermediate and long term recurrences is recommended

Purpose: to evaluate the effect of various Nd:YAG frequency doubled laser parameters on the aciddissolution and the progression ofin vitro caries like lesions in human enamel.Materials and Methods: Human extracted caries free upper first premolar teeth were collected forthis study. The irradiated teeth were divided into two groups. The first group was irradiated withcontinuous Nd:YAG laser radiation, and the second group was irradiated with chopped Nd:YAG laserradiation. For the first group, power and exposure time were changed while for the second grouppower and number of pulses were changed. The spot diameter was kept constant for all the samples.Results: using 1.5 W and 3 seconds (exposure time), best results among the continuous group wereobtained, while in the chopped group using 1.5 W and 3 pulses gave better result. The percentreduction in lesion depth in this study was up to 26% in the continuous group, whereas in the choppedgroup was up to 44%

Four photosensitizers were used to test inhibitory effect ofHelicobacter pylori bacteria usinglow power helium: neon red laser radiation. Biopsies were collected from 176 patients andH. pylori wereisolated, identified and bacterial suspension was prepared. Samples of this suspension were mixed withvarious low concentrations of the test sensitizer. The mixture samples were exposed to different laserradiation doses. The samples were then inoculated and the inhibition zones were studied and comparedwith their analogues of control samples. The most effective sensitizer with optimum concentration andirradiation dose was determined. Statistical analysis of results was performed. The sensitizers' toluidineblue and the methylene blue with concentration of 100μg/ml were able to produce the same effect ofcomplete killing when irradiation energy density 13 J/cm2. However, thionin and crystal violet sensitizerswhen used with the same concentration and exposed to the same laser dose, showed minor inhibitoryeffect. Irradiation of bacterial samples with absence of sensitizer or sensitized samples at theconcentrations employed with out laser radiation has no effect on H. pylori viability in all of theexperiments.

Four photosensitizers were used to test inhibitory effect ofHelicobacter pylori bacteria usinglow power helium: neon red laser radiation. Biopsies were collected from 176 patients andH. pylori wereisolated, identified and bacterial suspension was prepared. Samples of this suspension were mixed withvarious low concentrations of the test sensitizer. The mixture samples were exposed to different laserradiation doses. The samples were then inoculated and the inhibition zones were studied and comparedwith their analogues of control samples. The most effective sensitizer with optimum concentration andirradiation dose was determined. Statistical analysis of results was performed. The sensitizers' toluidineblue and the methylene blue with concentration of 100μg/ml were able to produce the same effect ofcomplete killing when irradiation energy density 13 J/cm2. However, thionin and crystal violet sensitizerswhen used with the same concentration and exposed to the same laser dose, showed minor inhibitoryeffect. Irradiation of bacterial samples with absence of sensitizer or sensitized samples at theconcentrations employed with out laser radiation has no effect on H. pylori viability in all of theexperiments.