Effectiveness Of The Er:YAG Laser By Photon-induced Photoacoustic Streaming(PIPS) As An Activation Method In Root Canal Irrigation Of Primary Teeth,in Vitro And In Vivo

Part One Efficacy of the Er:YAG laser by photon-induced photoacoustic streaming(PIPS)on smear layer removal in apical thirds of the primary tooth root canalsObjective: To observe the efficacy of Er:YAG laser by photon-induced photoacoustic streaming(PIPS)on smear layer removal in apical thirds of the primary tooth root canals.Methods:20 extracted primary incisors and 20 extracted primary molars were collected.40 primary teeth were randomly divided into 4 groups according to final irrigation techniques and tooth positions: primary incisor through PIPS(20m J 15 Hz 0.3W)(group A),primary molars through PIPS(20m J 15 Hz 0.3W)(group B),primary incisor through needle irrigation(group C),primary molars through needle irrigation(group D).After the root canal preparation and final irrigation,the teeth were split longitudinal into 2 parts and examined by scanning electron microscopy to compare the efficacy on smear layer removal in apical thirds of the root canals.Results:The group A with the best score was 70%,followed by the group B with 60%,which was no statistical difference between them(P>0.05),while the group C and the group D accounted for the higher proportion in poorer scores.In both primary incisors and molars,the efficacy of PIPS as final irrigation on the removal of the smear layer in apical thirds of the primary tooth root canals was better than that of irrigation needle,and the difference was statistically significant(P<0.05).Conclusions:The Er:YAG laser by PIPS-activated irrigation is more effective in the removal of the smear layer in apical thirds of the primary tooth root canals,which is better than that of needle irrigation.Part Two Evaluation of Er:YAG laser by photon-induced photoacoustic streaming(PIPS)as an activation method in root canal irrigation of primary teethObjective:To observe the clinical effect of Er:YAG laser by photon-induced photoacoustic streaming(PIPS)as an activation method in root canal irrigation of primary teeth.Methods:A total of 75 teeth including 24 primary incisors and 51 primary molars in 60 children with chronic apical periodontitis were selected from the Department of Pediatric Stomatology,School and Hospital of Stomatology,Hebei Medical University from November 2018 to January2019.75 teeth were randomly divided into two groups: group A(n=38)and group B(n=37).During root canal therapy,the root canal was irrigated with PIPS(group A)or 1% Na Cl O irrigation needle(group B)as the final irrigation.Clinical and radiographic follow-up examinations were conducted at 1,6 and 12 months postoperatively,with the success rate calculated and compared.Results:There were no failures of group A at 1 and 6 months,and the success rate was 97.1% at 12 months.In group B,the success rate was 100.0%at 1 month,94.3% at 6 months,and 79.4% at 12 months.There was significant difference between PIPS group and irrigating needle group at 12 months(P<0.05).Conclusions:Er:YAG laser by PIPS-activated irrigation can be consi-dered as an effective irrigation technique in pediatric endodontics.Through one-year clinical observation,the clinical and radiographic result of PIPS are better than 1% Na Cl O irrigation needle.