| Purpose: This study used low level laser to irradiate the orthodontic tooth,in order to investigate the effects of low level laser irradiation of different energy density on the degree of pain in orthodontic patients and speed of tooth movement,to provide clinical basis for determining the suitable irradiation energy density.Method: A total of 24 patients were treated with AO self-ligating brackets,aged between 18 and 29 years old.The maxillary first premolars were removed,used micro screw anchorages to retract the anterior teeth.The right and left sides in the maxillary of each patient were randomly divided into control group(non-irradiation after forcing,n=16),experimental group 1(irradiated 20 s after forcing,energy density 15.92J/cm2,n=16)and experimental group 2(irradiated 40 s after forcing,energy density 31.85J/cm2,n=16).The research started at the stage of pulling maxillary canine to distal side after alignment and leveling.The wire was 0.018 x 0.025 stainless steel wire.Micro-screws were used as the anchorage on both sides of the maxillary molars area.Using nickel titanium tension springs to pull canines to the distal side with the power of 150 g.After forcing,low level laser irradiation was applied by placing the optical tip from neck,middle of roots to root apexes of mucosa,located in the area of experimental maxillary canines both lip and lingual at 0,3,7 and 14 days.The control group treated with simulated irradiation(irradiation without power,blind method).Reloading the force and guaranting the force value was 150 g every 4 weeks.Using low level laser to irradiate the maxillary canine teeth after subsequent visit.The research lasted 4 months.To measure the amount of canines movement,plaster models were made at the begin and the end of the study.Measuring the distances between canine cusp and the mesial buccal cusp of first molar respectively.The differences were the distance of the canine moved to the distance.All patients adopt the way of questionnaire to record pain reaction at the first 7 days after forced to the canines,the orthodontic pain degrees were recorded according to the international general VAS pain rating scale.Informing patients not to take painkillersduring treatment.Explaning the content and request of the questionnaire in detail to patients and their parents to obtain the patient’s cooperation.1.In the experiment of tooth movement,mean distance of canines movement was experimental group 1(4.432 ± 0.571mm)> experimental group 2(3.724 ±0.320mm)> control group(3.532±0.516mm),there was statistical significance of difference between the experimental group 1 and the control group,the experimental group 2(P<0.05).The difference between the experimental group 2 and the control group was not obvious.The results indicated that low level laser irradiation(irradiated 20 s,energy density 15.92J/cm2)can accelerate tooth movement.High doses of laser irradiation can not accelerate the tooth movement.2.In the tooth pain test,the total mean of pain was control group(2.11±0.09)> experimental group 2(2.00±0.09)> experimental group 1(1.45±0.09),there was statistical significance of the mean difference between the experimental group 1 and the control group,the experimental group 2(P<0.05).There was no significant difference between the experimental group 2 and the control group(P> 0.05),which indicated that low energy laser irradiation(irradiation 20 s,energy density 15.92 J / cm 2)could relieve the pain of orthodontic tooth.High doses of laser irradiation could not relieve the pain of orthodontic teeth.Conclusion: Low level laser irridation can accelerate the orthodontic teeth movement and reduce the pain of stressed teeth,but the appropriate irradiation dose is needed.Too high energy density is invalid to accelerate orthodontic teeth movement or reduce the pain of the forced teeth. |
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