| Dentinal hypersensitivity is a common clinical Stomatologic symptom characterized by caloric stimulation or occlusal discomfort.The dentinal tubule exposure caused by attrition is one of the main nosogenesis of dentinal hypersensitivity.The level of tooth attrition and sensitivity are two chief considerations during the treatment of dentinal hypersensitivity.Mild to moderate dentinal hypersensitivity is general treated by drug desensitization,while the patients who have severe dentin sensitivity or excessive damage of dental tissue,the tooth filing and crown restoration could be used for therapy.The former treatment has a deficiency of poor long-term efficacy,and the latter one need to damage the tooth tissue,therefore,few patients can accept that.If the symptoms have severely affected the living quality of patients,and all treatments have shown no effect,the root canal treatment must be considered.Since the laser treatment has been used for the therapy of dentinal hypersensitivity,many of the oral clinicians and scholars believe that it is likely to be an ideal method for desensitization.At present,various kinds of lasers are widely used in clinic to treat dentinal hypersensitivity,including Nd:YAG laser,C02 laser,He-Ne laser,CaAlAs semiconductor laser,Er:YAG laser,Er,Cr:YSGG laser,etc.In particular,Er:YAG laser has unique thermal effects,light effects,and biological effects that are determined by its wavelengths,making it a preferred method compared with the traditional method in many therapeutic projects.Therefore,the Er:YAG laser used in the field of oral therapy has been accepted by more and more dentists and patients.The Er:YAG laser treatment applied on dentinal hypersensitivity mainly utilizes the thermal effect of the laser on the sensitive parts of the teeth,so that the exposed dentin instantly melts to seal the dentin tubules,concequently preventing the liquid flow in the dentin tubules and blocking the external stimulation to the pulp nerve.The clinical application of Er:YAG laser in the treatment of dentinal hypersensitivity has been in full swing,and it is believed that the Er:YAG laser parameters is important factors during therapy that influence the curative effects.However,until now,the comparison between different parameters is less studied at home and abroad.There is no consensus on how to calibrate the treatment parameters,and the relationship between the treatment parameters and the curative effect is unclear.Inaddition,the study of laser treatment for the attrition-induced dentinal hypersensitivity is less.Our research group is applying the Er:YAG laser to treat dentinal hypersensitivity while actively study on the parameters.This study is aimed to explore the application range of irradiation distance,energy and time of Er:YAG laser while treating the dentinal hypersensitivity in vitro.At the same time,the optimal parameters were selected and verified invivo.The findings could provide theoretical and experimental evidences from basic to clinic and from in vitro to in vivo for the clinical application of Er:YAG laser to treat dentinal hypersensitivity caused by attrition.The study is divided into two parts,including:Part one:A vitro study of the parameters of Er:YAG in the treatment attrition-induced dentinal hypersensitivity.Firstly,applying the dentin morphological analysis by SEM on the dentinal hypersensitivity model in vitro.Analyzing the scanning image to observe the exposed area and sealing rate of dentinal tubules,and then we find the suitable irradiation distance for R02 handpiece is 3cm to 4cm and 2cm to 4cm for R04 handpiece.The appropriate irradiation energy for these two handpieces is 0.4W to 0.6W,and the suitable irradiation time is irradiated 20s/cm~2.Than,according to the irradiation distance,energy and time range obtained from the previous experiment,15 groups of irradiation parameters were cross-assembled.Through observation of the cross-sectional and longitudinal section morphology of dentinal tubules by SEM,analyzing the exposed areas and sealing rate of dentinal tubules by scanning images,performing morphological analysis of the cross section of dentinal tubules after erosion,and comparing dentinal tubules exposed area with sealing rate by analyzing the scanning images,we found that it is the optimal condition when R02 handpiece irradiated with 0.5 W at 3 cm,while R14 with 0.5W and 0.6W at 3cm,and the most suitable parameter is irradiated 20s/1cm~2.This group of parameters can seal dentinal tubules best and resist the erosion and attrition while preparing for subsequent experiments.Part two:Clinical trials of the Er:YAG laser in the treatment of attrition induced dentinal hypersensitivity.In this part of the experiment,we analyzed the curative effect of different therapies using three groups of parameters selected in the first part of the experiment,in order to study the differences of curative effect when treating dentinal hypersensitivity among patients with different degree of attrition.According to the subjective pain score scale of VAS,the Er laser parameters selected in the first part of the study can effectively treat dentinal hypersensitivity,and the immediate effect is good.The maximum curative effect is obtained in one week after therapy,then the curative effect is gradually weakened.The dentinal tubules are still effectively sealed 6 months after the therapy.Innovations1.Performing the comprehensive and integrated analysis of the Er:YAG laser parameters,energy,time and distance on the effects of closing of dentin tubules;2.Establishing the vitro attrition-induces dentinal hypersensitivity model and selecting the best Er:YAG laer parameter combinations that could well closing the dentinal tubules;3.Combinating the experimental studies and clinical trials to effectively verify the Er:YAG laser treatment effects on the attrition-induced dentinal hypersensitivity. |
