| Objective: The accurate working length of root canal is the core link of perfecting root canal therapy that running through every step.Periapical can display the full view of teeth and the hard tissue situation of the tissue around root tip,which is widely applied as a method of measuring the working length of root canal.Therefore,it compared and analyzed the accuracy and advantages as well as d isadvantages of two periapical including paralleling technique and bisecting angle in measuring the working length of root canal so as to offer reference to clinical flexible selection of periapical radiograph.Method: Select 55 patients with ill teeth in treatment in the Department of Stomatology of First Affiliated Hospital of Dalian Medical University from October 2014 to August 2015 in need of root canal therapy randomly,among which 23 are males and 32 are females with ages ranging from 22 to 84.According to tooth position,divide them into group of anterior teeth(18 cases),group of dented premolars(19 cases),group of maxillary molar(10 cases),and group of mandibular molar(9 cases).All the ill teeth received root canal therapy for the first time;their apical foramina are fully developed without suffering from absorption damage;meanwhile,an experienced radiologist took two periapical films of paralleling technique and bisecting angle simultaneously before operation,and two doctors measured t he distance from the reference point of upper teeth of periapical film to root tip by means of compasses as well as vernier caliper.Two EWL(estimated working length)can be obtained through subtracting 1mm of the two mean values of measurements,which ar e remarked as EWL1 and EWL2.After opening dental pulp,extirpation of pulp and dredging root canal,the AWL(actual working length)of target teeth can be obtained through root tip position finder and diagnostic wire shooting method.Calculate the accurac y of estimated working length of root canal of periapical films in two projection ways by using statistical method separately,and carry out the statistical analysis of pairing t test on the statistical data of paralleling technique as well as bisecting angle,it is obvious by taking p<0.05 as difference.Results: In the aspect of accuracy,the precision rates of groups of anterior teeth and maxillary molar are 88.69% and 88.67%,their accuracy of bisecting angle is 66.67%,which means the precision rate of paralleling technique is high than bisecting angle obviously.However,the accuracy of paralleling technique in groups of dented premolars and mandibular molar are 88.89% and 100% separately,which are higher than the precision rates of 88.83% and 88.89% in bisecting angle.The statistical analysis result of pairing t test showed that the p values in the groups of anterior teeth and maxillary molar are 0.034 and 0.020,which are less than 0.05;therefore,it is regarded that the periapical films differences of paralleling technique and bisecting angle have statistical meaning in groups of anterior teeth and maxillary molar.On the contrary,the p values in groups of dented premolars and mandibular molar are 0.104 and 0.503 separately,which are higher than 0.05;thus,it is regarded that the difference of measuring working length of root canal by paralleling technique and bisecting angle periapical films in groups of dented premolars and mandibular molar do not have statistical meaning.Conclusion: Generally,in anterior teeth and maxillary molar areas,since the periapical film of paralleling technique is more accurate than the periapical film of bisecting angle,it is suggested to adopt periapical film of paralleling technique to assist in judging the working length of root canal.However,in dented premolars and mandibular molar areas,the ability of estimating the working length of root canal of paralleling technique is equal to that of bisecting angle,so bisecting angle is selected to satisfy clinical demands because it is convenient for operating. |
PDF Full Text Request