CBCT Analysis Of The Thickness Of The Maxillary First Premolar Root Canal Wall And Its Effect On The Preparation Of Nickel-titanium Instruments

Background and objectiveThe purpose of root canal treatment is to preserve the teeth to exercise the chewing function,and the amount of residual tissue after treatment is critical to the functional state of the teeth after repair.Nickel-titanium instruments have good root canal crown opening and forming ability,but excessive root canal cutting can reduce the residual tissue of the teeth,and the bending resistance of the root canal is greatly reduced,increasing the risk of root canal perforation and vertical fracture.In this study,Cone-Beam Computed Tomography(CBCT)was used to compare and analyze the original thickness of the maxillary first premolar root canal wall and the thickness of the root canal wall after preparation of the nickel-titanium instrument.The weak point of the wall provides a theoretical basis for selecting the root canal preparation device and preventing concurrent the occurrence of the disease,and provides theoretical support for the research and design of other dental positions.MethodsAccording to the inclusion criteria,90 cases of maxillary first premolar CBCT images were collected at the Oral Medical Center of the First Affiliated Hospital of Jinan University.There were 60 cases of IV-type root canal CBCT image and 30 cases of I-type root canal CBCT image.The thickness of the original root canal wall of the two types of the coronal,the middle and the tip,and the thickness of the remaining root canal were measured separately,using mean±standard deviation((?)±s) indicates.The variance value of the wall was analyzed by analysis of variance to explore the weak point of the root canal wall.Results1.The mesial and distal walls of the coronal,middle and tip are smaller than the buccal and lingual wall;the closer to the anatomical root tip,the smaller the thickness of the root canal wall;the larger the preparation instrument model,the greater the root canal thickness reduction value.2.The thickness of the root canal wall was different in all directions at the same marking point before and after preparation.There was no significant difference between the mesial-distal,and the buccal-lingual in the pairwise comparison(P>0.05),near-middle-cheek,near-middle-tongue The difference between the mesial-buccal,the mesial-lingual,the distal-buccal,the distal-lingual was statistically significant(P<0.05).3.The thickness difference between the mesial and distal wall before and after the coronal,middle and tip preparation was statistically significant(P<0.05);while the I-type root canal buccal and lingual wall were only before and after the apical preparation.The thickness difference was statistically significant(P<0.05).There was no significant difference in thickness between the coronal and the middle before and after preparation(P>0.05).The IV-type root canal buccal and lingual wall were only before and after apical and middle preparation.The thickness difference was statistically significant(P<0.05),and the thickness difference between the coronal before and after root canal preparation was not statistically significant(P>0.05).Conclusion1.There is no significant difference in the thickness of the mesial-distal and buccal-lingual root canal wall between the I-type and the IV-type root canal of the maxillary first premolar.The mesial and distal walls are smaller than the buccal wall and the lingual wall.The closer to the anatomical tip,the smaller the difference between the buccal-lingual wall and the mesial-distalwall,the closer the root canal cross section is to a circular shape.2.The maxillary first premolar type I and IV root canal showed that the thickness of the root canal wall was reduced to less than 1 mm after the instrument was prepared in the mesial and distal wall of the middle segment of the root.Therefore,the middle segment of the root was marked as 5 mm away from the anatomical root tip.The mesial and distal wall are the weakest point of it,and should be taken care of when preparing the root canal.3.It is recommended to use F1 as the final completion of the I-type root canal of the maxillary first premolar.It is recommended to use F2 as the final completion of the IV root canal of the maxillary first premolar.In summary,the thickness of the root canal wall in each direction tends to decrease with the increase of the type of the preparation instrument,but the variation of the buccal and lingual wall is not obvious,especially in the root of the coronal and middle.It is recommended to use the modified H-files to clean the root canal along the root canal wall after the preparation of the nickel-titanium instrument is completed.The root canal is disinfected with hydrogen peroxide and sodium hypochlorite,and the root canal is ultrasonically shaken to ensure the quality of the root canal preparation.Due to the lack of research funding and research time,this study is to further study and analyze the CBCT images before and after the actual root canal preparation of the isolated teeth in accordance with the inciusion criteria,and consider the experimental results compared with other commonly used nickel-titanium instruments.The accuracy of the appeal conclusion and reference options for the model of the maxillary first premolar preparation device.