Anatomical Study Of The Root And Root Canal System Of Mandibular Second Premolar

The mandibular second premolars are prone to adjacent caries and wedge-shaped defects because of the anatomical characteristics of the teeth and the position of the dental arch.It is necessary to use the root canal therapy to cause pulpitis and even periapical periodontitis after treatment.The teeth usually need regular crown repair,and the post crown is still the most commonly used repair program.The key to successful treatment is the good understanding of the root canal system.At present,there is relatively little research on the mandibular second premolar,especially its root canal system.However,in the clinical treatment of oral cavity repair,we have found that the second premolar still has more special conditions,such as with age,With the continuous accumulation of external stimuli,the repair or secondary dentine in the root canal is gradually formed and thickened,resulting in the smaller medullary canal and various degrees of calcification or even complete blockage of the root canal,making the treatment of the tooth complex Change.On the other hand,calcified deposited tooth tissue can increase the thickness of remaining tooth tissue and increase resistance.In this experiment,a dental magnifier was used to study the type distribution characteristics of the occlusal surfaces of the mandibular second premolar at different ages.The CBCT image measurement method was used to study age-related changes in the roots and root canals of mandibular second premolars.Changes in the system;the influence of the thickness of the buccal and lingual wall in the root and neck of the mandibular second premolar,and in the root and the 1/3 of the apex;the angle relationship between the mandibular second premolar and the long axis of the root and the medullary canal;The distance between the long axis direction and the intersection between the occlusal surface and the central fossa.The results showed that the morphology of the occlusal surface of mandibular second premolars was mostly H,Y,and U.Different types of occlusal surfaces had different opening points,and there was no significant effect on aging.Mandibular second premolars were most common with type I root canals,but some teeth still had V-shaped canals.Aging changes lead to the accumulation of wear caused by the narrowing of the pulp cavity and the root canal,leading to a decrease in the height of the buccal medulla and a decrease in the angle of intersection with the buccal boundary of the buccal and lingual enamel.The near-distal middle wall and the bucco-lingual wall of teeth also gradually thicken as they age.This is more evident in the lingual wall.The angles of the pulp and pulp of the second mandibular second premolar vary with the individual,and the linear distance between the long axis of the root pulp and the occlusal surface and the tip of the lingual surface varies with the individual.The results showed that the proportions of U,Y,and H type occlusal surface of the mandibular second premolar were approximately 26.8%,31.1%,and 42.1%;the type of root canal was most common with a ratio of up to 96.6%,but there were still a small number of A V-shaped root canal appears in the tooth.When it extends from the medullary cavity to the apex of 1/3,it divides into two tubes and extends independently to the apical foramen;21 to 50 years old,the buccal ridge-buccal enamel bone interface and the bucco-lingual enamel cement The mean value of the intersection angles of the mass boundaries was about 36.1°,and there was no statistical difference between the groups,P>0.05.The angles of the teeth after the age of 50 years decreased,the average value was about 29.1°,and the angle of teeth after the age of 70 was significantly reduced to 23.90.The fonmer had statistically significant differences,P<0.05.The thickness of the mesial and buccal tongue walls in the near and far were significantly changed.For the same tooth,the thickness of the root neck was greater than that in the root.The thickness in the root was greater than the thickness of the apex 1/3,and the thickness of the buccal wall gradually decreased.The thickness of the lingual wall is greater than the thickness of the cheek wall,which is more pronounced in the root area,and the distal wall is generally thicker than the proximal wall.There was a statistical difference,p<0.05.The angles of the long axis of the crown and the root canal are not unique.The angle ranges from approximately 0° to 39° with an average of approximately 17.3°.The distance between the intersection point of the long axis of the root canal and the occlusal surface and the central fossa of the occlusal surface was 0.20-5.60 mm,and the average value was 2.70 mm.We conclude from this experiment that the percentage of the morphology of the mandibular second premolars is further clarified.The distribution of the three types of morphology is average and the positions of the different open medullary points are different.Through CBCT,it was further confirmed that the root canal system of mandibular second premolar was variability,and age-related changes in the angle of the connection line between the bony lingual and buccal enamel of the mandibular second premolar were changed,with age increasing Smaller,and age-related changes in the root neck,root 1/2,apical 1/3 of the root canal wall thickness have changed,with the age of the root canal wall thickening.The average of the long axis angles of the pulp and the root canal is clearly defined.The straight line distance between the long axis of the root canal and the occlusal surface and the tip of the tongue provides a guide for clinical treatment of the root canal and restoration of the post and crown.To prevent its omission to treat the root canal,the side of the root canal,root fractures and so on.