| Background:Dental pulp disease and periapical disease are the common bacterial and infectious diseases in oral clinic,and the effective treatment is root canal treatment.The key of root canal treatment is cleaning thoroughly,forming properly,disinfection strictlyl,and filling closely,so as to prevent the periapical disease and promote healing of periapical lesions.The maxillary molars in the rear arch,poor visibility of operation,and the root canal system of the maxillary molars are complicated,and it brings difficulties to the clinical treatment,therefor dentists need a comprehensive and systematic grasp of the anatomical morphology of the maxillary molars root canal system.At present,there are many research methods of the root canal system,and the cone beam CT(CBCT cone-beam,computed tomography)can display a clear,three-dimensional and intuitive anatomical morphology of the maxillary molars root canal system in coronal,sagittal,horizontal position.Objective:The anatomic structure and morphology of the root canal system of maxillary first and second molars in Shandong region were studied by CBCT technique,analysis of the root number,root canal number,type,length,and root canal orifice spacing with age and sex,and to provide the first data for further study of the root canal system of the maxillary first and second molars,and to provide theoretical basis for clinical treatment.Methods:A total of 1321 cone-beam computed tomography images of maxillary first and second molars were collected from 490 patients who visiting the Shandong University Stomatological Hospital radiology department between September 2015 to August 2017,and the patients' name,gender,age,teeth and other basic information were recorded,and at the same time analyzed and researched the following contents:?Tooth position;?Root number;?Number and type of root canal;?The distance from the root canal to the anatomical root hole;?The distance of root canal orifice,and analysed the correlation between age and sex.Results:1.Anatomical morphology of root and root canal of the maxillary first molars in Shandong region1.1 Root numberIn the 714 maxillary first molars,there were 700 teeth were 3 roots,the incidence was 98.04%;13 teeth were 2 roots,the incidence was 1.82%;1 tooth were 4 roots,the incidence was 0.14%;1 tooth were 0 root.1.2 Root canal numberIn the 714 maxillary first molars,there were 368 teeth were four canals,the incidence was 51.54%,and 367 teeth were MB2,the incidence was 51.40%,and 1 tooth were DB2,the incidence was 0.14%;344 teeth were three canals,the incidence was 48.18%;2 teeth were double root canals,the incidence was 0.28%;the incidence of single tube was 0.1.3 Root canal typeAccording to Vertucci root canal morphology classification,the largest number of root canal type was ? type of a total of 344 teeth in the 714 maxillary first molars,and the incidence was 48.18%.This study found that the double root canal 2 cases,and the root canal type were all ? type,and the types of three root canals were as follows:MB:There were more variation,with the largest number of type ?,a total of 344 teeth(48.31%),followed by type ?,a total of 143 teeth(20.08%),and again type ?,a total of 136 teeth(19.10%).DB:The largest number of type ?,a total of 708 teeth,the incidence was 99.44%.In this study,4 cases of distalbuccal canal variation were found,including 1 case of type?,2 cases of type ?,and 1 case of type 1-2-1-2-1-2-1-2.P:All were of type ?,the incidence was 100%.1.4 The distance from the root canal to the anatomical root holeIn the range of 4mm?18mm,and the maximum distribution was 7.1?12mm,the ratio was 87.31%;and the remaining was 12.1?15mm,the ratio was 8.15%;5.1?7mm,the ratio was 4.26%;15.1?18mm,the ratio was 0.19%;4?5mm,the ratio was 0.09%.1.5 The distance of root canal orificeIn the range of 0?8mm,and the maximum distribution of MB-DB was between 1.1?3mm,the ratio was 29.56%;and the remaining was 3.1?4mm,the ratio was 1.00%;0?1mm,the ratio was 0.39%;4.1?5mm and 7.1?8mm,the ratio were all 0.04%.The maximum distribution of MB-P was between 4.1?6mm,the ratio was 25.54%;and the remaining was 3.1?4mm,the ratio was 3.66%;6.1?7mm,the ratio was 1.74%;7.1?8mm,the ratio was 0.09%.The maximum distribution of DB-P was between 2.1?5mm,the ratio was 29.73%;and the remaining was 5.1?6mm,the ratio was 0.96%;1.1?2mm,the ratio was 0.31%;6.1?7mm,the ratio was 0.04%.The maximum distribution of MB-MB2 was between 1.1?3mm,the ratio was 2.88%;and the remaining was 0?1mm,the ratio was 0.48%;3.1?4mm.the ratio was 0.09%.The maximum distribution of MB2-P was between 2.1?5mm,and the ratio was 3.23%;and the remaining was 5.1?6mm.the ratio was 0.17%;1.1?2mm,the ratio was 0.04%.2.Anatomical morphology of root and root canal of the maxillary second molars in Shandong region2.1 Root numberIn the 607 maxillary second molars,there were 423 teeth were 3 roots,the incidence was 69.69%;109 teeth were 2 roots,the incidence was 17.96%;73 teeth were 1 root,the incidence was 12.03%;2 teeth were 4 roots,the incidence was 0.33%.2.2 Root canal numberIn the 607 maxillary second molars,there were 439 teeeth were three canals,the incidence was 72.32%;109 teeth were four canals,the incidence was 17.96%,and 108 teeth were MB2,the incidence was 17.79%,and 1 tooth were P2,the incidence was 0.16%;45 teeth were double root canals,the incidence was 7.41%;14 teeth were single canal,the incidence was 2.31%.2.3 Root canal typeAccording to Vertucci root canal morphology classification,the largest number of root canal type was ? type of a total of 421 teeth in the 607 maxillary second molars,and the incidence was 69.36%.This study also found the double root canals and single tube type,and the root canal types were all ? type,and the types of three root canals were as follows:MB:There were more variation,with the largest number of type ?,a total of 422 teeth(77.01%),followed by type ?,a total of 62 teeth(11.31%),and again type ?,a total of 19 teeth(3.47%).DB:The largest number of type I,a total of 547 teeth,the incidence was 99.82%.P:The largest number of type I,a total of 592 teeth,the incidence was 99.83%.This study also found the palatal second root canal 1 case,the type of root canal was 2-1-2-1.2.4 The distance from the root canal to the anatomical root holeThe distance of the root canals of each three canals to the anatomical root hole was from 4mm?18mm,and the maximun distribution was 7.1?11 mm,the ratio was 79.77%;and the remaining was 11.1?14mm,the ratio was 13.10%;5.1?7mm,the ratio was 6.34%;14.1?15mm,the ratio was 0.37%;4-5mm,the ratio was 0.31%;15.1?18mm,the ratio was 0.12%.The distance of the root canals of each double canals to the anatomical root hole was from 7mm?13mm,and mainly distribution between 8.1?12mm,the ratio was 91.11%;and the remaining was 7.1?8mm,the ratio was 6.67%;7mm and 12.1?13mm,the ratio were all 1.11%.2.5 The distance of root canal orificeIn the range of 0?9mm,and the maximum distribution of MB-DB was between 1.1?3mm,the ratio was 30.09%;and the remaining was 0?1 mm,the ratio was 1.10%;3.1?4mm.the ratio was 0.46%.The maximum distribution of MB-P was between 4.1?6mm,the ratio was 24.19%;and the remaining was 3.1?4mm,the ratio was 5.15%;6.1?7mm,the ratio was 1.68%;2.1?3mm,the ratio was 0.52%;7.1?9mm,the ratio was 0.12%.The maximum distribution of DB-P was between 3.1?5mm,the ratio was 24.48%;and the remaining was 2.1?3mm,the ratio was 5.38%;5.1?6mm,the ratio was 1.27%;1.1?2mm,the ratio was 0.41%;6.1?7mm.the ratio was 0.12%.The maximum distribution of MB-MB2 was between 1.1?2mm.the ratio was 0.81%;and the remaining was 2.1?3mm,the ratio was 0.29%;0?1mm,the ratio was 0,12%.The maximum distribution of MB2-P was between 2.1?4mm,and the ratio was 0.75%;and the remaining was 1.1?2mm and 4.1?5mm,the ratio were all 0.17%;5.1?8mm,the ratio was 0.12%.The maximum distribution of B-P(double root canal)was between 2.1?4mm,and the ratio was 2.08%;and the remaining was 1.1?2mm,the ratio was 0.29%;4.1?5mm,the ratio was 0.17%;5.1?6mm,the ratio was 0.06%.Conclusion:The anatomy form of root and root canal was complex and changeful of the maxillary first and second molar in Shandong region,especially mesialbuccal root canal,but the distalbuccal canal and palatal canal were also occurring mutate,and CBCT technology can be more clear,true to display the root and root canal form of maxillary first and second molar in Shandong region.The results of this study were as follows:?The maximum root number of maxillary first and second molars were 3 roots;??The incidence of MB2 of maxillary first molar was 51.40%,and maxillary second molar was 17.79%;?The mainly root canal type of maxillary first and second molars were type ?;The distance from the root canal to the anatomical root hole of maxillary first and second molars were mainly distribution between 7.1?13mm;?In the maxillary first and second molars,the maximum distribution of MB-DB was between 1.1?3mm,the maximum distribution of DB,P was between 2.1?5mm,the maximum distribution of MB-P was between 4.1?6mm,the maximum distribution of MB-MB2 was between 1.1?3mm,the maximum distribution of MB2-P was between 2.1?5mm,the maximum distribution of B-P was between 2.1?4mm.The results of this study can help dentists to know the root and root canal morphology and structure of maxillary first and second molar in Shandong region,and to location the root canal orifice more accurate,and determine the work length,so as to provide theoretical basis for clinical treatment and further study. |
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