Shandong Han Elderly The First Premolars Anatomy Measurements And Observations

Objective:To aim of this study was to measure the anatomy morphology of the first permanent premolars of Han middle age and old people in Shandong region and provide anatomic data and theoretic basis for clinical treatment, education, scientific research and endodontic surgery in department of Stomatology.Methods:1. A total of 174 first premolar of 45-81 age in Shandong province and 30 first premolars of double roots which were collected from June of 2008 to December of 2010, were divided into four groups for position and sex. Marked the basic information such as name, sex, age, high, nation, position, and the reason of extract a teeth.2. The teeth were measured according to the established method, including the length of tooth, height of dental crown, length of dental root, the ratio of height of dental crown and length of dental root, width of dental crown, width of dental neck, depth of dental crown, depth of dental neck. All the data were compared with which of the youth and junior in Shandong region. Then the data were analyzed using the SPSS software package.3. The following observations were made by naked eyes:the root type, the root shape and the place of the root branch of the first permanent premolars. The distance from the root branch to enamelo-cemental junction was recorded.4. The following observations were made by root canal microscope:the number, the shape and the position of root foramina, the distance from root foramina to anatomy apical.5. The following observations were made by root canal microscope:the distance of buccal root to palatal root of maxillary teeth. The location of palatal root marked as buccal root was recorded.Results:1. Anatomic data of the first permanent premolars of Han middle age and old people in Shandong region were obtained. In each group, the ratio of height of dental crown and length of dental root had the biggest coefficient of variation, which was same to youngsters. The different group had different index on the smallest coefficient of variation. The result of T-test was that the following anatomic data of the maxillary first premolars such as the length of tooth, height of dental crown, length of dental root between the different sex had high statistical significance (p<0.01). The length of tooth, length of dental root, the ratio of height of dental crown and length of dental root, width of dental neck of mandibular first premolars between the different sex also had high statistical significance.(p<0.01). Most anatomic data of the maxillary or mandibular first permanent premolars between different age also had statistical significance(P<0.05).The result of the correlation analysis was that the correlation coefficient of tooth length-dental root length, tooth length-height of dental crown and depth of dental crown-depth of dental neck had significant statistical significance (P<0.01)2. The maxillary first permanent premolars had included 13.48%double roots,34.83% straight root,44.94% curve to mesiodistal directions,1.12% curve to buccolingual directions.5.62% "s" shaped root; the mandibular first permanent premolars had included 1.18%double roots,41.18% straight root,51.76% curve to mesiodistal directions,3.53% curve to buccolingual directions,2.35% "s" shaped root.18.18% of maxillary first permanent premolars and 58.33%of mandibular first permanent premolars had no root grooves.3. Most maxillary first permanent premolars had 2 root foramina and only 35.12% of the root foramina located at apices. Most mandibular first permanent premolars had 1 root foramina and there were about 36.59% root foramina located at apices.4. About 96.7% of buccalroot apices were located in midcourt line of buccalroot which was parallel with tooth axial length. At the mesiodistal direction, about half of palatal root overlapped with buccalroot. The average distance between palatal root and buccalroot was 5.27mm.Conclusion:1. The anatomic data of maxillary or mandibular first permanent premolars between different sexes of the same position has some differences. Compared with the data of youngsters, the difference of most measurement has statistical significance.2. Most of the first permanent premolars of Han middle age and old people in Shandong region have one root and curve to mesiodistal direction. Few maxillary first permanent premolars and half of mandibular first permanent premolars have no root grooves.3. Most of the maxillary first permanent premolars had 2 root foramina and most of the mandibular first permanent premolars had 1 root foramina. About half of the root foramina located at the side of apices.4. The radio of double roots of maxillary first permanent premolars is low, and the difference between the two roots is significant.