Traditional descriptive observation and advanced geometric morphometric are employed to study the morphological characteristics of Zhoukoudian mandibular premolars, and simultaneously with the specimens of Australopit...Traditional descriptive observation and advanced geometric morphometric are employed to study the morphological characteristics of Zhoukoudian mandibular premolars, and simultaneously with the specimens of Australopithecus, African early Homo, Homo erectus in other areas of Asia except Zhoukoudian, Europe Pleistocene fossil hominins, and recent Chinese (72 P3 and 69 P4 on the whole) being included as comparisons. Results suggest obvious evolutionary changes in the occlusal morphology and crown outline shape of mandibular premolars. Australopithecus P3s are found with extremely asymmetrical crown outlines, prominent mesial and distal vertical grooves on the buccal side, open foveas, and well-developed talonids, and P4s with similarly asymmetrical crown outlines, distinct mesial and distal vertical grooves on the buccal side, and "H" type of grooves combination. These characteristics are also expressed in the later hominin specimens, but with a decreased extent and lower frequency. The P3s of recent Chinese, slightly asymmetrical in the crown lingual contours, and P4s, basically symmetrical in the crown outlines, become faint or disappeared in the mesial or distal vertical buccal grooves, and decreased in the talonid size. It is suggested that Zhoukoudian mandibular premolars preserve some primitive traits of earlier hominins, including asymmetrical crown outlines and prominent mesial and distal vertical grooves of buccal side. Moreover, Zhoukoudian specimens exhibit obvious morphological variation between individuals, expressed mainly by aspects of mesial and distal vertical buccal grooves in various degrees, symmetry or asymmetry extent of crown lingual contour, relative location of polygon to the corresponding surrounding outline, as well as the relative size of talonid. When compared with Homo erectus from the other areas of Asia, Zhoukoudian specimens show their similarity with those of Xichuan and S-1, and at the same time great discrepancy with S-6 in the occlusal morphology and crown outline shape. When it 展开更多
Reportedly,maxillary premolars are the most complex teeth for performing endodontic treatment,[1] with root canals varying based on race,genetic predisposition,diet,region,gender,[2] and perhaps age.To date,few detail...Reportedly,maxillary premolars are the most complex teeth for performing endodontic treatment,[1] with root canals varying based on race,genetic predisposition,diet,region,gender,[2] and perhaps age.To date,few detailed studies have been conducted to assess number of roots and root canal morphology of maxillary premolars in the elderly.The present study analyzed root canal morphology of maxillary premolars in elderly individuals using cone-beam computed tomography （CBCT）,which has substantial clinical value in guiding endodontic treatment.[3]展开更多
Aim : To determine the variations in the root and canal morphology of the maxillary first premolar teeth in a Ugandan population. Methodology : Extracted maxillary first premolar teeth (n = 202) were evaluated in this...Aim : To determine the variations in the root and canal morphology of the maxillary first premolar teeth in a Ugandan population. Methodology : Extracted maxillary first premolar teeth (n = 202) were evaluated in this study. The specimens had their pulp chambers de-roofed. They were decalcified in nitric acid and made transparent with methyl salicylate. Indian ink was injected into the root canals to display their configuration. Results : One hundred and forty eight (73.3%) of the specimens had two roots, of which 16.9% (n = 25) had fused roots. About 26.7% (n = 54) of the specimens were single rooted. Eleven (20.4%) of the single rooted specimens had one canal of either Vertucci type I, III, V or VII configuration while 79.6% (n = 43) of the specimens had two canals of either Vertucci type II, IV or VI configuration. The two-rooted specimens exhibited Vertucci type IV and VIII canal configuration: 96.6% and 3.4%, respectively. The single rooted teeth had a higher prevalence of lateral canals, canal intercommunications and multiple apical foramina as compared to the two-rooted specimens. Conclusion : The maxillary first premolar teeth in this Ugandan population showed a higher prevalence of two-root morphology with majority of the roots having Vertucci type IV canal configuration. There was no three-root anomaly recorded in the present material.展开更多
基金Supported by the National Natural Science Foundation of China (Grant No. 40772016)International Cooperation Program of MST of China (Grant No. 2007DFB20330)Cultural Relics Protected Program in Danjiangkou Reservoir Area of the South-to-North Water Diversion Project Held by Hubei Cultural Relics Bureau (Grant No. NK13)
文摘Traditional descriptive observation and advanced geometric morphometric are employed to study the morphological characteristics of Zhoukoudian mandibular premolars, and simultaneously with the specimens of Australopithecus, African early Homo, Homo erectus in other areas of Asia except Zhoukoudian, Europe Pleistocene fossil hominins, and recent Chinese (72 P3 and 69 P4 on the whole) being included as comparisons. Results suggest obvious evolutionary changes in the occlusal morphology and crown outline shape of mandibular premolars. Australopithecus P3s are found with extremely asymmetrical crown outlines, prominent mesial and distal vertical grooves on the buccal side, open foveas, and well-developed talonids, and P4s with similarly asymmetrical crown outlines, distinct mesial and distal vertical grooves on the buccal side, and "H" type of grooves combination. These characteristics are also expressed in the later hominin specimens, but with a decreased extent and lower frequency. The P3s of recent Chinese, slightly asymmetrical in the crown lingual contours, and P4s, basically symmetrical in the crown outlines, become faint or disappeared in the mesial or distal vertical buccal grooves, and decreased in the talonid size. It is suggested that Zhoukoudian mandibular premolars preserve some primitive traits of earlier hominins, including asymmetrical crown outlines and prominent mesial and distal vertical grooves of buccal side. Moreover, Zhoukoudian specimens exhibit obvious morphological variation between individuals, expressed mainly by aspects of mesial and distal vertical buccal grooves in various degrees, symmetry or asymmetry extent of crown lingual contour, relative location of polygon to the corresponding surrounding outline, as well as the relative size of talonid. When compared with Homo erectus from the other areas of Asia, Zhoukoudian specimens show their similarity with those of Xichuan and S-1, and at the same time great discrepancy with S-6 in the occlusal morphology and crown outline shape. When it
文摘Reportedly,maxillary premolars are the most complex teeth for performing endodontic treatment,[1] with root canals varying based on race,genetic predisposition,diet,region,gender,[2] and perhaps age.To date,few detailed studies have been conducted to assess number of roots and root canal morphology of maxillary premolars in the elderly.The present study analyzed root canal morphology of maxillary premolars in elderly individuals using cone-beam computed tomography （CBCT）,which has substantial clinical value in guiding endodontic treatment.[3]
文摘Aim : To determine the variations in the root and canal morphology of the maxillary first premolar teeth in a Ugandan population. Methodology : Extracted maxillary first premolar teeth (n = 202) were evaluated in this study. The specimens had their pulp chambers de-roofed. They were decalcified in nitric acid and made transparent with methyl salicylate. Indian ink was injected into the root canals to display their configuration. Results : One hundred and forty eight (73.3%) of the specimens had two roots, of which 16.9% (n = 25) had fused roots. About 26.7% (n = 54) of the specimens were single rooted. Eleven (20.4%) of the single rooted specimens had one canal of either Vertucci type I, III, V or VII configuration while 79.6% (n = 43) of the specimens had two canals of either Vertucci type II, IV or VI configuration. The two-rooted specimens exhibited Vertucci type IV and VIII canal configuration: 96.6% and 3.4%, respectively. The single rooted teeth had a higher prevalence of lateral canals, canal intercommunications and multiple apical foramina as compared to the two-rooted specimens. Conclusion : The maxillary first premolar teeth in this Ugandan population showed a higher prevalence of two-root morphology with majority of the roots having Vertucci type IV canal configuration. There was no three-root anomaly recorded in the present material.
