| [Objectives]The aim of the study was to investigate the thickness of the crowns and roots and the buccolingual(BL)and mesiodistal(MD) diameters of the roots of Chinese maxillary and mandibular canines. The aim of this study was to provide an anatomic basis for full-crown restorations and post-and-core restorations.[Materials and Methods]CBCT data of 150 Chinese maxillary canines and 150 Chinese mandibular canines ware collected from Hospital of Stomatology affiliated to Zhejiang University School of Medicine from June.2014 to June.2015,age from 20-50 years old.Operating software NNT built in CBCT-imaging systems was used to measure the scanning layers from the cusp to the roof of pulp chamber(A),cusp to the cement-enamel junction(CEJ)(B) and from CEJ to the apex(C).The cross-sections at the middle third, cervical third, CEJ, cervical middle(CM), middle(M), apical middle(AM) were used to measure the BL,MD diameters of the root and the thickness of root walls was analyzed. The probability that the residual thickness of root walls more than 1.0mm in BL and MD after post space preparation by 1-6# Peeso reamers was calculated. The data was analyzed by SPSS.[Results]All the data ware satisfied with normal distribution. The lengths of crowns and roots of maxillary canines were presented as Middle±25/P75. The length of crowns and roots of maxillary canines was 7.6±(7.0/8.0)mm,16.9±(15.5/18.2)mm obeying normal distribution.The mesial thickness of maxillary canines’root walls was 2.3±(2.1/2.5), 1.9±(1.6/2.1),1.6±(1.4/1.8),1.4±(1.2/1.6)mm at CEJ,CM,M,AM. The distal thickness of root walls was 2.5±(2.3/2.7),1.9±(1.6/2.1),1.7±(1.4/1.9),1.4±(1.2/1.6)mm at CEJ,CM,M,AM. The diameters of roots was 1.2±(1.0/1.3),1.0±(0.9/1.2),0.9±(0.8/1.0), 0.8±(0.6/0.8)mm in MD direction at CEJ,CM,M,AM.At AM in maxillary canines, the probability that the residual thickness of the root walls remaining no less than 1mm after 2# Peeso reamers’preparation was 92%. After 3# Peeso reamers’preparation,85% was no less than lmm and 92% was no less than 0.9mm. After 4# Peeso reamers’ preparation,75% was no less than 1.0mm,85% was no less than 0.9mm,92% was no less than 0.8mm.After 5# Peeso reamers’ preparation, 61% was no less than 1.0mm,75% was no less than 0.9mm,85% was no less than 0.8mm,92% was no less than 0.7mm. After 6# Peeso reamers’ preparation,47% was no less than lmm,61% was no less than 0.9mm,75% was no less than 0.8mm,85% was no less than 0.7mm,92% was no less than 0.6mm.At M, after 5# Peeso reamers’ preparation,89% was no less than 1mm,92% was no less than 0.9mm. After 6# Peeso reamers’ preparation,85% was no less than lmm,89% was no less than 0.9mm.At AM in maxillary canines, the probabilities that the residual thickness of the root walls remaining no less than 1mm after yellow, red, blue fiber post reamers’preparation were 96%,94%,92% in MD direction.The length of crowns and roots of maxillary canines was 7.4±(7.0/8.0)mm, 16.2±(15.0/17.3)mm obeying normal distribution.The mesial thickness of maxillary canines’root walls was 2.1±(2.0/2.3), 1.7±(1.6/1.9),1.5±(1.4/1.7),1.3±(1.2/1.5)mm at CEJ,CM,M,AM. The distal thickness of root walls was 2.3±(2.1/2.5),1.9±(1.6/1.9),1.6±(1.3/1.7),1.4±(1.2/1.4) mm at CEJ,CM,M,AM. The diameters of roots was 1.0±(1.0/1.2),1.0± (0.8/1.1),0.9±(0.8/1.0), 0.8±(0.6/0.8)mm in MD direction at CEJ,CM,M,AM.At AM in madibular canines, the probability that the residual thickness of the root walls remaining no less than lmm after 2# Peeso reamers’ preparation was 87%,94% was no less than 0.9mm. After 3# Peeso reamers’preparation,75% was no less than 1mm and 87% was no less than 0.9mm,94% was no less than 0.8mm. After 4# Peeso reamers’preparation,60% was no less than 1.0mm,75% was no less than 0.9mm,87% was no less than 0.8mm.After 5# Peeso reamers’preparation,44%was no less than 1.0mm,60% was no less than 0.9mm,75% was no less than 0.8mm,87% was no less than 0.7mm,94% was no less than 0.6mm. After 6# Peeso reamers’ preparation,28% was no less than lmm,44% was no less than 0.9mm,60% was no less than 0.8mm, 75% was no less than 0.7mm,87% was no less than 0.6mm,94% was no less than 0.5mm.At M, after 4# Peeso reamers’preparation,88% was no less than lmm,94% was no less than 0.9mm. After 5# Peeso reamers’preparation,80%was no less than 1mm,88% was no less than 0.9mm,94% was no less than 0.8mm. After 6# Peeso reamers’ preparation,69% was no less than 1mm,80% was no less than 0.9mm,88% was no less than 0.8mm,94% was no less than 0.7mm.At AM in mandibular canines, the probabilities that the residual thickness of the mandibular canine root walls remaining no less than lmm after yellow, red, blue fiber post reamers’preparation were 93.6%,90.5%,86.5% in MD direction.Finishing 2mm cutting, the probability of occlusal surface thickness more than 2.5mm was 84%,100% was more than 1.5mm in maxillary canines. Finishing 2mm cutting, the probability of occlusal surface thickness more than 2.5mm was 72%,100% was more than 1.5mm in mandibular canines.[Conclusions]1.According to the limited study,it is suggested not to prepare the root canal of Chinese maxillary canine beyond AM using 3# Peeso reamer as possible, and not to use 4# Peeso reamer or larger reamers.The blue marker fiber post could be used for Chinese maxillary canines.2.It is suggested not to prepare the root canal of Chinese mandibular canine beyond M, using 3# Peeso reamer or larger reamers.The red marker fiber post could be used for Chinese mandibular canine.3.The mandibular and maxillary canine preparation can follow the basic requirements of tooth preparation in the Prosthodontics textbook.[Objectives] To analyze the buccolingual tilting angle on abutments allowing the restoration of fixed partial denture.[Materials and Methods]Using space geometry and Matlab 6.5 mathematical analyzing software constructed mathematical model to calculate the abutments’ buccolingual tilting angle. The 3D graph database of one set of teeth was described with parameters,including h,d,D, a.The tooth mobility was 50μm,the thickness of spacer was 45μm and the adhesive thickness was 20 μm. A’B’was the projection of the tooth’s axis AB in the plane. The angle between A’B’and D was ε.[Results]Mathematical model of fixed partial denture was constructed in which the second premolar tilted toward the second molar. The teeth’axis tilted at 8.1°at most when the degree of polymerization was 5° and tilted at 14.4° at most when the degree of polymerization was 10°.[Conclusions]According to the limited study,it was first time theoretical evidence that the fixed partial dentures could be placed with a slight rotation of insertion considering the movement of the tooth ligament,the convergent degrees of the tooth preparation(6°or 10°) and the film thickness of cements. |
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