第一前磨牙桩道预备后剩余根管壁厚度的研究

目的 采用解剖学方法,测量第一前磨牙桩道预备前后根管壁厚度,指导临床合理选择桩道预备器械.方法 收集上下颌第一前磨牙各30颗作为实验样本,用游标卡尺测量原始及分别用1、2、3号P型钻桩道预备后末端剩余根管壁的厚度.结果 牙根各项指标测量值均呈正态分布,对于双根管上颌第一前磨牙和单根管下颌第一前磨牙,3号P型钻预备后,近...     

上颌前牙三种不同方法根管预备后剩余根管壁厚度的研究

目的探讨上颌前牙根管预备后距根尖4mm处根管壁的最小厚度,为临床预备桩腔末端的宽度提供理论依据。方法离体直单根管上前牙60个,随机分为3组（n=20）进行根管预备,A组：不锈钢根管锉常规法;B组：G型钻根管冠部预处理＋不锈钢根管锉常规法;C组：手用ProTaper镍钛根管锉冠向下法。所有牙齿用金刚砂片分别在距根尖4mm处和釉牙骨质界处截断牙根,截断面垂直于根管。用游标卡尺测量断面根管近中壁、远中壁最薄处厚度。结果三种方法根管预备后距根尖4mm处和釉牙骨质界处剩余根管壁厚度均数都大于1mm。釉牙骨质界处与距根尖4mm处剩余根管壁厚度之间行直线相关分析,只有B组釉牙骨质界处与距根尖4mm处远中壁剩余根管壁厚度之间存在线性相关,其它组之间均不存在线性相关。结论对于大多数病例,经三种方法根管预备后,推荐使用3#P型钻预备上颌前牙桩腔末端。     

口腔内科学——龋病及牙体硬组织非龋性疾病

银汞粘接剂和银汞充填术后敏感症；下颌第一恒磨牙Ⅰ类洞型三维有限元模型的建立；瓷化树脂与银汞合金治疗恒磨牙龋损的临床比较；两种材料修复楔状缺损的黏接性能对比研究；上颌前磨牙桩道预备后剩余根管壁厚度和抗折强度的研究；……[编者按]     

上颌第一前磨牙根管预备后根管壁厚度的研究

上颌第一前磨牙的牙根解剖形态较复杂 ,多有双分叉根、根面沟和近中凹面[1] 。所以根管预备后 ,根管壁厚度变薄 ,可能出现牙本质壁薄弱 ,甚至根折 ,将影响根管治疗术后修复效果。本实验对上颌第一前磨牙根管预备后 ,根管壁厚度进行测量研究 ,以对根外形有更多的了解。1　材料和方法10 6个上颌第一前磨牙 ,于釉牙骨质界最高点截去牙冠。然后作根管预备 ,根管工作长度距根尖 2ｍｍ[2 ] ,用ＴＲ -ＺＸ电动旋转根管锉预备根管至 # 40 ,用 3 0ｍＬ/Ｌ过氧化氢液和生理盐水交替冲洗 ,吸干 ,氧化锌丁香油糊剂加牙胶尖侧方加压充填根管 ,氧化锌丁香…     

CBCT诊断双侧上下颌第一前磨牙多根并多根管1例

根管治疗成功的关键在于对根管系统的解剖形态有准确认识,并对其进行完善的预备、消毒与充填。上颌第一前磨牙多为双根双根管,下颌第一前磨牙多为单根单根管,     

应用锥形束CT对成人上颌前磨牙牙根和根管系统形态的研究

目的：运用锥形束CT（CBCT）观察中国人群上颌前磨牙的牙根和根管系统的解剖形态,为临床根管治疗提供影像学依据。方法：选择200名患者的双侧上颌前磨牙（上颌第一前磨牙、上颌第二前磨牙各358颗）的CBCT扫描数据,使用NNT软件分析上颌第一、第二前磨牙的牙根数、根管数、根管分型以及双侧对称情况。结果：上颌第一前磨牙主要为单根（65.92%）和双根（33.80%）。上颌第二前磨牙主要为单根（93.85%）。上颌第一前磨牙的根管系统主要为双根管（84.36%）。上颌第二前磨牙的根管系统单、双根管比例接近（分别为52.79%和46.08%）。上颌第一前磨牙主要根管分型为：Ⅳ型（48.32%）、Ⅱ型（24.30%）和Ⅰ型（12.56%）。上颌第二前磨牙主要根管分型为：Ⅰ型（51.68%）、Ⅱ型（21.51%）和Ⅳ型（14.25%）。上颌第一、第二前磨牙的根管分型左右对称（对称率分别为74.57%和81.29%）。上颌前磨牙根管系统的主要变异为：管间交通支、颊根C形根管和多根管（树形根管或神经根样根管）。结论：上颌第一、第二前磨牙的根管系统主要为单根管和双根管。术前了解根管形态的变异是治疗成功的关键因素。     

离体的上颌第一前磨牙的根管和牙根情况的研究

目的 :观察上颌第一前磨牙的牙根及根管形态。方法 :115个离体的上颌第一前磨牙 ,对牙齿进行近远中向X线照像 ,然后从根中 1/3横断 ,按Vertucci :分类法对根管系统进行记录。结果 :74个牙是单根 (64 % ) ,41个牙是双根 (3 6% ) ,双根牙根管均是Ⅰ型 (1) ,即每个牙均是 2个根管 ,每个根 1个根管 ,而 3 9%的单根牙是 1个根管 ,61%的单根牙有 2个根管 [Ⅱ型 (2 1) ,Ⅳ型 (2 ) ,Ⅴ型 (1 2 ) ]。结论 :上颌第一前磨牙的根管类型相对复杂。     

左上颌第二前磨牙3根3根管1例

前磨牙根管系统较复杂,上颌第二前磨牙约75%为单根管,双根管比例约24%,3根3根管的报道较少。笔者报告左上颌第二前磨牙3根3根管1例。     

不同桩核系统修复上颌前磨牙双根管的抗折力研究

目的 比较不同桩核系统修复上颌前磨牙双根管的抗折强度.方法 将36颗因正畸拔除的上颌第一前磨牙,沿釉牙本质界冠方2mm水平切除牙冠,常规根管治疗后随机分为A、B、C三组,A组给予铸造镍铬合金桩核+金属全冠;B组给予MACROLOCKT石英纤维桩+树脂核+金属全冠,C组给予TENAX玻璃纤维桩+树脂核+金属全冠修复.应用力学试验机进行抗力性检测,记录试件破坏时施力的大小,观察试件破坏的形式及部位.结果 A组、B组、C组的离体牙桩核冠修复后牙体折断时的最大载荷分别为(1059.11±123.54)N、(1075.17±64.37)N、(1341.81 ±128.11)N.三组抗折强度两两比较,没有显著性差异(P＞0.05).A组不可复性折断明显多于B组和C组,差异有统计学意义(P＜0.05),B组与C组的抗折强度、破坏性折断例数比较,差异无统计学意义(P＞0.05).结论 采用不同桩核系统修复上颌前磨牙双根管的抗折强度无明显差异.玻璃纤维桩与石英纤维桩极大降低了根折率,有利于此类根管的保留和再修复.     

自凝塑料-嵌体蜡制作后牙分部桩核熔模的方法

核桩冠是残根残冠的主要修复方法之一 ,铸造桩核的应用已日趋广泛。单根前磨牙及通过根管预备使双根管相互平行的前磨牙 ,桩核熔模制作相对容易。不能通过根管预备使双根管相互平行的前磨牙、磨牙及多根磨牙 ,铸造桩核只能采用分部铸造的方法 ,熔模制作相对复杂。作者用自凝塑胶—嵌体蜡联合应用制作后牙分部桩核熔模 ,经临床使用取得了比较满意的结果。1　材料和方法1.1　适应证的选择凡是不能通过根管预备使 2个根管相互平行的前磨牙、磨牙及多根磨牙的残根残冠。且残根残冠已经完善的根管治疗 ,X线牙片上显示尖周无炎症 ,根长在 1.0cm以…     

Residual thickness of root in first maxillary premolars with post space preparation

It has been suggested that, to ensure tooth strength, a minimum of 1 mm of root wall thickness should be left after post preparations. The purpose of this study was to determine the instrument diameter that will not affect this measurement in maxillary first premolars. Post preparations were made in 106 teeth with one and two root canals at a working depth equal to the anatomical crown length, with 0.70, 0.90, 1.10, 1.30, 1.50, and 1.70 mm diameter instruments. Sections were cut perpendicular to the long axis of the tooth at the cervical and apical ends of each preparation, and the minimum width of residual root was measured on each wall, at both sites. A binocular microscope with a micrometer eyepiece was used. At the cervical level of the preparation, no group showed a wall thickness < 1 mm. Data for the apical sections was statistically analyzed, and the corresponding confidence limits were calculated with 95% confidence on the mean. The results show that the minimum residual thickness was only preserved when 0.70 mm instruments were used in single-canal roots and when 1.10 mm or smaller instruments were used for two-canal roots. This seemingly anomalous result occurs because fluting on both the mesial and distal sides of the root impinge on single canals, whereas dual canals are buccally or lingually displaced to an area of thicker root diameter.     

Residual dentin thickness in bifurcated maxillary first premolars after root canal and post space preparation with parallel-sided drills

STATEMENT OF PROBLEM: The primary factor that determines the prognosis of endodontically treated and restored teeth is preservation of sound dentin. The potential of these teeth to fracture is directly related to the amount of dentin removed. PURPOSE: The purpose of this study was to measure residual dentin thickness of bifurcated maxillary first premolars, in vitro, after root canal and conservative post space preparation. MATERIAL AND METHODS: Human premolars (n=13) with bifurcation at the junction of cervical and middle root thirds were embedded in a muffle device and horizontally sectioned 2, 4, and 6 mm apically to the cement-enamel junction. Residual dentin thickness was measured at the buccal, lingual, mesial, and distal aspects, apically to the bifurcation, and at the buccal or lingual, mesial, and distal aspects, coronally to the bifurcation. This procedure was repeated at baseline, after endodontic preparation (K-40 file), and after preparing the post space (ParaPost drills Nos. 3 and 4). Residual dentin thickness was analyzed using 3- or 4-way repeated measures ANOVA (alpha=.05). RESULTS: Endodontic therapy and post preparation reduced more dentin in the bifurcation aspects of both roots compared to outer aspects (P=.001). Post space preparation jeopardized the roots due to a residual dentin thickness of less than the recommended minimum 1-mm thickness in 61% (lingual) and 77% (buccal) of roots. CONCLUSIONS: Lack of residual dentin thickness after post preparation implies that the use of posts in maxillary first premolars should be limited. When mandatory, it is recommended that the lingual root be used and the buccal root be avoided.     

Residual dentin thickness in mandibular premolars prepared with gates glidden and ParaPost drills

STATEMENT OF PROBLEM: The main factor that determines the prognosis of restored pulpless teeth is preservation of sound dentin. PURPOSE: This study evaluated the residual dentinal thickness (RDT) of mandibular premolars after preparation of post space with Gates Glidden and ParaPost drills. MATERIAL AND METHODS: Twelve extracted single canal mandibular premolars were embedded in clear polyester resin to the cementoenamel junction (CEJ) in a muffle device. Three horizontal sections were made 1, 3, and 5 mm apical to the CEJ. Mesiodistal (MD) and faciolingual (FL) axes were carefully marked and the RDT was measured for each slice. Each tooth slice was reassembled in the muffle device with orientation pins, then secured with stabilizing pins. This procedure was repeated after enlarging the root canal to K-40 file and preparing the coronal root canal space with Gates Glidden drills and ParaPost drills Nos. 3, 4, and 5. RESULTS: Residual dentinal thickness in a MD direction was 3.77 +/- 0.51 mm in the unprepared upper slice and 2.23 +/- 0.31 mm in the No. 5 ParaPost drill prepared lower slice, for a difference of 41%. The corresponding values for the FL direction were 4.35 +/- 0.51 mm and 4.08 +/- 0.46 mm, respectively (6%). CONCLUSION: The average dentinal thickness 5 mm below the CEJ in the mesial and distal directions after post space preparation approached the accepted minimal 1 mm. A conservative approach to post space preparation was advocated.     

使用不同成形钻桩道预备后根端微渗漏的实验研究

目的:比较不同纤维桩成形钻与peeso钻对根尖微渗漏的影响。方法:选取34颗离体上颌前牙,分别进行根管充填,后以peeso钻(A组),coltène钻(B组),bisco钻(C组),RTD钻(D组)进行根管预备。E组不进行预备。用染料渗透法评价各组根尖封闭能力,并进行统计学分析。结果:各组均值分别为A组1.06±0.23mm,B组1.23±0.46mm,C组1.10±0.37mm,D组1.15±0.28mm,E组0.56±0.27mm。A、B、C、D各组间染料渗入长度无统计学差异(P>0.05),A、B、C、D各组与E组之间有统计学差异(P<0.05)。阳性组根管全部被染料染色,阴性组无染料渗入。结论:纤维桩成形钻对根尖微渗漏有一定影响,但与peeso钻相比无显著性差异。     

Influence of post placement in the fracture resistance of endodontically treated incisors veneered with direct composite

STATEMENT OF PROBLEM: Veneer preparations are considered to weaken endodontically treated maxillary incisors. Prefabricated posts have been controversially indicated to reinforce endodontically treated teeth before final restoration. PURPOSE: This in vitro study evaluated whether (1) veneer preparation in enamel or in enamel/dentin weakens endodontically treated maxillary incisors, (2) bonding of direct composite veneer restores the original strength of the unprepared teeth, and (3) use of prefabricated metal posts increases fracture resistance of prepared and restored teeth. MATERIAL AND METHODS: Ninety extracted human maxillary central incisors were submitted to conventional root canal treatment. Specimens were randomly divided into 8 experimental groups (veneer preparation in enamel or dentin with/without post and with/without direct composite veneer restoration) and a control group (n = 10). Specimens were loaded to fracture, and the data were analyzed statistically. RESULTS: Statistical analysis revealed that a conservative veneer preparation does not significantly reduce maxillary incisors' fracture resistance. For prepared incisors, bonding of direct composite veneer restored their original strength, and the use of posts did not increase their fracture resistance. CONCLUSION: Conservative veneer preparations involving enamel and enamel/dentin did not significantly reduce the fracture resistance of endodontically treated maxillary incisors. In addition, restoration of the intraenamel preparations with direct composite resulted in teeth more resistant to fracture than teeth having restorations in dentin. The use of posts did not improve fracture resistance of endodontically treated maxillary incisors reduced and veneered with direct composite.     

Parallel post-space preparation in different tooth types ex vivo: deviation from the canal centre and remaining dentine thickness

AIM: To determine the deviation of parallel-sided twist-drills during post-channel preparation and relate this to tooth type and position. METHODOLOGY: Human teeth with single root canals were selected: maxillary second premolars (group i); maxillary lateral incisors (group ii); mandibular canines (group iii); mandibular first premolars (group iv; all groups n = 16). The teeth were reduced to 17 mm length by sectioning the crown, and the root canals prepared and filled. Microradiographs were made in two directions. The teeth were individually embedded in a gypsum jaw and placed in a phantom head. Two operators performed parallel post-space preparation (12 mm length, 1.25 mm diameter) to the following protocol: gutta-percha removal with Gates Glidden drills numbers 2 and 3 and post-space enlargement with parallel drills numbers 3, 4 and 5, consecutively. Subsequently, microradiographs were re-exposed. The original and post-operative microradiographs were digitized and superimposed, and deviation of the post-space from the filled canal and remaining dentine thickness measured. RESULTS: Overall, the mean deviation was 0.07 mm to the mesial (95% CI: 0.01-0.12), and 0.27 mm to the buccal (95% CI: 0.18-0.35). Group ii had significantly more buccal deviation than other groups (P = 0.004-0.008). A remaining dentine thickness of <0.5 mm occurred 16 times in 14 teeth, and of <1 mm occurred 97 times in 52 teeth. CONCLUSIONS: Deviation during parallel post-preparation was common, predominantly in mesial and buccal directions, especially in maxillary incisors. This deviation increased the risk of perforation considerably.     

标准冠内固位体与碳纤维桩联合修复上颌第一前磨牙残根残冠的效果评价

目的探讨标准冠内固位体与碳纤维桩的联合应用在上颌第一前磨牙残根残冠修复治疗中的临床效果.方法临床选择49例残根残冠患者,共56颗患牙,经完善的根管治疗后,采用标准冠内固位体辅助碳纤维桩核冠固位的方法修复患牙,对临床疗效进行0.5～1年的追踪观察.结果 56颗患牙有52颗未见异常.1例修复体在修复后2个月后脱落.1例桥体瓷崩根折,2例患者基牙局部有龈炎.结论在严格选择适应证、注意临床和技工操作要点前提下,标准冠内固位体辅助碳纤维桩核冠固位的修复方法能够达到满意的修复效果.     

Root fracture in endodontically treated teeth related to post selection and crown design.

Standardized plastic analogues simulating an endodontically treated maxillary central incisor root were used to investigate the resistance to root fracture in endodontically treated teeth. Three different post and core systems were used: (1) cast post and core, (2) Para-Post Plus post, and (3) Flexi-Post post. The core build-up material selected in this study was Ketac Silver material, after which a crown preparation was made on each analogue. Two types of preparations were used: a wide chamfer margin (butt-joint) and a wide chamfer margin with a 1.0 mm circumferential bevel. An overcasting was fabricated and was permanently cemented on each preparation. Assemblies were subjected to an increasing lingual oblique force until fracture occurred. Results were tabulated using the analysis of variance (F test) and Student's t test. Beveled preparations with a concomitant final restoration provided a significant increased resistance to root fracture. Furthermore, vertical fracture occurred twice as often with nonbeveled preparations.