上颌第一前磨牙根管形态的锥形束CT研究

目的利用CBCT评估上颌第一前磨牙根管解剖形态。方法收集因种植手术前评估,正畸治疗前评估,复杂疑难根管治疗等原因拍摄的CBCT 710例,根据样本纳入标准得到404例双侧CBCT图像,记录患者的姓名,性别,年龄,牙位,牙根和根管数目,牙根弯曲方向和根分叉的位置。结果上颌第一前磨牙以单根牙和多根牙多见,三根牙最少见,单根牙发生率为65.1%,双根牙发生率为34.7%,三根牙发生率为0.2%,有2例左侧颊根分为两根,为三根牙。单根牙和双根牙在男女性别间的发生率无统计学差异,根管类型中14.7%有1个根管为Ⅰ(1-1)型,85.1%为复杂的两根管类型(Ⅱ型到Ⅶ型及2-1-2-1型),只有0.2%有三根管为Ⅷ型。上颌第一前磨牙牙根弯曲的发生率为38.1%。根据弯曲方向分为5种类型,颊侧弯曲22.7%,舌侧弯曲17.3%,近中弯曲11.6%,远中弯曲42.1%,S形弯曲6.2%。上颌第一前磨牙牙根分叉的发生率为34.9%,根据分叉的部位分为根冠1/3、根中1/3、根尖1/3分叉,发生率为31.6%,44.7%,23.8%。结论上颌第一前磨牙多为单根牙,而且多为单根牙双根管,单根牙的根管形态多样,牙根多向远中弯曲,牙根分叉位于牙根中段。     

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

目的:探讨上颌前磨牙桩道预备后剩余根管壁厚度及对抗折强度的影响。方法:对100颗单、双根管上颌 前磨牙,用1#～5#P型钻进行桩道预备,用光学显微镜分别测量各组牙冠方和根方剩余根管壁厚度,并观察桩道预 备对抗折强度的影响。结果:单根管上颌前磨牙,1#～2#P型钻预备后,各壁剩余厚度均大于1mm;而对于双根管 上颌前磨牙,1#～3#P型钻预备后,各壁剩余厚度均大于1mm。另外,1#～5#P型钻预备后,牙根抗折强度逐渐变小 (P 0.01),且相同直径器械预备后,双根管抗折强度大于单根管(P 0.01)。结论:用P型钻预备桩道时,单根 管牙最大可用2#P型钻预备,双根管牙最大可用3#P型钻预备,且剩余牙质的量与牙齿的抗折强度成正相关。     

上颌第一前磨牙三个根管一例

上颌第一前磨牙多为单根管或双根管,3个根管较少见.现将河南省安阳市口腔医院收治的一例上颌第一前磨牙3个根管病例报告如下: 患者,女性,47岁,2009年4月28日以"左上后牙进食时疼痛1个月"就诊.临床检查:左侧上颌第一前磨牙远中邻(牙合)面龋,探诊疼痛,叩诊(±),有冷热刺激痛.     

离体上颌第二前磨牙根管和牙根情况的研究

目的观察上颌第二前磨牙的牙根及根管形态。方法213颗离体的上颌第二前磨牙，对牙齿进行近远中向X线照像，并从根中1／3横断探测确实，Vertueei’s分类法对根管系统进行记录。结果185颗牙是单根(87％)，28颗牙是双根(13％)，而单根牙中最多的是1个根管[Type Ⅰ(1)]，占牙齿总数的43％，其次是单根双管TypeⅡ(2-1)，即颊舌2个根管，至根尖又合并成一个根尖孔，占牙齿总数的35％。结论上颌第二前磨牙主要是单根，单个根尖孔的发生率高(78％)。     

422颗上颌第一前磨牙牙根及根管解剖形态的观察

目的:了解上颌第一前磨牙的牙根和根管形态,为临床治疗提供解剖学依据.方法:收集422颗上颌第一前磨牙.按性别分组,统计分析各牙根形态出现率;采用透明牙技术观察分析根管形态,根据Vertucci分类法,统计分析各根管形态的出现率;采用SPSS11.5软件包对数据进行X2检验.结果:(1)422颗标本中,单根牙占57.36%,双根牙占41.47%.三根牙占1.18%.男性组分别为33.58%、62.68%和3.73%.女性组分别为66.67%、33.33%.没有三根牙.2组间有显著性别差异(P＜0.01).(2)415颗透明牙标本中,共观察到9种根管形态.Ⅰ型占10.12%,Ⅱ型占10.60%,Ⅲ型占6.02%.Ⅳ型占56.63%,Ⅴ型占12.05%,Ⅵ型占1.93%.Ⅶ型占0.72%,Ⅷ型占1.45%,Ⅸ型占0.48%.单根管(Ⅰ型)占10.12%.双根管(Ⅱ-Ⅶ型)占87.95%,三根管(Ⅷ,Ⅸ型)占1.93%.结论:上颌第一前磨牙牙根形态多样并有显著性别差异.而且根管形态类型复杂.充分了解其解剖形态.对临床治疗具有重要意义.     

上颌第一前磨牙根尖区根管横截面形态的研究

目的 研究上颌第一前磨牙根尖区根管横截面的形态.方法 选择15个上颌第一前磨牙(单根牙11个,双根牙4个),利用Isomet低速金刚砂切片机,在距解剖根尖1、2、3、4、5、6 mm处垂直牙体长轴切割.然后在牙科手术显微镜下,利用Photoshop CS 8.0软件测量各截面根管的颊舌径和近远中径,按标准记录根管横截面的形态.结果 共获得切片111个,根管共138个,其中长椭圆形根管发生率为42.0%.单根管牙的颊舌径大于近远中径,以长椭圆形根管形态为主,其发生率向根尖降低;双根牙的颊根管颊舌径大多小于近远中径,但腭根管颊舌径均大于近远中径,长椭圆形根管发生情况更复杂.结论 上颌第一前磨牙根尖区根管横截面形态复杂,可能影响根管治疗的质量.     

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。     

上颌前磨牙根管变异及其与上颌窦关系的锥形束CT研究

目的:利用锥形束CT研究上颌前磨牙牙根及根管系统解剖形态,为临床提供影像学依据。方法:选取720例成人患者（18~67岁）的锥形束CT扫描图像,按年龄分为5组：18~28岁、29~38岁、39~48岁、49~58岁及>58岁组,分析上颌前磨牙牙根及根管数、根管类型、两根管口间距离、根管弯曲度、根尖到上颌窦底距离、左右同名牙的对称性等及与年龄的关系。采用SPSS21.0软件包对数据进行统计学处理。结果:上颌第一前磨牙多为双根管（89.72%）,根管类型以Ⅳ型最常见（57.78%）。上颌第二前磨牙单根管发生率（53.06%）略高于双根管（46.94%）,根管类型以I型（53.06%）为主。左右同名牙牙根及根管数目多为对称分布。上颌前磨牙单根、双根管检出率随年龄变化而变化,两根管口间距离与根管类型关系密切。上颌第一、第二前磨牙颊舌向弯曲的根管检出率分别为32.53%和21.50%,存在S形复杂弯曲根管。16.69%的上颌第二前磨牙与上颌窦为关系密切型（d≤0.05 mm）。结论:上颌前磨牙牙根及根管解剖结构复杂,左右同名牙呈对称性。根管形态、结构和类型存在增龄性变化,根管弯曲情况复杂,牙根与上颌窦关系密切。     

下颌前磨牙牙根形态和根管系统的锥形束CT研究

目的采用锥形束CT(Cone-beam computed tomography,CBCT)研究下颌前磨牙牙根及根管系统解剖形态特征。方法回顾148例患者288颗下颌第一前磨牙和218颗下颌第二前磨牙的CBCT影像,分析牙根和根管系统形态,采用Vertucci等提出的分类法对根管构型进行分类。结果 288颗下颌第一前磨牙单根牙285颗,双根牙2颗。三根牙1颗;根管Ⅰ型占77.78%,Ⅱ型0.34%,Ⅲ型2.08%,Ⅳ型0.69%,Ⅴ型14.58%,Ⅶ型1.04%,Ⅹ型0.69%,C型2.78%。218颗下颌第二前磨牙全部为单根;根管Ⅰ型占98.17%,Ⅴ型占1.83%。结论下颌前磨牙大多数是单根单根管。下颌第一前磨牙根管系统具有较大的变异性。下颌第一前磨牙多根管类型主要是Ⅴ型,C型根管的检出率也较高。而下颌第二前磨牙多根管的发生率远低于下颌第一前磨牙。多根管的分歧发生在根中或根尖1/3处。CBCT可用于下颌前磨牙复杂根管形态的评价。     

95个前磨牙牙根解剖形态的研究

目的:了解前磨牙根部解剖结构特点,为临床治疗提供参考.方法:收集有临床记录的人前磨牙95个,用立体显微镜观察牙根颈部、根中1/2、距根尖2 mm处横截面结构特征,并结合X线片特点、离体牙相片进行分析.结果:95个前磨牙总体上单根牙所占比例较高,但上颌第一前磨牙双根发生率在40%左右.除下颌第二前磨牙外,即使是单根牙,双根管的发生率也超过1/3,还有个别三根管的情形.根管内部结构复杂,除了常见的哑铃形,还可见C形根管.龋、楔形缺损等牙体病损,尤其在牙颈部由于第三期牙本质的沉积,会使相应部位的根管狭窄,甚至改变根管走向.结论:前磨牙根部解剖结构复杂而且较多受临床病理情况的影响,应引起临床医生的注意.     

Dental specialty,career preferences and their influencing factors among final year dental students in Saudi Arabia

Objective

The purpose of this study was to investigate evolving trends in dental post graduate specialty preferences and career aspirations among final year dental students in Saudi Arabia.

Physicochemical and mechanical characterization of a fiber-reinforced composite used as frameworks of implant-supported prostheses

ObjectivesTo characterize the physicochemical and mechanical properties of a milled fiber-reinforced composite (FRC) for implant-supported fixed dental prostheses (FDPs).MethodsFor FRC characterization, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction, Fourier-transformed infrared spectrometry, simultaneous thermogravimetric analysis and differential scanning calorimetry were performed. For fatigue testing, 3-unit FRC frameworks were fabricated with conventional (9 mm² connector area) and modified designs (12 mm² connector area and 2.5 mm-height lingual extension). A hybrid resin composite was veneered onto the frameworks. FDPs were subjected to step-stress accelerated-life fatigue testing until fracture or suspension. Use level probability Weibull curves at 300 N were plotted and the reliability for 100,000 cycles at 300, 600 and 800 N was calculated. Fractographic analysis was performed by stereomicroscope and SEM.ResultsThe FRC consisted of an epoxy resin (∼25%) matrix reinforced with inorganic particles and glass fibers (∼75%). Multi-layer continuous regular-geometry fibers were densely arranged in a parallel and bidirectional fashion in the resin matrix. Fatigue analysis demonstrated high probability of survival (99%) for FDPs at 300 N, irrespective of framework design. Conventional FDPs showed a progressive decrease in the reliability at 600 (84%) and 800 N (19%), whereas modified FDPs reliability significantly reduced only at 800 N (75%). The chief failure modes for FRC FDPs were cohesive fracture of the veneering composite on lower loads and adhesive fracture of the veneering composite at higher loads.SignificanceMilled epoxy resin matrix reinforced with glass fibers composite resulted in high probability of survival in the implant-supported prosthesis scenario.     

牙菌斑液对牙釉质矿物的饱和程度与龋活动性的关系

为了解菌斑液对牙齿矿物饱和度随糖漱口的变化，以及与龋活动性的关系，作者选择２２例年龄相同的大学生，按龋齿情况，将其分为３组。第１组无龋（无龋组），第２组ＤＭＦＳ大于１０但无活动性龋（普通龋组），第３组ＤＭＦＳ大于１０且有活动性龋（活动性龋组），测定各受试者在静止时、用蔗糖液漱口后３ｍｉｎ和７ｍｉｎ时的菌斑液中有机酸、ｐＨ值、钙离子活度（有效离子浓度）和无机成分的含量，并计算对于釉质矿物的饱和度。结果表明，糖漱口之后菌斑液乳酸浓度升高、ｐＨ值降低、总钙和离子钙浓度增加。活动性龋组的菌斑液在糖漱口后ｐＨ值和饱和度降低的幅度明显大于无龋组和普通龋组。结论：牙菌斑液对牙齿矿物的饱和度是指示个体接受致龋食物后牙齿脱矿倾向的敏感指标。     

饰瓷对磨牙e.max双层全瓷冠断裂类型的影响

目的：通过抗折破坏实验研究饰瓷对磨牙e.max双层全瓷冠断裂强度和断裂类型的影响,为减少临床双层全瓷修复体崩瓷提供实验依据。方法：制作单层全瓷冠（IPS e.max Press）和双层全瓷冠（IPS e.max Press/Ce-ram）共40个（每组20个）,粘接于树脂代型后进行抗折破坏实验并记录断裂强度值;体视显微镜和扫描电子显微镜下观察断裂类型;能谱分析饰瓷-核瓷界面化学元素构成。结果：单层全瓷冠断裂强度值[（2665.4±759.2）N]与双层全瓷冠[（1431.1±404.3）N]间差异有统计学意义（P=0.000）。饰瓷内部及饰瓷-核瓷界面缺陷催生裂纹造成饰瓷崩裂是双层全瓷冠断裂的主要模式。结论：饰瓷对磨牙e.max双层全瓷冠断裂强度和断裂类型均有影响;饰瓷内部及饰瓷-核瓷界面缺陷是全瓷冠断裂的主要原因,提高饰瓷断裂强度及减少界面缺陷可减少因崩瓷造成的修复体失败。     

Comparative study on the effect of ultrasonic instruments on the root surface in vivo

The present study was designed to investigate the effectiveness of different ultrasonic instruments on the root surface. Fourteen patients with 35 single root teeth designated for extraction were recruited to the present study. Teeth were assigned to four experimental groups: group 1, piezoelectric ultrasonic device; group 2, magnetostrictive ultrasonic device; group 3, hand instrumentation; and group 4, untreated teeth (control). After instrumentation, the teeth were extracted and the presence of residual deposits (roughness and root surfaces characteristics) were analyzed. The results showed that residual deposits were similar in all tested groups: piezoelectric, 8.7%; magnetostrictive, 9.7%; hand instrumentation, 11.1% and control, 76.4%. There were statistically significant differences between control and all the experimental groups (p < 0.0001). With respect to roughness parameters evaluation, R_a and R_z of the roots treated with the different instruments showed a similar pattern (p > 0.05), but for R_t and R_y, a significant difference was observed (p < 0.05) among hand instrumentation and ultrasonic devices. SEM analysis revealed a similar root surface pattern for the ultrasonic devices, but curettes showed many instrumental scratches, deep gouges, and a relatively large amount of dentin was removed. Within the limits of the study, although the instruments produced similar results, root surfaces instrumentated with curettes were rougher and had more root surface tissue removed than with the ultrasonic device.     

BLB种植体的临床应用及近期疗效观察

目的：评估BLB种植体的近期临床应用效果。方法：2003年2月-2005年12月，在北京通州区潞河医院口腔科用BLB种植体进行延期种植，共47枚，采用一期埋入、二期暴露的潜入式方法，全部为金属烤瓷冠修复，临床随诊观察半年至3年。结果：随诊期间无一例种植体脱落，4例因中央螺丝松动致修复体松动，2例发生种植体周围炎；种植体周围牙槽骨水平吸收小于0．2mm／年。结论：BLB种植体适合于常见牙列缺损的延期种植修复，近期疗效可靠     

INFLUENCE OF MICROLEAKAGE,SURFACE ROUGHNESS AND BIOFILM CONTROL ON SECONDARY CARIES FORMATION AROUND COMPOSITE RESIN RESTORATIONS: AN IN SITU EVALUATION

This study was carried out to evaluate in situ the influence of microleakage, surface roughness and biofilm control on caries formation around composite resin restorations. During 28 days, 12 volunteers wore palatal devices containing bovine enamel slabs restored with composite resin. Restorations were made without leakage, when the adhesive system was applied, or with leakage, when adhesive system was omitted. Half of the restorations in each group were finished and the remaining were finished and polished. In one side of the palatal device, biofilm was left to accumulate over the restored slabs, and in the other side dental slabs were brushed, to allow biofilm removal. There was an extraoral application of 20% sucrose solution (8x/day) over the enamel slabs. The formation of caries lesions (white spots) was evaluated by visual inspection under stereomicroscopy. Additionally, the dental slabs were sectioned and observed under polarized light microscopy. Data were submitted to Kruskal-Wallis test and Spearman''s correlation test at 5% significance level. Polishing and bonding were not significant factors regarding white spot formation (p>0.05). Biofilm control (brushing) was associated with reduction of caries formation close to the restorations (p<0.01). Polarized light microscopy confirmed the visual inspection findings. These results suggest that while microleakage and surface roughness did not influence caries lesion formation, biofilm control may prevent the enamel demineralization.     

SEALING ABILITY OF CEMENTS IN ROOT CANALS PREPARED FOR INTRARADICULAR POSTS

This research evaluated the sealer ability of 2 temporary filling materials (white Cimpat and IRM) and 1 restorative cement (glass ionomer), in canals prepared for root posts. Sixty human palatal roots of maxillary first molars were used. They were divided into 3 groups, according to the cements used: Group I (Cimpat), Group II (IRM) and Group III (glass ionomer). The roots were rendered impermeable, filled with the respective cements and soon after immersed into 0.2% Rhodamine B dye and maintained for 72 hours in an oven for 37°C. Microleakage was measured with a light microscope, cutting the roots longitudinally in buccolingual direction. The results showed that Group I presented significantly more leakage than Groups II and III, which were not significantly different from each other.