不同表面粒度车针预备所致玷污层对牙本质粘结强度的影响

目的：比较两种不同表面粒度的金刚砂车针进行牙体预备后对牙本质粘结强度的影响。方法：采用两种金刚砂车针与碳化硅砂纸对牙本质表面进行打磨预备后，分别选用全酸蚀粘结剂Single Bond及自酸蚀粘结剂iBond与树脂粘结，用慢速切割机片切牙齿，精细金刚砂车针修成沙漏状的粘接面积约0．8mm^2的样本，测试各个样本的微拉伸粘结强度。结果：全酸蚀粘结条件下，3组样本的粘结强度无显著差异，而在应用自酸蚀粘结剂时，粗粒度车针预备后的牙本质粘结强度明显低于经极细粒度车针或是碳化硅砂纸处理组（P〈0．05）。结论：采用极细粒度车针进行牙体预备可以有效增强牙本质与自酸蚀粘结剂间粘结强度。     

不同邻面抛光方法对牙釉质表面粗糙度及表面形貌的影响

目的：评价4种邻面抛光方法对邻面釉质表面粗糙度及显微形貌的影响,为邻面抛光方法的选择提供依据。方法：选择21颗离体牙前磨牙,沿颊舌面中线纵剖后获得邻面釉质试件42枚,再用自凝塑料包埋,暴露邻面釉质,用浮石粉抛光,并超声清洗。将42个试样均分为6组,分别作如下处理：A组空白对照,不做处理;B组：阴性对照,采用标准金刚砂车针切磨触点及其周围釉质,切磨后不抛光;其余4组为实验组,经标准金刚砂车针切磨后分别采用以下方法抛光：C组：极细粒度金刚砂车针抛光;D组：裂钻抛光;E组：矽粒子抛光;F组：彩虹抛光条抛光。之后用粗糙度仪测定釉面粗糙度,并进行扫描电镜观察。结果：标准金刚砂车针切磨后粗糙度大幅度增加（P〈0.05）,釉质表面发生明显条形凹陷性缺损;经4种方法抛光后,釉质表面粗糙度均有显著下降（P〈0.05）,显微形貌均较阴性组光滑,其中矽粒子抛光组可达到较空白对照组更为光滑的表面。结论：实验涉及的4种不同邻面抛光方法均有助于降低釉质切磨区域的表面粗糙度,但抛光效果存在差异;采用矽粒子抛光可完全抵消牙体预备时旋转器械对邻牙邻面的切磨作用,获得最为光滑的釉质表面。     

两种预备车针所致牙本质玷污层特点及其对通用型粘接剂粘接强度影响研究

目的 探究2种临床常用预备车针所致玷污层的特点及其对2种常用通用型粘接剂[Single Bond Universal(SBU)、All Bond Universal(ABU)]粘接强度的影响。方法 选取2020年6月至2021年3月于南京医科大学附属口腔医院外科门诊拔除的健康无龋阻生第三磨牙40颗,随机分为金刚砂组（使用金刚砂车针预备）和碳化钨钢组（使用碳化钨钢车针预备）,每组20颗。金刚砂组和碳化钨钢组各取14颗预备后的离体牙随机分为SBU亚组（使用SBU粘接剂并树脂分层固化）和ABU亚组（使用ABU粘接剂并树脂分层固化）,每亚组7颗,行微拉伸强度（粘接强度）测试并使用扫描电镜观察树脂牙本质粘接界面。金刚砂组和碳化钨钢组各取6颗预备后的离体牙随机分为玷污层亚组（不做处理）、SBU粘接亚组（仅SBU粘接剂粘接处理）和ABU粘接亚组（仅ABU粘接剂粘接处理）,每亚组2颗,使用扫描电镜观察牙本质玷污层及粘接剂处理后的牙本质面。结果 双因素方差分析结果显示,车针类型和粘接剂类型对粘接强度均有显著影响（F值分别为33.175、7.219,均P <0.05）,但两因素无显著交互作用（F=0...     

不同预备程序对基牙表面粗糙度的影响

目的：阐明不同基牙预备程序对基牙表面粗糙度的影响。方法：用粗砂轮在20个离体人磨牙邻面打磨出一平面，随机选择10个依次使用粗砂、标准砂、细砂、超细砂进口金刚砂车针打磨，其余10个分别使用国产车针和碳化硅砂石依次打磨，测定每个牙齿每次打磨后的表面粗糙度值（Ra、Ry值），对其结果进行统计学处理。结果：使用进口的粗砂车针、标准砂车针和国产车针组间以及碳化硅砂石与进口超细砂车针间的牙面Ra、Ry平均值均无显著统计学差异（P＞0.05），其余处理组间的Ra、Ry平均值均有非常显著的统计学差异（P＝0.0000）。结论：随着所用车针砂粒变细（从粗砂车针或标准车针到超细砂车针）牙齿表面粗糙度显著变小。普通国产车针与进口粗砂车针或标准车针预备后的牙齿表面粗糙度无显著差异别；碳化硅砂石可以达到与进口超细砂车针同样的磨光效果。     

根尖手术中超声骨刀对根尖切面粗糙度的影响

目的:比较超声骨刀、裂钻车针和金刚砂车针切除根尖后切面粗糙度的差异。方法:收集符合纳入标准的离体牙60个,随机分为3组(每组20个),分别使用超声骨刀、裂钻车针和金刚砂车针切除根尖3 mm,检测并记录切面粗糙度值Ra;体视显微镜下观察切面形态。结果:超声骨刀、裂钻车针和金刚砂车针3组的根尖切面粗糙度值Ra分别是(0.470±0.071)μm、(0.567±0.100)μm和(2.354±0.313)μm。超声骨刀组根尖切面最光滑,金刚砂车针组根尖切面最粗糙,结果存在显著性差异(P<0.01);而超声骨刀与裂钻车针组结果无统计学差异(P>0.05)。结论:与传统的裂钻和金刚砂车针相比,在根尖手术中使用超声骨刀进行根尖切除,根尖切面粗糙度较小,表面更加光滑。     

车针粒度对预备牙体与水门汀粘固强度的影响

目的：比较不同粒度金刚砂车针预备的牙面与聚羧酸锌水门汀的粘固强度。方法：分别采用4种不同粒度车针依次打磨4组牙本质片,测量其粗糙度,并采用扫描电镜观察;再将牙本质片与聚羧酸锌水门汀粘固,测试各组剪切强度。结果：4种粒度车针预备的牙面粗糙度间存在显著差异（P〈0.01）;聚羧酸锌水门汀与各组牙面的粘固强度间也存在显著差异（P〈0.05）。结论：随预备用车针粒度的减小,牙面粗糙度降低,聚羧酸锌水门汀与牙面的粘固强度也相应降低。     

Er：YAG激光切除牙根断面的扫描电镜观察

目的对Er：YAG激光切除的牙根断面进行扫描电镜研究,并通过对比超声金刚砂尖以及高速涡轮金刚砂车针切除牙根断面的不同表面状态,为Er：YAG激光应用于临床根尖切除术提供依据。方法将30颗上颌中切牙随机分为3组（Er：YAG激光切除组、超声金刚砂尖切除组、高速涡轮金刚砂车针切除组）,分别使用Er：YAG激光、超声金刚砂尖以及高速涡轮金刚砂车针在距离根尖3 mm处进行牙根切除。使用扫描电镜观察3组牙根断面残屑及玷污层、牙本质小管开放、裂隙以及器械切割痕迹情况。结果Er：YAG激光切除组和超声金刚砂尖切除组牙根断面有少量残屑、玷污层,并有牙本质小管开放;高速涡轮金刚砂车针切除组牙根断面有大量残屑及玷污层,没有牙本质小管开放。高速涡轮金刚砂车针切除组中能看到大量裂隙出现,超声金刚砂尖切除组中可见裂隙出现,而Er:YAG激光切除组中几乎没有裂隙出现。高速涡轮金刚砂车针切除组和超声金刚砂尖切除组牙根断面的表面粗糙并有明显切割痕迹,而Er：YAG激光切除组牙根表面没有切割痕迹,较为平滑。结论Er：YAG激光应用于根尖切除具有一定的优势,其牙根断面组织形态学方面的表现明显优于超声金刚砂尖和高速涡轮金刚砂车针。     

超声预备牙体表面的三维形貌分析

目的:了解超声制备牙体的表面三维形貌特征.方法:将纳入的10颗上颌前磨牙,按照临床烤瓷冠牙体预备要求及步骤,完成牙体初步预备,形成的浅凹形肩台,采用分半预备,牙体一半(对照侧)使用常规马尼车针制备肩台及抛光,另一半(超声处理侧)依次使用超声预备车针PM1/PM2/PM4制备肩台及抛光,完成肩台边缘线,使肩台均匀下移约0.5 mm.通过电镜及白光干涉仪观察、记录表面三维粗糙度、表面偏态,采用SPSS 13.0软件包对所得的各组数据进行独立样本t检验分析.结果:扫描电镜及白光干涉仪均观察到,对照组表面旋转器械的砂石磨削痕迹明显;与处理组相比,呈现更细密的波纹状,而处理组波纹痕迹的上表面被较平整的小平面覆盖;超声处理组与对照组相比,处理组表面粗糙度以及表面偏态均显著小于对照组(P=0.011,P=0.000).结论:超声预备的牙体表面形貌较常规旋转器械更平整、光滑.     

不同粒度车针牙体预备对基底冠适合性影响的研究

目的：比较不同粒度金刚砂车针预备的牙体对烤瓷修复体基底冠适合性的影响。方法：采用4种不同粒度车针对预备牙面进行打磨，根据最终使用车针型号的不同将离体牙试件分为4组，分别制取印模并制作基底冠。采用玻璃离子水门汀将基底冠粘固在牙体上，评价其微渗漏情况和适合性。结果：预备体表面采用车针打磨至不同水平的各组牙试件，经玻璃离子粘固后的微渗漏等级之间存在显著性差异（P〈0．05），各组基底冠与牙体之间的粘固剂厚度也存在显著性差异（P〈0．01）。结论：随车针粒度的减小，牙预备体与镍铬合金基底冠之间的适合性逐渐提高。     

空气喷磨对乳牙树脂充填微拉伸强度的影响

目的：研究空气喷磨对乳牙树脂充填微拉伸强度的影响,为该技术的临床应用提供依据。方法24颗离体乳磨牙切除冠部釉质暴露牙本质后,随机分为2组,分别用50μm氧化铝微粒空气喷磨(空气喷磨组)和金刚砂车针预备(金刚砂车针组)。每组抽取2个样本牙,1个样本牙直接扫描电镜观察,另外1个进行酸蚀后行扫描电镜观察。余留样本牙复合树脂充填后制成试件,采用微拉伸技术,测试试件断裂时的最大应力。结果空气喷磨组的微拉伸强度为(24.470±3.194) Mpa,高于金刚砂车针组(22.294±2.268) Mpa,差异有统计学意义(P<0.05)。扫描电镜观察：涡轮机金刚砂车针预备后酸蚀的牙本质表面呈浅坑状形态,空气喷磨后酸蚀呈规则的蜂窝状。结论空气喷磨技术可提高乳牙复合树脂充填的微拉伸强度。     

Surface roughness and wettability of enamel and dentine surfaces prepared with different dental burs

The aim of dental adhesive restorations is to produce a long lasting union between the restoration and the tooth structure. This bond depends on many variables including the geometry of the preparation and the type of bonding agent or luting cement. It is therefore suggested that the topography of the tooth surface may influence the wettability and the bonding quality of adhesive systems. This study measured the surface roughness and wettability of enamel and dentine after preparation with different dental burs. The mesial and distal surfaces of 15 extracted sound human premolar teeth were prepared with a tungsten carbide crown bur, a diamond bur and a tungsten carbide finishing bur and finished in enamel or dentin, respectively. The prepared surfaces were analysed with a surface profilometer and scanning electron microscopy (SEM). The contact angle of distilled water on each of the prepared surfaces was used as the measure of wettability. The differences in average surface roughness (Ra) were significant between the rotary instrument groups, as revealed by a two-way ANOVA test. No differences were detected between enamel and dentine surfaces prepared with the same type of dental bur. The smoothest surfaces were those completed with tungsten carbide finishing burs. The diamond bur preparations were intermediate in the roughness assessment and the tungsten carbide crown burs gave the roughest surfaces. There were no significant differences in the contact angle measurements for the various groups. It was concluded that the surface roughness of enamel and dentine prepared by different rotary instruments had no significant influence on the wettability of distilled water on these surfaces.     

SEM evaluation of the hybrid layer after cavity preparation with Er:YAG laser

This study compared the thickness of the hybrid layer formed using Scotchbond Multi-Purpose Plus, Single Bond 2, Prime & Bond 2.1 and Xeno III on a dentin surface prepared with a diamond bur in a high speed handpiece or prepared with an Er:YAG laser used with two parameters of pulse energy (200 and 400 mJ) and two parameters of frequency (4 and 6 Hz). Flat dentin surfaces obtained from 20 human third molars were treated with the two methods and were then prepared with the dentin adhesive systems according to the manufacturers' instructions. After a layer of composite was applied, the specimens were sectioned, flattened, polished and prepared for Scanning Electronic Microscopy observation. Five different measurements of the hybrid layer thickness were obtained along the bonded surface in each specimen. The results were statistically analyzed using Analysis of Variance and Student-Newman-Keuls tests (p < or = 0.05). When analyzing the hybrid layer thickness and comparing the cavity preparation method, four groups were formed: Group I (diamond bur) > Group II (Laser 200 mJ/4 Hz) = Group III (Laser 200 mJ/6 Hz) > Group IV (Laser 400 mJ/4 Hz) > Group V (Laser 400 mJ/6 Hz). When comparing the dentin adhesive systems, there were no statistically significant differences. These results showed that the four tested dentin adhesive systems produced a 2.90 +/- 1.71 microm hybrid layer in dentin prepared with a diamond bur. This hybrid layer was regular and routinely found. In the laser groups, the dentin adhesive systems produced hybrid layers ranging from 0.41 +/- 1.00 microm to 2.06 +/- 2.49 microm, which were very irregular and not routinely found. It was also concluded that the Er:YAG laser, with the parameters used in this experiment, has a negative influence on the formation of a hybrid layer and cavity preparation methods influence formation of the hybrid layer.     

Effect of bur type on microtensile bond strengths of self-etching systems to human dentin

PURPOSE: To compare the microtensile bond strength (microTBS) of five adhesives to human dentin prepared with 600-grit SiC abrasive paper (SiC), a diamond rotary instrument, or a carbide bur. The null hypothesis was that different cavity preparation instruments do not affect adhesion of resin adhesives. MATERIALS AND METHODS: Human molars (n = 45) were randomly divided into three groups according to surface treatment. Each group was bonded using a total-etch adhesive (Single Bond, 3M ESPE), one of three self-etching primer systems (Clearfil SE Bond or ABF, Kuraray; Imperva Fluorobond, Shofu), or a self-etching adhesive (One-Up Bond F, Tokuyama). A 4-mm composite crown was built over the bonded surface. Specimens were stored in water for 24 h at 37 degrees C. They were sectioned into 0.7-mm-thick slabs, trimmed to a cross-sectional area of 1 mm2, and loaded to failure at a crosshead speed of 1 mm/min using a tabletop tester (EZ-Test, Shimadzu). Microtensile bond strength data were analyzed using analysis of variance and Fisher's PLSD test. RESULTS: Surface preparation using a carbide bur generally yielded higher bond strengths than preparation using either a diamond rotary instrument or SiC abrasive paper. SE Bond had the highest mean microTBS of the five adhesives tested. CONCLUSION: Resin-dentin bond strengths can be affected by the type of instrument used to prepare the tooth. Specifically, higher bond strengths might be achieved by using carbide burs rather than diamond cutting instruments.     

A micro-computed tomographic evaluation of apical root canal preparation using three instrumentation techniques

Aim  To investigate the morphological changes in the apical third of the root canal after preparation with three techniques.
Methodology  Forty molar teeth were scanned using micro-computed tomography before and after instrumentation with: Group 1 – stainless steel K-files using the balanced force technique; Group 2 – stainless steel K-files (balanced force) and then refining the apical preparation with the equivalent size 0.04 taper FlexMaster instrument; Group 3 – a hybrid ProTaper/FlexMaster (ProFile for sizes 45 and 60) sequence. Eight canals were excluded because of artefacts in the images or unnegotiable blockages leaving 110 canals that could be analysed. Apical root canal preparation was evaluated with respect to the amount of dentine removed, canal roundness, transportation and how the dimensions of the prepared apical root canal correlated with those of the final instrument used.
Results  The median apical preparation sizes for the three groups respectively were: 30, 30 and 40. Despite the larger size and less experienced operator, the volumetric change (the amount of dentine removed) in canals prepared with a hybrid rotary nickel–titanium instrumentation technique remained small and, a more rounded preparation ( P  < 0.001) that closely matched the final instrument dimensions ( P  < 0.001) was produced. There was a trend for less canal transportation using rotary nickel–titanium instruments.
Conclusions  Stainless steel hand preparation was not conservative of apical dentine. When used correctly, even by less experienced operators, rotary nickel–titanium instruments were able to precisely 'machine' a canal to larger apical sizes with minimal risk of iatrogenic damage.     

Advancements in dental preparation technique (literature review)

This paper has reviewed the literature on the methods of cavity preparation. The different methods are summarised in Table 1. Nowadays rotary instruments are accepted as standard for cavity preparation. The limitation of using a rotary instrument is the iatrogenic damage to adjacent teeth. Therefore some of the hand instruments remained an essential part of quality restorative dentistry. In order to reduce iatrogenic injury oscillating instruments had been developed. The oscillating instruments change the rotary movement into an oscillating movement and copy the shape of the working tip through an abrasive medium to the tooth surface. The abrasive medium is generally diamond. A new possibility in tooth preparation is the Er:YAG laser. It can be used for both cavity preparation and caries removal. The chemo-mechanical caries removal means the selective chemical softening is followed by the mechanical removing of carious dentin.     

Bonding properties of universal adhesives to root canals prepared with different rotary instruments

Statement of problem

Preparation of coronal dentin by using a diamond rotary instrument usually results in higher bond strength values than preparation with tungsten carbide burs, but information is lacking about the influence of rotary instruments on root canals before the bonding of fiber posts.

不同器械及预备方法对单根管内感染物清除效果的比较

目的:比较分析不同器械及方法机械预备后对单根管内细菌感染物的清除效果及其影响因素.方法:选择45 个慢性根尖周炎的单根管患牙,随机分为3 组,每组15 个患牙,A组:手用不锈钢锉、步退法预备根管;B组:HERO 642镍钛锉、标准冠下法预备根管;C组:Mtwo镍钛锉、改良冠向下法预备根管.各组预备过程中用无菌生理盐水冲洗,分别于预备前、预备后根管内取样、接种、培养,检测根管内细菌种类及数量的变化.结果: 3 组器械及方法机械预备后均可使根管内的细菌种类及数量明显减少(P<0.01),其中手用不锈钢根管锉、步退法及Mtwo旋转镍钛锉、改良冠向下法预备后根管内细菌的减少量均大于HERO 642旋转镍钛锉、标准冠下法,且差异有显著性(P<0.05),手用不锈钢根管锉、步退法预备后根管内细菌的减少量大于Mtwo旋转镍钛锉、改良冠向下法,但差异无显著性(P>0.05).结论:机械预备可以大大减少根管内细菌量,但不能达到完全无菌,旋转镍钛器械、标准冠下法在提高根管内感染清除能力并无明显优势,机械预备应配合化学预备以提高根管治疗的成功率.     

Effects of rotary instrumentation and different etchants on removal of smear layer on human dentin

STATEMENT OF PROBLEM: Various methods of rotary preparation and conditioning of teeth affect surface topography and may affect the retention of dental restorations. PURPOSE: This study microscopically evaluated dentin surfaces prepared by different rotary instruments and etched using several types of acid etchants that have been deemed suitable dentin conditioners. MATERIAL AND METHODS: Occlusal surfaces of 35 extracted human molars were ground wet with 320-grit silicon carbide paper to the depth of the central groove and then prepared with diamond (n = 5) and finishing burs (n = 30). Five specimens from each group were used for SEM evaluation of mechanical preparation effects. Dentin specimens (n = 5) prepared with finishing burs were then etched with 1 of 5 etchants (25% polyacrylic acid, 10% phosphoric acid, 10% citric acid, 20% lactic acid, or 32% phosphoric acid) for 10 seconds. Specimens were critical-point dried and freeze fractured for SEM analysis. RESULTS: Diamond rotary instruments created more undulating surfaces than finishing burs. Fine grooves were observed running perpendicular to undulations and parallel to the direction of instrument rotation. Specimens prepared with finishing burs exhibited a smooth surface interrupted by only a slight granularity. The amorphous smear layer was partially removed after the application of 25% polyacrylic acid (pH 1.53), but all dentinal tubules contained plugs. The number of dentin tubules containing plug material and the amount of material in the tubules decreased noticeably with 10% phosphoric acid (pH 0.86), and the dentin surface had an appearance similar to the specimen etched with 10% citric acid (pH 1.70). The surfaces treated with 20% lactic acid (pH 1.40) produced a clearly etched surface with minimal demineralization. Etching of dentin with 32% phosphoric acid (pH 0.16) revealed significant changes in dentin with the evidence of increased tubule diameter. CONCLUSION: Differences related to the method of instrumentation were found in the surface characteristics of dentin. The degree of smear layer removal was related to the pH of the acid etchant.     

IN VITRO EVALUATION OF ROOT CANAL PREPARATION USING OSCILLATORY AND ROTARY SYSTEMS IN FLATTENED ROOT CANALS

Objective:

The aim of this study was to evaluate the biomechanical preparation of flattened root canals using the following systems: Endo-Eze AET stainless steel oscillatory instruments (Ultradent) and RaCe rotary NiTi instruments (FKG Dentaire).

Materials and Methods:

Twenty extracted human mandibular incisors were randomly assigned to two groups: Group 1 - Instrumentation with oscillatory Endo-Eze AET files (oscillatory technique); Group 2 - Instrumentation with rotary NiTi RaCe files (rotary technique). The teeth were decoronated, had their apices and coronal openingssealed with sticky wax and were embedded in crystal-clear orthophtalic polyester resin. The roots were sectioned transversally with diamond discs at 10 mm (middle third) and 5 mm (apical third) from the apex and the segments were reassembled for instrumentation. The sections were photographed before and after root canal instrumentation and evaluated with respect to whether the original root canal shape was modified by instrumentation. To evaluate the differences in the root canal shape before and after biomechanical preparation, scores were given regarding the instruments touch on the intracanal walls.

Results:

In middle third of the root canals instrumented with the rotary system, there was a change in the original canal anatomy (p<0.05), with formation of a protuberance in the mesiodistal direction. This protuberance did not occur when the oscillatory instrumentation was used. The oscillatory system had better results in the middle and apical thirds as evaluated by Dunn’s multiple-comparison test (p>0.05).

Conclusion:

Under the tested conditions, Endo-Eze oscillatory system yielded the instrumentation of all flattened root canal walls, maintaining the canal original shape throughout the biomechanical preparation, and was more effective than RaCe rotary system.