Quantitative comparison of calcium hydroxide removal by endoactivator, ultrasonic and protaper file agitation techniques: An in vitro study

Calcium hydroxide (CH) dressing residues can compromise endodontic sealing. This study aimed to evaluate the amount of remaining CH in root canals after mechanical removal by four groups of irrigation techniques including needle irrigation only, ProTaper file, EndoActivator, and ultrasonic file. Fifteen extracted single-rooted teeth were collected and used for all four groups. The samples were firstly prepared by ProTaper rotary instruments, and then sectioned longitudinally through the long axis of the root canals, followed by final reassembling by wires. CH was kept in the canals for 7 days setting. The removal procedure began with 5 mL of 2.5% sodium hypochlorite (NaOCl) followed by 1 mL of 17% ethylenediaminetetraacetic acid and a final irrigation with 5 mL of 2.5% NaOCl solution for all groups. No additional agitation of the irrigant was performed in group 1, while agitation for 20 s between irrigants was done with F2 ProTaper rotary file in group 2, EndoActivator with tip size 25/.04 in group 3 and by an ultrasonic file 25/.02 in group 4. The total activation time was 60 s. The roots were then disassembled and captured by digital camera. The ratio of CH coated surface area to the surface area of the whole canal as well as each third of the canal was calculated. The data were statistically analyzed by one-way ANOVA using post hoc Tukey test. Results showed that none of the four techniques could remove all CH. No significant difference was found between EndoActivator and ultrasonic techniques. However, they both removed significantly more CH than ProTaper and needle irrigation (P=0.0001). In conclusion, the sonic and ultrasonic agitation techniques were more effective in removing intracanal medicaments than the ProTaper rotary file and needle irrigation in all thirds of the canal.     

In vitro Study of Apically Extruded Debris and Irrigant Following the Use of Conventional and Rotary Instrumentation Techniques

The complete preparation of the root canal space is one of the most important stages in endodontic treatment. While the root canal space is being prepared, debris, irrigant, necrotic tissue or bacteria may be extruded into the periapical region, leading to periapical inflammation and postoperative flare-ups. The aim of this study is to compare in vitro the amount of debris and irrigant extruded apically after a root canal preparation, using two instrumentation techniques--the conventional hand ＂step back＂ technique with SS K-files and the engine-driven ＂crown down＂ technique with Ni-Ti K3 files. Two groups of 20 extracted teeth with single canals were used. In group 1 （10 teeth）, the root canals were instrumented using a ＂step back＂ technique and stainless steel K-files. In group 2 （10 teeth）, the root canals were instrumented using a ＂crown-down＂ technique and nickel-titanium K3 rotary instruments. Debris and irrigant extruded from the apical foramen during instrumentation were collected into vials and the amounts were measured. The debris extruded through the apical foramen in group 1 （K-files） was 0.400 mg and in group 2 （K3 files）--0.225 mg. The volume of the extruded irrigant was 0.443 mL in group 1 and 0.247 mL in group 2. The time taken for instrumentation was 13 min for the step back technique and 8.7 min for the crown-down technique. There is a significant difference in the amount of debris and irrigant produced between the two groups. During biomechanical preparation of the root canal space, debris and irrigant were extruded through the apical foramen by both instrumentation techniques.     

Efficacy of solution form of ethylenediaminetetraacetic acid on removing smear layer of root canal at different exposure time In Vitro

Summary： This study was aimed to evaluate the effectiveness of solution form of 17% ethylenediaminetetraacetic acid （EDTA） on removing smear layer of root canals at different exposure time periods and to provide scientific basis for EDTA as a choice of root canal irrigation in clinical practice. Twenty-five single-rooted teeth were randomly divided into 5 groups： control group （group A） was given 2.5% NaOC1, and 4 experimental groups were given 2.5% NaOC1 and 17% EDTA, including groups B, C, D and E with exposure time of 1, 3, 5 and 7 min, respectively. After preparation of the root canals, the teeth were split along their longitudinal axis, and the root sections were examined under scanning elec- tron microscope for evaluation of smear layer removal and erosion on the surface of the root canal walls. The specimens in group B showed presence of smear layer on the walls of the root canal with no statistical difference from that in group A （P〉0.05）. In groups C and D, partial removal of smear layer was obtained, and there was no significant difference between the two groups （P〉0.05）, but there was significant difference in removal of smear layer between group C and group B （P〈0.05）. Root canal walls in group E specimens showed almost complete removal of smear layer, and the removal of smear layer was significantly different from that in group D （P〈0.01）. There was no significant change in the structure of the surface of root canal for each sample. It was concluded that combined irrigation with 17% EDTA and 2.5% NaOC1 could remove the smear layer with no significant alteration in dentinal structure when the chelating agent was applied for 7 min. At 3 and 5 min of application, partial removal of smear layer was observed and at 1 min negligible removal of smear layer was achieved.     

Morphology of bacterial flora in root canals associated with apical abscesses

Background Apical abscess is an inflammatory process in the peri-radicular tissues caused by biofilms in the necrotic root canal systems. Therefore, a comprehensive analysis of the bacterial colonization is required for a better understanding of the pathogenesis. This study aimed to investigate the patterns of bacterial infection of root canals of teeth with apical abscesses and to determine whether histological and microbiological findings correlated with clinical conditions. Methods Eighteen samples from 18 teeth with apical pathological lesions were analyzed. Nine patients with acute apical abscesses experienced severe pain, and nine patients were asymptomatic with a sinus tract. After extraction, each affected root was divided into two halves. One half was processed for histobacteriologic analysis and examined using light microscopy, and the other half was analyzed using scanning electron microscopy （SEM） to determine the patterns of microbial colonization of the root canals. Results The appearance of each sample subjected to SEM was consistent with the histobacteriologic findings despite the presence or absence of clinical symptoms. Intraradicular biofilms comprising cocci, rods, and/or filaments of amorphous materials were observed in the apical third of the main root canals in all samples. The bacterial biofilms covering the main root canal walls also penetrated the dentinal tubules to varying depths. The morphologies of biofilms varied, and a unique pattern of intraradicular infection was not identified. Conclusion Intraradicular infections formed complex and variable multispecies biofilms and their presence did not correlate with clinical symptoms.     

Three-dimensional finite element analysis of weakened roots restored with different cements in combination with titanium alloy posts

Restoration of endodontically treated teeth with flared root canal and thin walls near the cervica part is frequently a challenge for dentists. It becomes especially complex when the involved teeth have previously undergone treatment for caries, fractures endodontic-access preparation, canal instrument ation, and other idiopathic causes.1,2 These problems result in loss of tooth structure and consequent reduction in tooth resistance to myriad o intraoral forces. 3,4 A number of guidelines have…     

Comparison of bolus remifentanil versus bolus fentanyl for blunting cardiovascular intubation responses in children: a randomized, double-blind study

Background The authors found no study to compare the efficacy of bolus dose fentanyl and remifentanil blunting the cardiovascular intubation response in children, so they designed this randomized, double-blind clinical study to assess the effects of remifentanil 2 μg/kg and fentanyl 2 μg/kg by bolus injection on the cardiovascular intubation response in healthy children.
Methods One hundred and two children, the American Society of Anesthesiologists （ASA） physical status 1-2 and scheduled for elective plastic surgery under general anesthesia, were randomly divided into one of two groups to receive the following treatments in a double blind manner： remifentanil 2μg/kg （Group R） and fentanyl 2 μg/kg （Group F） when anesthesia was induced with propofol and vecuronium. The orotracheal intubation was performed using a direct laryngoscope. Blood pressure （BP） and heart rate （HR） were recorded before anesthesia induction （baseline values）, immediately before intubation, at intubation and every minute for 5 minutes after intubation. The percent changes of systolic blood pressure （SBP） and HR relative to baseline values and the rate pressure product （RPP） at every observing point were calculated. The incidences of SBP and HR percent changes 〉30% of baseline values and RPP 〉22 000 during the observation were recorded.
Results There were no significant differences between groups in the demographic data, baseline values of BP and HR and the intubation time. As compared to baseline values, BP, HR and RPP at intubation and their maximum values during observation increased significantly in Group F, but they all decreased significantly in Group R. BP, HR and RPP at all observed points, and their maximum values during the observation, were significantly different between groups. There were also significant differences between groups in the percent change of SBP and HR relative to baseline values at all observed points and their maximum percent changes during the observation. The incidences of SBP and HR percent increased 〉30% of the baseline values and RPP 〉22 000 during the observation, were significantly higher in Group F than in Group R, but the incidences of SBP and HR percent decreased 〉30% of baseline values were significantly lower in Group F compared with Group R.
Conclusions When used as part of routine anesthesia induction with propofol and vecuronium in children, fentanyl 2 μg/kg by bolus injection fails to effectively depress the cardiovascular intubation response. Remifentanil 2 μg/kg by bolus injection can completely abolish the cardiovascular intubation response, but also cause more adverse complications of temporary siclnificant cardiovascular depression.     

A comparison between radiovisiography and clearing technique in the study of the root canal types

Objective： To compare the radiovisiography （RVG） with the clearing technique using Kappa value in the study of the root canal types. Methods： One hundred recently extracted human maxillary first premolars were used. Standard periapical RVG images were taken from a buccolingual and mesiodistal direction. The specimens were then accessed, injected with ink, demineralized, dehydrated, and finally were cleared. The RVG images and the transparent teeth were examined by a trained endodontist, and the date of root canal types following Wu＇ s classification was collected. Results： The reliability of RVG was high for studies on simple root canals, but was poor for the studies on the multiple root canals. The Kappa value between the two techniques was 0.3793, indicating the agreement was poor. Conclusion： It is concluded that the limited value of RVG alone when studying certain aspect of the mot canal system. The resolution of the RVG system should be enhanced.     

Fracture resistance and pattern of the upper premolars with obturated canals and restored endodontic occlusal access cavities

We studied whether obturing canals and restoring endodontic occlusal access cavities on upper premolars could provide acceptable resistance and pattern to fracture.Eighteen upper premolars were divided equally into 3 groups.Group 1 consisted of intact controls;group 2 had access cavities and root canal preparations;group 3 as in group 2 but obturated with gutta-percha and AH26,and the access cavity restored with glass ionomer and composite.Specimens were submitted to compressive strength testing using the Hounsfield Universal H50KM testing machine with a load cell of 2000 Newtons and a crosshead speed set at 1.0 mm/min until fracture.The results from the compressive strength tests showed that intact controls （1105.83±90.93 MPa） and restored premolars （936.67±44.67 MPa） were significantly different from premolars with unrestored access cavities 568.33±105.49 MPa.There was no significant difference between intact controls and restored premolars.The predominant fracture pattern for intact teeth was an oblique fracture.For premolars that had endodontic access cavities,restored or unrestored,the most common fracture pattern was a vertical fracture.The restoration of occlusal access cavities with glass ionomer and composite provided fracture resistance close to that of intact controls,but when restored teeth fractured,they were predominantly non-restorable.     

Prevalence of dental caries among preschool children in Shanghe County of Shandong Province and relevant prevention and treatment strategies

Background Decayed teeth are harmful to children＇s growth and development and can severely jeopardize their health. This study was set out to investigate and analyze the prevalence of dental caries in preschool children in Shanghe County in Shandong Province, China, and provide new insights into potential prevention and treatment strategies. Methods Based on the random sampling method, we performed dental examinations of children aged 2 to 6 years in kindergartens of Shanghe County. The prevalence of caries, the average number of decayed teeth per capita as well as the constituent rates of decayed, missing and filled teeth were determined retrospectively. SPSS software was used for data analysis. Results Dental caries were found in 1088 out of 2052 children from 56 kindergartens. The total number of decayed teeth was 4487 with a prevalence of 53.02%. The average number of decayed teeth per capita was 2.187, and the filling rate was 0.29%. There was no statistical difference in the prevalence of caries between boys and girls though there were significant differences between different age groups. The prevalence of decayed teeth as well as the mean number of decayed teeth infected per capita increased with age. In addition, urban children had a higher prevalence than those from rural areas （P 〈0.01）. Conclusions The prevalence of decayed caries among kindergarten children in Shanghe County was high, suggesting that more emphasis should be put on improving oral health education with priority given to prevention. Further efforts should be made to increase the decayed caries filling rate.     

Studies on the Optimum Concentration and Performance of Hydrogen Sulfide in Isolated Rat Heart Preservation

Objective To investigate the preservation of isolated rat heart in HST （H2S St. Thomas Ⅱ solutions） solutions with different concentrations of hydrogen sulfide （H2S）. Methods The isolated hearts of 32 SD rats were randomly divided into four groups and preserved in St. Thomas Ⅱ solution （Group Ⅰ）, HST with 0.1μmol/L Naris （Group Ⅱ）, HST with 1 μmof/L Naris （Group Ⅲ） and HST with 10μmol/L Naris （Group Ⅳ）, respectively. The functions of the hearts, i.e. recovery rate of the heart function, energy changes, and water content in the heart muscles and ultrastructure of the heart were then determined by Langendorff heart perfusion and function model after six hours of preservation. Results After six-hour preservation, the functions of the left ventricle in Group Ⅳ were seriously damaged while those in Group Ⅱ and Ⅲ were slightly damaged. The damage to the left ventricle in Group Ⅳ was the slightest. The differences between Group Ⅰ and other groups in contents of ATP, lactic acid （LD） and hepatin were statistically significant. The recontract time in Group Ⅳ was longer than that in Group Ⅰ. As for the ultrastructure of the heart muscle, the damage to the hearts in Group Ⅲ was slightest. Conclusion The preservation and protection of isolated rat heart was better in HST solution than in STH solution within six hours. HST solution with 1 μmol/L NariS can achieve the optimum preservation while H2S with higher concentrations can cause damage to the heart muscle.     

根管超声清理效果的扫描电镜评价

新鲜离体的同体同名牙8对,随机分为2组,1组用超声器械进行根管预备,另1组用手持器械进行根管预备。术后用扫描电镜对根管壁进行观察照像,将清洁度分为3级,盲评的结果经统计处理表明:超声处理组根管壁的清洁度高于对照组。另外,发现用超声器械进行根管预备节省时间。     

3种根管预备方法再处理根管治疗失败病例的比较研究

目的 :比较手用器械根管预备、化学方法辅助手用器械预备、超声波根管预备 3种方法在根管治疗失败后再处理病例中的效果 ,评价其优越性。方法 :将 78个根管治疗失败患牙随机分为 3组 ,分别采用 3种方法去除原充填物 ,预备根管 ,随后均按常规根管消毒、充填 ,完成根管治疗。比较其根管充填物去除率、根管治疗期间的急症 (EIAE)发生率。结果 :根管充填物去除率方面 ,手用器械法和其他 2法有统计学意义 (P <0 0 0 1) ,化学法与超声法之间无统计学意义。在根管预备后EIAE发生率上 ,3种方法间无统计学意义 (P >0 0 5 )。结论 :化学方法和超声方法优于手用器械法 ,化学方法比超声方法价廉 ,易于操作 ,有一定临床应用价值     

不同根管清洗方法清洁效果的扫描电镜观察

目的比较3种不同根管清洗方法的根管清洁效果。方法30颗离体单根管牙应用逐步后退法进行根管扩大,采用3种根管清洗方法进行根管清洁。分为超声清洗组(A组),传统注射器冲洗组(B组)和根管棉捻擦洗组(C组),每组10颗牙。将牙体沿颊舌向纵劈,应用扫描电镜对各组在根冠1/3,中1/3及尖1/3部位玷污层清洗的效果进行观察。统计学分析比较各组根管清洁的差异。结果根冠1/3:3组间差异无统计学意义;根中1/3和尖1/3:A、B组均优于C组(P<0.05),A组优于B组(P<0.05)。结论超声根管清洗对根管玷污层的清洗效果最好,根管棉捻擦洗清洗效果较差。     

纤维桩修复不同箍结构前磨牙的牙根抗力研究

目的研究不同形态的箍结构对纤维桩核修复下颌前磨牙后牙体抗力的影响。方法将48颗下颌第一前磨牙分为6组。第1组:根管治疗后全冠修复;第2组:具有1 mm的360°包绕的箍结构;第3组:仅颊侧有1 mm的箍结构;第4组:仅舌侧有1 mm的箍结构;第5组:颊、舌侧有1mm的箍结构;第6组:无箍结构。所有离体牙均用纤维桩、树脂核及烤瓷熔附金属全冠修复,并以1 mm/min的速率加载压缩力,直到出现断裂。结果第1组牙根折裂的加载力值为(1067.6±234.30)N,大于第六组的(668.9±230.90)N(P<0.05),其余组间比较无统计学意义(P>0.05)。结论纤维桩核冠可用于各种情况的前磨牙残根的修复。     

超声冲洗技术应用于牙髓炎一次性根管治疗的临床疗效观察

目的观察超声冲洗技术在牙髓炎一次性根管治疗术中的应用效果。方法筛选牙髓炎病人397例共412颗患牙,随机分为2组,观察组198例205颗患牙,对照组199例207颗患牙。所有病人均在局麻下行镍钛器械根管预备,观察组以2%次氯酸钠和0.9%氯化钠溶液分别注入超声震荡仪冲洗根管,对照组用5 mL注射器以2%次氯酸钠和0.9%氯化钠溶液冲洗根管。2组病人冲洗完成后均干燥根管热压胶充填,记录治疗后侧支根管充填率和充填1周后的疼痛反应以及1年后的疗效。结果观察组侧支根管充填率明显高于对照组（P < 0.01）;对照组疼痛发生率明显高于观察组（P < 0.01）;2组远期临床疗效差异无统计学意义（P>0.05）。结论超声冲洗技术在牙髓炎病人一次性根管治疗过程中明显提高了侧支根管的充填率,减少了根管治疗术后的疼痛反应,提高了根管治疗术的疗效。     

根管预备的直径不同对超声根管冲洗效果影响的SEM研究

[目的]观察离体牙根管预备冲洗后根管壁残存碎屑量以及牙本质小管口直径,探讨在超声根管冲洗中,根管预备的直径不同对根管冲洗效果的影响.[方法]将60颗离体牙随机分成 A1、A2、A3和B1、B2、B3六组,每组10颗牙,进行预备和冲洗.A组以注射器冲洗,B组以超声波冲洗.根管冲洗液均使用5.25% NaClO溶液.制作扫描电镜标本,评价根管壁牙本质表面残存碎屑量、测量牙本质小管口直径.[结果]①残存碎屑量A1、A2、A3三组在根管的冠1/3、中1/3、和尖1/3均有大量碎屑残存.超声冲洗组,根管壁玷污层被去除,牙本质小管口暴露.A1、A2、A3三组与 B1、B2、B3三组在根管冠1/3、中1/3、尖1/3三部位的残存碎屑量比较,差异有显著性意义(P＜0.05).B1、B2、B3三组在根管冠1/3、中1/3和尖1/3的残存碎屑量,差异无显著性意义(P＞0.05).②B1、B2、B3三组间在冠1/3、中1/3、尖1/3三部位的牙本质小管口直径,差异有显著性意义(P＜0.05);每两组间比较,差异有显著性意义(P＜0.05).[结论]使用相同剂量的NaClO溶液时,在去除根管壁牙本质表面玷污层和根管壁牙本质表面碎屑的效果上,超声根管冲洗优于人工注射器冲洗.在超声根管冲洗中,增大根管预备的直径能提高冲洗液去除玷污层的效果.超声根管冲洗以NaClO为冲洗液时,对牙本质小管口及管周牙本质没有造成过度脱矿和蚀刻.     

Er：YAG激光PIPS技术对乳牙根充糊剂渗透牙本质小管影响的体外研究

目的 使用激光扫描共聚焦显微镜（confocal laser scanning microscope,CLSM）评估掺铒钇铝石榴石铒激光(erbium:yttrium-aluminium-garnet laser,Er：YAG)光子引发的光声流技术（photon-initiated photoacoustic streaming,PIPS）荡洗乳牙根管后根充糊剂渗透牙本质小管的效果。 方法 收集20颗乳切牙和20颗乳磨牙,按不同根管冲洗方法及牙位随机分为4组（n=10）,分别是乳切牙注射器冲洗组（A组）、乳切牙PIPS-Er：YAG激光组（B组）、乳磨牙注射器冲洗组（C组）、乳磨牙PIPS-Er：YAG激光组（D组）。体外行常规根管预备和不同方式的根管冲洗,使用混有罗丹明荧光剂的Vitapex根充糊剂进行根管充填,并用CLSM观察距根尖3 mm（根尖1/3）和5 mm（根中1/3）处的横剖面,测量根充糊剂渗入牙本质小管的长度,比较不同冲洗方法对乳牙根充糊剂渗透深度的影响。 结果 B组、D组根充糊剂在乳牙根管内的渗透深度分别大于A组、C组,A组、B组根充糊剂在乳牙根管内的渗透深度分别大于C组、D组,各组在距根尖5 mm处根充糊剂在乳牙根管内的渗透深度均大于距根尖3 mm处,差异有统计学意义(P＜0.05)。 结论 PIPS-Er：YAG激光荡洗比传统单独使用注射器冲洗效果好,可以明显增加乳牙根充糊剂的渗透深度,但是根管形态会影响冲洗效果。     

根管超声预备效果的扫描电镜观察

目的 探讨根管超声预备的清理效果。方法 正常和病变离体牙根共40个，分5组分别进行手用器械和不同功率超声波的根管预备，电镜观察根管上1/3、中1/3和下1/3不同部位的清理效果。结果 与手用根管预备相比，根管超声预备明显减少了根管壁玷污层和细菌的数量和密度。结论 高档功率超声波能提高根管预备的质量，清理效果以根中1/3为佳；但超声波不能彻底去除根管内的细菌和牙髓组织，尚不能证实超声波本身具有杀菌作用。     

不同根管封闭剂根尖封闭性能的体外研究

目的：比较4种根管封闭剂的体外根尖封闭能力,为临床医师选择应用提供参考。方法：选取78颗单根管离体牙,采用机用ProTaper镍钛器械根管预备后随机分为A、B、C、D 4个实验组（每组18颗牙）和2个对照组（每组3颗牙）。 A组牙胶尖/Cortisomol封闭剂、B组牙胶尖/AH-plus封闭剂、C组牙胶尖/Roek-Seal封闭剂、D组Resilon/RealSeal SE封闭剂。 E组为阳性对照组、F为阴性对照组,各组均使用冷侧压方法进行根管充填。将实验组牙齿（每组10颗）及对照组牙齿进行染色微渗漏实验;实验组牙齿（每组8颗）,扫描电镜下观察封闭剂与根管壁结合情况。结果：A组染料渗入长度（0.94±0.21） mm,高于其余三组[B组（0.65±0.23） mm、C组（0.56±0.15） mm,D组（0.45±0.15） mm）]（P〈0.05）。扫描电镜显示各组根管封闭剂与根管壁形成的最大缝隙宽度比较,差异有统计学意义（P〈0.05）。 A组最大缝隙宽度最大（28.73±7.42）μm,D组次之（4.93±0.89）μm,B组（0.89±0.47）μm、C组（0.86±0.43）μm最小。结论：树脂类根管封闭剂根尖封闭性能明显优于氧化锌类封闭剂,不同树脂类根管封闭剂则各有优势。     

上颌第一磨牙近中颊根第二根管的治疗体会

目的探讨在临床上上颌第一磨牙近中颊根第二根管(MB2)的发现及扩通。方法在25例需要进行根管治疗的上颌第一磨牙上寻找MB2,若无法找到,使用超声根管异物清除工作尖10P清理髓底及慢速圆钻去除预计位置部分牙本质,再次寻找。找到后通畅根管,若无法扩通,使用慢速圆钻在MB2根管口处向根方去除少量牙本质,结合使用EDTA再次通畅根管。结果25颗治疗齿中有13颗找到MB(252%),其中2颗是在超声根管锉清理髓室底后发现的,4颗在进一步去除MB2根管口位置的牙本质后发现。8颗治疗齿的MB2通畅(32%),其中3颗自然扩通,5颗在去除MB2根管口处部分牙本质并使用EDTA后通畅。结论临床上上颌第一磨牙MB2发现率为52%,扩通率为32%。掌握MB2的解剖位置,使用超声方法以及EDTA可提高MB2的发现率和扩通率。