牙体牙髓病根管治疗应用iRoot SP冷侧法的效果

目的探讨牙体牙髓病根管治疗应用iRoot SP冷侧法的效果。方法筛选2018-06至2020-06在解放军总医院京南医疗区就诊的牙体牙髓病患者100例,随机分为对照组和试验组,每组50例,均进行根管治疗,其中对照组充填根管采用热牙胶垂直加压法,试验组采用iRoot SP冷侧法。比较两组根管充填效果、临床总有效率、疼痛视觉模拟评分(VAS)及咀嚼功能。结果两组治疗后根管充填效果和临床总有效率比较,差异无统计学意义(P>0.05);试验组治疗后1周[(4.13±0.79)vs.(5.11±0.98)]及1个月[(2.45±0.37)vs.(3.11±0.67)]VAS评分低于对照组,治疗后咬合力[(131.25±11.21)lbs vs.(120.34±14.09)lbs]及咀嚼效率[(90.12±4.13)%vs.(78.98±7.45)%]均优于对照组,差异均有统计学意义(P<0.05)。结论根管治疗牙体牙髓病中应用iRoot SP冷侧法的充填效果和疗效与热牙胶垂直加压法基本相同,但iRoot SP冷侧法在减轻患者疼痛,改善咀嚼功能方面更具优势。

Root Canal System Variation in Mandibular Second Molar: Middle-Mesial Canal

Middle-mesial canals in mandibular molars are present in the population depending on age, sex and ethnicity. However, limited literature alludes to its prevalence. Troughing procedures may enhance identification, cleaning and shaping. This case report expresses the recognition and management of middle-mesial canal in a mandibular second molar of 24 years old Hispanic-Latino male.

Root Canal Treatment Outcome and Restorative Condition of Teeth Treated by Undergraduates—A Clinical and Radiographic Evaluation

Background: The aim was to evaluate the nonsurgical Root Canal Treatment (nRCT) outcome, the restorative condition and the relationship between the coronal restoration quality and the outcome of teeth endodontic treated by undergraduates at the University of Caxias do Sul School of Dentistry (UCS-SD), Brazil, between 2019 and 2021. Materials and Methods: Data from the endodontically treated cases were retrieved, and the patients were recalled for a follow-up appointment at the university. The endodontic diagnosis, radiographs, and the presence of definitive restorations were analyzed in the clinical records. During the follow-up appointment, endodontically treated teeth were classified as present or absent. The nRCT was classified as successful (complete or incomplete healing) or failure (uncertain or unsatisfactory healing). Coronal restoration was classified as absent or present. When it was present, it was classified as permanent or temporary, and its quality as adequate or inadequate restoration. The results were presented as percentages. Results: A total of 257 teeth were endodontically treated. The most prevalent diagnosis was Chronic Apical Periodontitis (33.33%) and the most commonly treated teeth were premolars (46.15%). A total of 52 (21%) treated teeth were clinically and radiographically reexamined. The success rate for the nRCT was 98.08%. About 61.54% of this sample had a definitive composite resin restoration. Conclusion: The nRCT success rate was high. Special attention should be given to the presence and quality of the definitive restoration. Clinical Implications: There was no statistically significant impact between the coronal restoration and the nRCT success (P > 0.05).

生物陶瓷封闭剂nRoot和生物陶瓷牙胶尖的根尖封闭性研究

目的:体外评价国产新型生物陶瓷根管封闭剂nRoot的根尖封闭性以及应用生物陶瓷根管封闭剂时生物陶瓷牙胶尖的根尖封闭性,为临床材料选择提供理论依据。方法:选取单根管的离体前磨牙,自釉牙骨质界处截去牙冠,随机分为四个实验组和两个对照组。通过逐步深入技术进行根管预备,然后采用Martin TroPe推介的生物陶瓷封闭剂改良热牙胶垂直加压充填技术进行根管充填。A组:nRoot根管封闭剂联合生物陶瓷牙胶尖;B组:nRoot根管封闭剂联合普通牙胶尖;C组:iRoot SP根管封闭剂联合生物陶瓷牙胶尖;D组:iRoot SP根管封闭剂联合普通牙胶尖;E组和F组分别为阳性对照组和阴性对照组。通过染料渗透法和扫描电镜法分别观测各组根尖封闭性情况,染料渗透长度越长,微缝隙越宽,表示根尖封闭性越差。结果:染料渗透实验结果显示,A组(2.455±0.137)mm,B组(2.830±0.148)mm,C组(2.426±0.130)mm,D组(2.774±0.163)mm。经方差分析得出,iRoot SP和nRoot差异无统计学意义(P>0.05);生物陶瓷牙胶尖和普通牙胶尖差异有统计学意义(P<0.05),且生物陶瓷牙胶尖染料渗透平均值低于普通牙胶尖;根管封闭剂与牙胶尖交互效应不显著(P>0.05)。扫描电镜结果显示,各组充填材料与牙体组织结合界面均可见大小不等的微缝隙,其中使用普通牙胶尖的B组和D组中,微缝隙较宽,而使用生物陶瓷牙胶尖的A组和C组中,微缝隙相对较小;B组与D组之间,A组与C组之间,微缝隙宽度均没有明显区别。结论:①国产新型生物陶瓷根管封闭剂nRoot具有与进口生物陶瓷根管封闭剂iRoot SP相似的根尖封闭性;②应用生物陶瓷根管封闭剂时,生物陶瓷牙胶尖的根尖封闭性优于普通牙胶尖;③充填材料中根管封闭剂和牙胶尖对根尖封闭性的影响相互独立,互不干扰。

iRoot SP单尖充填技术用于根管再治疗的临床效果

目的探讨iRoot SP单尖充填技术用于根管再治疗的临床效果。方法选取2021年2月至2022年1月于长沙市口腔医院行根管再治疗的96例患者作为研究对象,根据随机数字表法将其分为研究组(n=48)和参考组(n=48)。研究组行iRoot SP单尖充填,参考组行AH-Plus热牙胶垂直加压法充填。比较两组的根管充填效果、单根管填充时间、疼痛程度、疗效、咀嚼功能。结果两组的根管充填效果比较,差异无统计学意义(P>0.05)。研究组的单根管填充时间为(58.88±5.21)s,短于参考组的(92.35±7.24)s,差异有统计学意义(P<0.05)。研究组术后1、7 d的视觉模拟评分法(VAS)评分为(4.28±0.79)分、(2.97±0.35)分,均低于参考组的(6.54±2.02)分、(3.87±1.21)分,差异有统计学意义(P<0.05);两组的疗效及治疗总有效率比较,差异无统计学意义(P>0.05);术后,两组患者的咀嚼效率、咬合力均高于本组术前,且研究组的咀嚼效率、咬合力均高于参考组,差异有统计学意义(P<0.05)。结论根管再治疗使用iRoot SP单尖充填技术可在确保疗效的同时缩短填充时间,减轻患者疼痛,改善咀嚼功能,值得临床推广使用。

新型生物陶瓷材料iRoot SP在微创根管治疗中的应用效果

目的研究在微创根管治疗中应用新型生物陶瓷材料iRoot SP的临床效果。方法选取100例本院于2022年3月—2023年5月收治的微创根管治疗患者,应用随机法分组,分为观察组和对照组,每组50例。其中观察组采用新型生物陶瓷材料iRoot SP填充,对照组采取AH-PLUS糊剂填充,比较两组治疗有效率、治疗前后牙周健康状态(牙周探诊深度、龈沟出血指数、牙龈指数、牙菌斑指数)、术后疼痛评分、术后观察期间急症反应发生率以及不良反应(瘙痒、红肿、肿痛)发生率。结果治疗6个月后,观察组、对照组治疗有效率比较,观察组更高(P<0.05);术后1、3、5、7 d,观察组疼痛评分相比对照组均更低(均P<0.05);治疗后,观察组牙周探诊深度、龈沟出血指数、牙龈指数、牙菌斑指数等指标水平均低于对照组(均P<0.05);随访6个月,观察组急症反应发生率以及不良反应发生率均低于对照组(均P<0.05)。结论应用新型生物陶瓷材料iRoot SP微创根管治疗,可提高患者治疗效果,使患者疼痛减轻,有利于患者口腔健康。

iRoot SP单尖法根管充填联合牙周基础治疗糖尿病患者慢性根尖周炎疗效观察

目的:探究iRoot SP单尖法根管充填治疗糖尿病合并慢性根尖周炎患者的疗效及美学效果。方法:选取2020年8月-2022年12月笔者医院收治的120例糖尿病合并慢性根尖周炎患者,采用数字化随机法将其分为观察组和对照组,每组60例。对照组采用AHPlus+热牙胶垂直加压技术充填治疗,观察组采用iRoot SP单尖法根管充填治疗。观察比较两组患者根管充填时间、充填后1 d、3 d、5 d和7 d的疼痛VAS评分,充填前后根尖周指数(Periapical index,PAI)、充填后3个月的临床疗效,充填前后患者红色美学指数评分(Pink esthetic score,PES)和白色美学指数评分(White esthetic score,WES),充填前后患者的菌斑指数(Plaque index,PLI)、牙周袋探诊深度(Probing depth,PD)和龈沟出血指数(Sulcus bleeding index,SBI)。结果:对照组充填单位根管时间较观察组长,充填后1周内观察组患者PAI指数低于对照组,且充填后1 d、3 d、5 d、7 d的VAS评分低于对照组(P<0.05);充填后3个月,观察组的总有效率与对照组相当,差异无统计学意义(P>0.05);充填前,两组患者PES和WES评分比较,差异无统计学意义(P>0.05),充填后3个月,观察组患者PES和WES评分均高于对照组,PLI、PD及SBI均低于对照组(P<0.05)。结论:相较AHPlus+热牙胶垂直加压技术,iRoot SP单尖法充填治疗糖尿病慢性根尖周炎患者的充填效率更高,充填后疼痛感更轻,成功率更高,美学效果更显著,值得临床推广应用。

微创根管治疗中使用iRoot SP与AH PLUS材料对牙髓炎患者填充效果、炎症和疼痛的影响比较

目的:比较微创根管治疗中使用爱汝特SP生物陶瓷根管封闭糊剂(iRoot SP)与登士柏AH Plus根管充填材料(AH PLUS)对牙髓炎患者填充效果、炎症、疼痛的影响.方法:选择本院2023年1月至2023年6月收治的牙髓炎患者80例,随机分成对照组和观察组(n=40),微创根管治疗中对照组用AH PLUS,观察组用iRoot SP.治疗1 w后对比填充效果;治疗前、治疗1 w后采用酶联免疫吸附法测定龈沟液炎症因子肿瘤坏死因子-α(Tumor necrosis factor-α,TNF-α)、C-反应蛋白(C-reactive protein,CRP)、细胞白介素-6(Interleukin-6,IL-6)水平;治疗前、治疗后12 h、24 h、72 h采用视觉模拟评分(Visual Analogu Scale,VAS)评估患者疼痛程度;治疗前、治疗1 w后采用牙周探针测定牙周袋深度(Periodontal pocket depth,PD)、牙龈指数(Gingival index,GI)、菌斑指数(Plaque index,PIL);观察记录治疗期间的不良反应.结果:观察组总适填率高于对照组(P<0.05);观察组治疗1 w后TNF-α、CRP、IL-6、治疗后12 h、24 h VAS评分以及治疗1 w后PD、GI、PIL均低于对照组(P<0.05);两组不良反应差异无统计学意义(P>0.05).结论:牙髓炎患者微创根管治疗中使用iRoot SP填充效果更好,改善炎症、疼痛、牙周指标更有效.

IRoot Sp糊剂联合牙胶尖一次性根管充填治疗慢性牙髓炎患者的效果

目的:观察IRoot Sp糊剂联合牙胶尖一次性根管充填治疗慢性牙髓炎患者的效果。方法:选取2022年9月至2023年9月该院收治的76例慢性牙髓炎患者进行前瞻性研究,按随机数字表法将其分为对照组38例(41颗)与观察组38例(42颗)。对照组采用氧化锌丁香油糊剂联合牙胶尖一次性根管充填治疗,观察组采用IRoot Sp糊剂联合牙胶尖一次性根管充填治疗,比较两组充填效果,治疗前后疼痛程度[视觉模拟评分法(VAS)]评分、牙周相关指标[牙周袋深度(PD)、出血指数(BI)、牙龈指数(GI)、菌斑指数(PLI)]水平和龈沟液炎性因子[肿瘤坏死因子-α(TNF-α)、白细胞介素-6(IL-6)、白细胞介素-10(IL-10)、前列腺素E2(PEG2)]水平。结果:观察组充填优良率为94.74%(36/38),高于对照组的73.68%(28/38),差异有统计学意义(P<0.05);治疗后3、7 d,两组VAS评分均低于治疗前,且观察组低于对照组,差异有统计学意义(P<0.05);两组PD、PLI、BI、GI均低于治疗前,且观察组低于对照组,差异有统计学意义(P<0.05);两组TNF-α、IL-10、PEG2、IL-6水平均低于治疗前,且观察组低于对照组,差异有统计学意义(P<0.05)。结论:IRoot Sp糊剂联合牙胶尖一次性根管充填治疗慢性牙髓炎患者可提高充填优良率,降低疼痛程度评分、龈沟液炎性因子水平和牙周相关指标水平,其效果优于氧化锌丁香油糊剂联合牙胶尖一次性根管充填治疗。

iRoot SP配合单尖法根管充填治疗牙体牙髓病的效果及对牙周状态和龈沟液炎性因子水平的影响

目的 探讨iRoot SP配合单尖法根管充填治疗牙体牙髓病的效果及对牙周状态和龈沟液炎性因子水平的影响。方法 选取2020年1月—2022年1月收治的牙体牙髓病82例,按治疗方法分为观察组和对照组各41例,观察组应用iRoot SP配合单尖法治疗,对照组应用iRoot SP配合冷测压法治疗。比较2组临床疗效、充填情况、牙周状态、龈沟液炎性因子水平及疼痛情况。结果 治疗后,观察组临床总有效率和恰填率高于对照组(P<0.05)。观察组治疗后牙周探诊深度、探诊出血指数、牙齿松动度、菌斑指数、临床附着水平及超敏C反应蛋白、肿瘤坏死因子-α、白细胞介素-1β均低于对照组(P<0.05,P<0.01)。治疗后,观察组疼痛总发生率低于对照组(P<0.05)。结论 iRoot SP配合单尖法根管充填能够提高牙体牙髓病的临床疗效,改善患者充填情况以及牙周状态,降低龈沟液炎性因子水平及减轻患者疼痛。

Tooth anatomy risk factors influencing root canal working length accessibility

The aim of this study was to analyze the specific influence of root canal anatomy on the accessibility of working length during root canal therapy. Four hundred seventy-six root canal therapy cases （amounting to a total of 1 005 root canals） were examined. The anatomy risk factors assessed in each case included： tooth type （tooth location）, root canal curvature, and root canal calcification, as well as endodontic retreatment. The investigation examined the correlation between each of these anatomic factors and the working length, with statistical analysis consisting of Chi-square tests and multiple logistic regression analysis. In an independent factor analysis, tooth type （tooth iocation）, root canal curvature, canal calcification, and endodontic retreatment were determined to be the primary risk factors. In a multiple-factor regression model, root curvature and canal calcification were found to most significantly influence root canal working length accessibility （P〈0.05）. Root canal anatomy increases the difficulty of root canal preparation. Appropriate consideration of tooth anatomy will assist in accurate determination of preparation difficulty before instrumentation. This study alerts clinical therapists to anatomical factors influencing the working length accessibility, and allows for a direct estimate of success rate given in situ measurements of tooth factors during the root canal treatment procedure.

An in vitro study on the efficacy of removing calcium hydroxide from curved root canal systems in root canal therapy

To compare the efficacy of various irrigants(citric acid, ethylenediaminetetraacetic acid(EDTA) and Na OCl) and techniques in removing Ca(OH)2in two types of curved root canal systems, simulated root canals with specific curvatures were used to investigate the effects of different irrigants and instruments on Ca(OH)2removal. The optimal methods were verified on extracted human teeth. Simulated root canals were assigned to one of two groups based on the irrigation solution: 10% citric acid or2.5% Na OCl. Each group was divided into four subgroups according to the technique used to remove Ca(OH)2. The percentage of Ca(OH)2removal in different sections of root canals was calculated. On the basis of the results obtained for the simulated canals, 10% citric acid and 17% EDTA were applied to remove Ca(OH)2from the extracted human teeth with curved root canal systems. The teeth were scanned by micro computed tomography to calculate the percentage of Ca(OH)2removal in the canals.In simulated root canals, we found that 10% citric acid removed more Ca(OH)2than 2.5% NaOCl in the 0–1 mm group from the apex level(Po0.05). Ultrasonic and Endo Activator activation significantly removed more Ca(OH)2than a size 30 K file in the apical third(Po0.05). However, there were no significant differences in any sections of the canals for 10% citric acid or 17%EDTA in removing Ca(OH)2in extracted human teeth. We concluded that it was effective to remove residual Ca(OH)2using the decalcifying solution with Endo Activator or Passive Ultrasonic Irrigation in a curved root canal system. A protocol for Ca(OH)2removal was provided based on the conclusions of this study and the methods recommended in previous studies.

Incidence of C-shaped root canal systems in mandibular second molars in the native Chinese population by analysis of clinical methods

The aims of the study were to investigate the incidence of C-shaped root canal systems in mandibular second molars in a native Chinese population using radiography and clinical examination under microscope and to compare the relative efficacies of these methods. For the recognition of C-shaped root canal system, 1 146 mandibular second molars were selected and examined. Teeth with C-shaped canal systems were categorized by using the radiographic classification criteria and the modified Melton＇s method. C-shaped canals were identified in 397 （34.64%） mandibular second molars by radiography （type I, 31.23%; type II, 38.29%; type III, 30.48%）. Clinical examination showed that 449 （39.18%） cases exhibited C-shaped canal systems （C1, 22.94%; C2, 48.11%; C3a, 15.59%; C3b, 13.36%）. As for the result of the radiographic and clinical combined examination, C-shaped root canals were found in 473 （41.27%） mandibular second molars （C1, 21.78%; C2, 45.67%; C3a, 16.70%; C3b, 15.86%）. The incidence of C-shaped root canal diagnosed by radiographic method was statistically different from that by clinical examination and the combined examination （P〈O.05）. The study indicated a high incidence of C-shaped canal system in a Chinese population. The combination of microscopic and radiographic examination is an effective method in identifying the C-shaped root canal system.

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.

Effect of restoration technique on resistance to fracture of endodontically treated anterior teeth with flared root canals

This study was designed to compare the impact of post and core systems on resistance to fracture of endodontically treated anterior teeth with flared root canals and to assess their fracture pattern. Sixty central incisors were cut horizontally 2 mm coronal to the cementoenamel junction(CEJ). After root canal therapy, teeth were assigned into 6 groups(n = 10 each) based on a post system and used as follows: Group C, non-flared root received size #1 glass fiber posts(Control); Group AP, flared root restored with anatomical post; Group RC, flared root restored with size #1 fiber post and cemented with thick layer of resin cement; Group CR, flared root restored with size #1 and reinforced with composite resin; Group CM, cast post-core; Group CP, CAD/CAM polymer-infiltrated ceramic post and core.Following post cementation, core build-up and crown insertion, the specimens were thermo-cycled up to 10,000 cycles(5 C/55 C; 30 seconds dwell time, 6 seconds transition time) and then statically loaded at 1 mm/minute crosshead speed using a universal testing machine. One-way ANOVA and Tukey HSD post hoc test(α= 0.05) were used for data analysis. Group C recorded significantly higher resistance to fracture values [(826.9±39.1) N] followed by group CP [(793.8±55.6) N] while group RC yielded the lowest fracture resistance values [(586.7±51.4) N]. The resistance to fracture of wide root canals can be enhanced by using one-piece CAM/CAM post and core as an alternative to the use of either glass fiber post, relined with composite resin increasing the thickness of luting cement or the use of cast post and core system. However, this was an in vitro investigation and further in vivo studies are necessary.

Root canal morphology and configuration of 123 maxillary second molars by means of micro-CT

The aim of this study was to investigate the root canal configuration, accessory canals and number of main foramina of 123 maxillary second molars by means of micro-computed tomography. The teeth were scanned and reproduced with 3D software imaging. The root canal configuration and number of main foramina were evaluated by means of a four-digit system. The morphological complexity of human maxillary second molars is depicted by the number of accessory and connecting canals. The most frequently observed root canal configurations in the mesiobuccal root were 2-2-2/2 （19.5%）, 2-2-1/1 （14.6%） and 2-1-1/1 （13.0%）. A 1-1-1/1 configuration was observed in 93.5% and in 96.7% in the distobuccal and palatal roots, respectively. The MB1 mot canal had one accessory canal （18.7%）, and 8.9% of the MB2 root canal had one or two accessory canals. The distobuccal （11.3%） and palatal （14.6%） root canals had at least one accessory canal, and connecting canals were observed in 16.3% of mesiobuccal roots. The MB1, MB2, distobuccal and palatal root canals had one main foramen in 99.2%, 43.1%, 98.4% and 99.2% of samples, respectively. In the mesiobuccal root, one accessory foramen was detected in 14.6%, two were detected in 7.3%, and three were detected in 5.7%. The distobuccal root showed one or two accessory foramina in 9.1% of samples. The root canal configuration of maxillary second molars is quite heterogeneous; the mesiobuccal root has predominantly two root canal entrances （58.4%, 1 in 41.1%） with one main foramen （54.4%）. Two main foramina were observed in 43.0%. Morphological variations, connecting and accessory canals were observed in all apical thirds.

iRoot SP根充糊剂在外伤性露髓前牙一次性根管治疗中的应用效果

目的探究在外伤性露髓前牙一次性根管治疗中应用iRoot SP根充糊剂的治疗效果。方法100例外伤性露髓前牙患者,随机分为对照组与观察组,各50例。两组患者均应用一次性根管治疗,观察组应用i Root SP根充糊剂,对照组应用AH Plus根充糊剂。对比两组术后24 h、45 h、1周的疼痛程度。结果术后24 h、45 h、1周,观察组视觉模拟评分法(VAS)评分分别为(1.13±0.01)、(0.79±0.07)、(0.69±0.17)分,均明显低于对照组的(1.21±0.10)、(1.27±0.03)、(1.09±0.12)分,差异有统计学意义(P<0.05)。结论iRoot SP根充糊剂在外伤性露髓前牙患者一次性根管治疗中应用,能有效缓解术后疼痛感,提高临床疗效,值得推广。

Endodontic management of the maxillary first molars with two root canals: A case report and review of the literature

BACKGROUND The complex anatomy of the maxillary first molars has always been a major challenge for complete root canal treatment in endodontic therapy. Here, we present two cases of maxillary first molars, each with only two root canals, which have been rarely reported. We also perform a literature review of maxillary first molar anatomy.CASE SUMMARY The two patients were referred to the hospital after 1) finding a cavity in their tooth with a color change and, 2) a toothache during mastication, respectively.Both of these cases were diagnosed as apical periodontitis by X-ray imaging and cone beam computed tomography(CBCT). Non-surgical endodontic therapy was performed with the assistance of a dental operating microscope(DOM). CBCT showed rare but accurate images of both patients, each with two root canals and two roots in their maxillary first molars. Both roots were located in the buccal in the palatal direction, and each root had only one clear root canal. In addition,each maxillary first molar in both patients was symmetrical to that on the opposing side with only two separate root canals. Non-surgical endodontic therapy was performed with the assistance of a DOM. Finally, the teeth were restored using composite resin and the patients were satisfied with the results.CONCLUSION Making full use of CBCT and DOM would contribute to helping dentists make correct diagnoses and successfully treat teeth with rare root canal morphologies.

Calcium Hydroxide Removal in Curved Root Canals with Apical Transportation In Vitro

Calcium hydroxide（CH） is applied to improve disinfection of root canals in most root canal retreatment. This study aimed to analyze the CH removal efficacy using 7 different root preparing files（K file, pre-curved K file, EndoActivator, Ultrasonic file, pre-curved ultrasonic file, F file and needle irrigation alone） with apical transportation. Standardized models of curved canal with such apical transportation or not were set up before applying CH to root canal for 7 days. Seven techniques described above were used for its removal. Then the roots were disassembled and digital photos were taken. The ratio of residual CH in the overall canal surface was calculated using the image analyzer image pro plus 6.0. The data were analyzed using one-way ANOVA with post hoc Tukey test. Results revealed that CH was effectively removed（P〈0.05） by using all 6 mechanical methods except irrigation alone. In curved root canals with apical transportation, EndoActivator, pre-curved ultrasonic file and F file were found to be more effective in removing CH than the other four file（P〈0.001）, while there was no significant difference among EndoActivator, pre-curved ultrasonic file and F file groups（P〉0.05）. The percentage of residual CH in the canal with apical transportation was higher than that in the canal without apical transportation（P〈0.05）. In conclusion, CH can be hardly removed completely. Canal with apical transportation will result in insufficient CH removal. EndoActivator, pre-curved ultrasonic file and F file are more effective in the curved root canal with apical transportation.

Three-dimensional inlay-guided endodontics applied in variant root canals: A case report and review of literature

BACKGROUND Root canal retreatment is common after root canal therapy in clinical situations.Especially,completing the retreatment of variant root canals can be challenging.This is particularly true for the molars located at the end of the dental arch.However,advancements in digital dental diagnosis and treatment techniques can solve these problems.Here,we describe a case of a maxillary second molar with a variant distobuccal root canal treated via a novel“inlay-guided endodontics”technique based on improved computer-generated programs.CASE SUMMARY A 63-year-old man complained of a defect in the maxillary left second molar.The tooth,diagnosed with post-treatment endodontic disease,was initially treated by conventional methods,which were ineffective.Our“inlay-guided endodontics”technique was subsequently adopted,with the establishment of a precise integrated three-dimensional(3D)plate model of cone-beam computed tomography data and a digital impression of the dentition.An optimal root canal approach was generated for the“virtual file”in the 3D model.The plate data were imported into a 3D printer and printed.With the help of the guide plate,the file was accurately placed into the cervical third of the distal root canal.The root canal and prosthodontic treatments successfully proceeded subsequently.CONCLUSION Our newly developed inlay guide plates may facilitate individualized and minimally invasive root canal treatment.