机用镍钛器械Mtwo及K3预备磨牙弯曲根管成形能力的比较

背景：重度弯曲根管的预备是临床根管预备的难点,如预备不当容易出现台阶、根管偏移、根尖孔敞开等并发症,影响根充质量和根尖封闭性,因此选择切削能力和成形能力俱佳的根管预备器械对与弯曲根管预备效果的保证有着重要意义。 目的：比较Mtwo、K3机用镍钛器械与不锈钢手动K-file预备磨牙重度弯曲根管的成形效果。 方法：将30颗新鲜拔除的人离体上颌第一磨牙重度弯曲近颊根管随机均分为3组,分别采用Mtwo机用镍钛器械、K3机用镍钛器械与不锈钢手动K-file进行根管预备。记录3组根管预备前后根管影像中器械尖端所在位置,测量并比较3组间根管弯曲度的变化、工作长度变化和操作时间。 结果与结论：根管预备前,3组根管弯曲度比较差异无显著性意义(P > 0.05);根管预备后,Mtwo机用镍钛器械组、K3机用镍钛器械组根管弯曲度变化小于不锈钢手动K-file组(P < 0.01),Mtwo机用镍钛器械组、K3机用镍钛器械组根管弯曲度变化比较差异无显著性意义(P > 0.05)。3组根管预备时间比较差异有显著性意义(P < 0.01),Mtwo机用镍钛器械组最短,不锈钢手动K-file组最长。3组根管预备后根管工作长度改变比较差异无显著性意义(P > 0.05)。表明Mtwo与K3机用镍钛器械预备后牙弯曲根管时效率高、成形能力强。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

不同根管预备器械对弯曲根管预备效果的影响

目的:研究不同根管预备器械对弯曲根管预备效果的影响。方法:96例牙髓炎或根尖牙周炎患者作为研究对象,共148颗患牙,按照抽签法,分为观察A组、观察B组和对照组,各32例。观察A组Protaper机,观察B组Mtwo机,对照组不锈钢K锉,比较根管预备时间、弯曲度、疼痛反应、根管锥度、流畅度及充填效果。结果:观察A组、观察B组预备时间显著少于对照组（P<0.05）。观察A组、B组比较无显著差异（P>0.05）。预备后3组根管弯曲度均显著降低（P<0.05）。3组组间比较无显著差异（P>0.05）。观察A组、B组疼痛反应显著优于对照组（P<0.05）;观察A组、观察B组前磨牙、后磨牙的锥度和流畅度显著优于对照组（P<0.05）。观察A组（90.63%）、B组（88.89%）适充充填显著优于对照组（80.00%）（P<0.05）。结论:镍钛预备器械的弯曲根管预备快速,能够保持根管形态,提高充填效果。     

应用锥形束CT对华南地区924颗下颌第1磨牙的根管形态学研究

目的　应用锥形束 CT(cone beam computed tomography,CBCT)观察下颌第1磨牙的根管解剖形态,为临床根管治疗提供参考依据。 方法　由两名牙体牙髓专业医生筛选我院口腔科自2014年12月至2015年12月进行 CBCT 检查的500名患者,共计924颗下颌第1磨牙的影像资料,分别记录患者的基本信息、牙位、根管构型及钙化情况,并进行统计学分析。 结果　424名存在双侧下颌第1磨牙的患者中,76.2%(323)根管构型完全对称。924颗下颌第1磨牙中,双根率为76.7%(709),3根率即远舌根发生率为23.3%(215);近中根最常见根管类型为Vertucci IV型,占 71.97%(665),其次为II型,占23.70%(219);远中根最常见根管类型为I型,占 49.35%(458),其次为IV型占31.82%(292)。存在远舌根时,远舌根管口与远颊根管口距离为(2.94±0.27) mm。下颌第1磨牙根管钙化率与年龄有关,老年人钙化率高,中年人次之。 结论　华南地区人群下颌第1磨牙根管形态多样,变异性较大;CBCT 是观察根管形态的有效工具,可以为根管治疗提供辅助诊断。     

Root canal system of the maxillary canine

To better assess the efficacy of mechanical preparation of root canals, transparent specimens of 250 extracted maxillary canines were investigated for canal configuration, thickness and curvature of the root canal, condition of any accessory canals, and location of the apical foramen. Fewer than 40% of the specimens showed accessory canals that were mechanically impossible to clean. The majority of the lateral branches were small, greater than a #15 file, and none of the branches were larger than a #20 file. Although apical foramina located away from the apex were observed in 30% of the maxillary teeth, 96% of all apical foramina were within 0.5 mm of the apex. Data on the thickness of the root and main canal in the apical portion and curvature of the root canal suggest that, for adequate apical preparation, a #60 file must be able to reach the apical constriction.     

Ultrasonographic median nerve cross-section areas measured by 8-point "inching test" for idiopathic carpal tunnel syndrome: a correlation of nerve conduction study severity and duration of clinical symptoms

Background

Together with diagnosis and treatment planning, a good knowledge of the root canal system and its frequent variations is a necessity for successful root canal therapy. The selection of instrumentation techniques for variants in internal anatomy of teeth has significant effects on the shaping ability and cleaning effectiveness. The aim of this study was to reveal the differences made by including variations in the internal anatomy of premolars into the study protocol for investigation of a single instrumentation technique (hand ProTaper instruments) assessed by microcomputed tomography and three-dimensional reconstruction.

Methods

Five single-root premolars, whose root canal systems were classified into one of five types, were scanned with micro-CT before and after preparation with a hand ProTaper instrument. Instrumentation characteristics were measured quantitatively in 3-D using a customized application framework based on MeVisLab. Numeric values were obtained for canal surface area, volume, volume changes, percentage of untouched surface, dentin wall thickness, and the thickness of dentin removed. Preparation errors were also evaluated using a color-coded reconstruction.

Results

Canal volumes and surface areas were increased after instrumentation. Prepared canals of all five types were straightened, with transportation toward the inner aspects of S-shaped or multiple curves. However, a ledge was formed at the apical third curve of the type II canal system and a wide range in the percentage of unchanged canal surfaces (27.4-83.0%) was recorded. The dentin walls were more than 0.3 mm thick except in a 1 mm zone from the apical surface and the hazardous area of the type II canal system after preparation with an F3 instrument.

Conclusions

The 3-D color-coded images showed different morphological changes in the five types of root canal systems shaped with the same hand instrumentation technique. Premolars are among the most complex teeth for root canal treatment and instrumentation techniques for the root canal systems of premolars should be selected individually depending on the 3-D canal configuration of each tooth. Further study is needed to demonstrate the differences made by including variations in the internal anatomy of teeth into the study protocol of clinical RCT for identifying the best preparation technique.     

Assessment of bone channels other than the nasopalatine canal in the anterior maxilla using limited cone beam computed tomography

Purpose

The anterior maxilla, sometimes also called premaxilla, is an area frequently requiring surgical interventions. The objective of this observational study was to identify and assess accessory bone channels other than the nasopalatine canal in the anterior maxilla using limited cone beam computed tomography (CBCT).

Methods

A total of 176 cases fulfilled the inclusion criteria comprising region of interest, quality of CBCT image, and absence of pathologic lesions or retained teeth. Any bone canal with a minimum diameter of 1.00 mm other than the nasopalatine canal was analyzed regarding size, location, and course, as well as patient gender and age.

Results

A total of 67 accessory canals ≥1.00 mm were found in 49 patients (27.8 %). A higher frequency of accessory canals was observed in males (33.0 %) than in females (22.7 %) (p = 0.130). Accessory canals occurred more frequently in older rather than younger patients (p = 0.115). The mean diameter of accessory canals was 1.31 ± 0.26 mm (range 1.01–2.13 mm). Gender and age did not significantly influence the diameter. Accessory canals were found palatal to all anterior teeth, but most frequently palatal to the central incisors. In 56.7 %, the accessory canals curved superolaterally and communicated with the ipsilateral alveolar extension of the canalis sinuosus.

Conclusions

The study confirms the presence of bone channels within the anterior maxilla other than the nasopalatine canal. More than half of these accessory bone canals communicated with the canalis sinuosus. From a clinical perspective, studies are needed to determine the content of these accessory canals.     

Root Canal Morphology of Chalcolithic and Early Bronze Age Human Populations of El Mirador Cave (Sierra de Atapuerca,Spain)

This study provides a morphological characterization of the inner anatomy of the root canals of permanent first and second molars in Chalcolithic and early Bronze Age human fossils using cone‐beam computed tomography. The general evolutionary trend in present‐day human dentition is related to morphological simplification. As little is known about when this trend appeared in Homo sapiens populations, the aim of this work is to test the presence of modern radicular morphology 4,400 years ago. Fifty‐four permanent first and second maxillary and mandibular molars of 17 individuals were included in the study. All maxillary first and second molars showed three separate roots. Almost all the lower molars analyzed (100% of first molars and 75% of second molars) had two separate roots. More differences in the canal system configuration were documented in the maxillary mesiobuccal roots than in the palatal or distobuccal roots. The most variable tooth in root and canal configuration is the maxillary second molar. It should be pointed out that 12.5% of the teeth analyzed showed a C‐shaped root configuration. Anat Rec, 297:2342–2348, 2014. © 2014 Wiley Periodicals, Inc.     

上下颌前牙根根管系统解剖及临床意义

目的了解上下颌前牙牙根数目,根管类型,为临床前牙根管充填提供理论依据。方法采用离体牙经透明牙标本制备,用XXT-3A连续变倍体视显微镜检测上下颌前牙根管系统。结果1973颗前牙1975支牙根的主根管类型分为六型,I型上颌前牙占100%、下颌前牙占74.97%;侧副根管分四种:根管侧支检出率17.97%,管间吻合检出率0.81%,根尖分歧检出率4.61%,根尖分叉7.39%。结论上下颌前牙根管形态及根管系统具有规律性和多变性。     

Analysis of intraindividual and intraspecific variation in semicircular canal dimensions using high-resolution x-ray computed tomography

The semicircular canal system tracks head rotation and provides sensory input for the reflexive stabilization of gaze and posture. The purpose of this study was to investigate the intraspecific and intraindividual variation in the size of the three semicircular canals. The right and left temporal bones were extracted from 31 individuals of the short-tailed shrew ( Blarina brevicauda ) and scanned on a high-resolution x-ray computed tomography system. The radius of curvature was calculated for each of the three semicircular canals for each side. Paired t -tests and independent sample t -tests indicated no significant differences in canal size between the right and left canals of the same individuals or between those of males and females of the same species. Pearson product moment correlation analyses demonstrated that there was no significant correlation between canal size and body mass in this sample.     

Cone beam CT findings of retromolar canals in a Korean population

Purpose

The identification of the variation involving the mandibular canal is important during surgical procedures in the mandible. This study aims to investigate the incidence, course, width, and location of retromolar canals in a Korean population using cone beam CT.

Methods

The cross-sectional, sagittal, and three dimensional images from volumetric cone beam CT data of 446 patients were reconstructed using imaging analysis software for the presence of a retromolar canal. Retromolar canals were classified into three types according to the courses. The width and location (distance from the second molar) of retromolar canals were evaluated.

Results

A retromolar canal was observed in 8.5 % of patients (38/446). Most retromolar canals had vertically curved courses (Type 1, 66.7 %), followed by horizontally curved courses (Type 2, 20 %). Type 3 retromolar canals, which run independently from separate foramina in the mandibular ramus, were rare (13.3 %). The mean width of a retromolar canal was 1.13 mm (SD ± 0.38, 0.60–2.00), and the mean distance to the second molar was 14.08 mm (SD ± 3.85, 8.50–24.00).

Conclusions

The incidence of retromolar canals in the Korean population was lower than that reported in the investigated ethnic groups. In the presence of a retromolar canal, local anesthesia may be ineffective. The damage to a retromolar canal may be unavoidable during surgical procedures involving the mandible and may result in paresthesia, excessive bleeding, postoperative hematoma, or traumatic neuroma.     

Discontinuities in the endothelium of epiphyseal cartilage canals and relevance to joint disease in foals

Cartilage canals have been shown to contain discontinuous blood vessels that enable circulating bacteria to bind to cartilage matrix, leading to vascular occlusion and associated pathological changes in pigs and chickens. It is also inconsistently reported that cartilage canals are surrounded by a cellular or acellular wall that may influence whether bacterial binding can occur. It is not known whether equine cartilage canals contain discontinuous endothelium or are surrounded by a wall. This study aimed to examine whether there were discontinuities in the endothelium of cartilage canal vessels, and whether canals had a cellular or acellular wall, in the epiphyseal growth cartilage of foals. Epiphyseal growth cartilage from the proximal third of the medial trochlear ridge of the distal femur from six healthy foals that were 1, 24, 35, 47, 118 and 122 days old and of different breeds and sexes was examined by light microscopy (LM), transmission electron microscopy (TEM) and immunohistochemistry. The majority of patent cartilage canals contained blood vessels that were lined by a thin layer of continuous endothelium. Fenestrations were found in two locations in one venule in a patent cartilage canal located deep in the growth cartilage and close to the ossification front in the 118‐day‐old foal. Chondrifying cartilage canals in all TEM‐examined foals contained degenerated endothelial cells that were detached from the basement membrane, resulting in gap formation. Thirty‐three percent of all canals were surrounded by a hypercellular rim that was interpreted as contribution of chondrocytes to growth cartilage. On LM, 69% of all cartilage canals were surrounded by a ring of matrix that stained intensely eosinophilic and consisted of collagen fibres on TEM that were confirmed to be collagen type I by immunohistochemistry. In summary, two types of discontinuity were observed in the endothelium of equine epiphyseal cartilage canal vessels: fenestrations were observed in a patent cartilage canal in the 118‐day‐old foal; and gaps were observed in chondrifying cartilage canals in all TEM‐examined foals. Canals were not surrounded by any cellular wall, but a large proportion was surrounded by an acellular wall consisting of collagen type I. Bacterial binding can therefore probably occur in horses by mechanisms that are similar to those previously demonstrated in pigs and chickens.     

The morphology of maxillary first and second molars analyzed by cone-beam computed tomography in a polish population

Background

The success of endodontic treatment is greatly affected by the location of the root canals. The purpose of this study was to evaluate the root and canal morphology of permanent maxillary first and second molars in a Polish population using cone-beam computed tomography scanning.

Methods

Cone-beam computed tomography (CBCT) scans of maxillary first and second molars the maxilla were examined. The number of roots and root canals, and the frequency of additional canals (MB2) in the mesiobuccal root canals were determined. The results were subjected to statistical analysis using the chi-square test or the chi-square test with Yates’ correction.

Results

A total of 112 CBCT images of maxillary first (n?=?185) and second molars (n?=?207) from 112 patients were analyzed. All the maxillary first molars had three roots (100%). The majority of maxillary second molars had three roots (91.8%), 5.8% had two roots and 2.4% had one root. A statistically significant difference was observed between the numbers of roots in the maxillary first and second molars (p?<?0.01). A statistically significant difference was also found in the distribution of the number of canals in the maxillary first and second molars (p?<?0.001). The majority of maxillary first molars had four root canals (59.5%), while 40.5% had three root canals. Most maxillary second molars had three root canals (70%). Additional canals (MB2) in the mesiobuccal roots were detected significantly more frequently in the maxillary first molars than the second molars (p?=?0.000) and more frequently in men than in women (p?<?0.05). A higher prevalence of two canals in the mesiobuccal roots in maxillary second molars occurred in patients aged between 31 and 40 years than in patients aged between 21 and 30 years. In the maxillary first molars, the prevalence of the MB2 canal in the mesiobuccal root was almost equally distributed in the two age groups (21–30 and 31–40 years).

Conclusion

Within the limitations of this study, it can be concluded that there are differences in the number and configuration of roots and root canals between maxillary first and second molars in the studied patients of a Polish population.

     

三种器械对根管清洁效果的比较研究

目的通过比较观察扫描电镜结果,评价不锈钢K锉、机动和手动ProTaper镍钛器械对根管预备的清洁效果。方法选用因正畸治疗而拔除的下颌前磨牙60颗,随机分为3组,每组20颗牙。组A采用不锈钢K锉进行根管预备,组B采用机动ProTaper进行根管预备。组C采用手动ProTaper进行根管预备。根管预备完成后纵剖根管,扫描电镜下观察根管内壁表面的碎屑、玷污层及牙本质小管的形态变化。结果在根管的冠1／3和中1／3段,组B和组C根管壁碎屑含量及玷污层均明显低于组A（P〈0．05）,但组B与组C之间根管壁碎屑含量及玷污层差异无统计学意义（P〉0．05）;在根尖部1／3段,3组之间的根管壁碎屑含量及玷污层差异均无统计学意义（P〉0．05）。结论机动和手动ProTaper镍钛器械对根管的冠1／3和中1／3段的清洁效果显著高于不锈钢K锉,但3种器械对根尖1／3段的根管壁碎屑及玷污层的清洁效果无显著性差异。     

Mandibular lingual canals distribute to the dental crypts in prenatal stage

Purpose

To describe configurations of human prenatal mandibular, lingual canals using a limited-field cone beam computed tomography (CBCT) to examine their origin and anatomical significance.

Materials and methods

Nine fetal mandibles were examined using a CBCT. Mandibular maturity was assessed according to the mandibular size measured directly and image findings on development of dental crypts. Mandibular, lingual canals and the related foramina (mandibular, mental, and lingual foramina) were observed on axial, sagittal, and cross-sectional images. The horizontal position of mental and lingual foramina was assessed by direct observation using a loupe.

Results

In all nine mandibles, CBCT images depicted three separate mandibular canals, which individually occurred at the ramus area. One was a short canal directly connecting to the permanent molar crypt. The other two showed a parallel course, following the mandibular corpus toward the frontal area; the upper one connected to the mental foramen, and the lower one distributed anterior area of canine and incisor crypts. Lingual foramina were observed bilaterally in eight of nine mandibles, whose horizontal position was lingual against the crypt of deciduous canine. The lingual canals occurred from lingual foramina, and connected to the close deciduous tooth crypt or the mandibular canal distributing in the frontal area.

Conclusions

It was suggested human dentition could be developed by plural mandibular and lingual canals.     

Semicircular canals and agility: the influence of size and shape measures

The semicircular canals of the inner ear sense angular accelerations and decelerations of the head and enable co‐ordination of posture and body movement, as well as visual stability. Differences of agility and spatial sensitivity among species have been linked to interspecific differences in the relative size of the canals, particularly the radius of curvature (R) and the ratio of the canal plane area to streamline length (P/L). Here we investigate the scaling relationships of these two size variables and also out‐of‐plane torsion in the three semicircular canals (anterior, posterior and lateral), in order to assess which is more closely correlated with body size and locomotor agility. Measurements were computed from 3D landmarks taken from magnetic resonance images of a diverse sample of placental mammals encompassing 16 eutherian orders. Body masses were collected from the literature and an agility score was assigned to each species. The R and P/L of all three semicircular canals were found to have highly significant positive correlations with each other and no statistical difference was found between the slope of 2P/L against R and 1. This indicated that, contrary to initial hypotheses, there is little difference between 2P/L and R as measures of semicircular canal size. A measure of the in‐plane circularity of the canal was obtained by dividing 2P/L by R and out‐of‐plane torsion was measured as angular deviation from a plane of best fit. It was predicted that deviations from in‐plane and out‐of‐plane circularity would increase at small body size due to the constraints of fitting a proportionately larger canal into a smaller petrous bone. However, neither measurement was found to have a significant correlation with body mass, indicating that deviations from circularity (both in‐plane and out‐of‐plane) are not sufficient to alter P/L to an extent that would impact the sensitivity of the canals. 2P/L and R were both shown to be significantly correlated with locomotor agility. The posterior canal was the least correlated with agility, suggesting that it may be generally less closely aligned to the direction of movement than the anterior canal. Of the three canals, the lateral canal was the most highly correlated with agility. In particular, it could be used to distinguish between species that move in a largely 2D environment and those that locomote in 3D space (aerial, arboreal and aquatic species). This complements previous work suggesting that the lateral canal primarily commands navigation, whereas the vertical canals control reflex adjustments. It was also found that 2P/L is substantially better correlated with agility than is R in the lateral canal. This result is intriguing given the above finding that there is no statistical difference between 2P/L and R, and requires further investigation.     

Use of CBCT to investigate the root canal morphology of mandibular incisors

Purpose

To investigate the root canal morphology of mandibular incisors using cone-beam computed tomography (CBCT).

Materials and methods

A total of 353 patients with 1,412 healthy, well-developed mandibular incisors were enrolled. Radiographic examination by CBCT was conducted as part of their routine examination, diagnosis and treatment planning. The following observations were made using CBCT: (1) the number of roots; (2) the number of canals; (3) canal configuration according to Vertucci’s classification; (4) the position of root canal bifurcations.

Results

Two canals were found in 10.9 % of mandibular central incisors, 25.5 % of lateral incisors and in 18.2 % of all the 1,412 mandibular incisors. Significantly, more lateral incisors possessed two canals than central incisors (p < 0.05). Of the teeth with two canals, type III incisors were the most prevalent, followed by types II, IV and V. Furthermore, 37.7 % of teeth were found to have root canal bifurcations that were at or near to the cortical-middle third junction regions of the roots.

Conclusion

Routine mode CBCT imaging was clinically useful for detection of two canals and determines the position of root canal bifurcations in mandibular incisors.     

The Relationships of the Maxillary Sinus With the Superior Alveolar Nerves and Vessels as Demonstrated by Cone‐Beam CT Combined With μ‐CT and Histological Analyses

There are no available detailed data on the three‐dimensional courses of the human superior alveolar nerves and vessels. This study aimed to clarify the relationships of the maxillary sinus with the superior alveolar nerves and vessels using cone‐beam computed tomography (CT) combined with μ‐CT and histological analyses. Digital imaging and communication in medicine data obtained from the scanned heads/maxillae of cadavers used for undergraduate/postgraduate dissection practice and skulls using cone‐beam CT were reconstructed into three‐dimensional (3D) images using software. The 3D images were compared with μ‐CT images and histological sections. Cone‐beam CT clarified the relationships of the maxillary sinus with the superior alveolar canals/grooves. The main anterior superior alveolar canal/groove ran anteriorly through the upper part of the sinus and terminated at the bottom of the nasal cavity near the piriform aperture. The main middle alveolar canal ran downward from the upper part of the sinus to ultimately join the anterior one. The main posterior alveolar canal ran through the lateral lower part of the sinus and communicated with the anterior one. Histological analyses demonstrated the existence of nerves and vessels in these canals/grooves, and the quantities of these structures varied across each canal/groove. Furthermore, the superior dental nerve plexus exhibited a network that was located horizontally to the occlusal plane, although these nerve plexuses appeared to be the vertical network that is described in most textbooks. In conclusion, cone‐beam CT is suggested to be a useful method for clarifying the superior alveolar canals/grooves including the nerves and vessels. Anat Rec, 299:669–678, 2016. © 2016 Wiley Periodicals, Inc.     

Root canal sealers cause cytotoxicity and oxidative damage in hepatocytes

Elutable substances and degradation products from root canal sealers may gain access to periodontal tissue in many ways. The aim of this study was to investigate damage and oxidative stress caused by treatment with root canal sealers in primary cultured rat hepatocytes. Four root canal sealers were used: Canals, Sealapex, AH 26, and AH Plus. Toxicity was detected by assessing lactate dehydrogenase (LDH) leakage, and oxidative stress was determined by analysis of glutathione (GSH) levels. One-way analysis of variance was performed on the data. As the concentrations of sealer were increased, LDH leakage increased (p < 0.01). Increased GSH depletion accompanied LDH leakage increase. GSH levels were reduced to zero at a concentration of 0.05% for Canals and 0.10% for AH 26. These results confirmed the hypothesis that root canal sealers can cause cytotoxicity in hepatocytes. The Canals and AH 26 sealers can also cause oxidative stress in hepatocytes.     

改良根管糊剂一次法根充的疗效观察

目的 观察改良根管糊剂一次法根充治疗慢性尖周炎的临床疗效。方法 从门诊抽取慢性尖周炎病例，随机分为实验组和对照组，实验组行改良根管糊剂一次法根充，对照组采用常规疗法，观察两组1月、6月、12月后治疗的有效率。结果 实验组和对照组在治疗后1月、6月、12月后，有效率无显著性差异（P〉0．05）。结论 改良根管糊剂一次法根充治疗慢性尖周炎，方法简便，复诊次数少，可代替常规疗法。