下颌第二恒磨牙牙根及根管形态的锥形束CT研究

目的 使用锥形束CT扫描评估下颌第二恒磨牙牙根和根管解剖形态.方法 收集354例患者双侧下颌第二恒磨牙的锥形束CT图像,统计下颌第二恒磨牙牙根数目、根管数目和构型,以及C形根管的发生率.结果 下颌第二恒磨牙以双根最多,发生率为57.34%,C形根的发生率为38.28%;双根者近中根多为2-2型(80.54%),远中根多为1-1型(96.06%);C形根管的发生率为25.99%,左、右下颌的发生率没有统计学差异(P>0.05).结论 下颌第二恒磨牙牙根和根管解剖形态复杂多样,锥形束CT能为根管治疗提供参考.     

乳磨牙根管复杂性的CBCT研究

目的 利用CBCT研究上海地区儿童乳磨牙牙根数目及根管系统解剖形态,为临床诊断提供影像学依据.方法 选取167例患者(4～7岁)CBCT扫描图像,测量乳磨牙牙根数目、牙齿长度,分析根管数目和类型,并对相应结果做统计学分析.结果 ①上颌第一乳磨牙牙根中三根占50.30％,双根占47.59％.上颌第二乳磨牙牙根三根检出率99.37％.下颌第一、二乳磨牙牙根以双根居多,分别为91.48％、72.95％.②上颌乳磨牙腭根的牙齿长度较颊根长;下颌第一乳磨牙近、远中根的牙齿长度未见明显差异,下颌第二乳磨牙近中根的牙齿长度较远中根长.③上颌第一乳磨牙根管数目以三根管居多,为97.59％.上颌第二乳磨牙三根管占87.13％,四根管占12.27％.上颌乳磨牙的根管类型为Ⅰ型、Ⅱ型、Ⅲ型和Ⅳ型,以Ⅰ型居多.④下颌第一乳磨牙中三根管占41.96％(近中根管为双根管的占39.10％,远中根管为双根管的占60.90％),四根管为39.75％,双根管18.30％.下颌第二乳磨牙中多为四根管,占83.28％.下颌乳磨牙的根管类型主要是Ⅰ型和Ⅳ型.结论 乳磨牙牙根及根管解剖结构复杂多变、变异率高.上颌第二乳磨牙和下颌第一乳磨牙根管结构变异率较其他牙位高,结合CBCT有利于明确诊断和治疗.     

乳磨牙根管复杂性的CBCT研究

目的 利用CBCT研究上海地区儿童乳磨牙牙根数目及根管系统解剖形态,为临床诊断提供影像学依据.方法 选取167例患者(4～7岁)CBCT扫描图像,测量乳磨牙牙根数目、牙齿长度,分析根管数目和类型,并对相应结果做统计学分析.结果 ①上颌第一乳磨牙牙根中三根占50.30％,双根占47.59％.上颌第二乳磨牙牙根三根检出率99.37％.下颌第一、二乳磨牙牙根以双根居多,分别为91.48％、72.95％.②上颌乳磨牙腭根的牙齿长度较颊根长;下颌第一乳磨牙近、远中根的牙齿长度未见明显差异,下颌第二乳磨牙近中根的牙齿长度较远中根长.③上颌第一乳磨牙根管数目以三根管居多,为97.59％.上颌第二乳磨牙三根管占87.13％,四根管占12.27％.上颌乳磨牙的根管类型为Ⅰ型、Ⅱ型、Ⅲ型和Ⅳ型,以Ⅰ型居多.④下颌第一乳磨牙中三根管占41.96％(近中根管为双根管的占39.10％,远中根管为双根管的占60.90％),四根管为39.75％,双根管18.30％.下颌第二乳磨牙中多为四根管,占83.28％.下颌乳磨牙的根管类型主要是Ⅰ型和Ⅳ型.结论 乳磨牙牙根及根管解剖结构复杂多变、变异率高.上颌第二乳磨牙和下颌第一乳磨牙根管结构变异率较其他牙位高,结合CBCT有利于明确诊断和治疗.     

乳磨牙根管复杂性的CBCT研究

目的 利用CBCT研究上海地区儿童乳磨牙牙根数目及根管系统解剖形态,为临床诊断提供影像学依据.方法 选取167例患者(4～7岁)CBCT扫描图像,测量乳磨牙牙根数目、牙齿长度,分析根管数目和类型,并对相应结果做统计学分析.结果 ①上颌第一乳磨牙牙根中三根占50.30％,双根占47.59％.上颌第二乳磨牙牙根三根检出率99.37％.下颌第一、二乳磨牙牙根以双根居多,分别为91.48％、72.95％.②上颌乳磨牙腭根的牙齿长度较颊根长;下颌第一乳磨牙近、远中根的牙齿长度未见明显差异,下颌第二乳磨牙近中根的牙齿长度较远中根长.③上颌第一乳磨牙根管数目以三根管居多,为97.59％.上颌第二乳磨牙三根管占87.13％,四根管占12.27％.上颌乳磨牙的根管类型为Ⅰ型、Ⅱ型、Ⅲ型和Ⅳ型,以Ⅰ型居多.④下颌第一乳磨牙中三根管占41.96％(近中根管为双根管的占39.10％,远中根管为双根管的占60.90％),四根管为39.75％,双根管18.30％.下颌第二乳磨牙中多为四根管,占83.28％.下颌乳磨牙的根管类型主要是Ⅰ型和Ⅳ型.结论 乳磨牙牙根及根管解剖结构复杂多变、变异率高.上颌第二乳磨牙和下颌第一乳磨牙根管结构变异率较其他牙位高,结合CBCT有利于明确诊断和治疗.     

辽宁地区汉族人下颌第二恒磨牙牙根和根管数目的锥形束CT研究

目的：利用锥形束CT（CBCT）扫描评估辽宁地区汉族人下颌第二恒磨牙牙根和根管数目的情况。方法：调取于我院口腔科行CBCT扫描患者的图像资料,统计分析下颌第二恒磨牙牙根和根管数目的情况。结果：在900例下颌第二恒磨牙中,双根的发生率为51．22％,其中82％的近中根内为双根管,100％的远中根内为单根管;三根的发生率为2．18％;融合根的发生率为46．6％,其中完全融合的锥形根占5．71％,不完全融合的C形根（C型根管）占40．89％,C型根管发生率在男女性别间差异无统计学意义（p〉0．05）,以双侧对称性分布较多,单侧发生率以右侧为多。结论：在辽宁地区汉族人中,下颌第二恒磨牙以双根或融合根居多,c形根（C型根管）的发生率较高。     

锥束CT评价下颌第二恒磨牙牙根和根管解剖形态研究

目的:用锥束CT扫描评估下颌第二恒磨牙牙根和根管解剖形态。方法:收集305例锥束CT影像,分别记录病人的性别、牙位、牙根和根管的数目和形态,采用Vertucci分类法对根管构型进行分类描述。结果:在受检样本中,47.21%的下颌第二恒磨牙为融合根,C形根和C型根管的检出率均为41.64%。在两个根的下颌第二恒磨牙中,66.03%近中根管是Ⅳ型,92.31%的远中根管是I型。左、右侧下颌第二恒磨牙C形牙根和C型根管的发生率没有统计学差异(P>0.05),男性和女性的C形牙根和C型根管的发生率也没有统计学差异(P>0.05)。结论:中国西部人群中,下颌第二恒磨牙通常为双根或融合根,C形牙根和C型根管的发生率均较高。     

西北地区中国人下颌第一恒磨牙牙根根管数目的锥束CT研究

目的:利用锥形束CT(CBCT)观察分析西北地区中国人下颌第一恒磨牙牙根和根管数目及其变异情况,以期为临床治疗提供参考。方法:随机调取来我院放射科行CBCT检查的病人图像资料,统计分析下颌第一恒磨牙牙根和根管数目及其分布情况。结果:共获取800例病人1 600个下颌第一恒磨牙CBCT图像数据。下颌第一恒磨牙2个牙根的发生率为72.69%(1163/1600),其中2根2管的发生率3.27%,2根3管的发生率73.00%,2根4管的发生率23.73%;3个牙根的发生率为27.31%(437/1 600),其中3根3管的发生率4.12%,3根4管的发生率95.88%。下颌第一恒磨牙远中舌根的个体发生率为33.75%(270/800)。男女性别间发生率无统计学差异(P>0.05)。下颌第一恒磨牙远舌根双侧对称性的发生率61.85%(167/270),且右侧高于左侧,差异有统计学意义(P<0.05)。结论:下颌第一恒磨牙牙根和根管数目以及解剖形态存在多样性,CBCT影像可为临床根管治疗术提供可靠的依据。     

下颌第二磨牙龋损状况临床分析

目的: 统计分析下颌第二磨牙龋坏始发部位及严重程度, 并分析其与性别、年龄及下颌第三磨牙萌出状况的关系。方法: 采用临床与X线检查对481例下颌第二磨牙龋坏患者进行统计调查, 应用SPSS 13.0软件包对结果进行χ2检验。结果: 下颌第二磨牙龋坏多始发于面和远中邻面, 其次为颊面, 发生率分别为33.8%、33.2%、24.4%;累及牙髓的龋坏最多, 占49.7%, 深龋、浅中龋分别占31.7%、18.6%;男、女性别在龋坏部位分布总体上无显著差异;年龄与下颌第二磨牙的龋坏部位分布及严重程度有显著的相关性, 随着年龄增大, 面和远中邻面龋坏增多, 程度加重;下颌第三磨牙萌出状况对下颌第二磨牙龋坏影响显著。结论: 下颌第二磨牙始发龋坏牙面以面及远中邻面最多, 龋损程度严重, 年龄、下颌第三磨牙萌出状况与龋坏状态关系密切。预防性拔除异常萌出的下颌第三磨牙及定期检查, 是预防和早期治疗下颌第二磨牙龋坏的有效措施。     

苏州地区汉族人上颌第一、二恒磨牙牙根变异的锥形束CT观察

目的揭示苏州地区汉族人群上颌第一、二恒磨牙各型牙根变异的发生状况。方法调取苏州口腔医院放射科接受锥形束CT扫描的汉族患者的CT图像资料,患者共257人。观察上颌恒磨牙牙根变异的牙齿发生率、个体发生率及双侧分布状况。率的比较采用卡方检验,左、右侧的相关性采用Spearman等级相关性分析。结果上颌第一恒磨牙融合根的牙齿发生率3.1%(15/484)。上颌第二恒磨牙3根的牙齿发生率为69.7%(285/409),双侧共同发生率为60.3%(117/194),男、女组间以及双侧差异均无统计学意义(P>0.05);牙根变异以2个颊侧根融合最常见(11.7%),其次为融合性单根(10.5%),近颊根与腭根融合的发生率为4.9%。牙根变异在左、右同名牙间具有显著的相关性,相关系数rho=0.607(P<0.01)。结论上颌第一恒磨牙较少发生牙根变异;上颌第二恒磨牙融合根在苏州地区汉族人中具有较高的发生率,掌握其分布特点具有重要的临床意义。     

中国西北地区人群恒牙牙根变异的锥束CT观察

目的:分析西北地区汉族人恒牙牙根变异的规律。方法:调取在西安市第四军医大学口腔医学院放射科接受锥束CT扫描病人的CT图像资料,病人共500人(男性246例,女性254)。观察并计算各类牙根变异的牙齿发生率和个体发生率。男女组间、双侧同名牙间率的比较采用卡方检验,左右侧不对称性采用Spearman等级相关性分析。结果:双根型下颌尖牙的发生率为0.63%(3/474人)。上颌第一前磨牙多根的发生率为30.28%(132/436人),下颌第一前磨牙Tomes根为13.45%(60/446人)。双侧上颌第二磨牙3根的发生率为57.48%(219/381人),下颌第一磨牙远舌根变异为31.98%(134/419人),下颌第二磨牙融合根为41.77%(165/395人)。除3根型下颌第一磨牙外,上述其他各项牙根变异性别差异均具有统计学意义(P<0.05)。结论:熟悉掌握汉人恒牙的牙根变异规律具有重要的临床价值。     

Progression of proximal caries in the mixed dentition: a 4-year prospective study

PURPOSE: The purpose of this study was to investigate the survival rate and median survival time of different stages of proximal caries in 196 children aged 6 to 8 years at baseline examination. METHODS: Proximal caries and its progression were diagnosed from bitewing radiographs taken at 1-year intervals over a period of 4 years. The mesial surface of the first permanent molars, the mesial and distal surfaces of the first and second primary molars, and the distal surface of the primary canine were examined. Sound surfaces, caries lesions in the external- and internal-half of the enamel and external-, middle-, and internal-third of the dentin, as well as filled, extracted, and exfoliated teeth were recorded. A life table analysis was performed to estimate the annual and cumulative survival rates and the median survival time of each state of proximal lesions. RESULTS: For the sound mesial surfaces of the first permanent molars, the cumulative survival rate was 76% and the median survival time was over 48 months. The corresponding values for the external-half of the enamel lesions were 41% and 45 months. Regarding the sound mesial and distal surfaces of the primary teeth, the cumulative survival rate was 92% and the median survival time was over 48 months. The corresponding values for the external and internal-half of the enamel lesions were 40% and 31 months, and 29% and 22 months, respectively. The value of the cumulative survival rate for the external-third of dentin lesions was 42%, with a median survival time of 34 months, and the value for the middle-third of the dentin was 38% with a median survival time of 17 months. CONCLUSIONS: The risk of developing carious lesions in the sound proximal surfaces of both primary teeth and first permanent molars is low during the mixed dentition period; the progression of the external-half of enamel lesions of the first permanent molars is low for the first 3 years and becomes faster thereafter; and as the time period that the tooth exposed to cariogenic factors increases, the progression of the proximal caries is faster for all stages of the lesion in the primary teeth.     

Root canal configuration and the prevalence of C-shaped canals in mandibular second molars in an Iranian population

A total of 139 extracted mandibular second molars were injected with India ink and demineralized. They were made clear and transparent with methyl salicylate, and the anatomy of their canals was studied. It was found that 86.3% of mandibular second molars had two roots, 9.3% had one root, and 4.3% had three roots. Ninety percent of the mesial roots of the mandibular second molars with two roots had two canals (predominantly with a type II or III configuration), and 77.5% of the distal roots of these teeth had one canal (predominantly with a type I configuration). Among the mandibular second molars, 7.2% had C-shaped canals and these configurations were seen mostly in single-rooted mandibular second molars. The results of this study indicate that mandibular second molar teeth have many variations in the number of roots and the morphology of their canals. Therefore it should not be assumed that all mandibular second molar teeth have two roots and three canals.     

Caries prevalence in the deciduous dentition of a mediaeval population from the Southwest of Scotland

The prevalence, distribution and location of dental caries were studied in the deciduous dentition of 185 skeletons aged between 6 months and 13 years from a large, mostly mediaeval, cemetery, where successive phases of use could be distinguished. The main phases dated from 1240 to 1440 AD. During this period, no consistent trend or pattern of caries was identified, but there was a significantly higher caries prevalence in the age band 6–12.9 years than in the age band 0.1–5.9 years. The caries prevalence in the juveniles from the earlier Northumbrian, or Anglo-Saxon, phase of the cemetery was higher than in any mediaeval phase group, with mostly approximal surfaces affected. In the mediaeval population, first deciduous molars generally showed lower caries prevalence than second deciduous molars, significantly lower for the older age band, and maxillary molars consistently showed lower levels than mandibular molars. The highest caries rate, shown by mandibular second molars in the older age band, was 7.9%. In deciduous molars, the occlusal surface was most frequently affected by caries, whereas in the permanent molars of the same population the approximal surfaces had shown the highest level of attack. The overall caries prevalence in deciduous teeth in the mediaeval population of Whithorn was 2.3% of the teeth present, lower than the levels found in previous Scottish and English population groups, including a small assemblage of children from the Scottish sites of Elcho, Southwick and Kirkhill.     

Use of cone-beam computed tomography to evaluate root and canal morphology of mandibular first and second molars in Turkish individuals

Objective: The aim of this study was to investigate the root and canal morphology of mandibular first and second molars in a Turkish population by using cone beam computed tomography (CBCT). Study design: CBCT images of mandibular first (n = 823) and second molar (n = 925) teeth from 605 Turkish patients were analyzed. The root canal configurations were classified according to the method of Vertucci. Results: The majority of mandibular molars (95.8% of first molars, 85.4% of second molars) had two separate roots; however, three roots were identified in 2.06% of first molars and 3.45% of second molars. C-shaped canals occurred 0.85% of first molars and 4.1% of second molars. Three canals were found in 79.9% of first molars and 72.8% of second molars. Most distal roots had a simple type I configuration, whereas mesial roots had more complex canal systems, with more than one canal. The most common root morphology of first and second molars is the two rooted morphology with three canals. Both the mesial and distal roots showed wide variations in canal anatomy with type IV and type I canal configuration predominating in the mesial and distal roots, respectively. Conclusion: Vertucci type I and IV canal configurations were the most prevalent in the distal and mesial roots, respectively, of both the mandibular first and second permanent molar teeth. Key words:Cone-beam CT, Turkish, mandibular molars, root and canal morphology.     

下颌智齿阻生类型及其邻牙远中邻面患龋情况的对称性初探

目的 调查下颌第三磨牙生长情况的对称性及其对相邻第二磨牙远中邻面龋患病情况的影响,为临床早期预防性拔除下颌智齿提供依据。方法 纳入2019年11月1日至2019年11月23日在上海交通大学医学院附属仁济医院口腔科拍摄的全景片196张,调查其双侧下颌第三磨牙的对称性,通过卡方检验分析不同阻生类型的下颌第三磨牙与相邻第二磨牙远中邻面龋患病情况之间的关系。结果 双侧下颌第三磨牙对称者187例,占比95.41%。Winter分类中垂直阻生对称性（79.2%）显著高于近中阻生（47.6%）与水平阻生（59.1%）（P=0.001）; Winter分类为近中阻生（46.4%）和水平阻生（38.4%）的下颌第三磨牙,其相邻第二磨牙远中邻面龋发生率显著高于垂直阻生（23.6%）（P=0.001）。结论 下颌智齿具有对称性;为预防相邻第二磨牙远中邻面龋,近中阻生及水平阻生的下颌第三磨牙应在临床上早期预防性拔除。     

A survey of approximal root concavities in an ethnic Chinese population

Eight hundred and forty teeth were surveyed, 60 approximal surfaces for each tooth type being studied. Approximal root concavities were completely absent in maxillary central incisors, in contrast with mandibular central incisors of which 73% had concavities on mesial surfaces and 93% on distal surfaces. Similarly, a markedly higher prevalence was found for mandibular lateral incisors and canines. However, mandibular first and second molars had fewer approximal concavities than their maxillary counterparts. In maxillary teeth, concavities were more frequent on distal surfaces, while for mandibular teeth no definite pattern was seen. In both maxillary and mandibular teeth, approximal concavities often started in enamel, extending down to the root surface. There were differences in the approximal root topography of Chinese teeth in comparison with other populations.     

Dental plaque and caries on permanent first molar occlusal surfaces in relation to sagittal occlusion

This study examines the influence of sagittal occlusion on occlusal plaque formation in permanent first molars (PFM) in 72 7–10-yr-olds before loss of primary second molars. Of a total of 288 PFM, 140 (49%) were sealed and 23 (8%) filled. Occlusal plaque was recorded at two levels of examination: 1) visible plaque on the entire surface and 2) detailed macromorphologic mapping. Enamel caries was recorded after professional tooth cleaning. After 48 h without tooth brushing, plaque examinations were repeated. Stone models were used for 1) identification of interocclusal contact areas and 2) classification of sagittal molar occlusion. The detailed mapping of plaque on unfilled surfaces showed a clear pattern of preferential locations related to the macromorphology of the occlusal surfaces. Active caries was restricted to those anatomic structures where plaque accumulated. 48-h median plaque values on mandibular molars in normal and with one cusp distal occlusion were significantly lower ( P < 0.01) compared to surfaces in 1/4, 1/2 and 3/4 distal molar occlusion. Maxillary molars with normal and with 1 cusp distal occlusion had lower median plaque values than other sagittal occlusion categories. In general, however, plaque scores were higher in maxillary teeth because more than 2/3 of these teeth were without occlusal contact in the distal part. Mandibular occlusal surfaces in normal and with one cusp distal occlusion had significantly fewer active lesions than teeth with 1/4, 1/2 and 3/4 cusp distal occlusion. The significant influence of variations in sagittal molar relation on occlusal plaque formation and caries initiation occurring in fully erupted PFM before loss of primary second molars thus supports the view that physical forces operating during mastication are an important factor for colonization and growth of bacteria with cariogenic potential.     

Root canal configurations of third molar teeth. A comparison with first and second molars in the Turkish population

The purpose of the current study was to determine the similarities of maxillary and mandibular third molars with the other molar teeth. A total of 2016 extracted maxillary and mandibular permanent teeth were evaluated. The teeth were divided into six groups. The teeth were stored in 5% nitric acid solution for 7 days, then placed in increasing concentrations of ethyl alcohol. The teeth were rendered transparent by immersion in xylene solution for 4 days until complete transparency was achieved. Three roots were present in 93.0% of the maxillary molars, and 91.3% of the second molars. Among the maxillary third molars, 35.5% were single-rooted and 24.9% of the mandibular third molars had single roots. Double roots were present in 69.2% of the mandibular third molars, and 5.4% had three roots. Four new root canal configurations were encountered in this study. The root canal configurations of the mandibular and maxillary teeth showed similarities with the results of other studies performed in different populations.     

Cervical enamel projections as an etiologic factor in furcation involvement.

Two thousand molars in 200 East Indian skulls were examined for the occurrence, location, and grade of cervical enamel projections. The relationship between the enamel projections and furcation involvements was studied. Several findings resulted. The incidence of cervical enamel projections in molars was 32.6%. The incidence of cervical enamel projections varied between molars. The mandibular second molars showed the highest incidence of enamel projections (51.0%), followed by the maxillary second molars (45.6%). The lowest incidence was seen in the maxillary first molars (13.6%). Grade 1 enamel projections were the most frequently encountered. Cervical enamel projections occurred most frequently on the buccal surfaces of teeth. There was a positive, statistically significant relationship between tooth surfaces with grade 2 and 3 enamel projections and periodontally involved furcations. However, no etiologic relationship was found between grade 1 projections and furcation involvements. There seems to be a physiologic relationship between bone and enamel projections. The alveolar crest has a tendency to follow the outline of the enamel projection, and a channel much wider than a normal periodontal membrane space accommodates the enamel projection as it extends toward the furcation. The results indicate that when cervical enamel projections are severe enough to approach or enter the furcation area (grades 2 and 3), they may be an etiologic factor in the breakdown of these furcations.