Proximity of Premolar Roots to Maxillary Sinus: A Radiographic Survey Using Cone-beam Computed Tomography

Introduction

The proximity of the roots of the posterior maxillary teeth to the maxillary sinus is a constant challenge to the dental practitioner. Because the majority of studies have assessed the relationship regarding molars, the present study focused on premolars.

Methods

Cone-beam computed tomographic images of 192 patients were reconstructed in sagittal, coronal, and axial planes to quantify the distances between the root apices of the maxillary premolars and the adjacent maxillary sinus. Measurements were taken for each root, and data were correlated with age, sex, side, and presence of both or absence of 1 of the 2 premolars.

Results

A total of 296 teeth (177 first and 119 second premolars) were evaluated. The mean distances from buccal roots of the first premolars to the border of the maxillary sinus in the sagittal, coronal, and axial planes ranged from 5.15 ± 2.99 to 8.28 ± 6.27 mm. From palatal roots, the mean distances ranged from 4.20 ± 3.69 to 7.17 ± 6.14 mm. The mean distances of second premolars were markedly shorter in buccal roots between 2.32 ± 2.19 and 3.28 ± 3.17 mm and in palatal roots between 2.68 ± 3.58 and 3.80 ± 3.71 mm, respectively. The frequency of a premolar root protrusion into the maxillary sinus was very low in first premolars (0%–7.2%) but higher in second premolars (2.5%–13.6%). Sex, age, side, and presence/absence of premolars failed to significantly influence the mean distances between premolar roots and the maxillary sinus.

Conclusions

Based on the calculated mean distances of the present study, only few premolars (and if so second premolars) would present a risk of violating the border of the maxillary sinus during conventional or surgical endodontic treatment or in case of tooth extraction.     

上颌第一前磨牙根管颊舌向弯曲情况的研究

目的研究上颌第一前磨牙根管颊舌向的弯曲情况。方法选择100个上颌第一前磨牙为研究对象,开髓并充分暴露根管口后,将1个K型锉插入根管内直至根尖孔处。利用数字成像系统（RVG）拍摄每个牙的近远中向影像,采用Schneider法测量根管的弯曲角度,计算弯曲半径和弯曲部分长度。结果1）100颗上颌第一前磨牙共有176个根管,88个根管存在颊舌向弯曲,其中53个位于根尖1/3;21个根管存在“S”形弯曲,其第一弯曲多见于根中1/3,第二弯曲均见于根尖1/3处。2）颊腭侧根管弯曲情况无统计学差异（P>0.05）,但“S”形根管第二弯曲的弯曲情况更为复杂。3）弯曲角度与弯曲半径无相关关系（r=0.002,P>0.05）,但与弯曲部分长度呈正相关关系（r=0.489,P<0.01）。结论上颌第一前磨牙根管颊舌向弯曲发生率较高,其中“S”形根管的弯曲情况更为复杂。     

上颌第一前磨牙4根管1例

本文报告1例上颌第一前磨牙三根四根管的发现与诊断过程。通过临床诊断和操作过程中的细致观察和多角度的常规X线牙片,发现并定位了额外根管的存在,并借助锥形束CT和根管显微镜证实三根四根管的存在,最终在手术显微镜下完成了高质量的根管治疗。     

上颌第一前磨牙先天缺失尖牙异位萌出1例

<正>在生理状态下,牙萌出有一比较稳定的时间和顺序,若受到某些因素影响,则可致牙萌出异常、萌出困难、先天缺失或异位。我科于2012-08-20收治上颌第一前磨牙先天缺失、尖牙异位萌出1例,现报告如下。     

Maxillary molar root protrusion into the maxillary sinus: a comparison of cone beam computed tomography and panoramic findings

This study aimed to examine the prevalence of molar roots protruding into the maxillary sinus and to determine the panoramic radiographic signs as correlated with cone beam computed tomography (CBCT). CBCT images of 354 roots were assessed and classified into three types, according to the relationship between the root and maxillary sinus. The prevalence of root protrusion into the maxillary sinus was calculated then the panoramic images assessed. After excluding some unidentified roots on the panoramic images, 200 were investigated for panoramic signs, including (i) projection of the root apex into the sinus cavity, (ii) interruption of the maxillary sinus floor’s cortex, (iii) absence of periodontal ligament space, (iv) darkening of the involved root region, and (v) upward curving of the sinus floor. The respective correlation between the panoramic signs and CBCT types was assessed. Forty-six percent of roots showed protrusion into the sinus with the palatal root of the first molar having the greatest prevalence (33/200 roots). The panoramic signs ‘projection of the root apex in the sinus cavity’ and ‘darkening of the involved root apical region’ both strongly indicated root protrusion into the maxillary sinus (P < 0.05).     

Locating the MB2 canal in relation to MB1 in Maxillary First Molars using CBCT imaging

The aim of this study is to determine the location of MB2 in maxillary first molars in relation to the MB1 using the cone‐beam computed tomography (CBCT) imaging. In this retrospective study, electronic health records’ system was utilised to identify patients who acquired CBCT for the maxillary first molar as an imaging adjunct to their endodontic treatment. Data were evaluated, and statistical analysis was performed. For the initial treatment cases, the distance from MB1 to MB2 was 2.06 ± 0.52 mm. This did not change significantly for cases that were being retreated. Statistically significant differences were observed between the distances from MB1 to MB2 in males vs. female teeth with males demonstrating longer distances as compared to females. Variations in anatomy exist between patients but this study established some guidelines for clinicians to locate the MB2 canal orifices. This could potentially help with treating these teeth with minimal failure rates.     

上颌磨牙缺失患者上颌窦的CBCT影像学特点

目的 :观察上颌磨牙缺失患者上颌窦生理及病理CBCT影像学表现,并分析各类异常的发生率,为种植术前评估提供参考。方法:选择复旦大学附属中山医院口腔科及静安区牙病防治所,2014-01-01—2015-05-01期间,收治的上颌磨牙缺失患者CBCT影像学资料202例,共404侧上颌窦。由2名研究人员对资料进行研究分析,观察项目分为3类:正常上颌窦、上颌窦炎、上颌窦囊肿。测量3种类型病例缺牙区窦嵴距、上颌窦的宽度、外侧骨壁厚度、外侧骨壁血管位置与直径,采用SPSS17.0软件进行统计分析。结果:404侧上颌窦中,正常上颌窦185侧(45.80%);上颌窦炎118侧(29.20%);上颌窦囊肿101侧(25.00%)。结论:上颌窦异常影像诊断发生率最高者为上颌窦炎,其次为上颌窦囊肿;不同上颌窦影像诊断类型间窦嵴距、上颌窦的宽度、外侧骨壁厚度、外侧骨壁血管位置与直径差异均无统计学意义(P>0.05)。     

The Incidence of Second Mesiobuccal Canals Located in Maxillary Molars with the Aid of Cone-beam Computed Tomography

Introduction

Many endodontic treatment failures in maxillary molars result from missed second mesiobuccal (MB2) canals. An MB2 canal orifice is present in as many as 95% of maxillary molars, but these canals are not always located during endodontic procedures. Additional tools, such as cone-beam computed tomographic (CBCT) imaging, may be needed to locate these canals in maxillary molars. Hence, the aims of this study were to investigate the frequency of use of CBCT imaging during the treatment of maxillary molars and to evaluate the influence of its use on the detection of MB2 canals.

Root Canal Morphology of 116 Maxillary Second Premolars by Micro–Computed Tomography in a Mixed Swiss-German Population with Systematic Review

IntroductionThe aim of this investigation was to examine the root canal system morphology of maxillary second premolars (Mx2Ps) of a Swiss-German population by means of micro–computed tomography and provide systematic review of the root canal configuration (RCC) literature of Mx2Ps.MethodsThe RCC, main foramina as well as accessory canals and foramina frequency of 116 Mx2Ps, were investigated by means of micro–computed tomography and 3-dimensional software imaging. The RCC from the coronal to apical thirds of the root as well as the main foramina number were described by using a four-digit system code. The literature review follows the PRISMA guideline analyzing randomized controlled trials and cross-sectional, cohort, comparative, validation, and evaluation studies on RCC in Embase, grey literature, PubMed, and Scopus.ResultsMost frequently observed RCCs of Mx2Ps were 1-1-1/1 (35.3%), 1-1-1/2 (21.6%), and 2-1-1/1 (14.7%). Another 11 less frequent RCCs were observed. All Mx2Ps had 1 root. One main foramen was observed in 59.5% and two in 37.9%. Accessory foramina were observed in 46.6%. Thirty-one percent of the Mx2Ps showed accessory canals. One connecting canal between the buccal and palatal was observed in 12.1%.ConclusionsDetailed RCC information of Mx2Ps in a Swiss-German population and the results of a systematic literature review of different populations and research methods used to investigate root canal morphology and configuration of Mx2Ps are given. Within the limitations of the study, a high RCC, connecting and accessory canals variability occur in maxillary second premolars.     

Resin Composite Core and Fiber Post Improved the Fracture Parameters of Endodontically Treated Maxillary Premolars with Wedge-shaped Cervical Lesions

IntroductionThe aim of this study was to evaluate the fracture resistance and fracture patterns of endodontically treated maxillary premolars with wedge-shaped cervical lesions restored with a resin composite core with or without a fiber post under nonaxial loading.MethodsSixty extracted human maxillary premolars with 2 root canals were randomly allocated into 4 groups (n = 15). Forty-five teeth were prepared with a wedge-shaped lesion at the buccal cervical area and root canal treatment. There were 3 restoration groups: no restoration, restoration with a resin composite core, and restoration with a resin composite core and a fiber post. Intact teeth served as the control group. All teeth were subjected to thermocycling and cyclic loading. A 45° compressive load was applied to the palatal plane of the buccal cusp until tooth fracture. The fracture resistance and facture patterns were analyzed using 1-way analysis of variance and the chi-square test (α = 0.05), respectively.ResultsThe no restoration group demonstrated the lowest fracture resistance and was significantly different from the other groups (P < .001). The intact teeth presented the highest fracture resistance, which was not significantly different from the restoration with a resin composite core and a fiber post group (P > .05). The failure patterns were significantly different between groups (P < .001). Most intact teeth fractured coronally to the cementoenamel junction level, whereas most teeth in the other groups fractured at the gingival margin of the cervical lesion.ConclusionsEndodontically treated maxillary premolars with wedge-shaped cervical lesions restored with fiber posts and a resin composite cores had a fracture resistance equivalent to intact teeth. However, their fracture patterns were not improved by the fiber post and a resin composite core.     

13例下颌前磨牙C形根管的锥束CT分析

目的：采用锥束CT（CBCT）分析下颌前磨牙C形根管形态。方法：选取13例22个下颌前磨牙C形根管患者的CBCT数据,使用NNT软件分析下颌前磨牙C形根管的形态、根面沟、根管分叉和双侧根管对称性。结果：下颌第一前磨牙根管C1型为23.8%、C2型61.9%、C3型14.3%,下颌第二前磨牙1例C3型。61.9%的下颌第一前磨牙C形根管在根中1/3分叉,下颌第二前磨牙在根冠1/3处根管分叉。下颌第一前磨牙C形根管对称率为61.5%,下颌第二前磨牙无对称性发生。结论：下颌前磨牙C形根管解剖结构复杂,CBCT可准确研究根管系统。     

成人上下颌双侧前磨牙区7颗多生牙1例

上下颌前磨牙区发生非综合征性多颗多生牙较少见。本文报道1例成年男性上下颌双侧前磨牙区7颗多生牙病例,并回顾相关文献,讨论前磨牙区多颗多生牙的发病原因、临床表现及治疗方法。     

下颌第二前磨牙双根3根管治疗1例

下颌前磨牙根管形态较为复杂,可能存在多根管,给根管治疗带来难度.插诊断丝的X线片,和多角度投射有助于发现其他根管.CBCT可更加直观的看到根管形态,从而有利于分析根管的分布.报告1例CBCT在下颌第二前磨牙双根3根管治疗中的诊断作用.     

Maxillary incisor inclination of skeletal Class III patients treated with extraction of the upper first premolars and two-jaw surgery: Conventional orthognathic surgery vs surgery-first approach

Objective:To investigate the differences in the amount and pattern of the maxillary incisor (MXI) inclination change in skeletal Class III patients treated with extraction of the maxillary first premolars (MXP1) and two-jaw surgery (TJS) between conventional orthognathic surgery (COS) and surgery-first approach (SFA).Materials and Methods:The study included 60 skeletal Class III patients who had normal maxillary position, prognathic mandible, and mild crowding in the maxillary arch (≤4 mm). The patients were divided into group 1 (COS, n  =  36) and group 2 (SFA, n  =  24). Lateral cephalograms were taken before treatment (T0), 1 month before surgery (T1), within 1 month after surgery (T2), and after debonding (T3) for COS patients and at T0, T2, and T3 for SFA patients. After measurement of the skeletodental variables, statistical analyses were performed.Results:During T0–T2, the amount of MXI inclination change (ΔU1-SN) in group 1 was significantly larger than that in group 2 (−12.8° vs −4.4°; P < .001). During T2–T3, ΔU1-SN in groups 1 and 2 occurred in opposite directions (3.8° vs −5.9°; P < .001). However, the total amount of ΔU1-SN during T0–T3 was not different between groups 1 and 2 (−9.0° vs −10.3°). At T3 the U1-SN values for groups 1 and 2, respectively, moved closer to normal according to the values of the normal range rate (all 83%), relative percentage ratio (102.4% and 100.1%), and achievement ratio (77.7% and 97.8%).Conclusions:The results of this study might provide basic data for predicting the amount and pattern of MXI inclination change in SFA for skeletal Class III TJS patients.     

藏族和汉族上颌第一恒磨牙近中颊根的CBCT对比研究

目的:比较藏族和汉族上颌第一恒磨牙近中颊根数据,为临床提供参考.方法:随机收集藏族和汉族患者上颌第一恒磨牙近中颊根CBCT图像440例,测量根长、弯曲度、弯曲位置、是否有第二近颊根(MB2)、MB-MB2距离.结果:藏族第一恒磨牙近中颊根长度较汉族长,差异有统计学意义(P<0.05).近中颊根根管弯曲度比较,藏汉族有统...     

Identification and Characterization of a Previously Undiscovered Anatomical Structure in Maxillary Second Molars: The Palato-Mesiobuccal Canal

IntroductionThis report aims to communicate the discovery of a novel anatomy in a 3-rooted maxillary second molar, named as palato-mesiobuccal canal.MethodsThe tooth selected for this report was found incidentally as a result of a study on extracted maxillary molars that was being conducted for an unrelated purpose and involved hundreds of teeth. This 3-rooted maxillary second molar was scanned using a micro–computed tomography device set at a pixel size of 13.68 μm. The images were reconstructed with previously tested parameters resulting in the acquisition of 1655 axial cross-sections. Three-dimensional (3D) models of the internal and external anatomies were generated in Standard Tessellation Language (STL) format and were texturized to simulate the pulp tissue. The inner structure of the tooth was analyzed through the axial cross sections and the 3D volume was qualitatively evaluated.ResultsThe analysis of the 3D models revealed that the maxillary second molar under examination has 3 independent roots and 4 root canals. Each root (mesiobuccal, distobuccal, and palatal) contains 1 canal, while the fourth canal follows a unique path, originating in the coronal third of the palatal canal and proceeding in a buccal direction ultimately exiting through an independent foramen at the apex of the mesiobuccal root, near the mesiobuccal canal.ConclusionsThis brief communication reports the discovery of a novel anatomy in a 3-rooted maxillary second molar, named as palato-mesiobuccal canal, and provides important insights into the complexity of the root canal system in this group of teeth.     

双下颌管的CBCT观察

目的 :应用CBCT对下颌骨双下颌管情况进行观察和研究,统计其发生概率,为下颌后牙区种植及下颌第三磨牙拔除提供参考。方法:收集2012—2014年上海市第六人民医院口腔科就诊病人200例,征得患者同意登记个人信息并拍摄CBCT。观察患者有无双下颌管,描述其走行特征并进行统计学分析。结果:双下颌管发生率为29.5%,并发现三分支下颌管2例。下颌管分支根据走行方向分成3类:磨牙管、颊舌侧管、前行管。其中磨牙管发生率为20%,颊舌侧管发生率为8%,前行管发生率72%。结论:经CBCT观察发现,双下颌管有较高发生率,在下颌后区进行种植术等各种手术治疗前应拍摄CBCT,警惕双下颌管的存在,防止严重并发症的发生。     

无托槽隐形矫治技术拔除前磨牙的支抗设计与临床控制

无托槽隐形矫治技术的诞生满足了人们对于牙齿正畸美观、舒适的需求,成为了成人和青少年很好的正畸治疗手段。在最初使用无托槽隐形矫治器时,它只能被用于排齐牙列等简单正畸治疗。随着无托槽隐形矫治器生产商和临床医生对完成病例不断回顾和研究,当前无托槽隐形矫治技术体系不断完善并逐渐精准化,其中对于拔除前磨牙的无托槽隐形矫治也趋于成熟。本文将对无托槽隐形矫治技术拔除前磨牙的支抗设计和临床控制进行综述。     

下颌第一前磨牙非单根管系统的形态学研究

目的：采用锥形束CT（CBCT）分析下颌第一前磨牙非单根管系统的解剖形态。方法：选取20颗具有非单根管系统下颌第一前磨牙离体牙标本,CBCT 扫描数据,使用三维重建软件分析下颌第一前磨牙牙根的数目、根面沟情况及根管形态。结果：20颗下颌第一前磨牙非单根管系统中,单根及融合单根17颗（85．0％）、双根3颗（15．0％）。根面沟发生率为95．0％,好发于近中舌侧、舌侧。根管形态发生率分别为双根管Ⅲ型（1－2－1）25．0％、Ⅴ型（1－2）5．0％,三根管Ⅷ型（3－3）15．0％、Ⅸ型（3－4）型5．0％、C形9例45．0％、环形1例5．0％,其中C形发生率最高。结论：下颌第一前磨牙非单根管系统解剖形态复杂。     

Management of Cleft Maxillary Hypoplasia with Anterior Maxillary Distraction: Our Experience

Maxillary hypoplasia is a common developmental problem in cleft lip and palate deformities. Since 1970s these deformities have traditionally been corrected by means of orthognathic surgery. Management of skeletal deformities in the maxillofacial region has been an important challenge for maxillofacial surgeons and orthodontists. Distraction osteogenesis is a surgical technique that uses body’s own repairing mechanisms for optimal reconstruction of the tissues. We present four cases of anterior maxillary distraction osteogenesis with tooth borne distraction device-Hyrax, which were analyzed retrospectively for the efficacy of the tooth borne device-Hyrax and skeletal stability of distracted anterior maxillary segment.