Relationship between CBCT and panoramic images of the morphology and angulation of the posterior mandibular jaw bone

Purpose

We determined actual bucco-lingual angulation values and morphological variations of residual bone in the mandibular posterior edentulous region using cone-beam computed tomography (CBCT) and panoramic radiography. A second aim was to investigate whether it was possible to predict bone morphology from panoramic radiographs.

Methods

Data were collected from 77 consecutive patients referred for both CBCT and panoramic radiography in our department. Two-dimensional and three-dimensional images of the probable implant placement region were investigated. The bucco-lingual angulation values and crest type were determined directly from the cross-sectional images of the posterior edentulous region. The edentulous region was divided into three groups: second premolar, first molar, or second molar region. The observations were evaluated by the computer software, SPSS 22.0 (SPSS Inc. Chicago, USA). The crest type was classified into three groups: type U, type C, or type P. Kappa statistics, Kolmogorov–Smirnov tests, ANOVA, and Kruskal–Wallis tests were used in statistical analyses. The significance level was set at p < 0.05.

Results

Type C was more frequent in the second premolar region and the crest type had changed to type U in the second molar region. The predictability of the type U was highest in the second molar region. Moderate agreement was found in the predictability of type U in the molars (κ = 0.602). The mean value of bucco-lingual angulation was highest in the second molar region, followed by the first molar region. There were statistically significant differences between the bucco-lingual angulation of the crest types in the second premolar and first molar regions (p < 0.05).

Conclusions

Bucco-lingual angulation values and morphology change through the posterior mandible. Type U was predicted at a higher rate in the second molar region from panoramic radiographs. These results demonstrate predicting high-risk areas in the posterior mandible for implant therapy from panoramic radiography.

     

Double mandibular foramen leading to the accessory canal on the mandibular ramus

Purpose

The knowledge of the variation in the mandibular foramen and canal is clinically significant in surgical procedures of the mandible. This study aims to evaluate the anatomical characteristics of double mandibular foramen leading to the accessory canal on the mandibular ramus using cone beam CT.

Methods

The sagittal, cross-sectional, and three-dimensional images of cone beam CT data from 446 patients were evaluated in the presence of double mandibular foramen and the accessory canal passing through the foramen. The accessory canals were classified into two types according to the configuration (forward and retromolar type), and the location of double mandibular foramen was recorded.

Results

The eight double mandibular foramina leading to the accessory canals were observed in six patients out of 446 patients (1.35 % of population). Regarding the configuration of the accessory canal, there were two forward types and six retromolar types. All double mandibular foramina were located above the mandibular foramina on the medial aspect of the mandibular ramus.

Conclusion

Three-dimensional images of cone beam CT data are useful in confirming the presence of double mandibular foramen leading to the accessory canal. The variation may cause failure in the routine mandibular nerve block anesthesia and it is often vulnerable during surgical procedures involving the mandibular ramus. Also, double mandibular foramen is considered as an easy route for tumor cell to spread following the radiotherapy. Therefore, the variation should be carefully investigated using reconstructed cone beam CT images in planning of dental surgery or radiotherapy in the mandible.     

300个下颌第一恒磨牙根管类型的透明牙观测

目的 了解下颌第一恒磨牙根管的类型，为提高根管预备的效果提供解剖学依据。方法 采用透明牙技术用连续变倍体视显微镜对该牙根管类型进行观测。结果 300个离体牙中，共检出八种根管类型。其中1—1—1型、2—2—1型、2—2—2型最多，占91．4％。远中舌根的发生率为24．7％；双根管口率：近中根为78．3％，远中根(不含远中舌根，下同)为19．3％；双根管率：近中根为88．3％，远中根为23．3％；双根尖孔率：近中根为56．7％，远中根8．3％，单根管口而有双根尖孔，近中为6．7％，远中为3．3％。结论 下颌第一恒磨牙根管的类型复杂，充分了解其根管解剖对提高根管预备效果、减少根臂遗漏有重要意义。     

Temperature changes on the root surfaces of mandibular incisors after an 810-nm high-intensity intracanal diode laser irradiation

Temperature changes caused by laser irradiation can promote damage to the surrounding dental tissues. In this study, we evaluated the temperature changes of recently extracted human mandibular incisors during intracanal irradiation with an 810-nm diode laser at different settings. Fifty mandibular incisors were enlarged up to an apical size of ISO No. 40 file. After the final rinse with 17% ethylenediaminetetraacetic acid, 0.2% lauryl sodium sulfate biologic detergent, and sterile water, samples were irradiated with circular movements from apex to crown through five different settings of output power (1.5, 2.0, 2.5, 3.0, and 3.5 W) in continuous mode. The temperature changes were measured on both sides of the apical and middle root thirds using two thermopar devices. A temperature increase of 7 °C was considered acceptable as a safe threshold when applying the diode laser. RESULTS: The results showed that only 3.5-W output power increased the outer surface temperature above the critical value. CONCLUSION: The recommended output power can be stipulated as equal to or less than 3 W to avoid overheating during diode laser irradiation on thin dentin walls.     

Uncommon trajectory variations of the mandibular canal and of the mandibular incisive canal: case report

Purpose

This paper aims to report and discuss a case in which unusual anatomical variations were observed in the mandibular canal (MC) and the mandibular incisive canal (MIC) in a same patient.

Materials and methods

A 49-year-old healthy female was referred for mandibular dental implant placement. Panoramic radiography and cone beam computed tomography (CBCT) were performed. Cross-sections, axial, coronal, panoramic reconstructions and volume rendering were obtained.

Results

The panoramic radiograph did not show any evidence of abnormality. CBCT showed a bifid MC on the right side. It extended to the buccal cortex, exteriorized for 6 mm and returned to its conventional trajectory to reach the mental foramen. On the left side, the MIC initially followed its normal trajectory for 4 mm but, in the canine region, it also extended to the buccal cortex and exteriorized.

Conclusion

The advent of CBCT in Dentistry allowed a greater accuracy in the diagnosis of anatomical variations in the jaws, preventing injury to the neurovascular bundle and enabling an adequate surgical planning in the region.     

下颌神经管的解剖结构

背景:在下颌后牙种植术中,由于下颌神经管走行于下颌骨体内,有时可损伤下齿槽神经,因而制约了牙种植术的应用。 因此,牙种植术的应用需详细了解下颌神经管的解剖结构。 目的：观察下颌神经管在下颌骨内的走行及管内的解剖结构。 方法：共纳入15具成人牙下颌骨标本与4具新鲜下颌骨动脉灌注标本。纳入对象均牙列完整,后牙无缺失,牙槽骨无吸收。测量15具成人牙下颌骨标本下颌管走行及其管腔各径长度,包括下颌管横径与纵径,下颌管至上下内外缘距离。观察4具新鲜下颌骨动脉灌注标本管内下颌神经管内神经、血管位置关系。 结果与结论：下颌管内缘至舌侧骨板的距离比下颌管外缘至颊侧骨板距离短(P < 0.01);下颌管上缘至牙槽嵴顶的距离较下颌管下缘至下颌骨下缘的距离大(P < 0.01)。表明下颌管在下颌骨体部走行中偏舌侧、偏下颌骨下缘。下颌神经管在下颌骨体部的部分横径小于纵径(P < 0.05),亦即下颌管截面形态为上下径略长的椭圆形。神经管横纵径于前后牙位区差异无显著性意义。实验还发现在暴露的下颌管腔中下牙槽神经及伴随血管有一层被膜包绕成神经血管束,血管位于神经上方,而且位置恒定,并发出小分支包绕神经。结果提示,下牙槽血管神经束在下颌管内走行中血管位于神经之上。     

下颌第一前磨牙根管系统和根尖孔解剖及临床意义

采用牙髓透明法对 347颗下颌第一前磨牙根管系统的数目和形态进行观察。下颌第一前磨牙根管可分为Ⅰ、Ⅱ、Ⅲ、Ⅳ型。其中Ⅰ型 (单根单管型 )占 83 86 % ,Ⅱ型 (单根双管型 )占 4 6 1% ,Ⅲ型 (单双管混合型 )占 11 2 4 % ,Ⅳ型 (双根双管型 )占 0 2 9%。应用XTT— 3A连续变倍体视显微镜对 347颗下颌第一前磨牙的根管系统形态进行观察 ,根尖分歧出现率 15 6 3% ,根尖分叉出现率 2 4 3% ,根管侧支出现率 1 0 8%。并对 347颗下颌第一前磨牙的根尖孔与根尖顶的位置关系进行观察 ,根尖孔位于根尖顶者占 88 14 % ,位于旁侧者占 11 86 %。并就上述内容的临床意义进行了讨论。     

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。     

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。     

The mandibular canal of the edentulous jaw.

The morphology of the mandibular canal after loss of teeth has received little detailed attention. Improved documentation of this topic would allow better interpretation of dental radiographs and would enable those engaged in tooth implantation to better understand the nature of the tissue into which the prostheses are placed. In this study on mandibles from seven dissecting room cadavers panoramic radiographs usually showed the mandibular canal clearly, an incisive canal less so. The wall of the mandibular canal was similar in dentate and edentulous mandibles, and was highly perforated, as suggested by Cryer (Anderson et al., 1991). In edentulous specimens, it was composed mainly of cancellous bone with only occasional single osteons. The inferior alveolar nerve near the mandibular foramen was a large trunk, consisting of three to four nerve bundles with connective tissue sheaths. It became more loosely arranged toward the mental foramen. Medial to the mental foramen, the nerves were frequently in the form of small bundles in the marrow. Any incisive canal was ill-defined and neurovascular bundles, when present, ran through a labyrinth of intertrabecular spaces.     

下颌管与下颌后牙的位置关系及临床意义

目的: 为下颌牙种植术等临床口腔外科提供解剖学基础。方法：选取新鲜下颌骨标本10例、成人全牙下颌骨标本18例和20名全牙志愿者,分别暴露出下牙槽神经血管束、下颌管与下颌后牙牙根和CT连续扫描后进行三维重建。观察下牙槽神经、血管的排列关系,用游标卡尺和CT三维重建工作站分别测量下颌后牙牙根至下颌管上壁的距离。结果：下颌管自牙槽窝下方走行,其舌侧骨板较厚;下颌管内的下牙槽血管位于下牙槽神经上方。下颌磨牙的远中根至下颌管的距离均较近中根近。在标本及影像上的第1前磨牙、第2前磨牙、第1磨牙、第2磨牙、第3磨牙牙根至下颌管上壁的距离分别为(8.36±2.34)　mm和(8.42±2.42)mm、(7.36±2.21)mm和(7.52±2.18)mm、(3.22±1.40)mm和(3.36±1.85)mm、(2.96±1.54)mm和(2.84±1.55)mm、(3.64±1.72)mm和(3.88±1.76)mm。结论：（1）下颌后牙至下颌管的距离以第2磨牙最近,由近及远依次为第2磨牙、第1磨牙、第3磨牙、第2前磨牙和第1前磨牙。（2）对选择适宜长度的牙种植体,避免牙种植体损伤下牙槽神经等具有重要意义。     

Anatomic and radiologic course of the mandibular incisive canal

The purpose of this article was to define the anatomic and radiographic courses of the incisive mandibular canal and discuss its clinical significance. The study group comprised of 46 hemimandibles fixed in formalin. After radiographic examination, the buccal cortical plate of the mandible was removed leaving the bony frame of the incisive bundle intact. The morphology of the bony walls of the canal was evaluated, as having complete, partial, or no cortical walls. The course of the intraosseous pathway of the canal and its diameter in four different locations were recorded. An incisive bundle was anatomically found in all hemimandibles, travelling within a canal with complete (n = 10), partial (n = 27), or no (n = 9) bony cortical borders. The diameter of the canal ranged from 0.48 mm to 2.9 mm. Radiographically, the canal was either well defined (n = 11, 24%), poorly defined (n = 15, 32%), or undetectable (n = 20, 44%). A statistically significant correlation was found between the anatomic structure of the incisive canal bony borders and its radiographic detectability (p = 0.043). No correlation was found between the anatomic and radiological width of the incisive canal diameter. An incisive canal with a large diameter could have an important role in successful osteointegration and prevention of postoperative sensory disturbances. According to the present study, the ability to interpret the incisive canal from conventional radiographs is limited. Therefore, it is recommended to use conventional tomographs or computerised tomographic dental scans for better imaging of the intermental foraminal area.     

Appearance of the mandibular incisive canal on panoramic radiographs

Panoramic radiographs are routinely used in the dental office for various diagnostic purposes. This study aimed to evaluate the visibility of neurovascular structures in the mandibular interforaminal region on such radiographs. Panoramic radiographs were obtained with a Cranex Tome (Soredex) from 545 consecutive patients using a standard exposure and positioning protocol. For visibility scoring of neurovascular structures, a four-point rating scale was used. The mandibular canal and the mental foramen could be observed in the majority of the cases with good visibility. The lingual foramen was visualized in 71% of the cases, with good visibility in 12%. An incisive canal was identified in 15% of the images, with good visibility in only 1%. An anatomical variation to be considered is the anterior looping of the mental nerve (in 11% of images). Panoramic radiographs can be used for visualization of the mental foramen and a potential anterior looping but not for locating the mandibular incisive canal. To verify its existence for preoperative planning purposes, cross-sectional imaging modalities (HR-CT or spiral tomography) should be preferred.     

Use of phage display technology to investigate allergen-antibody interactions

Phage display is an advanced technology that can be used to characterize the interactions of antibody with antigen at the molecular level. It provides valuable data when applied to the investigation of IgE interaction with allergens. The aim of this rostrum article is to provide an explanation of the potential of phage display for increasing the understanding of allergen-IgE interaction, the discovery of diagnostic reagents, and the development of novel therapeutics for the treatment of allergic disease. The significance of initial studies that have applied phage display technology in allergy research will be highlighted. Phage display has been used to clone human IgE to timothy grass pollen allergen Phl p 5, to characterize the epitopes for murine and human antibodies to a birch pollen allergen Bet v 1, and to elucidate the epitopes of a murine mAb to the house dust mite allergen Der p 1. The technology has identified peptides that functionally mimic sites of human IgE constant domains and that were used to raise antiserum for blocking binding of IgE to the FcRI on basophils and subsequent release of histamine. Phage display has also been used to characterize novel peanut and fungal allergens. The method has been used to increase our understanding of the molecular basis of allergen-IgE interactions and to develop clinically relevant reagents with the pharmacologic potential to block the effector phase of allergic reactions. Many advances from these early studies are likely as phage display technology evolves and allergists gain expertise in its research applications. (J Allergy Clin Immunol 2000;105:1085-92.)     

根管口激光活化冲洗消毒在不规则根管治疗中临床疗效研究

目的探讨根管口激光活化冲洗消毒在不规则根管治疗中临床疗效。方法选择2017年1月至2018年1月于深圳大学总医院因慢性根尖周炎进行不规则根管治疗的136例(136颗患牙)患者,其中男性60例,女性76例;年龄20~75岁,平均年龄48.63岁;C1形70例,C2形66例;病程3~18个月,平均病程6.41个月。根据治疗先后顺序,采用随机数字表法分为观察组和对照组,各68例(68颗患牙);观察组采取根管口激光活化冲洗消毒,对照组采取次氯酸钠冲洗法根管清理消毒;在清洗或激光消毒前后采集样本进行体外细菌培养及根管内菌落计数,随访12个月,记录手术后7 d疼痛反应情况,计算手术前及术后3个月根尖区病损牙槽骨密度,比较两组末次随访时的临床疗效。结果两组消毒后菌落计数均较消毒前明显减少(对照组:7.36 CFU/mL±2.47 CFU/mL vs 2.51 CFU/mL±1.02 CFU/mL;观察组:7.41 CFU/mL±2.38 CFU/mL vs 1.73 CFU/mL±0.79 CFU/mL),而消毒后观察组菌落计数少于对照组,细菌培养阳性率低于对照组(7.35%vs 47.06%),差异均有统计学意义(P<0.05);两组术前1 d疼痛程度比较,差异无统计学意义(P>0.05);观察组术后7 d疼痛程度及约诊间痛发生率均明显低于对照组(0级79.41%、Ⅰ级14.71%、Ⅱ级4.41%、Ⅲ级1.47%vs 0级45.59%、Ⅰ级27.94%、Ⅱ级20.59%、Ⅲ级5.88%;7.35%vs 26.47%),差异均有统计学意义(P<0.05);两组术后3个月根尖区病损牙槽骨密度均较术前明显增大(对照组:91.33 mg/mm^2±2.50 mg/mm^2 vs 80.39 mg/mm^2±5.81 mg/mm^2;观察组:96.94±1.85 mg/mm^2 vs 81.61±5.33 mg/mm^2),组间比较,差异有统计学意义(P<0.05);观察组末次随访时治疗成功率为97.01%,明显高于对照组(87.10%),差异有统计学意义(P<0.05)。结论在不规则根管治疗中应用根管口激光活化冲洗消毒的灭菌效果显著,能有效降低术后短期疼痛程度,提高治疗成功率,不失为一种更有效、安全的消毒模式,具有良好的临床应用前景。     

下颌管的三维重建及临床意义

目的　为下颌牙种植术等临床口腔外科提供解剖学基础。 方法　选取全牙志愿者20名,在螺旋CT机以眶耳线(OML)为基线连续扫描,采用ADW 4.2重建软件的曲面重组技术(CPR)重建下颌管,观察下颌管的位置、构造和测量下颌后牙牙根至下颌管上壁的距离;在Amira三维重建软件下重建下颌骨及下颌管的可视化模型,观察透明下颌骨内下颌管的走行及其与下颌后牙的关系。 结果　下颌管壁由一薄层骨密质构成,自磨牙牙根尖舌侧和前磨牙牙根尖颊侧的下方走行;透明下颌骨内的下颌管可清晰显示其位置、形态及走行,下颌管与下颌体下缘、牙槽嵴及内、外侧骨板的距离。下颌后牙牙根至下颌管的距离以第2磨牙最近,由近及远依次为第2磨牙、第1磨牙、第3磨牙、第2前磨牙和第1前磨牙;下颌磨牙的远中根至下颌管的距离均较近中根近。第1前磨牙、第2前磨牙、第1磨牙、第2磨牙、第3磨牙牙根至下颌管上壁的最短距离分别为(8.38±1.04) mm(左)和(8.44±1.05) mm(右)、(7.51±0.85) mm、(3.40±　0.65) mm、(2.93±0.61) mm、(3.92±0.63) mm(左)和(3.97±0.63) mm(右)。 结论　下颌管的三维重建对选择适宜长度的牙种植体,避免牙种植体损伤下牙槽神经等具有重要意义。     

X-ray microtomographic study of mineral distribution in enamel of mandibular rat incisors

X-ray microtomography was used to study the mineral concentrations in sequential slices of enamel of 5 mandibular incisors which showed an increase from ∼ 1.0 to ∼ 2.7 g cm⁻³ from the apex towards the incisal end. For points at the same distance from the apex, there were differences up to 0.6 g cm⁻³ between the teeth. The change of mean concentrations in the slices with distance could be modelled as (different) saturating exponentials. Under the assumption of a uniform growth rate of a mandibular incisor of 0.6 mm per day and a common time origin for the start of maturation (taken as a mineral concentration of 1 g cm⁻³), the distances were transformed to a common time frame to give a pooled data set. A single saturating exponential could be fitted to this pooled transformed data; this was: C _m = 2.84−1.94exp (−0.18 d ) where Cm is the mean mineral concentration (g cm⁻³) and d the time (days) from the start of maturation. This gives an asymptotic concentration of 2.84 g cm⁻³ towards the incisal end, with a time constant of 7.7 days. The mineral concentration distribution functions were found to be more positively skewed closer to the apex, but more negatively skewed towards the incisal end. The difference between the higher mineral concentration in the outer enamel and the enamel near the amelodentinal junction (ADJ) was ∼ 3%. The direction of maximum increase in concentration from the outer enamel surface to the ADJ meets the boundary of the ADJ at ∼ 80°. Three dimensional surface rendering of isodensity contours showed that the previously described C-shaped pattern of mineralisation is not solely a surface phenomenon, but extends through the depth of the enamel.