可注射性磷酸钙骨水泥修复下颌阻生第三磨牙微创拔除后牙槽骨缺损

目的:研究一种可注射性磷酸钙骨水泥(ICPCS)修复下颌阻生第三磨牙微创拔除后牙槽骨缺损的临床效果。方法:将下颌阻生第三磨牙需拔除,同时X线片显示其近中第二磨牙远中牙槽骨已丧失1/3以上的33例患者分为2组。试验组17例,17颗下颌阻生第三磨牙微创拔除后应用ICPCS注入第二磨牙远中牙槽骨缺损。对照组16例,16颗下颌阻生第三磨牙微创拔除后采取血凝块机化愈合。分别于拔牙术后1周及术后1、3个月复查,比较两组患者术后伤口愈合情况、牙周临床指标及X线片。结果:全部33例患者伤口均顺利愈合,牙周评估指标显示术后1、3个月的ICPCS组下颌第二磨牙牙周状况明显改善。X线片示术后1、3个月下颌第二磨牙远中骨缺损区的骨密度明显增高,远中牙槽嵴高度有明显增高,均位于远中牙根1/3以上。结论:ICPCS具有良好的可注射性、操作方便、组织相容性好、降解时间适当和骨引导骨诱导能力,能修复下颌阻生第三磨牙微创拔除后下颌第二磨牙远中缺损骨壁,明显改善其牙周状况及牙松动。     

Shape of the lingula and its localization by panoramic radiograph versus dry mandibular measurement

BACKGROUND: To evaluate the incidence of lingula shapes in Thai adult mandibles and to compare the accuracy of panoramic radiograph measurement with the dry mandible measurements for localizing the position of the lingula. METHODS: Seventy-two dry adult mandibles (144 sides) from 52 males and 20 females of Thai origin were classified as triangular, truncated, nodular or assimilated. Twenty-three mandibles, composed of both first molar and canine on the same side (33 sides), were selected for distance measurement. The ten distances from the lingula to the anterior, posterior ramus, to the coronoid notch and lower border of the mandible were measured on the dry mandibles and compared with the same distances on panoramic radiographs. The distribution of the lingula shape is described. Paired t test and correlation were used to evaluate the accuracy of panoramic radiographs in localizing the position of the lingula. RESULTS: Truncated lingula were most commonly found (68 sides or 47%). Nodular, triangular and assimilated shapes were found in 33 (23%), 24 (17%) and 19 subjects (13%), respectively. The distance differences between the panoramic radiograph measurement and the dry mandible measurement were statistically significant (P < 0.01). The positive correlations between the panoramic and dry skull measurements were high (0.59-0.91). CONCLUSIONS: The lingula has different shapes in different populations. In adult Thai mandibles, the truncated lingula shape is most common. Panoramic radiographs present not only the position but also the shape and number of lingula and mandibular foramen. There is a high concordance between the measured distances in panoramic radiography and dry mandibles.     

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.     

Iatrogenic mandibular fracture associated with third molar removal

Third molar extraction is one of the most common procedures performed in oral and maxillofacial surgery units. It is sometimes accompanied by complications such as alveolar osteitis, secondary infection, hemorrhage, dysesthesia and, most severely, iatrogenic fracture. This article describes two mandibular angle fractures that occurred in two patients during the surgical extraction of one erupted and one unerupted third molar, including a brief review of the literature.     

Correlation of mandibular impacted tooth and bone morphology determined by cone beam computed topography on a premise of third molar operation

Purpose

To determine the width and morphology of the mandible in the impacted third molar region, and to identify the location of the mandibular canal prior to planning impacted third molar operations.

Methods

Cone beam computed tomography (CBCT) data of 87 mandibular third molars from 62 Japanese patients were analyzed in this study. The width of the lingual cortical bone and apex-canal distance were measured from cross-sectional images in which the cortical bone was thinnest at the lingual side in the third molar region. Images were used for measuring the space (distance between the inner border of the lingual cortical bone and outer surface of the third molar root), apex-canal distance (distance from the root of the third molar tooth to the superior border of the inferior alveolar canal) and the cortical bone (width between the inner and outer borders of the lingual cortical bone).

Results

The means of the space, apex-canal distance and lingual cortical width were 0.31, 1.99, and 0.68 mm, respectively. Impacted third molar teeth (types A–C) were observed at the following frequencies: type A (angular) 37 %; type B (horizontal), 42 %; type C (vertical), 21 %. The morphology of the mandible at the third molar region (types D–F) was observed as: type D (round), 49 %; type E (lingual extended), 18 %; and type F (lingual concave), 32 %.

Conclusions

The width and morphology of the mandible with impacted teeth and the location of the mandibular canal at the third molar region could be clearly determined using cross-sectional CBCT images.     

Timing of human mandibular third molar formation

Background: Population differences in tooth formation using radiographs can be determined if the entire developmental sequence of a single tooth is studied. The only developing tooth visible radiographically from initiation to root completion is the third molar or wisdom tooth.

Aim: The timing of mandibular third molar formation was documented for two groups of children in England and two in South Africa.

Subjects and methods: Panoramic radiographs of White and Bangladeshi children from London and Black African and Cape Coloured children from South Africa were examined (age 5–24). Mean age of entering third molar stages (crypt appearance to root completion) was calculated using logistic regression and compared between sex and group using a t-test.

Results: Average age of third molar stages was significantly (p?<?0.001) later in three groups for almost all stages of the third molar compared to Black children. The average age of entering initial mineralization ranged from 7.97 to 9.74 years while average age of apex closed was 19.27–20.88.

Conclusion: These results show for the first time a significant difference in the timing of maturation of the mandibular third molar between groups with South African Black children being earlier than other groups.     

临床观摩式护理干预与下颌阻生牙拔除患者的焦虑状况

目的:下颌阻生牙拔除患者通常存在围手术期的焦虑症状,本研究探讨临床观摩式的护理干预对门诊拔除阻生牙患者焦虑情况的影响。方法:238例患者随机分为实验组和对照组,两组患者均接受常规的健康宣教和临床资料收集。实验组采用临床观摩式护理干预,患者观摩临床阻生牙拔除的全过程。两组于手术前、后行HAMA量表检测患者的焦虑状况。结果:实验组和对照组术后的HAMA值有显著性差异(P<0.05),而术前无统计学意义。结论:临床观摩式的护理干预有助于下颌阻生牙拔除患者降低患者的焦虑状况。     

舌神经在下颌第三磨牙区的毗邻关系及其临床意义

本文在53侧成人头部标本上对舌神经在下颌第三磨牙区的毗邻关系进行了研究。舌神经在第三磨牙后区多为扁圆形,在第三磨牙舌侧多为扁平形,平均横径为1.7mm,舌神经距第三磨牙槽嵴的垂直距离为11.2mm、距第三磨牙远中距离为9.0mm、距牙槽骨舌侧骨板的水平距离为3.0mm、距下颌舌骨肌附着缘的距离为6.2mm。对拔除第三磨牙时,损伤舌神经的解剖学原因进行了探讨并提出防止其损伤的建议。     

Mandibular radiomorphometric measurements as indicators of possible osteoporosis in postmenopausal women

OBJECTIVE: The use of mandibular anatomic indicators on panoramic radiographs, i.e. the number of lost teeth, mandibular cortical width at the mental region (MCW), panoramic mandibular index (PMI), alveolar crest resorption degree (M/M ratio) and morphologic classification of the mandibular inferior cortex (MIC grade) can be useful in the evaluation of bone resorption in different age groups of women to determine the presence of osteoporosis. The purpose of this study was to assess the validity of mandibular radiomorphometric measurements and to determine the frequency of tooth loss in postmenopausal women. SUBJECTS AND METHODS: An assessment of the number of lost teeth, MCW, PMI, M/M ratio and MIC grade was performed on dental panoramic radiographs in a group of 133 postmenopausal women 38-80 years-of-age. BMD at the lumbar spine was measured by dual energy X-ray absorptiometry. BMD values were categorized as normal (T-score greater than 1.0), and as indicative of osteopenia (T-score -1.0 to -2.5) or osteoporosis (T-score less than -2.5) according to the World Health Organization classification. RESULTS: In our study when the T-score at the lumbar spine is decreased, the age of menopause is increased, and the MCW is decreased to a point of statistical significance. A decrease in MCW by 1mm increases the likelihood of osteopenia or osteoporosis to 43%, having taken into consideration the effect of the years elapsed since menopause. It was also shown that age, years since menopause, MCW value, and the number of teeth lost have a statistically important effect on the incidence of moderate or severe cortical erosion. Moreover, when the MCI is C2 or C3 (mild or severe erosions) the age is increased, the years since menopause are increased and the MCW is decreased to a point of statistical significance. As far as tooth loss is concerned, an increase by 1 unit in the number of teeth lost, increase the likelihood of moderate or severe erosion to 6%, having taken into account the years elapsed since menopause. Our study also demonstrated that postmenopausal women tend to lose their teeth at an age older than 50 years. They usually lose the 1st and 2nd mandibular molars and the 1st and 2nd maxillary premolars. Loss of front teeth and canines occurs at an age older than 60 years (except for the lateral maxillary incisors). At a younger age they tend to lose the 2nd maxillary premolars more frequently than their mandibular counterparts. CONCLUSIONS: In conclusion, panoramic radiographs constitute an integral part of almost every routine dental evaluation and can be useful for the early diagnosis of osteoporosis in postmenopausal women. Dentists have sufficient clinical and radiographic information that enables them to play a significant role in patient screening for osteoporosis.     

钛植入体过盈装配对下颌骨骨重建影响的数值研究

目的研究下颌骨修复手术钛钉植入后由于过盈装配而产生的下颌骨内应力以及骨密度分布变化,探讨不同过盈量对下颌骨骨重建的影响。方法采用有限元方法,建立8种不同过盈量的钛钉过盈装配模型,利用骨重建理论中的应变能密度算法计算5%、10%、15%、20%、25%、30%、35%、40%过盈量模型在36个月内下颌骨应力和骨密度的变化。结果导向孔直径大于钛钉内径时,随着过盈量的增大,骨-钉界面的固定效果逐渐增强;而过盈量超过30%之后,反而会因为过高的过盈量引起大量骨的失效,造成钛钉固定作用的减弱。结论在下颌骨修复时,建议选择直径大小等于或略小于钛钉内径大小的导向孔。     

下颌骨节段性缺损修复组织工程中珊瑚支架残留率的研究

目的探讨骨髓基质干细胞(bone marrow stromal cell,BMSC)复合珊瑚修复犬下颌骨节段性缺损支架的残留率。方法体外扩增、成骨诱导培养犬BMSC,分别将第二代细胞复合珊瑚后植入犬自体右侧3cm的下颌骨节段性缺损,术后12周(n=6),32周(n=6)取材后分别通过Micro-CT检测和大体、组织学图像分析骨修复、支架残留率和生物力学修复强度。结果 Micro-CT检测和组织学图像分析均表明,BMSC-珊瑚组组织工程骨12周时支架残留率显著高于32周(P0.05),而新骨随材料降解逐步成熟;生物力学显示术后32周力学强度显著高于12周(P0.05)。结论自体成骨诱导BMSC复合珊瑚形成的组织工程骨可良好修复犬下颌骨节段性缺损,随时间延长材料逐步降解,组织工程下颌骨进一步成熟。     

三维有限元分析下颌骨不同部位受力髁突的力学应变

背景：髁突骨折可以发生在直接及间接外力作用下,其危险性与撞击作用部位有着何种相关关系,目前报道较少。 目的：快速建立正常下颌骨的三维有限元模型,采用有限元方法分析下颌骨不同部位受力对髁突力学应变情况。 方法：以颌骨发育正常,无任何口腔疾患的青年志愿者1例进行多层螺旋CT扫描,利用医学逆向工程软件Mimics和大型有限元软件MSC.Patran建立下颌骨三维有限元模型并对下颌骨体部、颏部、下颌角部及髁突等部位进行数值撞击试验,对所建模型进行可行性验证。 结果与结论：①快速建立下颌骨三维有限元生物力学模型,重现了下颌骨的几何外形,能够得到下颌骨髁突的直观整体印象。建立的几何模型包括80 044节点和18 441单元。②于下颌骨颏部、一侧下颌体部、下颌角及髁突处分别加载100 N压力时,骨皮质中最大等效应力出现在髁突区域,髁突发生骨折的危险性最大。实验结果有助于从力学上对于髁状突骨折类型进行分析及对骨折的程度进行判断。 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程     

Distribution of BMP6 in the alveolar bone during mouse mandibular molar eruption

Eruption requires synchrony of the tooth with the surrounding tissues, particularly the bone. One important step during eruption is remodelling of the alveolar bone at the base of the tooth and along the roots. Expression of BMP6 was reported to be increased in the basal half of the dental follicle prior to eruption and inhibition of BMP6 affected bone formation at the base of the alveolar crypt. The aim of this study was to further investigate BMP6 protein in relation to tooth eruption and the corresponding bone remodelling using temporospatial correlations of BMP6 localization with morphogenetic events (proliferation, differentiation, apoptosis and bone apposition/resorption), other BMPs (BMP2 and BMP7) and three-dimensional images of tooth–bone development. BMP6 expression pattern was mapped in the mandibular molar teeth and related structures around eruption. Localization of BMP6 dominated in osteoblasts, in regions of bone formation within the alveolar crypt. These findings positively correlated with proliferation at the tooth base region, osteocalcin expression in the osteoblasts/osteocytes and BMP2 and BMP7 presence in the alveolar bone surrounding the tooth. Osteoclast activity and apoptotic elimination in the root region gradually decreased before eruption and totally ceased at eruption stages. Generally, BMP6 positively correlated with BMP2, BMP7 and osteocalcin-positive osteoblasts, and areas of bone remodelling. Moreover, BMP6 was found in the periodontium and cementoblasts. BMP6 expression in the alveolar bone accompanied tooth eruption. Notably, the expression pattern of BMP6 in the bone did not differ around individual molar teeth at the same stage of development. The expression of BMP6 in periodontal ligaments may contribute to interaction between the tooth and bone during the eruption and anchoring process.     

种植体联合牙半切剩余牙体共同支持下颌磨牙的三维有限元分析

BACKGROUND: Tooth hemisection contributes to preserving partial tooth structure and periodontal ligament that are able to reduce the resorption of alveolar bone. However, the traditional fixed partial denture (FPD) for dental restoration after hemisection jeopardizes the health of abutment tooth. Given this, the use of dental implant offers a new option for tooth restoration. OBJECTIVE: To analyze the feasibility of preserving a mandibular molar after hemisection by combining an inserted dental implant with the residual tooth by means of finite element analysis. METHODS: Based on the image data of a volunteer, three models with different ways of restorations were created: the model of combining implant and residual tooth after hemisection to support a molar crown (combined model), the model of implant to support a molar crown (implant model) and the model of FPD. Densities of two kinds of spongy bones were assigned respectively. Vertical load of 100 N was applied on the prosthesis. Biomechanical properties of different models were analyzed. RESULTS AND CONCLUSION: (1) Displacement of the tooth and implant: As the decrease of the density of spongy bone, displacements of the tooth and implant increased in the combined model. The implant displacement was higher in the combined model as compared with the implant model. For the combined model, the implant displacement was lower than that of the residual tooth. (2) Stress in the cortical bone: Stress in the cortical bone in models with low-density spongy bone was higher than that in the corresponding models with high-density spongy bone. Under the condition of high-density spongy bone, the highest values were obtained in the implant model, followed by the combined model and FPD model. Under the condition of low-density spongy bone, the highest values were obtained in the combined model, followed by the implant model and FPD model. (3) Strain in the spongy bone: Strain in the spongy bone in models with low-density spongy bone was higher than that in the corresponding models with high-density spongy bone. Under the condition of high-density spongy bone, the highest values were obtained in the FPD model, followed by the combined model and implant model. Under the condition of low-density spongy bone, the highest values were obtained in the combined model, followed by the FPD model and implant model. From the biomechanical point of view, it can be concluded that the combined use of an implant and residual molar after tooth hemisection is an acceptable treatment option under the condition of high-density spongy bone.     

钛板重建下颌骨体部缺损的生物力学变化

BACKGROUND:Three-dimensional finite element has been widely used in the oral cavity field, but little is reported on the three-dimensional finite element reconstruction of the mandibular body using titanium plate. OBJECTIVE:To study the biomechanical characteristics of reconstructing the mandibular body using titanium plate. METHODS:We established a three-dimensional finite element model of mandibular body defect undergoing reconstruction using bicortical titanium screws and titanium plate. Under the simulated normal occlusion state, a 200 N vertical load was added to the central fossa of the occlusal surface of the right mandible first molar. Then, stress distribution and maximum displacement of the mandible, titanium screw, and titanium plate were analyzed. RESULTS AND CONCLUSION:Under the simulated normal occlusion state, mandible stress was concentrated in the mandibular body and mandibular branch, especially in the anterior and posterior edges of the mandibular branch and the lower edge of the mandible. The stress in the posterior edge of the mandible was lower than that in the anterior edge of the mandible, and moreover, the contact site between the titanium plate and the mandible also presented a concentration of stress. The maximum stress of the bicortical titanium screws appeared near the screw cap, and the stress was also concentrated at the contact site between the titanium screw and the titanium plate. The maximum stress of the titanium screw at the ascending branch of the mandible was higher than that of the titanium screw at the anterior end of the defect. For the titanium plate, the stress was mainly concentrated at the fixed site of the titanium screws; the peak stress of the anterior and posterior edges of the titanium plate was found at the contact site between the anterior end of mandibular defect and the titanium stress as well as between the ascending branch of the mandible and the titanium screw. After mandibular body reconstruction using the titanium plate, a displacement was likely to occur at the contact site between the anterior end of mandibular defect and the titanium plate. In conclusion, these findings indicate that mandibular body reconstruction using bicortical titanium screws and titanium plate is relatively stable, but the titanium plate fixed at the anterior part of the mandibular angle is prone to breakage.     

The remodeling of alveolar bone supporting the mandibular first molar with different levels of periodontal attachment

The objective of this study was to investigate alveolar bone remodeling of the mandibular first molar with differing levels of periodontal attachment under mastication loading. Three-dimensional finite element models of the mandibular first molar with differing levels of periodontal attachment were established. The stress distributions and bone density changes were analyzed under mastication loading to simulate the remodeling process of mandibular bone based on the theory of strain energy density. The results showed that the alveolar buccal, lingual ridges and root apex areas experienced higher stresses. The stresses and densities of the alveolar bone increased proportionally to increased mastication loading. Decrease in alveolar bone density under extreme loading indicated bone resorption. The remodeling rate was continual with gradual loading. Periodontal ligament support marginally decreased with an increased remodeling rate under extreme loading. Changes in alveolar bone density can reflect the remodeling process of periodontal tissue under mastication loading. The relationship between the change in density and mastication loading during remodeling can provide useful indicators into clinical treatment and diagnosis of the periodontal disease.     

Evaluation of the mandibular third molar pericoronitis flora and its susceptibility to different antibiotics prescribed in france

This work assessed the polymicrobial flora of mandibular third molar pericoronitis. Obligate anaerobes were found in almost all cases (32 of 35). Amoxicillin and pristinamycin were the most effective against the flora, particularly aerobic organisms. Metronidazole alone or combined with spiramycin was the most effective drug against obligate anaerobes.     

骨髓间充质干细胞与同种异体骨复合修复犬下颌骨缺损：成骨能力检测

 背景：同种异体骨与自体骨有相似解剖外形和生物学特性,是较佳的生物支架材料。自体骨髓来源的间充质干细胞具有多分化潜能,能向成骨、成软骨细胞分化,加速骨组织及软骨组织的形成。目的：探讨同种异体骨支架复合自体骨髓间充质干细胞促进犬下颌骨半侧缺损的新骨成骨能力。方法：拔出24只比格犬左侧下颌牙,伤口愈合后2个月,人为造成犬下颌骨缺损,对照组用单纯冻干同种异体骨修复,实验组用同种异体冻干骨加自体骨髓间充质干细胞修复。术后4,12,24周对下颌骨体部进行骨密度扫描以及Micro-CT检查。结果与结论：实验组移植后12周开始,下颌骨的骨密度显著高于对照组(P < 0.05),随着时间推移,实验组和对照组骨密度均增高,但实验组增高明显高于对照组。随时间推移,实验组骨结构参数成阶梯式递增或递减,对照组虽也有递增或递减,但不明显。术后24周实验组感兴趣区骨小梁分离度大于对照组(P < 0.05),骨体积分数、骨小梁数量、骨小梁厚度小于对照组(P < 0.05)。结果表明骨髓间充质干细胞能加速同种异体骨的骨改建速度。中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程全文链接：     

Relationship between accessory foramina and tumour spread in the lateral mandibular surface

The spread of tumour cells to the mandible has been well recognised and invasion of the edentulous alveolar ridge by tumour through accessory foramina has been documented. Tumour infiltration can also occur through the lateral cortical plate, but the number and distribution of accessory foramina on this surface has not been reported. Lateral surfaces of 89 mandibles were examined and accessory foramina which showed a direct communication with the underlying cancellous bone were charted. It was found that the number of accessory foramina varied greatly from specimen to specimen. Only 70.8% of mandibles showed foramina in the coronoid, sigmoid and condylar sections; of these 93.7% exhibited foramina in the condylar section, 23.8% in the coronoid and only 19% in the sigmoid section. This finding confirms that the current practice of conserving part of the ascending ramus posterior to the coronoid process following surgery is sound. Similarly in the rest of the lateral surface, foramina were present in the upper third section in 97.8% of mandibles, 61.8% in the lower third and 58.4% in the middle third sections. This result justifies the principle of rim resection in appropriate cases and the recognition that the alveolar section is commonly invaded before the rest of the body. The number and distribution of foramina may be of greater significance following radiotherapy when the foramina could provide multiple direct channels for invasion of tumour cells from the lateral surface to the medulla.     

Analysis of mandibular variability in humans of different geographic areas

The mandible is the single mobile bone of the skull. It develops from the sixth week of the intrauterine life. The aim of our study is to confirm the variability of different mandibular landmarks in humans of different geographic areas. A number of 100 young persons from different geographic areas (Europe, Middle Orient, Asia and Africa) were selected. We used the classical measurement with the metric band and Baudeloque compass and analysed 50 cephalograms in frontal and lateral views. The focus of our measurements were the opening of the mandibular angle (gonion), ramal length and width, condylar diameters and the gonion–menton distance. In the European specimens, the opening of the mandibular angle is smaller than in the Asians. Africans had a lower value of the mandibular angle than Asians. Significant differences appeared in the gonion–menton distance measurements, as well. In conclusion, there is a positive correlation between the mandibular angle and the menton–gonion distance, respectively.