三维锥形束CT在下颌后牙区牙种植术中的应用体会

目的 探讨三维锥形束CT（cone beam computed tomography,CBCT）在下颌后牙区种植治疗中的应用价值。方法 对50例下颌后牙缺失患者采用CBCT 进行种植治疗前后的影像学检查,得到下颌骨多层面轴位、冠状位及矢状位影像,了解拟种植区牙槽骨的高度、宽度、密度、形态及相邻重要解剖结构的位置关系、种植体与周围牙槽骨骨结合情况。结果 CBCT检查显示种植区三维影像,对种植区骨量、骨质进行准确的测量分析,为种植体直径、长度等的选择提供了准确的依据,为50例下颌后牙区种植手术方案制定提供有效的帮助,成功植入种植体67颗。所有病例均无手术后并发症的发生。结论 CBCT可准确评估种植牙术前下颌后牙区的牙槽骨骨量,并可在术后检查中更清晰地反映种植体周围骨质。     

Implagraphy牙颌面锥形束CT与多层螺旋CT的图像质量对比研究

目的：比较牙颌面锥形束CT与多层螺旋CT的图像质量。方法：分别使用牙颌面锥形束CT和多层螺旋CT对实验模体进行扫描，比较两者显示牙、牙周组织、颌面骨解剖结构的差异。结果：牙颌面锥形束CT图像质量，优于多层螺旋CT。结论：牙颌面锥形束CT因其优秀的图像质量，更加适合口腔临床的需要。     

锥形束CT数字化牙颌模型测量的可靠性和准确性评价

目的:研究应用锥形束CT(CBCT)获取数字化牙颌模型测量的可靠性。方法:选择正畸治疗患者的石膏模型40副,采用CBCT扫描石膏牙颌模型,对其进行测量,并与手工测得的结果进行一致性相关系数(concordance correlationcoefficient,CCC)和均数差(mean difference,MD)比较。结果:所有测量项目的CCC在0.847~0.993之间,大部分测量项目的均数差小于0.25mm,但CFF6、PWF5和PWM6的均数差分别为0.34mm、0.63mm和1.49mm。结论:锥形束CT数字化牙颌模型测量的可靠性好,精确度高。牙尖测量的准确性最高,中央窝次之,腭侧龈缘最低点的测量准确性最低。     

口腔种植术前锥形束CT影像评估上颌窦状况

锥形束CT（CBCT）在种植术中具有非常重要的作用,通过CBCT可以了解种植术前术后的情况,判断种植体植入前植入床的基本条件,判断能否进行种植、种植植入方向、方法以及术后评估等。涉及到上颌窦的种植术应常规拍摄CBCT。本文通过临床实例介绍使用CBCT进行种植术前上颌窦分析评估及判断术后可能发生的改变。     

锥形束CT数字化牙颌模型线性测量的可重复性及精确性研究

目的:本研究目的是探讨锥形束CT数字化牙颌模型线性测量的可重复性及精确性。方法:随机选取17名治疗前的正畸患者分别拍摄CBCT及制取印模。4名测量员分别对CBCT数字化牙颌模型和石膏牙颌模型进行36个指标的测定,每位测量员对每一个指标的测量重复10次。以石膏牙颌模型为标准,应用组内相关系数(ICC)及配对t检验评价CBCT数字化牙颌模型测量的可重复性及精确性。结果:CBCT数字化牙颌模型所有测量项目ICC均高于0.75。CBCT数字化牙颌模型与石膏牙颌模型测量项目之间,均数的差范围是-0.42~0.84mm,其中22项测量项目之间,均数的差异有统计学意义。结论:CBCT数字化牙颌模型测量的可重复性与石膏牙颌模型相当,但在本研究所设定的拍摄条件下,CBCT数字化牙颌模型的测量的精确性不如后者。     

下颌正中管的锥形束CT成像研究

目的 通过锥形束CT（CBCT）对下颌正中管（MIC）的三维位置、走向及毗邻关系进行测量,为确保颏孔前区域牙种植手术的安全提供依据。方法 回顾80例患者的双侧下颌骨CBCT影像,对MIC的直径和毗邻关系进行测量分析,包括MIC至下颌下缘、下颌牙根尖、下颌骨颊侧壁和舌侧壁,以及双侧颏孔连线平面的垂直距离。结果 80例患者中,63例（占78.75%）的CBCT影像上可以观测到MIC影像,其管径大小为（1.21±0.29）mm。在垂直方向上,MIC距下颌下缘和下颌牙根尖的距离分别为（7.82±1.86）、（7.24±2.82）mm;在颊舌方向上,MIC距下颌骨颊侧壁和舌侧壁的距离分别为（3.80±1.37）、（4.45±1.34）mm;MIC距双侧颏孔连线平面的垂直距离为（5.62±2.21）mm。结论 CBCT通过多平面重建后,可以清晰显示MIC在下颌骨中的三维空间位置、走向及毗邻关系;利用CBCT 对MIC的位置和走行进行研究是可行的。     

青少年下颌第三磨牙生长发育的锥形束CT研究

目的　基于锥形束CT（cone-beam CT,CBCT）分析随年龄增长下颌第三磨牙生长发育的变化,为临床判断是否需要预防性拔除第三磨牙提供一定参考。方法　选取2015年10月至2017年10月于吉林大学口腔医院就诊的15 ~ 20周岁患者CBCT数字影像资料,采用分层抽样调查法筛选符合纳入标准的患者96例,其中男44例,女52例。共计下颌第三磨牙192颗。运用Invivo 5.4.5软件测量下颌第二磨牙与第三磨牙长轴之间的角度、下颌第二磨牙后间隙以及下颌第三磨牙牙根长度,并对下颌第三磨牙生长情况进行分类。结果　不同性别患者下颌第三磨牙生长类型分布的差异有统计学意义（χ2 = 14.794,P < 0.05）;不同年龄患者下颌第三磨牙生长类型与生长位置分布的差异均有统计学意义（χ2 = 28.269、80.501,均P < 0.05）,其中垂直生长所占比例随年龄增长大致呈增加趋势;不同年龄患者下颌第二磨牙后间隙及下颌第三磨牙牙根长度比较,差异无统计学意义（均P > 0.05）。结论　通过CBCT测量青少年下颌第三磨牙阻生角度等,为临床医生预测下颌第三磨牙生长发育的变化提供参考。     

锥形束CT对牙种植区骨密度测量的应用

目的 :应用锥形束CT对拟种植区域的骨密度进行定量测量分析,探讨其在种植术前的应用价值。方法 :利用牙科锥形束CT机,扫描43例拟种植患者缺牙区,利用examvision软件重建扫描图像,测量53个预种植位点骨密度。利用SPSS19.0软件对数据进行统计分析,并分析不同区域骨密度的差异。结果:下颌前牙区的平均骨密度值最大,为(922.71±182.41)HU;其次为上前牙区(692.37±71.55)HU、下颌后牙区(542.17±197.40)HU;上颌后牙区骨密度值最小,为(323.57±108.92)HU。缺牙区域的骨密度比较,差异有统计学意义(P<0.05)。结论:所有预种植区域中,下前牙区平均骨密度值最大,上颌后牙区平均骨密度值最小。锥形束CT提供了种植区骨质的情况,对术前种植部位选择,植入和手术方案等提供了重要的参考信息。     

锥形束CT对后牙根尖周炎骨病损的评价作用

目的:以锥形束CT(cone-beam computed tomography,CBCT)为标准,评价X线片在诊断后牙根尖周炎骨病损中的作用。方法:收集门诊同时拍摄X线片和CBCT图像的病例80例,共106颗后牙,包括前磨牙和磨牙各53颗,其中健康牙58颗,临床诊断为慢性牙髓炎11颗,诊断为慢性根尖周炎34颗(含8颗根管治疗后的患牙),根管治疗后表现正常的牙3颗。由2名有经验的医师对CBCT图像及X线片进行判读,确定根尖周指数(periapical index,PAI)分级。采用SPSS13.0软件包对所得数据进行χ2检验。结果:分别对106颗疑似患牙的CBCT图像与X线片进行判读,根尖周炎的检出率分别为59.4%和39.6%,差异有显著性(χ2=8.32,P<0.01)。X线片为二维影像,其结构重叠产生伪影,使病变范围界限不清,而CBCT三维图像则对病损范围有明确的显示,有利于疾病的诊断与治疗。另外,X线片不能表现CBCT显示的骨皮质破坏情况。结论:CBCT图像诊断根尖周炎比X线片更有临床价值,可展现X线片无法显示的细节,对疾病的破坏范围和相关结构毗邻显示更清楚,从而准确划分根尖周炎的分级,为临床正确诊断以及科学制定治疗计划提供有效的依据。     

Comparative study of hydroxyapatite and titanium dental implants in dogs

This study compares the clinical performances and histologic response in dogs to a cylindrical implant with a surface consisting of dense hydroxyapatite (HA) and a threaded titanium implant in functionally loaded and unloaded conditions. Implantation was performed in five dogs, which were killed at 2 or 4 months postfunctional condition (4 or 6 months after implantation). Clinical evaluation showed that neither implant demonstrated significant movement, and assessment of gingival inflammation and sulcus depth showed no significant differences between them. After axial sectioning, the titanium implants were easily removed from the bone, whereas the HA-coated implants were adherent to the bone. Histologically, both implants showed osteogenic ingrowth to the surface in functional and nonfunctional conditions. High-magnification scanning electron micrographs of plastic sections showed that a portion of the interface between the HA-coated implant and the bone showed no gap, whereas gaps were observed at all interfaces with the titanium implant. Histomorphometric analysis by light microscopy indicated that there was no significant difference in the percent bone contact length. Clinically, the two implants behaved similarly.     

Smoking as a risk factor for dental implants and implant-related surgery

Cigarette smoking is known to adversely affect wound healing, and thus may jeopardize the success of dental implantation and implant-related oral surgery. The present study is aimed to present the influence of cigarette smoking on the success and survival of dental implantation as well as on the complication and success of implant-related surgery. We conclude that smokers undergoing both implant-related surgical procedures and dental implantation should be encouraged by their dentists, oral and maxillofacial surgeons, or treating physicians to cease smoking, emphasizing that smoking can increase complications and reduce the success rate of these procedures.     

Relationship between the bone density estimated by cone-beam computed tomography and the primary stability of dental implants

Objectives: The aims of this study were to objectively assess bone quality with density values obtained by cone‐beam computed tomography (CBCT) and to determine the correlations between bone density and primary stability of dental implants. Material and methods: Eighteen Straumann implants were inserted into 18 fresh femoral heads of swine. The bone densities of implant recipient sites were preoperatively determined by the density value using CBCT. The maximum insertion torque value of each implant was recorded using a digital torque meter. Resonance frequency, which represented a quantitative unit called the implant stability quotient (ISQ), was measured using an Osstell^® Mentor immediately after the implant placement. Spearman's correlation coefficient was calculated to evaluate the correlations among density values, insertion torques, and ISQs at implant placement. Results: The density values ranged from 98 to 902. The mean density value, insertion torque, and ISQ were 591±226, 13.4±5.2 Ncm, and 67.1±8.1, respectively. Statistically significant correlations were found between the density values and insertion torque (r_s=0.796, P<0.001), density values and ISQ (r_s=0.529, P=0.024), and insertion torque and ISQ (r_s=0.758, P<0.001). Conclusions: The bone quality evaluated by specific CBCT showed a high correlation with the primary stability of the implants. Hence, preoperative density value estimations by CBCT may allow clinicians to predict implant stability. Whether the density values obtained by the CBCT device used in the present study could be applied to other devices requires further elucidation. To cite this article:
Isoda K, Ayukawa Y, Tsukiyama Y, Sogo M, Matsushita Y, Koyano K. Relationship between the bone density estimated by cone‐beam computed tomography and the primary stability of dental implants.
Clin. Oral Impl. Res. 23 , 2012; 832–836
doi: 10.1111/j.1600‐0501.2011.02203.x     

藏族和汉族下颌前磨牙锥形束CT的对比研究

目的:应用锥形束CT测量藏族和汉族下颌前磨牙牙根和根管并做对比分析,为临床诊疗提供参考.方法:收集藏族和汉族患者下颌前磨牙CBCT图像各150例,测量和比较两个民族下颌前磨牙的牙齿长度、根管弯曲度及弯曲位置、根管类型.结果:藏族下颌第一、第二前磨牙的牙齿长度均较汉族长,二者有统计学差异(P＜0.05).藏族下颌第二前磨...     

Comparison of image performance between cone-beam computed tomography for dental use and four-row multidetector helical CT

The authors evaluated the imaging performance of cone-beam computed tomography (CBCT) for dental use using 3DX multi-image micro-CT (Morita Co., Kyoto, Japan) and four-row multi-detector helical computed tomography (MDCT) using an Asteion (Toshiba, Tokyo, Japan). A dried right maxillary bone was cut into eight slices 2 mm thick toward the zygomatico-palate and used as a phantom. Images of the phantom were then taken using 3DX and MDCT. The images of two bone slices were evaluated by five dentists for image quality and reproducibility of cancellous bone, as well as enamel, dentin, pulp cavity, periodontal ligament space, lamina dura and the overall image. Using the MDCT images as the standard, the 3DX images were evaluated with a subjective 5-level scale: 3 for an image equal to the MDCT image, 4 or greater for better, and 2 or lower for worse. The scores for all parameters exceeded 4 points. Maximum mean score was 4.8 for the lamina dura. Statistically significant differences were found for all items (P < 0.01). Our subjective evaluation of imaging performance clarified that 3DX was superior to MDCT. The results of this study suggest that 3DX is useful for imaging in the dental field.     

Reducing metal artifacts between implants in cone-beam CT by adjusting angular position of the subject

Oral Radiology - To reduce inter-implant metal artifacts in cone-beam CT (CBCT) imaging by adjusting angular position of the subject relative to the source–detector plane. Two dental implants...     

The interface between retained roots and dental implants: a histologic study in baboons

BACKGROUND: This study is a derivative of another study evaluating implant efficacy in baboons. In the previous study it was noted that some implants were placed near or into retained root tips. The purpose of this study was to evaluate the effect of the inadvertent placement of root form implants into or near retained root fragments. METHODS: The baboon has severe dilacerations at the apices of the roots, making extraction very difficult; 120 teeth were extracted from 10 baboons. After the sites had healed, root form implants were placed in each of the sites. Sites were either loaded at various time intervals or left unloaded. Block sections were removed and processed for histologic examination. RESULTS: When the specimens were analyzed, it was noted that several implants were placed through retained root fragments, while others were placed through the periodontal ligament of other root fragments. In a few cases, implants were close to, but not in contact with, either the root or the periodontal ligament. These implants functioned as well as the others in the study. Histologically, there was no inflammation at any site. In some sections, the roots were in intimate contact with the implants, while in others, there was a gap between the two. Where the implant was in contact with the periodontal ligament, there was no apparent fibrous encapsulization of the implant. In some areas, it appeared that a calcified material was deposited on the implants. It was not possible to determine whether this material was bone or cementum. CONCLUSION: Unintentional placement of dental implants into retained root fragments did not result in any inflammation and may have produced cementum or cementum-like matrix on the titanium surface adjacent to the periodontal ligament of the retained root tip.     

Comparative study of wide-diameter implants placed after dental extraction and implants positioned in mature bone for molar replacement

OBJECTIVE: The aim of this study was to compare wide-diameter implants placed in mature bone versus implants inserted in postextraction bone. MATERIAL AND METHODS: A retrospective case study was made; the sample was composed of subjects who had had wide implants placed in the molar area between 2003 and 2005. Two groups were formed: implants placed in mature bone and implants in postextraction bone. A protocol was prepared in which patient age, sex, oral hygiene, implant length, type of prosthesis, and antagonist dentition were collected. After 12 months, data relating to the clinical and radiologic conditions of the implants and the success rate (criteria of Buser et al) were recorded. A statistical analysis of the variables was made (t test, Pearson correlation coefficient, analysis of variance, chi-square). RESULTS: The study examined 162 implants placed in 100 patients. Of the 162 implants, 130 were placed in mature bone and 32 in postextraction bone. Four implants placed in mature bone failed in 4 patients (success rate of 96.9%). None of the implants placed in postextraction bone failed. CONCLUSIONS: The placement of wide-diameter implants in recent molar extraction sites has been shown to achieve similar results to implants placed in healed mature bone after 12 months of follow-up, within the limitations of this study.     

Measurement of buccal bone volume of dental implants by means of cone-beam computed tomography

Purpose: The aim of this study was to evaluate the accuracy of cone‐beam computed tomography (CBCT) for measuring the buccal bone volume around dental implants. Materials and methods: Three to six implants were inserted into the anterior maxilla of eight skulls, depending on the availability of bone, and after this, the CBCT was performed. By means of CBCT image, measurements of the bone wall at three points of the implant were obtained, analyzed and compared with those obtained in the plaster skull casting. Results: The results showed that for the three points of the implants, no statistically significant difference in the measurements was obtained from the plaster model and CBCT images. Conclusions: CBCT can be a useful tool for assessing buccal bone volume along the implant. To cite this article:
Shiratori LN, Marotti J, Yamanouchi J, Chilvarquer I, Contin I, Tortamano‐Neto P. Measurement of buccal bone volume of dental implants by means of cone‐beam computed tomography.
Clin. Oral Impl. Res. 23 , 2012; 797–804.
doi: 10.1111/j.1600‐0501.2011.02207.x     

Diabetes mellitus and dental implants: a clinical study

Diabetes mellitus is no longer considered to be a contraindication for implant-supported prostheses, provided that the patient's blood sugar is under control, and that there is motivation for oral hygiene procedures. This paper presents the experiences of treating diabetic patients using implants with good success rates.