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。     

牙支持式数字化导板在牙种植中的临床应用效果

目的 :评估使用牙支持式数字化外科导板引导进行上颌、下颌、前牙、后牙区种植的精准度。方法 :术前经过锥形束CT(CBCT)获得缺牙区颌骨数据信息,扫描上下颌石膏模型获得颌骨数字化模型。采用种植设计软件完成导板的设计,通过快速成型技术完成种植手术导板的制作。在导板引导下完成种植手术。术后拍摄CBCT,将该CBCT数据导入种植设计软件,与术前种植设计数据进行整合后测量种植体位置与术后实际位置的差异。结果:上颌、下颌、前牙、后牙区1～2颗牙缺失患者共29例,植入种植体共45枚。与种植体术前设计植入位置比较,种植体实际植入位置颈部的平均差距为(0.235±0.208)mm;尖端的平均差距(0.55±0.183) mm,深度的平均差距为(0.59±0.070) mm,角度平均差距为(2.48±0.378)°。其中,前牙的植入误差大于后牙。长度超过10 mm的种植体的位置偏差显著高于长度小于10 mm的植体。即刻种植与延期种植无显著差异。结论:牙支持式数字化外科导板引导下的种植具备良好的精准度,特别适合应用于即刻种植。同时在增加种植体的长度时应特别注意控制导板的精准度。     

种植区牙槽骨密度的螺旋CT测量研究

目的：探讨螺旋CT对种植区牙槽骨密度测量的意义。方法：通过对30例上下颌种植区牙槽骨的螺旋CT扫描,在计算机工作站上三维重建、模拟种植,分别测量模拟种植体颈部、中部和根尖部牙槽骨的HU（hounsfield Unites）值,同时测量模拟种植体周围起支持作用的环状区域牙槽骨的HU值,并根据Lekholm和Zarb的分类法确定相对应区域的牙槽骨骨密度分类。结果：所有模拟种植体周围环状区域牙槽骨的平均骨密度为789±235HU,高于模拟种植体区牙槽骨的平均骨密度695±216HU（P〈0.01）,其中,下前牙环状区域牙槽骨平均骨密度最大,为1004±150HU,下颌后牙区为874±241HU,上颌前牙区为821±207HU,上颌后牙区为503±193HU。结论：螺旋CT扫描三维重建,测量模拟种植体周围起支持作用的环状区域牙槽骨密度,对种植前的评估和设计有着重要的指导意义。     

应用螺旋CT及Simplant软件测量种植区颌骨骨密度

目的:应用螺旋CT结合Simplant专业软件对颌骨种植区骨密度进行定量测量,结合Lekholm和Zarb分类法对种植区骨进行分类.方法:对53例拟种植患者进行上下颌骨螺旋CT扫描.扫描图像应用Simplant专业软件进行重建,对136个种植位点的骨密度进行测量,骨密度以Hounsfield units(HU)表示.采用SPSS11.0软件包对数据进行统计学分析,以Mann-Whitney U检验比较不同区域骨密度的差异,并结合Lekholm和Zarb分类法进行分类.结果:所有种植位点的平均骨密度为(714.66±273.72)HU,下颌前牙区的平均骨密度值最大,为(962.96±92.21)HU.其次为上颌前牙区(786.15±188.74)HU、下颌后牙区(785.79±290.91)HU,上颌后牙区骨密度值最小,为(569.67±244.34)HU.所有种植位点中,Ⅳ类骨占26.5%,下前牙区Ⅳ类骨最少,上颌后牙区Ⅳ类骨最多(P＜0.01).结论:下颌前牙区平均骨密度值最大,上颌后牙区平均骨密度值最小.大多数种植位点骨密度分类为Ⅰ类骨和Ⅱ/Ⅲ类骨.Ⅳ类骨所占比例较小.螺旋CT可以提供种植区骨密度的信息,对种植的术前设计和术后评估有重要意义.     

两例外胚层发育不良儿童骨内植入种植体后牙槽骨生长情况

病例一 一外胚层发育不良的患者有严重的下颌骨骨质疏松,先天性缺牙、咀嚼功能丧失。外胚层发育不良表现为头发稀疏、面部畸形、部分缺牙。患者于11岁时在下颌骨前牙区进行5颗Branemark种植体的种植术。愈合后制作种植体支持的固定桥和外托牙。术后1年发现前牙区下颌骨种植体周围和后牙区下颌骨远离种植体区域有显著的牙槽骨生长。术后第二年牙槽骨迅速生长,17岁时患者获得了一定的牙槽骨和下颌高度。     

数字化根尖片作为种植术前骨密度检测方法的评价研究

目的：评估利用数字化根尖片作为种植术前骨质测量手段的准确性和可靠性.方法：利用根尖片术前测量上下颌、前后区共257例种植牙位的植体颈部、中部、根尖部骨密度值,对比术中术者评估的Lekholm和Zarb颌骨分类及植入扭距值,分析其相关性.结果：下颌后牙骨密度93±12高于上颌前牙、上颌后牙及下颌前牙83±28、80±23,81±14（P＜0.05）,后三者间差异无统计学意义.四类骨平均骨密度值（63±5）显明低于其它三类（93±32,90±21,85±24）（P＜0.05）.除颈部骨密度值与植入扭距中度相关外（r=0.6734,P=0.0325）,骨密度与骨分类、植入扭距间无明显相关.结论：数字化根尖片量化评估种植区骨质量精度不足、敏感度差.     

牙槽嵴扩张技术在上颌牙种植中的临床应用

目的　评价牙槽嵴扩张技术在上颌牙种植中的应用效果。方法　对49例牙槽嵴骨量不足的上颌牙种植采用骨扩张器Condenser进行牙槽嵴扩张。根椐不同的缺牙位置,植入与天然牙根直径相当的种植体,以满足患者功能与美学的需要。结果　在49例患者牙槽嵴骨量不足的缺牙区,植入了86枚种植体。术前患者上颌前牙区牙槽嵴宽度平均为3~5·1 mm,术后牙槽嵴宽度平均增加3·3~5·4 mm;术前上颌后牙区,牙槽骨高度平均为6~ 10 mm,术后牙槽骨高度平均增加2~7 mm;种植体均获得初始稳定性;术后6月,X线片显示种植体与牙槽骨形成了紧密的骨性结合骨,种植体植入6个月后进行2期修复。结论　ERE技术适用于上颌牙槽骨扩张,可达到功能与美学的要求,方法简单,值得临床推广。     

牙种植区骨密度的CBCT评价

目的:应用锥形束CT(cone beam computer tomography,CBCT)及Simplant软件,对拟种植的颌骨区骨密度定量测量,参考Lekholm和Zarb分类法对其进行分类,得出一种客观定量的颌骨质量分类方法。方法:通过CBCT对109例拟种植患者的上下颌骨扫描重建,应用Simplant软件对195个种植区骨密度进行测量,骨密度以Hounsfield units(HU)表示。采用SPSS19.0软件以Mann—Whitney U检验进行统计学分析,比较不同区域的骨密度差异。结果:所有拟种植位点平均骨密度为(369.15±181.60)HU。骨密度比较:下颌前牙区[(699.41±138.76)HU]>上颌前牙区[(463.96±145.93)HU]>下颌后牙区[(400.66±123.32)HU]>上颌后牙区[(236.19±150.85)HU]。各类骨的密度参考值:Ⅳ类骨(D4)为<200HU,Ⅱ/Ⅲ类骨(D2/3)为200⁶00HU,Ⅰ类骨(D1)为>600HU。结论:下颌前牙区平均骨密度值最大,上颌后牙区平均骨密度值最小。据此得出一种客观的定量骨分类方法,对种植术前评估有重要意义。     

部分牙缺失种植即刻功能负荷的临床探讨

目的:对部分牙缺失种植即刻功能负荷进行临床探讨。方法:将NobelBiocare种植体植入颌骨内,种植体植入扭力必须达到35Ncm以上。选择永久基台接在种植体上,用一定的扭力拧紧基台,基台水平印模,按常规制作和即刻戴上临时塑料修复体。6周后再印模,制作和戴上烤瓷修复体。结果:36例65枚种植体中,下颌22例41枚种植体,上颌14例24枚种植体,修复后成功率为98.5%。结论:部分牙缺失种植即刻功能负荷初步临床结果是满意的,其长期效果有待进一步的观察。     

应用不翻瓣技术进行后牙区种植义齿修复的临床体会

目的：总结应用不翻瓣技术进行后牙种植义齿修复的临床体会。方法：后牙缺失需要进行种植义齿修复患者53例,男26例,女27例,平均年龄47.4±12.3岁,90颗缺牙。术前均进行CT扫描,三维重建分析缺牙区可用骨长度、宽度和高度,术中环形切除缺牙区黏骨膜进行不翻瓣种植体植入手术,必要时辅助手术导板引导种植体窝洞预备和种植体植入。记录手术耗时时间,术后即刻CT检查植入位置,观察有无并发症的发生,种植体骨结合后完成上部结构修复并定期随访。结果：53例患者应用不翻瓣种植手术成功植入90枚种植体,种植体植入位置良好,术中耗时平均（17.4±5.8）min,无上颌窦底黏膜穿孔、下颌神经损伤、骨壁侧穿等手术并发症,86枚种植体成功修复义齿并经3～10个月随访正常。结论：绝大多数后牙缺牙患者都适合进行不翻瓣种植手术,选择比种植体直径稍大的黏骨膜环切钻更有利于手术,种植体上方皮质骨需要修整后方能使愈合基台准确就位。     

后牙区骨密度对种植体骨结合稳定性的影响

目的应用锥束CT三维重建影像技术对后牙种植区骨密度进行定量测量,同时结合OS—STEL种植体稳定系数（ISQ）,分析表示骨密度的豪森菲尔德单位（HU）值及种植体稳定系数（ISQ）值对植入种植体稳定性的影响。方法对32名（男14人,女18人）后牙种植修复患者的49枚种植体进行术前测量种受植部位HU值,记录植入最大扭矩（Ncm）,在种植初期及5个月后进行共振频率分析（RFA）。结果49枚后牙区种植体全部存留;植入区HU值：477．76±129．88;植入时最大扭矩：35．82±10．275;初期ISQ：77．55±6．84;骨结合后ISQ：78．78±6．25。植人最大扭矩与初期ISQ（P=0．851）、植入区HU值与初期ISQ（P=0．721）未检出相关性,而植入区HU值与骨结合后ISQ值则有显著相关性（P〈0．01）。结论骨密度与种植体骨结合后稳定性密切相关,骨密度HU值越高,预后的种植体稳定性越高。     

Peri-implant bone organization under immediate loading state. Circularly polarized light analyses: a minipig study

BACKGROUND: Immediate loading of dental implants is currently one of the most examined topics in implant dentistry. Using screw implants with a microstructured surface and bone-quality-adapted insertion procedures, osseointegration is achieved when implants are initially stable and when splinted with the superstructure. Despite reported success, there is a shortage of information relating to remodeling and peri-implant bone formation with immediately loaded implants. METHODS: Four to six immediately loaded and unloaded dental implants with a microstructured surface were placed in the mandible and the maxilla in seven minipigs. A total of 85 implants were placed. After a 4-month healing period, all implants were retrieved. Histomorphometry was performed using a light microscope in transmitted polarized light connected to a high-resolution video camera interfaced to a monitor and personal computer. This optical system was associated with a digitizing pad and a histomorphometry software package with image capturing capabilities. RESULTS: Implants showed osseointegration if the average insertion torque of the implants within one bridge was >35 Ncm. If the primary stability of the bridge was <35 Ncm, all implants in the quadrant were lost after 4 months. The multivariate discriminant analysis showed the highest correlation for implant stability by bridge insertion torque (BIT), localization (mandible or maxilla), and implant insertion torque (IIT) as success parameters. The loaded implants displayed collagen fibers, which were oriented in a more transverse way. In addition, a higher quantity of secondary osteons was present. In comparison, the unloaded implants had collagen fibers with a more parallel orientation, and a higher quantity of marrow spaces was present. CONCLUSIONS: When observed after 4 months, immediately loaded implants showed a higher degree of bone formation and remodeling in comparison to unloaded implants. Immediately loaded implants also demonstrated a prevalence of transversely oriented collagen fibers in the peri-implant bone. In this animal model, an average insertion torque of the implants within one bridge>35 Ncm was associated with the most successful implants.     

Implant stability and histomorphometry: a correlation study in human cadavers using stepped cylinder implants

The aim of the present study was to determine the correlation between the primary stability of dental implants placed in edentulous maxillae and mandibles, the bone mineral density and different histomorphometric parameters. After assessing the bone mineral density of the implant sites by computed tomography, 48 stepped cylinder screw implants were installed in four unfixed human maxillae and mandibles of recently deceased people who had bequeathed their bodies to the Anatomic Institute I of the University of Erlangen-Nuremberg for medical-scientific research. Peak insertion torque, Periotest values and resonance frequency analysis were assessed. Subsequently, histologic specimens were prepared, and bone-to-implant contact, the trabecular bone pattern factor (TBPf), the density of trabecular bone (BV/TV) and the height of the cortical passage of the implants were determined. The correlation between the different parameters was calculated statistically. The mean resonance frequency analysis values (maxilla 6130.4+/-363.2 Hz, mandible 6424.5+/-236.2 Hz) did not correlate with the Periotest measurements (maxilla 13.1+/-7.2, mandible -7.9+/-2.1) and peak insertion torque values (maxilla 23.8+/-2.2 N cm, mandible 45.0+/-7.9 N cm) (P=0.280 and 0.193, respectively). Again, no correlations could be found between the resonance frequency analysis, the bone mineral density (maxilla 259.2+/-124.8 mg/cm(3), mandible 349.8+/-113.3 mg/cm3), BV/TV (maxilla 19.7+/-8.8%, mandible 34.3+/-6.0%) and the TBPf (maxilla 2.39+/-1.46 mm-1, mandible -0.84+/-3.27 mm-1) (P=0.140 and 0.602, respectively). However, the resonance frequency analysis values did correlate with bone-to-implant contact of the oral aspect of the specimens (maxilla 12.6+/-6.0%, mandible 35.1+/-5.1%) and with the height of the crestal cortical bone penetrated by the implants in the oral aspect of the implant sites (maxilla 2.1+/-0.7 mm, mandible 5.1+/-3.7 mm) (P=0.024 and 0.002, respectively). The Periotest values showed a correlation with the height of the crestal cortical bone penetrated by the implants in the buccal aspect of the implant sites (maxilla 2.5+/-1.2 mm, mandible 5.4+/-1.2 mm) (P=0.015). The resonance frequency analysis revealed more correlations to the histomorphometric parameters than the Periotest measurements. However, it seems that the noninvasive determination of implant stability has to be improved in order to give a more comprehensive prediction of the bone characteristics of the implant site.     

Biomechanical aspects of primary implant stability: a human cadaver study

Background: The quality of bone is an important factor in the successful implant treatment, and it is evident that higher implant failure is more likely in poor quality of bone. The primary stability of oral implants related to resistance to micromotion during healing is influenced by bone quality, surgical technique, and implant design.
Purposes: The aims of this biomechanical study were to explore the effect of bone quality on initial intraosseous stability of implants, and to determine the correlations between the bone quality and implant stability parameters.
Materials and Methods: Twenty-four implants (Neoss Ltd., Mölnlycke, Sweden) were placed into anterior and posterior regions of three human cadaver mandibles. The bone densities of implant recipient sites were preoperatively determined using computerized tomography (CT) in Hounsfield unit (HU). The maximum insertion torque values were recorded, and primary implant stability measurements were noninvasively performed by means of resonance frequency analysis (RFA).
Results: The bone density values ranged from −267 HU to 553 HU. It was found that mean bone density, insertion torque, and RFA values were 113 ± 270 HU, 41.9 ± 5 Ncm, and 70 ± 7 implant stability quotient (ISQ), respectively. Statistically significant correlations were found between bone density and insertion torque values ( r  = 0.690, p  < .001); bone density and ISQ values ( r  = 0.557, p  < .05); and insertion torque and ISQ values ( r  = 0.853, p  < .001).
Conclusion: CT is a useful tool to assess bone quantity and quality in implant recipient sites, and bone density has a prevailing effect on implant stability at placement.     

Two alternative surgical techniques for enhancing primary implant stability in the posterior maxilla: a clinical study including bone density, insertion torque, and resonance frequency analysis data

Background: The primary stability of dental implants associated with resistance to micromotion during healing is affected by surgical technique and implant design, which are important especially in the soft bone, where implant failures are more likely. Purposes: This study was designed to compare the parameters associated with implant insertion using two different methods of enhancing implant primary stability and to identify any relationship between these parameters at implant insertion. Materials and Methods: A total of 60 implants were placed in the maxillary posterior regions of 22 patients. The bone densities at the implant sites were recorded using a computerized tomography machine in Hounsfield unit (HU). The maximum insertion torque data were recorded with the Osseocare™ (Nobel Biocare AB, Göteborg, Sweden) equipment, while resonance frequency analysis (RFA) measurements were taken using an Osstell™ (Integration Diagnostics AB, Göteborg, Sweden) machine at implant surgery. Comparisons including HU, Ncm, and implant stability quotient were made between two control groups (C1 and C2), and corresponding four test groups (T1–T4) using thinner drills to enhance primary implant stability. Results: Two implants were lost, meaning an overall implant survival rate of 96.6% after 3 ± 1 years. When compared to control groups, significantly higher mean maximum insertion torque and RFA values were found for corresponding test groups. In addition, strong correlations were observed between the bone density and insertion torque, and implant stability values at implant placement. Conclusion: The results of this study suggest that using thinner drills for implant placement in the maxillary posterior region where bone quality is poor may improve the primary implant stability, which helps clinicians to obtain higher implant survival rates.     

A randomized controlled clinical trial comparing the effects of three loading protocols on dental implant stability

Purpose: The primary goal of this stratified randomized controlled trial (SRCT) was to compare the stability of dental implants placed under three different loading regimens during the first 16 weeks of healing following implant placement. Implants were loaded immediately, early (6 weeks), or with conventional/delayed timing (12 weeks). Secondary outcomes were to compare marginal bone adaptation for 3 years after placement. Materials and Methods: Single posterior implant sites in the maxilla or mandible were examined. The insertion torque value was the primary determinant of load assignment. Resonance frequency analysis was performed at follow-up appointments for the first 16 weeks (with results provided as implant stability quotients [ISQs]). Marginal bone levels were assessed via radiographs. Results: Forty patients each received a single 4.0-mm diameter dental implant between 2004 and 2007. One implant failure occurred in Lekholm and Zarb type 4 bone with insertion torque value (ITV) of < 8.1 Ncm; the cumulative success rate was 97.5%. All implants, when classified by bone and loading type, increased in stability over time, with a minor reduction of 1.3 ISQ units seen at 4 weeks in the immediate loading group. The mean marginal bone loss over 3 years was 0.22 mm. The mean ITVs at implant placement for bone types 1 and 2 (grouped together), 3, and 4 were 32, 17, and 10, respectively, and were significantly different (P < .05). Conclusions: ITV was a good objective measure of bone type. Using an ITV of 20 Ncm as the determinant for immediate loading and an ITV of 10 Ncm or greater as the determinant for early loading provided long-term success for this implant and led to no negative changes in tissue response. All bone type groups and loading groups showed no reduction in stability during the first 4 months of healing.     

Sensitivity of resonance frequency analysis method to assess implant stability

The aim of this human cadaver study was to determine the correlation between bone quality and implant stability parameters, and the relationship between resonance frequency value and peri-implant bone loss. Thirty-two implants were placed into four human cadaver mandibles. The bone density of the implant recipient site was determined using computerized tomography (CT) in Hounsfield units (HU). The peak insertion torque values were recorded. The resonance frequency (RF) measurements were performed immediately following implant insertion and also after one, two and three turns of the implant in a counterclockwise direction, representing peri-implant bone loss. The mean bone density, insertion torque and RFA values of all implants were 152 +/- 264 HU, 41.7 +/- 6 Ncm and 69.7 +/- 9 ISQ. Statistically significant correlations were found between bone density and insertion torque values, bone density and ISQ values, and insertion torque and ISQ values. A significant influence of the peri-implant bone loss on ISQ value was also observed. The findings from this study illustrate significant correlation between bone density and implant stability parameters, and a linear relationship between peri-implant bone levels and resonance frequency value.