单个下颌磨牙缺失种植修复的三维有限元分析

目的:分析单个下颌磨牙缺失时不同设计的种植修复的种植体-骨界面的应力分布情况。方法:采用三维有限元法。结果:与单个标准直径种植体修复相比,采用单个大直径种植体或双种植体修复单个缺失下颌磨牙均可使种植体-骨界面应力值大大降低;而采用单个大直径种植体修复单个缺失磨牙时骨界面应力值相对较小,以斜向加载时更为明显。结论:建议临床采用单个大直径种植体或双种植体修复单个缺失下颌磨牙。当颌骨颊舌径足够时,以大直径种植体修复为佳。     

不同直径和数目种植体支持修复下颌第一磨牙的有限元分析

目的分析种植体支持修复下颌第一磨牙时,不同直径和数目种植体对种植体骨界面应力分布的影响。方法建立3种不同直径的单种植体和1种双种植体支持修复下颌第一磨牙的模型,运用三维有限元法,分析种植体骨界面应力分布。结果单种植体设计模型,随直径的增大,种植体及周围骨vonMises应力值减小。双种植体设计模型,种植体及周围骨vonMises应力值小于单种植体。结论双种植体和宽直径单种植体支持修复下颌第一磨牙的设计有利于种植体及周围骨应力的分布。     

不同空间排列双种植体支持修复下颌第一磨牙的力学分析

目的分析双种植体支持修复下颌第一磨牙时,2种植体不同空间排列对种植体骨界面应力分布的影响。方法模拟不同空间排列的双种植体支持修复下颌第一磨牙的模型,在保证其它因素都不变的情况下,采用三维有限元法,分析种植体骨界面应力分布。结果种植体和周围骨应力随两种植体长轴交叉角度增大而逐渐增大,但差异并不显著。结论双种植体支持修复下颌第一磨牙时,2种植体适当内聚(<10°)排列,有利于种植体固位和支持。     

下颌第一磨牙的双根种植修复

下颌第一磨牙的种植修复是临床常见的，传统方法是种植单个种植体修复单个冠。近年来，有研究提出恢复第一磨牙的牙根数目的种植修复方法。本文对双根种植修复下颌第一磨牙的适应症、优缺点，生物牙台力等方面进行综述。     

大直径种植体修复单个磨牙的疗效分析

目的:评价大直径种植体修复缺失单个磨牙的临床效果,并对疗效加以讨论。方法:对187个单个磨牙缺失的患者植入255枚根形、直径为5.5mm或6.5mm的Frialit-2种植体,其中42枚为即刻种植,53枚种植体植入时联合采用了上颌窦提升术。255枚种植体中上颌植入112枚,下颌植入143枚。二期手术在种植3-6个月完成,种植修复完成后6、12、24、36、48个月,分别对种植体进行临床和X光检查,并对种植体的稳定性、种植体颈部骨组织改建的情况、基台螺丝的松动及种植体周围软组织进行检查随访。结果:二期手术时,255枚种植体中除上颌3枚即刻种植体未形成骨整合外,其余种植体均形成了良好的骨结合,种植体成功率98.4%。种植修复12个月后,种植体颈部骨吸收约0.18±0.05mm;48个月颈部骨吸收0.08±0.02mm。3例患者的5枚种植体的基台螺丝松动。结论:大直径种植体具有较标准种植体更接近天然牙解剖特点和符合义齿机械力学原则的优势,对于缺失磨牙的种植修复,大直径种植体可获得较好的远期效果。     

双种植体支持单个磨牙种植义齿的5年临床效果观察

目的：评价双种植体支持单个磨牙种植义齿修复的临床效果：方法：对16例下颌第一磨牙缺失且失牙间隙近远中宽度在12mm或以上的患者，采用两个种植体支持单个磨牙修复：在修复体完成后3个月，1年，5年对种植体周围骨组织吸收状况、种植体和修复体的稳定性及种植体周围组织状况进行了随访。结果：在修复后3个月及1年均没有发现修复体松动；在修复后5年有3例出现修复体松动。没有种植体松动发生。结论：用双种植体支持单个磨牙的种植义齿修复更符合义齿的机械力学原则，具有较高的成功率和良好的修复效果。     

口腔生物力学

穿下颌种植体周围骨界面应力分析;双根管牙及其桩核烤瓷冠三维有限元模型的建立;残冠牙体余量对核桩冠桩根联合体水平承载力学性能的影响;上颌第一磨牙核桩冠的三维有限元模型建立;下颌磨牙游离缺失套筒冠修复的基牙受载分析     

下颌骨形态对种植体-骨界面应力分布影响的研究

目的　模拟单个下颌磨牙缺失的种植修复 ,分析不同下颌骨形态对种植体 骨界面应力分布的影响。方法　采用三维有限元法 ,根据下颌骨测量资料建立不同颌骨截面形态的种植修复模型并进行分析。结果　不论垂直载荷或斜向载荷 ,不同颌骨形态模型骨界面应力分布规律及应力值差异均无显著性。其中Von Mises应力最大差异为 6 4% ,压应力最大差异为 2 8% ,拉应力最大差异为 6 2 %。结论　在有限元研究中将下颌骨形态简化为规则形态是合理的     

双种植体支持单冠修复宽间隙单颗磨牙缺失的临床效果观察

目的观察双种植体支持单冠修复缺牙间隙较大的单磨牙缺失的临床效果。方法患者17例，共缺失18颗磨牙，缺牙间隙近远中宽度大于或等于12mm，采用两颗Xive种植体支持，单冠修复，修复完成后，定期随访，复诊时拍摄全景片，比较修复前后骨量的变化，临床检查种植体、基台和修复体的稳固性及牙龈状况，询问患者使用种植修复的情况。结果18颗磨牙缺失共使用36颗种植体修复，种植修复成功率为100％。17例患者中除1例患者认为外形欠佳外，其余16例全部表示满意，满意度为94．4％。结论双种植体适合间隙较大的单颗磨牙缺失种植修复，临床效果满意。     

动态载荷下双种植体单冠修复下颌磨牙的三维有限元分析

目的探讨动态载荷作用条件下,双种植体单冠修复下颌磨牙的最佳聚合角度。方法分别建立聚合角度为0°、5°、10°、15°双种植体单冠修复下颌磨牙的三维有限元模型,对修复体施加一个周期为0.875 s的动态载荷,分析种植体周围骨组织的应力分布和种植体-基台复合体位移值情况。结果①种植体周围皮质骨最大Von-Mises应力值:5°聚合角度模型>10°聚合角度模型>15°聚合角度模型>0°聚合角度模型;种植体周围松质骨最大Von-Mises应力值:15°聚合角度模型>10°聚合角度模型>5°聚合角度模型>0°聚合角度模型;②种植体-基台复合体最大位移峰值:15°聚合角度模型>5°聚合角度模型>10°聚合角度模型>0°聚合角度模型。结论动态载荷下,双种植体单冠修复下颌磨牙的最佳聚合角度为0°。     

下磨牙区种植体尖端与下颌管间安全距离的探讨

目的:探讨下颌磨牙区植入的种植体尖端与下牙槽神经管上缘之间的安全距离。方法:用游标卡尺测量23例患者全景片中的30颗下颌磨牙区种植体长度,除以对应的种植体实际长度,计算全景片中下颌磨牙区垂直放大率(vertical magnification factor,MF);选择种植体尖端至下牙槽神经管上缘间距离小于2mm的8例患者的全景片,测量片中12颗种植体尖端至下牙槽神经管上缘间的距离,除以对应种植体的垂直放大率,计算其实际距离;记录该8例患者有无下唇和(或)颏部感觉异常。结果:①全景片中下颌磨牙区垂直放大率为1.27±0.02;②12颗种植体尖端距下牙槽神经管上缘之间的距离为(1.19±0.33)mm(0.69～1.89mm);③8例接受种植体植入的患者,无一例出现下唇或颏部感觉异常。结论:下颌磨牙区植入种植体的尖端与下颌管上缘之间保存完整的骨壁,是防止损伤下牙槽神经的最关键因素之一。     

微型种植体支抗和XIVE种植体在牙列缺损修复中的临床应用

目的：探讨用微型种植体作为正畸支抗压低伸长磨牙,同时用XIVE种植体修复对（牙合）缺失牙的可行性.方法：选择7例下颌第一磨牙缺失,对颌牙伸长＞2.5mm种植修复的患者.在对颌伸长的第一磨牙的近中腭侧和远中颊侧各植入1枚微型种植体.用橡皮链挂在颊、腭侧的种植体上,以压低伸长的对颌牙齿,定期更换并进行临床检查.同时缺牙区植入XIVE种植体,常规种植治疗.结果：7例患者中,1枚微型种植钉松动脱落,余6例患者伸长牙平均压低3mm,平均压低时间为5个月,经种植修复后均获得满意的临床效果.结论：针对下颌第一磨牙缺失对颌牙伸长较多的病例,微型种植体支抗和种植体的联合应用,能达到良好的修复效果.     

Evaluation of mandibular posterior single implants with two different surfaces: a 5-year comparative study

BACKGROUND: Anatomic and biomechanical limitations can jeopardize successful single implantation in the mandibular posterior area. To overcome the limitations, the design and the surface of the fixtures were modified. This study evaluated the cumulative survival rate (CSR) of mandibular molars replaced with a sand-blasted, large-grit, acid-etched (SLA) single implant or an anodized (ANO) single implant and examined associated factors, such as the surface treatment, position, and length and diameter of the implants. METHODS: One hundred ninety-three single implants restored with an SLA implant and 112 single implants restored with an ANO implant in the mandibular molar area were selected from subjects who had visited the Department of Periodontology, Dental Hospital of Yonsei University, from March 2001 through June 2006. In the SLA group, 123 and 70 implants were placed in the first and second molar area, respectively. In the ANO group, 55 and 57 implants were placed in the first and second molar area, respectively. The 1- to 6-year CSR of the SLA and ANO groups was calculated using the life-table analysis. In addition, associated factors, such as the surface treatment, position, and length and diameter of the implants, were compared and analyzed using the chi(2) test (P <0.05). RESULTS: Two of 193 implants in the SLA group failed, giving a CSR of 98.96%; four of 112 ANO implants failed, giving a CSR of 96.43%. There were no significant differences with regard to the surface treatment, position, and length and diameter of the implants. CONCLUSIONS: Despite the anatomic and biomechanical limitation in the mandibular posterior area, mandibular posterior single implants showed a high CSR during the observation period. Mandibular posterior single implants can be an effective and reliable treatment modality that is not affected by the surface treatment, position, or length and diameter of the implant.     

Medicolegal aspects of altered sensation following implant placement in the mandible

PURPOSE: Altered mandibular sensation following implant surgery may result in liability claims. Therefore the authors conducted a retrospective analysis of all liability claims related to persistent altered sensation following placement of mandibular implants reported to the Medical Consultants International (MCI) Company from 1992 to 1999. MATERIALS AND METHODS: Reports related to persistent altered mandibular sensation in 16 patients (12 women and 4 men) who underwent implant surgery in Israel were examined. The MCI files were retrospectively evaluated according to a structured form. The parameters studied included patient age and gender, implant location and length, imaging modality, and the time between actual damage and filing of a claim (ie, letter of demand or lawsuit). RESULTS: The time in months between actual damage and filing of claim ranged from 0 to 60 months (mean 21.5 months). No cases were found involving transient changes in sensation. The female/male ratio was 3:1. Implant length was equal to or longer than 13 mm in 6 of 7 implants placed in the molar region. In the premolar area, nerve injury was evident in 6 of 7 cases where implants shorter than 12 mm were used. CONCLUSIONS: Transient nerve injury rarely results in legal action. Maximum effort should be devoted to accurately determining the appropriate implant length in the mandible.     

Does crown/implant ratio influence the survival and marginal bone level of short single implants in the mandibular molar? A preliminary investigation consisting of 12 patients

Crown/implant (C/I) ratio has been proven to not affect the survival of the implants; however, it is also a fact that no evidence exists with regard to the use of single short implants in the mandibular molar. The aim of this study was to determine whether the crown/implant ratios of single implant‐supported fixed restorations on implants of 6–8 mm in the mandibular molar have an impact on the implant survival and marginal bone maintenance. Twelve short dental implants (6–8 mm) were installed and restored with single crowns, loaded after 3 months of healing. The restorations were divided according to crown‐to‐implant ratio into two groups: Group 1: C/I < 2·0 and Group 2: C/I ≧ 2·0. Alveolar bone loss was measured using CBCT scan, taken at the implant placement and after 12 months follow‐up from loading. Reduced implant/crown ratio shown no statistic significant differences on implant survival and the alveolar bone level compared with recommended implant/crown ratio. Within the limitation of this study, it can be concluded that reduced C/I ratio could be used as a substitute for recommended C/I ratio in severely mandibular atrophic residual alveolar ridges.     

单、双种植体修复下颌第一磨牙载荷状态下种植体周围组织应变及受力的实验研究

目的 探讨种植体数目在载荷条件下对下颌第一磨牙种植体周围组织的力学影响。方法 在下颌第一磨牙单、双种植体岁．持式义齿上部结构不同载荷点分别施加载荷，以电阻应变法对种植体额、舌两侧组织进行了应变测量和力学分析。结果 种植体周围组织应变与载荷的大小呈正相关；侧向力引起的种植体周围组织应变大于轴向力；载荷条件相同情况下，双种植体周围组织应变小于单种植体。结论 双种植体支持式义齿可以有效分散矜力、对抗侧向力，有利于种植体周围组织的长期稳定，因此，下颌第一磨牙缺失在颌骨条件允许的情况下应尽量选取双种植体设计。     

Histological comparison of bone to implant contact in two types of dental implant surfaces: a single case study

AIM: The purpose of this single case study was to evaluate the influence of different implant surfaces on human bone and osseointegration. METHODS AND MATERIALS: A 47-year-old partially edentulous woman received two experimental implants along with conventional implant therapy. Experimental implants placed in the mandibular ramus consisted of machined and anodized surfaces, respectively. After three months of healing, the experimental implants were removed and prepared for ground sectioning and histological analysis. RESULTS: The data demonstrate anodized implant surfaces present a higher percentage of osseointegration when compared to a machined surface in cortical human bone after a healing period of three months. CONCLUSION: This single case study suggests an anodized implant surface results in a higher percentage of bone to implant contact when compared to machined surfaced implants when placed in dense bone tissue. However, further investigations should be conducted.     

Study on the necessity for cross-section imaging of the posterior mandible for treatment planning of standard cases in implant dentistry

OBJECTIVE: To investigate whether cross-section imaging influences the planning and therapy of standard implant cases in the posterior mandible. MATERIAL AND METHODS: In a prospective study conducted over 16 months, the planned treatment (standard implant therapy without bone augmentation procedures in the premolar and molar regions of the mandible) was compared with the postoperative result in 50 randomly selected patients. Clinical examinations and panoramic radiographs were performed pre- and postoperatively, whereas cross-sectional tomography was performed only preoperatively. RESULTS: The vertical magnification factor in the panoramic radiographs was very constant pre- and postoperatively with 1 : 1.27 and in the spiral tomograms with 1 : 1.52. In 11 of 77 implant sites, the mandibular canal could not be evaluated in the spiral tomograms. The additional information from cross-sectional spiral tomography did not influence the original planning in 74 of 77 (96.1%) implant sites. Based on the postoperative panoramic radiograph, the average distance from the tip of the implants to the mandibular canal was 3.04+/-2.06 mm. In two cases (2.6%), transient postoperative altered tactile sensation of the mental nerve was found. CONCLUSION: The information from preoperative cross-sectional spiral tomography has minor impact on treatment planning in standard implant cases in mandibular premolar and molar regions. The clinical examination provides sufficient information for selecting implant diameter and the panoramic radiograph provides sufficient information for implant length selection.     

Long-term success of implants replacing a single molar

BACKGROUND: The aim of this study was to assess the long-term success and survival rates of implants replacing a single molar between two natural teeth and to evaluate the influence of implant characteristics on implant success. METHODS: The study was based on a consecutive cohort of 81 patients who received implants to replace a single molar between the years 1994 and 2004. Inclusion criteria for patients were having an implant replacing a molar between two natural teeth and follow-up data of at least 6 months. Data were recorded regarding the incidence of complications and success and survival rates of these implants. RESULTS: The range of follow-up was from 6 to 125 months (mean: 36 months). Smoking was reported by 18.5% of patients. The replacement of a mandibular molar was more frequent (87.7%), with 25.9% of the implants placed immediately after tooth extraction. Two implants were used to replace a single molar in seven patients (8.6%). The failure rate was 7.4% (six implants failed: three had broken necks, and three failed because of infection or bone loss). Complications included suppuration in 11.1% of implants and a pocket around the implant in two patients (2.5%). No relation was found among failure, complications, timing of implant placement, and smoking habits. CONCLUSION: A single implant can serve as a good long-term and predictable treatment modality to replace a single molar with low complication and failure rates.