An in vitro Investigation into Retention Strength and Fatigue Resistance of Various Designs of Tooth/Implant Supported Overdentures

Previously, the choice of prosthetic implant-retained overdentures has depended on data from previous studies about the retention-fatigue strength of the attachment system selected. Little or no data have been available on the correlation between the attachment system selected and the overdenture support configuration. The purpose of the present study was to evaluate the retention force and fatigue resistance of three attachment systems and four support designs of overdenture prosthesis. Four lower edentulous acrylic models were prepared and eight combinations of attachments groups were investigated in the study. These included: O-Rings with mini-dental implants (MDIs), Dalbo elliptic with Dalbo Rotex and fabricated flexible acrylic attachments with both MDI and Dalbo Rotex. The study was divided into four test groups: groups A and B, controls, and groups C and D, experimental groups. Control group A contained three overdenture supports: two free standing MDIs in the canine region and at the midline, and one simulated tooth root with Dalbo Rotex screwed in. Control group B contained four overdenture support foundations: two free standing MDIs in the right canine region and the first premolar region, and two simulated tooth roots with Dalbo Rotex screwed in at the same MDI position, but on the left side of the model. Experimental group C contained three overdenture support foundations: two free standing MDIs in the canine region and at the midline, and one simulated tooth root with MDI screwed in. Experimental group D contained four overdenture support foundations: two free standing MDIs in the right canine region and the first premolar region, and two simulated tooth roots with MDIs screwed in at the same MDI position, but on the left side of the model. Each group was further divided into two subgroups according to attachment type used. Five samples were prepared for each group. Retention force (N) values were recorded initially (0 cycles) and after 360, 720, 1440 and 2880 insertion and removal cycles. During the tensile test a cross-head speed of 10 mm/min was applied. Values of absolute force (AF) and relative force (RF) were statistically analyzed by two-way ANOVA and multiple comparison Tukey’s tests between groups and cycles periods. The results of fatigue tests showed a 50% reduction in retention force in the subgroups with flexible attachments. A triangular design of overdenture support foundations with O-Ring attachments revealed the lowest value of AF and a relatively high reduction in RF. The four overdenture support designs with flexible acrylic attachments improved the retention force and reduced the fatigue retention. Furthermore, the results of the investigation demonstrate that flexible acrylic attachments for both teeth and implant-supported overdentures offer a wide range of retention forces.

A novel bio-sensor for registration of biting force in occlusally reactive single mandibular implant overdenture

Mandibular single denture opposed by maxillary natural dentition showed a great problem. However, mandibular implant overdenture treatment has gained considerable recognition. Ten male patients with complete mandibular edentulous arch and opposing arch have full natural dentition. Patients were divided into two groups. All patients received two endosseous titanium implants. In Group I, patients were rehabilitated with conventional implant retained overdentures. While in Group II, Patients were rehabilitated with occlusal reactive implant overdentures. A Novel proposed biosensor was used to measure the amount of biting force on the implant retained overdenture. Quantitative electromyographic (EMG) signals of the masseter and anterior fibers of temporalis muscles were recorded, filtered and directly interfaced with a computer to represent the data graphically. The mean amplitude (μV), turn, and activity were recorded at the baseline and after three months. The results revealed an increase in the muscle activity in group II after three months as compared to group I. Significant difference in bilateral biting force at the premolar-molar area was found between group I and group II after three months. This study concluded that a resilient implant overdenture denture could be a desirable treatment in mandibular overdenture supported by two implants with resilient attachment and opposing natural dentition due to its easy fabrication and durability in use and increased muscle activity.

Class III Reversion with Immediate Complete Denture and Immediate Implant-Retained Overdenture: Case Report

With the increased life expectancy, complete dentures have been used in the treatment of edentulism progressively. It restores stomatognathic system functions, providing improvements in chewing, aesthetics, and phonetics. The aim was to report an oral rehabilitation of a patient with severe aesthetic and functional impairment, with Angle’s class III malocclusion. The patient sought the extension project of the School of Dentistry of the Federal University of Minas Gerais with aesthetic complaints. After clinical and radiographic evaluation, the proposed planning was immediate complete denture maxilla and immediate implant-retained overdenture in mandible. During clinical evaluation it was observed that the patient was Angle’s III. The rehabilitation was performed as proposed and at the end of the treatment, it was possible to revert the class III occlusal pattern to Angle’s I. The excellent maxillomandibular relationship was achieved, which ensured optimal facial aesthetics and functional condition. It was concluded that the immediate complete dentures and immediate implant-retained overdenture might be beneficial for restoring the aesthetics and function of patients with Angle’s class III malocclusion.

Biomechanical Analysis of Implant Assisted-Overdentures with Variations in the Attachments Systems

The aim of this study was to assess the stress patterns on the peri-implant zone and residual alveolar ridge in different overdenture attachment system designs by the photoelasticity method. Four attachments systems were tested: O-ring, ERA, Bar-clip, and Bar-clip/O-ring association. The prostheses were loaded with 100 N in five pre-determined points and the photoelastic model was evaluated by a circular polariscope. The anterior load, O-ring, and ERA showed better stress distribution in relation to the bars systems, which presented stress levels surrounding implants. The molar load, Bar-clip/O-ring association, presented the biggest stress concentration on the peri-implant region in relation to the others. When the second molar was loaded, there was a concentration of stress in the alveolar ridge in all situations analyzed. Within the limitation of this “in vitro” study, it could be concluded that there were biomechanical differences among the attachments systems analyzed, principally between isolated and the bars systems. The O-ring showed better stress distribution and the Bar-clip/O-ring showed higher stress concentration.

Swallowing threshold parameters of subjects with complete dentures and overdentures

Aim: To compare the chewing process and swallowing threshold parameters of subjects with complete dentures and overdentures with data obtained from subjects with complete natural dentitions. Metho-dology: The chewing process in terms of swallowing threshold parameters of four groups of subjects with complete dentures (all females) was quantified by sieving particles after chewing of an artificial test ‘food’ and compared with that of subjects with com-plete natural dentitions as a reference group (33 sub-jects). All subjects (except those of the reference group) had a complete denture in the upper jaw. Regarding the lower jaw two groups with complete dentures (with high (24 subjects), respectively low mandible (12 subjects)) and two groups with overdentures (implant-retained (22 subjects), respectively natural root supported (19 subjects)) were composed. Results: The ‘overdenture-implants’ group needed significantly more chewing cycles and time (mean: 45 cycles in 32 seconds) until ‘swallowing’ compared to the group with complete natural dentitions (mean: 26 cycles in 19 seconds until ‘swallowing’). Also the ‘complete denture-low mandible’ group needed sig-nificantly more cycles and time (mean: 52 cycles in 44 seconds) until ‘swallowing’ than the complete dentition group. In the ‘overdenture-natural roots’ group these outcomes (33 cycles in 24 seconds) were not significantly different compared with the complete dentition group. The ‘complete denture-high mandi-ble’ group (32 cycles in 26 seconds) needed not sig-nificantly more cycles until ‘swallowing’, however time until ‘swallowing’ was significantly longer com-pared to the complete dentition group. All denture groups had significantly larger mean particle sizes when ‘swallowing’ (sizes in the order of 3 mm) than the natural dentition group (about 2 mm). Conclusion: Despite efforts to compensate for a reduced chewing efficiency, subjects with complete dentures (including overdentures) had 50% larger median particle sizes when ‘swallowing’ compared to subjects with complete natural dentitions.

舌侧金属加强杆种植覆盖义齿的三维有限元分析

目的 通过三维有限元分析探讨舌侧金属加强结构义齿基托设计对无牙下颌种植修复义齿的生物力学影响,为无牙颌修复治疗提供参考。方法 构建舌侧金属加强结构与无加强结构两种义齿基托设计的2颗种植体支持Locator式覆盖义齿三维有限元模型,分别对后牙中央窝垂直施加150 N载荷、斜向施加150 N载荷以及对前牙垂直施加150 N载荷,模拟正中咬合、左右侧方咀嚼以及前牙切割食物时两种模型各组织的受力情况。结果 后牙及前牙垂直向加载时,两种义齿基托设计模型各组织的应力分布较为接近,所受最大应力差别在0~0.16 MPa之间;偏侧咀嚼时,未添加金属加强杆的义齿基托、种植体和黏骨膜应力集中范围,以及种植体、种植体周围骨最大受力明显大于添加金属加强杆模型,所受最大应力差别在0.59~2.99 MPa之间。结论 在义齿基托舌侧添加金属加强杆,可以起到应力分散的作用,或可在一定程度上减小骨吸收及基托折断的风险。

48例Locator种植覆盖全口义齿5年临床修复效果评价

目的:观察Locator按扣式种植覆盖全口义齿的长期临床修复效果。方法:选择2016—2017年北京大学口腔医院门诊部采用Locator按扣式种植覆盖全口义齿修复的无牙颌患者48例,其中双颌全口义齿修复21例,单颌27例,共植入种植体230颗。观察种植体的留存率、种植体周黏膜探诊出血(BOP)、种植体周牙槽骨垂直吸收高度变化、义齿基托折裂和人工牙脱落折断等并发症,以及义齿固位力变化等。采用SPSS 13.0软件包对数据进行统计学分析。结果:在5年观察期间,5颗种植体脱落,1颗前牙区窄颈种植体颈部折断,12颗失访,种植体存留率为97.25%。种植修复后1年,48颗种植体周黏膜探诊出血(BOP+)(21.4%),平均出血指数(BI)为0.21±0.42,前牙区高于后牙区。种植体周牙槽骨垂直吸收高度为(0.21±0.35) mm,义齿基托折断2例。修复后5年,163颗种植体周黏膜探诊出血(BOP+)(76.89%),BI为1.00±0.70,种植体周牙槽骨垂直吸收高度为(0.58±0.85) mm;种植体周黏膜探诊出血指数与牙槽骨垂直吸收高度在男女之间、前牙区与后牙区之间均无统计学差异(P>0.05)。1年观察期和5年观察期间,种植体周黏膜平均出血指数、种植体周牙槽骨垂直吸收高度前后比较有显著差异(P<0.01)。义齿折裂17例,折裂率为26.15%,人工牙脱落折断率为16.92%,多发于前牙中线区及Locator基台附着体安放位置,因固位力下降首次更换Locator基台固位垫圈平均(34.2±10.3)个月。结论:Locator按扣式种植覆盖全口义齿有良好的临床修复效果。并发症多见于种植体周黏膜探诊出血和垂直向骨吸收,随着戴用时间延长有逐渐加重的趋势。其次是义齿基托折裂及人工牙脱落与折断,种植体脱落及折断。提示义齿制作时应加强金属支架在Locator基台位置和前牙中线区的强度,前牙区尽量避免使用窄径种植体。

Clinical evaluation of implants in patients with maxillofacial defects

AIM: To show the efficacy of reconstruction and rehabilitation of large acquired maxillofacial defects due to tumor resections and firearm injuries. METHODS: The study group comprised of 16 patients(10 men and 6 women) who were operated on because of their maxillofacial defects under local and general anesthesia between June 2007 and June 2011. Prosthetic treatment with the aid of dental implants was performed for all of the patients. Eight patients received an implant supported fixed prosthesis; six patients received implant supported overdentures and two patients received both. Patients were followed up postoperatively for 1 to 4 years. Implant success and survival rates were recorded. Panoramic radiographs were taken preoperatively, immediately after surgery, immediately after loading and at every recall session. Peri-implant and prosthetic complications were recorded. Subjects were asked to grade their oral health satisfaction after treatment according to 100 mm visual analog scale(VAS) and the oral health related quality oflife of the patients was measured with the short-form Oral Health Impact Profile. RESULTS: Five implants(3 in the mandible, 2 in the maxilla) in five patients were lost, while the other 53 survived, which brings an overall survival rate of 91.37% on the implant basis, but 68.75% on patient basis. All the failed implants were lost before abutment connection and were therefore regarded as early failures. For all failed implants, new implants were placed after a 2 mo period and the planning was maintained. The mean marginal bone loss(MBL) was 1.4 mm on the mesial side and 1.6 mm on the distal side of the implants. Five of the implants showed MBL > 2 mm(mean MBL = 2.3 mm) but less than 1/2 of the implant bodies and therefore were regarded as not successful but surviving implants. The VAS General Comfort mean score was 85.07, the VAS Speech mean score was 75.25 and the VAS Esthetics mean score was 82.74. No patient reported low scores(score lower than 50) of satisfaction in any of the evaluated factors. The mean of OHIP-14 scores was 5.5. CONCLUSION: Although further follow up and larger case numbers will give more information about the success of dental implants as a treatment modality in maxillofacial defects patients, the actual results are encouraging and can be recommended for similar cases.

p38MAPK在周期性压应力下对颌骨成骨细胞分化的作用

目的探讨p38丝裂原活化蛋白激酶(p38 mitogen activated protein kinases,p38 MAPK)在周期性压应力作用下对无牙颌种植覆盖义齿牙槽嵴成骨细胞分化中的作用机制,为无牙颌骨组织的改建和种植覆盖义齿修复提供理论依据。方法构建无牙颌牙槽嵴成骨细胞力学刺激模型,采用简单随机抽样法将力学刺激模型分为对照组(15%压应力)和阻断组(15%压应力+阻断剂)。加载参数设定为细胞拉伸形变率15%,加力时间均为6 h、12 h、24 h。CCK-8检测牙槽骨成骨细胞增殖活性;Western-blotting检测p38 MAPK差异性表达,q PCR检测碱性磷酸酶(Alkaline phosphatase,ALP)和破骨细胞分化因子(Receptor activator of nuclear factor-κB ligand,RANKL)的差异性表达变化。结果15%压应力使得牙槽嵴成骨细胞增殖活性增加,加力12 h细胞增殖活性最高;对照组加力12 h后,P-p38MAPK蛋白、ALP mRNA、RANKL mRNA的分别表达量均明显过于6 h(P<0.05);加力24 h P-p38MAPK蛋白表达量均比6 h、12 h显著升高(P<0.05);加力24 h ALP mRNA、RANKL mRNA的表达量比6 h显著升高(P<0.05),比12 h有一定程度升高(P>0.05)。阻断组加力6 h、12 h、24 h P-p38MAPK蛋白、ALP mRNA、RANKL mRNA的表达量分别均明显低于对照组相应的时间点(P<0.05)。结论p38MAPK信号转导通路参与了周期性压应力下无牙颌种植覆盖义齿牙槽嵴成骨细胞分化的过程,参与无牙颌种植覆盖义齿修复骨组织改建过程。

先天缺牙患儿活动和种植修复1例

先天缺牙影响儿童生长颌面部发育,需要早期对患儿进行包括义齿修复在内的多学科序列治疗,保障软硬组织有足够的力学刺激。本文报道1例先天缺牙患儿序列治疗中通过活动义齿和种植义齿进行缺失牙修复的阶段治疗过程。

种植覆盖义齿与固定义齿治疗无牙颌患者的效果比较

目的对比种植覆盖义齿与固定义齿治疗无牙颌患者的效果。方法回顾性分析2018年7月至2020年9月郑州市第三人民医院收治的62例无牙颌患者,并根据采用的种植修复方案进行分组,将接受种植固定义齿修复的患者纳入对照组(30例),将接受种植覆盖义齿修复的患者纳入观察组(32例),因失访退出研究2例,最终完成研究30例。修复完成后随访1 a,行常规修复体检查与效果评价,测定菌斑指数、骨吸收、修复体成功率、患者满意度评分、口腔健康相关生命质量。结果两组修复完成后1 a的菌斑指数比较,差异无统计学意义(P>0.05);种植术后3个月、修复治疗后1 a,两组骨吸收情况比较,差异无统计学意义(P>0.05)。对比两组修复体成功率,差异无统计学意义(P>0.05)。两组固位、发音、咀嚼、舒适评分比较,差异无统计学意义(P>0.05);观察组美观、总体满意度评分高于对照组,差异有统计学意义(P<0.05);随访1 a,观察组口腔影响程度量表(OHIP-14)中文版评分中Q1、Q5、Q7评分及总分比对照组低,Q6、Q10评分比对照组高,差异有统计学意义(P<0.05)。结论种植覆盖义齿与固定义齿均可有效治疗无牙颌患者,成功率较高,其中种植覆盖义齿患者的美观及总体满意度评分较高,并可提高患者的口腔健康相关生命质量。

种植覆盖义齿与种植固定义齿对无牙颌患者的临床疗效

目的探究种植覆盖义齿与种植固定义齿对无牙颌患者的临床疗效。方法选取2018年10月至2020年5月本院收治的84例无牙颌患者作为研究对象,依照患者入院先后顺序分为两组,每组42例。覆盖组行种植覆盖义齿治疗,固定组行种植固定义齿治疗,比较两组种植体周围的菌斑指数及种植成功率,探诊龈沟出血情况,评估两组患者的口腔健康主观感受。结果重复测量方差分析结果显示,修复后1、3、6个月,两组组间、时间、交互菌斑指数(PLI)评分及出血指数(BI)评分比较差异无统计学意义;组内比较:修复后1、3、6个月,两组PLI评分各时间点两两比较差异无统计学意义;修复后6个月,两组BI评分均低于修复后1个月(P<0.05),两组修复后3个月与修复后1、6个月比较差异均无统计学意义;组间比较:修复后1、3、6个月,两组PLI评分及BI评分比较差异均无统计学意义。覆盖组种植成功率(97.09%)稍高于固定组(95.86%),差异无统计学意义;覆盖组口腔健康影响程度量表(OHIP-14)评分低于固定组,差异有统计学意义(P<0.05)。结论无牙颌患者开展种植覆盖义齿和种植固定义齿治疗均有较显著效果,种植覆盖义齿治疗的患者主观感受较好、满意度更高,两种种植修复技术优缺点并存,在临床治疗中需要患者结合实际情况选择合适的修复方案。

种植体-杆卡式附着体固位的覆盖全口义齿

目的:总结和评价种植体-杆卡式附着体在覆盖全口义齿中的应用经验和效果。方法:将种植体与杆卡式附着体结合,以粘膜支持式、混合支持式和种植体支持式3种设计形式,为46例患者制作种植式全口覆盖义齿,并检查义齿的固位力和稳定性;同时采用修复体测力仪对其中15例患者义齿的固位效果进行定量评价。结果:3种设计均可达到良好的固位效果,其中混合支持式和种植体支持式的稳定、支持效果更好;应用2～3只尼龙卡可分别为覆盖义齿提供10～15N的固位力。结论:种植体-杆卡式附着体固位的全口覆盖义齿是无牙颌修复的非常有效的方式。

总义齿、覆盖义齿和种植覆盖义齿修复后患者满意度的比较研究

目的 比较总义齿 (CD)、覆盖义齿 (COD)和种植覆盖义齿 (IOD)修复后的患者满意度。方法 选取CD、COD和IOD修复后的患者各 14例 ,对三组患者分别进行满意度的问卷调查。结果 三组患者对义齿总的满意度的差异没有显著性 ,对咀嚼功能的满意度IOD组显著高于CD组。三组患者戴用旧义齿的经验没有显著差异。义齿的松动和食物受限情况IOD组明显少于CD组 ,而义齿修复后的牙槽嵴疼痛和感觉咀嚼无力的情况三组间没有显著差异。结论 IOD修复后患者对咀嚼功能的满意度较CD修复的患者高 ,出现的问题少 ,是一种较好的修复无牙颌的方法。

全下颌牙种植义齿及支持组织应力的三维有限元分析Ⅵ.不同上部结构对覆盖种植义齿应力分布的影响

采用三维有限元方法 ,考察了不同的上部结构设计 ,包括套筒冠、杆卡式附着体、改良杆卡式附着体对全下颌种植覆盖义齿及其支持组织在正中情况下应力分布的影响。结果发现杆卡式附着体的使用可降低种植体及剩余牙槽嵴表面的应力 ,但使界面应力增加。改良杆卡式附着体不利于种植体及骨界面的应力分布。

种植覆盖总义齿的满意度分析

目的:了解种植覆盖总义齿患者对修复体的满意度。方法:共完成38件种植覆盖总义齿,在该研究中应用满意度的问卷调查,以分析种植覆盖总义齿的合理性和稳定性。结果:患者对种植覆盖总义齿的固位、舒适和咀嚼效能满意度较旧义齿明显提高。结论: 种植覆盖总义齿的临床效果满意。

下颌种植覆盖义齿修复后满意度的调查分析

目的比较牙列缺失患者行下颌半口义齿和下颌种植覆盖义齿修复的主观感受。方法对16例戴用下颌半口义齿后又行下颌种植义齿修复的患者,采用自拟修复前初诊问卷和种植修复后问卷调查,由患者本人就诊时填写。结果种植固定义齿与下颌半口义齿在舒适、功能、固位等方面存在明显差异。结论牙列缺失患者行下颌杆卡式种植覆盖义齿,较下颌半口活动义齿修复能更好地满足患者需求,获得高质量的义齿。

全下颌牙种植义齿及支持组织应力的三维有限元分析Ⅴ.种植体类型对覆盖种植义齿应力分布的影响

采用三维有限元的方法 ,分别考察了由柱状和叶状种植体支持的全下颌种植覆盖义齿、种植体、骨界面及牙槽嵴在三种位下的应力分布情况。发现叶状种植体及其骨界面的应力较高 ,不利于应力分布。

总义齿、覆盖义齿和种植覆盖义齿修复后咀嚼肌功能活动的比较研究

目的 比较总义齿 (CD)、覆盖义齿 (COD)和种植覆盖义齿 (IOD)修复后患者嚼肌和颞肌前后束肌电活动 ;用咀嚼肌的收缩模式和协同方式分析肌电活动的差异。方法 分别选取CD、COD修复后的患者各 14例和IOD修复后的患者 12例 ,记录左右侧嚼肌、颞肌前束、颞肌后束在下颌休息位、大力咬合和咀嚼小枣和杏仁时的肌电图。测量肌电活动的幅值 (A值 )、电位方向转折次数 (T值 )、积分值 (Ar值 )。结果 COD组在咀嚼枣时颞肌前束的A值显著高于IOD组和CD组 ,Ar值显著高于CD组 (P <0 .0 5 ) ,颞肌后束的T值显著高于CD组和IOD组 (P <0 .0 5 )。三组患者在休息状态下和咀嚼运动的活动期 ,嚼肌与颞肌Ar值差值的均值均为负值 ;大力咬合时CD组为正值 ,IOD组和COD组均为负值。大力咬合和咀嚼周期活动期差值的绝对值为COD组显著高于IOD组和CD组 (P <0 .0 5 )。结论 CD修复后患者咀嚼肌在不同的咀嚼运动中多采用不固定用力方式 ,咀嚼肌的收缩模式有产生疲劳的趋势 ;IOD修复和COD修复后则具有相对高效的收缩模式。

下颌骨腓骨移植联合牙种植术后的覆盖义齿修复1例

本文报道1例28岁男性患者下颌骨腓骨移植联合牙种植术的治疗。患者因下颌骨成釉细胞瘤切除左侧部分下颌骨并行血管化单层腓骨移植,术后2年于腓骨移植区植入4颗种植体,采用纯钛铸造杆+Locator附着体+覆盖义齿方式进行修复,取得了良好的效果。本病例提供了一种腓骨移植联合牙种植术修复的可行方案,并通过文献复习阐述了修复方式的特点,以期提高腓骨移植患者的修复效果。