The mandibular complete overdenture

Mandibular complete overdenture treatment has been available for decades, but its use was limited when the treatment relied on retained teeth as overdenture abutments. This treatment, however, is currently experiencing more popularity than ever before. In fact, dentistry may be experiencing a philosophical shift, in which mandibular implant overdenture treatment may become the new standard of care for the treatment of the edentulous mandible. Practitioners are looking for simplified treatments that can provide cost-effective alternatives to more complex implant prosthodontic procedures. Implant overdentures provide a strong return for the investment in treatment time and expense and are a treatment suited to the lower socioeconomic status of many edentulous patients. The clinical outcome of this treatment is significantly better than that achieved with conventional mandibular dentures, especially when patients are experiencing technical problems because of compromised prosthesis retention or stability.     

Stress distributions in maxillary bone surrounding overdenture implants with different overdenture attachments

In this study, effects of different overdenture attachments on the stress distributions in the maxillary bone surrounding the overdenture implants are studied. Four different types of attachment are considered. They are rigid Dalbo Stud, movable Dalbo Stress Broken, movable Dalro, and movable O-ring attachments. Three-dimensional finite element analysis was conducted with commercial package to obtain the stress distributions in the maxillary bone. Varying the attachment types and angle of inclination of load, the stress distributions in the portions of compact bone and trabecular bone were monitored separately. The analysis was conducted by assuming two different boundary conditions at the interface between cap and overdenture abutment in order to evaluate influence of interface boundary condition on stress distribution in the maxillary bone. They were perfect bonding condition and contact with friction at the interfaces. However, it is preferable to assume perfect bond condition at the interface for rigid type attachment systems and contact with friction at the interface for movable type attachment systems. From the numerical results, it was found that the load transfer mechanism of the implant system is altered significantly by the types of the overdenture attachment and also special care must be taken to assign proper boundary conditions at the interface for the analysis. The movable type Dalro attachment generated the highest maximum effective stress in the maxillary bone among the models under the same inclined loading condition for contact with friction. The rigid type Dalbo Stud attachment generated the smallest maximum effective stress in the maxillary bone among the models under the same inclined loading condition for perfect bonding condition.     

A maxillary implant overdenture that utilizes angle-correcting abutments

Placement of dental implants to enhance complete denture stability and retention is a well-accepted treatment modality. Most implant overdenture abutments and related components require parallelism within approximately 10 degrees to function properly. Non-parallel implant placement as a result of flared maxillary bone may preclude the use of conventional implant overdenture abutments, requiring the use of costly custom abutments or bar prostheses. A case report is presented that illustrates the use of a new, 2-piece, angled overdenture abutment to accommodate non-parallel implant placement.     

Modular transitional implants to support the interim maxillary overdenture

It has been reported that for implants to become osseointegrated, they must heal in the absence of functional loads for 4 to 6 months. To address the need for undisturbed healing and patient demand for uninterrupted immediate function and esthetics, the Modular Transitional Implant and Prosthetic System has been developed. This case report describes the use of transitional implants to support a removable maxillary overdenture, including methodology and the advantages and disadvantages of the system. The histomorphometric analysis of one of these transitional implants and its surrounding osseous tissue showed a 45% bone-to-implant interface after 6 months of functional loading. The transitional implant system is a sound and economical method of immediate patient restoration that allows for the protected healing of submerged implants.     

Retention of maxillary implant overdenture bars of different designs

STATEMENT OF PROBLEM: The specific degree of retention for overdenture attachments is unknown in relation to design, location, and alignment to supporting dental implants. PURPOSE: The purpose of this study was to evaluate the initial retention characteristics of 5 implant maxillary overdenture designs under in vitro dislodging forces. MATERIAL AND METHODS: A simulated edentulous maxilla was fabricated with 4 screw-type 3.75 x 13-mm implants anteriorly. Five overdenture designs with the following attachments were evaluated: 4 plastic Hader clips with an EDS bar; 2 plastic anterior Hader clips with an identical EDS bar; 2 Hader clips with 2 posterior ERA attachments; 3 Zaag attachments on a bar; and 4 Zaag attachments with no bar. Overdentures were fabricated with full palatal coverage. Each design was subjected to 10 consecutive retention pulls on a universal testing machine. Data were subjected to analysis of variance and t tests to determine differences. RESULTS: The highest average value after 10 pulls was 19.8 lb for the combination ERA and Hader clip design. The lowest retentive values were recorded for the 2 and 4 Hader clip designs (5.08 +/- 0.89 lb and 5.06 +/- 0.67 lb, respectively). Retention decreased over the course of consecutive pulls for all designs, especially for the most retentive designs. The smallest retention decrease occurred with the least retentive designs. CONCLUSION: The results of this in vitro study suggest that the precise selection and placement of attachments may affect the clinical success of maxillary implant-retained overdentures.     

Implant complications and failures: the complete overdenture

The implant-retained overdenture has been advocated as an effective method of restoring the edentulous patient with an appliance that offers significant benefits over conventional prosthetics. However, the success and survival of such appliances have been shown to vary considerably, depending on which jaw is treated: implants supporting overdentures in the maxilla have a significantly higher failure rate. The restoration also requires considerable maintenance, which is both time consuming and costly. The purpose of this paper is to look at common restorative complications and maintenance problems following the placement of dental implants to support an overdenture. A number of implant systems have been reviewed and the results of the authors' clinical experiences with referred and their own cases are reported.     

63副磁性附着体在全口覆盖义齿中的临床应用体会

目的:评价磁性附着体应用于全口覆盖义齿修复的效果。方法:用63副Magfit和Magdisc磁性附着体为28例牙列缺损患者进行覆盖义齿修复,并随访观察2年。结果:63副磁性附着体中1副失败,9颗基牙出现龈缘炎,未发现继发龋、基牙松动、义齿折裂、根面板脱落;所有覆盖义齿固位效果满意。结论:Magfit和Magdisc磁性附着体能有效改善覆盖义齿的固位,并发症少,具有较好的应用前景。     

Single maxillary complete denture

The single maxillary denture is a complex prosthesis that requires a complete understanding of the basics of denture occlusion. Theilemann's formula must be applied to each individual patient, and appropriate treatment must be taken to assure complete balance in all excursive movements. The basic principles of retention, stability, and support should not to be taken for granted, and steps must be completed so that all components are working in harmony for success of the maxillary denture. Treatment of various patients has been illustrated to allow the reader to comprehend better the modalities that can be employed for preparing the oral environment before denture insertion thereby ensuring better success in treating these classes of patients.     

Duplicating maxillary complete dentures

A technique for duplication of a maxillary complete denture has been presented. This technique requires no special equipment and can be easily completed in the dental office.     

下颌磁性附着体覆盖全口义齿的临床疗效观察

目的：调查磁性附着体覆盖全口义齿修复的临床效果。方法：对9例磁性附着体患进行义齿满意度问卷调查分析，并检查患基牙临床指征及牙周微生态的情况。结果：患对磁性附着体义齿固位稳定功能满意度最高；基牙的微生物组成与正常值相比有一定的变化，但戴牙前后基牙临床指标无明显变化。结论：适当的修复以及良好的口腔卫生条件下，下颌磁性附着体覆盖全口义齿是一种有效、可行的修复方式。     

太极扣附着体全口覆盖义齿的咀嚼效果及固位力测试

目的：定量测量太极扣全口覆盖义齿与普通全口覆盖义齿在咀嚼效率和固位力方面的差异。方法：随机选择制作覆盖义齿的患者10例,完成太极扣全口覆盖义齿制作,于安装太极扣附着体前后行咀嚼效率和固位力测试,并进行自身对照研究。结果：安装太极扣后全口覆盖义齿的固位力和咀嚼效率均增加,具有统计学意义（P〈0.05）。结论：太极扣全口覆盖义齿与普通全口覆盖义齿相比,咀嚼效率和固位力均有显著提高。     

冲击载荷下骨外段种植基桩不同高度对下颌覆盖总义齿应力分布的影响

目的 分析骨外段种植基桩高度不同对下颌种植覆盖总义齿应力分布的影响。方法 应用ＣＴ扫描法建立下颌种植覆盖总义齿三维有限元模型,分析冲击载荷下骨外段种植基桩高度不同对下颌种植覆盖总义齿应力分布的影响。结果 随种植基桩高度的降低,种植体内部及种植体软硬组织界面应力分布更为均匀。结论 在保证义齿固位稳定的前提下,在一定范围内降低种植体骨外段基桩高度有利于保护种植体及其周围软硬组织健康。     

磁性附着体在单颌全口覆盖义齿中的5年临床效果观察

目的：研究磁性附着体在单颌全口覆盖义齿中的临床修复效果。方法：20例患者,单颌选择1-4个基牙放置磁性附着体制作全口覆盖义齿,其中上颌全口覆盖义齿患者5例,下颌全口覆盖义齿患者15例,共采用41个磁性附着体。在修复后1个月、3个月、6个月、1年、2年、3年、4年及至今5年分别进行回访复查,主要观察固位体周围牙龈的健康状况,基牙松动度,继发龋,义齿的固位,稳定性,咀嚼效率的变化及舒适度。对义齿咀嚼效率的变化及舒适度衡量主要依赖患者的直接主观感受。结果：患者对义齿的舒适性和稳定性均表示满意,3个基牙出现松动,2个基牙出现继发龋,1个磁体脱落,其余良好。结论：采用磁性附着体的单颌全口覆盖义齿可以提高义齿的舒适性和稳定性。     

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无牙颌（edentulous jaw）是指各种原因导致的上颌或（和）下颌牙列缺失后的颌骨,常规使用全口活动义齿修复。然而针对牙弓内仅存个别患牙的情况,如果患牙经过牙髓、牙周的系统治疗后可利用,覆盖义齿修复则是常用修复方式。但由于大多数牙齿缺失、牙槽嵴萎缩,致使义齿的固位力十分有限,患者修复后咀嚼效果仍然不理想。