Masticatory function with implant-supported overdentures

The type of attachment that is used in implant-supported mandibular overdentures may influence the retention and stability of the prosthesis and, thus, masticatory function. In this within-subject cross-over clinical trial, we examined the hypothesis that greater retention and stability of the overdenture improve the masticatory function. Eighteen edentulous subjects received 2 oral implants, a new overdenture, and, successively, 3 different suprastructure modalities: magnet, ball, and bar-clip. Masticatory performance, masticatory efficiency, and swallowing threshold were measured. The masticatory function significantly improved after implant treatment with each of the 3 attachments. We observed small differences in masticatory function among the 3 attachment types: slightly better masticatory performance with ball and bar-clip than with magnet attachments. The number of chewing cycles until swallowing hardly decreased after implant treatment. We conclude that significantly better masticatory performance, combined with a slightly smaller number of chewing cycles after implant treatment, results in smaller food particles being swallowed.     

Classification system for implant-supported overdentures.

A classification system for implant-supported overdentures is proposed in this article. Various types of implant-supported overdentures have been described in the literature, but there is considerable difference in the function of these designs. For example, an overdenture supported by freestanding implants does not have the retentive elements provided by a bar and, therefore, is less retentive than an overdenture supported by a straight bar. If more than two implants are configured in an arch, and if indirect retention is incorporated into the bar and overdenture design, function is improved over that of a straight-bar design. Another classification of overdenture is one that receives all of its support from an implant-supported bar with tissue contact to provide a mucosal seal. This tissue contact does not provide any actual support. By accepting and using this classification system, the clinician can design an overdenture that is appropriate for the functional requirements of the patient being treated.     

Fiber-reinforced composite framework for implant-supported overdentures

This article presents a new method for fabricating a framework for an implant-supported overdenture using unidirectional fiber-reinforced composite. This procedure eliminates the need for a traditional metal alloy framework. The fiber-reinforced composite framework has the advantages of lower cost, less time and materials needed during fabrication, minimal potential for toxicity to the technician and patient, and a more esthetic metal-free final result.     

Metal reinforcement for implant-supported mandibular overdentures

Complete and implant-supported mandibular overdenture bases can be a problem because they are especially prone to fracture. Metal reinforcement of the denture base can substantially reduce the incidence of fracture. This article describes 2 methods of reinforcing mandibular overdentures. The advantages of these methods and their indications are discussed.     

Removable partial overdentures

A technique for applying the overdenture concept to removable partial denture construction has been presented. Endodontically treated abutments are prepared with cast gold posts and copings over which removable partial dentures with conventional components are fabricated. No special materials or complicated laboratory techniques are required, and the maintenance and repair problems of precision attachments are avoided. A variety of potential uses and advantages of the technique are discussed.     

Patient evaluation after treatment with maxillary implant-supported overdentures

Purpose: To evaluate and compare outcome among patients after implant overdenture treatment in the maxilla. Materials and Methods: The study sample comprised two groups of patients: group 1, in which the patients were planned for overdenture treatment, and group 2, in which the patients originally were planned for a fixed prosthesis in the maxilla but had overdenture treatment owing to implant failures, resulting in an insufficient number of implants to support a fixed prosthesis. All patients treated with maxillary implant‐supported overdentures in the Department of Prosthetic Dentistry, Central Hospital, Skövde, Sweden, between 1993 and 2002 received a questionnaire at their yearly follow‐up visit with nine questions related to their treatment. All questions had visual analogue scale response alternatives ranging from a negative to a positive opinion. Results: Nineteen patients, 10 in group 1 and 9 in group 2, completed the questionnaire, yielding a response rate of 86%. Both groups expressed a high satisfaction rate, and few regretted their choice of treatment. Patients planned for overdenture treatment (group 1) reported significantly fewer speech problems after treatment compared with those originally planned for a fixed prosthesis (group 2, p < .05). No other significant differences between the two groups were seen. Conclusion: Within the limitations of the present study, it can be concluded that maxillary implant overdenture treatment may be considered a viable option among patients with an insufficient number of implants for a fixed prosthesis.     

Laboratory processing of housing-retained attachments for implant-supported overdentures

The use of a metal housing-retained attachment for implant-supported overdentures: (1) facilitates easy removal and replacement of a matrix attachment during routine recall examinations, and (2) ensures correct alignment and retention to the implant-supported bar assembly. This article describes a laboratory technique for processing the bar assembly (without allowing acrylic resin to seep under it) with the master cast invested in the metal flask. The technique ensures a precise fit of retentive attachments at the delivery of the overdenture to the patient.     

Spark erosion implant-supported overdentures: clinical and laboratory techniques.

Overdentures can be utilized effectively in treatment plans involving implants. Usually soft tissue support is necessary, which requires a conventional denture base. Implant-supported overdentures do not require conventional denture base extension unless necessitated by functional or esthetic considerations. With fixed-detachable hybrid dentures, flanges can often interfere with home care procedures. Spark erosion overdentures meet the requirements for esthetics, phonetics, retention, and support and also allow accessibility for proper patient oral hygiene. This article reviews the advantages and disadvantages of the spark erosion overdenture and provides guidelines for the fabrication of this type of prosthesis.     

Posterior jaw bone resorption in osseointegrated implant-supported overdentures

For several years, osseointegrated implant-supported overdentures have been used in the rehabilitation of full edentulism with excellent results, at least in the lower jaw. This study involved 3 groups of patients with different prosthetic reconstructions: (1) mandibular overdentures supported by 2 implants connected by a bar (30 patients), (2) mandibular fixed prostheses supported by 4-6 implants (25 patients) and (3) mandibular complete dentures without implant support as controls (85 patients). The primary aim of this study was to examine on orthopantomograms (by means of the area index to minimize distortion and magnification errors), posterior mandibular ridge resorption in the 3 treatment groups. The present data demonstrated a minimal posterior mandibular ridge resorption in patients with fixed implant-supported prostheses. A more considerable posterior ridge resorption was observed in the complete denture group and especially in the overdenture wearers. For the latter, the annual posterior jaw bone resorption after the post-extraction remodeling period of 6 months, was 2- to 3-fold that of full denture wearers. When patients were edentulous for more than 10 years, the difference between the 2 latter groups disappeared. It is suggested that although the overdenture design on 2 implants offers advantages from a financial and failure rate point of view, its indications in younger patients should cautiously be evaluated in a long-term perspective concerning posterior mandibular bone resorption.     

Histological changes in edentulous oral mucosa under implant-supported overdentures

The microscopic characteristics of the mucosa covering the alveolar ridge that supports a complete denture have long been studied. In this paper, any histological changes in mucosa loaded by a denture before and after a denture has been anchored by implant onto the bone were followed. The results suggest that mechanical loads improve trophism of mucosa, and that fixing a denture to implants leads to a more uniform distribution of loads.     

两种附着体种植覆盖义齿的临床效果比较

目的 评价球帽附着体和Locator 附着体应用于无牙颌患者种植覆盖义齿的临床效果.方法 选择无牙颌行种植覆盖义齿修复患者67例,共植入150颗种植体,附着体类型为球帽或Locator.对患者定期复查,检查种植体的牙周袋探诊深度(PPD),菌斑指数(PLI),牙龈指数(GI)和龈沟出血指数(BI),测量边缘骨吸收值(MBL).患者分为球帽组、球帽改Locator组和Locator组,对PPD值、MBL值和PLI、GI、BI分别进行3组间比较.使用Digimizer图像分析软件进行影像学测量,采用SPSS17.0软件进行统计分析.结果 150颗种植体修复前成功率为95.88%,累计存留率为92.97%.PPD值平均为(2.16 ± 1.02)mm,球帽组与改做组间无显著差异,Locator组的PPD值明显低于另2组.PLI、GI和BI的组间差异均无统计学意义.MBL值平均为(0.92 ± 0.61)mm,改做组的MBL值明显高于另2组,而Locator组的MBL值最低.结论 Locator式种植覆盖义齿比球帽式种植覆盖义齿的临床效果具有一定优势.     

Retention mechanisms and prosthetic complications of implant-supported mandibular overdentures: long-term results

Background: Although many studies report high survival rates of mandibular implants supporting an overdenture, complications with prostheses and the need for prosthetic maintenance are not so well documented. Purpose: The purpose of the present study was to analyze three categories of prosthetic complications in relation to the type of retention mechanism for overdenture connection to the implants (ie, rigid or resilient). Materials and Methods: One hundred nineteen patients with a total of 258 implants participated in the study. They had been monitored regularly during an observation period of 5 to 15 years (mean 9.3 yr). Seventy‐five patients had a resilient retention device (ball anchors or a round clip bar); 44 patients had a rigid bar with or without distal extensions. The incidence and rate of complications were calculated for the overall‐ and for the 2‐ and 5‐year observation periods. Comparisons were made between the three categories of maintenance and the two types of retention. A Kaplan‐Meier analysis was applied for calculations of changes of the retention mechanism. Results: The mean number of complications per overdenture during the entire observation period was 3.5; this did not differ statistically between the two retention groups. Some significant differences were found only for the 2‐ and 5‐ year period. Broken, loose, or lost female parts were more frequently observed with resilient devices, as were repairs and relining of the resin denture base, whereas tightening of bar retainers was more typical with rigid bars. A change from a resilient retention device to a rigid bar was performed more often than vice versa but not at a statistically significant level. Conclusion: Although these long‐term results do not indicate a significant difference between the retention groups, a slight superiority of the rigid bar is suggested.     

The masticatory efficiency of mandibular implant-supported overdentures as compared with tooth-supported overdentures and complete dentures

This study assesses the comparative masticatory efficiency (CME) of mandibular implant-supported overdentures (ISOs) to tooth-supported overdentures (TSOs) and complete dentures (CDs). Three groups of patients in equal numbers were evaluated by assessing chewing efficiency, and the results were correlated with tracings of mandibular excursion (ME) and electromyographic (EMG) computerized analysis. CME was measured by utilizing standardized portions of 2 food staples with fixed masticatory sequencing. In a following session, utilizing the same fixed masticatory sequence, tracings of ME and EMG of the masseter and temporal muscles were recorded and analyzed. The results revealed that the ISO provided the greatest degree of efficiency, followed by the TSO and then the CD group. CME is more correlated to ME and less correlated to EMG.     

下无牙颌种植覆盖义齿研究新动态

由于下颌骨牙槽嵴面积较小、附着肌较多、活动性大及受唾液和舌的影响,下颌牙列缺损伴严重牙槽骨吸收患者应用传统全口义齿修复效果较差,常常需要借助其他装置来改善义齿的固位和稳定。种植覆盖义齿不但可增加义齿的固位稳定,还可获得依靠种植体和黏膜的混合支持方式,从而减缓牙槽嵴的吸收,其临床应用越来越广泛。本文从OVID和PUBMED数据库检索相关文献,与前一时段相比较并分析,对下颌种植覆盖义齿研究动态做一综述。