Masticatory function with mandibular implant-supported overdentures fitted with different attachment types

Oral Rehabilitation by means of implant-retained mandibular overdentures is known to improve the oral function. The improvement may depend on the degree of retention and stability of the denture and thus on the type of attachment. In this within-patient cross-over clinical trial, we examined the hypothesis that more retention and stability of the overdenture improves the masticatory function. Eighteen patients received two permucosal implants, a new overdenture, and, successively, three different suprastructure modalities: a magnet, a ball, and a bar-clip attachment. We quantified aspects of the oral function by measuring the electromyographic activity of the jaw muscles and the jaw movement during chewing. The muscle activity was significantly lower for the unsupported new mandibular denture compared with values for the supported new denture. No significant differences in muscle activity were observed among the three attachment types. Furthermore, we did not observe significant differences in jaw muscle activity between the old unsupported denture and the new supported denture, despite significant differences in masticatory performance. Measuring muscle activity during chewing will thus not provide adequate information about masticatory function. Thus, subjects chewed more efficiently after implant treatment. No changes in cycle duration or in jaw movement parameters were observed among the various measurement moments.     

Masticatory function and patient satisfaction with implant-supported mandibular overdentures: a prospective 5-year study

PURPOSE: The aim of this study was to assess the outcome of treatment with implant-supported mandibular overdentures in terms of biting and chewing, in entirely satisfied and not fully satisfied patients. MATERIALS AND METHODS: Twelve edentulous patients who had worn dentures for at least 5 years participated. They were in good health but had retention problems with their mandibular dentures. First, all patients received new dentures. After 3 months, two Astra Tech implants were placed in the anterior part of the mandible, and 6 months later the abutments were connected. Patient assessment (questionnaire) and functional recordings (chewing ability, bite force, electromyographic activity) were performed with the new dentures, and again 3 months, 1 year, and 5 years after overdenture treatment. RESULTS: After treatment, all patients were able to comminute hard and tough food, the maximum bite force and the chewing activity increased in parallel, and the duration of the chewing cycle was reduced. Every patient felt improved function and reduction of chewing pain. However, the seven patients not fully satisfied with the function of the implant-supported mandibular overdentures were characterized by lower muscle activity, even before implant placement, than the entirely satisfied patients. CONCLUSION: Implant-supported mandibular overdenture treatment permits better biting and chewing function than conventional complete dentures.     

Masticatory performance with mandibular implant-retained overdentures

It was investigated in a clinical trial whether the masticatory performance of complete-denture wearers depended on the support for their mandibular dentures by implants or mucosa. The trial involved the provision of a new maxillary denture and either a new conventional mandibular denture (mucosa-borne), a mandibular overdenture retained by two IMZ-implants (implant-mucosa-borne), or a mandibular overdenture on a transmandibular implant (TMI; mainly implant-borne). In comparison with mandibular implant-retained overdentures, subjects with conventional dentures needed 1.5 to 3.6 times more chewing strokes for an equivalent reduction in particle size. No differences in masticatory performance were found between subjects with IMZ-implants and those with TMI. This suggests that the increased stability of the mandibular denture with implants determines the wearer's masticatory performance, rather than the support by implants.     

Masticatory performance and mandibular movement patterns of patients with natural dentitions, complete dentures, and implant-supported overdentures

The aim of this study was to compare quantitatively the masticatory performance of patients with overdentures supported by two implants, conventional complete dentures, and natural dentitions. Each patient was asked to chew a gelatin cube. The collected remains of the test food (gelatine cube) were fractioned by a sieving procedure and weighed. Maximum mouth opening and masticatory area were measured using kinesiography. There were statistically significant differences among groups with respect to masticatory performance using a 3.15-mm-diameter sieve (P < .001) and 0.5-mm-diameter sieve (P < .001), masticatory area (P = .019), and maximum mouth opening (P < .001). Increasing retention of a mandibular complete denture with two implants improved masticatory performance.     

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.     

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.     

Treatment planning: implant-supported partial overdentures

When multiple anterior teeth are missing, many options of replacement are available. Traditionally, the choice was between a fixed or removable prostheses. Today, with the predictability of dental implants, the options of tooth replacement range from removable partial dentures to implant-supported fixed prostheses. The choice of which restoration that will best provide occlusion and esthetics depends on multiple factors including the number and location of missing teeth, the residual ridge form in relation to the replacement teeth, the relationship of the maxillary and mandibular anterior teeth, the condition of teeth adjacent to the edentulous span, the amount of bone available for implant placement, the patients "smile line" and display of teeth, lip support, and financial constraints. When there is minimal loss of the ridge contour, restorations that emerge from the ridge are the most functional and esthetic restorations, adhesive-type fixed partial dentures, conventional fixed partial dentures, and implant-supported restorations can be indicated with the choice of restoration dependent on a risk benefit and cost benefit analysis. When there is a loss of ridge contour due to residual ridge resorption or trauma, the decision becomes more complex as not only does the tooth structure need to be replaced, the ridge form also has to be replaced. (Figures 1 and 2). This can be assessed clinically as illustrated by Figures 1 and 2 where a dis crepancy in arch form and ridge form in relation to the adjacent teeth and/or opposing arch can be observed. Other considerations are lip support and display of the teeth when smiling. This article presents a case and rationale for implant-supported par tial overdentures. Many authors have written on the merits of com plete overdentures. The complete overdenture has proven to be an improvement over conventional complete prostheses with respect to chewing efficiency, patient comfort and satisfaction. In partial edentulism, the implant-supported overdenture has several advantages, some in common with a removable partial denture.     

Masticatory performance and chewing experience with implant-retained mandibular overdentures

The relationship between masticatory performance and chewing experience has not yet been explored for patients with implant-retained overdentures. Although many relationships have been found between parameters of objective and subjective oral function, the structure of these relationships remain unclear. Therefore, we studied in a randomized clinical trial the relationship between the comminution of an artificial test food, i.e. masticatory performance, and the subjective chewing experience. The trial involved a comparison between two groups receiving implant treatment and one group receiving conventional complete dentures (CD). The implant treatment involved either a mainly implant-supported mandibular overdenture on a transmandibular implant (TMI) or an implant-tissue-supported mandibular overdenture on two IMZ implants (IMZ). Masticatory performance as well as chewing experience were substantially better for the implant-retained overdentures compared with the complete denture group. No significant differences emerged between the TMI and the IMZ group. A multiple regression analysis did not provide any comprehensibility in the relationship between masticatory performance and the variables of chewing experience. In the linear structural relation analysis (LISREL) no direct relationship was found between masticatory performance and functional complaints mandibular denture. The results show that an improvement in masticatory performance does not imply the same improvement in chewing experience and vice versa.     

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.     

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。     

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.     

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.     

Rehabilitation of geriatric hemiglossectomy patient with implant-supported overdentures. Clinical report

Carcinomas of the tongue constitute approximately 5% to 10% of oral carcinomas. Rehabilitation of these patients postsurgery is challenging because the motor control of the tongue is lost and postsurgical scarring reduces the vestibular depth needed to support and retain a denture. Implant-supported overdentures are a viable option to rehabilitate such patients. The restoration provides enhanced function and wearer comfort.     

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.