Implant-supported overdentures: the ZAAG attachment system

It has been amply demonstrated during the last decade that there are significant advantages to implant-supported overdentures beyond conventional complete dentures. Several attachment systems exist for connecting the overdenture to the implants, and practically all of them present notable benefits to the patients. This article discusses the use of the Zest Anchor Advanced Generation (ZAAG). This system, an outgrowth from the original Zest attachment, uses both individual implant attachments and bar attachments, and is compatible with all major implant systems. In addition to the retention, stability, and resiliency the ZAAG implant attachment system provides, it has the advantage of placing the resistance force of the attachment close to the implant body.     

Fixed temporization and bone-augmented ridge stabilization with transitional implants

Utilization of dental implants in full-mouth restorations is now a well-accepted treatment modality, with numerous modifications and implant systems documented in the literature. The efficacy of the treatment procedure generally requires an extended postplacement healing period prior to loading the implant fixture with the stress of mastication. Until recently, clinicians have not been able to address patient comfort requirements during the healing period. The teaching objective of this article is to present and evaluate a transitional implant system used to provide function during the healing phase. The system consists of thin titanium transitional implants and a three-component overdenture that is intended to absorb the pressure during function and protect the augmented implant site and the definitive implant fixtures from the stress of immediate loading. Treatment objectives for the transitional and definitive implants are made during the initial treatment planning. Three cases are presented to document and illustrate the clinical procedure.     

Anterior aesthetic considerations for the placement and restoration of nonsubmerged endosseous implants

Nonsubmerged endosseous dental implants should be considered when planning optimal anterior implant rehabilitation. Detailed diagnostic records are a necessity, along with preoperative and preprosthetic treatment plans that are designed to address the unique challenges of anterior restorations. This paper discusses these concerns and presents two case reports which utilize some of the techniques that can be incorporated into achieving predictable anterior aesthetic rehabilitation using a single-stage implant. The learning objective of this article is to familiarize the reader with those challenges and techniques.     

Implant-supported overdenture therapy: a retrospective study

All patients (n = 46) treated with implant-supported overdentures at the Department of Prosthetic Dentistry, Dental and Medical Health Centre, Halmstad, Sweden, from 1986 to 1993 were studied. The clinical examination was completed in 1994. The material was divided into two subgroups: Group A had been initially treatment planned for an implant-supported overdenture, and Group B had been planned for fixed prostheses but because of loss of implants before loading, treatment with a fixed prosthesis was not possible. The authors present their experience and patient reactions to overdenture therapy in two defined groups of patients. The implant failure rate before loading for Group A (n = 12) was 15% (six implants out of 39), and the rate before loading for Group B (n = 29) was 43.6% (68 implants out of 156). After prosthodontic treatment in Group A, the implant success rate after loading was 87.9%, and the overdenture stability was 84.6%. In group B, 17 implants placed in the maxillae were lost after overdenture therapy, which resulted in an implant success rate of 79.3%. A total of eight overdentures, all of which had been placed in the maxillae, were lost, resulting in an overdenture stability of 73.3%. In this study "change of retentive clips" was the predominant prosthodontic complication related to the overdentures, especially in Group B. Most of these complications (62%) occurred in patients with clinical signs of bruxism. Patient reactions to treatment with an overdenture were positive regarding esthetics for both groups. More negative views were recorded in Group B than in Group A in response to function and retention of the overdenture.     

A randomized clinical trial comparing the efficacy of mandibular implant-supported overdentures and conventional dentures in diabetic patients. Part I: Methodology and clinical outcomes

STATEMENT OF PROBLEM: Scientific evidence is lacking to support the general application of implant-supported mandibular overdentures. PURPOSE: This randomized clinical trial was undertaken to compare the efficacy of conventional mandibular and implant-supported overdentures in diabetic edentulous patients with clinically acceptable metabolic control. METHOD: A total of 102 diabetic patients, treated with or without insulin, were randomized to receive a new maxillary denture and either a conventional or an implant-supported removable mandibular overdenture. Treatment was completed for 89 patients, 37 with the conventional and 52 with implant-supported dentures. Detailed examinations, tests, and questionnaires were given before and at 6- and 24-months after treatment completion. Comparisons between the two treatment groups were made for treatment failures based on prespecifed criteria and the type and amount of maintenance care provided. RESULTS: The insulin and noninsulin treated groups were collapsed because of the lack of significant differences at entry. The conventional denture and implant-supported overdenture groups were similar in terms of general demographics, medical status, quality of their original dentures and denture support, several functional measures, and patient satisfaction. Treatment was judged to be successful in 56.9% of patients with conventional dentures and 72.1% with overdentures. This difference in success rate was not statistically significant (p > 0.05). Patients with treatment failures in both groups required excessive maintenance care. Those with conventional dentures needed frequent denture base adjustments and relines, whereas those with overdentures required frequent clip replacements and repairs. Although significant improvements were seen with both treatment modalities, a higher percentage of patients with implant-supported overdentures than those with conventional dentures reported improvements in chewing comfort and moderate-to-complete overall satisfaction.     

A within-subject comparison of mandibular long-bar and hybrid implant-supported prostheses: psychometric evaluation and patient preference

Although it has been shown that patients are more satisfied with prostheses supported by implants than with conventional dentures, there have been few direct comparisons of the various designs of implant-supported prostheses. This within-subject crossover clinical trial was designed to compare two forms of removable prostheses which are frequently prescribed for the edentulous mandible: a long-bar overdenture supported by 4 implants and a two-implant hybrid overdenture. Sixteen completely edentulous subjects were given a new maxillary conventional denture: Ten of them received the mandibular long-bar prosthesis first and six the hybrid. After a two-month adaptation period, psychometric measures of various aspects of the prostheses and physiological tests of masticatory efficiency were carried out over three weeks. The mandibular prostheses were then changed and the procedures repeated. At the end of the study, subjects were asked to choose the mandibular prosthesis that they wished to keep, and final psychometric measures were taken. In this paper, the results of the psychometric assessment and patient preference are presented. Subjects assessed factors such as general satisfaction, quality of life, stability, retention, comfort, esthetics, ease of cleaning, speaking, and chewing, and how well-chewed foods were before being swallowed. Most of the factors except ease of cleaning and speaking were rated significantly better with long-bar overdentures than with hybrid ones. These results are consistent with the fact that all subjects chose long-bar overdentures, reporting stability, ease of chewing, and comfort as the most important factors influencing their choice. These results suggest that, although subjects assign high ratings for most factors to hybrid overdentures, they find long-bar overdentures to be significantly more stable, comfortable, and easier for chewing.     

Acute liver failure

PURPOSE: This article reviews the literature on radiographic imaging techniques and image interpretation for dental implant treatment. MATERIALS AND METHODS: MEDLINE was used to identify published peer-reviewed literature for this report. RESULTS: Radiographic images are indispensable in the evaluation of osseous structures when planning treatment for dental implants. Potential bone sites for implant placement can be assessed clinically by means of palpation or probing through the mucosa; however, diagnostic imaging provides the best means for indirectly measuring bone dimensions. After healing of the implant site, the application of radiology is useful to verify the amount of bone adjacent to the implant and that the transmucosal abutments fit the implant. Upon completion of the implant prosthesis, radiology may be used to monitor initial and long-term success of implant treatment. CONCLUSION: Recommendations for the application of radiology over the course of treatment are made for various implant cases ranging from the overdenture to the single-tooth implant.     

Implant retained overdentures in mandibular reconstruction: a case report

This case report describes the clinical and laboratory procedures used in the rehabilitation of a patient treated for oral cancer with surgery and radiation therapy. During surgery, a large portion of the mandible was removed and reconstructed with a bone graft. Following therapy, the patient was left with poor esthetics and difficulties with mastication and speech. The goal of prosthodontic treatment was to improve esthetics and restore function. This was successfully achieved through the placement of dental implants and the construction of an implant retained overdenture. A bar was employed to split the implants together and an O-ring system was chosen for retention. The decision to use this type of prosthesis and attachment selection was based on the patient's dental history, esthetic demands, and the need for stress distribution.     

Study of mechanical properties of micromachined dental implants

Advancements in technologies and techniques within the dental industry have given rise to new and effective tooth replacement procedures for damages resulting from causes such as trauma or aging. While these treatments are widely available for patients, they remain highly expensive, preventing patients from much-needed dental care. The elevated cost of dental implants is in part associated with their components that are mainly available through third-party companies at a premium cost. To be cost effective, dental laboratories are exploring the option of producing their own dental implant components, and are therefore acquiring knowledge of manufacturing techniques and quality assurance expertise to produce quality components. In order to ensure high quality and reliability, the fabricated components must be tested and benchmarked against current implants on the market. The present study examines the micro machining process of dental implants, specifically for the abutments and screws, and its impact on the mechanical properties of the components. To achieve this, dental implant abutment and screw prototypes were fabricated, experimentally tested, and compared. The impact of different machining processes on the mechanical properties of the implants was comparatively determined and analysed. The fabricated implant testing results show coherent mechanical properties displayed by good hardness, and material microstructures similar to market components, indicating a high level of prototype quality.     

The dark side of dioxygen biochemistry

The aim of this study was to evaluate the clinical function and long-term prognosis of overdentures retained by a small number of implants in the maxilla and mandible using one of two different attachment systems. Included in the study were all patients referred to specialty clinics in J?nk?ping and Link?ping, Sweden, during the treatment period who needed an overdenture and could be provided with a minimum number of two bilaterally-placed implants. Excluded were patients with bone-grafted jaws, irradiated cancer patients, heavy bruxers, and patients who had lost a fixed prosthesis because of implant losses. The patients were randomly assigned to receive one retentive system, either a round 2-mm-diameter bar with clips or ball attachments (Nobel Biocare). Eighteen overdentures were placed in maxillae and 32 in mandibles, supported by a total of 115 Br?nemark implants. Of the implants placed, 86.1% were continuously osseointegrated. The cumulative implant survival rates after 7 years of loading were 75.4% in the maxillae and 100% in the mandibles. There was no difference in implant survival rate between the attachment systems. Patients with implant losses were characterized by severely resorbed maxillary ridges and inferior bone quality, together with unfavorable loading circumstances such as short implants combined with long leverages. Complications and prosthetic adjustments were mostly resolved early and easily.     

Altered patterns of DNA methylation on chromosomes from leukemia cell lines: identification of 5-methylcytosines by indirect immunodetection

The feasibility of implant treatment in patients after oral ablative tumor surgery has not yet been investigated with consideration of the requisite high periodontal standards. A report on this topic has to deal not only with implant survival but also with implant health, bone response, soft tissue health, failure pattern, time of failure, and ease of restoration. For the assessment of an implant system, an overview must be accomplished that takes into account the different restorations used and their interaction with the implant system that was used. This study presents the Bone-Lock implant system (Howmedica Leibinger GmbH, Freiburg, Germany) in a retrospective investigation after 5 years of follow-up with special emphasis on the prosthetic restorations used following resection of oral malignancies. From early in 1990 through June 1996, we inserted 210 dental endosteal Bone-Lock implants (58 patients) after oral tumor resectioning. Included in the study were 45 patients with 162 implants and prosthetic restorations that had been loaded for 1 year (dentures retained by telescopic or bar-clip or ball attachments, implant-supported prostheses, tooth-to-implant connected bridges). Regular follow-up consisted of evaluation of the Plaque Index (Silness and L?e) and of the Sulcus Bleeding Index (L?e), measurements of pocket probing depth, implant mobility (by means of the Periotest method), bone resorption (according to X-ray findings), and a questionnaire that registered patient satisfaction. The results were evaluated for each restoration and were compared with baseline standards. The overall 5-year survival rate was 83.2%. For implants that had been in place for over 365 days, the survival rate was 93%. The investigation showed that after resection of oral malignancies, patients could be treated with dental implants and superstructures with long-term efficacy similar to that found in healthy subjects considering internationally accepted standards. Implant treatment in tumor patients appeared to offer the most positive periodontic results when use of bar-clip or telescope-retained overdentures was involved. The patient satisfaction level with the described prosthodontic treatment was satisfactory.     

The pros and cons of laser dacryocystorhinostomy

Sixty-one patients participated in a longitudinal study designed to compare the psychological effects of osseointegrated implants with those of conventional denture replacements. Thirty-two patients who requested either relining or reconstruction of their dentures were asked to complete questionnaires designed to measure their psychological well-being while they were on a waiting list and then again 6 months after treatment. Their responses were compared with those of 29 patients who had received an osseointegrated implant. While the implant patients had reported significant declines in psychological distress, there was no such change for the denture patients. Although both groups experienced fewer disabling symptoms, the decline was greater for the implant group. Finally, neither group showed evidence of any change in self-esteem. The results suggest that osseointegrated implants can have a more positive effect on well-being than denture replacements.     

Functional endoscopic sinus surgery: preoperative assessment and postoperative evaluation

Long-term success of dental implants depends largely on the continued health of peri-implant hard and soft tissues and an appropriate force distribution on the implants. Since dental implants are accepted as viable and, in some cases, ideal restorative options, all members of the dental team are faced with the task of maintaining implant health. This review outlines the current understanding of implant health and disease and presents recommendations for the treatment and management of diseased implants.     

Clinical evaluations of a porous-surfaced endosseous implant system

Clinical evaluations of a new porous-surfaced implant concept (Endopore) in a large population of fully and partially edentulous patients are reported, and a technique of spreading buccal and lingual plates with osteotomes to place these implants in proximity to the sinus of the posterior maxilla is described. Three-dimensional, interconnecting pores on this implant's bone interface surface give a great surface area for bone engagement. When the maxilla is prepared by this spreading procedure, these implants can be successfully placed in areas having limited available bone. Our success rates are 97.0% for implants stabilizing a mandibular overdenture and 94.8% for implants placed in partially edentulous patients. Many times, sinus lift or other augmentation procedures can be avoided in the maxilla and mandible, allowing for less patient morbidity and for an implant reconstruction that is more affordable for the patient.     

An interactive, parallel, three-dimensional fast Fourier transform convolution dose calculation using a supercomputer

After cancer treatment in the head and neck area, mastication and speech are often affected. Some of the problems encountered can be solved by adequate dental rehabilitation. However, dental rehabilitation is often compromised for various reasons. The change in anatomy due to surgery often results in lack of denture-bearing mucosa. The effects of radiotherapy on the salivary glands and the mucosa result in dry oral tissue and diminished retention of removable dentures. Osseointegrated oral implants can help to solve these problems. Although implant treatment for patients with cancer of the head and neck is covered by the Dutch national health insurance, and there is therefore no financial obstacle, implants have not, so far, been widely used with these patients. In order to establish the possible reasons for this, an analysis was performed. Retrospective data on 95 consecutive patients were collected from records. The indication for the use of oral osseointegrated implants was reviewed. Analysis of the data showed that 45% did not need specific prosthetic rehabilitation. An indication for the use of osseointegrated implants was found in 25% of the patients. For various reasons, only 3% actually received implants. In striving to completely rehabilitate a cancer patient, the possible use of osseointegrated oral implants should be evaluated before the initial oncological treatment begins. The insertion of implants during the initial surgical procedure should be considered more often, with a view to reducing the number of surgical procedures.     

Affordable implant prosthetics using a screwless implant system

Many dentists have been reluctant to place dental implants because they have found that most implants are costly and time-consuming to place and have long-term maintenance problems. Most of these problems are caused by using screws to connect the abutment to the implant, the crown to the abutment or both. The use of a screwless implant system and conventional prosthetics, the author contends, can make implant dentistry affordable, versatile and easy to incorporate into all general dental practices.     

Practical implant dentistry--the mandibular removable overdenture prosthesis

The fully edentulous mandible presents functional, esthetic, and psychological challenges for the patient and the dentist. The mandibular overdenture supported by endosseous implants can provide a superior treatment modality, overcoming many of the difficulties inherent in the conventional denture. Advantages cited are increased denture retention, improved chewing efficiency, maintenance of bone height, replacement of lost anatomy, increased denture stability, reduction of soft tissue coverage and extension of the prosthesis, and easy access for hygiene maintenance. The major disadvantage rests with the patient's intolerance of a removable prosthetic design.     

Changes in chewing patterns after implantation in the edentulous mandible

Almost all edentulous patients with implant-supported prostheses in mandibles describe an improvement in their chewing function and quality of life. This was reason to believe that an implant prosthetic treatment actually influences mandibular border movements, as well as the chewing patterns. The present study compares border movements and chewing patterns in 15 patients recorded with the Sirognathograph. The first measurements were made with existing complete dentures. After implantation and rehabilitation with a Dolder-bar and clip-to-bar overdenture, the movements were recorded again. The measurements revealed an improved guidance of the mandibular movements and larger borderline patterns following stabilization of the complete denture with the bar. This leads to more harmonic shapes in the movements and better chewing efficiency.     

Cost-saving implant training aids

This article describes a simple step-by-step procedure that uses inexpensive materials to enable those who wish to learn procedures used in the construction of a screw-type implant overdenture to practice these procedures before they use expensive precious metal components. The use of this procedure will result in considerable savings in training costs and affords a greater opportunity to provide practical experience before making this type of an overdenture for patients. It could also provide for a rapid expansion in the number of trained personnel who could make this form of treatment available to a larger number of patients.     

The relationship of smoking on peri-implant tissue: a retrospective study

The term "peri-implantitis" is used to describe the formation of deep mucosal pockets around dental implants, inflammation of the peri-implant mucosa, and increased resorption of peri-implant bone. It has been speculated that when left untreated, peri-implantitis can result in implant failure. This retrospective study examines a possible correlation between smoking and the appearance of peri-implantitis. The clinical and radiographic observations of 366 implants in 107 patients who smoke were compared with those of a group of 1000 implants in 314 nonsmoking patients. Despite the retrospective nature of this study, a comparison between the two groups was possible. The mean follow-up period, mean patient age, implant locations, and percentages of fixed partial dentures and overdentures were consistent in both groups. There was no significant difference in the mean maxillary and mandibular hygienic indices between the group of smokers and that of nonsmokers. However, the group of smokers showed a higher score in the bleeding index, the mean peri-implant pocket depth, the degree of peri-implant mucosal inflammation, and radiographically discernible bone resorption mesial and distal to the implant. In the maxilla of the smoking group, these observations were significantly higher than both the mandibular observations for smokers and the maxillary observations of the group of nonsmokers (p < 0.01). No differences between the two groups were observed in the mandible. Aside from the systemic effects of tobacco smoking on the human organism, local cofactors seem to be responsible for the higher incidence of peri-implantitis in smokers and have a particularly negative effect on the maxilla. These findings confirm that smokers treated with dental implants have a greater risk of development of peri-implantitis.