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.     

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.     

Are mu-opioid receptors involved in the control of endothelin-1 release from the pituitary gland in normal and dehydrated rats?

A stereognostic ability test was performed in 60 patients. Forty patients were rehabilitated by means of osseointegrated implants. One group consisted of 20 patients with fixed prostheses on implants in both the upper and lower jaws. The other 20 patients had a maxillary denture while in the mandible an overdenture was retained by means of two implants connected by a bar. They were compared to a group of 20 subjects (controls) with a non-restored natural dentition. For the stereognostic ability test, subjects had to recognise ten different test pieces by manipulating them with two antagonistic incisor teeth, avoiding any contact with other oral structures. Both response time and percentage accuracy of recognition were evaluated. The present findings indicated that subjects with an overdenture on implants did not score significantly different from those with an implant-supported fixed prosthesis. In contrast, subjects with teeth had a significantly better stereognostic ability. The percentage of correct responses was 52% for overdentures, 56% for fixed prostheses on implants and 75% for natural dentitions. From these results, it could be concluded that the stereognostic ability is impaired in subjects rehabilitated with osseointegrated implants by about one-third to one-quarter compared to subjects with natural teeth.     

Follow up and maintenance of implant supported prostheses: a comparison of 20 complete mandibular overdentures and 20 complete mandibular fixed cantilever prostheses

Two independently selected groups of 20 patients who were edentulous in te mandible, were followed up on a regular basis over a 5-year period following restoration with a lower implant stabilised prosthesis and conventional upper denture. Significantly more treatment was required by those who received complete mandibular overdentures than those provided with complete fixed mandibular prostheses. In addition to adjustment for the relief of denture trauma to the mucosa, more mechanical problems arose with overdenture implant prostheses.     

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.     

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.     

Treatment planning of the elderly implant patient

The prevalence of partial and complete edentulism in the older adult patient and the predictability of specific types of dental implants obligates the dental health professional to consider the fabrication of implant-related prostheses as an alternative treatment option. Special emphasis is placed in this article on the provision of clip-bat overdentures in the treatment of the fully edentulous patient and their relative advantages compared to a fixed-hybrid prosthesis.     

Patient satisfaction with dentures made by dentists and denturologists

BACKGROUND: Within Quebec and elsewhere in Canada, patients requiring removable prostheses consult either dentists or denturologists. In this article, we describe the socioeconomic characteristics of 410 edentulous individuals seeking replacement of their dentures, and compare the levels of satisfaction experienced by the patient groups provided with conventional dentures by dentists and by denturologists. METHODS: All subjects responded to announcements seeking participants in a clinical trial. The announcements indicated that all participants would receive new prostheses. Data were collected via telephone interviews. Sociodemographic variables included sex, age, education level and family income. Subjects were asked to evaluate their present maxillary and mandibular prostheses for general satisfaction, stability, comfort, ability to chew, ability to clean and appearance. Age, cost and the provider (dentist or denturologist) of the original prostheses were also recorded, and responses were then compared between the groups of subjects treated by dentists (N = 91) and denturologists (N = 319). RESULTS: There were no significant differences in the sociodemographic characteristics of the two groups, except for a small difference in mean age (two years). Both groups had paid approximately the same amount for their complete prostheses. As expected, most individuals were satisfied with their maxillary prostheses, but dissatisfied with their mandibular prostheses. Significantly more subjects in the denturologist treatment group than the dentist treatment group gave their mandibular prostheses a poor rating for general satisfaction (p = 0.003), comfort (p = 0.04) and stability (p = 0.016). CONCLUSIONS: These results suggest that the edentulous patients treated by dentists and denturologists share similar sociodemographic characteristics, and pay a similar cost for treatment. However, those treated by denturologists seem to be more dissatisfied with their mandibular prostheses than those treated by dentists.     

The cost of dental implants as compared to that of conventional strategies

The effectiveness of dental implants is widely studied, especially in terms of their clinical outcomes. However, from the policymaker's point of view, variables other than safety and efficacy, such as the costs and effectiveness of dental implants as compared to other treatment alternatives, are vital in decision making. This paper compares the costs of different treatment strategies in a randomized clinical trial in patients with resorbed mandibles and persistent problems with their conventional dentures: treatment with a mandibular overdenture on permucosal dental implants, an overdenture on a transmandibular implant, new dentures after preprosthetic surgery, and new dentures only. Data were gathered on an individual patient level to gain insight into specific cost episodes. Direct costs were subdivided into labor, material, technique, and overhead. Data concerning these components were gathered during the consecutive treatment phases in the first year. Results show that the resources used to treat a patient with an overdenture supported by a transmandibular implant are seven times those of a complete new set of dentures. Comparison of the cost ratio of an implant-retained overdenture supported by permucosal implants and conventional new prostheses proves less unfavorable: 1:3. New dentures after preprosthetic surgery are almost as expensive as treatment with permucosal implants.     

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.     

Aesthetic considerations for maxillary obturators retained by implants

Maxillary obturators are prostheses used to replace maxillary tissues, missing congenitally or removed by trauma or tumor ablative surgery. These prostheses are used to restore function (speech, swallowing, and mastication) and aesthetics. A considerable number of edentulous patients have difficulty in retaining this type of prosthesis. Utilization of osseointegrated dental implants is a significant adjunct in treating these cases, but it must be undertaken with careful planning to ensure predictable aesthetic results. The learning objective of this article is to discuss the technique of designing aesthetic maxillary prostheses supported by osseointegrated dental implants. The discussion includes indications and contraindications, and a postcarcinoma surgery case is used to illustrate the clinical procedure.     

A comparison of the effect of different occlusal forms in mandibular implant overdentures

STATEMENT OF PROBLEM: Posterior tooth form selection for implant overdentures is made according to personal preference and experience using the concepts of conventional complete denture prosthodontics. PURPOSE: This study (1) compared the masticatory efficiency of three occlusal forms, 0 degrees, 30 degrees, and lingual contact (lingualized occlusion), in subjects with mandibular implant overdentures, and (2) determined their effects on the implant supporting tissues. MATERIAL AND METHODS: Eight patients who had four root form implants in the mandibular symphysis area connected with a Hader bar were selected. Maxillary and mandibular dentures were constructed for each patient with interchangeable posterior segments and the three occlusal forms were tested. The masticatory efficiency for each posterior tooth form was assessed with objective food tests and a subjective patient preference questionnaire. Periodic evaluation of implant-supporting tissues also was performed. RESULTS: Reliability analysis showed that all R1 coefficients were > or =0.80 (<0.001), indicating high subject consistency between multiple chewing efficiency trials. MANOVA analysis indicated a significant difference in chewing efficiency among the three occlusal forms (p < 0.001). The 0 degree occlusal form was associated with a significantly higher number of chewing strokes compared with 30 degrees or lingualized occlusal forms. The different occlusal forms were not found to have a clinically detrimental effect on the peri-implant soft or hard tissues. CONCLUSION: Chewing efficiency tests and patient preference ratings showed that 30 degree teeth and lingual contact provided better chewing efficiency than 0 degree teeth. None of the tested occlusal forms showed any clinical or radiographic detrimental effect on the implant-supporting tissues.     

Human herpesvirus-6 infection in liver transplant recipients: documentation of pathogenicity

In the posterior partially edentulous jaw, implants may be used to supplement existing natural dentition. Frequently, the maxillary sinuses and the mandibular nerve preclude the fabrication of freestanding implant-retained prostheses. However, if an implant and a natural abutment are combined, a fixed prosthesis can be fabricated, restoring the arch into the premolar area. The histories of three patients with attachments connecting implant-retained ceramotitanium crowns with crowns on natural abutments are described. A design for a rigid custom-made attachment for the Br?nemark system, using standard components with a machine-duplication, spark-erosion technique, is suggested.     

Ten-year results for Br?nemark implants immediately loaded with fixed prostheses at implant placement

This investigation was initiated to develop a method to provide patients with a fixed provisional prosthesis placed at the time of implant placement. Sixty-three standard 3.75-mm Nobel Biocare implants of varying lengths were placed into mandibular sites in 10 patients and followed for up to 10 years. Twenty-eight implants were immediately loaded at implant placement, providing support for fixed provisional prostheses, while 35 adjacent implants were allowed to heal submerged and stress-free. Following a 3-month healing period, the submerged implants were exposed and definitive reconstruction was accomplished. All 10 prostheses supported by 28 implants placed into immediate function at the time of implant placement were successful during the 3-month healing period. Of these 28 implants placed into immediate function, 4 ultimately failed. Of the 35 submerged implants, all are osseointegrated and in function to date. Life-table analysis demonstrates an overall 10-year survival rate of 93.4% for all implants. The 10-year life-table analysis of survival is 84.7% for immediately loaded implants and 100% for submerged implants. Statistical analysis of the submerged versus immediately loaded implants demonstrates failure rates for immediately loaded implants to be significantly higher (P = .022 by the log rank test). These data demonstrate that although mandibular implants can be successfully placed into immediate function in the short term to support fixed provisional prostheses, long-term prognosis is guarded for those implants placed into immediate function distal to the incisor region.     

Load factor control for implants in the posterior partially edentulous segment

There are inherent biomechanical differences in the implant treatment of completely edentulous arches and posterior partially edentulous segments. The partial prosthesis does not benefit from cross-arch stabilization and is, therefore, more susceptible to bending loads. Because of the difference in mobility between teeth and implants, implants may carry a major share of load when mixed with teeth in the same quadrant. However, the frequency of implant overload in posterior partial restorations is low, and, with appropriate treatment planning, overload in these situations is almost always preventable. A checklist procedure is proposed to help the clinician enumerate and evaluate deleterious load factors. By screening patients for such factors in advance, the clinician may identify and avoid potential overload situations when conceiving and fabricating implant-supported posterior partial prostheses. A second checklist, for use at follow-up appointments, lists alarm factors that serve as an early warning of overload once the prosthesis is in place.     

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.     

Impairment, disability, and handicap in multiple sclerosis. A cross-sectional study in an incident cohort in M?re and Romsdal County, Norway

Non-submerged ITI Bonefit implants (ITI Dental Implant System) were inserted in edentulous lower jaws of 46 patients. The patients were provided with either a fixed prosthesis or an overdenture, and has been followed during a 2-year-period. At the 1-year examination, the suprastructures were removed permitting test of the individual implant stability. Radiographic examinations were performed in connection with the loading of the implants and at the 1-year examination. In total 216 implants were inserted. 4 implants were lost before loading and 4 during the 2nd year of function, which gives a survival rate after 1 year 98% and after 2 years of 96%. The mean marginal bone loss during the first year of function was 0.1 mm. However, the marginal bone changes had a high degree of variation and four implants showed a severe bone loss. The intention is to follow this patient group with annual examinations during 5 years.     

Fixation of facial and auricular prosthesis with osseous implants in cranial bone

OBJECTIVE: To evaluate the use of osseointegrated implants to fix facial and auricular prostheses. DESIGN: Retrospective. SETTING: University Hospital Groningen, the Netherlands. METHODS: Thirty patients were treated with Br?nemark implants for fixation of auricular (21 patients) and orbital (9 patients) prostheses during May 1988-December 1995. The complications during the procedure, the success rate of the implants, skin reactions around the implants and patient satisfaction were recorded. RESULTS: A total of 97 implants were placed. One implant had to be removed after the healing period because it was loose. No other implants were lost during the follow-up period (mean 36 months; range: 12-91). The skin around the implants sometimes showed a mild reaction which could be adequately treated. In most of the cases no inflammation of the skin was observed. Retention, ease of handling and wearing comfort of the facial prostheses were excellent. CONCLUSION: Fixation of facial and auricular prostheses can be improved by osseointegrated implants resulting in high patient satisfaction.     

Fabrication of a fixed partial denture in the Class II partial edentulous mandible using the UCLA abutment: a clinical report

Several methods are currently available to restore the partially edentulous patient with osseointegrated implants. The UCLA abutment eliminates the unesthetic, traditional transmucosal abutment and can provide esthetic crowns, fixed prostheses, and subgingival porcelain margins without the need for excessive instrumentation and components. A clinical report for the fabrication of a direct, implant-borne fixed prosthesis using the UCLA abutment is presented.     

The use of precision attachments in a lower full arch rehabilitation with osseointegrated implants--a clinical report

A technique for restoration of a case of Kennedy Class V edentulous span was described. This situation is a long edentulous span bounded anteriorly by a weak support and considered as one of the most difficult situations to restore. Two osseointegrated screw implants were inserted in the edentulous span. Together with remaining natural teeth supported a full arch restorations. Three precision attachments were included in the restoration to allow movement of the remaining teeth and to allow broken stresses at where the prosthesis extended along the corners of the mouth.