SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Advantages of telescopic prostheses are in maintenance, repair, alteration, conversion, and offsetting problems of parallelism. A cemented telescopic implant prosthesis can be retrieved by incorporating a window or recess in the copings during the wax-up and using a flat-ended instrument for disengagement of the prosthesis.
When restoring the challenging maxillary arch, no one treatment will serve all patients optimally. An open mind must be maintained, and the prosthetic evolution and creativity will continue. The ideal tooth position for each case should be determined prior to surgery in order to ensure optimum prosthetic results. This presentation and paper discuss the restoration of the maxillary arch. Impressions, soft tissue model, bar pattern, alloy selection, screw seating, and screw-retained suprastructure over infrastructure are presented and illustrated.
The use of a screw-retained prosthesis on an osseointegrated implant is a popular treatment modality offering relative case in the removal of the restoration. One of the complications associated with this modality is the loosening of the abutment and coping screws. Loosening of the screws results in patient dissatisfaction, frustration to the dentist and, if left untreated, component fracture. There are several factors which contribute to the loosening of implant components which can be controlled by the restorative dentist and the lab technician. This article addresses the contributory factors and offers solutions which can be easily incorporated in the treatment.
Tissue integration of one-stage, nonsubmerged ITI implants over a 5-year period is documented. Fifty-four implants were placed in 38 partially edentulous patients. No implants had detectable mobility after a healing phase of at least 3 months, and there were no clinical signs of peri-implant infection. Radiographs revealed no peri-implant radiolucencies and all implants were in favorable positions for fixed prosthetic restorations. Following completion of the prosthetic treatment, all patients were placed in 3-month oral hygiene recall programs. Annual dental examinations included evaluation of each implant according to fixed criteria. Three years after implant placement, 51 of 53 implants (96.2%) were evaluated as successful (one patient was lost to the study). Acute peri-implant infections were associated with two implants; both were classified as late failures. The results demonstrated that one-stage transgingivally healing ITI implants integrate dependably in the tissue and that successful tissue integration can be maintained for at least 3 years.
Twenty-five adult patients with fully edentulous jaws, aged from 44 to 80 years were treated with seventy-one 3.5 mm diameter Astra Tech dental implants in the parasymphseal region. The length of these implants varied from 9 mm to 15 mm. Either two or three implants were inserted, subsequently exposed after a minimum period of 3 months, abutments and ball attachments placed. Full lower dentures incorporating gold alloy housings for ball-attachments were constructed. The average time that the implants were in situ was 4 years and 2 months, ranging from 1 year 3 months to 5 years and 7 months. Of the 71 implants placed, 67 achieved osseointegration-a success rate of 94%. The main complication was that of the ball-attachments becoming loose.
External hexagonal implants of known dimensions were assembled with premachined cast abutments and rebroached cast abutments. The abutment screws were tightened to 20 Ncm and 30 Ncm, and the samples were loaded off axis with 133.3 N. Load application was at 1,150 cycles per minute with a sample counterclockwise rotation of 28 cycles per minute. The premachined cast abutments tightened to 20 Ncm failed with a mean of 357,162 cycles (SD = 77,981 cycles). The rebroached cast abutments were cycled to 1 million cycles without failure. At 30 Ncm, the premachined cast abutments failed at a mean of 5.0 million cycles (SD = 2.2 X 10(6) cycles). Two of five rebroached cast abutments failed at 4.3 million and 9.5 million cycles, but the remaining samples showed no evidence of screw loosening after 10 million cycles, at which time the test was terminated. The results indicate a direct correlation between rotational misfit and screw loosening. Screw joints can be made more resistive to screw loosening by the elimination of rotational misfit.
A proposed protocol and differentiated success criteria for long-term evaluation of oral implants are presented. The protocol and criteria were applied to a retrospective patient material treated during a 1-year period and followed for 5 years. The protocol comprised a two-stage analysis of the collected clinical data. First, a quantitative analysis of the outcome was made using a life table. Based on the information obtained during the follow-up, each implant was categorized into one of three groups: unaccounted for, failure, or survival. A qualitative analysis of the survival group was then performed by active testing against defined criteria. Depending on the modes of clinical and radiographic examinations and their results, surviving implants were either further assigned to one of three success grades or remained in the survival group. The data are presented in a four-field table at one level of success. Strict success criteria together with individual stability testing and radiographic examination of each consecutive implant should be used when a new implant system is evaluated or when a new application is explored. Radiography alone and more moderate success criteria may be used to document routine treatments, provided that an already well-documented implant system is studied.
The prosthodontic methods and outcomes of treating 127 patients in nine centres over a period of 5 years is described. The benefits perceived by patients and the changes induced in the denture-bearing tissues and temporomandibular joints are reported. To sustain effective treatment outcomes, the levels of maintenance needed by the overdentures are contrasted for restoration of the edentulous mandibles and maxillae.
Eight partially irradiated oral cancer patients were treated using either mandibular implant and mucosa-supported telescopic coping prostheses or a restoration that was completely implant-supported with telescopic copings. Both types of restorations provided sufficient positional stability and peri-implant hygiene, and functional and esthetic improvement. However, only the completely implant-supported telescopic prosthesis avoided soft tissue ulcers that had the potential for the development of osteoradionecrosis. This type of restoration can especially be recommended for irradiated patients.
This study used three-dimensional finite element analysis to investigate the effect of three different occlusal surface materials (resin, resin composite, and porcelain) and four different framework materials (gold, silver-palladium, cobalt-chromium, titanium alloys) on the stress distribution in a six-implant-supported mandibular fixed prosthesis and surrounding bone. A total of 172 N vertical load was distributed over the entire occlusal surface of the finite element model. Generated stress values were calculated in the occlusal surface material, framework, prosthesis retaining screws, implants, and surrounding cortical and spongy bones. The results obtained demonstrated that using a prosthesis superstructure material with a lower elastic modulus (1) did not lead to substantial differences in stress patterns nor in values at the cortical and spongy bones surrounding the implants; and (2) concentrated stresses in the retaining screws for the prosthesis and thus increased the potential risk of prosthesis failure. For the single loading condition investigated, the optimal combination of materials was found to be cobalt-chromium for the framework and porcelain for the occlusal surface.
Explore the source record for details and available documents.
This investigation was concerned with the resorption of the posterior mandibular residual ridge in patients wearing mandibular overdentures supported by either parallel-sided bars (rigid joint) or oval straight bars (resilient joint) on two activated implants. Rotational tomographs were taken shortly after implant placement and up to 8 years later. Using proportional measurement, the area of residual ridge was measured in bilateral posterior areas. Patients rehabilitated with implant-stabilized mandibular overdentures demonstrated posterior mandibular residual ridge resorption at low rates, which were not significantly influenced by the design of the prefabricated bar.
Explore the source record for details and available documents.
Correct placement of implants is facilitated by the parameters that are already established, dictated by the struts and borders of the existing implant frame. The root-form implants should be: Contained in the anterior symphysis of the mandible. Completely encompassed in bone, without any contact with the Vitallium frame. As long as possible, to enhance biomechanical support of the superimposed bar and prosthesis. Evenly dispersed, in order to support a Hader bar. Independent of the previous implant system. Placed to fill the anteroposterior spread as completely as possible. The rationale and approach should comprise these requirements in order to achieve a predictable solution to mechanical failure of a subperiosteal implant, in an efficient manner, with the least possible trauma to the patient.
The advances in osseointegration have resulted in an increased utilization of implants for restoration of the edentulous jaw. The success of osseointegrated implants supporting full arch prostheses has become more predictable. All implant restorations require a thorough diagnosis and a definitive treatment plan. Following a diagnostic wax-up, an optimal surgical implant template must be fabricated; it serves as a guide or prescription for placement of implants in an optimal anatomic location. The slightest misangulation of an implant may create restorative limitations. In such circumstances, alteration of the restorative design or selection of alternate materials may be required. The learning objective of this article is to review the fabrication of a combined ceramometal and resin-metal fixed/removable implant-supported mandibular hybrid prosthesis. Diagnosis, surgical template fabrication, vertical dimensions, buccal/lingual space limitations, and aesthetics are discussed.
Explore the source record for details and available documents.
This retrospective study investigated the outcome of 73 telescopic implant-supported fixed prostheses. Fifty-four prostheses were entirely cement-retained, and 19 incorporated a screw-clamping unit. The rate of complications was low and in most cases minor in nature. Cement-retained prostheses involving a distal cantilevered extension required the greatest postoperative maintenance. Despite the small number of combined screw- and cement-retained prostheses, the lack of complications and ease of retrievability make this approach worthy of further study.
Transmission of masticatory load in mandibular implant-retained overdentures was evaluated using a three-dimensional finite element model. The reaction forces on the distal edentulous mucosa and the stress on the perimplant bone were compared in overdentures retained either by two ball attachments or by two clips on a bar connecting two implants. In the finite element model, a 35 N load on the first mandibular molar induced a greater reaction force on the distal edentulous ridge mucosa of the nonworking side when the overdenture was anchored by ball attachments than with the clips/bar attachment. Stress on peri-implant bone was greater with the clips/bar attachment than with the ball attachment.