Research directions in implant prosthodontics.
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This article describes a new technique for fabricating cement-retained implant-supported prostheses. The technique involves cementation of the prostheses over customized gold cylinders. Access channels are incorporated in the prostheses to allow future access of the gold screws. This technique can be used in various clinical situations to achieve total passive fit of the framework without compromising retrievability. The technique overcomes the problems encountered with other previously advocated methods for constructing such prostheses. In addition, maintenance of the resulting prostheses is uncomplicated.
OBJECTIVE: To evaluate the clinical outcomes, and a possible correlation between peri-implant mucosal inflammation and marginal bone loss, 1 year after restoration in a group of Chinese patients with dental implants. METHODS: Observation of the clinical and radiographic parameters of 108 IMZ and Frialit-2 dental implants in 70 patients. RESULTS: One year after loading, there were no signs of mobility and peri-implant radiolucency in any of the implants. The average bone loss adjacent to implants was 0.63 mm (SD 0.78). The prevalence of peri-implant mucosal inflammation, as indicated by sulcus bleeding index (SBI) of 1.0 or more, was 32.9%. Significant positive correlation was found between mucosal inflammation and bone loss (P < 0.05). 92% of the observed sites had plaque index (PLI) scores greater than 1. CONCLUSIONS: The 1-year outcomes from this patient group indicate that IMZ and Frialit-2 implants provide satisfactory clinical results. One of the etiologic factors of alveolar bone loss around implants seems to be plaque-associated marginal inflammation. Improvement of oral hygiene, elimination of soft tissue inflammation, and proper treatment of periodontal disease of natural teeth are critical for maintaining the implants.
Many practitioners have found implant procedures to be too difficult or too much trouble to perform. Now that restorative components for most implant systems allow for cemented restorations, implant procedures for most clinical situations can be completed in two or three one-hour appointments. This article will review an easy-to-follow restorative philosophy using single- and two-to-three-unit implant restorative procedures that are similar to conventional dental procedures.
The fit of implant supported fixed prostheses is said to be of clinical concern because of the rigid fixation of an oral implant in its surrounding bone. The influence of the torque sequence of the set screws during fixation of implant supported fixed full prostheses on the final pre-load was investigated in vitro. No significant effect of the torque sequence of the set screws on the final pre-load was observed. The main objective of this study was to quantify and qualify the pre-load in vivo on implants supporting a fixed full prosthesis. This was performed when the prostheses were supported by all five or six implants and was repeated when the prostheses were supported by only four and three implants. A total of 13 patients with a fixed full implant supported prosthesis were selected. The existing abutments were changed for strain gauged abutments. After tightening the set screws with a torque of 10 N cm, the pre-load conditions were registered. The average (SEM) axial forces and bending moments in case of five or six, four and three supporting implants were 323 N (43 N), 346 N (59 N), 307 N (60 N) 21 N cm (3 N cm) and 21 N cm (2 N cm), 23 N cm (5 N cm), respectively. In addition, the pre-load was registered after fixation of a machined gold cylinder, as delivered by the manufacturer, on each of the supporting implants, representing the 'optimal fit' situation. The corresponding average (SEM) axial forces and bending moments in case of five or six, four and three supporting implants were 426 N (36 N), 405 N (40 N), 413 N (46 N) and 8 N cm (1 N cm), 8 N cm (1 N cm), 8 N cm (1 N cm), respectively. The induced axial forces after tightening the prostheses were significantly lower then after tightening the gold cylinder in case of five or six supporting implants (P < 0.02). The induced bending moments after tightening the prostheses were statistically significantly higher (P < 0.0001) then after tightening the gold cylinder in all test conditions (five or six, four or three supporting implants). This study underlines the static load present after screw tightening implant supported fixed full prostheses.
PURPOSE: The purpose of this report is to describe a new technique to fabricate and deliver an implant-supported fixed prosthesis to the patient on the day of surgery, and to propose a protocol for the prosthodontic and dental laboratory procedures. MATERIALS AND METHODS: The development of the Brånemark Novum prosthodontic protocol is reviewed, and clinical and dental laboratory assessments and methods are described. RESULTS: The total treatment time to fabricate a permanent implant-supported fixed prosthesis in the mandible can be reduced to 1 day with the Brånemark Novum technique. The new method includes a precise surgical technique using drilling templates for predetermined implant positions, a rigid splinting of the implants immediately after placement, the use of a prefabricated titanium framework, and elimination of implant impression procedures. CONCLUSION: With the technique described in this report, it is possible to provide patients with a permanent implant-supported fixed prosthesis in the mandible on the day of implant surgery. Patient benefits are obvious, with drastically reduced total treatment time, lower cost, and fewer clinical visits.
PURPOSE: The purpose of this retrospective multicenter study on implants combined with natural teeth was to investigate the implant survival rate and loss of marginal bone, as well as indications and complications pertinent to this form of implant therapy. MATERIALS AND METHODS: The study comprised 185 implants in 111 patients from six different clinics in Sweden. Gathering of data, which were taken from patient records, followed a strict protocol. The registrations included indications for treatment, failure of implants, radiographs from baseline and follow-up, and information on complications. RESULTS: The cumulative implant survival was found to be 95.4% (standard error 4.5%) up to 3 years of follow-up. The marginal bone level at baseline was lower in the maxilla compared with the mandible (P = .015), but any further loss did not differ between the jaws. The most severe complication other than loss of osseointegration (6/185) or periimplant infections (4/183) was intrusion of the abutment teeth, which occurred in 5% of the cases. In all instances, the intrusion was seen in constructions with nonrigid forms of connection between the implants and teeth. CONCLUSION: The tooth-implant supported prosthesis using the Brånemark system is in the short term an equally predictable treatment as the completely implant-supported prosthesis concerning implant survival and loss of marginal bone. When combining implants and teeth, a rigid form of connection should be used to prevent tooth intrusion.
PURPOSE: The aim of this retrospective study was to present the results of implant-supported telescopic prostheses in the mandible after removal of malignant tumors. MATERIALS AND METHODS: Between 1991 and 2000, 24 patients with squamous cell carcinoma (16 irradiated, eight nonirradiated) underwent mandibular rehabilitation with implant-supported telescopic prostheses. A total of 111 dental implants were placed. Treatment complications were observed. The cumulative survival rates of the implants and prostheses were evaluated by lifetable analysis. RESULTS: Within a mean follow-up period of 30 months (1 to 108 months), only three implants failed. All other implants are still in function. Of 24 patients, 23 were satisfied with their implant-supported telescopic restorations. Soft tissue, implant, or prosthetic complications occurred very rarely. The cumulative implant survival rate was about 97% and the cumulative prosthesis survival rate was about 95% at 9 years. CONCLUSION: Implants and implant-supported telescopic maxillofacial prostheses can successfully remain in function over a long period. Increased implant and prosthetic complications should not be expected. Therefore, telescopic implant attachments seem to be very useful as a treatment option for prosthetic restoration of the mandible in tumor patients.
High implant survival rates are published with more than 15 years of observation time. Failures over time are often caused by ongoing marginal bone loss. Therefore, the need for reliable monitoring of the stability of periimplant attachment and/or bone level is extremely important. Marginal bone loss around osseointegrated implants has often been associated with periimplantitis, but clinical observations cannot prove this relationship. Otherwise, the impact of excessive loading on periimplant bone has been shown in animal studies and has been positively related to implant failure in terms of implant mobility and marginal bone loss. Some clinical observations support this hypothesis.
This multi-centre study evaluated the performance of the Osseotite implant in the mandibular arch. Osseotite implants (n = 688) were placed in 172 patients; 43.5% were placed in the anterior mandible and 66.5% in the posterior mandible. Fifteen per cent of the implants were placed in soft bone, 56.9% in normal bone and 28.1% in dense bone. During placement, 49.9% of the implants were identified as having a tight fit, 48.6% a firm fit and 1.5% a loose fit. About one-third of the implants (32.4%) were short (10 mm in length or less). After 36 months, only 5 implants had been lost, for a cumulative survival rate of 99.3%. The 3-year results of this study indicate a high degree of predictability with placement of Osseotite implants in the mandibular arch.
The goal of this study was to provide data relative to the use of a new implant system (Mac System, Cabon, Milan, Italy) with a Morse taper implant-abutment connection for single implant restorations. The implant system is composed of an endosseous screw made of commercially pure titanium grade 2, while the abutment is titanium alloy (Ti-6Al-4V). A total of 80 single implants were placed in 69 patients (36 women and 33 men, mean age 42 years, range 16 to 61). All patients gave their informed consent and received a thorough clinical and radiographic examination. Smokers and diabetics were excluded from the study. Three implants were placed in areas of previous tooth impaction, 5 were placed in posttraumatic edentulous areas, 2 were used in situations involving tooth agenesis, and 60 replaced teeth lost because of caries or periodontal disease. All patients were edentulous for at least 1 year prior to treatment. The implants received a definitive prosthesis and had been in function for a mean period of 3.5 years. At second-stage surgery, 2 implants were removed because of lack of osseointegration. After 2 years of loading, 1 implant showed evidence of peri-implantitis and was removed. In addition, 2 fractured abutments and 1 loosened abutment were observed. Few mechanical or infectious complications were seen, and this may have been the result of high stability of the conical connection.
Between February 1995 and May 1996, 71 patients received treatment that involved 1 or more wide Screw-Vent implants. A total of 131 wide implants were placed. All patients were recalled 1 year after loading. Seven patients (14 implants) were lost to follow-up. Six implants were removed before completion of prosthetic treatment. One hundred eleven implants were evaluated at the recall examination. Almost all implants (109) supported a fixed prosthesis; in the majority of patients (93 implants), it was a fixed partial prosthesis. The mean loading time was 17 months (range, 11 to 21 months). No implants were lost during the loading period. The overall survival rate was 95%. The survival rate for mandibular implants was 94%; for maxillary implants, it was 96%. These percentages were not statistically different. Crestal bone remodeling was examined using periapical radiographs. After 17 months in function, only 3 implants (2.5%) presented bone loss beyond the first thread.
The purpose of this study was to evaluate the clinical success of immediate functional loading of immediate implants in edentulous arches. Five maxillary and five mandibular jaws were treated, and a total of 91 implants were placed; 66 of these implants were placed immediately after tooth extraction, and 25 were placed in healed sites. No bone substitutes or barrier membranes were used. Within 24 hours, fixed temporary restorations were inserted in all cases. During the entire 6-month healing time, all fixed temporary restorations were in normal function, after which the final fixed implant-supported restorations were inserted. After 24 months, the overall success rate of the implants was 92.31% (87.50% for the maxillary implants and 97.26% for the mandibular implants). The bone level measured mesially and distally was in 93.40% of all cases between the implant shoulder and the first thread. The present study shows that the immediate functional loading of immediate implants without the use of any bone substitutes or barrier membranes for fixed complete-arch reconstructions can be successful over a 2-year period.
PURPOSE: Anterior maxillary alveolar vertical distractions were followed for a 5-year period of time. MATERIALS AND METHODS: A total of 30 vertical distractions were done in 28 patients. Two patients had both anterior maxilla and anterior mandibular distractions for a total of 30 distractions. Two distraction techniques were used: an implant device (3i) and an orthodontic screw device (Osteomed) for orthodontic attachment. Both devices enabled some horizontal as well as vertical movement. The average net vertical distraction was 6.5 mm, but the average anterior horizontal movement was less than 2 mm. RESULTS: Eighty-four implants were placed, but 8 implants failed to integrate. DISCUSSION: All failed implants had been placed in poor quality bone that needed bone grafting. The most common restoration was a fixed prosthesis supported by implants; the longest follow-up post loading was 4.4 years. CONCLUSION: This clinical study gives additional evidence in favor of the stability and utility of vertical distraction procedures in the maxillary esthetic alveolar zone.
OBJECTIVE: This paper reports on the long-term outcome of patients with Kennedy Class IV partial edentulism treated in the Implant Prosthodontic Unit (IPU) at the University of Toronto, Toronto, Ontario. METHODS: The information for this paper was gathered from the charts of the first 30 consecutive, partially edentulous patients treated at the IPU. These patients all had Class IV edentulism and formed part of the original prospective clinical studies that were initiated in 1983. The patients' dental history suggested maladaptive experiences with traditional removable prostheses or a reluctance to have intact or quasi-intact teeth prepared as retainers for fixed prostheses. Fifteen men and 15 women treated with 94 Br nemark dental implants, supporting 34 prostheses, were followed until June 2000 (25 patients) or until they were lost to follow-up (5 patients). The multiple missing teeth occurred in 19 maxillae and 15 mandibles. RESULTS: The original prosthodontic treatments were intended to result in 33 fixed partial prostheses and 1 overdenture. At the time of this report, 25 patients with 86 implants supporting 31 fixed prostheses and 3 overdentures had been followed for an average of 12 years (range 7 16 years). The overall survival of implants was 92%. The difference between men (94%) and women (89%) was not statistically significant. CONCLUSIONS: This report is an interim update on an ongoing long-term prospective study. The results so far demonstrate a high survival rate for Br nemark implants supporting tissue-integrated prostheses for the management of anterior partial edentulism.
OBJECTIVE: Because osseointegration has been successful in the management of completely edentulous patients, it is tempting to extrapolate these results and infer the success of single-tooth replacement. Yet there are major clinical differences between edentulous and partially edentulous patients. This prospective study is a follow-up to one started at the University of Toronto in 1986. The purpose of this study was to continue longitudinal assessment of implant-supported single-tooth replacements. METHODS: The original study comprised 42 consecutively treated patients with a total of 49 implants. The patient group consisted of all University of Toronto patients treated with single Br nemark implants whose treatment had been completed more than 5 years previously (i.e., before 1994). No exclusion criteria applied. One implant was not osseointegrated at the time of stage 2 surgery, and 6 patients with reportedly successful osseointegrated implants were not available for recall. For the preparation of this report, 30 of the remaining 42 implants were assessed during recall examinations. Assessment of success was based on published criteria. In addition, soft-tissue appearance, implant immobility, occlusal contacts in centric occlusion and excursions, proximal contacts, tightness of crown and abutment screws, and patients' responses on satisfaction questionnaires were evaluated. RESULTS: The criteria defining success of treatment in implant prosthodontics were met by all 30 of the single-tooth implants, which had been in place for 5 or more years. Each implant was immobile, and each had a mean vertical bone reduction of less than 0.2 mm annually. CONCLUSION: Stable long-term results can be achieved with single Brånemark implant-supported crowns.
OBJECTIVE: This paper reports on the long-term outcome of implant-supported posterior-zone prostheses in the first 35 consecutive, partially edentulous patients treated in the Implant Prosthodontic Unit (IPU) at the University of Toronto, Toronto, Ontario. METHODS: A total of 106 Brånemark dental implants were placed in 46 posterior edentulous spans in 35 patients for the management of multiple missing teeth; the patients were followed prospectively. Treatment planning principles involved a minimum of 2 or 3 implants at each edentulous site and scrupulous occlusal prosthodontic designs. RESULTS: The overall survival of posterior implants was 94%. No factors in the patients' history adversely affected implant survival. CONCLUSIONS: This clinical update suggests that the use of Brånemark implants in the rehabilitation of patients who are partially edentulous in the posterior zone is highly effective and that survival of the implants is excellent.
PURPOSE: The effect of two levels of prosthesis misfit on prosthetic screw stability was evaluated. MATERIALS AND METHODS: Two levels of vertical discrepancies--100 and 175 microns--were introduced between an implant-supported complete denture and the terminal abutment. An implant-supported complete denture without vertical discrepancy served as a control. Cyclic load was delivered vertically on the cantilever portion of the prosthesis next to the terminal abutment for 48 hours for each trial. A total of seven sets of new screws were tested for each level of fit. RESULTS: The results revealed significant prosthetic screw instability at both the 100- and 175-micron levels of discrepancy. CONCLUSION: Vertical discrepancies of 100 and 175 microns introduced between an implant-supported fixed complete denture and the terminal abutment resulted in significant prosthetic screw instability.