Biomedical subjects

T Jemt

Publications and source records attributed to T Jemt.

90 records · Page 5Linked to original sources

PubMedDate not supplied

Clinical experiences with laser-welded titanium frameworks supported by implants in the edentulous mandible: a 5-year follow-up study.

PURPOSE: The purpose of this study was to report the 5-year clinical performance of implant-supported prostheses with laser-welded titanium frameworks and to compare their performance with that of prostheses provided with conventional cast frameworks. MATERIALS AND METHODS: On a routine basis, a consecutive group of 824 edentulous patients were provided with fixed prostheses supported by implants in the edentulous mandible. In addition to conventional gold-alloy castings, patients were at random provided with 2 kinds of laser-welded titanium frameworks. In all, 155 patients were included in the 2 titanium framework groups. A control group of 53 randomly selected patients with conventional gold-alloy castings was used for comparison. Clinical and radiographic 5-year data was collected for the 3 groups. RESULTS: All followed patients still had fixed prostheses in the mandible after 5 years. The overall cumulative success rates were 95.9% and 99.7% for titanium-framework prostheses and implants, respectively. The corresponding success rates for the control group were 100% and 99.6%, respectively. Bone loss was 0.5 mm on average during the 5-year follow-up period. The most common complications for titanium frameworks were resin or tooth fractures, gingival inflammation, and fractures of the metal frames (10%). One of the cast frameworks fractured and was resoldered. Loose and fractured implant screw components were few (< 1%). CONCLUSION: Even though the cast frameworks had a higher success rate, the overall titanium framework treatment result was well in accordance with the result of the control group. The test groups performed better after clinicians had gained some experience with the technique, and laser-welded titanium frameworks seem to be a viable alternative to conventional castings in the edentulous mandible.

Adult↗

PubMedDate not supplied

Precision of CNC-milled titanium frameworks for implant treatment in the edentulous jaw.

PURPOSE: The purpose of this report was to describe a new technique to fabricate one-piece, implant-supported titanium frameworks by means of a computer numeric-controlled (CNC) milling technique, and to compare the fit of these frameworks with conventional cast prostheses. MATERIALS AND METHODS: The study comprised 20 patients who were provided with 5 standard Brånemark implants each in the edentulous mandible. The fit of the first 10 prostheses with CNC-milled frameworks was measured by means of a 3-dimensional photogrammetric technique. The distortion of the center point of the framework cylinders was measured in relation to the master cast replicas. These measurements were compared with 10 randomly selected routine prostheses with cast frameworks. RESULTS: No significant differences were found between the 2 groups. The 3-dimensional distortion of the cylinders in the completed prostheses ranged from 3 to 80 microns; no passive framework was observed. More distortion was observed in the horizontal plane (x and y axes) as compared to the distortion in the vertical direction (z axis). CONCLUSION: The precision of fit of the first CNC-milled prostheses presented a comparable fit to the conventional cast frameworks. Consequently, this new technique could be a valid option for the routine fabrication of frameworks for implant prostheses.

Computer-Aided Design↗

PubMedDate not supplied

Photogrammetry--an alternative to conventional impressions in implant dentistry? A clinical pilot study.

PURPOSE: The purpose of this clinical pilot study was to describe a photogrammetric technique to determine implant positions in the oral cavity, and to test and compare this technique to conventional impression/master cast procedures for fabrication of titanium frameworks with a computer numeric-controlled (CNC) milling technique. MATERIALS AND METHODS: Implant positions were recorded by means of conventional impressions/master casts as well as intraoral 3-dimensional photogrammetric measurements in 2 patients who were provided with 5 Brånemark implants each in the edentulous mandible. For each patient 2 titanium frameworks were made by means of a CNC milling technique (All-in-One). Both frameworks had an identical design, but the orientations of the framework cylinder fit surfaces were machined either from measurements from the master casts or from the intraoral photogrammetric measurements. The frameworks were tried for fit in the oral cavity and on the master casts. RESULTS: Both cases showed different precision of fit when comparing the 2 frameworks on the master casts. One of the 2 photogrammetric frameworks was not considered acceptable when tried on the models. In the oral cavity, however, all 4 frameworks presented comparable fit, and all were accepted for clinical use. CONCLUSION: The clinical experiences with try-in of the 4 different frameworks indicated that the photogrammetric technique could be a valid option for conventional impressions when using CNC milling fabrication in implant dentistry. The different results from the model and oral examinations also imply the difficulties of assessing clinical fit when testing fit at the master cast level only.

Computer-Aided Design↗

PubMedDate not supplied

A comparison of laser-welded titanium and conventional cast frameworks supported by implants in the partially edentulous jaw: a 3-year prospective multicenter study.

PURPOSE: The purpose of this prospective multicenter study was to evaluate and compare the clinical performance of laser-welded titanium fixed partial implant-supported prostheses with conventional cast frameworks. MATERIALS AND METHODS: Forty-two partially edentulous patients were provided with Brånemark system implants and arranged into 2 groups. Group A was provided with a conventional cast framework with porcelain veneers in one side of the jaw and a laser-welded titanium framework with low-fusing porcelain on the other side. The patients in group B had an old implant prosthesis replaced by a titanium framework prosthesis. The patients were followed for 3 years after prosthesis placement. Clinical and radiographic data were collected and analyzed. RESULTS: Only one implant was lost, and all prostheses were still in function after 3 years. The 2 framework designs showed similar clinical performance with few clinical complications. Only one abutment screw (1%) and 9 porcelain tooth units (5%) fractured. Four prostheses experienced loose gold screws (6%). In group A, marginal bone loss was similar for both designs of prostheses, with a mean of 1.0 mm and 0.3 mm in the maxilla and mandible, respectively. No bone loss was observed on average in group B. No significant relationship (P > 0.05) was observed between marginal bone loss and placement of prosthesis margin or prosthesis design. CONCLUSION: The use of laser-welded titanium frameworks seems to present similar clinical performance to conventional cast frameworks in partial implant situations after 3 years.

Adolescent↗

PubMedDate not supplied

Long-term marginal periimplant bone loss in edentulous patients.

PURPOSE: The aim of this study was to examine the long-term periimplant bone loss in patients treated with implant-supported fixed prostheses in both jaws. MATERIALS AND METHODS: The participants comprised 44 edentulous patients who have been followed for a 15-year period after treatment with a fixed implant-supported prosthesis in the mandible. Thirteen of them also received an implant-supported fixed prosthesis in the maxilla, on average 4.5 years after the mandibular treatment. The periimplant bone level was measured on intraoral radiographs. RESULTS: The long-term results of the implant treatment were successful, and only 1% (3/273) of the implants were lost in the mandible and 7% (5/75) in the maxilla. All but one of the failures occurred before the connection of the prostheses. The mean marginal bone loss around the implants was small (less than 1 mm for a 10-year period after implant placement), and was of similar magnitude in both jaws. However, the individual variation was relatively great. There was no significant difference in marginal bone loss between those who had a maxillary complete denture during the entire observation period and those who had received a fixed implant-supported maxillary prosthesis. Smokers lost more periimplant bone than did the nonsmokers; the difference was significant in the mandible but small and nonsignificant in the maxilla. CONCLUSION: The long-term periimplant bone loss was small and of similar magnitude in the mandible and the maxilla in subjects who had received implant-supported fixed prostheses in both jaws. The prosthetic status in the maxilla, i.e., complete denture or fixed implant-supported prosthesis, had no significant influence on the mandibular periimplant bone loss.

Adult↗

PubMedDate not supplied

Influence of occlusal factors on treatment outcome: a study of 109 consecutive patients with mandibular implant-supported fixed prostheses opposing maxillary complete dentures.

PURPOSE: This study was undertaken to investigate the relationship between occlusal variables and clinical and radiologic findings as well as patient response to treatment outcome in patients with mandibular implant-supported fixed prostheses opposing maxillary complete dentures. MATERIALS AND METHODS: The study group consisted of 109 consecutive patients attending for annual control. They had received their mandibular implant-supported prostheses according to the Brånemark system on average 8 years previously (range 1 to 27 years). All patients were interviewed with standardized questions by one examiner, who also performed the clinical examination. The questions focused on the patients' opinion on masticatory and prosthetic function and problems. The clinical examination comprised occlusal and prosthetic factors and the health of the oral mucosa. RESULTS: The great majority of the patients were very satisfied with their present dental situation and masticatory function. Two thirds reported no problems with their maxillary complete dentures at all. Balanced occlusion was found bilaterally in 61%, and a further 4% had balanced function on one side. More than one third thus lacked balanced occlusion. Only about 60% had optimal occlusion, and 8% had poor occlusion according to common prosthodontic criteria. This was interpreted as a continuing impairment of the occlusion with time. The mean bone loss was 0.5 mm, according to available radiographs, for a mean observation period of 54 months. There were no or only weak correlations between the variables examined. CONCLUSION: The occlusal factors registered were of limited importance for patient satisfaction and treatment outcome recorded clinically and radiographically at follow-up examination of the actual prosthodontic rehabilitation.

Aged↗

PubMedDate not supplied

Factors related to success and failure rates at 3-year follow-up in a multicenter study of overdentures supported by Brånemark implants.

An international prospective study of Brånemark implants retaining overdentures was conducted at nine clinical centers. One hundred thirty-three subjects were recruited in a 12-month period and provided with 510 implants, 117 of which were in maxillae and 393 were in mandibles. This study reports the 3-year follow-up status of 120 overdentures and 444 implants. There were 11 overdenture failures (9.2%). Maxillary overdenture failure rates (27.6%) were nearly nine times greater than mandibular overdenture failure rates (3.3%). Maxillary overdenture treatment was less successful than previously reported fixed implant-supported restorations. However, their mandibular counterparts had success rates slightly higher than those reported for fixed implant-supported restorations. At 3 years, 150 implants remained submerged and 66 implants had been withdrawn because the subjects discontinued study participation. Eleven mandibular and 29 maxillary implants had failed and had been removed from 21 subjects. Logistic regression with forward model selection indicated that one two-way interaction was significantly related to implant failure. At highest risk were the subjects who possessed dental arches with bone quantity E and bone quality 4. Subjects with one implant failure were likely to have more than one failure. The Generalized Estimating Equation was used to adjust for the cluster effect in this population because multiple implants (2 to 6) were placed and evaluated in each of the 133 subjects.

Adult↗

PubMedDate not supplied

Implant treatment in edentulous maxillae: a 5-year follow-up report on patients with different degrees of jaw resorption.

In a retrospective study, 150 patients with edentulous maxillae were selected for treatment with Brånemark implants. The patients were arranged into four different groups, based on jaw shape prior to implant placement. After second-stage surgery, they were provided with either fixed prostheses, removable overdentures followed by fixed prostheses after at least 1 year, or overdentures for the whole period. Patients were followed up for 5 years, with implant and prosthesis survival, annual visits, marginal bone loss, and complications recorded. Results of the study indicated that treatment outcome in edentulous maxillae might be predicted by careful presurgical evaluation of jaw shape. Five-year cumulative implant failure rates varied from 7.9% for patients considered to have enough bone to be provided with fixed prostheses immediately after second-stage surgery to 28.8% for those with severely resorbed jaws receiving an overdenture. The corresponding cumulative prosthesis failure rates were 3.0% and 18.9%, respectively. Patients provided with autogenous bone grafts compared favorably to the group presenting severely resorbed jaws and provided with overdentures, but showed a compromised result compared to the group with the least resorption. Failure of implant treatment correlated significantly with bone quality and ratio of 7-mm implants. All groups, except those treated with bone grafts, showed an average marginal bone level of 1.2 mm after 5 years, irrespective of type of prosthesis. The bone-grafted group showed a corresponding mean level of 2.3 mm after 5 years of function. Regarding clinical complications, a different pattern, mainly related to the type of prosthetic construction used, was observed between the groups. The number of visits clearly indicated that severely resorbed jaws provided with overdentures were the most demanding.

Adult↗

PubMedDate not supplied

Implant treatment in partially edentulous patients: a report on prostheses after 3 years.

There has been an increasing interest in the use of implants for partially edentulous patients. This introduces other biomechanical situations than those experienced in completely edentulous patients. In a prospective multicenter study, 521 implants in 154 patients were loaded with 197 free-standing prostheses. The patients have been followed for 3 years. The cumulative success rate for the prostheses was 94.8% and for the implants it was 93.9%. Most of the lost prostheses were only supported by two implants. A frequent technical complication was fracture and loosening of gold screws, which was more frequent in prostheses supported by only two implants.

Adolescent↗

PubMedDate not supplied

Osseointegrated implants for single-tooth replacement: progress report from a multicenter prospective study after 3 years.

After 3 years, 82 of the original 92 patients remain in this prospective multicenter study of single-tooth restorations supported by Brånemark implants. Since the 1-year follow-up, 6 more patients have been lost, but no additional implants have failed in those patients examined at the 3-year follow-up visit. After 1 year of function, 97.2% of the implants survived in 88 patients, and between the 1- and 3-year follow-up, 100% survived in 82 patients, giving a 3-year cumulative success rate of 97.2%. No changes were observed in the status of gingivitis, pocket depth, periodontal pocket bleeding index, and tooth and implant mobility from those reported after 1 year. Marginal bone resorption remained at a low level--less than 0.1 mm annually during the second and third years. Abutment screw loosening continued, but at a significantly reduced rate from that reported after 1 year. When used, gold rather than titanium abutment screws remained secure.

Adult↗

PubMedDate not supplied

Implant treatment in elderly patients.

A group of 48 patients, all more than 80 years old (mean age 82.7 years) at first implant surgery, who received a total of 254 implants, were followed in one clinical center. Of the exposed implants, 6 of 238 (2.5%) were found to be loose at second-stage surgery, and another 3 implants were lost during the follow-up period. Most patients had minimal postplacement problems, similar to what has been observed in younger patients. However, some patients (10%) experienced obvious problems with general adaptation and muscle control, which has not been observed in younger patients.

Adaptation, Psychological↗

PubMedDate not supplied

In vivo measurements of precision of fit involving implant-supported prostheses in the edentulous jaw.

The objective of this study was to measure and compare the precision of fit of implant-supported prostheses in the edentulous jaw by using both the master cast replicas and the intraoral implants as references. Seven maxillary and 10 mandibular prostheses were randomly selected and measured by means of a three-dimensional (3-D) photogrammetric technique. The results indicated that prostheses routinely connected to osseointegrated implants could demonstrate distortion between the framework and individual implants of up to several hundred microns. When master casts were used as a reference, the mean 3-D distortion of the center point of gold cylinders was 37 microns (SD 18) and 75 microns (SD 40) for mandibular and maxillary prostheses, respectively. The corresponding mean displacement was 90 microns (SD 51) and 111 microns (SD 59), respectively, when the intraoral implants were used as references. The mean 3-D distortion was significantly higher for the intraoral measurements in both arches (P < .001 and P < .05). Furthermore, the overall distortion was significantly higher for the maxillary prostheses when the master casts were used as the reference (P < .05). However, for the intraoral measurements, no statistically significant difference of fit between the arches was possible to observe (P < .05). This could possibly be explained by the finding that intraoral measurements of the mandibular prostheses indicated a deformation and rotation of the mandible that was not observed in the maxillary prostheses. A further factor in the lack of statistical significance could be the relatively small sample size.

Dental Abutments↗

PubMedDate not supplied

A 5-year prospective multicenter follow-up report on overdentures supported by osseointegrated implants.

This report presents the results of a 5-year prospective multicenter study including nine centers worldwide. A total of 30 patients received 117 Brånemark implants in the maxillae, and 103 patients received 393 implants in the mandibles. According to the protocol, all integrated maxillary implants were to be loaded; however, only two of four mandibular implants were planned for support of the overdentures, leaving the remaining implants covered by mucosa as backup for possible implant failures. Thirty-five patients (26.3%) who were provided with 127 implants (24.9%) were withdrawn from the study. Six patients treated in the maxilla lost all their implants and resumed wearing complete dentures. The cumulative success rates for implants and for overdentures supported by two implants in the edentulous mandible were 94.5% and 100%, respectively. The corresponding cumulative success rates for implants and for overdentures supported by an optimal number of implants in the maxilla were 72.4% and 77.9%, respectively. Significantly better jawbone characteristics at the time of implant surgery were considered to contribute to the better cumulative success rates in the mandibles. Mean marginal bone loss was 0.8 mm (SD 0.8) and 0.5 mm (SD 0.8) for loaded implants during a 5-year period of time in the maxillae and mandibles, respectively. Measurements of the clinical height of the abutment cylinders indicated a mean recession (0.2 mm) of peri-implant mucosa during the follow-up period in the mandibles. Conversely, hyperplasia was observed in the maxillae.

Adult↗

PubMedDate not supplied

Osseointegrated implants for single-tooth replacement: a prospective 5-year multicenter study.

One hundred seven Brånemark implants were placed in 92 patients participating in an international multicenter trial on single-implant restorations at seven centers. The patients were followed for 5 years in a prospective study focusing on implant success and crown function. Plaque and gingival indexes, as well as probing depths, were recorded around teeth and implants. The marginal bone level at implants was determined from intraoral radiographs. Only three implants (2.8%) had been lost at the final annual checkup. During the follow-up period, a total of 17 patients dropped out or were excluded because of nonconformity with the protocol. Based on the remaining patients, a total of 86 implants were clinically and radiographically evaluated at the 5-year follow-up period, resulting in a cumulative success rate of 96.6% (71 implants) in the maxillae and 100% (15 implants) in the mandibles. Plaque and gingival indexes showed a similar pattern of good health around both natural teeth and titanium abutments. The marginal bone loss during the 5-year period did not exceed 1 mm as a mean for all implants analyzed. The most frequent complication recorded during the follow-up was loosening of the abutment fixation screw. The outcome of this study indicated that safe and highly predictable results can be obtained for 5 years when Brånemark implants are used to support single-tooth restorations.

Alveolar Bone Loss↗

PubMedDate not supplied

Prosthesis misfit and marginal bone loss in edentulous implant patients.

The objective of this study was to statistically correlate in vivo measurements of prosthesis misfit and change of marginal bone level in implants placed in the edentulous maxilla. Two groups, each comprising seven patients, were followed up either prospectively for 1 year or retrospectively for the last 4 years of the 5-year period after second-stage surgery. Measurements of prosthesis misfit were performed by means of a three-dimensional photogrammetric technique, and marginal bone levels were measured from standard intraoral radiographs. Results showed that none of the prostheses presented a completely passive fit to the implants in vivo. Furthermore, similar distortions of the prostheses were found in the two groups, indicating that the implants seemed to be stable and did not move, even after several years in function. The maximal range of three-dimensional distortion of cylinder center points was about 275 microns for both groups. Mean center point misfit was 111 (SD 59) and 91 (SD 51) microns for the 1-year and 5-year groups, respectively. The corresponding mean marginal bone loss was 0.5 and 0.2 mm for the two follow-up groups. No statistical correlations (P > .05) between change of marginal bone levels and different parameters of prosthesis misfit were observed in the two groups. The study indicated that a certain biologic tolerance for misfit may be present. The degree of misfit reported in the study was clinically acceptable with regard to observed marginal bone loss.

Adaptation, Physiological↗

PubMedDate not supplied

A qualitative and quantitative method for evaluating implant success: a 5-year retrospective analysis of the Brånemark implant.

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.

Adult↗

PubMedDate not supplied

Prosthodontic treatment, patient response, and the need for maintenance of complete implant-supported overdentures: an appraisal of 5 years of prospective study.

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.

Alveolar Bone Loss↗

PubMedDate not supplied

Customized titanium single-implant abutments: 2-year follow-up pilot study.

PURPOSE: The aim of this study was to describe an alternative technique to fabricate single-implant restorations by using adjustable titanium abutments with porcelain applied directly to the abutment, and to follow an early group of patients treated with these crowns. MATERIALS AND METHODS: Seventeen randomly selected single crowns were consecutively placed in 14 patients and then followed for 2 years. A protocol of using healing abutments, implant impressions, and adjustment of the final abutment in the laboratory was used to fabricate the crowns. RESULTS: The clinical result revealed few clinical problems, and the mean marginal bone loss was 0.4 mm (standard deviation +/- 0.57 mm) after 1 year in function. CONCLUSION: The conclusion drawn, based in part on published literature, was that occurrence of mucosal inflammation and marginal bone loss was not related to the use of the present protocol.

Alveolar Bone Loss↗