Biomedical subjects

Anders Ortorp

Publications and source records attributed to Anders Ortorp.

8 recordsLinked to original sources

PubMed2006

Clinical experiences with laser-welded titanium frameworks supported by implants in the edentulous mandible: a 10-year follow-up study.

BACKGROUND: Long-term follow-up studies for more than 5 years are not available on laser-welded titanium frameworks. PURPOSE: To report and compare 10-year data on implant-supported prostheses in the edentulous mandible provided with laser-welded titanium frameworks and conventional gold alloy frameworks. MATERIALS AND METHODS: Altogether, 155 patients were consecutively treated with prostheses at abutment level with two generations of fixed laser-welded titanium frameworks (test groups). A control group of 53 randomly selected patients with conventional gold alloy castings was used for comparison. Clinical and radiographic 10-year data were collected for the three groups. RESULTS: All patients followed-up for 10 years (n=112) still had fixed prostheses in the mandible (cumulative success rate [CSR] 100%). The overall 10-year cumulative success rate (CSR) was 92.8 and 100.0% for titanium and gold alloy frameworks, respectively. Ten-year implant cumulative survival rate (CSR) was 99.4 and 99.6% for the test and control groups, respectively. Average 10-year bone loss was 0.56 (SD 0.45) mm for the titanium group and 0.77 (SD 0.36) mm for the control group (p < 0.05). The most common complications for titanium frameworks were resin or veneer fractures, soft tissue inflammation, and fractures (12.9%) of the metal frame. Loose and fractured implant screw components were below 3%. CONCLUSION: Excellent overall long-term results with 100% CSR could be achieved with the present treatment modality. Fractures of the metal frames and remade prostheses were more common for the laser-welded titanium frameworks, and the first generation of titanium frameworks worked poorly when compared with gold alloy frameworks during 10 years (p < 0.05). However, on average more bone loss was observed for implants supporting gold alloy frameworks during 10 years. The reasons for this difference are not clear.

Adult↗

PubMed2005

Photogrammetry and conventional impressions for recording implant positions: a comparative laboratory study.

BACKGROUND: The development of digitized techniques for manufacturing implant frameworks has made possible alternative "impression" techniques for recording implant positions. PURPOSE: The objective of the present study was to test the precision and accuracy of a three-dimensional photogrammetric technique to record implant positions in vitro and to compare casts made with this technique with conventional casts fabricated with two conventional impression techniques. MATERIALS AND METHODS: Twenty casts were fabricated from 10 polyether (Impregum, ESPE Dental AG, Seefeld, Germany) impressions and 10 plaster (Kühns Abdrucksgips, Ernst Hirnischs GmbH, Goslar, Germany) impressions of one master model. The casts were measured in a coordinate measuring machine (Zeiss Prismo VAST, Oberkochen, Germany) and compared with the master model. Six separate three-dimensional photographs of the master model were taken with a special camera. After the photographs were measured with an analytic plotter, results were analyzed and compared to the coordinates of the original model and casts. RESULTS: A systematic pattern of distortion in the x-axis was found for the two impression techniques. Expansion of the implant arch at the terminal implants (p < .01) averaged 22 microm and 94 microm on photographs and plaster casts, respectively. Polyether casts contracted an average of 52 microm when compared with the master (p < .01). In absolute figures, photogrammetry and the polyether technique reproduced the x-axis and three-dimensional parameters more accurately than the plaster technique did when cylinder center point distortion was compared (p < .05 to p < .001). However, angular cylinder distortion in absolute figures was greater with the photographic technique than with either of the impression techniques (p < .05-p < .001). CONCLUSION: Photogrammetry is a valid option for recording implant positions and has a precision comparable to that of conventional impression techniques. At present, however, it is limited to framework fabrication techniques that are based on digital platforms.

Calcium Sulfate↗

PubMed2005

Screw preloads and measurements of surface roughness in screw joints: an in vitro study on implant frameworks.

BACKGROUND: With the development of milled titanium implant frameworks, new surfaces that have not previously been studied are now being used in screw joints. PURPOSE: The aims of the present study were to compare the preload produced in screw-retained titanium and gold alloy frameworks and the preload for titanium frameworks before and after the application of veneers. Another aim was to try to relate the surface roughness of the screw joints to variations in preload. MATERIALS AND METHODS: Ten identical titanium and five gold alloy frameworks were fabricated. The gold screws were tightened to 10 Ncm. Preload measurements were made for the gold alloy frameworks and before and after the porcelain or acrylic resin veneers had been applied to the titanium frameworks. Surface roughness measurements were made after preload measurements on the screw joint surfaces of the titanium frameworks and corresponding gold screws. RESULTS: The preloads for the titanium and gold alloy frameworks were similar. Preload in both types of frameworks decreased after repeated torques (p<.05-.01) but was unaffected by the application of veneering materials to the titanium frameworks (p>.05). No relationship (p>.05) between preload and surface roughness characteristics was observed. Loaded titanium framework screw sites, however, had lower mean S(a) values than unloaded sites (p<.001), whereas the surfaces of loaded gold screws had higher mean S(a) values compared with the surfaces of control gold screws (p<.05-.001). CONCLUSION: When using gold screws, milled titanium frameworks have preloads similar to those of gold alloy frameworks and preloads for both decrease after repeated tightening. The preload was similar before and after the veneering of the titanium frameworks. Unloaded milled titanium screw sites had rougher surfaces than loaded, and loaded gold screws had rougher surfaces than unloaded. However, no correlation between screw joint surface and preload was observed for veneered titanium frameworks.

Computer-Aided Design↗

PubMed2005

On titanium frameworks and alternative impression techniques in implant dentistry.

PURPOSE: The objectives of this thesis were to compare the clinical and material performance of implant-supported titanium frameworks with gold-alloy frameworks in the edentulous jaw and to test a digitized impression technique to optimize material characteristics and clinical and laboratory procedures. MATERIALS AND METHODS: Two different kinds of laser-welded titanium frameworks and one type of digitized computer numeric controlled (CNC)-milled titanium framework for the edentulous jaw were evaluated and compared with gold-alloy frameworks in two clinical 5-year follow-up studies. The CNC frameworks were also evaluated and compared with gold-alloy frameworks in two experimental studies according to fit, preload, and surface roughness. Furthermore, a digitized photogrammetric technique for recording implant positions in the edentulous jaw was experimentally tested and compared with two conventional impression techniques. RESULTS: Laser-welded titanium frameworks had a lower success rate after 5 years in function than gold-alloy frameworks. The 5-year performance of CNC frameworks was similar to that of gold-alloy frameworks. The fit and precision of implant-supported CNC frameworks was significantly better compared with gold-alloy frameworks. Applications of veneering material did not significantly affect the fit of the titanium frameworks. The preload of CNC frameworks was similar to that of gold-alloy frameworks, both exhibiting significantly decreased preloads after repeated tightening. The preloads of titanium frameworks were similar before and after veneering. Unloaded milled titanium screw sites had significantly rougher surfaces than loaded sites, and loaded gold screws had rougher surfaces than unloaded. No correlation between surface of the screw joints and preload of veneered titanium frameworks was observed. The precision of photogrammetric impressions was comparable to that of conventional impression techniques. CONCLUSIONS: Implant-supported CNC-milled titanium frameworks are a viable alternative to gold-alloy castings in the edentulous jaw, and because a digital platform is used to manufacture these titanium frameworks, photogrammetric impressions can be made.

Adult↗

PubMed2004

Fixed implant-supported prostheses in elderly patients: a 5-year retrospective study of 133 edentulous patients older than 79 years.

BACKGROUND: An increasing number of elderly patients are treated with implants, but results for the elderly patient in terms of implant success and adaptation to implant prostheses are contradictory. OBJECTIVE: To retrospectively study the 5-year clinical and radiologic performances of fixed implant-supported prostheses placed in edentulous elderly patients and to compare those results with the results of using similar prostheses in a control group of younger patients. MATERIALS AND METHODS: The study group comprised 133 edentulous patients who were 80 or more years of age and who were consecutively treated with fixed implant-supported prostheses between January 1986 and August 1998. Altogether 761 Brånemark System implants (Nobel Biocare AB, Göteborg, Sweden) were placed in 139 edentulous jaws. The control group comprised 115 edentulous patients who were younger than 80 years and who were treated consecutively from March 1996 to November 1997 with similar prostheses. In this group 670 implants were placed in 118 edentulous jaws. Information was collected from all postinsertion visits, including the fifth annual checkup, and changes of marginal bone levels were analyzed from intraoral radiographs. RESULTS: The 5-year cumulative survival rate (CSR) for implants in the maxilla was 93.0% in the study group and 92.6% in the control group; the corresponding CSRs for implants in the mandible were 99.5% and 99.7%. The most common complications for patients in the study group were soft tissue inflammation (mucositis) and cheek and lip biting (p < .05) whereas resin veneer fractures were the most common complications for the control group. Overall 5-year marginal bone loss for the study group was 0.7 mm (standard deviation [SD], 0.45) in the upper jaw and 0.6 mm (SD, 0.50) in the lower jaw. Differences in bone levels and bone loss between the two groups did not reach significant levels (p > .05). CONCLUSIONS: Implant treatment in the elderly patients showed treatment results comparable to those observed in younger age groups. However, indications of more problems with adaptation could be observed and were reflected in more postinsertion problems. Cleaning problems and associated soft tissue inflammation (mucositis) as well as tongue, lip, and cheek biting were significantly more often observed among the elderly patients (p < .05).

Adaptation, Physiological↗

PubMed2004

Clinical experiences of computer numeric control-milled titanium frameworks supported by implants in the edentulous jaw: a 5-year prospective study.

BACKGROUND: Few long-term follow-up studies on treatment concepts using computer numeric control-milled titanium frameworks have been conducted. OBJECTIVE: To evaluate the clinical and radiographic performance of implant-supported prostheses provided with computer numeric control-milled titanium frameworks in the edentulous jaw and to compare their performance during the first 5 years of function with that of prostheses provided with conventional cast gold alloy frameworks. MATERIALS AND METHODS: A consecutive group of 126 edentulous patients were randomly provided with 67 prostheses with titanium frameworks (test group) in 23 upper jaws and 44 lower jaws and with 62 conventional prostheses with gold alloy castings (control group) in 31 upper jaws and 31 lower jaws. Clinical and radiographic 5-year data were collected for the test and control groups. RESULTS: The frequency of problems was low, and clinical and radiologic performances were similar in both groups. In the test group, the 5-year cumulative survival rates (CSRs) were 94.9% and 98.3% for implants and titanium prostheses, respectively. The respective corresponding CSRs for the control group were 97.9% and 98.2%. More loaded implants were lost in the maxillas in the test group (p < .01), but this difference was not significant on the patient/prosthesis level (p > .05). Smokers lost more implants than nonsmokers lost (p < .01). Similar survival rates were observed for implants in the mandible. One prosthesis was lost in each group because of the loss of implants. Metal fractures were seen only in the control group, and resin veneer fractures were more frequent in the maxilla in the gold alloy group (p < .05). In the test group, the mean marginal bone loss was 0.5 mm (SD, 0.44) in the maxilla and 0.4 mm (SD, 0.50) in the mandible. A similar pattern of bone reaction was observed in the control group. Mean marginal bone loss was similar for smokers and nonsmokers (p > .05). CONCLUSION: Computer numeric control-milled titanium frameworks are a viable alternative to gold alloy castings in the edentulous jaw and present clinical and radiologic performances similar to those of conventional gold alloy frameworks during the first 5 years of function.

Aged↗

PubMed2002

Clinical experience of CNC-milled titanium frameworks supported by implants in the edentulous jaw: a 3-year interim report.

BACKGROUND: The use of computer numeric controlled (CNC)-milled titanium frameworks is a new technique for framework fabrication, and few clinical reports have been made on this treatment modality. PURPOSE: The goal of this study was to report the clinical performance of implant-supported prostheses with CNC-milled titanium frameworks in the edentulous jaw and to compare the results with prostheses provided with conventional cast frameworks during the first 3 years of function. MATERIALS AND METHODS: A consecutive group of 126 edentulous patients were provided by random distribution with 67 prostheses with CNC-milled titanium frameworks in 23 upper and 44 lower jaws and 62 conventional prostheses with gold-alloy castings in 31 upper and 31 lower jaws. Radiographic 1-year data and clinical 3-year data were collected for both the titanium and control group. RESULTS: One prosthesis was lost in each group owing to loss of implants, and the overall 3-year prosthesis cumulative survival rate was 98.2% for both groups. Patients with smoking habits experienced significantly more implant failures than nonsmokers (p =.006). Few problems were observed. No metal fractures were seen in the test group, whereas two frameworks and one abutment screw fractured in the control group. Resin veneer fractures were the most common complication, with a slightly higher incidence observed in the control group. CONCLUSIONS: Computer numeric controlled-milled titanium frameworks can be used as an alternative to conventional castings in the edentulous jaw, presenting clinical performance similar to that of conventional cast frameworks during the first 3 years of function. key words: computer numeric controlled, implant supported, prostheses, titanium

Computer-Aided Design↗

PubMedDate not supplied

Comparisons of precision of fit between cast and CNC-milled titanium implant frameworks for the edentulous mandible.

PURPOSE: The purpose of this study was to investigate and compare the precision of fabrication in repeatqdly produced computer numeric controlled (CNC)-milled frameworks with consventional castings, and to analyze the distortion from application of different veneering materials. MATERIALS AND METHODS: Twenty identical titanium frameworks were fabricated by means of a CNC milling technique for the same master model. Five conventional frameworks were cast as a control group to the same model. The frames were measured with regard to fit in a coordinate measuring machine linked to a computer. Measurements were made during different stages of handling of the titanium framework, and after veneering materials had been applied. RESULTS: The CNC frameworks showed a statistically better fit and precision of fabrication compared to conventional castings (P < .05). The application of veneering material did not statistically affect the fit of the titanium frameworks (P > .05). CONCLUSION: It is possible to fabricate implant-supported frameworks by means of the present CNC technique with a very high precision and repeatability.

Acrylic Resins↗