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Biomedical subjects

I P van Rossen

Publications and source records attributed to I P van Rossen.

5 recordsLinked to original sources

A clinical retrospective evaluation of FA/HA coated (Biocomp) dental implants. Results after 1 year.

In this retrospective clinical evaluation, the performance of loaded titanium implants with a bilayer bioactive surface coating of the relatively reactive hydroxylapatite (HA, outer layer) and the more stable fluorapatite (FA, inner layer) was evaluated. 98 consecutive patients were included in the study for a total of 354 implants, loaded by overdentures, fixed partial dentures and single tooth replacements. Statistical analyses revealed a cumulative probability of implant survival on a per patient basis of 94.5% (s.e. 2.7%), one year after implant installation. On implants that were lost parts of the bilayer FA/HA coating had vanished as a result of primary or secondary infection and subsequently epithelial down growth. Most complications were associated with implants placed in the maxilla. Periotest values (PTV) were generally high, indicating adequate osseointegration. The PTV's were statistically significantly less favorable in implants placed in the maxilla. The most favorable PTV's and gingival index scores were found around implants servicing overdentures. Marginal bone loss averaged approximately 2mm during the observation period. The amount of marginal bone loss corresponded with the distance from the neck of the implant to the first thread of the implant's cervical screw-section. It is concluded that, during the relatively short observation period, the FA/HA coated implants function adequately. However, in the absence of a direct implant-to-bone contact preceding implant loss, part of the FA/HA coating on the titanium implants generally dissolves.

Adult↗

A model for the evaluation of mandibular bone response to implant materials.

An in vivo animal (goat) mandibular bone model has been evaluated for the cortical and trabecular bone response to biomaterials with different elastic modulus and/or different surfaces. The effect of the elastic modulus on the bone formation was also studied. The difficulties encountered in orientation of the implants probably could have been surmounted if pre-operative radiographs had been available. It was also established that there is a large variance in the amount of trabecular and cortical bone in the mandible of the goat 'bone model'.

Aluminum Oxide↗

Delayed implants in the anterior maxilla with the IMZ-implant system: a radiographical evaluation.

One hundred and seventy-three IMZ-implants in 81 patients, placed in the anterior region of the maxilla, were evaluated radiographically by two observers. Radiographs were evaluated at three intervals, namely at the time of implant placement, the time of prosthetic restoration and at the latest available radiograph, on average 2 1/2 years after implant placement. In this study marginal bone height and the type of radiolucency adjacent to the implant were determined. Both observers were able to classify the marginal bone height (mesial and distal) and the distinctive type of resorptive defects to an acceptable level of agreement, with Cohen's kappa ranging between 0.48 and 0.69. It was found that, at the most recent visit to the clinic, angular-shaped resorptive defects are found mesially and/or distally of the implants at approximately 25% of the implants. At this stage 20.7% of the mesial implant sites and 27.9% of the distal implant sites show marginal bone heights less than three-quarters of the implant length. These findings do not fully underscore and sometimes even contradict the clinical observations which were considered highly satisfactory.

Alveolar Bone Loss↗

Stress-absorbing elements in dental implants.

By means of finite element analysis, calculations, were made of the stress-distribution in bone around implants with and without stress-absorbing elements. A freestanding implant and an implant, it was concluded the variation in the E-modulus of the stress-absorbing element had no effect on the stresses in bone. Changing the shape of the stress-absorbing element had little effect on the stresses in cortical bone. For the implant connected with a natural tooth, it was concluded that a more uniform stress was obtained around the implant with a low E-modulus of the stress-absorbing element. It was also concluded that the bone surrounding the natural tooth showed a decrease in the height of the peak stresses.

Computer Simulation↗