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Biomedical subjects

I Naert

Publications and source records attributed to I Naert.

At least 73 records · Page 4Linked to original sources
PubMed1992

A six-year prosthodontic study of 509 consecutively inserted implants for the treatment of partial edentulism.

A total of 509 consecutive Brånemark TM implants (Nobelpharma AB, Gothenburg, Sweden) were inserted in 146 patients between December 1982 and May 1989, on which 217 fixed partial dentures were planned. The cumulative failure rates after abutment connection were 3.9% and 4.1% for the maxillae and mandible, respectively. The lack of continuous prosthesis stability was limited to 4.1% for the maxillae and 5.4% for the mandible. The average annual marginal bone loss was 0.77 mm (SD = 1.0) and 0.96 mm (SD = 0.9) for the maxillae and mandible, respectively, during the first year and averaged 0.1 mm for the following years. The mode of connection between teeth and implants or the use of porcelain instead of composite resin as occlusal material did not influence the marginal bone height around the implants. Technical complications were most often related to the materials used. The results of a medium-term follow-up encourage the use of the Brånemark osseointegration system in the treatment of partial edentulism.

Adult↗
PubMed1992

A study of 589 consecutive implants supporting complete fixed prostheses. Part II: Prosthetic aspects.

In 91 consecutive edentulous patients, 103 jaws were treated with complete fixed prostheses supported by Brånemark Implants (n = 589). As a result of fixture loss in each of two patients (two jaws), an overdenture instead of a fixed prosthesis was installed. For one patient (two jaws), data were not available after abutment connection. At the end of the seventh year, the cumulative failure rates for the remaining 99 prostheses reached 4.9% for mandibles and 10.1% for maxillae. After loading, 12 fixtures showed signs of nonintegration, but only one patient had to revert to complete dentures. Neither the fixture location nor the cantilever length revealed a significant difference in marginal bone loss around the supporting fixtures. Patients with fixture-supported fixed prostheses in both jaws showed significantly more marginal bone loss than did those with only one fixed prosthesis opposed by either natural dentition (50%) or a complete denture (50%). Component complications were limited to fixture fracture (3/564), abutment screw fracture (5/564), and gold screw fracture (7/564). The predictability of Brånemark implants in the treatment of completely edentulous jaws is confirmed.

Alveolar Bone Loss↗
PubMed1992

Posterior jaw bone resorption in osseointegrated implant-supported overdentures.

For several years, osseointegrated implant-supported overdentures have been used in the rehabilitation of full edentulism with excellent results, at least in the lower jaw. This study involved 3 groups of patients with different prosthetic reconstructions: (1) mandibular overdentures supported by 2 implants connected by a bar (30 patients), (2) mandibular fixed prostheses supported by 4-6 implants (25 patients) and (3) mandibular complete dentures without implant support as controls (85 patients). The primary aim of this study was to examine on orthopantomograms (by means of the area index to minimize distortion and magnification errors), posterior mandibular ridge resorption in the 3 treatment groups. The present data demonstrated a minimal posterior mandibular ridge resorption in patients with fixed implant-supported prostheses. A more considerable posterior ridge resorption was observed in the complete denture group and especially in the overdenture wearers. For the latter, the annual posterior jaw bone resorption after the post-extraction remodeling period of 6 months, was 2- to 3-fold that of full denture wearers. When patients were edentulous for more than 10 years, the difference between the 2 latter groups disappeared. It is suggested that although the overdenture design on 2 implants offers advantages from a financial and failure rate point of view, its indications in younger patients should cautiously be evaluated in a long-term perspective concerning posterior mandibular bone resorption.

Adolescent↗
PubMed1992

Fixture design and overload influence marginal bone loss and fixture success in the Brånemark system.

It has been documented that the long-term clinical outcome of the Brånemark system is very favourable. However, failures do occur before and after loading. This study examined the differences in marginal bone loss between standard and self-tapping fixtures and attempted to explain excessive marginal bone loss or loss of osseointegration during the first 3 years of loading. Marginal bone loss (scored on long cone radiographs) and fixture failure rate were compared for different fixture designs. For standard fixtures, in comparison with self-tapping fixtures, the failure rate was clearly higher before as well as after loading. However, for successful fixtures no difference in marginal bone loss was observed. For the conical fixtures an increased marginal bone loss around the smooth part was observed. The effect of fixture overload, marginal bone height and loss of osseointegration was examined in 69 patients with 1 and 15 patients with 2 fixed full prostheses, and in 9 patients with an overdenture in the upper jaw. Excessive marginal bone loss (more than 1 mm) after the first year of loading and/or fixture loss correlated well with the presence of overload due to a lack of anterior contact, the presence of parafunctional activity and osseointegrated full fixed prostheses in both jaws.

Adolescent↗
PubMed1992

Periodontal aspects of osseointegrated fixtures supporting a partial bridge. An up to 6-years retrospective study.

The present paper reports on the use of osseointegrated titanium fixtures (Brånemark) in partially edentulous patients. The tissue reactions around 509 implants in 97 upper and 71 lower jaws of 146 consecutive patients, rehabilitated by means of partial bridges--supported by implants only (60%) or by the combination of teeth and implants (40%)--were observed longitudinally. The mean number of implants per bridge was 2.40 (range 1-5) for the upper jaw and 2.06 (range 1-5) for the lower jaw respectively. Before loading, a total of 23 fixtures were lost, 15 in the upper and 8 in the lower jaw. This loss could partially be correlated to per- and post-operative complications and to fixture characteristics (length, self-tapping or not). After a loading time of 30 months (range 2 to 77 months), 6 implants, 2 in the upper and 4 in the lower jaw, showed symptoms of non-integration. The cumulative failure rate for the individual fixtures after a 6-year period reached 5.7 and 6.5% for the upper and lower jaw, respectively. The mean annual marginal bone loss, scored on standardized radiographs, was 0.9 mm during the 1st year and 0.1 mm the following years. This loss in marginal bone height was equal in the upper and lower jaws and not related to the type of occlusal material of the bridges. The present data showed that the cumulative failure rate for Brånemark implants supporting partial bridges can be limited to 6% after a 6-year period, and that the radiographic bone loss is comparable with that found around fixtures supporting full bridges.

Adult↗
PubMed1991

Prosthetic aspects of osseointegrated fixtures supporting overdentures. A 4-year report.

Eighty-six consecutive patients, provided with 84 resilient and two nonresilient overdentures (six in the upper and 80 in the lower jaw), were examined. The overdentures were supported by a total of 173 osseointegrated titanium fixtures (the standard Branemark abutment), with a mean loading time of 19.1 months (range 4 to 48 months). In each jaw only two fixtures anchored the overdentures. No failures occurred during the observation period but two fixtures were lost before loading. The radiographic annual bone loss around fixtures in the lower jaw was -0.8 mm for the first year and less than -0.1 mm for the following years. The change in marginal bone height did not correlate with parameters such as the occlusion and articulation pattern, the presence or absence of a soft liner around the abutments, and the magnitude of the interabutment distance. The patients' reactions to overdenture treatment were, on the whole, positive concerning chewing function, phonetics, and comfort. The need for maintenance care of the clip-bar attachment was minimal.

Adult↗
PubMed1991

Periodontal aspects of osseointegrated fixtures supporting an overdenture. A 4-year retrospective study.

196 Brånemark implants in 86 consecutive patients rehabilitated by means of overdentures (6 upper jaws, 80 lower jaws) were observed longitudinally. In each jaw, only 2 implants were used to anchor the overdenture. 2 implants in the lower jaw showed some mobility at the abutment installation and were removed immediately. During the loading period (mean loading time 19.1 months ranging from 4 to 48 months), none of the implants showed any signs of non-integration. The marginal tissue reaction and plaque accumulation were monitored using conventional indices. Clinical methods and standardized radiographs were used to evaluate the bone level and density. The numbers of approximal surfaces without plaque (40%) or with gingival inflammation (55%) were almost constant throughout the study. The probing pocket depths remained within the range of 2.7 to 3.2 mm during the observation time, whereas the distance of the gingival margin from the top of the abutment clearly increased (from 1.8 to 2.9 mm). For loaded lower jaw implants connected to each other with a straight bar, a radiographic bone loss of 0.8 mm was observed during the first postsurgical year followed by a mean annual bone loss of less than 0.1 mm. For the "sleeping" fixtures, 50% less bone loss was recorded. For loaded but not interconnected implants in the upper jaw, the bone loss during the first 6 months reached 2.0 mm. The loss in marginal bone height did not clearly correlate with parameters such as the plaque index, the gingivitis index, the presence or absence of gingiva around the abutment, or the implant length. The present data, with an observation time up to 4 years, showed that the failure rate for Brånemark implants supporting overdentures in the lower jaw can be limited to 1%. However, the use of 2 unconnected fixtures in the upper jaw cannot presently be advocated since considerable bone loss was observed.

Adult↗
PubMed1991

The rehabilitation of oral defects by osseointegrated implants.

So far, preprosthetic surgery for oral defects improved prosthetic retention problems for only a limited amount of time and led to many side-effects. The alternative offered by the osseointegration technique developed by P.-I. Brånemark changed the concept of preprosthetic surgery dramatically. By means of a few permucosal titanium screws, bridges or overdentures can be retained even in cases of advanced jaw bone resorption. When the latter is extreme, an autologous free bone graft fixed by means of self-tapping titanium implants can offer the necessary support for sometimes elaborate prosthetic reconstructions. The marginal bone loss around Brånemark implants is very limited after a 1st year of bone remodelling, even when an autologous transplant has been used.

Dental Implantation, Endosseous↗
PubMedDate not supplied

Assessment of mechanobiological models for the numerical simulation of tissue differentiation around immediately loaded implants.

Nowadays, there is a growing consensus on the impact of mechanical loading on bone biology. A bone chamber provides a mechanically isolated in vivo environment in which the influence of different parameters on the tissue response around loaded implants can be investigated. This also provides data to assess the feasibility of different mechanobiological models that mathematically describe the mechanoregulation of tissue differentiation. Before comparing numerical results to animal experimental results, it is necessary to investigate the influence of the different model parameters on the outcome of the simulations. A 2D finite element model of the tissue inside the bone chamber was created. The differentiation models developed by Prendergast, et al. ["Biophysical stimuli on cells during tissue differentiation at implant interfaces", Journal of Biomechanics, 30(6), (1997), 539-548], Huiskes et al. ["A biomechanical regulatory model for periprosthetic fibrous-tissue differentiation", Journal of Material Science: Materials in Medicine, 8 (1997) 785-788] and by Claes and Heigele ["Magnitudes of local stress and strain along bony surfaces predict the course and type of fracture healing", Journal of Biomechanics, 32(3), (1999) 255-266] were implemented and integrated in the finite element code. The fluid component in the first model has an important effect on the predicted differentiation patterns. It has a direct effect on the predicted degree of maturation of bone and a substantial indirect effect on the simulated deformations and hence the predicted phenotypes of the tissue in the chamber. Finally, the presence of fluid also causes time-dependent behavior. Both models lead to qualitative and quantitative differences in predicted differentiation patterns. Because of the different nature of the tissue phenotypes used to describe the differentiation processes, it is however hard to compare both models in terms of their validity.

Animals↗
PubMedDate not supplied

Evaluation of Ca-P coatings in animal experiments: importance of study design.

During the last decennium the research on oral implants has increased considerably. A lot of different implant materials and types have been tested, but differences in study design and evaluation criteria make comparison of the results difficult. The purpose of this paper is to discuss surgical, statistical, and histological methods for testing and evaluating the biocompatibility of oral implants. Many formulas are available for calculating the required group size. The paper describes how such calculations can be used for the evaluation of implants and reviews the preferred surgical techniques. The control of various external influences that can contribute to the variability in obtained data are discussed. After implantation, the implants with their surrounding tissues are retrieved and subjected to histological evaluation. Currently, because of technical limitations, light microscopical sectioning is still the preferred preparation technique. After sectioning, quantitative analysis has to be performed. The parameters that can be evaluated are described. Finally, the use and potential of the described techniques are demonstrated with two examples.

Animals↗
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

Within-subject comparison between connected and nonconnected tooth-to-implant fixed partial prostheses: up to 14-year follow-up study.

PURPOSE: This long-term follow-up study aimed to compare the outcome of fixed prostheses supported by teeth and implants and by freestanding implants only. MATERIALS AND METHODS: From prosthesis insertion up to 14 years (mean 6.5 y), 18 patients were followed. Implant-supported prostheses with and without tooth connection were compared within the same jaw. The tooth-implant prostheses were supported by 30 implants and 30 teeth, and the freestanding prostheses were supported by 48 implants. Implant outcome, marginal bone stability, and mechanical complications were recorded. RESULTS: Neither implant mobility nor fractures of any component of the implants were observed. No prosthesis complications were observed, and the same applied for crown cement failure and intrusion of teeth. Only one periapical lesion was detected at the first follow up. The annual change of the marginal bone level around connected and freestanding implants did not differ significantly. The mean marginal bone loss (over the 2 groups) for the first 6 months amounted to 1.08 mm. After the first 6 months, an annual marginal bone loss of 0.015 mm was observed. There was no difference between the 3 connection types (single implant connected to single tooth, multiple implants and/or multiple teeth connected with single connector, and multiple connectors) for the first 6 months or thereafter. The marginal bone loss (over the 3 groups) for the first 6 months was 1.15 mm. After the first 6 months, the annual bone loss (over the 3 groups) amounted to 0.015 mm. CONCLUSION: Based on the results of this study, splinting teeth with implants for implant-supported fixed prostheses did not affect the long-term outcome in comparison to freestanding implants.

Adult↗
PubMedDate not supplied

Mechanical state assessment of the implant-bone continuum: a better understanding of the Periotest method.

The aim of this study was to obtain a better understanding of the Periotest method when used to detect subclinical mobility of osseointegrated implants. Four hundred two screw-shaped implants were tested with the Periotest device at the time of abutment connection. Several factors, including jaw location, implant and abutment length, and gender, were related to Periotest values (PTVs). Implants located in the anterior region of the mandible showed the lowest mean PTV (-3.2). The influence of abutment and implant length upon PTVs could be detected in the maxilla. In the mandible, only abutment length had influence on PTVs. Women showed higher mean Periotest scores in the maxilla compared with men. This difference was not found in the mandible. The Periotest method, its clinical limitations, and the meaning of a given PTV are also discussed.

Adult↗
PubMedDate not supplied

Computer-assisted planning of oral implant surgery: a three-dimensional approach.

A planning system for oral implant surgery based on a true three-dimensional approach is described. This system allows the interactive placement and adjustment of axial-symmetric models representing implants in the jawbone structures visible on computerized tomographic volume data. Simultaneous visualization is possible on two-dimensional reformatted images and on three-dimensional-derived bone surface representations. This approach largely outperforms the manual planning practice based on two-dimensional dental computerized tomographic images printed or on film.

Computer Simulation↗
PubMedDate not supplied

The relationship of some histologic parameters, radiographic evaluations, and Periotest measurements of oral implants: an experimental animal study.

The objective of this study was to analyze the efficacy and correlation between clinical and histologic parameters used to evaluate oral implants. After extraction of the premolars and a healing time of 4 months in 16 Dutch goats, four Brånemark implants were placed in the maxillary left and right premolar regions. After a healing time of 6 months, followed by another 4 months with the permucosal abutments, the goats were sacrificed and the jaws were block-resected. Before histologic preparation, long-cone radiographs were made and Periotest scores of the implants were recorded. Bone level measured histomorphometrically were found to be 0.85 mm more apically, compared to that measured radiologically (P = .001). Furthermore, statistically significant correlations (P > 0.2) were not found between the Periotest values of the calcium-phosphate-coated and uncoated implants for (1) the first thread in contact with bone, or (2) with the total number of threads in contact with bone. It was concluded that the radiologic data overscored the real marginal bone level around screw-shaped oral implants, and that the Periotest device is neither able to discriminate between the first thread nor between the total number of threads in contact with bone.

Animals↗