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Biomedical subjects

D van Steenberghe

Publications and source records attributed to D van Steenberghe.

192 records · Page 11Linked to original sources
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 At 3 years, 150 implants remained submerged and 66 implants had been withdrawn because the subjects discontinued study participation.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

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

Treatment of fenestration and dehiscence bone defects around oral implants using the guided tissue regeneration technique: a prospective multicenter study.

Four clinical centers, using the Brånemark System and with personnel trained in the use of Gore-Tex Augmentation Material (GTAM), participated in a prospective study of 45 patients 18 to 83 years of age. A total of 55 implants were placed with membranes because of local bony defects (fenestration or dehiscence). Dehiscence and fenestration defects were evaluated as one group. The mean initial defect height was 4.7 mm (SD = 3.0). After healing, the remaining defect height was reduced to 1.1 mm (SD = 2.3). The decrease in surface exposure was significant. Complications were primarily attributed to exposure of six membranes during the early healing period. The cumulative survival rate was 84.7% in maxillae and 95.0% in mandibles after 2 years of follow-up. The surgical application of GTAM to produce bone in localized bony defects around oral implants seems to be a predictable method that may reduce the need for extensive augmentation surgery in patients with insufficient jaw bone volume.

Adolescent↗
PubMedDate not supplied

Qualitative evaluation of the masseteric poststimulus EMG complex following mechanical or acoustic stimulation of osseointegrated oral implants.

To qualify the contribution of the periodontal-ligament receptors to trigeminal inhibitory reflex responses, 20 subjects with maxillary implant-supported fixed prostheses opposing mandibular teeth or implants were compared to 10 subjects with removable dentures in the maxilla opposing implant-supported prostheses and 10 subjects with natural teeth in both jaws. Standardized mechanical taps were delivered to an implant, a denture tooth, or a natural tooth in the central incisor region of the maxilla. Bilateral surface electromyographic recordings of the masseter muscles were obtained while subjects maintained a constant myoelectric activity by clenching. Stimulation of an implant in partially edentulous subjects elicited a reflex response in 7 of 10 subjects. Likewise, stimulation of a tooth of a maxillary removable denture resulted in a clear reflex response in 5 of 10 totally edentulous subjects. On the other hand, a reflex response did only occur in 1 of 10 totally edentulous subjects with implant-supported prostheses in both jaws. It was concluded that the presence of some natural teeth in either the maxilla or mandible allowed the occurrence of a reflex response. In totally edentulous subjects, mucosal or periosteal mechanoreceptors, triggered by stimulation of the denture bearing area or by transmission of vibrations through the jaw bone, could be responsible for the remaining reflex responses.

Acoustic Stimulation↗
PubMedDate not supplied

The use of e-PTFE barrier membranes for bone promotion around titanium implants placed into extraction sockets: a prospective multicenter study.

This multicenter study was conducted to determine the predictability for implants placed into immediate extraction sockets and augmented with e-PTFE barrier membranes. Forty-nine implants were placed in immediate extraction sockets. Initial and final defect measurements and the number of threads exposed were compared. Patients were followed up to 1 year after implant loading. Three implants were lost at the abutment connection surgery. The 1-year survival rate was 93.9%. Twenty barrier membranes became exposed and were removed prior to stage 2 surgery, while the remaining barriers were removed at abutment connection. The average defect bone formation for membrane-retained sites was 4.8 mm, while the average bone formation for sites in which the membranes were prematurely removed was 4.0 mm (P < .0001). At stage 2 surgery there was an average of 0.6 threads exposed (P < .001) for the membrane-retained sites and 2.6 threads for the early removal sites (NS). Forty-five pairs of nonstandardized radiographs were evaluated for bone loss after implant loading (average 7.5 months). The mesiodistal bone loss averaged 0.72 mm. Within the limits of this study, e-PTFE membranes will promote clinically and statistically significant amounts of bone around immediately placed implants. Retention of e-PTFE barriers until stage 2 surgery improves the amount of bone promoted around the implants.

Adult↗
PubMedDate not supplied

Comparison of surface characteristics of six commercially pure titanium abutments.

Clinical studies have reported a positive correlation between the surface roughness of teeth or implants and the rate of supragingival and subgingival plaque maturation. This study compared the surface characteristics of abutments from different implant systems (Astra Tech, Bonefit, Brånemark, Core-Vent, IMZ, and Steri-Oss). For each system, two abutments were examined for surface roughness and surface hardness. The latter served as an indicator for resistance against roughening during professional or habitual oral hygiene procedures. The Ra values (in microns) of the tested abutments were: Steri-Oss, 0.10; IMZ, 0.14; Brånemark, 0.21; Bonefit, 0.23; Astra Tech, 0.27; and Core-Vent, 0.30. The Vickers hardness scores (in VHN) were: Brånemark, 154; IMZ, 208; Astra Tech, 258; Bonefit, 292; Core-Vent, 304; and Steri-Oss, 340. In comparison to most metallographically polished composites, titanium abutments showed a higher initial surface roughness and a slightly higher surface hardness. This may explain, besides the known high surface free energy of titanium, rapid plaque growth on these abutments.

Dental Abutments↗
PubMedDate not supplied

The influence of titanium abutment surface roughness on plaque accumulation and gingivitis: short-term observations.

The roughness of intraoral hard surfaces plays an important role in bacterial adhesion and colonization. Earlier studies have shown that rough surfaces accumulate up to 25 times more subgingival plaque than do smooth sites. In the present study, the influence of surface smoothing was studied. In six partially edentulous patients waiting for a fixed prosthesis supported by endosseous titanium implants, four titanium abutments with different surface roughness were randomly placed. After 1 month of intraoral exposure, subgingival plaque samples from each abutment were compared within each patient by means of differential phase-contrast microscopy. After 3 months, supragingival and subgingival plaque samples were taken from all abutments for differential phase-contrast microscopy and culturing. Probing depth, recession, and bleeding upon probing were scored at the same visit. Differential phase-contrast microscopy showed that subgingivally, only the two roughest abutments harbored spirochetes after 1 month. After 3 months, subgingivally, the composition of the flora showed little variation on the different abutment types, although spirochetes were only noticed around the roughest abutments. Anaerobic culturing resulted in comparable amounts of colony-forming units for all abutment types, both supragingivally and subgingivally. Subgingivally, the microbiologic composition did not show major interabutment differences. Clinically, small differences in probing depth were observed. The roughest abutment showed some attachment gain (0.2 mm) during 3 months, whereas all other abutments had an attachment loss ranging from 0.8 to greater than 1 mm. The results indicate that a reduction in surface roughness (less than a roughness of 0.2 micron) had no major effect on the microbiologic composition, supragingivally or subgingivally. These observations indicate the existence of a threshold roughness below which no further impact on the bacterial adhesion and/or colonization should be expected. However, clinical evaluation seems to indicate that a certain surface roughness is necessary for increased resistance to clinical probing.

Bacteria, Anaerobic↗
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

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↗