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Biomedical subjects

M Quirynen

Publications and source records attributed to M Quirynen.

At least 109 records · Page 6Linked to original sources
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↗
PubMed1991

Discriminating power of five plaque indices.

Since plaque plays a major role in the development of periodontal inflammation, special attention is paid to its composition and quantity. Several indices have been designed for the quantification of the supragingival plaque. The aim of the present study was to compare the utility and discriminating power of five such plaque indices. In 14 subjects, three teeth were selected randomly on which the undisturbed plaque formation was studied over a period of 96 hours. This examination was performed twice, the first time after induction of gingivitis and a second time starting with a healthy gingiva. It is known that in the presence of gingival inflammation, the plaque growth rate slightly increases. Plaque formation was estimated at several visits with the following indices: Harrap index, Quigley and Hein index, Navy index modified by Clemmer and Barbano, Navy index modified by Hancock and Wirthlin, and a planimetrical plaque scoring system. The path of the plaque growth curve was found to depend on the selected plaque index, going from an exponential curve (planimetry) over an sigmoidal curve (Harrap index, Navy index modified by Hancock and Wirthlin) to a nearly linear relation (Quigley and Hein, Navy index modified by Clemmer and Barbano). By comparing the plaque scores on patients with healthy gingiva with those from patients with inflamed gingiva, it was found that the planimetrical plaque index had a clearly higher discriminating power. It was concluded that the choice of an index for the measurement of the plaque extension depends on the goals of the study.

Adult↗
PubMed1991

The influence of gingival inflammation, tooth type, and timing on the rate of plaque formation.

The undisturbed supragingival plaque formation was recorded twice over a 100 hours period in 14 healthy dental students; first after induction of gingival inflammation and a second time starting from a healthy gingiva. During each experimental segment plaque formation was recorded on 42 randomly selected and clean teeth at the start and after 6, 12, 24, 30, 36, 48, 54, 60, 72, 84, and 96 hours. Four hours later all teeth up to the first molars were examined. The presence of disclosable plaque was calculated planimetrically as percent of the total labial surface area of the tooth. The rate of plaque formation was found to be significantly greater (P = 0.001) in the presence of gingival inflammation (+ 29.0%). Moreover, this study indicates an important variation in the plaque growth rate within the dentition; the highest scores were found for the upper premolars, the upper molars, and the lower front teeth. Finally, the rate of plaque formation was found to decrease during the night.

Adult↗
PubMed1991

Periotest: an objective clinical diagnosis of bone apposition toward implants.

Implant mobility as an indicator of failing close bone apposition is generally known. Whereas a clearly visible mobility can always be correlated with an interposition of soft tissue, the range from a clinically firm implant to just tangible implant mobility represents the actual problem zone. Thirty consecutive patients who had mandibles restored with osseointegrated implants ad modum Brånemark were tested with the Periotest device for damping characteristics of the implants and the peri-implant tissues as a whole. The mean Periotest value (PTV) was -1.74. The characteristics of the mandible, the peri-implant tissue, and the abutment length are the determining factors for the PTV. Fixture length, dolder bar, and length of time in function had no significant influence on the PTV.

Adult↗
PubMed1990

Distribution of bacterial morphotypes around natural teeth and titanium implants ad modum Brånemark.

The subgingival plaque around both teeth and implants was analysed by means of differential phase-contrast microscopy. It was noted that, in comparison to natural teeth, the subgingival samples from implants were more frequently too small to provide adequate bacterial counts. In 24 partially edentulous patients (with implants and teeth in the same jaw), no significant differences in the distribution of bacterial morphotypes could be found between implants and natural teeth. The %s of coccoid cells, motile rods, spirochetes and other bacteria were 65.8, 2.3, 2.1, and 29.8 for implants and 55.6, 4.9, 3.6, and 34.9 for teeth, respectively. However, when the plaque composition on the implants of fully edentulous patients was compared with those of teeth or implants of partially edentulous patients (with teeth and implants in the same and/or opposite jaw), significant differences appeared. In fully edentulous patients, more coccoid cells (71.3%) and significant fewer motile rods (0.4%) and spirochetes (0.0) were found around the implants. The results suggest that teeth may serve as a reservoir for the bacterial colonisation of titanium implants in the same mouth.

Dental Implants↗
PubMed1990

Computed tomography in the preoperative planning of oral endo-osseous implant surgery.

Computed tomography (CT) is a well-established aid in the preoperative assessment of the dimension of mandible and maxilla for endo-osseous implant installation. CT is a valuable tool for the measurement of the alveolar ridge and recognition of the course of the inferior alveolar nerve canal. In the present study, three different techniques were examined: normal CT images with coronal and sagittal slices, standard reconstructions based on axial slices, and multiplanar reconstruction and display (MPR/MPD), also based on axial slices. Six dissected human jaw bones were examined with these three techniques. Afterwards, these jaws were sawn, and the real values were measured. Comparing these scores with the radiological measurements, the standard reconstruction technique seemed the most reliable method in the preoperative examination of the jaw bone quality and bone proportion.

Dental Implantation, Endosseous↗
PubMed1990

Comparative antiplaque activity of sanguinarine and chlorhexidine in man.

This clinical investigation examined the effect of a sanguinarine extract on bacterial plaque growth in man. Three different mouthrinses were examined: (i) Veadent containing 0.03% sanguinarine and 0.2% zinc chloride (test rinse); (ii) a vehicle solution containing all the excipients of Veadent except the 0.03% sanguinarine (control rinse); (iii) Hibident a 0.2% chlorhexidine digluconate formulation (positive control rinse). The trial in which 12 dental students participated, was designed as a single-blind, cross-over study. During 3 experimental periods of 18 days, the participants refrained from mechanical oral hygiene and rinsed twice a day with one of the above mentioned solutions. Between experimental phases, a wash-out period of 11 days was instituted. In each subject, 4 teeth were randomly selected for assessment. Clinical evaluations were performed at days 1 (0, 4, 8, 12 hours), 2, 4, 11 and 18. The plaque on the buccal surfaces of the selected teeth was disclosed with neutral red 0.05% and colour slides taken. The % of the tooth surface covered with plaque was calculated planimetrically from these colour slides. The present results show an excellent anti-plaque effect with Hibident, a very small effect with Veadent and a negligible effect with the vehicle solution without the sanguinarine. These findings would suggest that the Veadent mouthrinse would have at most only a limited role as a plaque inhibitor.

Adult↗
PubMed1990

The influence of surface free energy and surface roughness on early plaque formation. An in vivo study in man.

Previous in vivo studies suggested that a high substratum surface free energy (s.f.e.) and an increased surface roughness facilitate the supragingival plaque accumulation. It is the aim of this clinical trial to explore the "relative" effect of a combination of these surface characteristics on plaque growth. 2 strips, one made of fluorethylenepropylene (FEP) and the other made of cellulose acetate (CA) (polymers with surface free energies of 20 and 58 erg/cm2, respectively) were stuck to the labial surface of the central incisors of 16 volunteers. Half the surface of each strip was smooth (Ra +/- 0.1 microns) and the other half was rough (Ra +/- 2.2 microns). The undisturbed plaque formation on these strips was followed over a period of 6 days. The plaque extension at day 3 and 6 was scored planimetrically from color slides. Finally, of 6 subjects samples were taken from the strips as well as from a neighbouring smooth tooth surface (s.f.e. 88 erg/cm2; Ra +/- 0.14 microns). These samples were analysed with a light microscope to score the proportion of coccoid cells, and small, medium, and large rods or fusiform bacteria. At day 3, a significant difference in plaque accumulation was only obtained when a rough surface was compared with a smooth surface. However, at day 6, significantly less plaque was recorded on FEP smooth (19.4%) when compared with CA smooth (39.5%). Between FEP rough (96.8%) and CA rough (98.2%), no significant difference appeared.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1990

CT scan standard reconstruction technique for reliable jaw bone volume determination.

Computed tomography can assist the surgeon in planning the exact three-dimensional positioning of endosseous implants in the jaw bone. This study examined the reliability of three CT techniques: direct imaging (normal coronal and sagittal slices), standard reconstruction (based on axial slices), and multiplanar reconstruction and display (also based on axial slices). The three imaging techniques were used to estimate the bone height, bone width, and maximal implant length in six dissected human jaw bones. These jaws were then sawed perpendicular to their axis to enable measurement of real values for comparison. The sagittal and coronal slices frequently were overestimated, especially in the canine and premolar regions. The mean absolute deviation was 1.4 mm. Standard reconstruction offered the most reliable cross-sectional images, with a mean absolute deviation of 0.5 mm. The multiplanar reconstruction and display technique frequently demonstrated underestimations (mean absolute deviation was 2.3 mm). The standard reconstruction technique seems to be the method of choice in preoperative radiographic examination of patients before implant placement.

Alveolar Process↗
PubMed1990

[Osseointegrated implants ad modum Brånemark in the oral rehabilitation of patients with advanced periodontal breakdown].

Despite the achievements of modern periodontology, partially or completely edentulous mouths are unavoidable. The rehabilitation of such patients is a great challenge in oral health care. The state of the art of osseointegrated implants according to Brånemark is described. Both full dentures and fixed partial dentures are discussed, with special emphasis on microbiological issues. The hypotheses are supported by substantial published evidence, and the problems discussed are further exemplified by a number of clinical case reports. The authors conclude that osseointegration according to Brånemark is an effective long-term method for oral rehabilitation, and that the failure rate is low. One reservation that has to be made is that we are still waiting for the results of long-term studies on patients who are edentulous due to advanced adult periodontitis. This is the only way to evaluate in more detail the robustness of the tissues around the implantation site.

Dental Implants↗
PubMed1990

[The implant/tissue interface in a clinical perspective].

For a proper insight in the implant/tissue interface of permucosal oral implants it is good to refer to the tooth/periodontium interface. Although there are evident differences such as the lack of a periodontal ligament with its possibilities for eruption and migration and elaborate neural endings, it seems that classical periodontal parameters are the yardstick to discriminate failure from success of oral implants. Long cone radiographs and mobility assessment seem the only available clinical tools to detect a scar tissue interposition. On the other hand, their discrimination power is insufficient to prove close bone apposition. Further studies are needed to interpret the observations that around failing implants the subgingival microflora resembles that of active adult periodontitis. Periodontologists can learn a lot from the implant/periodontium interface to get a better understanding of the tooth/periodontium complex.

Dental Implants↗
PubMed1989

Is early plaque growth rate constant with time?

Early plaque growth and plaque topography were studied in 15 young adults with a healthy periodontium during a 4-day period of no oral hygiene. After perfect tooth-cleaning, the recolonisation of the buccal surfaces of 48 teeth (front teeth and premolars) was recorded at the start and after 6, 12, 24, 30, 36, 48, 54, 60, 72, 84 and 96 h. At each visit, reproducible colour slides of the buccal tooth surfaces were taken after plaque disclosure. Plaque extension was calculated planimetrically as a % of the total surface area of the tooth. At the end of the experimental period, an average of 27.7% of the surface area was covered by plaque. The early plaque growth followed an exponential curve with a slight tendency for saturation at 96 h. During the night, the plaque growth rate decreased by up to 50%. Clear differences in plaque growth rate were observed between types of teeth, and the plaque growth pattern seemed to be closely correlated to irregularities of the tooth surface. The discontinuity in plaque growth and the influence from the tooth surface roughness have important implications for oral hygiene planning.

Adult↗
PubMed1989

The influence of surface free-energy on planimetric plaque growth in man.

The purpose of this study was to examine the change in plaque area over nine days in vivo on four materials with different surface free-energies (s.f.e.). Twelve healthy dental students participated in a cross-over, split-mouth, double-blind study. Supragingival plaque formation was recorded over a nine-day period, on four different materials: fluorethylenepropylene (Teflon) (FEP), parafilm (PAR), cellulose acetate (CA), and enamel (E) with s.f.e. of 20, 26, 57, and 88 erg/cm2, respectively. Strips made from the first three materials were stuck to the buccal surface of an upper incisor. The remaining incisor was carefully polished and served as an enamel surface. The increase in plaque was evaluated after three, six, and nine days. A planimetrical analysis was used so that the plaque area could be expressed as a percentage of the total buccal tooth surface. This procedure was repeated on each subject, so that at the end, each pair of central or lateral incisors received the four tested materials. The results indicated that the adherence of micro-organisms on pellicle-coated substrata was influenced by the material's s.f.e.; there was an association between the s.f.e. of the substrata and the supragingival plaque extension in vivo. High surface free-energy substrata in the oral cavity attracted more micro-organisms than did low energetic materials. Additionally, the bacterial adhesion seemed very weak on surfaces with a low s.f.e.

Adult↗
PubMed1989

[Surgical and non-surgical approach to deep periodontal pockets].

Deepened pockets are a challenge because they offer an anaerobic niche and because of their inaccessibility to personal plaque control measures. Scaling and root planing followed by regular professional plaque removal are effective in arresting the progress of most chronic adult periodontitis. Only when pockets remain inflamed after repeated thorough professional treatment during several months can a surgical pocket elimination technique be used. The results will depend on the type of attachment loss (horizontal vs. irregular) the root anatomy (furcations) and the training level of the operator, general practitioner or periodontologist. There is an increasing trend in the anterior parts of the oral cavity (monoradicular teeth easily accessible for plaque control) to use the Widman technique. Long-term data concerning the stability of this new attachment are lacking. Gingivectomy is less elaborate, does not imply a high-level sterile environment like for mucoperiosteal flap surgery, but leads to phonetic and esthetic side-effects when used in frontal areas. In the distal areas the apically displaced and the shortened repositioned flap techniques are effective in a long-term perspective if regular postoperative monitoring is respected. Discussion remains concerning the stability of a new connective tissue attachment vs. a long epithelial attachment. A recent breakthrough is the so-called Guided Tissue Regeneration where by means of a submucosally membrane the periodontal ligament cells are allowed to regenerate the different periodontal tissue compartments. Preliminary results are very encouraging but need further evaluation.

Dental Plaque↗