PubMed Health⌕ Search

Biomedical subjects

L Dermaut

Publications and source records attributed to L Dermaut.

At least 19 recordsLinked to original sources
PubMed2001

Revascularization after cryopreservation and autotransplantation of immature and mature apicoectomized teeth.

Autotransplantation of immature teeth can have a success rate of almost 98% if the tooth is atraumatically transplanted from the donor site to a suitable acceptor site and the extraoral time is kept to a minimum. When the tooth cannot be transplanted immediately, cryopreservation and storage in a tooth bank offer new possibilities for autotransplantation. However, the effect of cryopreservation on the revascularization of transplanted teeth is still unknown. The purpose of this study was to examine revascularization in immature teeth that have an open apex and in mature teeth that have had the apex cut. The study was carried out on 16 teeth in 2 dogs; 8 teeth were removed and immediately transplanted to the contralateral position and 8 teeth were cryopreserved and transplanted 1 week later. The results show that: (1) teeth can revascularize after autotransplantation if the original pulp tissue is removed at the time of extraction, (2) there is no significant difference in the amount of revascularization between teeth stored in a tooth bank for 7 days and those immediately transplanted without freezing, and (3) there is no difference in the ingrowth of new pulpal tissue between mature apicoectomized teeth and immature teeth.

Angiography↗
PubMed2000

The effect of tooth size discrepancy on occlusion: An experimental study.

The purposes of this experimental study are the following: (1) to compare the anterior and overall tooth size ratios reported by Bolton to values reported in epidemiologic studies, (2) to assess the accuracy of tooth size discrepancy measurements, (3) to investigate to what extent generalized tooth size discrepancy affects occlusion, (4) to investigate the effect of leveling the curve of Spee, and (5) to evaluate the effect of extraction therapy of 4 premolars on occlusion. For the first part of the study, Bolton's mean anterior and overall tooth size ratio (as well as the extraction values) were compared with calculations derived from 4 publications reporting mean mesiodistal tooth width by using the t test (P </=.05). The second part of the study was carried out on a setup made from 1 dental cast of a male patient judged to have an ideal occlusion at the end of a nonextraction treatment. Our data reveal (1) no significant difference between the overall tooth size ratios of the Bolton values compared to 4 studies, but the anterior ratios were significantly different, (2) high reproducibility (99%) of tooth size discrepancy measurements, (3) that severe tooth size discrepancy affects the occlusion only a little, (4) that an excessive (6 mm) curve of Spee creates the poorest setup result, and (5) that extraction therapy only slightly affected the final occlusion. The effect of generalized tooth size discrepancy appears to be limited.

Dental Occlusion↗
PubMed1999

Stability of implants as anchorage for orthopedic traction.

The aim of this animal study was to investigate the stability of osseointegrated fixtures when used as anchorage for orthopedic traction with extreme force magnitude. Three Brånemark fixtures were placed in the left zygomatic arch and three in the right of five adult dogs. An orthopedic nonaxial force of 5 N was applied using an intraoral coil system. The initial displacement immediately after force application was measured by means of speckle interferometry. After 2 months of continuous loading, bone adaptation and mineralization around all implants were analyzed. All the loaded implants were immobile. Significant marginal bone loss at the abutment-fixture interface (<1 mm) was observed around each loaded fixture implant. Bone remodeling was significantly more pronounced at the tension side of the implants, irrespective of fixture length. Radiographical and histological analyses showed bone with normal trabecular pattern around the implants.

Adaptation, Physiological↗
PubMed1999

The effect of tooth position on the image of unerupted canines on panoramic radiographs.

The purpose of this study was to evaluate whether panoramic tomograms, which are routinely used in orthodontic practice, can provide adequate information to localize an impacted canine. The effect of changes in position and inclination of an impacted canine on orthopantomograms was investigated in an experimental set-up. An upper canine was removed from a human skull and replaced in a positioning system, enabling simulated positional variations in impactions. In comparison with the image of a contralateral well-aligned canine, the length of the impacted tooth always decreased or remained unchanged, whereas the tooth width increased or remained unchanged. The angulation of the image was unaffected by varying the position of the impacted canine, but altered when the inclination of the tooth in a sagittal or frontal direction was changed. If there was any transversal shift of the impacted canine on the orthopantomogram, it was always towards the mid-sagittal plane. The curvature of the tooth increased after dorsal inclination and decreased after ventral inclination (in comparison with the contralateral well-aligned canine).

Cephalometry↗
PubMed1998

Incisor torque by means of a modified Teuscher activator. Three case reports.

It is generally accepted that in the treatment of Class II, 1 malocclusion classical activators may tip the upper incisors considerably. In comparison, in the cases described, an even better torque control was obtained. It has been our clinical experience that with the modified Teuscher activator it is possible to control upper incisor inclination and in some cases it is even possible to induce active palatal root torque. The appliance is relatively comfortable with good vertical retention even without headgear.

Activator Appliances↗
PubMed1997

The importance of humidity in the in vitro study of the cranium with regard to initial bone displacement after force application.

The aim of this pilot study was to find a suitable model for simulating in vivo initial displacements of the maxilla after force application. Force was exerted on the maxillae of four dogs by means of a dental splint. To register the bone displacement, speckle interferometry was used as the measurement technique. The initial orthopaedic effect as a result of force application in vivo was registered by the construction of rotation centres around which the maxilla rotated. The orthopaedic effect after force application in vivo was compared with different in vitro situations of the laboratory animal. After the animal had been killed and its maxilla macerated, the cranium was placed in a sealed conditioned box. Only three skulls were found to be suitable for this experiment. The environment thus created can be influenced by changes in relative humidity. Various forces were applied in various directions on the maxilla of three Alsatians. By changing the relative humidity, an attempt was made to create a situation in which the initial bone displacements after force application were comparable to the in vivo situation. None of the laboratory animals used showed a comparable condition for the in vivo situation through manipulation of relative humidity. As only three dogs were experimented on, these findings are tentative. This experiment will be extended to three more dogs from the same litter.

Animals↗
PubMed1994

Infrared laser and bone metabolism: a pilot study.

A circular defect in each parietal bone of six Wislander rats was created. The animals were divided into two three-unit subgroups. The experimental group received infrared laser radiation on the left defect. The control group was sham irradiated. After 28 days, the bone metabolism was evaluated by technetium-99m methylene diphosphonate scintigraphy. The obtained results revealed no differences in bone metabolic activity between the laser-treated and the control defects.

Animals↗
PubMed1994

[Orthopedics in orthodontics: fiction or reality? Literature review].

The purpose of this literature review is to investigate the orthopedic effect of functional appliances as activators. Herbst appliances and extraoral traction appliances. The matter on correction of skeletal Class II discrepancies in growing children remains controversial despite extensive research. However most authors agree on the fact that major contributions derive from dento-alveolar changes rather than from skeletal ones. Nevertheless, the authors of this review want to emphasize that the discussed Class II orthopedic appliances have an important value in clinical orthodontics. Due to scientific evidence, their orthopedic effect however, must be questioned so far.

Activator Appliances↗
PubMed1992

Comparison in shear bond strength of orthodontic brackets between five bonding systems related to different etching times: an in vitro study.

New adhesives are continuously being marketed. The adhesive-bracket bond is still the weakest point in orthodontic bonding. A new device for the measurement of shear bond strength values (SBS) of orthodontic brackets is presented in this article. With this device, five commercial products were evaluated for their SBS: Lee Bond (LB), Concise (C), Super C (SC), Achieve-no-mix (ANM), and Panavia Ex (PE). After applying Begg brackets of laminated minimesh on lower human incisors, the specimens were thermocycled. The products investigated produced high bond strengths. The products tested showed shear bond strengths that were significantly lower than those stained with PE. The application of PE yielded the highest shear values. Nevertheless, some characteristics of this product might be clinically somewhat inconvenient. There was no significant difference in shear bond strength between 15 and 60 seconds enamel etching before bond application.

Acid Etching, Dental↗
PubMed1990

The value of the macerated skull as a model used in orthopaedic research.

In this study a method was developed to enable the measurement of initial bone displacement in vivo, post-mortem, and in vitro. Speckle interferometry was used as measuring technique. Through the construction of the centres of rotation, the different orthopaedic effects could easily be compared. Also the magnitude of the bone displacement could be calculated. The initial post-mortem displacement of the maxilla corresponds very well with the initial in vivo displacement. After maceration and drying of the skull, however, clear differences from the in vivo displacement were found. The orthopaedic effects on a macerated skull can be manipulated considerably by changing, for instance, the degree of humidity. Only a limited number of skulls was examined in these experiments and probably still other variables exert an influence on the bone displacement in the macerated skull. Nevertheless, it is certain now that the dry skull cannot reliably be used as a model to simulate the initial bone displacement in vivo. The experimental set-up of this study will be used in the future to evaluate the effect of environmental factors (humidity, temperature, etc.) in an attempt to improve the value of the skull as a model for orthopaedic research. Moreover, this technique permits investigation of the link between initial displacements in vivo and longitudinal changes.

Aging↗
PubMed1990

[Rapid maxillary suture expansion].

Rapid maxillary expansion is a technique with an old but controversial history. Bio-mechanics and apparatus have largely involved over the years and the procedure is generally accepted. Discussion concerns only the patient age range on which the therapy is applicable. Fourteen to eighteen seems the accepted age limit. Three essential parameters determine the success of the expansion: degree of interlocking, synostosis and skeletal resistance from the surrounding osseous tissues.

Adolescent↗
PubMed1989

[Dental autograft: a supplementary dimension in dental practice].

This article deals with the possibilities and limitations of autogenous transplantations. In properly selected cases (trauma, missing teeth,...), this procedure might be a valuable alternative treatment. The indications for transplantation, the surgical technique, the recipient site and the choice of the transplant are discussed. The most important parameters which influence the success of a transplantation are: the stage of root formation, the atraumatic removal and insertion of the germ, the final position of the transplant and the post-operative fixation. Clinical examples will illustrate some indications.

Child↗