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Biomedical subjects

J A De Boever

Publications and source records attributed to J A De Boever.

18 recordsLinked to original sources
PubMed1990

[Occlusion, articulated and articulation].

In this paper the so-called 'normal' or 'ideal' occlusal relationships are described in static centric as well as in dynamic, eccentric positions. However, difference is made between the different occlusal concepts. There is no real antagonism between the 'physiologic occlusal concept' in natural dentition and the 'therapeutic occlusal concept' on which the treatment should be based in restoring the occlusion. The different forms of occlusion and articulation found in the natural dentition are the expression of physiologic, biological variations. The rest position of the mandible is an unreliable reference point in occlusal rehabilitation. Moderate attrition in older patients should not be considered as pathologic and there is no indication for treatment in absence of functional pathology.

Aging↗
PubMed1990

[Fixed restorations of a dentition with reduced periodontal support in partially edentulous patients].

Placing restorations in patients who have a limited number of teeth and reduced periodontal support is no longer controversial, given careful selection of patients, preprosthetic periodontal treatment, and a thorough maintenance program. In this paper, attention is drawn to general prosthetic planning, including the use of long-span bridges. Because of increased tooth mobility, cross-arch stabilization of the bridges with interlocks or with postsolder connections is advocated. The framework should be rigid enough to avoid deflection of the bridges. Preparation of the vital and nonvital abutment teeth needs much attention. To avoid using a removable prosthesis, a cantilever bridge can be used, but it makes the construction more prone to fracture. A number of periodontal-prosthetic patients demonstrate a "posterior collapsed bite." Rehabilitation requires the restoration at a "new" vertical dimension of occlusion. This can be done, without functional hazards, in a one-step clinical procedure. A long functional adaptation period is unnecessary. The treatment outcome of furcations is not always predictable. Therefore, hemisection or amputation are often the treatments of choice. On these hemisected roots, bridges can be made and successfully maintained. Finally, it should be stressed that not all teeth have to be replaced: a premolar, shortened-arch occlusion is often sufficient for adequate function.

Denture Design↗
PubMed1989

[Occlusal status and disordered functions. Epidemiologic study of children aged 3 to 6 years in West Flanders].

This study is a part of larger epidemiologic survey done on 504 children, aged 3 to 6 years. The results of the occlusal parameters, and more specially, the relationship between occlusion and parafunction, as there are fingersucking and dummysucking, were analysed and discussed. The examined occlusal parameters were crossbite, open bite, attrition and incisor/molar and lateral movements.

Belgium↗
PubMed1988

Bacterial invasion in root cementum and radicular dentin of periodontally diseased teeth in humans. A reservoir of periodontopathic bacteria.

In this study the viability and the distribution of bacteria within the radicular dentin and pulp of periodontally diseased caries-free teeth were studied. Healthy teeth served as controls. Samples were obtained from the pulp tissue and from the radicular dentin. Dentin samples were taken from the interdental surfaces in the subgingival area. Starting from the pulpal side, three to five successive dentin layers of approximately 1 mm thickness were sampled. The samples were processed and cultured using an anaerobic technique. Bacterial growth was detected in 87% of the periodontally diseased teeth. In 83% of the teeth, bacteria were present in at least one of the dentin layers. Fifty-nine percent of the diseased teeth, from which the pulp tissue was cultured, contained bacteria in the pulp samples. The mean bacterial concentrations in the pulp and dentin layers ranged from 1,399 to 16,537 colony-forming units (CFU) per mg of tissue. These concentrations were 259 to 7,190 times greater than concentrations found in healthy teeth. It is suggested that the roots of periodontally diseased teeth could act as bacterial reservoirs from which recolonization of mechanically treated root surfaces can occur, as well as infection of the dental pulp. These findings might change current concepts concerning root surface debridement in periodontal therapy.

Actinomyces↗
PubMed1988

Ultrastructural observations on bacterial invasion in cementum and radicular dentin of periodontally diseased human teeth.

In this study the bacterial invasion in root cementum and radicular dentin of periodontally diseased, caries-free human teeth was examined. In addition, structural changes in these tissues, which could be related to the bacterial invasion, were reported. Twenty-one caries-free human teeth with extensive periodontal attachment loss were studied by light and scanning electron microscopy. At the base of the gingival pocket, bacteria were found in the spaces between remnants of Sharpey's fibers and their point of insertion in the cementum. In teeth that had been scaled and root planed, most of the root cementum had been removed. Bacterial invasion was found in the remaining root cementum. The invasion seemed to start as a localized process, often involving only one bacterium. In other areas bacteria were present in lacunar defects in the cementum. These lacunae extended into the radicular dentin. In 11 teeth bacteria had invaded the dentinal tubules. Most bacteria were located in the outer 300 microns of the dentinal tubules, although occasionally they were found in deeper parts. In two of the nontreated teeth, bacteria were detected on the pulpal wall. No correlation was found between the presence of bacterial invasion and the absence of radicular cementum. No bacteria were found in the portion of the root located apically to the epithelial attachment. These data are in agreement with our results from cultural studies of the bacterial flora in these structures. It was also demonstrated that in spite of meticulous scaling and root planning and personal oral hygiene, bacterial plaque remained present on radicular surfaces. Both the invaded dentinal tubules and the lacunae could act as bacterial reservoirs from which recolonization of treated root surfaces occurs. From these reservoirs bacteria could also induce pulpal pathoses. Since these bacterial reservoirs are not eliminated by conventional mechanical periodontal treatment, it seems appropriate to combine mechanical periodontal therapy with the use of chemotherapeutic agents.

Bacteria↗
PubMed1987

Scanning electron microscopy of dentin caries. Experimental in vitro studies with Streptococcus mutans.

This study was performed to gain better insight into the mechanisms involved in carious destruction of human dentin by Streptococcus mutans. In particular, bacterial colonization of dentin surfaces and bacterial invasion in dentin were studied. Streptococcus mutans (S. mutans), strain NCTC 10449, was grown on sterile dentin blocks in a 10% CO2 atmosphere at 37 degrees C. After 72, 120, 144 and 288 h of incubation the specimens were processed for scanning electron microscopic examination. The colonization of the dentinal surface progressed slowly and was nearly complete after 288 h. Invasion of S. mutans into the dentinal tubules was found occasionally and was limited to the initial 5 micron of the tubular lumen. The acid metabolites produced by S. mutans, caused lesions of the dentinal structures in the close proximity of the bacteria. From the results of this in vitro study it appears that carious destruction of exposed dentinal surfaces by S. mutans mainly occurs at the exposed dentin after it has been colonized by bacteria. Destruction of the deeper dentinal layers by bacteria invading the dentinal tubules may play a less important role. However, in the few cases where S. mutans invaded the dentinal tubules, rapid destruction of the peritubular dentin sheath occurred. In addition, the possibility remains that acid metabolites produced by S. mutans diffuse into the dentinal tubules and cause tissue damage in the deeper parts of the dentin.

Dental Caries↗
PubMed1984

Epidemiologic survey of functional conditions of the masticatory system in Belgian children aged 3-6 years.

In this epidemiologic survey 510 children aged 3-6 yr were investigated. Several occlusal and functional parameters were measured: the maximal interincisal distance, the frequency of lateral and frontal crossbite, open bite, the number of tooth contacts on lateral excursions of 3 mm, the wear facets, deviations in opening, pain in muscles and in the TM-joints, TMJ sounds, parafunctional habits. The interincisal distance varied between 25 and 55 mm. This distance increased with age. Only five children had a hypermobility of the mandible (opening more than 55 mm) and 11 a restricted opening movement (less than 30 mm). 7.2% showed a lateral crossbite on the right, and 8.9% on the left, side. The percentage of an open bite decreased with age from 66.7% in the 3-yr-olds to 20.0% in the 6-yr-olds. 33% of the children had only one contact on the working side. As reported by the parents 7.7% had regularly bruxism but 21.8% showed wear facets on the molars and 40.7% on the front teeth. Only in three girls were the TMJ painful to palpation. Dysfunction only occurred in 3.5% of the sample.

Belgium↗
PubMed1983

Occlusal relationship in patients with pain-dysfunction symptoms in the temporomandibular joints.

A total of 135 patients (thirty-three males, 102 females) seeking treatment for pain and dysfunction of the TMJ were divided into five subgroups using the clinical dysfunction index of Helkimo. No relation could be found between the number of occluding molars and premolars and the severity of the symptoms nor the evolution of the complaints. A weak correlation was found between the outcome of the treatment with the occlusal splint and occlusal adjustment, and the above mentioned occlusal parameters (r = 0.47).

Adolescent↗
PubMed1978

Functional occlusal forces: an investigation by telemetry.

In normal chewing the forces exerted on the occlusal surface seldom exceeded 10 to 15 pounds, as recorded by an eight-channel force transmitter in a removable fixed partial denture. Ninety-five percent of forces were less than 3.5 pounds for subject A, 2.0 pounds for subject B, and 10.0 pounds for subject C. The chewing frequency and the places of maximal force on the occlusal surface were relatively constant. The electromyographic chewing patterns could be considered normal in all circumstances. There was a remarkable statistically significant day-to-day variation in force values. The forces also changed for different kinds of food. The differences between maximum and minimum force values were highest in voluntary, nonfunctional movements.

Arachis↗
PubMedDate not supplied

Undergraduate and graduate education in prosthodontics in continental Europe.

Many factors, such as reduction in caries and periodontitis prevalence, decrease in the number of edentulous patients, and more frequent demand for implants, will have an important influence on prosthodontic treatment in the future. To provide more data on the reaction of prosthodontic departments to these changes and the implication in the teaching and training of dental students, a survey with 25 questions was sent to 40 universities in five European countries. The questions referred to teaching and training time in the three branches of prosthodontics; integration of periodontics, occlusion, and orthodontics; implant dentistry; and graduate training and postgraduate programs. The survey revealed that teaching and training in prosthodontics is still very conservative, not biologically oriented, and neglecting the future impact of changes in prevalence of caries and periodontal disease.

Education, Dental↗