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Biomedical subjects

B Melsen

Publications and source records attributed to B Melsen.

At least 91 records · Page 5Linked to original sources
PubMed1990

TMJ function and the effects on the masticatory system on 14-16-year-old Danish children in relation to orthodontic treatment.

The effect of orthodontic treatment on the functional status of the masticatory system was analysed in 706 children from three Danish communities. Three-hundred-and-eighty-eight (48 per cent) of the children were treated orthodontically and the 295 (37 per cent) of the total population had terminated the treatment and were included in the analysis. Fifty-seven cases (7.1%) of the total population were discontinued before the orthodontic treatment was considered finished by the orthodontist. Discontinuation did not, however, seem to influence the functional status. Increasing the orthodontic treatment frequency from 38 to 51 per cent did not decrease the functional problems of a young population. On the contrary, the community with the lowest treatment frequency (38 per cent) demonstrated fewer functional problems among the orthodontically treated subjects than did the two communities with higher treatment frequencies, indicating paradoxically that it may be a functional risk to treat the last 13 per cent with minor discrepancies. Tenderness on palpation of the musculature and the TMJ capsule were generally more prevalent among orthodontically treated subjects. Children who had their treatments performed by either orthodontist or paedodontist alone demonstrated more muscular problems than children who had been treated by a team of orthodontists and paedodontists. Related to the severity of the malocclusion these findings stress the importance of more consideration to establish a functionally satisfactory occlusion after orthodontic treatment. Functional status was not related to the type of orthodontic treatment, including extraction therapy, use of either fixed or removable appliances.

Adolescent↗
PubMed1990

Buccal mucosa fibroblasts and periodontal ligament cells perturbed by tensile stimuli in vitro.

Human buccal mucosa fibroblasts and periodontal ligament cells grown in tissue culture were subjected to tensile forces approximating those used for orthodontic bodily tooth movement. The cells were synchronized into pre S phase and positively tested for response to nonmechanical physical stimuli. Two-dimensional gel analysis and immunohistochemical analysis of the three cytoskeletal components showed a lack of response. Similar negative results were found when the cells were perturbed in the presence of substance P. We hypothesize that perhaps these cells respond more readily to injury, a secondary effect of the forces of tooth movement, than to tensile forces.

Cell Membrane↗
PubMed1990

Postsurgical change of mandibular position in patients following Le Fort I osteotomy.

Mandibular displacement during and following maxillary osteotomy was observed. Cephalometric data obtained from radiographs produced before, immediately after, and at a minimum of 6 months after were analyzed. The displacement of the maxilla and of the mandible during and after surgery was studied, and the predictive value of maxillary displacement on the changes occurring in the mandibular region was evaluated by a stepwise regression analysis. The results indicated that as the maxilla was displaced superiorly, the mandible also displaced anterosuperiorly without significant relapse. The rotation and the vertical displacement of the maxilla during the Le Fort I osteotomy accounted for two thirds of the total mandibular change. Vertical displacement of the maxilla and mandible were significantly correlated, indicating that mandibular displacement and rotation can be predicted from maxillary displacement.

Adult↗
PubMed1990

Calvarial sutural abnormalities: metopic synostosis and coronal deformation--an anatomic, three-dimensional radiographic, and pathologic study.

The purposes of this study were (1) to evaluate the histologic differences between synostotic versus deformational suture abnormalities and (2) to correlate these histologic findings with anatomic and three-dimensional computed tomographic (CT) scans. We examined three infants with premature metopic synostosis; one infant also had microcephaly trisomy 13 and curious overriding of the coronal sutures. The three-dimensional CT scans demonstrated obliteration of the metopic suture inferiorly. Histologic sections of this suture showed complete bony stenosis. The same pattern was found in all three infants, including the two infants with trigonocephaly who did not have trisomy 13 or microcephaly. In the trisomy 13 infant, the overlapped inferior coronal suture was obliterated on CT examination. However, histologic sections in this region showed a merging of bone; there was no synostosis. In summary, three-dimensional CT re-formation correlated with metopic suture histology. "Stenotic" fusion existed in all infants with trigonocephaly, those with normal and abnormal karyotypes, with and without microcephaly. However, three-dimensional CT re-formation of the trisomic infant showed opacification of the coronal suture in the areas of greatest overlap, whereas histology revealed a curious bone remodeling pattern, possibly a precursor to "deformational" craniosynostosis.

Abnormalities, Multiple↗
PubMed1989

Force system developed by V bends in an elastic orthodontic wire.

The force system generated by a simple V bend in a straight wire was studied by means of the principles for small deflection of a beam and a model developed for the description of the forces and moments. The relationship between the size of the bend and the interbracket position on the force system developed is analyzed and discussed in relation to clinical problems. The parallel between positioning of a V bend and the "geometries" developed between a straight wire and angulated brackets is drawn. Four principally different force systems could be developed by the V bend and a method for the predetermination of the force systems is provided. The general principles are exemplified for wires with different moduli of elasticity, varying materials, and cross-sectional dimensions. Stainless steel and beta titanium (TMA) wires in dimensions of 0.16 inch and 0.017 x 0.025 inch are given as examples.

Dental Stress Analysis↗
PubMed1989

Intrusion of incisors in adult patients with marginal bone loss.

Elongated and spaced incisors are common problems in patients suffering from severe periodontal disease. Thirty patients characterized by marginal bone loss and deep overbite were treated by intrusion of incisors. Three different methods for intrusion were applied: (1) J hooks and extraoral high-pull headgear, (2) utility arches, (3) intrusion bent into a loop in a 0.17 x 0.25-inch wire, and (4) base arch as described by Burstone. The intrusion was evaluated from the displacement of the apex, incision, and the center of resistance of the most prominent or elongated central incisor. Change in the marginal bone level and the amount of root resorption were evaluated on standardized intraoral radiographs. The pockets were assessed by standardized probing and the clinical crown length was measured on study casts. The results showed that the true intrusion of the center of resistance varied from 0 to 3.5 mm and was most pronounced when intrusion was performed with a base arch. The clinical crown length was generally reduced by 0.5 to 1.0 mm. The marginal bone level approached the cementoenamel junction in all but six cases. All cases demonstrated root resorption varying from 1 to 3 mm. The total amount of alveolar support--that is, the calculated area of the alveolar wall--was unaltered or increased in 19 of the 30 cases. The dependency of the results on the oral hygiene, the force distribution, and the perioral function was evaluated in relation to the individual cases. It was obvious that intrusion was best performed when (1) forces were low (5 to 15 gm per tooth) with the line of action of the force passing through or close to the center of resistance, (2) the gingiva status was healthy, and (3) no interference with perioral function was present.

Adult↗
PubMed1989

Prevalence, interrelation, and severity of signs of dysfunction from masticatory system in 14-16-year-old Danish children.

A clinical evaluation of the functional status of the masticatory system was performed on 706 14-16-yr-old children who had received a minimum of 9 yr regular dental care and had only natural teeth. Applying a classification system developed for this specific age group, 19% were assigned to the group with moderate and 11% to the group with severe disturbances. An analysis of the association between the signs of dysfunction revealed that TMJ clicking was always associated with some but not necessarily numerous palpatory findings. The localizations of the TMJ clickings were related to specific signs of dysfunction from the masticatory system. Restriction of movement capacity of 2 standard deviations was frequently found as an isolated phenomenon, whereas restriction of 3 standard deviations was always associated with either palpatory findings or sounds from the joints.

Adolescent↗
PubMed1989

Occlusal tooth contacts in natural normal adult dentition in centric occlusion studied by photocclusion technique.

The inter- and intraexaminer reproducibility in the interpretation of the registrations of the photocclusion technique as well as the number of occlusal contacts and their intensity in natural normal dentition in centric occlusion were studied in 20 adults. No significant differences were found regarding the inter- and intraexaminer interpretations for both number and intensity of occlusal contacts. A mean number of 23.8 contacts per individual, an almost symmetric and balanced distribution of the contacts between left and right sides of the dentition, and an absence of any significant differences between female and male subjects characterized the normal natural dentition.

Adult↗
PubMed1989

The morphology of the nasal septum in identical twins.

A comparison was made of the nasal septums of 41 pairs of identical twins to assess the impact of genetic and environmental factors on the formation of deformities of the nasal septum. Deformities of the anterior nasal septum (cartilaginous septum) were present in 22% of all the individuals studied, and in the posterior nasal septum (bony septum), some deformity was present in 74% of the persons studied. The distribution of deformities within pairs suggests that anterior deformities might be of external origin (e.g., traumatic), and posterior deformities may be considered to be part of a normal developmental process of the maxillary complex, where both genetic and epigenetic factors may play a role.

Adolescent↗
PubMed1989

Concerns, motivation, and experience of orthognathic surgery patients: a retrospective study of 152 patients.

Patient perceptions and motivations for undergoing orthognathic surgery were evaluated retrospectively by a 15-item self-administered questionnaire. Surgical risk was the major reservation concerning having an operation, and change in appearance and cost of treatment were of next greatest concern. Of the 152 patients, 78.3% would elect to have surgery again. Female patients desired improvement in appearance more than male patients.

Adolescent↗
PubMed1989

[Periodontal response to orthodontic treatment].

Monkeys bicuspids were subjected to experimental periodontitis inducing pockets with bifurcation involvement. Light continuous extrusive and intrusive forces were then applied on these bicuspids. The extrusive forces were applied on 3 monkeys; bone apposition was obtained. The intrusive forces were applied on 4 monkeys after pocket surgery and careful root surface scaling. A meticulous hygiene program was then maintained. In these conditions new attachment was gained through intrusion.

Animals↗
PubMed1989

Stomatognathic function of patients who seek orthognathic surgery to correct dentofacial deformities.

To determine the craniomandibular functional status of patients who seek orthognathic surgery, 48 adults with various dentofacial deformities were examined, and the functional parameters of the patients were compared with those of a normal population. The relationship between function and morphology was also studied. The method of study included a clinical examination of dysfunction, an evaluation of the number and intensity of occlusal contacts, a kinesiographic analysis of mandibular movements at the incisors, an evaluation of ramal and condylar vertical symmetry by means of dental rotational panoramic radiography, and an examination of profile and frontal cephalograms. Results of the examinations showed that the patients seeking orthognathic surgery showed craniomandibular functional patterns different from those of the normal group or healthy population. However, because no significant correlations were found among specific morphologic and functional characteristics and dysfunctional status (with the exception of condylar asymmetry, the maximal deviation of a maximal opening-closing movement defined on the sagittal plane, and the inclination of the maxillary central incisor in relation to the anterior cranial base), no clear cause-effect relationship was proved.

Cephalometry↗
PubMed1988

New attachment through periodontal treatment and orthodontic intrusion.

The present study was performed to investigate the tissue reaction related to orthodontic intrusion of teeth with a reduced periodontium and further to evaluate the influence of oral hygiene on this reaction. In each of five Macaca fascicularis monkeys, periodontal tissue breakdown was induced around the premolars and the upper incisors by placing orthodontic elastic ligatures around the teeth. The breakdown procedure was continued until a minimum of four pockets could be measured on probing. Following removal of the elastics, a flap operation was performed. The pocket epithelium and granulation tissue were excised. During the surgical procedure, a notch was placed just above the bone. The teeth were divided postoperatively into four groups according to treatment: group 1 = flap operation, no oral hygiene program; group 2 = flap operation plus oral hygiene program three times per week; group 3 = flap operation plus intrusion, no oral hygiene program; and group 4 = flap operation plus intrusion plus oral hygiene. Groups 3 and 4 were subdivided into two observation periods. A total of 60 teeth corresponding to 120 approximate surfaces were studied. The animals were killed with perfusion; histologic sections were produced and stained alternatively with hematoxylin and eosin, and van Gieson's solution. The histologic analysis showed that new cementum formation and new collagen attachment were observed following the surgical procedure if the oral hygiene was maintained, but also demonstrated that the intrusion improved the quantity of new attachment if carried out under healthy conditions. New attachment was a consistent finding in group 4, but varied from 0.7 to 2.3 mm. In case of intrusion without oral hygiene, the results varied from moderate new attachment to an aggravation of the periodontal bone loss. On the basis of the results presented here, the combination of periodontal treatment and orthodontic intrusion seems to be a method by which improvement of the periodontal condition can be obtained, provided that both the biomechanical force system and the oral hygiene are kept under control.

Animals↗
PubMed1988

Clinical classification of 14-16-year-old Danish children according to functional status of the masticatory system.

The high prevalence of functional disturbances in the masticatory system and the tendency to increasing severity with duration stresses the necessity for a reproducible index. Clinical examination of the masticatory system was performed in 14-16-yr-old children. The sequence of examination, TMJ-muscles-opening capacity was chosen in order to minimize the bias. For the same reason, information on symptoms and occlusal conditions was not available for the examiner. According to the amount and character of the signs of dysfunction, the children were classified into three groups. Both single traits of dysfunction and the classification of the subjects were tested for reproducibility. The reproducibility of the compound clinical index was high. The ability to differentiate between children with moderate/severe signs and without signs was higher but the highest value was reached when differentiation was made between children with no/moderate signs and children with severe signs.

Adolescent↗