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Biomedical subjects

S Terp

Publications and source records attributed to S Terp.

15 recordsLinked to original sources
PubMed1994

Force system developed from closed coil springs.

The present paper provides data on load-deflection rate and maximal force generated for 19 coil springs. The force level at activation and deactivation was registered at intervals of 5 mm between 0 and 100 per cent extension. Ten springs of each type were analysed. The following questions were answered. How many of the springs exhibited the behaviour of a superelastic spring and how many types of springs differed significantly from each other with respect to force deflection rate and maximal force level at 100 per cent extension? Of the products tested only the springs from GAC exhibited the behaviour characteristic of the superelastic wire. The 19 products could, from a clinical point of view, be classified into four different groups with regard to force deflection rate and five groups with regard to maximal force. The variation within each product also differed between the products with the lowest intra-product variation seen in the TP springs. In light of the present findings it is obvious that manufacturers' information was not satisfactory. The need for more thorough user information is stressed.

Elasticity↗
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

Screening for functional disorders of the masticatory system among teenagers.

This study evaluated the efficiency of a questionnaire as compared to a brief clinical examination for identification of clinically assessed craniomandibular disorder cases. 706 Danish children 14-16 yr old answered a self-administered questionnaire concerned with dysfunction symptoms and oral habits. In addition they were subjected to a clinical examination of signs of dysfunction from the masticatory system. Based on the present study a self-administered questionnaire for screening purposes used in an a priori healthy population of teenagers cannot be recommended. The answers to the questionnaire showed a low reproducibility and their ability to predict clinically assessed signs of dysfunction was inadequate. The most favorable combinations of single questions were calculated in order to optimize sensitivity, specificity, and predictive value of the questionnaire. A maximum of 65% of the clinically diseased subjects were identified by the questionnaire and only 41% of the test positive subjects had their subjective diagnoses confirmed at the clinical examination. The brief clinical screening procedure succeeded in identifying 92% of children with severely disturbed function. The subjects testing positively according to the brief clinical examination were children with either moderate or severe disturbances except for only one case. Based on a cost to benefit consideration a brief clinical examination is preferred to a self-administered questionnaire as a routine procedure for detection of craniomandibular disorders.

Adolescent↗
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↗
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↗
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↗
PubMed1987

Relationship between malocclusion and maintenance of teeth.

The relationship between the presence of malocclusion and maintenance of teeth in adulthood was studied in a randomly drawn sample of 499 35-44-yr-old Danes. Maintenance of teeth in the past was expressed through the number of teeth present, attachment level and information of regularity of dental visits. Maintenance at present was expressed as caries present, plaque and gingivitis. The relationship of these parameters to the presence of a malocclusion symptom was analyzed directly and the indirect influence was studied through the influence of a subjectively perceived malocclusion and its impact on satisfaction. It appeared that satisfaction was significantly related to maintenance of teeth and to a positive dental behavior. A perceived malocclusion was shown to have a negative influence on satisfaction and thus indirectly on maintenance. If a public orthodontic service is aiming at lifetime maintenance of teeth, malocclusions leading to dissatisfaction with teeth and a subjectively perceived need should be taken into consideration when ranking children with regard to treatment priority.

Adult↗
PubMed1982

The influence of extractions caries cause on the development of malocclusion and need for orthodontic treatment.

The influence of premature extraction of deciduous teeth, and extraction of permanent teeth due to caries on the frequency of malocclusions was analysed. The patient group comprised 915 children aged 8-16 from a province of Northern Italy. 204 children had experienced premature loss of deciduous teeth and 442 had had permanent teeth extracted, due to caries. The permanent teeth most frequently extracted were the first molars. It was obvious that extraction caries cause had detrimental effect on the development of occlusion resulting in an increased frequency of malocclusions. The frequency of single malocclusion traits was compared between the groups of children with and without loss of teeth. The malocclusion traits most frequently observed in children who had experienced extraction, were dentitional anomalies due to malaligned teeth. Only minor changes in the occlusal anomalies could be observed. There was, however, a pronounced increase in the need for minor as well as major orthodontic treatment. On the basis of these findings it could be concluded that extraction of teeth due to caries should be avoided if the aim of dental service on a population basis is to ensure a well functioning dentition for the maximum number of people.

Child↗
PubMedDate not supplied

Dental and skeletal maturity in adoptive children: assessments at arrival and after one year in the admitting country.

Seventy-one adoptive children from Asian countries, mainly Korea, were adopted by Danish parents. Height and weight were measured and dental and skeletal maturity assessed immediately after arrival and one year later. Increase in dental age was in complete concordance with the time interval between the two examinations. With regard to skeletal age, the majority of children showed an increased maturation rate although some of the youngest children seemed to be further retarded in maturation rate during their first year in Denmark. Comparison between two methods for assessing skeletal maturity revealed that the 'catch up' observed for children above one year of age was significantly more pronounced when assessed by the TW-2 method than when applying the G-P method. For the Korean children height and weight measurements increased more than the average values for the Danish population.

Adoption↗