Biomedical subjects

B Thilander

Publications and source records attributed to B Thilander.

At least 37 records · Page 2Linked to original sources

PubMed1994

Osseointegrated implants in adolescents. An alternative in replacing missing teeth?

In 15 adolescents (13 years 2 months-19 years 4 months) in the late dental stage, Brånemark implants (n = 27) were chosen to replace missing teeth due to congenital absence or trauma. The patients were followed for at least 3 years, at yearly intervals, biometrically and radiographically. No fixture losses occurred. Only minor loss of bone support at the fixtures was observed, while adjacent tooth surfaces showed some loss in some cases. Infra-occlusion of the implant restorations was noticed in patients with residual craniofacial growth. Thus, the dental and skeletal maturation, and not the chronological age of the patient, must be taken into consideration to avoid infra-occlusion of the fixture crown. Furthermore, it is important to gain enough space for the fixture in the mesio-distal direction, to avoid the risk of marginal bone loss at teeth that are adjacent to it.

Adolescent↗

PubMed1994

Osseointegrated implants as orthodontic anchorage in the treatment of partially edentulous adult patients.

In nine partially edentulous adult patients, mean age 47 years (range 17-64 years) 23 osseointegrated implants were used as orthodontic anchorage to perform the following types of orthodontic tooth movements: tipping, torquing, rotation, intrusion, extrusion, and those associated with bodily movements. The total orthodontic treatment period varied between 4 and 33 months (x = 17 months). Pre-operatively, at the start and end of orthodontic treatment, and at the annual controls, clinical as well as biometric and radiographic (panoramic, lateral cephalograms and periapical radiographs) recordings were performed. The osseointegrated anchorage units were used as reference points for measurements of two- and three-dimensional tooth movements with a co-ordinate machine. The 2-D tooth movements varied between 0.2 and 6.2 mm, whereas movements in the third dimension, extrusion and intrusion, ranged from 0.0 to 13.5 mm. The movement in space for the individual tooth was observed to be, as a mean, 3.9 mm (range 0.6-18.7 mm). However, the osseointegrated titanium implants (fixtures) used as orthodontic anchorage remained in position when orthodontically loaded for the various tooth movements. After completion of the orthodontic treatment the fixtures served as abutments for permanent prosthetic constructions.

Adolescent↗

PubMed1994

Condylar height on panoramic radiographs. A methodologic study with a clinical application.

The aim of this study was to develop and apply a reliable method of measuring the effects of condylar lesions quantitatively on panoramic radiographs. Three different types of machines were tested. Two dry skulls were exposed in six positions in each machine, and the relative size of the condyle in relation to ramus height was calculated. The results showed good validity for the reference points used. The head position did not contribute to the variation in the measurements, but the type of panoramic machine had some influence. It was concluded that the method may be applied when calculating condylar ratios, provided that the same panoramic machine is used. The relative height of the condyle in relation to ramus height was measured bilaterally in three groups of children, with either normal or postnormal occlusion or with juvenile chronic arthritis (JCA), to detect possible asymmetries and define differences in the relative condylar height. The JCA group had a significantly shorter relative condylar height, and asymmetries were commoner than in the other two groups.

Adolescent↗

PubMed1993

Periodontal tissue response to orthodontic movement of teeth with infrabony pockets.

The aim of this study was to evaluate the effect of orthodontic tooth movement on the level of the connective tissue attachment in sites with infrabony pockets. The experiment was carried out in four beagle dogs. The second and fourth premolars were extracted. After healing, angular bony defects were prepared at the mesial aspect of the third premolars. The exposed root surface was scaled and planed, and a notch was prepared at the bottom of the defect. Plaque-collecting cotton floss ligatures were placed around the neck of the teeth and maintained in situ for 3 weeks, followed by an additional 2 months of plaque accumulation before the orthodontic tooth movement was initiated. In each dog, one premolar was moved away from the angular bony defect and one premolar into and through the angular bony defect. The maxillary third premolars served as control teeth and were not subjected to orthodontic tooth movement. After orthodontic treatment (5 to 6 months), the teeth were stabilized for a period of 2 months before biopsy sampling. Clinical, radiographic, and histologic evaluations revealed that it was possible to establish and maintain an infrabony pocket with a subcrestal, plaque-induced inflammatory lesion during the entire course of the study. While the control teeth had maintained their attachment levels, all but one of the orthodontically moved teeth showed additional loss of attachment.(ABSTRACT TRUNCATED AT 250 WORDS)

Alveolar Process↗

PubMed1993

Tissue reactions towards titanium implants inserted in growing jaws. A histological study in the pig.

In this investigation, the tissue reactions towards titanium implants inserted in growing jaws of pigs were studied by means of histology. At the age of 12 weeks, 5 test pigs each received 4 Brånemark System titanium implants (fixtures). The fixtures were inserted immediately after extraction of the mesial root of the second deciduous premolar (P2) and the deciduous canine (C) on one side of the mandible and the mesial root of the first deciduous premolar (P1) on the other side. The fourth implant was placed after extraction of the deciduous lateral incisor (L) on one side in the upper jaw. Furthermore, 1 pig in which no extractions or fixture installations were performed served as a control. All pigs were followed for 165 days with clinical, radiographic and biometric examinations, the results of which have been previously presented. In this study, 10-microns-thick ground sections were produced for histology after the jaws had been fixed by immersion in formalin and further processed and embedded in plastic resin. Six of the fixtures originally inserted were lost during the experimental period, and the remaining implants were found to be involved with mineralized bone to varying degrees. Regarding the fixture-to-teeth relationship, it was found that, in the premolar region of the lower jaw, the teeth were positioned superior to and buccally angulated in relation to the fixtures. In the upper jaw, the implants were positioned below the adjacent teeth but centrally in the alveolar process. Tooth germs adjacent to the fixture had a displaced eruption path, buccally or lingually to the fixture. If the bud developed in close contact with the fixture, a changed morphology of the germ could be observed.

Alveolar Process↗

PubMed1993

Orthodontic tooth movement into edentulous areas with reduced bone height. An experimental study in the dog.

The present study was performed in order to test the hypothesis that the height of supporting bone and connective tissue attachment will be maintained around teeth bodily moved into areas of reduced bone height. During a pre-experimental period, areas with markedly reduced bone height were produced in the mandible of 4 beagle dogs through extraction of the 4th premolars and subsequent surgical reduction of the bone height in the extracted sites to a level corresponding to half the root length of the 3rd premolar. Following healing, one of the third premolars was bodily moved in a distal direction into the area of reduced bone height, while the contralateral premolar served as a non-moved control. After 6 months of active tooth movement, the teeth were retained in their new position for a further 2 months before biopsies of test and control tooth sites were sampled. Radiographic evaluation showed that a bodily movement had been achieved with no or only minimal vertical displacement of the teeth. The histological analysis revealed that none of the teeth, orthodontically moved or not, had experienced loss of connective tissue attachment. Although a greater distance between the cemento-enamel junction and the bone crest was found on the pressure side of the orthodontically moved test teeth in comparison to the contralateral, non-moved control teeth, the bone level at all test teeth was more coronally positioned than the original, reduced bone level in the area into which the test teeth had been moved. Hence, these findings indicate that a tooth with a normal height of periodontal support can be orthodontically moved into an area of markedly reduced bone height with maintained height of the supporting apparatus.

Alveolar Bone Loss↗

PubMed1992

Craniomandibular disorders with special reference to orthodontic treatment: an evaluation from childhood to adulthood.

The purpose of the present study was to reexamine a group of children and adolescents with respect to signs and symptoms of craniomandibular disorders (CMD) and to evaluate whether any differences could be found between persons who had received orthodontic treatment earlier and those who had not. A total of 402 children in three age groups (7, 11, and 15 years) had participated in a cross-sectional study on the relationship between malocclusion and signs and symptoms of CMD. Ten years later they were asked to answer a questionnaire. In the youngest age groups (now 17 and 21 years old) 190 (76%) subjects answered the questionnaire. In the oldest age group (now 25 years old) completed questionnaires were received from 103 (84%) subjects, and 83 (62%) of those subjects appeared for a clinical examination. Subjects with a history of orthodontic treatment had a lower prevalence of subjective symptoms of CMD (TMJ sounds included) than those without any experience of orthodontics. Although the differences were small, it was more evident for the oldest age group. The clinical examination has shown that persons who had undergone orthodontic treatment had a significantly lower clinical dysfunction index than those who had not.

Adolescent↗

PubMed1992

Aspects on osseointegrated implants inserted in growing jaws. A biometric and radiographic study in the young pig.

The aim was to study if osseointegrated implants behave like teeth in the growing jaw. Six young pigs were used, one of them randomly selected as a control. The test pigs received four fixtures each in regions with various dento-alveolar development. The biometric and radiographic findings, after an experimental period of 165 days, showed that the osseointegrated implants do not become secondarily displaced in sagittal and transversal dimensions and, thus, do not behave like normal teeth. Consequently, the osseointegration technique is not to be recommended in the lateral regions in young children.

Alveolar Process↗

PubMed1991

The effect of osseointegrated implants on the dento-alveolar development. A clinical and radiographic study in growing pigs.

In an attempt to study the effect of osseointegrated implants on vertical dentoalveolar development, six growing pigs of the Pigham strain were used, one of them randomly selected as a control. The test pigs received four fixtures each, three in the lower jaw and one in the upper. The fixtures were placed in areas where different patterns of the dento-alveolar development were expected. The clinical and radiographic findings have clearly shown that the implants do not behave like normal erupting teeth during the development of the dentition. Neither do the fixtures move together with the adjacent teeth, but behave more like ankylosed teeth.

Alveolar Process↗

PubMed1991

Examination of Chinese NiTi wire by a combined clinical and laboratory approach.

Chinese NiTi wire was compared with Nitinol and stainless steel wires in a combined laboratory and clinical examination. In the laboratory test, the loading and unloading-deflection properties of the wires were determined in a three-point bending test and their surface properties were studied in a scanning electron microscope. This test attempts to simulate a common clinical situation. The NiTi material showed a non-linear force-deflection relationship. The increase in force from 1 mm deflection and onwards was very slow and the force delivered during unloading from large deflections was almost constant. This behaviour was somewhat different for smaller downward deflections of NiTi wires. Plastic deformation was insignificant. The clinical study confirmed the laboratory results obtained, characterizing a wire material much superior to stainless steel and even superior to Nitinol for alignment purposes. In clinical use, however, the rate of fractures of NiTi wires turned out to be unsatisfactorily high. This disadvantage was not predicted by the three-point bending test. Scanning electron microscopy revealed surface defects and non-metallic inclusions in fractured NiTi wires. A combination of a bending test simulating a clinical situation and surface examination is recommended when new wire materials are to be tested.

Alloys↗

PubMed1991

Periodontal tissue reactions to orthodontic extrusion. An experimental study in the dog.

Orthodontic tooth extrusion is used at crown lengthening procedures or in conjunction with periodontal therapy aimed at eliminating or reducing angular bone defects. A technique for orthodontic extrusion combined with resection of the supracrestal attachment fibers (fiberotomy) was recently proposed as an adjunct to certain restorative procedures. The aim of the present investigation was to analyze reactions of the periodontal tissues to orthodontic extrusion when combined with fiberotomy. In 5 beagle dogs, the mesial roots of the 2nd, 3rd and 4th hemisected mandibular premolar were used as target roots while the distal roots served as reference units. After a baseline examination, an orthodontic extrusion device (stent) was installed and reactivated at 2-week intervals during an 8-week period of active tooth movement. Immediately following the installation of the stent and once every 2nd week, the target roots were exposed to fiberotomy. After the active period, the teeth were retained in their new position for a period of 8 weeks. Clinical, radiographical and histological measurements were performed. The results from the investigation demonstrated that orthodontic extrusion combined with supracrestal fiberotomy resulted in a coronal displacement of the tooth and was associated with pronounced recession of the gingival margin and extensive loss of connective tissue attachment. The degree of gingival recession and the amount of loss of connective tissue attachment were, however, less extensive than the amount of tooth extrusion. Thus, repeated fiberotomy obviously failed to entirely prevent coronal migration of the attachment apparatus. It was also observed that undesired attachment loss had occurred at the reference roots.

Animals↗

PubMed1991

Dentofacial relations in young adults with unilateral complete cleft lip and palate. A follow-up study.

A retrospective study was made on 30 patients born between 1958 and 1969 with unilateral complete cleft lip and palate (C-UCLP) and operated on at the Department of Plastic Surgery, University Hospital, Umeå, Sweden. All patients were operated on by the same surgeon. The results are based on data from records at 5, 10, 16 and 20 years of age. The facial morphology of the cleft children at 5 years of age was rather close to that of the normal children. During growth the faces became retrognathic, more visibly so in the maxilla resulting in straight or concave profiles. This was more evident among the boys. There were no differences regarding maxillary growth between children bone grafted at 10 to 16 years of age and those bone grafted after 16 years of age or not at all. Although surgical procedures and orthodontic treatment varied, 70% had less than 3 teeth in crossbite relationships at 20 years of age. An important factor to take into consideration is the fact that in addition to the influence that the cleft morphology and treatment have on the dentofacial growth, other dentofacial growth patterns also exist among the cleft patients. Generally the groups of patients reported are rather small and therefore conditions like these can have a strong influence on the results.

Adolescent↗

PubMed1991

Orthodontic aspects on a skull collection from the Carmelite monastery in New Varberg.

During an excavation of the Carmelite monastery in New Varberg, 178 skeletons were found. Many of the skulls were in a bad condition. Thus, the material in the present study consists of 12 complete and 47 partial skulls (maxilla and/or mandible) of 22 monks and 37 ordinary inhabitants. The information collected involved direct inspection of the skulls, segments of the jaws and radiographic examination of the complete skulls. Malocclusion, attrition, temporomandibular joints and arch dimensions were analysed. From the results it is tempting to assume that lack of forceful masticatory function and consequent absence of evenly distributed attrition and observed differences in craniofacial morphology can be a major explanation to the high prevalence of severe malocclusion in modern man.

History, 15th Century↗

PubMed1990

Transalveolar transplantation of maxillary canines. A follow-up study.

This follow-up study on transalveolar transplantation includes 56 maxillary impacted canines in 47 patients, with a post-operative control period of 2-10 years (mean 4.7 years). The prognosis of the transplanted teeth is still very good; only two canines have been lost, due to poor oral hygiene or fracture of the tooth. These positive follow-up results indicate that transalveolar transplantation will offer greater flexibility in the treatment of impacted maxillary canines in adults.

Adolescent↗

PubMed1990

A longitudinal study on malocclusion in relation to signs and symptoms of cranio-mandibular disorders in children and adolescents.

Two-hundred-and-thirty-eight subjects in three different age-groups (7, 11, and 15 years) were followed over a period of 4-5 years in respect of morphological malocclusions, and signs and symptoms of functional disturbances. About half of the 7-year-olds had at least one of the morphological malocclusions registered while the corresponding figure was 38 per cent at the age of 20. Some subjects had received corrective orthodontic treatment. When compared with subjects without such treatment, there were no differences in prevalences of occlusal interferences, nor in signs or symptoms of craniomandibular disorders (CMD). The associations between CMD and different morphological malocclusions were low. Nevertheless, some malocclusions were found to be more important than others. In a long-term perspective cross-bite, both uni- and bilateral, anterior open bite, post-, and prenormal occlusion had some association with the development of CMD.

Adolescent↗

PubMed1990

Anterior open bite treatment with magnets.

The aim of this study was to examine the effects of repelling magnets on the treatment of anterior open bite and compare them with the effects of acrylic posterior bite-blocks. Twenty patients, aged 9-16 years with skeletal anterior open bite, were randomly divided into two groups. In one group the patients wore posterior repelling magnet splints and in the other they wore acrylic posterior bite-blocks of the same thickness as the magnet splints. The patients were instructed to use their appliance as much as possible (the minimum accepted being 18 hours daily) during a 6-month period. Dental casts, intra-oral photos, and lateral cephalograms were taken before and after treatment, and the patients were also examined regularly to identify the development of any craniomandibular disorders. In the first group, the dental and skeletal vertical relation responded quickly to the magnet treatment. The open bite was generally closed in just under 4 months, especially in patients in early mixed dentition. Spacing in the labial segments decreased in some cases, while slight crowding was induced in others. Transverse problems, i.e. unilateral cross-bite, sometimes followed by scissor-bite on the opposite side, was observed in those patients who were in the early mixed dentition and had used the magnets intensively. The patients who wore acrylic posterior bite-blocks also showed improvement in the dental and skeletal vertical relationships, especially during the first months. This was followed by a 'plateau' period. No transverse problems were found in these patients.

Acrylic Resins↗

PubMed1989

The craniofacial morphology in persons with maxillonasal dysplasia (Binder syndrome). A longitudinal cephalometric study of orthodontically treated children.

The aim of this investigation was to study the influence of orthodontic treatment on facial growth in subjects with maxillonasal dysplasia. The subjects were followed longitudinally from early childhood until growth was completed or almost completed. Fifteen patients, 9 boys and 6 girls, were orthodontically treated by conventional methods. They were compared with (1) another longitudinal group consisting of 13 orthodontically untreated children, 7 boys and 6 girls with the same syndrome, and (2) with a control material taken from computer-filed data on Swedish children and young adults with orthognatic profiles and normal occlusion. The orthodontic treatment led to acceptable dental conditions in 10 of the patients. No influence on craniofacial growth could be demonstrated. However, the mean facial polygons of the children showed that certain differences already existed at early ages between the treated subjects with a generally more severe form of the syndrome and the untreated children. The growth pattern seemed, however, to follow about the same rate in both groups. In six patients the orthodontic treatment was followed by surgical correction at adult age to solve their craniofacial problems. The optimum care of these patients requires an interdisciplinary treatment approach with thorough treatment planning by orthodontists in collaboration with oral and plastic surgeons.

Cephalometry↗

PubMed1989

The effect of thyroxine on craniofacial morphology in the growing rat. Part I: A longitudinal cephalometric analysis.

The wide therapeutic use of hormones enhances the importance of detailed knowledge of the effects on skull growth. Thyroxine is known to regulate maturation of cell populations and long bone growth, but the influence on craniofacial bone remodelling is still obscure. One side effect of substitution therapy with thyroxine in children is premature closure of cranial sutures. The aim of the present study was to describe longitudinally the effect of different serum levels of thyroxine on craniofacial growth. In young rats injected with 20 micrograms/kg b.w. l-thyroxine for 28 days a change was found in craniofacial morphology measured by a cephalometric technique. A decrease in length of the viscerocranium was evident after 14 days, and occurred in connection with raised serum levels of thyroxine. In contrast, cranial base growth was increased between day 14 and 28 and also a catch-up growth in the viscerocranium was observed during this period. This observed change occurred after the induced peak in levels of thyroxine in serum had subsided. The inhibited forward directed growth of the viscerocranium was consistent with the fact that the skull in the thyroxine group developed a klinorhycial form in contrast to the normal orthocranialization. Thus, the craniofacial growth pattern was influenced by variations in the serum level of thyroxine. The effects of thyroxine on skull growth sites observed are consistent with reported effects of low dose of thyroxine on long bone growth.

Animals↗