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- Gordh, Monica
(författare)
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Survival of onlay bone grafts. A study in the adult rat.
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this thesis was to study onlay bone grafting in the adult rat to improve graft incorporation and perservation of graft size. In 167 adult isogeneic lewis rats, the size maintenance and bone formation at the graft-host interface of uni- and bicortical onlays positioned in various environments and treatments were investigated. The findings were assessed after four, 12 and 20 weeks with routine histology and immunohistochemistry, using antibodies against some bone and cartilage matrix proteins and proteoglycans. The immunolabelling aimed to explore the possible occurence and localization of such proteins which are essential to various stages of osteogenesis and bone repair. The main findings were: Bicortical grafts were found to retain volume better than unicortical grafts and the exposed bone-marrow space of the graft was sealed off from the surrounding connective tissue by compact bone, emanating from the cortical margins of the graft. A major improvement in graft incorporation was observed following exposure of the underlying recipient marrow. On the other hand, these grafts were occasionally markedly submerged into the recipient bed, which was believed to be due to the disappearance of its pressure-resistant outer cortical layer. The effects of limited marrow exposure by cortical perforations of the recipient bed resulted in a migration of the recipient bone marrow into the graft as well as decreased graft size diminution. A combination of cortical perforations of a bicortical graft and the host bed entailed increased graft stability and corticalization of the marrow. When the graft was covered by an osteopromotive expanded polytetrafluoroethylene (e-PTFE) membrane, improved graft integration and greater size persistence was observed even after membrane removal. However, full volumetric maintenance of the graft was not accomplished in any of these studies. The combined treatment of the higher concentration (32µg/80µl) tested recombinant human bone morphogenetic protein-2 (rhBMP-2) and membrane lead to a rapid and complete graft integration and pronounced bone formation resulting in maintained or even enhanced graft size. In contrast, the application of high-dose rhBMP-2 without a membrane resulted in loss of graft size, extensive bone resorption and only small amounts of new bone formation. Therefore, when a collagen carrier is used for rhBMP-2 in conjunction with onlay bone grafting, our results indicate the advantage of applying a membrane to obtain graft volume persistence. The immunohistochemical labelling contributed to a more detailed picture of the mechanisms involved in graft incorporation and offered a dynamic indication of the bone repair and remodelling process as compared to routine histology.
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- Vallon, Danila
(författare)
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Studies of occlusal adjustment therapy in patients with craniomandibular disorders
- 1997
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the first part of this thesis, measurement and registration procedures of occlusal interferences and their inter and intraobserver variability were evaluated. In the second part of this thesis, the short and long-term effect of occlusal adjustment therapy was prospectively assessed in a controlled clinical trial in a selected group of 50 patients with myogeneous craniomandibular disorders (CMD). The treatment outcome of occlusal adjustment and combined treatment modes was investigated up to 7 years. The selcted patients were compared with a group of consecutive CMD patients. Observer variability was the same for the different methods of registration and was acceptable for most of the occlusal variables investigated. As the intraobserver constancy was greater than that between observers repeated registrations in longitudinal studies should be done by the same observer. Occlusal adjustment had in a short-term perspective of 1 to 3 months a positive effect on symptoms and clinical signs of CMD but had little or no effect in the long-term perspective in this group of muscular CMD patients. The usefulness of occlusal adjustment as the only form of treatment for this subgroup of CMD has limitations as the majority of patients had demanded several treatment modes in a 7-year perspective. The long-term effect of a combined treatment approach was good. The strongest associations in relation to treatment outcome were found for the variables stress and demand of treatment. The selected group was comparable to a consecutive CMD group with respect to background factors of socioeconomical character and the result from this selected group can therefore be applied to a broader group of CMD patients.
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- Flygare, Lennart, 1961-
(författare)
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Degenerative changes of the human temporomandibular joint : A radiological, microscopical, histomorphometrical and biochemical study
- 1997
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In five autopsy specimen studies human temporomandibular joints were investigated by conventional tomography, macroscopy, and microscopy for degenerative changes, in particular erosive hard-tissue changes.In the microscopical evaluation special attention was paid to the calcified cartilage. The calcified cartilage was outlined by a flat or gently undulating basophilic tidemark and an irregular osteochondral junction. A significant correlation was found between the thickness of the calcified cartilage and that of the total articular cartilage. Two types of erosive changes were found; an extensive type with complete loss of overlying cartilage and a local type with retained cartilage. The erosive changes were generally more extensive in the condyle. Microscopically, the erosive changes in the condyle were evenly distributed. In the temporal component there was a slight predominance of these changes located to the lateral part of the tubercle. Tomography underestimated both the presence and the extent of the erosive changes. Positive predictive values and negative predictive values were 0.70 and 0.83, respectively, for changes in the condyle and 0.91 and 0.68 for changes in the temporal component. The likelihood ratio for a positive test was 10.6 in the temporal component and 5.6 in the condyle. The likelihood ratio for a negative test was comparable in the two joint components 0.49 and 0.47 respectively. Three different techniques of computer-aided bone histomorphometry (manual, automatic and semi-automatic) were assessed. The variation when assessing the total and trabecular bone volume was evaluated. Good reproducibility in the assessment of the total and trabecular bone volume was achieved with the aid of a single observer and a semi-automatic technique. This technique was therefore used to assess the total and trabecular bone volume in condyles and temporal components of joints with and without microscopically verified erosive changes. Condyles with erosive changes demonstrated both a higher trabecular bone volume (P< 0.05) and higher total bone volume (P< 0.01) than condyles without erosive changes. In a clinical study on patients undergoing diskectomy, the two cartilage matrix macromolecules aggrecan and cartilage oligomeric matrix protein (COMP) were quantified by enzyme-linked immunosorbent assay in lavage fluids from temporomandibular joints before and six months after surgery. The aggrecan/COMP ratio was higher in the lavage fluid of all joints at follow-up as compared to preoperatively. All joints developed radiographic changes indicative of degenerative changes (osteoarthrosis) during the postoperative period.
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| 5. |
- Knutsson, Kerstin
(författare)
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The mandibular third molar. Dentists' judgement in the removal of asymptomatic molars
- 1996
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim was to study dentists' judgement on the removal of and on the development of pathology associated with asymptomatic mandibular third molars. Thirty general dental practitioners (GDPs) and 10 oral surgeons were asked to judge 36 molars with equal distribution of three cues: patient's age, angular position and degree of impaction of the molar. Rating on a VAS was found to be an appropriate method to analyse the need for removal of asymptomatic molars. The number of molars proposed for removal varied between O and 26 for the GDPs and between 3 and 21 for the oral surgeons. There was no molar all judges agreed should be removed. There was a substantial variation between the individual GDP and oral surgeon concerning the relative weight they gave different diseases for the development of pathology. The GDPs, as a group, considered cyst formation and the oral surgeons pericoronitis to be the most influential pathological entity. Regarding the influence of the cues on the judgement of the need for removal, there was also a considerable variation in the dentists' individual judgements. As a group, the GDPs differentiated between two age-groups, and the oral surgeons differentiated between three age-groups. GDPs estimated the need for removal to be highest for distoangular and lowest for vertical molars, whereas oral surgeons gave the highest priority to removal of vertical and distoangular molars and the lowest priority to horizontal and mesioangular molars. Molars partially covered by soft tissue were given the highest priority for removal by both groups of judges. The mean proportion of variation for six diseases explained by the cues was high. Risk for molars of different angular positions and degrees of impaction was calculated from evidence in the literature. The risk, i.e. the odds ratio, for development of pathology was more than 22 times higher for molars partially covered by soft tissue compared with other degrees of impaction, and 5 to 12 times higher for distoangular molars compared with molars in other positions.
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- Yngve, Smedberg
(författare)
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On the reporting of dental health, time for dental care, and the treatment panorama : Methodological studies of measuring and analysing dental care outcomes within a Swedish Public Dental Service organization
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The thesis included five methodological studies and one caries epidemiological investigation, the general aim being to study how to measure and report dental health, time for dental care, treatment panorama, and dental care outcomes, within a Public Dental Service organization. The specific aims were to monitor dental clinic activities using a time study method, to apply time study results of a dental health-related patient group system for the 3-19 year age groups, and to compare time study results with corresponding results from computerized systems used for reporting dental care. Other specific aims were to compare longitudinal caries index data results between cohort and cross-sectional samples, to analyse caries index for extreme caries groups among adolescents leaving organized dental care, and — using time series methods — to analyse dental health development of the 15-19 year age groups. Results from the time studies portrayed the dental clinic as a working unit, showed that reported values can represent dental care only for intervention procedures, and indicated that clinic patterns were not adapted to the health situation of the patient groups. Longitudinal cohort attempts gave different values from those of the cross-sectional year classes, which should be the primary focus when presenting caries index mean values in dental health reviews. Caries freegroups from 15 to 19 years of age seem to be stable in their caries development in about 60%-80% of cases; while the 20% groups with the highest index values accounted for about 80% of all approximal lesions. In times of major economic adjustment, dental health for adolescents in Göteborg was an example of sustainable dental health development. A model system for monitoring, analysing, and reporting dental health and dental care outcomes within a dental care-giving organization calls for several conditions, for example, a dental healthrelated patient group system, and a rationale for the choice of dental team models. These areas could be gathered into a system where contemporary socio-economic factors and dental research results interact with performed dental care, and also with different methods for reporting and evaluating dental health, dental care costs, and the demand for dental care competence.
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