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- Bryndahl, Fredrik, 1963-
(författare)
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Temporomandibular joint disk displacement and subsequent adverse mandibular growth : a radiographic, histologic and biomolecular experimental study
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The mandibular condyles represent important growth sites within the facial skeleton. Condylar growth is not a pacemaker of mandibular development, but it provides regional adaptive growth that is of considerable clinical significance, as the condyle’s upward and backward growth movement regulates the anteriorly and inferiorly directed displacement of the mandible as a whole.Orthopedic problems of the temporomandibular joint (TMJ), such as displacement of the TMJ disk, are common in the adolescent population. Clinical studies of mandibular asymmetry and mandibular retrognathia in adults as well as in children and adolescents, have reported an association with coexisting non-reducing displacement of the TMJ disk without identifying the cause and effect. Through experimental studies causality has been established, and unilateral affliction during growth has been shown to retard ipsilateral mandibular development with facial asymmetry as the sequel. It was hypothesized that bilateral non-reducing TMJ disk displacement during growth would impair mandibular development bilaterally, resulting in mandibular retrognathia. TMJ disk displacement has repeatedly been demonstrated to induce histological reactions of the condylar cartilage. An additional assumption was therefore that a non-deranged TMJ disk function is crucial for the maintenance of the growing condyle’s biophysical environment, and that a connection ought to exist between the amount of condylar cartilage changes caused by TMJ disk displacement and the amount of subsequent adverse mandibular growth. It was also hypothesized that non-reducing displacement of the TMJ disk in growing individuals would result in qualitative and quantitative changes of the condylar subchondral bone.An improved experimental cephalometric method was developed in order to optimize the reliability of longitudinal radiographic evaluation of fast growing small animals. Bilateral non-reducing TMJ disk displacement was surgically created in ten growing New Zealand White rabbits, with ten additional rabbits serving as a sham operated control group. The amount and direction of craniofacial growth was followed over time in serial cephalograms, aided by tantalum implants in the jaws. The study period was chosen to correspond to childhood and adolescence in man. The assessed growth of each side of the mandible was correlated to the histological feature of ipsilateral condylar cartilage at the end of the growth period. The amount and composition of subchondral bone from three regions of interest in the condyle, and the expression of local growth factors in the adjacent condylar cartilage was evaluated.The results verified that bilateral non-reducing TMJ disk displacement retarded mandibular growth bilaterally; the extent corresponding to mandibular retrognathia in man. Displacement of the TMJ disk during the growth period induced condylar cartilage adaptive reactions that were associated with both an adverse amount and direction of mandibular growth, manifesting in a retrognathic mandibular growth pattern. Growth impairment fluctuated over time, with the most striking retardation occurring during periods of increased general growth, implying a local growth reduction explicitly counteracting general hormonal growth acceleration. A significant decrease of the total amount of subchondral bone, in spite of a general increase of new bone formation in the experimental condyles, pointed to a reparative compensation for an extensive resorption of subchondral bone due to displacement of the TMJ disk, but not to the extent that normal growth would be maintained. These results constitute an explanation for the adverse mandibular development following non-reducing TMJ disk displacement in growing individuals.This project has shown that non-reducing displacement of the TMJ disk during growth has significant consequences on facial development. The findings strongly advocate early and accurate diagnosis and treatment of TMJ disk displacement in the adolescent population, thereby presumably reducing the need for future orthodontic and surgical craniofacial corrective therapy. The results furthermore enhance the need for full appraisal of TMJ disk function in the adolescent population during orthodontic functional therapy, as the condylar cartilage and subchondral bone reactions to a concomitantly displaced non-reducing TMJ disk must be expected to interfere with the intended growth stimulating treatment. The findings of intact articular layers in spite of gross histological and morphological soft and hard tissue changes as a sequel to TMJ disk displacement in growing individuals, implicate a clinical risk of false positive radiographic diagnosis of degenerative changes of the TMJ in children and adolescents.
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| 2. |
- Persson, G. Rutger, et al.
(författare)
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The impact of ethnicity, gender, and marital status on periodontal and systemic health of older subjects in the Trials to Enhance Elders' Teeth and Oral Health (TEETH).
- 2004
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Ingår i: Journal of Periodontology. - 0022-3492 .- 1943-3670. ; 75:6, s. 817-23
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Few studies have examined the association between periodontitis risk, gender, and marital status in older adults. The purpose of this study was to assess if the oral health status of older subjects could be explained by differences in: 1) marital status; 2) gender; and 3) ethnicity.METHODS: Clinical and radiographic periodontal oral conditions were studied in 701 older subjects from the TEETH clinical trial. Medical conditions as well as ethnic and marital status and smoking habits were considered.RESULTS: A total of 89 married couples were identified; 40.7% of these were of European descent and 48.1% of Chinese descent. The mean age was 67.7 years (SD +/- 4.7). The men were older than the women (mean difference: 1.5 years, SD +/- 4.6, 95% confidence interval [CI]: 0.5 to 2.5, P<0.01). No significant differences in periodontal conditions were found between spouses or by marital status. Chinese descent was associated with a higher risk for periodontitis, regardless of marital status (odds ratio: 1.5, 95% CI: 1.05 to 2.04, P<0.03).CONCLUSIONS: 1) Married couples have similar social habits, similar oral health perceptions, and similar patterns of periodontal disease. 2) Dental studies including married couples do not bias data for married subjects as such. 3) Marital status has a limited impact on periodontal health but may have a greater impact on several systemic conditions, especially in widowed, divorced, or never married women. 4) Older Chinese subjects perceive themselves as being at lower risk for periodontitis but have more objective signs of periodontitis than older subjects of European descent.
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| 3. |
- Ravon, Nicolas A, et al.
(författare)
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Signs of carotid calcification from dental panoramic radiographs are in agreement with Doppler sonography results.
- 2003
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Ingår i: Journal of Clinical Periodontology. - 0303-6979 .- 1600-051X. ; 30:12, s. 1084-1090
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Duplex ultrasonography (DS) is a frequently used noninvasive method for assessing carotid artery stenosis. The level of agreement between panoramic radiographs (PMX) findings of radiopacities in the area of C3-C4 and DS results has not been established.AIMS: (1) to examine the level of agreement between DS results and PMX signs of carotid calcification and (2) to evaluate the association between periodontitis and DS results.MATERIAL AND METHODS: Eighty-three subjects who had received a DS assessment at the University of Washington Medical Center within 36 months volunteered for a periodontal examination, including assessments of probing pocket depth (PPD), attachment level (PAL), evidence of bleeding on probing and bone loss from PMX. Two examiners independently analyzed the radiographs for evidence of carotid calcifications. The distance between the cemento-enamel junction (CEJ) to bone level (BL) CEJ-BL was used to assess alveolar bone loss as a criteria for periodontitis.RESULTS: Twenty-nine subjects (34.9%) presented with positive DS readings. The Mantel-Haentszel common odds ratio estimate for a positive DS score and periodontitis (> 30% of teeth with distance CEJ-BL > or = 4.0 mm) was 38.4 (95% CI: 10.6-138.7, p < 0.0001). For nonsmokers only (n = 72) the odds ratio was 43.0 (95% CI: 16.7-1178.0, p < 0.0001). Evidence of bleeding on probing was 16% of sites both in the DS-positive and -negative subjects. Subjects with a positive DS result had significantly more teeth with clinical evidence of attachment loss > or = 5.0 mm (p < 0.001). The odds ratio of having periodontitis (CEJ-BL > or = 4.0 mm at > or = 30% of the teeth) and medical records confirmed diagnosis of either a stroke or an infarct or both was 7.8 (95% CI: 2.6-23.8, p < 0.001).CONCLUSIONS: Subjects with positive DS readings of the carotid arteries due to calcified arterial plaque are accurately detected by means of conventional PMX. The likelihood of being DS positive and having radiographic evidence of periodontitis is high. A dose-response relationship between the extent of carotid calcification and severity of periodontitis was demonstrated, supporting the hypothesis of an association between periodontitis and cardiovascular diseases.
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| 4. |
- Salojarvi, Jarkko, et al.
(författare)
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Genome sequencing and population genomic analyses provide insights into the adaptive landscape of silver birch
- 2017
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Ingår i: Nature Genetics. - : NATURE PUBLISHING GROUP. - 1061-4036 .- 1546-1718. ; 49:6, s. 904-912
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Tidskriftsartikel (refereegranskat)abstract
- Silver birch (Betula pendula) is a pioneer boreal tree that can be induced to flower within 1 year. Its rapid life cycle, small (440-Mb) genome, and advanced germplasm resources make birch an attractive model for forest biotechnology. We assembled and chromosomally anchored the nuclear genome of an inbred B. pendula individual. Gene duplicates from the paleohexaploid event were enriched for transcriptional regulation, whereas tandem duplicates were overrepresented by environmental responses. Population resequencing of 80 individuals showed effective population size crashes at major points of climatic upheaval. Selective sweeps were enriched among polyploid duplicates encoding key developmental and physiological triggering functions, suggesting that local adaptation has tuned the timing of and cross-talk between fundamental plant processes. Variation around the tightly-linked light response genes PHYC and FRS10 correlated with latitude and longitude and temperature, and with precipitation for PHYC. Similar associations characterized the growth-promoting cytokinin response regulator ARR1, and the wood development genes KAK and MED5A.
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