| 1. |
- Frisk, Fredrik, 1971, et al.
(författare)
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A 24-year follow-up of root filled teeth and periapical health amongst middle aged and elderly women in Göteborg, Sweden.
- 2005
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Ingår i: International endodontic journal. - : Wiley. - 0143-2885 .- 1365-2591. ; 38:4, s. 246-54
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Tidskriftsartikel (refereegranskat)abstract
- AIM: To describe the endodontic status amongst middle-aged and elderly women longitudinally and cross-sectionally over 24 years. METHODOLOGY: A random sample of 1462 women 38, 46, 50, 54 and 60 years old, living in Göteborg, Sweden, were sampled in 1968 for medical and dental examinations with a participation rate of 90.1%. The same women were re-examined in 1980 and 1992 together with new 38- and 50-year-old women. The dental examination consisted of questionnaires, clinical and panoramic radiological survey (OPG). The number of teeth, number of root filled teeth (RF) and number of teeth with periapical radiolucencies (PA) were registered. The RF and PA ratios were calculated. Cross-sectional data were analysed by means of anova and longitudinal data by a general linear model for repeated measures. Sample prevalences were compared and statistical inferences were made with the chi-squared test. In all analysis, the confidence interval (CI) regarded mean difference between groups (95% CI). RESULTS: The RF and PA ratio decreased over time as well as the frequency of edentulous subjects. Cross-sectional analysis revealed a minor increase in frequency of RF and PA and loss of teeth with age. Longitudinally, loss of teeth was evident in all cohorts. In addition, there was a trend of lower number of teeth with PA, and the RF ratio increased with age. CONCLUSIONS: The prevalence of periapical disease did not increase with age, probably as a result of root canal treatment and extractions. Data showed that the prevalence of RF teeth and teeth with PA decreased for comparable age cohorts during the 24-year follow-up.
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| 2. |
- Frisk, Fredrik, 1971
(författare)
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Epidemiological Aspects on Apical Periodontitis. Studies based on the Prospective Population Study of Women in Göteborg and the Population Study on Oral Health in Jönköping, Sweden
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The objectives of this thesis were to describe endodontic status in Swedish populations, to study clinical and socio-economic risk factors for apical periodontitis (AP) and to explore a possible association between AP and coronary heart disease (CHD). In papers I, III and IV the Prospective Study of Women in G?teborg (PSWG) was used. In paper I dentate women examined in 1968-69 (N=1220), 1980-81 (N=1023) and 1992-93 (N=867) were included for cross-sectional and longitudinal (N=586) analysis of endodontic status over 24 years in individuals aged 38-84 years. In papers III and IV a cross-sectional sample (N=844 and N=867, respectively) from 1992-93 was used for exploring associations between AP, socio-economic risk factors and CHD in multivariate logistic regression models. In paper II random samples of dentate individuals aged 20-70 years from the Population Study on Oral Health in J?nk?ping (PSJ) were used. The first examination in 1973 (N=498) was followed by new examinations in 1983 (N=530), 1993 (N=547) and 2003 (N=491). Full mouth radiographic examinations were restudied, yielding 3981 root filled teeth for the analysis. AP was recorded according to the Periapical Index (PAI) and the root filling quality was assessed with respect to length and seal. The association between root filling quality and AP was studied on the tooth-level as well as on the individual level. The results from multivariate logistic regression analysis did not reveal a significant association between AP and CHD and socio-economic risk factors and AP, respectively. The ratio of root filled teeth increased with age longitudinally and cross-sectionally, but decreased over time for comparable age groups. The ratio of AP increased with age cross-sectionally, but decreased with age longitudinally and for comparable age groups over time. Inadequate root filling quality was predictive of AP with an odds ratio of 4.5. The root filling quality was improved over time without a concomitant decrease in ratio of root filled teeth with AP.
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| 3. |
- Frisk, Fredrik, 1971, et al.
(författare)
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Socio-economic risk indicators for apical periodontitis.
- 2006
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Ingår i: Acta odontologica Scandinavica. - : Informa UK Limited. - 0001-6357 .- 1502-3850. ; 64:2, s. 123-8
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: The aim of this study was to reveal possible socio-economic risk indicators for apical periodontitis. MATERIAL AND METHODS: In 1992-93 a representative sample of women in Göteborg, Sweden, aged 38-84 years, participated in a medical and dental survey (n=981) which included dental and medical examinations and dental radiographic examination (OP). The dependent variable was apical periodontitis (AP=0, AP>0). The independent variables were age, number of teeth, number of restored teeth, number of root-filled teeth, number of teeth with carious lesions, satisfactory masticatory function, and dental esthetics as crude measures of self-reported dental health, dental anxiety, time elapsed since last visit to a dental office, regular dental visiting habits, smoking, alcohol habits, and marital status. A subjective evaluation of economy, health and life situation (acceptable or poor) was accounted for as socio-economic variables. The oldest age group, women born 1908, and edentulous individuals were omitted, leaving 844 subjects for analysis. Statistical analysis included multivariate logistic regression, chi-squared test, and independent t-test for comparison of group characteristics (AP=0 vs AP>0). RESULTS: For socio-economic variables there was a significant association between acceptable health and apical periodontitis (OR=1.72 (CI=1.09-2.70)). For oral-related variables, root-filled teeth (OR=1.17 (CI=1.10-1.23)) and teeth with carious lesions (OR=1.48 (CI=1.19-1.85)) were predictive of apical periodontitis. CONCLUSIONS: In the present study, socio-economic variables and dental visiting habits did not appear to have obvious implications for periapical health, whereas root-filled teeth and carious lesions were associated with apical periodontitis.
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| 4. |
- Frisk, Fredrik, 1971, et al.
(författare)
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Technical quality of root fillings and periapical status in root filled teeth in Jönköping, Sweden.
- 2008
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Ingår i: International endodontic journal. - : Wiley. - 1365-2591 .- 0143-2885. ; 41:11, s. 958-68
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Tidskriftsartikel (refereegranskat)abstract
- AIM: To study changes in technical quality of root fillings and periapical status in root filled teeth in random samples of 20 to 70 year-olds between 1973 and 2003. METHODOLOGY: Data from dentate subjects aged 20-70 years from examinations conducted in 1973 (n = 498), 1983 (n = 530), 1993 (n = 547) and 2003 (n = 491) were used for the analysis. Length of root fillings were measured on radiographs to the nearest 0.1 mm. Adequate seal was defined as a root filling without lateral and/or apical voids. Periapical status was assessed according to the periapical index. All observations were made by one calibrated observer registered from full mouth radiographic examinations. Teeth with root fillings ending within the canal without lateral or apical voids were considered adequate. The association between root filling quality and periapical status was analysed by means of the Chi-squared test and a multilevel logistic regression analysis. RESULTS: Adequately root filled teeth had a significantly lower frequency of apical periodontitis than inadequately root filled teeth (11.8% vs. 22.8%). The frequency of technically adequate root fillings increased statistically significant from 1973 (23.7%) to 2003 (36.4%) without a concomitant improvement of the periapical status in root filled teeth over time (24.5% vs. 24.6%). CONCLUSIONS: This study reports on an improving technical quality of root fillings over time, without a concomitant improvement of the periapical status in root filled teeth. A larger proportion of treated molars over time may be of importance for the result.
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| 5. |
- Gustafsson, Fredrik, et al.
(författare)
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On Threshold Optimization in Fault Tolerant Systems
- 2008
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Ingår i: Proceedings of the 17th IFAC World Congress. ; , s. 7883-7888
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Konferensbidrag (refereegranskat)abstract
- Fault tolerant systems are considered, where a nominal system is monitored by a fault detection algorithm, and the nominal system is switched to a backup system in case of a detected fault. Conventional fault detection is in the classical setting a trade-off between detection probability and false alarm probability. For the considered fault tolerant system, a system failure occurs either when the nominal system gets a fault that is not detected, or when the fault detector signals an alarm and the backup system breaks down. This means that the trade-off for threshold setting is different and depends on the overall conditions, and the characterization and understanding of this trade-off is important. It is shown that the probability of system failure can be expressed in a general form based on the probability of false alarm and detection power, and based on this form the influence ratio is introduced. This ratio includes all information about the supervised system and the backup system that is needed for the threshold optimization problem. It is shown that the influence ratio has a geometrical interpretation as the gradient of the receiver operating characteristics (ROC) curve at the optimal point, and furthermore, it is the threshold for the optimal test quantity in important cases.
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| 6. |
- Heintz, Fredrik, 1975-, et al.
(författare)
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FlexDx: A Reconfigurable Diagnosis Framework
- 2008
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Ingår i: Proceedings of the 19th International Workshop on Principles of Diagnosis (DX).
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Konferensbidrag (refereegranskat)abstract
- Detecting and isolating multiple faults is a computationally intense task which typically consists of computing a set of tests, and then computing the diagnoses based on the test results. This paper describes FlexDx, a reconfigurable diagnosis framework which reduces the computational burden by only running the tests that are currently needed. The method selects tests such that the isolation performance of the diagnostic system is maintained. Special attention is given to the practical issues introduced by a reconfigurable diagnosis framework such as FlexDx. For example, tests are added and removed dynamically, tests are partially performed on historic data, and synchronous and asynchronous processing are combined. To handle these issues FlexDx uses DyKnow, a stream-based knowledge processing middleware framework. The approach is exemplified on a relatively small dynamical system, which still illustrates the computational gain with the proposed approach.
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| 7. |
- Krysander, Mattias, 1977-, et al.
(författare)
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Dynamic Test Selection for Reconfigurable Diagnosis
- 2008
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Ingår i: Proceedings of the 47th IEEE Conference on Decision and Control. - : IEEE. - 9781424431243 - 9781424431236 ; , s. 1066-1072
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Konferensbidrag (refereegranskat)abstract
- Detecting and isolating multiple faults is a computationally intense task which typically consists of computing a set of tests, and then computing the diagnoses based on the test results. This paper proposes a method to reduce the computational burden by only running the tests that are currently needed, and dynamically starting new tests when the need changes. A main contribution is a method to select tests such that the computational burden is reduced while maintaining the isolation performance of the diagnostic system. Key components in the approach are the test selection algorithm, the test initialization procedures, and a knowledge processing framework that supports the functionality needed. The approach is exemplified on a relatively small dynamical system, which still illustrates the complexity and possible computational gain with the proposed approach.
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| 8. |
- Larsson, Bengt, et al.
(författare)
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Molecular oxygen in the rho Ophiuchi cloud
- 2007
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Ingår i: Astronomy & Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 466:3, s. 5-
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Tidskriftsartikel (refereegranskat)abstract
- Context: Molecular oxygen, O2, has been expected historically to be an abundant component of the chemical species in molecular clouds and, as such, an important coolant of the dense interstellar medium. However, a number of attempts from both ground and from space have failed to detect O2 emission.Aims: The work described here uses heterodyne spectroscopy from space to search for molecular oxygen in the interstellar medium. Methods: The Odin satellite carries a 1.1 m sub-millimeter dish and a dedicated 119 GHz receiver for the ground state line of O2. Starting in 2002, the star forming molecular cloud core ρ Oph A was observed with Odin for 34 days during several observing runs.Results: We detect a spectral line at v_LSR =+3.5 km s-1 with Δ v_FWHM=1.5 km s-1, parameters which are also common to other species associated with ρ Oph A. This feature is identified as the O2 (NJ = 11 - 1_0) transition at 118 750.343 MHz.Conclusions: The abundance of molecular oxygen, relative to H{2} , is 5 × 10-8 averaged over the Odin beam. This abundance is consistently lower than previously reported upper limits.Based on observations with Odin, a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes) and Centre National d'Étude Spatiale (CNES). The Swedish Space Corporation has been the industrial prime contractor and also is operating the satellite. Appendix A is only available in electronic form at http://www.aanda.org
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| 9. |
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