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- af Geijersstam, E, et al.
(author)
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Mercury uptake and kinetics after ingestion of dental amalgam
- 2001
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In: Journal of dental research. - : SAGE Publications. - 0022-0345 .- 1544-0591. ; 80:9, s. 1793-1796
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Journal article (peer-reviewed)abstract
- The aim of the present study was to investigate the G-I uptake of mercury (Hg) after intake of a single dose of amalgam-Hg, followed by pharmacokinetic analysis of the data. Eleven volunteers without amalgam fillings ingested 1.00 g amalgam powder. Hg in plasma vs. time was analyzed with a two-compartment model by means of mixed-effects modeling. A fraction of the absorption rate of Hg to the central compartment was inversely proportional to the plasma ferritin levels. The population mean half-life of the terminal phase of Hg in plasma was 37 days, with a considerable standard deviation in the population. The absorbed fraction of the administered dose was estimated to be about 0.04%. It is concluded that the G-I uptake of Hg is of quantitative importance during dental treatment.
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| 2. |
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| 3. |
- Berggren, Ulf, 1948, et al.
(author)
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Relaxation vs. cognitively oriented therapies for dental fear.
- 2000
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In: Journal of dental research. - 0022-0345 .- 1544-0591. ; 79:9, s. 1645-51
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Journal article (peer-reviewed)abstract
- Cognitive therapy has been reported for the treatment of dental phobia, but comparisons with other behavioral treatments are scarce. This study investigated the outcome of two modes of treatment for phobic dental fear. Relaxation and cognitively oriented therapy were compared in a sample of 112 adult fearful dental patients. The patient made questionnaire assessments of background and outcome variables, and the specialist dentist rated successful/non-successful outcome. It was shown that a higher number of patients who received cognitively oriented therapy completed the treatment program, while anxiety was more reduced among patients who received relaxation-oriented therapy. Dropout during the initial phobia therapy with a psychologist was related to lower motivation (willingness to engage in treatment), while failures during dental treatment after the completion of therapy were related to higher levels of general fear and anxiety. A multiple logistic regression model explaining 67% of the variance revealed that the risk of failure was only slightly increased by general fears, while patients with low (below median) motivation ran a 3.6-times-higher risk of dropping out. In conclusion, it was shown that the two treatment methods were both effective in reducing dental phobic reactions. However, while cognitively oriented therapy resulted in a higher number of patients completing therapy, relaxation-oriented treatment generally resulted in a more significant reduction in dental fear as well as in general anxiety and fear. Motivation was found to be a significant predictor of successful treatment outcome.
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| 5. |
- Emami, Nazanin, et al.
(author)
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Cure kinetic behavior of light-cure dental composites
- 2003
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In: Journal of Dental Research. - 0022-0345 .- 1544-0591. ; :Suppl.
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Journal article (other academic/artistic)abstract
- Objective: To investigate differences in cure kinetic behaviours of different photo and co-initiator systems used in dental light-cure composites. Method: A resin system (50 wt.% of bisGMA and 50 wt.% of TEGDMA) was mixed with either campherquinone (CQ) or 1-phenyl-1,2-propanedione (PPD) as photo-initiator. N,N-dimethyl-p-aminobenzoic acid ethylester (DABE), N,N-cyanoethylmethylaniline (CEMA), N,N-diethanol-p-toluidine (DEPT) and 2-dimethylaminoethyl methacrylate (DMAEMA) were used as co-initiators respectively. Complex cure behaviour of 24 experimental mixtures made from 2 photoinitiators, 4 co-initiators, 3 curing light/time was studied with differential Scanning Calorimetery (DSC). Six specimens of each composition were cured either with 800 mW/cm2 for 40 s, soft start curing for 60 s or LED for 40 s. The DSC results were analysed using ANOVA and Duncan's multiple range test and regular t-test. Result: Rate of polymerisation was significantly (p<0.05) higher when materials were cured with 800 mW/cm2 compare to soft start and LED curing methods when the final degree of conversion values did not differ significantly (p>0.05). Compared to campherquinone, the photo-initiator PPD reduced the maximal DC% and rate of the polymerisation significantly (p<0.05). PPD was not a suitable photo-initiator when cured with LED since the blue spectra emitting from the used LED lamp does not cover the optimal activation wavelength for PPD properly. The highest DC% measured at the end of curing was for CQ & DABE 74%±1 cured with 800 mw/cm2 for 40s and the lowest was for PPD&DMAEMA 22%±1.1 when material was cured with LED for 40s. Use of DEPT resulted in significant decreases in degree of conversion (p<0.05). Conclusion: It was concluded that intrinsic slow cure might be obtained with certain compositions of photo & co-initiators and curing methods without impairing the final extent of degree polymerzation.
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| 6. |
- Emami, Nazanin, et al.
(author)
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Effect of light intensities variations on bulk curing of dental composites
- 2002
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In: Journal of Dental Research. - 0022-0345 .- 1544-0591. ; 81:Suppl. 1
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Journal article (peer-reviewed)abstract
- The light intensity used during curing of light curable dental composites is believed to affect the residual stress level. In this study we tested the hypothesis that low light intensity and long but clinically acceptable light curing time, can produce composites with physical/clinical properties (e.g. volumetric shrinkage, linear contraction stress, degree of conversion (DC%) and Young's modulus) comparable to those of high light intensity cured composites. Methods: Two dental composites, Z100 and Z250, were investigated. Specimens were cured with light intensities of 200, 450 and 800 mW/cm2 for 140, 60 and 35 s from a distance of 7 mm. Linear contraction strains were measured with strain-gages attached to stainless steel rings serving as molds (8 mm in diameter and 4 mm high). DC% was measured at the top and the bottom of samples as well through the bulk using FTIR. Volumetric polymerization shrinkage was determined using a water displacement method. Young's modulus was determined in tension on composite specimens with dimensions of 8 x 50 x 1 mm. Results: Polymerization stress level decreased significantly (p<0.05) when cured with 200 mW/cm2 rather than with 800 mW/cm2. Reduction in light intensity did not decrease the DC% values significantly, nevertheless the most dramatic differences existed between top and bottom surfaces (p<0.05) rather than among curing groups. Measured modulus and volumetric shrinkage values were no significantly different (p>0.05) between different light intensity groups. Conclusion: Low light intensity decreased the residual stress and DC% values (through the depth of cure) significantly (p<0.05), but did not significantly affect the Young's modulus and the volumetric shrinkage values. The lower residual stress values, reflected by lower strain levels in the metal rings used during measurement, suggest that more stress relaxation occurs in the low light intensity group during cure. Our results support the proposed hypothesis
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| 9. |
- Eriksson, P O, et al.
(author)
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Co-ordinated mandibular and head-neck movements during rhythmic jaw activities in man.
- 2000
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In: Journal of Dental Research. - : SAGE Publications. - 0022-0345 .- 1544-0591. ; 79:6, s. 1378-1384
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Journal article (peer-reviewed)abstract
- Recent observations in man of concomitant mandibular and head movements during single maximal jaw-opening/-closing tasks suggest a close functional relationship between the mandibular and the head-neck motor systems. This study was aimed at further testing of the hypothesis of a functional integration between the human jaw and neck regions. Spatiotemporal characteristics of mandibular and associated head movements were evaluated for 3 different modes of rhythmic jaw activities: self-paced continuous maximal jaw-opening/-closing movements, paced continuous maximal jaw-opening/-closing movements at 50 cycles/minute, and unilateral chewing. Mandibular and head-neck movements were simultaneously recorded in 12 healthy young adults, by means of a wireless opto-electronic system for 3-D movement recordings, with retro-reflective markers attached to the lower (mandible) and upper (head) incisors. The results showed that rhythmic mandibular movements were paralleled by head movements. An initial change in head position (head extension) was seen at the start of the first jaw-movement cycle, and this adjusted head position was retained during the following cycles. In addition to this prevailing head extension, the maximal jaw-opening/-closing cycles were paralleled by head extension-flexion movements, and in general the start of these head movements preceded the start of the mandibular movements. The results support the idea of a functional relationship between the temporomandibular and the cranio-cervical neuromuscular systems. We therefore suggest a new concept for human jaw function, in which "functional jaw movements" are the result of activation of jaw as well as neck muscles, leading to simultaneous movements in the temporomandibular, atlanto-occipital, and cervical spine joints.
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| 10. |
- Gabre, Pia, et al.
(author)
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Move of adults with mental retardation from institutions to community-based living: changes in the oral microbiological flora.
- 2001
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In: Journal of dental research. - : SAGE Publications. - 0022-0345 .- 1544-0591. ; 80:2, s. 421-426
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Journal article (peer-reviewed)abstract
- In the Western world, the policy of deinstitutionalization and integration of individuals with mental retardation is generally accepted. We tested the hypothesis that de-institutionalization may lead to changes of habits with a potential to influence oral health. When 57 adults with mental retardation moved from an institution to community-based living, their oral hygiene habits, gingival bleeding, and a three-day food record were registered one month before and 9 and 21 months after the move. Mutans streptococci and lactobacilli in saliva, P. intermedia/P. nigrescens, P. gingivalis, and A. actinomycetemcomitans in supragingival plaque, and C. albicans on mucous membranes were analyzed. After 21 months of community-based living, fewer persons showed high classes of mutans streptococci, growth of P. intermedia/P. nigrescens, and high frequency of sucrose intake, and more subjects showed growth of C. albicans. In a short perspective, the indicators of oral diseases suggest an unchanged or lower risk of oral diseases after the de-institutionalization of individuals with moderate or severe mental retardation.
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