On the natural course of oral lichen lesions in a Swedish population-based sample

OBJECTIVES: The aim was to assess the natural course of oral lichen lesions (OLL) among unselected, non-consulting individuals. SUBJECTS AND METHODS: A cohort of 327 subjects with OLL, confirmed in 1973-1974 during a population-based survey in two Swedish municipalities, was followed through January 2002 via record linkages with nationwide and essentially complete registers. A sample of 80 drawn from the 194 surviving subjects who still resided in the area in 1993-1995 was invited for interview and oral re-examination. RESULTS: At the end of follow-up, one case of oral cancer was detected, while 0.4 were expected. The overall mortality among subjects with OLL was not significantly different from that in the 15,817 OLL-free subjects who participated in the initial population based survey in 1973-1974. The lesion had disappeared in 14 (39%) of 36 re-examined subjects with white OLLs in 1973-1974, and four (11%) had transformed into red types. In the corresponding group of 19 with red forms initially, five (26%) had become lesion free and four (21%) had switched to white types. Although the cohort size does not permit firm conclusions regarding oral cancer risk, the natural course over up to 30 years appears to be benign in the great majority.     

Increased risk for tooth extraction in primary hyperparathyroidism and hypercalcemia: a population study

Clinical Oral Investigations - The aim of this study was to analyze dental comorbidities in untreated primary hyperparathyroidism (pHPT). Patients with pHPT subjected to parathyroidectomy (PTX) at...     

Transport of methylmercury and inorganic mercury to the fetus and breast-fed infant

It is well established that methylmercury (MeHg) and mercury vapor pass the placenta, but little is known about infant exposure via breast milk. We measured MeHg and inorganic mercury (I-Hg) in blood of Swedish mothers (n = 20) and their infants, as well as total mercury (T-Hg) in breast milk up to 13 weeks postpartum. Infant blood MeHg was highly associated with maternal blood MeHg at delivery, although more than twice as high. Infant MeHg decreased markedly until 13 weeks of age. Infant blood I-Hg was associated with, and about as high as, maternal blood I-Hg at delivery. Infant I-Hg decreased until 13 weeks. In breast milk, T-Hg decreased significantly from day 4 to 6 weeks after delivery but remained unchanged thereafter. At 13 weeks, T-Hg in breast milk was associated with infant MeHg but not with maternal MeHg. Conversely, T-Hg in breast milk was associated with maternal I-Hg but not with infant I-Hg. From the findings of the present study in which the exposure to both MeHg and I-Hg was low, we conclude that the exposure to both forms of mercury is higher before birth than during the breast-feeding period, and that MeHg seems to contribute more than I-Hg to infant exposure postnatally via breast milk.     

Gastrointestinal absorption of metallic mercury

The absorption of mercury from the gastrointestinal systems of 7 subjects, of whom none had any amalgam fillings, was examined in this study. The authors obtained quantitative information about mercury concentration in plasma and duodenal fluid after the gastrointestinal systems of the subjects were exposed to liquid elemental mercury enclosed in rubber balloons (i.e., approximately 20 g of mercury), using a standard procedure followed for the sampling of bile. Plasma samples were collected prior to exposure, as well as up to 10 d following exposure, and duodenal fluid was collected 1 h, 2 h, 4 h, and 6 h during the intubation process. The authors studied the kinetics of dissolution in vitro by leaching elemental liquid mercury and mercuric chloride. The results of this study supported the hypothesis that metallic mercury is oxidized in the gastrointestinal tract. In addition, the authors determined that duodenal intubation, while using liquid metallic mercury in rubber bags, resulted in the diffusion of minor amounts of atomic elemental mercury through the rubber walls. The absorbed amount of mercury that reached the central circulation was comparable to a daily dose of mercury from dental amalgam in the amalgam-bearing population.     

Computer aided analysis of digitized dental stone replicas by dental CAD/CAM technology.

OBJECTIVES: To determine the reproducibility of digitized dental stone replicas compared to the master model and the reliability of the computer aided analysis. METHODS: Four master dies, prepared for complete crowns were fabricated in presintered yttria-stabilized tetragonal zirconia (Y-TZP). Eight vinyl polysiloxane impressions (PROVIL novo; Heraeus Kulzer) were taken of each die and stone replicas were poured in type IV stone (Vel-Mix Stone; Kerr). The master dies and the stone replicas were digitized in a touch-probe scanner (Procera Forte; Nobel Biocare AB), to create triangulated surface-models. The point-cloud from the first of the repeated digitizations of each master die was used as CAD-reference-models (CRM). Discrepancies between the points in the triangulated surface-models and the corresponding CRM were measured by a matching-software (CopyCAD 6.504 SP2; Delcam Plc). The distribution of the discrepancies was analyzed and presented in color-difference-maps. RESULTS: The precision of the measuring method, presented as the repeatability coefficient, ranged between 7 and 16 microm (entire surface), whereas the analysis of the stone replicas revealed a precision (repeatability coefficient) ranging from 19 to 26 microm. The accuracy of the replica to master (the mean discrepancy) ranged from 0.5 to 2.0 microm (95% confidence interval 1.5-2.9 microm). SIGNIFICANCE: The greatest precision of the measurement was seen in the jacket surface of the die. The size of the stone replicas varied and the repeatability coefficient was on average 15 microm (2-25 microm) greater for the replica-to-master alignment than the repeated digitizations of the master.     

A multidisciplinary clinical study of patients suffering from illness associated with mercury release from dental restorations: psychiatric aspects

The aim of this study was to map the psychological/psychiatric, odontological and medical aspects of patients with symptoms allegedly related to the side-effects of mercury in dental fillings. A total of 67 consecutive patients and 64 controls matched for age, sex and residential area were included in the study. The most striking result was the high prevalence of psychiatric disorders in the patients (89%) compared to the controls (6%), predominantly somatoform disorders. The personality traits differentiating the patients according to the Karolinska Scales of Personality (KSP) were somatic anxiety, muscular tension, psychasthenia and low socialization. More patients than controls showed alexithymic traits. The prevalence of diagnosed somatic diseases was higher, but not sufficiently so to explain the large difference in perceived health. The multiple symptoms and signs of distress displayed by the patients could not be explained either by the odontological data or by the medical examination. Our data indicate that the patients show sociodemographic and clinical patterns similar to those of somatizing patients. The medicalization of the suffering of these patients and the neglect of psychiatric problems prevent the use of appropriate psychotherapeutic approaches.     

Biological and physicochemical properties of carbon-graphite fibre-reinforced polymers intended for implant suprastructures

The aim of this study was to determine water sorption, water solubility, dimensional change caused by water storage, residual monomers, and possible cytotoxic effects of heat-polymerized carbon-graphite fibre-reinforced composites with different fibre loadings based on methyl methacrylate/poly(methyl methacrylate) (MMA/PMMA) and the copolymer poly (vinyl chloride-co-vinyl acetate). Two different resin systems were used. Resin A contained ethylene glycol dimethacrylate (EGDMA) and 1,4-butanediol dimethacrylate (1,4-BDMA); the cross-linker in Resin B was diethylene glycol dimethacrylate (DEGDMA). The resin mixtures were reinforced with 24, 36 and 47 wt% surface-treated carbon-graphite fibres. In addition, polymer B was reinforced with 58 wt% fibres. Water sorption was equal to or below 3.34±1.18 wt%, except for the 58 wt% fibre loading of polymer B (5.27±1.22 wt%). Water solubility was below 0.36±0.015 wt%, except for polymer B with 47 and 58 wt% fibres. For all composites, the volumetric increase was below 0.01±0.005 vol%. Residual MMA monomer was equal to or below 0.68±0.05 wt% for the fibre composites. The filter diffusion test and the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) assay demonstrated no cytotoxicity for the carbon-graphite fibre-reinforced composites, and residual cross-linking agents and vinyl chloride were not detectable by high-performance liquid chromatography (HPLC) analysis.     

A three-dimensional evaluation of a laser scanner and a touch-probe scanner

STATEMENT OF PROBLEM: The fit of a dental restoration depends on quality throughout the entire manufacturing process. There is difficulty in assessing the surface topography of an object with a complex form, such as teeth, since there is no exact reference form. PURPOSE: The purpose of this study was to determine the repeatability and relative accuracy of 2 dental surface digitization devices. A computer-aided design (CAD) technique was used for evaluation to calculate and present the deviations 3-dimensionally. MATERIAL AND METHODS: Ten dies of teeth prepared for complete crowns were fabricated in presintered yttria-stabilized tetragonal zirconia (Y-TZP). The surfaces were digitized 3 times each with an optical or mechanical digitizer. The number of points in the point clouds from each reading were calculated and used as the CAD reference model (CRM). Alignments were performed by registration software that works by minimizing a distance criterion. In color-difference maps, the distribution of the discrepancies between the surfaces in the CRM and the 3-dimensional surface models was identified and located. RESULTS: The repeatability of both scanners was within 10 microm, based on SD and absolute mean values. The qualitative evaluation resulted in an even distribution of the deviations in the optical digitizer, whereas the dominating part of the surfaces in the mechanical digitizer showed no deviations. The relative accuracy of the 2 surface digitization devices was within +/- 6 microm, based on median values. CONCLUSION: The repeatability of the optical digitizer was comparable with the mechanical digitization device, and the relative accuracy was similar.     

Pharmacokinetics of triclosan following oral ingestion in humans

The number of personal hygiene products containing triclosan has increased rapidly during the last decade, and triclosan is one of the most common antibacterial compounds used in dentifrices today. However, the extent of triclosan exposure has not yet been well described. The potential risks of generating triclosan-resistant pathogenic microorganisms or of the selection of resistant strains are some areas of concern. The aim of the present study was to (1) obtain information on baseline levels of triclosan in plasma and urine, and (2) study the pharmacokinetic pattern of triclosan after a single-dose intake. Ten healthy volunteers were exposed to a single oral dose of 4 mg triclosan by swallowing an oral mouthwash solution. Triclosan in plasma and urine was followed before and up to 8 d after exposure. Triclosan levels in plasma increased rapidly, with a maximum concentration within 1 to 3 h, and the terminal plasma half-life was 21 h. The major fraction was excreted within the first 24 h. The accumulated urinary excretion varied between the subjects, with 24 to 83% of the oral dose being excreted during the first 4 d after exposure. In conclusion, triclosan appears to be readily absorbed from the gastrointestinal tract and has a rapid turnover in humans. The high lipid solubility of the substance gives rise to questions regarding distribution properties and accumulation. The findings of the present study form a basis for greater understanding of the toxicokinetic properties of triclosan in humans.