Proceedings of the Finnish Dental Society. Suomen Hammaslaakariseuran toimituksia最新文献

Finland is poor in selenium. Selenium deficit leads to muscular dystrophy in animals. Since 1962, selenium has been added in Finland to some animal foodstuffs, since 1968 to all animal foodstuffs. Addition of selenium to fertilizers started in 1984. Intake of selenium by man and cattle today is roughly 1.0 times higher than it was before selenium supplementation. Collagen is the most important component of the organic matrix of the tooth. Selenium can replace sulphur in bonds of collagen. The resulting bond is stronger than a sulphur bond. Since selenium supplementation, the conditions of the teeth of children and young people has improved considerably. The author believes that selenium supplementation has reduced the incidence of caries in young Finns.

The vascular changes of the pulpal vessels in experimentally induced pulpotomy in dog tooth were investigated using microcorrosive resin casts technique and scanning electron microscopic examination. The pulpal tissues of the permanent mandibular molars were amputated and then dressed with calcium hydrate. At one to eight weeks after pulpotomy, the experimental teeth were prepared for resin casts of pulpal vessels with hard tissues. One week after pulpotomy, a concave region, which was supposed to be due to the compression by the calcium hydrate, was found in the newly formed pulpal vascular network. Around the concave region was a flat, dense capillary network. In eight weeks, the thick dentin bridge was formed in close proximity to the amputated pulpal surface. The vascular network just beneath the dentin bridge changed into similar features in the three layers of the normal pulpal vascular architecture, which are (i) terminal capillary network (TCN), (ii) capillary network (CN), and (iii) venular network (VN) and which distributed in the superficial layer of the pulpal vessels.

One of the initial events in pulpal inflammation has been characterized as neurogenic inflammation: the release of neuropeptides following excitation of sensory C-fibers by noxious stimuli which alters microcirculatory parameters, that is, vasodilation and plasma extravasation. Thus, the purpose of the study was to investigate the effect of capsaicin on pulpal blood flow (PBF) with the aim of understanding neurogenic inflammation in the dental pulp by characterizing the response of the pulpal vasculature to repeated applications of various concentrations of capsaicin. Experiments were performed on canine teeth of cats anesthetized with sodium pentobarbital. PBF was measured by the laser Doppler flowmeter following the application of capsaicin into the dentinal cavities of the canine teeth. The increases of PBF to capsaicin were 31.8 +/- 6.3% (n = 6) and 54.2 +/- 6.2% (n = 9), for 1 microM and 100 microM capsaicin, respectively. The increase of PBF peaked at about 50 sec after the capsaicin placement and the PBF returned to control level within 20 min following capsaicin removal. Four repeated applications of 1 microM capsaicin caused a small change in the peak PBF amplitude. In contrast, a second application of 100 microM capsaicin caused a significantly smaller increase of PBF than the first application (26.8 +/- 6.4% vs. 54.2 +/- 6.2%). Results of the present study show that local application of capsaicin caused the increase of PBF and that repeated capsaicin stimulations inhibited PBF responses. Smaller PBF increases in response to high concentrations of capsaicin also suggested the depletion of vasoactive substances, e.g. substance P, from the sensory nerve terminals, which appears to be dose-dependent. The PBF response to capsaicin suggests that neurogenic inflammation in the dental pulp involves capsaicin-sensitive nerve endings.

Unlabelled: The purpose of this study was to investigate the dentinogenesis of dental pulp tissue following transplantation and during regeneration in normal and germ free animals, as well as in vitro experiments.

Experiments: (1) Partial and complete exposure of dental pulp in germ free rats by removing the enamel and dentin of molars. (2) The central portion of rat incisor which consisted of pulp and pulp chamber were autografted into various tissues. (3) Explants of rat pulp tissue were cultured on dentin matrix. (4) Resin bonding agent, 4-META/MMA-TBB-O (Superbond), was placed directly on surgically-exposed dental pulp.

Results: (1) Dentin bridge formation was recognized at 5 days after operation in germ free rat. (2) The cut surface of the transplant exhibited dentin bridge at 7 days after implantation, and the thickness of the newly formed dentin increased gradually thereafter up to 30 days. (3) Cultured pulp cells had high alkaline phosphatase activity and bone- or dentin-like hard tissue was synthesized on the dentin matrix in vitro. (4) Dentin bridge formation was evident on the surgically-exposed dental pulp even after application of Superbond. From these results, it is suggested that pulp tissue has a high activity of dentinogenesis both in vivo and in vitro and 3 days is enough for pulp cells to express the odontoblast phenotype when inflammatory factors are not present.

Several inflammatory mediators including serotonin (5-HT) have been indicated to play a role in the sensitization of intradental nerves. In the present investigation, using the single fibre recording technique, the effect of locally applied 5-HT (1 mg/ml) and calcitonin gene-related peptide (rat CGRP 2 micrograms/microliters) on the function of intradental nerves in the dog was studied. The effect of these substances on the pulpal blood flow was also investigated to check their effective diffusion into the dental pulp. 5-HT induced a low-frequency background firing in 11 out of 30 nerve fibres. The number of fibres responding to probing, air blast and osmotic stimulation was increased significantly after 5-HT application. Three fibres responded to cold stimulation after 5-HT application; no responses were induced before. After CGRP application, a continuous low-frequency firing was induced only in 1 fibre out of 11 and 1 fibre which before did not respond to osmotic stimulation gave responses to saturated glucose. The responses to probing and air blasts were qualitatively unchanged. Local application of either of the substances induced a change in pulpal blood flow. It is suggested that while 5-HT is able to sensitize intradental nerves to various hydrodynamic stimuli, CGRP seems to be less effective. Pulpal inflammation with the release of inflammatory mediators may significantly affect the degree of dentine sensitivity.

Traditional restorative dental treatment has many shortcomings and has not been shown to be an effective method for managing caries. In spite of this, many dentists continue to be powered by an aggressive restorative approach which, in the light of changing "rules" of operative dentistry, must now be seen as inappropriate and as a form of iatrogenesis. Many things have changed in recent years, including: the prevalence of caries; understanding of the science of the caries process; a fuller appreciation of the problems inherent in restoring teeth; cavity design; restorative materials; and the demands of patients. Dental practice needs to change very dramatically if iatrogenesis is truly to be reduced to a minimum and dentistry is to provide the sort of preventive-based care the modern consumer is increasingly realising makes most sense.

This paper describes changes in use of oral health services and oral health in Finnish adults. The figures are taken from the Mini-Finland study of people aged 30 years or over (1980), a study of the oral health of persons aged 35 to 64 years old in the Jämsä Health Centre region (1990), and a study on the oral health of people aged 65 or over in the Varkaus region (1990). In 1980 one-third of Finnish adults aged 30 years or over visited a dentist at least once every two years. In 1990, 41% of the population between 35 and 64 years old visited a dentist at least once every two years. Among those aged 65 or over, however, most subjects visited a dentist only if they had an acute dental problem. An oral health check-up was the reason given for their last dental visit by 25% of adults in 1980. The percentage was slightly greater in 1990. Regular use of oral health services was reflected in better oral health. Occurrence of dental caries correlated strongly with use of oral health services. In 1980 only 4% of Finnish adults had a healthy periodontium. There was no marked improvement in 1990 in periodontal health. The most radical positive development was observed in relation to degree of periodontal loss. Despite some positive development, the association between oral health and use of oral health services has remained unchanged. The results support encouragement of an oral health check-up at least once every two years.

This follow-up study was carried out to survey the utilization of dental services among university students, together with treatment modalities received during their six years of university studies. Initially 20-year-old students were followed during six years, starting from their first year at the University of Helsinki. Results of the questionnaire showed that during the previous 12 months 59% of the students had had a dental appointment, mostly on their own initiative. According to the patient register, 83% of the students, during their studies, had received dental care financially subsidized at the Finnish Student Health Service (FSHS) in Helsinki. During the six years of follow-up, the mean number of appointments was 9.3 per patient (SD 6.8). Female students made dental appointments relatively more often than did male students (p < 0.01). The main treatment modality was restorative care. Patients did not show up for 3.5% of all appointments reserved. One sixth of all visits were made by a group representing 5% of the study group. In conclusion, as the utilization of FSHS dental services was very common, and as restorative dentistry continues to be the main treatment modality among Finnish university students, prophylaxis of caries in systematic dental health care programmes at FSHS is of prime importance and thus has a good possibility to reach each student.

Odontogenesis is an example of developmental process whereby pluripotential embryonic ectodermal and ectomesenchymal cells give rise to specific, highly ordered, spatial arrangements of overtly differentiated tissues. This process implies the sequential and coordinated expression of several molecules of defined biological activities. The data presented here demonstrate the occurrence, in the embryonic mouse incisor, of a striking correspondence between gradients of mitoses, chondroitin 6-sulfate distribution, retinoic acid receptor gamma and cellular retinoic acid binding protein I transcripts. Although purely phenomenological, these observations provide an important guide to the design of experiments for understanding the mechanisms of pattern formation during tooth development.