Dental erosion in deciduous teeth--an in vivo and in vitro study.

OBJECTIVE: The aims of this study were to report on severe dental erosion and its associated etiological factors in deciduous teeth of Saudi children (n=16, X macro=6.5 years, R=5--8) in vivo, and to confirm (or reject) the clinical diagnosis by scanning electron microscopy (SEM). Another aim was to study progression of erosion in vitro using extracted healthy deciduous and permanent teeth. METHOD: For the in vivo study, a questionnaire and clinical examination was completed, medical history obtained and exfoliated eroded teeth (n=8) examined by SEM. For the in vitro study, enamel specimens were prepared from Saudi (n=21) and Finnish (n=19) deciduous teeth as well as Finnish permanent teeth (n=20), immersed in 2% citric acid for 5--30 min, microhardness measurements performed, and the specimens studied by SEM. RESULTS: The in vivo investigation showed that high intake of acidic drinks and fruits, upper respiratory tract problems and frequent medications may constitute possible etiological and/or aggravating factors for severe dental erosion in Saudi children. Deciduous tooth enamel was softer than permanent tooth enamel. SEM showed no clear differences in the ultrastructure of the enamel specimens amongst the three groups. The clinical diagnosis of severe dental erosion in those cases studied was reliable as verified by SEM. CONCLUSIONS: The presence of dental erosion in children is likely to be associated with a number of general health and dietary factors but is also aggravated by the relatively more rapid progression of erosion in the deciduous teeth.

Hospital mouth-cleaning aids may cause dental erosion.

Maintaining satisfactory oral health in bed-ridden patients often calls for special aids, such as moistened cotton swabs. The purpose of this in vitro study was to investigate three commercially available swabsticks meant for hospital use (Dentiswab, Lemon-Glycerin Swabsticks, and Lemon Glycerine Swabs), and one saliva-stimulant chewing tablet (Cassisal), regarding their possible erosive effects on dental enamel. A bovine enamel model system was used. Specimens were incubated for 4 hours in the test solutions made of the products. The results showed statistically significant enamel softening caused by two of the cotton swabs (Lemon-Glycerin Swabsticks and Lemon Glycerine Swabs). Incubation in the solutions made of Dentiswab cotton swabs and Cassisal tablets caused only minimal changes in microhardness. Profilometric measurements supported these results. Stereomicroscopy and SEM showed distinct erosion in specimens treated with the lemon swab solution, while the other two did not cause erosion. Thus, attention should be focused on choosing the less erosive products if special mouth-cleaning aids are used.

Surface ultrastructure of rat molar teeth after experimentally induced erosion and attrition.

Young Osborne-Mendel rats were given different diets for 6 weeks. Effects of soft and rough food as well as acidic sport drink on the lingual surfaces of first mandibular molars were studied. In addition, the effect of fluoride on erosion was examined. A Jeol JSM-35 scanning electron microscope was used to visualize tooth surface ultrastructure. Intact surfaces were found in the rats given soft food and distilled water. Sport drink (pH 3.2) caused severe erosion with total loss of supragingival enamel and exposure of dentin. Attrition effects were seen on the cuspal parts of the surface when rough food was given. Tooth tissue loss was greatest in the rats given rough food and sport drink; signs of both erosion and attrition could be seen. When fluoride was added to the sport drink erosion lesions were less severe and if dentin was exposed, the dentinal tubules were partly occluded. These SEM observations support earlier studies which have suggested that erosion may alter tooth surface so that it is more susceptible to attrition; in those lesions, however, clinical diagnosis of the initial causes may be difficult.

Efficacy of chlorhexidine solution with fluoride varnishing in preventing enamel softening by Streptococcus mutans in an artificial mouth.

For study of the enamel-protective effect of chlorhexidine-fluoride applications, the labial surfaces of pieces of bovine incisors were treated with 0.2% chlorhexidine gluconate solution, with Duraphat fluoride varnish, or with both of the above agents, while one group was treated with distilled water and one was left as an untreated control. Furthermore, a placebo varnish was used in the chlorhexidine- and distilled-water-treated groups; all the varnishes were removed after 24 h. The enamel slabs were mounted pairwise in an artificial mouth to form approximal contacts. The teeth were continuously rinsed with a common pool of artificial saliva to which was added 3% sucrose, and which was infected on the first day with Streptococcus mutans, "Ingbritt". The saliva was renewed daily and the incubation at 37 degrees C lasted for 10 days. The appreciable softening found in the distilled-water- and placebo-varnish-treated group tended to be prevented by the chlorhexidine and even more by the fluoride treatment, while the chlorhexidine-fluoride treatment prevented enamel softening completely. The saliva, infected only on the first day, and renewed daily, tended to become more acidified toward the end of the experimental period, obviously because the fermenting organisms had infected the surfaces of the model and formed plaque-like coatings on the enamel.

Effect of fluoride varnish and solution on enamel erosion in vitro.

The effect of fluoride varnish and solution on initial enamel erosion was studied. Enamel specimens prepared from human third molars were treated for 24 h with Duraphat varnish (2.26% F) or for 48 h with NaF solution (1.2% F), washed, and immersed in cola beverage (pH 2.6) for up to 15 min. The surface microhardness was measured using a Vickers diamond in a Leitz indentation apparatus at base-line, after fluoride treatment, and after 1, 5, and 15 min exposure to acidic drink. The specimens were then prepared and studied using a JEOL JSM-35 scanning electron microscope. The results showed that both fluoride treatment caused an increase in enamel hardness values and subsequent inhibition of softening which was statistically highly significant. Scanning electron micrographs revealed the difficulty of removing Duraphat varnish from the enamel surface, and remnants of varnish were seen irrespective of vigorous sonication in acetone. However, in areas devoid of varnish, erosion was observed as mainly irregular lesions similar to those seen in the NaF solution treated and control specimens. The present study showed that treatment of enamel with topical fluoride prior to acidic challenge can inhibit initial erosion.

Drinks and dental health.

The average daily requirement for water in man is 2-3 litres, of which more than half comes from drinks. Although the total consumption of various drinks is quite stable, the choices of beverages are slowly changing. In many Western countries e.g. the use of milk is declining while consumers drink greater amounts of soft drinks, including fruit juices and carbonated beverages. These changes may also affect dental health because of the potential risk of sugar and acid-containing drinks to cause dental caries and erosion. The effects of drinks in the human mouth are, however, strongly related to many individual factors and prediction of dental effects is therefore difficult. Anyway, there are risk patients who should be recognized, and risk products which should be noticed in product formulation. If attention is paid to such factors in the future harmful effects of drinks on teeth may be minimized.

Effects of various sport drink modifications on dental caries and erosion in rats with controlled eating and drinking pattern.

A sport drink mixture, pH 3.2, containing 6% sucrose, was given to Osborne-Mendel rats, either as such or supplemented with 15 ppm fluoride, 38.5 ppm magnesium or both. Distilled water was given to the control groups. The rats were fed either a slightly cariogenic, powdered food containing 15% sucrose, or commercial pellets. Food and drink were available ad libitum for 6 weeks. A feeding machine was used to facilitate control of eating and drinking pattern. Daily intake of powdered, sugar-containing food was significantly smaller than that of pellets and, on the other hand, sport drink was consumed significantly more than distilled water. However, an appropriate energy balance was achieved with all of the dietary combinations, and no significant differences in weight gains were found. Sport drink did not significantly promote caries but induced marked erosion on the lingual surfaces of the lower molar teeth. Addition of fluoride to the sport drink significantly reduced caries (caused by powdered food) and had preventive effect on erosion, while addition of magnesium had no clear effect on either caries or erosion. No significant intergroup differences were found in eating or drinking patterns due to fluoride or magnesium additions.

Effect of sport-drink with and without fluoride and magnesium supplements on rat performance.

Young Osborne-Mendel rats were given different diets ad libitum for 6 weeks. Food was either a purified powder with sucrose (15%) or commercial pellets, and drink was either distilled water or a sugar-containing (6%) sport-drink with or without added fluoride (F), magnesium (Mg) or both. Despite differences in the energy density of the diets, daily intakes were the same in terms of metabolisable energy and resulted in equal weight gains for all groups. Interscapular brown fat hypertrophied in response to powdered food, while both sugar-containing food and sport-drink were effective in accumulating white fat. When exposed to cold air at -20 degrees C for 2-4 h, most of the rats were able to maintain normothermia. Only the rats fed pelleted food and given distilled water were less resistant to cold than the others. After exposure to cold, the reserves of muscle glycogen were least in those rats having the poorest performance in the cold. In contrast, the stores of liver glycogen, plasma glucose and adrenal ascorbic acid were associated with pelleted food, rather than with the exposure to cold or type of drink. It is concluded that the presence of purified, simple sugars, either in food or drink, is the most likely explanation of the results obtained. The F and Mg supplements to the sport-drink did not modify the parameters measured.

Erosive effect of a sport drink mixture with and without addition of fluoride and magnesium on the molar teeth of rats.

A sport drink mixture (pH 3.2), either as such or supplemented with 15 ppm F or 38.5 ppm Mg or both, was given to Osborne-Mendel rats as the only liquid for 42 days. The erosion was scored on the lingual surfaces of the first mandibular molar teeth. Sport drink caused marked erosion, but in the groups where fluoride, alone or with magnesium, was added to the drink, the erosion damages were less severe. Magnesium alone had no clear effect on erosion. Dental plaque, induced by a powdered diet containing 15% sucrose, seemed to modify the erosion process by covering a part of the enamel and thus protecting these areas from the direct effect of acidic drink.

A semiquantitative method of recording experimental tooth erosion and estimating occlusal wear in the rat.

As the erosive agent, a sport-drink mixture with pH 3.2 was given to Osborne-Mendel rats for 6 weeks. Lingual surfaces of the right first mandibular molar crowns were chosen for the recording. With the aid of a drawing tube mounted on a stereomicroscope, enlarged drawings of the surfaces were made encircling the intact and eroded areas. A computer-coupled analyser was used to measure the areas of the total surface, intact surface, eroded enamel and exposed dentine in square millimetres. The data was evaluated statistically and used to calculate erosion changes and to estimate occlusal wear.

Effect of a sport drink mixture with and without addition of fluoride and magnesium on plaque formation, dental caries and general health of rats.

A sport drink mixture (pH 3.2) containing 6% sucrose was given to Osborne-Mendel rats for 42 days. In some experimental groups the drink was supplemented with 15 ppm F, 38.5 ppm Mg or both F and Mg. The rats were fed a slightly cariogenic powdered diet containing 15% sucrose. Sport drink mixture increased significantly the accumulation of plaque but, compared with a group that drank distilled water, did not affect caries. Addition of fluoride to the sport drink mixture, alone or with magnesium, significantly reduced caries and tended to decrease plaque; addition of magnesium had no clear effect on plaque or caries. In spite of the fact that the rats had a sport drink mixture as the only drink for 6 wk, there were no untoward effects on growth, in histological studies of the inner organs, or in Ca, Mg, Na and K contents of kidney, heart and aorta.

Bursal fabricii as a peripheral lymphoid organ. Transport of various materials from the anal lips to the bursal lymphoid follicles with reference to its immunological importance.

In tracer studies, various particulate and molecular materials applied on the anal lips of chickens were transported to the bursal lumen. From here some of the tracers were further transported into the bursal lymphoid follicles and colloidal carbon even to the bursal stroma. In immunization experiments, Brucella abortus organisms and SRBC were applied on the anal lips of 1-day-old, 4-week-old and 10-week-old chicks on 5 consecutive days. Although Brucella bacteria in tracer studies were not found in the bursal tissue, agglutinin response to Brucella was observed in the 4-week and 10-week groups as early as 3 days after the last application of this antigen. The response to SRBC was strong only in the oldest group of chickens. When stimulated continuously, the agglutinin titres reached their highest values after the 2nd week and then began to decrease to rather low levels. In the youngest age group, the anti-SRBC titres, however, remained low during the whole experimental period, and even in the 4-week group the anti-SRBC response was weak. Bursectomy, carried out at the age of 10 weeks, inhibited the agglutinin response to Brucella but affected only little the response to SRBC. It is concluded that by taking up antigens per anum the chicken possibly gains part of its basic immunity. In this immune response the bursa seems to play an important role at least with some antigens, and thus the bursa may have an immunofunction comparable with that found in peripheral lymphoid organs.