Ion release by endodontic grade glass-ionomer cement.

Cylindrical specimens (6 mm high x 4 mm diameter) of the endodontic grade glass-ionomer (Ketac Endo) were exposed to various media for 1 week, after which changes in their mass, pH of storage medium, and ion release were determined. In water, this cement was shown to release reasonable amounts of sodium, aluminium and silicon, together with smaller amounts of calcium and phosphorus, as well as taking up 2.41% by mass of water. A comparison with the restorative grade materials (Ketac Molar, ex 3M ESPE and Fuji IX, ex GC) showed both ion release and water uptake to be greater. All three cements shifted pH from 7 to around 6 with no significant differences between them. Other storage media were found to alter the pattern of ion release. Lactic acid caused an increase, whereas both saturated calcium hydroxide and 0.6% sodium hypochlorite, caused decreases. This suppression of ion-release may be significant clinically. Aluminium is the most potentially hazardous of the ions involved but amounts released were low compared with levels previously reported to show biological damage.

Shear bond strengths of glass-ionomer cements to sound and to prepared carious dentine.

The aim of this study was determine whether bonding of glass-ionomer cements to non-carious dentine differed from that to carious dentine. Five commercial cements were used, namely Fuji IX GP, Fuji IX capsulated, Fuji IX Fast capsulated (all GC, Japan), Ketac-Molar and Ketac-Molar Aplicap (both 3M-ESPE, Germany). Following conditioning of the substrate with 10% poly (acrylic acid) for 10 s, sets of 10 samples of the cements were bonded to prepared teeth that had been removed for orthodontic reasons. The teeth used had either sound dentine or sclerotic dentine. Shear bond strengths were determined following 24 h storage. For the auto-mixed cements, shear bond strength to sound dentine was found not to differ statistically from shear bond strength to sclerotic dentine whereas for hand-mixed cements, shear bond to sound dentine was found to be higher than to carious dentine (to at least p < 0.05). This shows that the chemical effects arising from interactions of glass-ionomer cements with the mineral phase of the tooth are the most important in developing strong bonds, at least in the shorter term.

[Evaluation of oral health in bulimia nervosa]. / Ocena stanu narzadu zucia w bulimii.

AIM: The aim of the study was to evaluate the dental status of bulimics with self inducing vomiting. METHOD: 33 bulimic female patients aged between 17 to 20, who were in need of hospitalization in the Department of Psychiatry, Poznan University of Medical Sciences, were compared to 31 age and sex matched healthy controls aged between 18 to 36. For each subject dental examination including calculation of caries, erosion and oral hygiene indexes: PlI, OHI-S, DMFT and TWI was performed. In both groups salivary flow and pH of the whole saliva were measured. RESULTS: Bulimics manifest a significantly higher retention of dental plaque and also higher frequency of enamel erosion, which were not present in the control group. Additionally, bulimics had more intense caries. Stimulated and resting salivary flow were poor, although they had the lowest pH values but were within the normal range. CONCLUSION: Patients with bulimia nervosa showed a higher number and severity of enamel erosion. There is also the high difference in amount of dental plaque, caries and changes in salivary secretion. These results highlight a need for close cooperation between the dentist and the patient's physician, which will then improve the diagnosis and treatment of this disease.

Ion-release, dissolution and buffering by zinc phosphate dental cements.

The interaction of zinc phosphate dental cement with aqueous solutions has been studied in order to elucidate the relationship between pH change and ion release (dissolution). For each storage medium (deionized water, lactic acid at pH 2.7 and lactate buffer at pH 2.2) five cylindrical specimens of zinc phosphate cement (6 mm diameter x 12 mm height) were prepared and weighed. They were stored individually in 8 cm(3) of solution for a week, then the pH was determined and the specimens reweighed. The solutions were replaced and the specimens stored for a further week, then the pH and the weight were again measured. This was repeated for four weeks. For each storage solution at each time interval, the concentration of ions leached (Na, Mg, Al, Zn and P) were determined using ICP-OES. The lactate buffer was particularly erosive and reduced specimens to 4.1% (+/-0.9%) of their original mass after 4 weeks. The lactic acid was also erosive, but in water, specimens showed no significant mass change after 4 weeks. In all media, Na, Al, Mg, Zn and P ions were released, with mole ratios varying at each time interval. In all cases, the pH shifted towards neutral, but the relationship between ion release and solution pH was not straightforward. From the mole ratios of ions, estimates could be made of the relative proportions of attack at matrix to attack at filler, and this showed attack at filler predominated in most solutions at most time intervals.

Buffering and ion-release by a glass-ionomer cement under near-neutral and acidic conditions.

Specimens of an experimental glass-ionomer cement were stored in water (initial pH 5.9) and aqueous lactic acid (initial pH 2.7) for storage periods of 1 week up to 6 weeks. Change in mass, solution pH and fluoride release were measured at weekly intervals, and other ions were determined at weeks 1, 2, 4 and 6. In water, cements raised the pH consistently to 6.7-6.9 from weeks 2 to 6, but this did not correspond to uniform amounts of ions released, nor even to consistent mole ratios of ions in solution. Similarly, in lactic acid, pH was raised to between 3.6 and 4.5, but without a consistent concentration of ions in solution. In near neutral conditions, calcium was found to be virtually insoluble and remained within the cement, whereas reasonable amounts of sodium, aluminium, phosphorus, silicon and fluoride were released at all time intervals, with downward trends over time. In acidic conditions, considerable amounts of calcium were released over time, and amounts of calcium, aluminium, phosphorus and silicon increased with time, reaching a maximum in week 4. This suggests that as maturation proceeds, there is an increase in the acid-soluble fraction of the cement containing these elements. Fluoride release was found to be as previously reported, i.e. greater amounts in the early stages of the experiment, and with a gradual decline, and with greater amounts in acid than in water. Determination of fluoride with and without the decomplexing reagent TISAB showed that 70-75% of the total fluoride was released in "free" form in water for most weeks, whereas in acid, it declined sharply and by week 6, an estimated total of 96% of the fluoride released was complexed.

Are Polish and Swedish dental graduates adequately prepared for dental practice in the UK? A discussion of the transferability of general dental practitioners in Europe.

In the context of European Union harmonization, this article compares the systems of training for general dental practice in three European countries, the UK, Sweden and Poland. A UK perspective is adopted and the question as to whether dentists who have qualified in Poland or Sweden are adequately prepared for practice in the UK is explored. The paper is a result of discussion between providers of dental training in the three study countries. Key similarities, strengths and weaknesses are identified and issues pertinent to the transferability of general dental practitioners within Europe are raised.