250 J. Dent. 1989; 17: 250-251

International Abstracts

Section Editor: W. R. E. Laird

Effects of tooth surface treatment with acid solutions containing metal chloride on the bond strength of a self-curing resin. Harashima I., Hirasawa T., Tomioka K. et a/. (1989) Jpn. J Dent Mater. 8. 29-35.

The use of aqueous solutions containing an acid and a metal chloride as a tooth surface pretreating agent was evaluated. Nineteen solutions containing 10 per cent acetic (AA), citric (CA), lactic (LA) or phosphoric acid (PA) and/or 0.1 1 M aluminium (Al), cupric (Cu) or ferric chloride (Fe) were prepared. The tensile bond strengths of the TBB-0 initiated MENTA resin to tooth surfaces treated with the respective aqueous solutions were measured. The amount of calcium dissolved by each of the solutions was determined.

The demineralization of the tooth surface was mainly dependent on the pH of the aqueous solutions. There was no specific relationship between the bond strength and amount of dissolved calcium. This suggests that a high bond strength can be obtained without appreciable demineralization. Pretreatment with the CA-G, CA-Fe or LA-Cu solution markedly enhanced the bond strengths to both enamel and dentine, although these solutions demineralized tooth surface less than the solutions containing 10 per cent PA (13 references) H. Hisamitsu

Valutazioni sull’efficacia di applicazioni topiche in vivo di preparazioni a base di fluoro e stronzio su denti umani. (In vivo evaluation of the effectiveness of topical fluoride and strontium based applications in human dental enamel.) (1989) Minerva Stomatol. 38, 335-339.

This study evaluated in vivo the effect of topical application of fluoride and strontium on dental enamel. Thirty subjects were randomly divided into two groups, all of whom had to have their first upper premolars extracted. One of the premolars to be extracted was treated with three applications of APF gel (0.33 per cent NaF) in the first group and with a series of six topical applications of strontium chloride at 0.2 per cent and EDTA at 10 per cent in the second group. A significant increase was seen in the concentration of trace elements in enamel of treated teeth. The fluoride concentration was 0.23 and 0.05 &pm respectively in the most superficial and in the deepest of the observed strata and the strontium concentration was 0.07 &pm on average. In the control teeth the average concentrations of fluoride resulted in 0.08 &pm on the surface and in depth, while the strontium showed an average concentration of 0.03 pg/

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pm. Similar behaviour was observed for the depth of acid etching resulting in an average of 6.8 pm in the two groups of treated samples and of 1 I.4 and 9.7 Frn for the controls, respectively. The results indicate the usefulness of topical fluoride and strontium applications. (17 references) Mario Pezzoli

Durability of composite resins in accelerated boiling water immersion. Fujishima A., Miyazaki T., Takatama, M. et al. (1989) Jpn. J. Dent Mater. 7. 807-816.

To accelerate the degradation in water of composite resins, samples were stored in boiling water in a pressure cooker for a week and subjected to a tensile test measurement of surface roughness and SEM observation.

Samples stored in distilled water at 37°C for 1 week showed decreased tensile strength and a lowered equilibrium in Young’s modulus, and an increase of surface roughness. SEM photographs of the fractured surface showed evidence of separation of the filler from matrix resin.

The chemical degradation was considered to have been accelerated by storing samples in boiling water The durability of composite resins could be evaluated more rapidly by direct tensile test of samples stored in this condition. (24 references) H. Hisamitsu

Studies of the masticatory efficiency and muscle force of temporal and masseter muscles in full denture wearers bv liaht absorotion method. Ye Xiu-fen et al. (19887 Chin. J Stomatol. 23, (6). 334-336.

Changes in the masticatory efficiency and muscle force of temporal and masseter muscles in full denture wearers were studied using a light absorption, electromyography and computer EMG processing system.

At the beginning of wearing the full dentures, the masticatory efficiency of normal adults for the first week was 32 per cent, for the second week 38 per cent, for the first month 49 per cent, for the third month 51 per cent, for the sixth month 62.5 per cent and for the first year 8 1 per cent. The muscle force increased slowly over 3 months and increased significantly after 3 months. The muscle force and masticator-y efficiency gradually increased and presented a positive correlation. (8 references) Wei Yi and Liao Fang Gang