EVALUATION OF DENTAL ABRASIVES 167 to consider that others factors, such as particle hardness, shape, and distribution, can also affect the abrasiveness of the raw materials. ACKNOWLEDGMENTS We acknowledge Colgate Palmolive Ltd. for supplying the raw materials the Monsanto Company for supplying calcium pyrophosphate reference material the Dentistry School and Faculty of Pharmaceutical Sciences of Ribeirgo Preto, University of Sgo Paulo, for tooth samples Dr. J.J. Hefferren from Kansas State University for advice and CNPq and FAPESP for financial support for this project. REFERENCES (1) W. E. P. Roa, Aplicagio e composigio de dentifrfcios, Aerosol Cosmet., 5, 5-14 (1983). (2) H. Panzeri, Personal communication (Dentistry School of Ribeirio Preto, SP, Brazil, 2001). (3) R. Boer, A. S. H. Duinkerke, and J. Arends, Influence of tooth paste particle size and tooth brush stiffness on dentine abrasion in vitro, Caries Res., 19, 232-239 (1985). (4) S. Kinoshita, T. Arai, and R. Uraguchi, Abrasive properties of commonly ua_d dentifrices, Bull. Tokyo Med. Dent. Univ., 26, 225-242 (1979). (5) H. Panzeri, E. H. G. Lara, F. Siessere, and R. M. Marchetti, Availagio de dentifrfcios. 2 a parte: Forma a distribuigio de partfculas abrasivas, Odontd/ogo Moderno, VI, 13-25 (1979). (6) J.j. Hefferren, A laboratory method for assessment of dentifrice abrasivity,J. Dent. Res., 55,563-573 (1976). (7) M. G. Navarre, The Chemistry and Manuj•kcture of Cosmetics (Continental Press, Orlando, Florida, 1975), Vol. III, pp. 445-470.

j. Cosmet. Sci., 52, 169-184 (May/June 2001) Secondary ion mass spectrometric investigation of penetration of coconut and mineral oils into human hair fibers: Relevance to hair damage S. B. RUETSCH, Y. K. KAMATH, AARTI S. RELE and R. B. MOHILE, TRI/Princeton, Princeton, NJ 08540 (S.B.R., Y.K.K.), and Marico Industries Ltd., Andheri, Mumbai 400 058, India (A.S.R., R.B.M.). Accepted for publication March 15, 2001. Synopsis An attempt has been made to show the difference in the penetrability of coconut oil and mineral oil in human hair. We have used secondary ion mass spectrometry (SIMS) in combination with a time-of-flight (TOF) mass spectrometer. Characteristic ions formed by the pure components when bombarded with gallium ions have been identified with their m/z values. The distribution of the ion, characteristic of the particular treatment, has been established in the cross sections of hair treated with coconut and mineral oils. The results show that coconut oil penetrates the hair shaft while mineral oil does not. The difference may be due to the polarity of the coconut oil compared to the nonpolar nature of the mineral oil. The affinity of the penerrant to the protein seems to be the cause for this difference in their behavior. This study also indicates that the swelling of hair is limited by the presence oil. Since the process of swelling and deswelling of hair is one of the causes of hair damage by hygral fatigue, coconut oil, which is a better penetrant than mineral oil, may provide better protection from damage by hygral fatigue. INTRODUCTION In an earlier study (1) the beneficial effect of coconut oil used as a pre-wash conditioner was investigated. Use of coconut oil was found to significantly reduce cuticular damage during combing. This was attributed to the hydrophobicity of the oil, which reduced the swelling of the cuticle that otherwise would have damaged the scale structure, especially in wet grooming. The lubricating effect of the oil further contributed to the reduction in damage. In Asian and African countries, vegetable oils are extensively used as hair dressings, and are known to reduce hair damage. Anecdotal accounts also suggest that the beneficial effects of oils accrue from the penetration of oils into hair and skin. Although conven- tional concepts of diffusion doubt the penetration of high-molecular-weight compounds such as polymeric conditioners (above a molecular weight of-1000) beyond the cuticu- lar sheath, claims have been made (2) to the contrary. However, in the case of coconut 169