826 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Figure 7. Constant-temperature bath with four dissolution units tenfold just prior to use. Prolonged storage of the 0.1M lactate buffer may result in mold growth. Conditioning o1' Mounts Each new tooth mount is conditioned in the dissolution apparatus with 40- ml po•ions of 0.1M plI 4.5 laetate buffer for 9, one-hour periods, with fresh buffer solution added after one hour of conditioning. hnmediately after each enamel solubility test, the individual mount should be conditioned for 9, one- hour periods. At the time when no further tests are contemplated on the same or successive days, the mounts are conditioned for 9, one-hour periods. Since there is the danger of effects h'om previous treatments, it is very important to condition the teeth properly before each test. Most mounts can be used for 10 individual tests before discarding. Enamel Solubility Test After proper pretest conditioning, the conditioned tooth •nount is etched in the dissolution apparatus with 40 ml, accurately measured, of 0.1M pH 4.5 lactate buffer for 15 rain at 37øC to determine the pretreatment solubility. A

THERAPEUTIC DENTIFRICES 827 reservoir of lactate buffer is maintained at 37øC for pre- and post-treatment use. The apparatus is disconnected the lactate etch solution is collected and saved for calcium and phosphate analyses. The mount, stirrer, and beaker are thoroughly rinsed with purified water, the rinse is discarded, and the apparat- us is reassembled. A 20-ml mixed slurry of 10 g of paste and 30 ml of purified water is added. The mount is treated for 5 •nin at 37øC with 20 ml of the uni- form 1:3 aqueous slurry of the paste (10 g of paste and 30 ml of purified water thoroughly mixed with flared plastic tipped stirring rod). The apparatus is then disconnected, the treatment mixture is discarded, and the mount is thoroughly rinsed with purified water to remove all traces of the treatment mixture. It is important that this rinsing step be thorough for traces of treatment paste will inhibit post-treatment etching. The apparatus is re- assembled and the pretreatment exposure of the mount is repeated, in exact detail, to 40 ml of O.1M pH 4.5 lactate buffer for 15 min at 37øC. The appa- ratus is disconnected the lactate etch solution is collected and saved for cal- cium and phosphate analyses. The mount, stirrer, and beaker are then thor- oughly rinsed with purified water. The rinse is discarded, the apparatus is reassembled, and the mount is conditioned with lactate buffer in order to prepare it for another enamel solubility test. The concentration of phosphate and calcium in the pre- and post-treatment lactate etch solutions are deter- mined using the Lucena-Conde molybdate method and atomic absorption spectrometry. The per cent enamel solubility reduction (ESR) is calculated as follows: A-B % ESR--- A A = mg of phosphate/calcium in pretreatment etch B = mg of phosphate/calcium in post-treatment etch SUMMARY The dentifrice formulation which helps clean teeth and refresh the mouth has been used to bring anticaries agents to the mouth. Laboratory tests can be used to assess the compatibility of the formulation with the agent and the availability of the agent to the teeth. Correlation of laboratory tests with the results of clinical studies of the same and comparable agents permits a more meaningful interpretation and extrapolation of laboratory data and may re- duee the future need for clinical studies. ( Received February 1, 1973) REFERENCES (1) Lundquist, C., Tooth mortality in Sweden, a statistical survey of tooth loss in the Swedish population, Acta Odontol. Scand., 25, 289-322 (November 1967).