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The very large chemical shift range provided by cobalt-59 yields well resolved lines for each of the nineteen isotopic species in the series of complexes ranging from Co(NH 3 ) 3+ 6 to Co(ND 3 ) 3+ 6 and each of the thirteen isotopic species in the similar series of tris(ethylenediamine)cobalt(III) complexes. The relative intensily distribution of these n.m.r. signals at equilibrium is related directly to the proton isotope composition of the solvent. This n.m.r. method of quantifying the isotope composition is examined with respect to the equilibrium isotope and the application to determination in aquerous and non-aqueous solvents.

In five young sibling New Zealand white rabbits the muscular complex on the lingual side of the midline of the mandible was severed and a V-shaped piece of bone with the midline muscular attachments was removed from the lower border. In five control rabbits an incision was made down to the lower border but there was no further operative interference. There was no appreciable difference in weight gain between the two groups over a period of 8 weeks. All animals had difficulty in “swallowing” for 2 weeks, and two of the experimental animals gave evidence of such difficulty at 8 weeks. Firm muscular reattachments in the midline of the mandible had occurred in all the experimental animals when examined at the end of the eighth week.

The use of intravenous metoprolol in a dose of 0.06--0.17 mg/kg body weight proved effective in the treatment of sinus tachycardia in excess of 150 beats/min and/or ventricular dysrhythmias associated with light halothane anaesthesia for outpatient dental surgery. There were no side-effects related to this cardioselective beta-blocker in the dosage used. The prophylactic use of oral metoprolol should be considered for patients who find the prospect of dental treatment a fearsome experience.

The paper takes the form of a discourse on the problems which face a dental adviser to a national government. Consideration is given to the type of person best suited to undertake the duties of such an adviser. A choice of two solutions is offered to solve the dental needs of a country. A scheme is presented which concentrates on the prevention of dental disease, and an alternative plan is outlined in which treatment of established disease takes priority.

Summary A case of calcifying odontogenic cyst associated with an unerupted maxillary canine tooth has been described.