No abstract

Dense (97-99.9%) hydroxylapatite ceramics were implanted in muscle and bone tissue of rats. The aim of this study was to compare apatite implant material made of commercially available powder with laboratory powder prepared in a painstaking manner. Biocompatibility, biostability, and adherence to bone were evaluated. In muscle tissue the implants were found to be encapsulated with a very thin connective tissue layer. Implantation in excavated bone tissue resulted with new bone directly deposited against the implant surface, irrespective of the type of hydroxylapatite used. When the implants were protruding from the bone surface, bone appeared to grow up to the edge of the protruding part of the implant. A very strong bonding developed; push-out tests indicated that the bone fractured but never at the interface. Histologic studies proved that a sleeve of newly formed bone closely encased the implant, regardless of shape. It was concluded that dense apatite ceramics are fully compatible with the tibia of the rat and that no degradation of the implant material occurred for intervals of up to 6 months after implantation. The very strong bonding without mechanical retention indicated continuity between artificial hydroxylapatite and natural bone. No difference was found between the biological behavior of the hydroxylapatites prepared from commercial or laboratory starting powders.

No abstract

No abstract

It is concluded that, although a reduction in dental anxiety level was present, a relatively large proportion of patients did not improve, in terms of both dental anxiety and dental attendance.

No abstract

Infusion of propofol by a target-controlled infusion (TCI) system is effective in achieving conscious sedation for anxious patients presenting for dental surgery. It is a common clinical observation that anxious patients require more anaesthetic drugs than non-anxious individuals. In study 1 we have defined blood propofol concentrations necessary for conscious sedation in both anxious (n = 23) and non-anxious (n = 18) patients. The pump performance of the TCI system, using Gepts' pharmacokinetic model, was evaluated in these two patient groups. Subsequently, clearance of propofol was compared in the two groups. Mean measured venous serum propofol concentrations obtained between 20 and 35 min after the optimal sedation level was reached were 1.6 (SD 0.2) micrograms ml-1 in the anxious patients compared with 1.7 (0.3) micrograms ml-1 in the control group (study 1) and 1.4 (0.27) micrograms ml-1 in study 2. The pump systematically overpredicted measured propofol concentrations in both groups (study 1). There was no significant difference in propofol clearance between the two groups. In study 2, an optimized set of microconstants was derived which should more accurately predict the pharmacokinetic profile of the anxious population and this set was tested prospectively in another group of 12 anxious dental patients. Bias and precision with the optimized kinetic set were significantly less than the values obtained in study 1. We conclude that there was no significant pharmacokinetic differences between anxious and non-anxious subjects receiving subanaesthetic doses of propofol for conscious sedation.

In order to investigate the relationship between dental anxiety and some personality traits, a group of 103 patients suffering extreme dental anxiety and therefore enrolled in a special treatment program were compared with controls sampled at random. The mean scores of the controls on dental anxiety measurements and on questionnaires dealing with personality traits were transformed into 50 with standard deviation equal to 10 to make them mutually comparable, and these subsequently were used as reference points, from which the likewise transformed mean scores of the anxiety group have to differ substantially if both groups stem from different populations. The mean scores were tested for difference with ANOVA. It appears that the anxious patients are more neurotic, i.e. more unstable, than the controls. Moreover, the patients feel themselves more uncertain with regard to having control, are less decisive, have a lower self-esteem, are less inclined to act and are, in general, anxious persons. These findings may have implications for selecting the most appropriate approach for amelioration of their anxiety or support of their coping capacity.