Extracted monkey teeth were endodontically treated, stored in milk or saliva for two or six h, and then replanted. Periodontal conditions were evaluated after eight wk. Teeth that had been stored for two or six h in milk or for two h in saliva showed periodontal healing almost as good as that of immediately replanted teeth. Teeth that had been kept in saliva for six h or bench-dried for one h showed extensive replacement resorption. Milk may thus be recommended as a storage medium for ex-articulated teeth prior to replantation in cases when immediate replantation is not possible.

Dentoalveolar ankylosis (replacement resorption) is a serious complication after replantation of avulsed teeth. The purpose of the present study was to investigate the influence of masticatory stimulation on dentoalveolar ankylosis after replantation of avulsed teeth. Monkey upper incisors were extracted, air‐dried for 1 h, endodontically treated and replanted. No splinting was used. One group of monkeys was given hard pelleted food, while another group was given soft diet during a healing period of 8 wk. The periodontal conditions were evaluated histologically with a morphometrical method. The replanted teeth of the monkeys given the hard pelleted food had significantly less ankylosis and a larger area of the root surrounded by a normal periodontal membrane than the teeth from the monkeys given a soft diet. In conclusion, development of ankylosis seemed to be partially prevented or reduced by masticatory stimulation.

Root resorption of replanted teeth is dependent on the duration of the extra-alveolar period and on the storage environment. In the present investigation the significance of preserving the humidity of the periodontal ligament (PDL) during the extra-alveolar period was tested on isolated PDL cells and on replanted monkey teeth. The isolated PDL cells were tested with respect to cell viability (trypan blue exclusion test) and to cell recovery (number of cells after additional cultivation). About 70% of the cells were viable and 44% recovered after 1 h in a humid atmosphere. Practically no cells were viable or recovered after 1 h of drying. Replanted teeth that had been wrapped in plastic foil for 1 h before replantation showed no more resorption than immediately replanted teeth. This is in contrast to teeth dried in air for 1 h before replantation. They showed extensive root resorption on almost all root surfaces. Thus, prevention of evaporation of tissue fluid from the PDL must be considered a primary goal if the tooth cannot be replanted immediately.

A series of positron emission tomography scans was made on two monkeys during a 16-month period when they received manganese(IV)oxide by subcutaneous injection. The distribution of [11C]-nomifensine uptake, indicating dopamine terminals, was followed in both monkey brains. The brain distributions of [11C]-raclopride, demonstrating D2 dopamine receptors, and [11C]-L-dopa, as a marker of dopamine turnover, were followed in one monkey each. The monkeys developed signs of poisoning namely unsteady gait and hypoactivity. The [11C]-nomifensine uptake in the striatum was reduced with time and reached a 60% reduction after 16 months exposure. This supports the suggestion that dopaminergic nerve endings degenerate during manganese intoxication. The [11C]-L-dopa decarboxylation was not significantly altered indicating a sparing of [11C]-L-dopa decarboxylation during manganese poisoning. A transient decrease of [11C]-raclopride binding occurred but at the end of the study D2-receptor binding had returned to starting values. The magnetic resonance imaging (MRI) revealed that the manganese accumulated in the globus pallidus, putamen and caudate nucleus. There were also suggestions of gliosis/edema in the posterior limb of the internal capsule. MRI might be useful to follow manganese intoxication in humans as long as the scan is made within a few months of exposure to manganese, i.e. before a reversal of the manganese accumulation.