Monkey pulp reactions to restorative materials.

Deep buccal cavities in 99 teeth in eight young monkeys were filled with the following combination of materials: a light-cured microfilled composite with or without a base, a chemically cured composite with a base, a silicate cement, and a zinc oxide-eugenol cement. The acid etch technique and intermediate layer of resin was used in the composite group. Pulp reactions and presence and location of bacteria were studied after 8 days and after 90 days. In the short observation period the inflammatory reactions were more pronounced when unlined composite fillings were evaluated compared with silicate cement fillings and with lined fillings. Bacteria were seen in all unlined cavities and a significant association between presence of bacteria and moderate to severe inflammatory responses was found. The most severe inflammatory reactions were seen when bacteria were found in the dentinal tubules. After 90 days slight inflammatory changes prevailed in all groups. A significant correlation between bacteria and inflammatory reactions could still be observed.

In vivo abrasion of Profile and Adaptic composite resins.

Thirty-six Class I cavities in mandibular molars from 18 schoolchildren were filled with Profile or Adaptic using the acid etch technique. Impressions were taken at 6-month intervals and abrasion was recorded by measuring the increasing height of the exposed cavity walls on cast models. The mean abrasion for Adaptic was 61.4 micron per yr and for Profile 28.7 microns per yr.

Porosity of restorative resins.

Polyethylene tubes were filled with different types of composite resins using either the bulk-packing technique or the syringe injection technique. The porosity of the specimens was studied. Specimens made by light-activated systems were less porous compared to specimens made by two-paste systems. Use of the injection technique was followed by a reduction in porosity in both groups compared to use of the bulk-packing technique.

Capping of monkey pulps with Dycal and a Ca-eugenol cement.

Capping of 120 teeth in four monkeys was performed with Dycal or with a calcium-eugenol cement. The observation periods were 8 days or 90 days. The monkeys were killed, and the teeth were examined histologically. After 8 days, the pulp-tissue reactions were basically the same in the two groups. The tissue adjacent to the exposure site was characterized by varying amounts of necrotic tissue, inflammatory cells, and extravasated erythrocytes. Capping material and dentin chips were displaced into the pulp tissue. Particles from the capping materials were found in vessels, macrophages, and foreign body cells. After 90 days, more hard-tissue formation occurred in the Dycal group than in the Ca-eugenol cement group. The hard tissue was formed by either fibroblasts or the original odontoblasts.

A model for experimental endodontics by transplanting human dental roots subcutaneously to rats.

In 35 roots from extracted human teeth the pulp tissue was removed and the specimens autoclaved before being transplanted subcutaneously to rats. The animals were sacrificed 7, 14, 21, 90 and 140 d after transplantation and the skin and subcutaneous tissue containing the transplants were prepared for histologic examination. The human roots were well tolerated by the rats with a fibrillar connective tissue capsule surrounding the specimens. In the 90-d and 14-d groups a few root surfaces exhibited small resorption lacunae. The empty root canals became slowly occupied by a maturing granulation tissue occasionally containing foci of lymphocytes. After 140 d the canal tissue was still highly vascular with multinuclear giant cells occasionally located along the dentin walls but no internal resorption was recorded. It is concluded that this model may be useful for systematic testing of root filling materials concomitant with human studies.

Abrasion of class 1 restorative resins.

Studies have been made on the abrasion by food of different restorative resins in standard Class 1 cavities in mandibular first molars of schoolchildren. The abrasion was recorded by measuring the increasing height of the exposed cavity walls. It was found that Sevriton Simplified was abraded more than Adaptic, that no difference in abrasion between Adaptic and Adaptic without filler could be demonstrated, and that Adaptic was abraded more than an experimental composite containing 30% by weight Aerosil, an ultra-fine SiO2 filler with a grain size of the order of 25-50 nm. The results are in accord with the findings in an initial study by one of the present authors, in which the fillings were placed in denture porcelain teeth. It is stressed that the conclusions of the present work are pertinent only to the type of abrasion studied, i.e. chewing of food without the possibility of direct contact between the fillings involved and the corresponding antagonists.

Tissue formation in the root canal after total pulpectomy and partial root filling.

In twenty human teeth, total removal of the pulp was attempted, and the root canal was filled 2 to 4 mm. short of the foramen in the same sitting. The root filling consisted of gutta-percha points and Kloroperka N-ö as a sealer. The teeth were extracted after observation periods of 2, 6, and 10 months and committed to histologic examination. Microscopic evaluation demonstrated that after 2 months, the space in the canal between the root filling and the foramen was occupied by connective tissue slightly inflamed in the area adjacent to the root filling. After 6 and 10 months the entire space contained a fully developed cell-rich fibrous tissue, and only a few lymphocytes were observed adjacent to the root filling material.