Gap measurement between composite fillings and cavity walls in three different cavities.

Adaptabilities of 8 kinds of resinous restorations on class 5, cervical, and root surface cavities were compared and examined. Human extracted premolars were used as experimental specimens. Restored specimens were divided into two groups: a short storage group stored for 2 weeks and a long storage group for 6 months. After thermal cycling had been undertaken with each group during storage, replicas on vertical section were made to be observed by SEM, the gaps of which were measured on the photographs. These following conclusions were obtained as a result: 1. The appearance and width of gaps between resin and cavity walls were characterized by kinds of cavities. 2. In the class 5 cavity gaps were observed on cavity floor, while almost no gaps were observed in other areas which shows fine adaptability. 3. In the cervical cavity gaps appeared in only cavity floor and on gingival wall. 4. In the root surface cavity the gaps were observed on all cavity walls, whose width was smaller on occlusal wall and especially wider on cavity floor. 5. Clearfil-F and Clearfil-FII showed fine adaptability on all cavities in general, especially on dentinal cavity wall. 6. Isopast without bonding agent and Pile-A as control showed wider gaps than the other adhesive resin. 7. Almost all the materials showed a tendency to form gaps which increased over the passage of time. The difference of width, however, varies depending on the materials; especially stable in Clearfil-F and Clearfil-FII their adhesive power showed no decrease during the experimental period.