histological study of the pulp responses underneath visible light cured temporary filling material, experimental test

Temporary restorative materials play an important role in protecting the tooth and reserving pulpal health[1]. The reaction of the pulp beneath such a restoration depends on the material ingredients or its sealing properties. This in vivo study was performed to demonstrate the effect of IRM, ZOE, Citadur and Clip temporary restorative materials on the dental pulp and bacterial invasion via the dentinal tubules. Five adult female dogs were used to prepare class V buccal cavities on the posterior teeth. Each segment was filled with a different type of provisional tested filling material. Then the dogs were sacrificed 2 months later. The teeth were grouped, labeled and prepared for histological evaluation. Statistical analysis was performed to compare pulpal responses below various tested restorative materials. Some randomly selected sections from each group were stained with Gram stain for visualization of bacteria. IRM showed the least pulpal reactions, 80% of the cases revealed grade I inflammatory responses. This was followed by ZOE showing only 20% grade I and 70% grade II inflammatory responses. Pulpal response to Citadur varied between grade Il [44%] and grade III [56%] while Clip showed 18% grade II, 46% grade III and 36% grade IV inflammatory reactions. Also, bacterial invasion was demonstrated below Citadur and Clip, which was associated with grades III and IV [unacceptable] that may be due to the observation period of the study

use of a dentin adhesive instead of enamel bonding agent to reduce the etching time of enamel in primary teeth

Forty exfoliated primary incisors were divided into four groups. In two groups, enamel bonding agent was applied after etching the enamel for either 60 or 120 seconds. In the other two groups, universal bonding agent was applied after etching for either 60 or 30 seconds. The shear bond strength was evaluated in the four groups. The use of the universal bonding agent after etching the enamel for 60 seconds showed the highest shear resin bond strength. This bond strength did not differ significantly from that obtained with etching for 120 seconds followed by the application of enamel bond. Also, there was no significant difference between etching for 60 or 120 seconds before using the enamel bonding agent. It could be concluded that etching the enamel for 60 seconds is adequate for primary teeth. Etching time could be reduced to 30 seconds when a dentin adhesive designed to bond to the inorganic component of the tooth is used for resin bonding