This scanning electron microscopic study evaluated the adaptation of two visible light-cured bases, Calcimol LC and Ionoseal, to the dentinal surface after the use of various techniques to insert the resin composite material. Twenty-eight Class I cavities were prepared and restored in four groups: seven Calcimol LC and resin composite placed with a bulk or an incremental technique; and Ionoseal and resin composite placed with a bulk or an incremental technique. The specimens were sectioned longitudinally through the center of the restoration and an impression was made with a poly(vinyl siloxane) impression material. When the tooth surfaces and the impressions made from these surfaces were compared in the scanning electron microscope, extra gaps on tooth surfaces were observed that were not apparent in the impressions. These extra gaps probably resulted from desiccation of tissues; thus, the observation of replicas was useful to eliminate the inclusion of "false" gaps in the analysis. The results indicated that there was no substantial difference between Calcimol LC and Ionoseal base materials placed under resin composite inserted with an incremental technique.