• Monsiri Nardkosa D.D.S.
• Varisara Sirimaharaj D.D.S., Grad.Dip.Clin.Dent., M.D.Sc., Ph.D.
• Sitthichai Wanachantararak D.D.S., Ph.D.

Background: Only a limited number of reports existed about fluid flow through dentin in primary
teeth, none of them were studied in carious dentin in vivo.

Objectives: To study the dentinal fluid flow on both etched and unetched dentin surfaces beneath
carious lesions of vital primary mandibular and second molars by using impression and replica
technique.

Materials and Methods: Thirty primary lower second molars were included in this study. They were
divided into 3 groups according to the depth of the carious lesions. The teeth were anesthetized with
3% plain mepivacaine. Caries was removed with standard procedure. A silicone impression material
was then used to record the floor of the cavities before and after acid etching. Replicas were made by
casting the impressions with epoxy resin and examined under scanning electron microscope.

Results: Fluid droplets, round and ovoid in shape, were discovered on the replica of un-etched dentin
surfaces while porous surfaces were shown on etched dentin surfaces. One-way ANOVA statistical
analysis showed significant differences in the diameters of dentinal tubules, the numbers of dentinal
tubules/mm2 among the 3 different cavity depths in the etched groups, the diameter of fluid droplets
and the numbers of fluid droplets among the 3 cavity depths in the un-etched groups.

Conclusions: Fluid droplets were found on the replicas of un-etched dentin surfaces while the
openings of dentinal tubules were found on the replicas of etched dentin surfaces. Both fluid droplets
and dentinal tubules increased in diameters when cavity depth increased.

(CU Dent J. 2015;38:221-228)