Related Experiment Video
Updated: May 20, 2026
Microhardness Measurements on Tooth and Alveolar Bone in Rodent Oral Disease Models
Published on: April 26, 2024
Microhardness recovery of demineralized enamel after treatment with fluoride gel or CPP-ACP paste applied topically
Chris S Ivanoff1, Timothy L Hottel, Franklin Garcia-Godoy
1Department of Bioscience Research, College of Dentistry, University of Tennessee Health Science Center, 875 Union Avenue, Memphis, TN 38163, USA. civanoff@uthsc.edu
Purpose:
To evaluate the microhardness of demineralized enamel remineralized in saliva after applying 1.23% APF gel or CCP-ACP paste with dielectrophoresis (DEP) or diffusion for 3 minutes.
Methods:
In this laboratory study, 25 enamel blocks of bovine incisors were soaked in demineralizing solution (10 mM HCl pH 2.5) for 10 minutes and remineralized in saliva for 1 hour, after applying 1.23% APF gel or CPP-ACP paste without fluoride with dielectrophoresis or conventional topical application for 3 minutes. The mean and percentage changes of surface microhardness in pre-demineralization, post-demineralization and remineralization stages were measured in the five groups. The results of all five groups during the three stages were compared by ANOVA and paired t-tests (P = 0.05).
Results:
The average surface microhardness recovery of APF gel (12,300 ppm fluoride) applied with DEP was higher than APF gel applied topically, or CPP-ACP paste applied with DEP or topically, and water control (P < 0.05). The percentage of surface microhardness recovery for APF+DEP, APF+Diffusion, CPP-ACP+DEP, CPP-ACP+Diffusion, and water control were 88.17%, 13.62%, 7.14%, 5.45%, and 4.02%, respectively. Demineralization treatment decreased the surface microhardness of enamel in all groups and the surface microhardness recovery in the APF+DEP group was significant (P < 0.001). The only significant paired difference was between APF+DEP and all other groups. No other paired difference approached significance. Surface microhardness recovery of enamel with APF+DEP was 12 times or 1,200% greater than APF gel applied topically, and CPP-ACP paste either applied topically or with DEP in one 3-minute application.
