Quantitative study of the proportion of the pore volume of human fluorotic enamel filled by resin infiltrant

- Data on enamel pore volume infiltrated by resin infiltrant is lacking.
- Loosely bound water volume (α2) is the volume available for resin infiltration.
- Infiltrant volume and α2 in fluorotic enamel were studied quantatively.
- Infiltrant volume ranged from 1.8 to 17.7% (mean of 10%) of the enamel pore volume.
- Infiltrant and α2 volumes correlated strongly but lacked good agreement.

AimCapillarity theory predicts that the pore volume infiltrated by a liquid in a body with tubular capillaries is directly proportional to the capillary radius. The expected volume available for infiltration is the loosely bound water volume, which can be related to the capillary radii. We tested the hypothesis that the proportion of the pore volume infiltrated by resin infiltrant (Vratioresin) is correlated and agrees with the proportion of the pore volume with loosely bound water (Vratioa2).DesignSeven human fluorotic third molars (4 unerupted and 3 erupted; TF scores 4 to 7; fluoride content of inner coronal dentin ranged from 143 to 934 μg Fluoride/g) were prepared and resin infiltration was performed during 10 min in fluorotic enamel ground sections. Penetration depths were measured (polarizing microscopy and CLSM) and mineral volume and non-mineral volumes were measured at histological points (n = 92) along transversal lines traced from the enamel surface to the enamel-dentin junction.ResultsNo well-mineralized surface layer was found. Infiltration depths ranged from 250 μm to 900 μm. Vratioresin ranged from 1.8 to 17.7% (mean of 10.13% ± 4.1%), was lower than Vratioa2 (p < 0.00001 Hedge's g = 1.51, 95% CI: 1.18/1.83), and correlated positively with Vratioa2 (R = 0.684; 95% CI: 0.557/0.780) and negatively with the air volume remained after infiltration (R = −0.79; 95% CI: −0.698/−0.780). Vratioa2 exceeded Vratioresin in 5% (1/4 of Vratioa2) on average.ConclusionVratioa2 and Vratioresin correlated well, but lacked good agreement. Organic matter, firmly bound water and air remained in enamel pores after resin infiltration.