Influence of Surface Deposits on Diffusion of Self-Assembling-Peptide (P₁₁-4)

Objectives: Successful treatment of initial caries with self-assembling-peptides (Curodont-Repair™) depends on penetration of P₁₁-4 monomers into subsurface lesion where monomers form 3D-scaffolds with high affinity for calcium and phosphate. The presence of biologically complex-layers (plaque, mineral-deposits) on tooth surface may influence penetration. This study investigated the effect of deposits on diffusion of P₁₁-4 into initial enamel lesions.
Methods: Five human molars were selected and sectioned into 4 sections. White-spot lesions were created in all specimens using 5-days pH-cycling–protocol. Each tooth section was randomly assigned to one of four treatment groups; control received no treatment (CON), and three experimental groups treated for 5 min with slurry of their respective toothpaste, standard 1100-ppm (STP), 5000-ppm prescription (Rx), 7% Hydroxyapatite (HA). Scanning Electron microscopy (SEM) was used to assess deposition of mineral on tooth surface. Using confocal laser fluorescence microscopy (CLFM), mean depth of penetration (DP) of fluorescence-labelled P₁₁-4 when signal disappeared was determined for each group at 5 and 10min penetration-times (PT). Using ANOVA, followed by Tukey’s multiple comparison, mean DP was compared between CON and each group at the two PT. Mean DP was compared within same group at each PT.
Results: SEM revealed CaF₂-deposits on enamel surface of all treated-groups but not on Control. HA and Rx groups showed more dense granular structure. CFLM-captured images of Rx- and HP-treated lesions demonstrated less total/average fluorescence compared to STP and CON. For 5min PT, mean DP was significantly (P<0.05) greater in CON (710±20.1μm) compared to STP (415.8±5.9μm), Rx (411.8±7.3μm) or HA (412.11±6.2μm). DP did not differ among the test-groups. Similar trend was observed with 10-min PT. No significant difference was found in DP between 5 and 10min PT within each group.
Conclusions: Deposits on enamel-surface reduced the penetration of P₁₁-4 monomer. No added benefit was obtained with longer PT beyond 5min.