Nanotechnology in ligature-induced periodontitis: protective effect of a doxycycline gel with nanoparticules

Abstract

Objectives: The aim of this study was to test the efficacy of a locally applied 8.5% nanostructured doxycycline (DOX) gel in preventing alveolar bone loss in experimental periodontal disease (EPD) in rats by using the tapping mode atomic force microscopy (AFM).

Material and methods: EPD was induced in 24 Wistar rats. Animals were treated with the doxycycline gel topically, immediately after EPD induction, and 3 times a day during 11 days. Four groups (n=6) were formed as follows: Naïve group (animals not subjected to EPD nor treated); non-treated (NT) group (animals subjected to EPD, but not treated); vehicle gel (VG) group (animals subjected to EPD and treated with topical gel vehicle); and DOX group (test group): animals subjected to EPD and treated with the 8.5% DOX gel. In order to investigate topographical changes in histological sections, a novel simple method was used for sample preparation, by etching sections from paraffin-embedded specimens with xylol.

Results: Comparing the AFM images, several grooves were observed on the surface of the alveolar bone and other periodontal structures in the NT and VG groups, with significantly greater depths when compared to the DOX group (p<0.05).

Conclusions: Periodontal structures were brought into high relief confirming to be a simple and cost-effective method for AFM imaging with ultrastructural resolution. The doxycycline gel was able to afford periodontal surface preservation, with flatter grooves.

Figures

Figure 1

Macroscopic aspects of the effect of a nanostructured 8.5% Doxycycline (DOX) locally applied gel (Dental gel®) on alveolar bone loss. Experimental periodontal disease was also induced in the animals from the Non-Treated (NT) and in vehicle (V) groups. Naïve group was not submitted to EPD and received no treatment. Bars represent the mean ± Standard Error of Mean (SEM) of alveolar bone loss (mm; N=6). Asterisk indicates a statistically significant difference between the DOX group and NT group (*P<0.05; Bonferroni, ANOVA)

Figure 2

Macroscopic aspects of the effect of c on experimental periodontal disease in rats. A: macroscopic aspect of a normal periodontium of rat maxillae showing healthy periodontal structures; B and C: periodontium of rats subjected to induction of experimental periodontitis with no treatment (NT) and vehicle gel treatment, showing severe alveolar bone loss

Figure 3

Effect of 8.5% DOX gel on myeloperoxidase (MPO) activity in the maxillary gingival tissue of rats submitted to experimental periodontal disease (EPD). Vehicle (V) gel and Doxycycline (DOX) gel were administered topically in animals subjected to EPD induction. EPD was induced also in Non-Treated (NT) animals and Naïve group received no treatment and was not submitted to EPD induction. Bars represent mean ± Standard Error of Mean (SEM) of the activity of MPO/mg of tissue. *P

Figure 4

Effect of 8.5% Doxycycline (DOX) gel on alveolar bone surface roughness in rats subjected to experimental periodontal disease (EPD). The AFM image from the DOX group shows a regular bone surface covered with a shallow defined layer

Figure 5

Chosen areas to evaluate the topographical changes in alveolar bone of rats subjected to the experimental periodontitis disease EPD treated with vehicle gel

Figure 6

Effect of 8.5% Doxycycline (DOX) gel on the alveolar bone loss in alveolar bone roughness analysis by AFM in rats with experimental periodontal disease (EPD). The 8.5% DOX gel was administered topically, daily, in animals subjected to the EPD. Bars represent the mean ± Standard Error of Mean (SEM) of alveolar bone loss (mm; N=6). Asterisk indicates a statistically significant difference between treated group and Non-Treated (NT) group (*P

Figure 7

Topographical changes in alveolar bone surface of rats subjected to experimental periodontitis disease EPD and treated with 8.5% Doxycycline (DOX) gel

Figure 8

Topographical changes in alveolar bone surface of rats subjected to experimental periodontitis disease EPD treated with the vehicle gel

Figure 9

Histopathology from the periodontium of rats subjected to periodontitis. 8.5% Doxycycline (DOX) gel was administered topically immediately after ligature placement and daily after periodontitis induction for 11 days. Photomicrograph of the region between the first and second molars of rats: A represents the region evaluated in all groups. Hematoxylin-Eosin (HE) staining