Dentine Tubule Occlusion by Novel Bioactive Glass-Based Toothpastes

Abstract

There are numerous over-the-counter (OTC) and professionally applied (in-office) products and techniques currently available for the treatment of dentine hypersensitivity (DH), but more recently, the use of bioactive glasses in toothpaste formulations have been advocated as a possible solution to managing DH. Aim. The aim of the present study, therefore, was to compare several bioactive glass formulations to investigate their effectiveness in an established in vitro model. Materials and Methods. A 45S5 glass was synthesized in the laboratory together with several other glass formulations: (1) a mixed glass (fluoride and chloride), (2) BioMinF, (3) a chloride glass, and (4) an amorphous chloride glass. The glass powders were formulated into five different toothpaste formulations. Dentine discs were sectioned from extracted human teeth and prepared for the investigation by removing the cutting debris (smear layer) following sectioning using a 6% citric acid solution for 2 minutes. Each disc was halved to provide test and control halves for comparison following the brushing of the five toothpaste formulations onto the test halves for each toothpaste group. Following the toothpaste application, the test discs were immersed in either artificial saliva or exposed to an acid challenge. Results. The dentine samples were analyzed using scanning electron microscopy (SEM), and observation of the SEM images indicated that there was good surface coverage following artificial saliva immersion. Furthermore, although the acid challenge removed the hydroxyapatite layer on the dentine surface for most of the samples, except for the amorphous chloride glass, there was evidence of tubular occlusion in the dentine tubules. Conclusions. The conclusions from the study would suggest that the inclusion of bioactive glass into a toothpaste formulation may be an effective approach to treat DH.

Figure 1

SEM images of the dentine surface morphology in disc 1 treated with a 45S5 glass-based toothpaste at 5000x (top) and 10000x (bottom) magnifications. (a) Control; (b) after brushing with a bioactive glass-based toothpaste; (c) after brushing with a bioactive glass-based toothpaste + artificial saliva immersion for 1 hour; (d) after brushing with a bioactive glass-based toothpaste + acid challenge with 6% citric acid.

Figure 2

SEM images of the dentine surface morphology in disc 2 treated with a mixed glass-based toothpaste at 2000x (top) and 5000x (bottom) magnifications. (a) Control; (b) after brushing with a bioactive glass-based toothpaste; (c) after brushing with a bioactive glass-based toothpaste + artificial saliva immersion for 1 hour; (d) after brushing with a bioactive glass-based toothpaste + acid challenge with 6% citric acid.

Figure 3

SEM images of the dentine surface morphology in disc 3 treated with a BioMinF glass-based toothpaste at 5000x (top) and 10000x (bottom) magnifications. (a) Control; (b) after brushing with a bioactive glass-based toothpaste; (c) after brushing with a bioactive glass-based toothpaste + artificial saliva immersion for 1 hour; (d) after brushing with a bioactive glass-based toothpaste + acid challenge with 6% citric acid.

Figure 4

SEM images of the dentine surface morphology in disc 4 treated with a chloride glass-based toothpaste at 5000x (top) and 10000x (bottom) magnifications. (a) Control; (b) after brushing with a bioactive glass-based toothpaste; (c) after brushing with a bioactive glass-based toothpaste + artificial saliva immersion for 1 hour; (d) after brushing with a bioactive glass-based toothpaste + acid challenge with 6% citric acid.

Figure 5

SEM images of the dentine surface morphology in disc 5 treated with an amorphous chloride glass-based toothpaste at 5000x (top) and 10000x (bottom) magnifications. (a) Control; (b) after brushing with a bioactive glass-based toothpaste; (c) after brushing with a bioactive glass-based toothpaste + artificial saliva immersion for 1 hour; (d) after brushing with a bioactive glass-based toothpaste + acid challenge with 6% citric acid.

Figure 6

Percentage of open tubules (), partially occluded tubules (), and occluded tubules () present after different treatments.