Effect of nano-hydroxyapatite toothpaste on microhardness of artificial carious lesions created on extracted teeth

Abstract

Background. Many types of toothpastes contain substances that can remineralize initial enamel caries. This study aimed to assess the effect of nano-hydroxyapatite (NHA) on microhardness of artificially created carious lesions.Methods. In this in vitro study, NHA was prepared using sol-gel technique and added to the toothpaste with 7% concentration. A total of 80 extracted sound teeth were collected. The crowns were polished using 500-grit abrasive paper. The specimens were randomly coded from 1 to 80. Number 1 to 40 were assigned to group A and numbers 41 to 80 to group B. The microhardness was measured using HVS-1000 Vickers microhardness tester. The specimens were demineralized using 37% phosphoric acid for 3 minutes in order to create artificial carious lesions and then were rinsed with water, air-sprayed for 3 minutes and dried. Microhardness was measured again. Next, the specimens were brushed for 15 days, twice daily, for 15 seconds. After 15 days, microhardness was measured again. Toothpaste A contained NHA and fluoride and toothpaste B contained fluoride alone. Data were analyzed using SPSS 16, with one-sample Kolmogorov-Smirnov test and ANOVA at a significance level of P<0.05.Results. The microhardness of specimens significantly decreased following acid exposure (P<0.01) but increased again in both groups after exposure to toothpastes. The increase in microhardness was significantly greater in group A (P<0.01).Conclusion. The toothpaste containing NHA was more effective than the toothpaste without NHA for the purpose of remineralization.

The effect of combining laser and nanohydroxy-apatite on the surface properties of enamel with initial defects

“…In addition, apatite formed in an environment containing more calcium and phosphate is expected to contain less CO2 and less Mg by replacing them with calcium and phosphate, making enamel more acid resistant and increasing its surface hardness levels ( 12 ). This result is in agreement with Swarup JS et al ( 1 ), Rathi N et al ( 13 ), and Ebadifar A et al ( 7 ).…”

“…Results of microhardness testing showed that Demineralization resulted in significant reduction on mean Hardness (220.15±2.77 VHN) compared to Baseline (283.97±10.83 VHN), which might be contributed to enamel weakness by increased pore size due to mineral removed from the enamel surfaces as a result of dissolution of hydroxyapatite. There was a significant increase of microhardness of the enamel surface after being treated with nano hydroxyapatite whether the pure type (293.6±5.97 VHN) or the flouro apatite (279.81±8.36 VHN) one, indicating that nHAP induces a consistent enamel remineralization by forming a homogenous apatite layer on the demineralized surfaces of enamel after treatment, which can be explained by the facts of ; NHA has hydrophilic and wetting characteristics and is capable of producing a thin but tightly bound layer on the tooth surface, resulting in higher surface hardness and remineralization ( 7 ). Besides, nano-hydroxyapatite also acts as filler because it repairs small holes and depressions on enamel surface, a function enhanced by the small size of the particles that compose it ( 6 ).…”

“…Since that hydroxyapatite (HA) is the main component of enamel, which gives an appearance of bright white and eliminates the diffuse reflectivity of light by closing the small pores of the enamel surface, ( 6 ) it is one of the most biocompatible and bioactive materials. It has a non-toxic, non-irritant, non-allergenic, non-mutagenic, non-carcinogenic property and anti-bacterial effect ( 7 ). In recent years, biomimetic approaches have been used to develop nano-materials for the reminerlization of early enamel lesions ( 8 ).…”

Nanoparticles as Anti-Microbial, Anti-Inflammatory, and Remineralizing Agents in Oral Care Cosmetics: A Review of the Current Situation

“…The caries incidence decreased by 56% in children brushing with a HA NP toothpaste compared to the group brushing with a control toothpaste [242]. Several in vitro studies reported the efficacity of HA NPs in the remineralizing process [240,[243][244][245]. HA NP toothpaste as remineralizing paste showed better results when compared to toothpaste containing calcium and potassium ions and sodium nitrate [246].…”

Synthesis of plate-like β-tricalcium phosphate nanoparticles and their efficiency in remineralization of incipient enamel caries

“…Among many materials explored to provide bioavailable calcium and phosphate ions for the remineralization process, crystalline calcium phosphates such as nanohydroxyapatite (Ebadifar et al 2017;Mielczarek and Michalik 2014), β-tricalcium phosphate (β-TCP) (Karlinsey and Pfarrer 2012), amorphous calcium phosphate (ACP) (Mundorff-Shrestha et al 1998;Thompson et al 1999), calcium sodium phosphosilicate bioactive glass (Novamin) (Burwell et al 2009), and casein phosphopeptide amorphous calcium phosphate (CPP-ACP) (Cochrane et al 2012;Li et al 2014) have drawn considerable attention due to their biocompatibility, chemical stability, wear resistance, and chemical and structural similarity to natural enamel hydroxyapatite (Cochrane et al 2010). The main limitation of the calcium salts in oral environment is, however, their low solubility, which limits their bioavailability (Eden 2016).…”