New-Generation Biomimetic Hydroxyapatites

Next-Generation Biomimetic Hydroxyapatites Dental health being a priority, active ingredients for oral care have developed significantly over the past decade. Recently, remineralizing substances have been based on hydroxyapatite (HAP), a mineral naturally present physiologically in dental tissue, gum and dentin derivatives. Two main strategies are typically applied in tooth remineralization: the first involves fluoride-based active ingredients, the second addresses Ca⁺⁺ and PO₄ - sources. Teeth are composed of a rich and continuously changing mineral phase characterized by the presence of HAP at 97% of total composition in dental tissue and gum and 70% in dentin respectively. Remineralization is a process in which the tooth mineral phase is subjected to a recovery phase as a physiological homeostasis and balance mechanism against continuous daily demineralization. The term "biomimetic" refers to studies addressing the formation, structure or function of biologically produced substances and biological mechanisms and processes aimed at synthesizing similar products that imitate natural products. The following recommendations meet the biomimetic concept through different modalities and effectively respond to functional requirements aimed at preventing caries, hypersensitivity and whitening effects before they occur. • Biomimetic hydroxyapatite, • Fluorohydroxyapatite, • Amorphous calcium phosphate functionalised with citrates, fluoride and carbonate ions. Biomimetic HAP composition analysis was performed by X-ray diffraction. Testing conducted over 28 days, twice daily at 5% concentration in toothpaste formulation on 50 volunteers aimed to evaluate the effect of reducing hypersensitivity through subjective assessment. Subjective assessment was performed on a toothpaste containing 4% biomimetic HAP to measure whitening effect. In vivo tests were conducted on a toothpaste containing 6% biomimetic HAP and fluorohydroxyapatite compared to a control reference containing a remineralizing active ingredient plus 1,500 ppm fluoride as comparison product. Following a three-day treatment applied to 45 subjects with positive anamnesis for hypersensitivity, a tactile stimulus was applied to volunteers' teeth with a blinded probe. Hypersensitivity score was reported according to VAS (visual analog scale): scores of 0 to 1 for no pain, 2 to 3 for mild pain, 4 to 6 for moderate pain and 7 to 10 for severe pain. Images were obtained from ex vivo tests conducted on bovine teeth to observe the complex behaviour of functionalised amorphous calcium phosphate (F-ACP). Images could be observed at different resolutions (5.0 and 15.0K); to emphasize new mineral phase accumulation on the tooth surface, differences were examined between teeth after 1-2 week treatment with a toothpaste containing 10% F-ACP solution and demineralised teeth following acid treatment. Conducted studies confirmed that biological compatibility of hard surfaces and material adhesion were improved. This validates that HAP can readily bind to substrates such as tooth biofilm glycoproteins and microlysions. Different surface structure also distinguishes stoichiometric and biomimetic HAP in terms of crystalline index. Crystalline phase is more prominent in stoichiometric HAP and determines different reactivity. Substances with lower crystalline structure such as biomimetic HAP increase capacity for balanced, pH-dependent and long-term release of Ca⁺⁺ and PO₄ - ions in saliva that can be utilised in the remineralization cycle. Biomimetic HAP reactivity is a fundamental element used in bone prosthesis design; it emphasises biological compatibility and safety. Previous studies have shown that HAP supports more effective mineral accumulation in teeth compared to compared Ca⁺⁺ and PO₄ - based materials. The Biomimetic HAP presented here was subjected to certain tests that would define its chemical structure and functional properties when added to toothpaste. In the following study, X-ray diffraction analysis comparison between biomimetic, physiological and stoichiometric HAP is presented. Biomimetic HAP presents peak points similar to HAP expressed in the human body. This validates its similar structure, particularly in relation to the detection of CO₃- ions in OH^- vacant regions. This pattern contrasts with significantly different peak points observed with the stoichiometric form. This suggests meaningful differences exist in the product's compositional background. The reactive structure of biomimetic HAP explains its tendency to release remineralization ions in saliva through a pH-dependent mechanism. Solubility tests emphasised very low reactivity at pH values around 7.0 and slow and steady release at values below 5.5, which are critical for demineralization.

Three different approaches were evaluated in remineralization.

In vacancies within OH^- regions, biomimetic HAP has demonstrated suitability for daily oral care routine to support intelligent, balanced and long-term remineralization aimed at reducing hypersensitivity in teeth, preventing caries initiation and enhancing tooth whitening effect. Through biomimetic behaviour evaluated by its compatibility with the tooth surface in terms of adhesion, hydroxyapatite presents significant potential for application in serious dental microlysions due to its resistance to acid attacks and gum-strengthening properties, and constitutes a state-of-the-art treatment approach against caries and acid attacks. The hydroxyapatite complex, through patented technology aimed at optimizing active ingredient delivery to teeth, enables instant tooth remineralization in anhydrous toothpaste formulation and is effective in professional and daily treatments following tooth cleaning or in serious hypersensitivity or anti-caries treatments.