Photo-Activated Phosphate Minerals and Femto-Second Pulsed Near-IR Lasers for the Restoration of Damaged Dental Enamels

Clinical Need: Ageing and lifestyle are two commonly known factors that determine the health of dental enamel. Consumption of acidic food and beverages with low pH (<5), stomach acid reflux, underlying health condition and aggressive brushing adversely affect the longevity of enamel mineral. Acid erosion of enamel is a common condition in global population, and if not treated, may lead to compromised dietary intake, which may compromise long-term health. Anatomically, the dental enamel is an acellular-avascular tissue, containing more than 95% hydroxyapatite mineral on surface which protects the underlying soft dentine and sub structural soft tissue, essential for maintaining tooth vitality. Since the microvasculature network terminates below the dentine layer, the enamel layer lacks the intrinsic regenerative capacity due to the lack of nutrient supply. Consequently, the oral acid induced erosive damage on enamel is irreversible, and leads to lesion formation, which if unattended, may lead to hypersensitivity and feeling of pain. Advanced stage of eroded enamel with symptoms of hypersensitivity might lead to tooth loss in adults. The treatment plan for eroded enamel, shown in the Figure 1, is based on the use of off-the-shelf hypersensitive toothpastes and BIS-GMA polymeric materials; the latter is structurally incompatible with natural enamel due to mismatched thermal expansion coefficient and mechanical properties. As a result, the BIS-GMA type of bonding leads to failure of restored enamel area in a challenging oral environment [1]. By comparison, the toothpastes only provide temporary symptomatic relief from hypersensitivity. Till date, no long-term or permanent solution for treating early stages of acid erosion is on offer. Associated with acid erosion is also erosive wear which affects especially the ageing population and leads to lingual tooth thinning and weakening. Rebuilding the entire damaged tissue region remains a challenge.