Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - PRe-FActo (Periodontal Regeneration through Femtosecond laser Action)

Teaser

Periodontitis (PD) is an inflammatory disease affecting the tissues that support the teeth. The condition begins when bacteria grow on teeth surface forming microbial plaque (fig 1). An over-aggressive immune response against these, leads to chronic inflammation of the...

Summary

Periodontitis (PD) is an inflammatory disease affecting the tissues that support the teeth. The condition begins when bacteria grow on teeth surface forming microbial plaque (fig 1). An over-aggressive immune response against these, leads to chronic inflammation of the periodontal tissues and the destruction of the periodontal ligaments. If left untreated PD leads to tooth loss [1] while, current evidence associate PD with systemic health of patients (e.g. cardiovascular diseases) [2].

Periodontitis is regarded as a global problem which is acute in both young adults and ageing population. It starts early in individual’s life as gingivitis (the first stage of periodontitis) affects children between 14-17 years old. The severity of the disease increases with age and thus extensive attachment loss (>4 mm) is observed for ages between 30 and 45 while, tooth loss is more pronounced for ages >50 [3]. Based on the presence of periodontal pockets ≥4 mm, it was determined that 30% of the US population has periodontitis on an average on three to four teeth. Epidemiological research in Europe, revealed that Spain, Sweden, and Switzerland ranked as the healthiest among European countries as CAL between 4 and 5 mm has been observed in 20-27% of the subjects tested (ages between 35 to 44 years old) [4]. Although it is difficult to calculate the exact amount spent for periodontitis treatment, it is estimated that the 27 EU member states has spent almost €79 billion on oral health in 2012 which is likely to rise to €93 billion by 2020 [4].

The ultimate goal of periodontal therapy is to prevent further attachment loss and predictably restore the periodontal structures that were lost because of the disease. The most popular strategies include: stem cells delivery, soft tissue grafts, bone grafts, and growth/ differentiation factors. By reviewing these techniques it can be concluded that although there is some regenerative potential, still there is no evidence for sufficient tissue attachment. Depending on the applied technique various toxicity issues and lack of growth related reattachment arise and hinder the periodontal regeneration. The two most important factors which affect the majority of the aforementioned techniques are: A) The oral bacterial which are attached on the tooth surface and lead to contamination. B) The formation of a junctional epithelium which is not practically attached to the tooth surface.

PRe-FActo aims to address the majority of these problems and to establish the foundations for a new regenerative strategy of the periodontal tissues. The proposed procedure is based on the use of femtosecond lasers in order to attach a new layer of a calicium phosphate on the surface of dental enamel (close to the gums). This can be described by the following steps (fig 2):
a) Fill the periodontal (PD) pockets with a thin layer of hybrid bio-material (Sr and Ce ions doping for antibacterial properties).
b) Bond this material onto the surface of the root after irradiating with a femtosecond laser.
c) Coating with a chitosan layer in order to promote the growth of fibroblasts and support PD regeneration. Chitosan is not only a biocompatible material with antibacterial properties but also can be used as carrier for different proteins and growth factors.

References
[1] Savage, A., et al., A systematic review of definitions of periodontitis and methods that have been used to identify this disease. Journal of Clinical Periodontology, 2009. 36(6): p. 458-467
[2] Cullinan, M.P., P.J. Ford, and G.J. Seymour, Periodontal disease and systemic health: current status. Australian Dental Journal, 2009. 54: p. S62-S69.
[3] Genco, R.J. and R.C. Williams, Periodontal Disease and Overall Health: A Clinician’s Guide. 2010: Professional Audience Communications, Inc.
[4] Patel, R., The State of Oral Health in Europe. Technical Report, 2012.

Work performed

The most crucial part of the proposed treatment strategy was to demonstrate the attachment of a new layer of biomaterial on the surface of dental enamel. In a recent publication we present how femtosecond lasers can be utilised for the exogenous mineralisation of hard tissues (fig. 3).
In genral a radical new methodology for the exogenous mineralization of hard tissues is demonstrated in the context of laser-biomaterials interaction. The proposed approach is based on the use of femtosecond pulsed lasers (fs) and Fe-doped calcium phosphate minerals (fluorapatite powder containing Fe2O3 nanoparticles (NP)). A layer of the powder is applied to the surface of eroded bovine enamel and is irradiated with a fs laser (1040 nm wavelength, 1 GHz repetition rate, 150 fs pulse duration and 0.4 W average power). The Fe2O3 NPs absorb the light and may act as thermal antennae, dissipating energy to the vicinal mineral phase. Such a photothermal process triggers the sintering and densification of the surrounding calcium phosphate crystals thereby forming a new, dense layer of typically ̴20 μm in thickness, which is bonded to the underlying surface of the natural enamel. The dispersed iron oxide NPs, ensure the localization of temperature excursion, minimizing collateral thermal damage to the surrounding natural tissue during laser irradiation. Simulated brushing trials (pH cycle and mechanical force) on the synthetic layer show that the sintered material is more acid resistant than the natural mineral of enamel. Furthermore, nano-indentation confirms that the hardness and Young’s modulus of the new layers are significantly more closely matched to enamel than current restorative materials used in clinical dentistry.

Final results

Although the developed treatment strategy is still several steps away from clinical translation, eventually it is expected to delay the symptoms of periodontitis and thus the cost oral health care is likely to be reduced for patients benefit. The consequential cost repercussion on chronic disease which are apparently linked with periodontitis (glycaemic control, CVD) are also likely to reduce for the care of risk factor patients. Comparing with the existing treatment strategies, the main advantage of our solution is that the natural teeth of the patients will be the scaffold for PD regeneration by applying a “regenerative” layer with antibacterial properties which will promote the restoration of the damaged PD ligaments. Another benefit is the proactive character of the developed technology. The application of a thin film of the sintered biomaterial (with the antibacterial properties) on the surface of the tooth at the very beginning of the disease could prevent the accumulation of the bacterial plaque, stop the periodontitis progression and protect the systemic health of the patients. Consequently, the exact same technique could be used not only for the treatment but also for the prevention of the disease.
The most significant achievement of my research was to demonstrate the exogenous mineralisation of hard tissues using femtosecond lasers. The ability to attach a new layer of calcium phosphate on enamel could be the stepping stone for direct additive manufacturing on hard tissues (3d printing). Such a capability could find various applications in the field of tissue engineering.

Website & more info

More info: https://aanastasiou83.wixsite.com/prefacto.