Title: A novel device for phototherapy to promote tissue repair
Funder: Department of Health (England)

Abstract: Fundamental biological processes affected by light radiation Initial stages of the project will utilise in-vitro high-throughput screening of pulpal cells and oral bacteria associated with carious disease and restoration failure to identify optimal radiation conditions which promote tissue repair. Initially, a bespoke design of multiple light-emitting diodes arranged in serial alignment will enable high-throughput analyses within multi-well culture plates to efficiently determine candidate wavelengths and exposure conditions for subsequent design of the prototype device. Readouts in bacterial cells will include cell growth inhibition assays, whilst in pulpal cells, proliferation and mitochondrial/metabolic activity will be assessed. In addition, cytoprotective and anti-inflammatory activity of the irradiation conditions will be examined in pulpal cells exposed to toxic components from routinely used dental materials. Light penetration through dentine will also be examined, as stimulation of cellular repair activity will be beneficial in cavities with remaining dentinal coverage. To develop the potential clinical application, irradiation exposure effects in ex-vivo tooth organ cultures (containing infected/restored artificial cavities) will be studied. Readouts will include cellular repair activity and viability determined by histological examination. Irradiation exposure regimes will be applied using the conditions identified from in-vitro analyses. Milestone: Identification of light irradiation conditions which promote ex-vivo tooth repair. Design and development of a novel light therapy device The observed effects of light on biological processes will underpin the development of a novel handheld therapeutic prototype device assisted by an internationally reputed medical equipment company (Satelec) who are a global leaders in the manufacturer of innovative light technology. While the effects of low-level light therapy (LLLT) are not well known in the dental field, in other healthcare fields where this technology is more routinely applied there also exist many unknown aspects concerned with inappropriate light measurement and its application resulting in misleading effects on cellular response. The project will therefore aim to interrogate these confounding factors, which are crucial for this development. This work will therefore have tremendous translational potential for healthcare services that utilize LLLT, and are outlined by the following deliverables: i) Exposure reciprocity and optimum light delivery The therapeutic effect of total light energy, a product of light irradiance and duration, or radiant exposure will be investigated . A range of wavelengths will be explored (400-1000nm using LEDs at ~25nm intervals) and for those that provide significant effects, various radiant exposures will be tested (100-1000mJ/cm2) with different combinations of irradiance (5-20mW/cm2) and duration (20-120s). The effect of increasing irradiance and proportionally decreasing exposure time will be studied to assess whether equivalent cell response is obtained for similar radiant exposure regardless of irradiance or time, which will provide the most effective and time-efficient delivery. All LED arrangements will be characterized in terms of wavelength, power, stability and heat output to determine any effect on stimulatory/inhibitory cell processes and light-output performance. ii ) Beam profile design and optimum light dispersion The light delivered from conventional optics is not distributed evenly due to the inhomogeneous beam profile. Higher irradiance towards the cells in the centre of a sample may lead to erroneous results in vitro and reduce therapeutic effectiveness. This project will investigate methods to eliminate beam profile inhomogeneity using various optical arrangements, lenses and diffusers to create a ‘top-hat’ light distribution in order to optimize the therapeutic effect of irradiation. Our industrial partner, with >20 years of experience in commercial development of dental electronic equipment and imaging technology will assist us in the most effective functional design of the prototype handheld device to enable successful delivery of the project milestones. Milestone: Development of a prototype device that enables effective light therapy to accelerate dental tissue repair.


Research activity codes: 5.4 SURGERY
Health categories: ORAL AND GASTROINTESTINAL