The direct application of light for photo-disinfection potentially provides a safe and novel modality to inhibit or eliminate cariogenic bacteria residing upon and within dentine. This study aimed to both; characterize the pattern of transmission of 405 nm light through molar dentine at different tooth locations, as well as, determine the irradiation parameters that are antibacterial for Streptococcus mutans under various growth conditions, including lawns, planktonic cultures, and biofilms. To determine the amount of light (405 nm) transmitted at different anatomical tooth locations; irradiance values were recorded after blue light (470–4054 mW/cm²) had traversed through occlusal, oblique, and buccal dentine sections; and three thicknesses - 1, 2 and 3 mm were investigated. To determine tubular density; scanning electron micrographs from 2 mm outer (dentine-enamel junction) and inner (pulp) dentine sections were analysed. For photo-disinfection studies; S. mutans was irradiated using the same 405 nm wavelength light at a range of doses (110–1254 J/cm²) in both biofilm and planktonic cultures. The inhibitory effect of the irradiation on bacterial lawns was compared by measuring zones of inhibition; and for planktonic cultures both spectrophotometric and colony forming unit (CFU) assays were performed. A live/dead staining assay was utilised to determine the effect of irradiation on bacterial viability in mature biofilms. Data indicated that increasing dentine thickness decreased light transmission significantly irrespective of its orientation. Occlusal and oblique samples exhibited higher transmission compared with buccal dentine. Oblique dentine 405 nm light transmission was comparable with that of occlusal dentine independent of section thickness. An increased tubule density directly positively correlated with light transmission. Irradiation at 405 nm inhibited S. mutans growth in both biofilm and planktonic cultures and a dose response relationship was observed. Irradiation at doses of 340 and 831 J/cm² led to significant reductions in bacterial growth and viability; as determined by CFU counting and live/dead staining. Data suggests that phototherapy approaches utilising a 405 nm wavelength have therapeutic potential to limit cariogenic bacterial infections both at the surface and within dentine.

直接将光用于光消毒可以潜在地提供一种安全新颖的方式来抑制或消除牙本质上及其内部的致龋细菌。这项研究的目的是为了两者；表征405 nm光在不同牙齿位置通过磨牙牙本质的透射模式，并确定在各种生长条件下（包括草坪，浮游生物和生物膜）对变形链球菌具有抗菌作用的辐照参数。确定在不同解剖牙齿位置透射的光量（405 nm）；蓝光（470–4054 mW / cm ²）穿过了牙合，斜和颊的牙本质切片；并研究了三种厚度-1、2和3 mm。测定管密度；分析了2 mm外部（牙本质-牙釉质结）和内部（牙髓）牙本质切片的扫描电子显微照片。用于光消毒研究；变形链球菌使用相同波长405nm的光在一定剂量范围（110-1254焦耳/平方厘米的照射²）在生物膜和浮游文化中都可以使用。通过测量抑制区域，比较了辐射对细菌草坪的抑制作用。对于浮游培养，则同时进行了分光光度法和菌落形成单位（CFU）分析。活/死染色测定法用于确定辐射对成熟生物膜中细菌生存力的影响。数据表明，增加牙本质的厚度会显着降低光的传输，而与方向无关。与颊部牙本质相比，咬合和倾斜样品显示出更高的透射率。斜牙本质405 nm的透射率与牙本质的咬合性相当，与切片厚度无关。肾小管密度增加直接与光透射正相关。405 nm的辐射被抑制变形链球菌在生物膜和浮游培养物中均生长，并观察到剂量反应关系。以340和831 J / cm ^2的剂量进行辐照会导致细菌生长和生存能力的显着降低。由CFU计数和活/死染色确定。数据表明，利用405 nm波长的光疗方法具有治疗潜力，可限制牙本质表面和牙本质内部的龋齿细菌感染。