The effect of UVC light of bovine dentine inoculated with mutans streptococci: an explorative study

Mennega, E. (2016) The effect of UVC light of bovine dentine inoculated with mutans streptococci: an explorative study. thesis, Dentistry.

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Abstract

Caries is one of the most common dental diseases and the most important cause of dental pain. S. mutans and S. sobrinus, belonging to the group mutans streptococci, have a high cariogenicity. There are several methods to eliminate oral bacteria. What if ultraviolet (UV) light could eliminate bacteria present in residual caries, without removing additional dentine? UV light has a spectrum between 100-400 nm. For ultraviolet B (UVB) and ultraviolet C (UVC) light the wavelengths are respectively between 280-320 nm and 200-280 nm, which have the highest bactericidal effect. Prior studies researched the effect of UVC light on toothbrushes. This study strives to assess whether there is an antibacterial effect of UVC light on bovine dentine inoculated with S. mutans and S. sobrinus. This study was an experimental in vitro research, using bovine teeth. In the experiments, dentine coupes (n = 62) were inoculated with two oral bacteria, S. mutans and S. sobrinus. For both bacteria, two experimental conditions were used: exposure to UVC light and a control group (no exposure to UVC light). Prior to initiating the experiment, the optimal thickness of dentine coupes for UVC radiation (transmittance of UVC light through dentine) was analysed. In a pilot study, the optimal method for detecting the effect of the intervention (UVC radiation) and the optimal UVC dose were evaluated. Statistical analyses were carried out using Kendalls’s Tau, the Kruskal-Wallis, and Mann-Whitney U test (alpha = 0.05). Results of both the pilot study (planktonic bacteria) and the dentine coupe experiment showed a significant reduction in the amount of viable bacteria when comparing the control group to the radiation group. However, only the UVC radiated planktonic S. mutans showed a clinically relevant reduction in bacteria when compared to the control group. The results of this study provided a variety of data. For planktonic S. mutans the appropriate UVC dose is 8800 μWs/cm2. The S. sobrinus showed to be less susceptible to the effect of UVC radiation. An appropriate UVC dose for S. sobrinus has not yet been found. Furthermore, this study presented information showing small amounts of UVC light penetrate bovine dentine. Overall the conclusion of this study is that UVC light has a bactericidal effect on the mutans streptococci, S. mutans and S. sobrinus, particularly on the S. mutans. When dentine coupes are inoculated with the bacteria, the radiation mainly affects the bacteria on the surface on the dentine coupe. Therefore this is not clinically relevant.

Item Type:	Thesis (Thesis)
Supervisor name:	Hoogmoed, dr. C.G. and Kaper, drs H.J.
Faculty:	Medical Sciences
Date Deposited:	25 Jun 2020 11:00
Last Modified:	25 Jun 2020 11:00
URI:	https://umcg.studenttheses.ub.rug.nl/id/eprint/2001

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