Shortening the light emission and exposure widths to the infinitesimal time, the impulsive light emission l(t) and the exposure g(t) can be regarded as the delta function δ(t).
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Within the limitations of the present study it can be concluded that shortening the light exposure time, while maintaining the energy density, resulted in no higher cytotoxicity of the surface sealants cured in this manner.
The hypothesis of the present study was that (1) shortening the light-curing time while simultaneously increasing light intensity results in a higher cytotoxicity of the surface sealants and (2) that the type of sealer has an influence on cytotoxicity.
The primary hypothesis of the present study, that shortening the light-curing time while simultaneously increasing the light intensity results in a higher cytotoxicity of the surface sealants, has to be rejected as no significant influence of the light-curing settings on the cytotoxicity was observed, neither for the dental pulp cells nor for the gingival fibroblasts.
Therefore, the aim of the present study was to investigate whether shortening the light-curing duration (while maintaining similar energy density by simultaneously increasing the light-curing intensity) would have an influence on the cytotoxicity of two tested surface sealants.
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Shortening the light-curing time, while maintaining constant energy density, resulted in no higher cytotoxicity of the investigated sealants.
We assume that there are two possible explanations for these contrary findings: On one hand, the light-curing time was shortened, but simultaneously, the light-curing intensity was increased, resulting in an application of similar energy densities, while in the above mentioned studies only the light curing time was shortened.
To the present, no study has been published that examines the use of increased light intensity to compensate for the negative side effects (increased cytotoxicity) of a shortened light-curing duration of surface sealants.
