The effects of some clinical procedures on the fluid contents of the dentin and pulp were studied in vitro. The method involved measurement of the movement of the meniscus in a tube and glass capillary filled with physiologic saline solution and attached to the root pulp of the extracted tooth. Drilling was found to produce expansion and an outward movement of fluid from the apex to the tooth.
SUMMARY The activity of camphorquinone (CQ) in the photoinitiation of polymerization at various conditions (in the presence or absence of atmospheric oxygen or a coinitiator) has been studied by UV spectroscopy and differential scanning calorimetry. In the latter case the polymerization kinetics of six multifunctional (meth)acrylates of various structures was followed under isothermal conditions. In the absence of a coinitiator the rate of polymerization was found to depend on the chemical structure of the monomer and its ability to donate hydrogen to exited CQ. For most of the monomers the polymerization rate in air exceeds markedly the polymerization rate in nitrogen, which is in contrast to the situation observed for the polymerization in the presence of a coinitiator (aromatic amine). The increase in the polymerization rate in the presence of atmospheric oxygen is discussed in terms of additional formation of initiating species due to *CQ-assisted decomposition of some oxidation products arising from monomer, polymer or CQ during irradiation.
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