The influence of a simulated pulsatile pulpal pressure on the diffusion of NaCl through slices of human dentine (n = 12) was evaluated in vitro. The average hydraulic conductance of the slices of dentine was 0.0131 +/- 0.0031 microliter/cm2 per min per cmH2O(x +/- SD). A 1 mol/l NaCl solution was placed on one side of the slices of dentine and deionized water on the other side. The time needed to reach a steady state and the quantity of NaCl that diffused through the slice were successively measured on the same slice of dentine, under three conditions: without pressure simulation, with a static pressure of 1.5 kPa, and with a pulsatile pressure varying from 1.2 to 1.8 kPa. The pressure was applied to the deionized water. When a static pressure was applied, the time required to reach a steady state increased from 24 to 30 h. When a pulsatile pressure was applied the time required to reach a steady state decreased from 24 to 12 h. No statistically significant difference was found between the quantity of NaCl that had diffused when the steady state was reached.

Analysis of Variance↗

PubMedDate not supplied

Relationship between dentine hydraulic conductance and the cytotoxicity of four dentine bonding resins in vitro.

OBJECTIVES: Dentine modifies pulpward diffusion of monomers leaching from restorative materials. Thus, remaining dentine thickness must be taken into account during in vitro cytotoxicity tests. This in vitro study was designed to determine the influence of dentine permeability on the outcome of a cytotoxicity test. METHODS: Dentine slices were made from 36 human third permanent molar teeth. The 36 dentine slices were divided into two groups according to their hydraulic conductance: high or low hydraulic conductance. The cytotoxicity of four dentine bonding agents of similar cytotoxicity was tested on dentine slices from each group. Four dilutions of the experimental culture medium were tested: undiluted, 1:2, 1:10 and 1:100. An analysis of variance was used to compare the cytotoxicity of the dentine bonding agents tested on high versus low hydraulic conductance. RESULTS: The cytotoxicity of the high hydraulic conductance (Lp) group was higher than that of low Lp group when tested with the undiluted test culture medium (p = 0.001). No difference was obtained with the 1:2, 1:10, 1:100 dilutions. CONCLUSIONS: Under the conditions of the study, the dentine bonding resins were more cytotoxic when applied onto dentine slices of high hydraulic conductance.

Analysis of Variance↗

PubMedDate not supplied

Pulpal inflammatory responses following non-carious class V restorations.

The effects of inflammatory activity following surgical intervention can injure pulp tissues; in severe cases it can lead to pulpal complications. With this article, the authors report on the effects of cavity preparation and restoration events and how they can interact together to reduce or increase the severity of pulpal inflammatory activity in 202 restored Class V cavities. Although some inflammatory activity was observed in the absence of bacteria, the severity of pulpal inflammatory activity was increased when cavity restorations became infected. Zinc oxide eugenol and resin-modified glass ionomer cement prevented bacterial microleakage in cavity restorations, with no severe inflammatory activity observed with these materials. Bacteria were observed in cavities restored with enamel bonding resin and adhesive bonded composites and were associated with severe grades of inflammatory activity. The cavity remaining dentin thickness influenced the grade of inflammatory activity. In the absence of infection, the grade of inflammatory activity decreased after 20 weeks post-operatively. In the presence of infection, the grade of pulpal inflammation remained stable until a minimum of 30 weeks had elapsed.

Adolescent↗