PubMed · 5338134
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T Berg, W W Chase, K Ray. 1967. Denture base pressure tests.. https://doi.org/10.1016/0022-3913(67)90123-0
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The influence of propylene glycol (PG) on the in vitro penetration of diclofenac sodium (DFS) through a synthetic membrane and abdominal rat skin from carbopol gels was investigated using Franz-type diffusion cells. The combined effect of isopropyl myristate (IPM) and PG was also evaluated. It was found that the penetration through the synthetic membrane was well described by the Higuchi model. The gel containing 40% PG showed the highest release rate, indicating that a releasing maximum exists for PG content which provides the fully solubilized drug in the vehicle. When using rat skin as the barrier, the penetration rate was controlled by the membrane. DFS flux decreased with increasing PG content of the gels due to an increase of the drug affinity to the vehicle. A cosolvent action of PG was evident. However, the combination of PG and IPM resulted in a synergistic enhancement of DFS flux. Maximum enhancing activity was obtained from gels containing 40% PG, which yielded an enhancement ratio of about 8. Increasing IPM content from 3 to 5% increased the flux and decreased the lag time taken to reach a steady-state level.
Ketoprofen alone and in binary mixtures with Eudragit S100 was compacted by an ultrasound-assisted (US) tableting machine at an energy ranging from 50 to 400 J. The final material was analysed by TLC and HPLC: no decomposition product of the active agent was found. IR spectra and HSM revealed the absence of any interaction between the two components. Thermal analysis (DSC) evidenced that ketoprofen inside the mixtures was transformed into an amorphous state, documented by the decreasing of the DeltaHfus as the Eudragit/ketoprofen ratio increases and as US energy increases. While pure ketoprofen recovers its crystalline state quickly after the US treatment, the presence of Eudragit was found to slow down or possibly to prevent the regeneration of the crystallinity.
STATEMENT OF PROBLEM: The Kevloc bonding system is based on the bond of acrylic resin with the metal surface, in contrast to the Silicoater system, which covers the metal surface with a SiOx-C layer. Bonding prevents the occurrence of the marginal gap between the metal and the resin, which causes weaker bond strengths and discoloration. PURPOSE: This investigation examined the bond strength values achieved by using the Kevloc technique on Ag-Pd and Co-Cr alloys, and compared them with those obtained by the Silicoater technique. After artificial aging, shear testing of the specimens was performed. MATERIAL AND METHODS: A microscope image analyzer measured the thickness of bonding layers to reveal any marginal gap. RESULTS: No marginal gap was noticed for either technique. The Kevloc technique provided better results than Silicoater regardless of alloy used. Immersion in water (7.64 to 8. 05 MPa) and thermocycling (6.12 to 6.95 MPa) reduced the initial bond strength values (12.52 to 12.94 MPa), but the breakdown occurred between the opaque layers or between the opaque and the resin, thus giving a cohesive type of failure. CONCLUSION: The dental alloy used did not affect bond strengths and artificial aging caused reduction in bond strengths. The Kevloc bonding system exhibited higher bond strengths than Silicoater, but the marginal gap was not seen for either bonding system.