Effect of hydrofluoric acid-based etchant at an elevated temperature on the bond strength and surface topography of Y-TZP ceramics

OBJECTIVES: This study investigated the effects of a hydrofluoric acid (HA; solution of hydrogen fluoride [HF] in water)-based smart etching (SE) solution at an elevated temperature on yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramics in terms of bond strength and morphological changes.MATERIALS AND METHODS: Eighty sintered Y-TZP specimens were prepared for shear bond strength (SBS) testing. The bonding surface of the Y-TZP specimens was treated with 37% phosphoric acid etching at 20°C–25°C, 4% HA etching at 20°C–25°C, or HA-based SE at 70°C–80°C. In all groups, zirconia primers were applied to the bonding surface of Y-TZP. For each group, 2 types of resin cement (with or without methacryloyloxydecyl dihydrogen phosphate [MDP]) were used. SBS testing was performed. Topographic changes of the etched Y-TZP surface were analyzed using scanning electron microscopy and atomic force microscopy. The results were analyzed and compared using 2-way analysis of variance.RESULTS: Regardless of the type of resin cement, the highest bond strength was measured in the SE group, with significant differences compared to the other groups (p < 0.05). In all groups, MDP-containing resin cement yielded significantly higher bond strength values than MDP-free resin cement (p < 0.05). It was also shown that the Y-TZP surface was etched by the SE solution, causing a large change in the surface topography.CONCLUSIONS: Bond strength significantly improved when a heated HA-based SE solution was applied to the Y-TZP surface, and the etched Y-TZP surface was more irregular and had higher surface roughness.

Changes in Skin Temperature and Sensory Blockade during Spinal Anesthesia / 대한마취과학회지

Twenty otherwise healthy patients, scheduled for elective operations below the knee joints, were allocated to spinal anesthesia with 2 ml 0.5% hyperbaric tetracaine or 2.5 ml 0.5% plain bupivacaine. The levels of sensory blockade(analgesia level to pinprick test) and sympathetic blockade(cephalad level of skin temperature elevation with electronic thermometer) were measured at 5, 10, 20, 30, 60, 90, and l20 minutes after injection of the local anesthetics. The results were as follows: 1) The two groups were well matched for age, height and weight. 2) The decrease in systolic pressure was insignificantly more pronounced in the tetracaine group, and heart rate fell slightly and similarly in both groups. 3) In both groups, the uppermost levels of sensory blockade were T(6~7) about 20 minutes after injection, and their levels were decreased from 30 minutes after injection. 4) In both groups, the uppermost levels of skin temperature elevation were T(5~7) about 20 minutes, insignificantly higher in the tetracaine group, and their levels were decreased from 30 minutes after injection. 5) In both groups, the levels of skin temperature elevation were 1-2 segment higher than those of sensory blockade during onset about 20 minutes, similar at 30 minutes, and lower than those of sensory blockade after l hour following injection,of the local anesthetics. The conclusion of this study is that during spinal anesthesia the relation of the levels of sympathetic and sensory blockade is no difference between induced anesthetic agents, and the time interval following intrathecal injection is important factor in their relationship.

Changes in Skin Temperature and Sensory Blockade during Spinal Anesthesia / 대한마취과학회지

Twenty otherwise healthy patients, scheduled for elective operations below the knee joints, were allocated to spinal anesthesia with 2 ml 0.5% hyperbaric tetracaine or 2.5 ml 0.5% plain bupivacaine. The levels of sensory blockade(analgesia level to pinprick test) and sympathetic blockade(cephalad level of skin temperature elevation with electronic thermometer) were measured at 5, 10, 20, 30, 60, 90, and l20 minutes after injection of the local anesthetics. The results were as follows: 1) The two groups were well matched for age, height and weight. 2) The decrease in systolic pressure was insignificantly more pronounced in the tetracaine group, and heart rate fell slightly and similarly in both groups. 3) In both groups, the uppermost levels of sensory blockade were T(6~7) about 20 minutes after injection, and their levels were decreased from 30 minutes after injection. 4) In both groups, the uppermost levels of skin temperature elevation were T(5~7) about 20 minutes, insignificantly higher in the tetracaine group, and their levels were decreased from 30 minutes after injection. 5) In both groups, the levels of skin temperature elevation were 1-2 segment higher than those of sensory blockade during onset about 20 minutes, similar at 30 minutes, and lower than those of sensory blockade after l hour following injection,of the local anesthetics. The conclusion of this study is that during spinal anesthesia the relation of the levels of sympathetic and sensory blockade is no difference between induced anesthetic agents, and the time interval following intrathecal injection is important factor in their relationship.