Effects of calcium hydroxide on physical and sealing properties of canal sealers.

AIM: To investigate whether Ca(OH)2 in four different agents alters the physical properties (Exp. I) and sealing ability (Exp. II) of root canal sealers. EXPERIMENT: (Exp. I) Calcipex (Nippon Sika-Yakuhin, Shimonoseki, Japan), Vitapex (Neo-Dental, Tokyo, Japan), Calkyl (Showa Yakuhin, Tokyo, Japan), and Ca(OH)2 were used as Ca(OH)2 agents. Four sealers were tested for flow, working time, setting time, and film thickness: Canals (Showa Yakuhin), Canals-N (Showa Yakuhin), Ketac -Endo (Espe, Seefeld, Germany), and Sealapex (Kerr, Romulus, MI, USA). Each Ca(OH)2 agent was added to 10 vol.% of each sealer, and the mixture and controls without a Ca(OH)2 agent were tested according to ISO specifications. Measurements were compared using Student's t-tests (P < 0.05). (Exp. II) After removing Ca(OH)2 agents applied to the root canals of 100 extracted human teeth, canals were filled with sealer. Controls were filled with each sealer without Ca(OH)2 agents. Sealing ability was evaluated using distance of dye penetration from the apices. Dye penetration data were compared using analysis of variance and post hoc Newman-Keuls test (P < 0.05). RESULTS: Ca(OH)2 agents influenced the physical properties of the sealers. Flow and setting time met ISO requirements, but film thickness and working time did not. Apical sealing ability of all four sealers was influenced by Ca(OH)2 agents. The sealing ability of Sealapex improved with all Ca(OH)2 agents. The physical and sealing abilities varied among the other sealers. CONCLUSIONS: Contact with Ca(OH)2 agents left on the canal wall caused considerable changes to the sealing ability of sealers.

Effects of endodontic instrument handle diameter on electromyographic activity of forearm and hand muscles.

AIM: To determine the influence of the handle diameter of endodontic instruments on forearm and hand muscle activity using electromyographic (EMG) recording. METHODOLOGY: Size 45 K-type files were fitted with four different handle diameters; 3.5, 4.0, 5.0, and 6.0 mm. Seven dentists then attempted to negotiate to the working length acrylic resin root canals with each of the four handle sizes using a reaming motion. EMG activities were recorded from the flexor pollicis brevis muscle (f.p.b.), the flexor carpi radialis muscle (f.c.r.), and the brachioradialis muscle (b) with bipolar surface electrodes. The time taken to negotiate the canals, the area of integrated EMG that corresponded to the amount of EMG activity required during penetration and the maximum amplitude of EMG were measured using the EMG data. Results were analysed statistically using a one-way factorial ANOVA test and multiple comparison tests. RESULTS: Reaming time and integrated EMG area of each muscle decreased with an increase in handle diameter. The most significant difference in time and area of integrated EMG was detected between handles of 6 mm and 3.5 mm diameter (time: P < 0.01, area of the f.p.b.: P < 0.01, area of the f.c.r. and b: P < 0.05), and between handles of 5 mm and 3.5 mm diameter (P < 0.05). Both 5 mm and 6 mm handles significantly decreased the maximum amplitude of EMG recorded from the f.p.b. compared with 3.5 mm handles (between 3.5 mm and 6 mm: P < 0.01, between 3.5 mm and 5 mm: P < 0.05). CONCLUSION: The results indicate that handle diameter has an effect on reaming time as well as on muscle activity. As a consequence, handle diameter influenced operator performance during instrumentation.

Nasal administration of salmon calcitonin for prevention of glucocorticoid-induced osteoporosis in children with nephrosis.

To determine the effect of intranasal administration of salmon calcitonin on glucocorticoid-induced osteoporosis in children with nephrosis, we gave 100 U of calcitonin intranasally on alternate days with 1 alpha-hydroxyvitamin D3 to five children, 8 to 12 years of age, with frequently relapsing nephrosis. Four patients with osteoporosis, 10 to 14 years of age, were treated only with 1 alpha-hydroxyvitamin D3 and served as control subjects. Both groups were treated with an almost equal amount of glucocorticoids previously and during this study period. Bone mineral content of the spine was measured by a quantitative computed tomographic technique. The bone mineral content was preserved in both cortical and spongeous areas of the vertebrae during the 16-month period in the calcitonin-treated group but was decreased significantly in the control group. Urinary hydroxyproline and calcium excretion decreased significantly in the calcitonin-treated group. The serum calcium and phosphorus concentrations and the parathyroid function did not change significantly in either group. We conclude that calcitonin suppressed bone resorption and might be useful for the long-term treatment of osteoporosis, in combination with 1 alpha-hydroxyvitamin D3, in children with nephrosis requiring long-term glucocorticoid therapy.