Tooth color changes associated with the bracket bonding and debonding / 대한치과교정학회지

The purpose of this study was to evaluate the tooth color changes of resin bonding sites and their adjacent sites on orthodontic bracket bonding. Sixty extracted sound premolars were used and the tooth color was recorded according to the CIE L(*)a(*)b(*) color system using a spectrophotometer. The tooth colors of the twenty premolars were measured and compared before bracket bonding and after removal. On a further twenty premolars, the tooth color was measured before and after only primer application. In the change of L(*) values, according to the bracket bonding and primer application, the lightness was decreased, and in the change of a(*) and b(*) values, the color was changed into a more yellowish color. The color differences (delta E(*)) were calculated from the L(*)a(*)b(*) values and compared with the standard value of clinical detection (delta E(*)=3.7). The color differences between before the bracket bonding and after removal noted exceeded the standard value and those of between before and after the primer application were not larger than the standard value. Toothbrushing was performed after application of the primer to evaluate the color changes according to the primer abrasion. As a control, toothbrushing was performed on the last twenty premolars. The color differences noted were larger than the standard value after toothbrushing. Also, to evaluate the color changes of the tooth which is exposed to sun irradiation after bracket removal, additional photoaging was performed and the color was measured for all teeth. The additional color differences after photoaging were smaller than the standard value. The above results suggest that the tooth color changes after fixed orthodontic treatment.

The Effect of Surface Treatment on Bond Strength of Polycarbonate Bracket / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to evaluate whether the bond strength of polycarbonate brackets can be increased through surface treatment. METHODS: One hundred polycarbonate brackets (Alice) were bonded to bovine incisors with light-cured adhesive. The bracket bases were treated with one of three methods; sandblasting, plastic conditioner application, and combined treatment with sandblasting and plastic conditioner. The brackets without any surface treatment served as the control. The shear bond strength was tested with a universal testing machine, and failure pattern was assessed with the adhesive remnant index. RESULTS: The shear bond strength in all experimental groups was higher than that of the control group (p < 0.001). The group treated with plastic conditioner after sandblasting showed statistically higher shear bond strength than the sandblasting only group (p < 0.05). The group treated with plastic conditioner after sandblasting showed higher shear bond strength than plastic conditioner only group, but the difference was not statistically significant. CONCLUSION: The above results suggest that the surface treatments of polycarbonate bracket is mandatory to improve bond strength, and the most effective method is an application of plastic conditioner after sandblasting.

Effects of Diuretics on Serum and Urinary Electrolytes in Patients with Hypertension

In order to investigate electrolyte changes in serum and urine diuretic therapy, we studied 98 patients with hypertension not optimally controlled by previous treatment. After we divied the patients into three gorups in randomized trial, group A were given Amiloride 10mg/day, group B were given Dihydrochlorothiazide 50mg/day, group C were given Amiloride 5mg/day combined with Dihydrochlorothiazide 25mg/day for 7 days. Blood pressure and electrolyte changes in serum and urine after diuretic theraphy for 7 days were as follows. 1) Serum sodium concentrations were not significantly changed in all three groups(P>0.05). 2) Serum potassium concentrations were increased in group A and C (P<0.05), but there were no significant changes in group B(P<0.05). 3) Urinary sodium exceretions were increased in all three groups(P<0.05). 4) Urinary potassium excretion were decreased in group A and C (P<0.05), but there were increased in group B (P<0.05). 5) Blood pressure were decreased in all three groups(P<0.05).