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PubMed2001

In vitro assessment of the mechanical properties of latex and non-latex orthodontic elastics.

The increased incidence of latex allergies has led to the development of non-latex orthodontic products. The purpose of this study was to compare the mechanical properties of latex and non-latex orthodontic elastics. The elastics tested were from 2 manufacturers (GAC and Masel) and made of 2 materials (latex and non-latex). The properties tested included cross-sectional area, breaking force, peak load, peak stress, stiffness, modulus, hysteresis, and 24-hour load relaxation. The data were analyzed with 1-sample t tests, an analysis of variance, and the Fisher PLSD test. Between GAC and Masel, the GAC non-latex elastics had greater breaking forces than did the Masel non-latex elastics. The Masel latex elastics had greater breaking forces than did the Masel non-latex elastics. The GAC non-latex elastics showed more viscoelastic properties than both the GAC latex elastics and the Masel non-latex elastics; however, the Masel elastics were more viscoelastic than the GAC elastics. Forces generated by the elastics decreased over 24 hours to an average load approximating 75% of the manufacturers' values (GAC latex, Masel latex, and Masel non-latex elastics) and to 60% for the GAC non-latex elastics. The mechanical properties of the non-latex elastics were not comparable to those of the latex elastics. Therefore, the clinical choice of elastics should be based on the patient's medical history and the specific mechanical properties of the type of elastic.

Analysis of Variance↗
PubMed2004

Hemorrhoidal elastic band ligation with flexible videoendoscopes: a prospective, randomized comparison with the conventional technique that uses rigid proctoscopes.

BACKGROUND: Elastic band ligation by means of a rigid proctoscope is the treatment of choice for patients with symptoms caused by internal hemorrhoids of grade 2 to 3. In contrast to the flexible videoendoscope, the rigid proctoscope has limited maneuverability, has a narrower field of view, and does not allow adequate documentation. Therefore, a randomized trial was conducted to compare the safety and the efficacy of conventional elastic band ligation with videoendoscopic elastic band ligation. METHODS: A total of 100 consecutive patients (mean age 47 [12] years) with chronically bleeding grade 2 or 3 internal hemorrhoids were randomized to elastic band ligation or videoendoscopic elastic band ligation. For videoendoscopic elastic band ligation, a reusable multiband ligator was attached to the end of a therapeutic upper videoendoscope. From one to 3 bands were placed per session in both groups. Re-treatment was performed every 2 to 3 weeks in both groups until cessation of bleeding and eradication of the hemorrhoids (at least grade 2) were achieved. Thereafter, the patients were followed to assess complications and efficacy. Recurrent bleeding was considered a treatment failure. RESULTS: To achieve the desired therapeutic aims, a significantly lower number of treatment sessions was required in the videoendoscopic elastic band ligation group (1.8 [0.8] vs. 2.4 [0.9]; p < 0.01) and the total number of bands applied was significantly less (2.8 [1.1] vs. 3.7 [1.4]; p < 0.01). Pain was noted after ligation by 25% of patients in the elastic band ligation group compared with 27% of those who had videoendoscopic elastic band ligation. However, analgesic medications were required in only 7% after elastic band ligation and 9% after videoendoscopic elastic band ligation (NS). Post-ligation bleeding that had to be treated endoscopically occurred in 3.5% of the patients of the elastic band ligation group and 3.2% of those in the videoendoscopic elastic band ligation group (NS). Blood transfusion was not required. At a median follow-up of 12 months, there was no recurrence of bleeding in 40 patients (80%) in the conventional elastic band ligation group vs. 43 (86%) in the videoendoscopic elastic band ligation (NS). CONCLUSIONS: The long-term efficacy and safety of conventional elastic band ligation and videoendoscopic elastic band ligation are highly comparable. However, when videoendoscopic elastic band ligation is performed, significantly fewer treatment sessions are required.

Endoscopes, Gastrointestinal↗