Retentive force and magnetic flux leakage of magnetic attachment in various keeper and magnetic assembly combinations.

摘要

STATEMENT OF PROBLEM: Magnetic attachments are commonly used for overdentures. However, it can be difficult to identify and provide the same type and size of magnetic assembly and keeper if a repair becomes necessary. Therefore, the size and type may not match. PURPOSE: This study evaluated the retentive force and magnetic flux strength and leakage of magnetic attachments in different combinations of keepers and magnetic assemblies. MATERIAL AND METHODS: For 6 magnet-keeper combinations using 4 sizes of magnets (GIGAUSS D400, D600, D800, and D1000) (n=5), retentive force was measured 5 times at a crosshead speed of 5 mm/min in a universal testing machine. Magnetic flux strength was measured using a Hall Effect Gaussmeter. Data were statistically analyzed using a 1-way ANOVA, and between-group differences were analyzed with Tukey's HSD post hoc test (alpha=.05). RESULTS: The mean retentive force of the same-size magnet-keeper combinations was 3.2 N for GIGAUSS D400 and 5.1 N for GIGAUSS D600, but was significantly reduced when using larger magnets (P<.05). Magnetic flux leakage was significantly lower for corresponding size combinations. CONCLUSIONS: Size differences influence the retentive force and magnetic flux strength of magnetic attachments. Retentive force decreased due to the closed field structure becoming incomplete and due to magnetic field leakage.