Retention Performance of Magnetic Attachments on Dental Implants

Retention Performance of Magnetic Attachments on Dental Implants
10 March 2005
A. BOECKLER, C. EHRING, and J.M. SETZ, Martin-Luther-University Halle-Wittenberg, Halle / Saale, Germany
IADR
Objectives: During the past years magnetic attachments (MA) have been established for retention of removable prostheses. Besides the assignments in surgical-prosthodontics MA are more frequently used in implant dentistry. Here MA with different technical constructions are applied. Following the manufacturers' information, recently developed products despite their small size should produce high retention forces. The aim of this study was to verify and to compare the maximum retentive forces and the dynamical development of the draw off forces in contemporary magnetic systems for dental implants. Methods: 12 products of different height and diameter were tested. 3 technical designs were used: dual-systems with open magnetic loops (DO), mono-systems with open (MO) and with closed magnetic loops (MC). From each product 5 specimens were tested in an adjusted and computer navigated pull-testing machine (v=20mm/s, s=40mm). The results (maximum retentive force and dynamic draw off force) were descriptive and statistical analysed (H-/U-Test). The findings were compared with the manufacturers statements. Results: The highest initial retention force was 5.76N. The smallest initial force was measured with 0.67N. In a recently developed and distinctly smaller specimen 5.05N were found. Compared to the manufacturers' information 75% of the specimens showed remarkable lower forces. There were significant differences between the varying attachment designs (pǎ0.05): MC showed the highest and DO the lowest initial retention forces. MO ranged in the middle. At a gap of 0.1mm between the abutment and the denture magnet a complete change of this situation occurred. Afterwards DO and MO showed significantly more retention. Conclusion: In the majority of cases the maximum retention forces were found notable below the manufacturers' figures. There were significant differences between the clinically important draw off forces. These results should be taken into consideration when individually choosing implant-supported magnetic attachments.