Troubleshooting
PRINCIPALS OF MAGNETIC ATTACHMENT
The magnetic attachment is retentive attachment for removable prostheses which assist retention using magnetic force.
The magnetic assembly contains the magnet inside and is set in denture base. The keeper is magnetically attracted to the magnetic assembly and is attached to the tooth root. Additional retention of the prosthesis is thus provided by the attraction between the magnet in the denture and the keeper on the root face. (Fig1-1a)
The features of the magnetic attractive force are as follows.
- Constant retentive force. The retentive force is not decreased over time beacuse the material charactristic of the permanent magnet is used.
- Attractive force acts primarily in the vertical direction at right angles to the attractive fave of magnet. The magnetic cuopling thus become easily dissociated by any harmful lateral and rolling forces and so reduces lateral loading of the tooth root.
- Retention after slight disengagement of the magnet and keeper. Here retention principals are different from conventional mechanical retainers which rely on frictional forces for retention. The magnetic attachment tends to maintain the retention and attempt to restore the relationship between the magnet and the keeper even when physically separated by a small disctance. However, if the distance becomes more than 0.05 mm, the retentive force is decreased rapidly. (Fig1-1c)
Fig 1-1a Principal of magnetic attachment. the attractive force between the magnetic assembly inside the denture and the keeper inside the root cap producesa a retentive force.
Fig 1-1b The retentive force after repeat engagement and disengagement of various retainers. Only magnetic attachment maintains their retentive force.
Fig 1-1c The relationship between air gap and retentive force of the magnetic attachment.
