Magnetic attachments provide valuable clinical advantages due to the specific dynamic characteristics and properties upon comparison conventional mechanical denture retainers. Basic and traditional indications for magnetic attachments have been dental applications in prosthetic location of limited space with non-vital teeth as a radicular intracoronal attachment. Other applications exist and the magnetic attachment can be used in coordination and conjunction with conventional stabilizing retainers such as clasps. The main clinical advantage of the magnetic attachment is simplification of the path of insertion and removal of the denture. However, it will be sacrificed when it is used with other conventional retainers.
The authors have previously proposed an additional application for magnetic attachments. The magnet use as an extracoronal non-visible attachment may be suitable especially in using for vital teeth. After several years of trials and errors, a specific pre-fabricated attachment accessory was developed to facilitate laboratory procedures. The pre-fabricated accessory plastic pattern is designed to form a critical part of the attachment patrix. The pattern is fixed to an abutment crown wax pattern and cast as a single unit. After this, the matrix female portion which is fixed to the denture base is waxed up. Other pre-fabricated pattern accessories such as Housing Dummy, Housing Pattern have also been developed to complete the available scope of components necessary for this technique.
The purpose of this paper is to review and present clinical applications and usage of a new clinical system which utilizes pre-fabricated patterns for a magnetic attachment system. The outline of this new clinical system is introduced and reviewed with several clinical cases.
An educational lecture was done in the 15th The Japanese Society of Magnetic Applications in Dentistry.
I am involved in the research on a magnetic attachment, and related to the transition. Then, it lectured it while presenting the example of clinical according to the history of a magnetic attachment from a clinical standpoint to present.
A magnetic attachment consists of a magnetic assembly and a keeper. In clinical practice, the magnetic assembly is generally fixed in the denture base and the keeper is cast-welded to the metal coping and finally fixed on the abutment. As the basic pattern, the coping is designed as low and flat to liberate detrimental stress to the abutments such as lateral and / or rotational stress. But when the abutment conditions are fairly good, more strict function should be imposed to the magnetic attachment as a reasonable retainer.
After many trials and errors, we have developed a completely new style of application for a magnetic attachment. It is a combination of a magnetic attachment with a cone crown telescope. It was named a “Magnotelescopic Crown : MT Crown”.
Recently, the CAD・CAM system has been introduced into dentistry. Through this system, any kind of material including porcelain and titanium which are inadequate for casting are available for dental works. Although it presently works very well in the production of simple crowns, in the fabrication of specific prostheses such as post crowns and telescopic crowns there were a number of unsolved problems.
By introducing a specific software to the CAD・CAM, we have developed new way to making a rather complicated MT Crown completely automatically. In the present report, we wish to introduce this new method of simplifying the fabrication of a magnetic retainer as a pilot study.
Dental magnetic attachments are widely applied as retainers for dentures, and their utility is acknowledged. However, little is known about the effects of keeper coping designs on the movement of inclined abutment teeth.
In this research, the influence of keeper coping heights on the movement of abutment teeth by using a laser displacement sensor was analysed.Here,we report the result of our investigation.
Magnetic attachments have been used for retaining various prosthetic appliances. It is required therefore to examine not only the statics but also the dynamics on magnetic retention. Simply dynamics of magnetic retention is analyzed by use of a mathematical model considering magnetic force of a magnetic attachment and elasticity of alveolar mucous memberane. As a result, the model has two, one and zero equilibrium solutions depending on the characteristics of the magnetic force and elasticity. Dynamical stability of the solutions is also made clear. The number of the solutions has been analyzed in relation with model parameters. These fundamental properties are considered to be useful for designing especially overdentures using magnetic retention.
Key words: Magnetic attachment, Overdenture, Dynamics
Over 10 years have passed since magnetic attachments have applied clinically, and the problem of retention, magnetic field, and corrosion have been graqdually solved. Recently, these magnetic attachments have being applied as retentive structures of various removable partial dentures.
In this report, we applied this attachment as the extracoronal attachment. Two extracoronal magnetic attachments were applied to a lower partial denture. On the other hand, the magnetic attachment system was included into the pontic region of the upper bridge structure. These treatments improved the esthetic problem of the patient.
Key words: Magnetic attachment, Extracoronal attachment, Removable partial denture
Recently, magnetic attachment has been applied as retentive structures of various removable prostheses.
In this case report, we fabricated a removable partial bridge with a denture plate to the patient who didn’t want to wear a removable partial denture. Magnotelescopic crowns were applied to the abutment teeth. The borme type of occlusal pressure was changed from the tooth- borne type to the tooth-tissue- borne type by adding the denture plate. In made the reduction of the occlusal pressure against the abutment teeth. The denture plate was also encouraged the improvement of easthetic.
A magnotelescopic crown was useful for not only removable partial dentures, but also alternative bridge prostheses.
In this case, these treatments were satisfied with both patient and dentist.
Key words: Magnotelescopoic crown, Removable bridge, Magnetic attachment
The existence of bony prominence if one of the factors which causes difficulty during the removable partial denture treatment planning.
Therefore we employ three modes of treatment plan for such partial denture causes. Namely, the excision of the bony prominence, relieving bony prominence in the design, and avoiding or blocking out the bony prominence in the design.
But while relieving the bony prominence in the design sometimes narrows the intraoral space of mandible.
When a design which avoids the bony prominence is used the width of the major connector becomes narrower of mandibular arch and can compromise the strength.
Therefore we planned to fabricate a partial denture which is held in the undercut by the bony prominence on one side and two magnetic attachments on the other side.
This makes it possible to insert the denture by rotation movement and use the undercut of the bony prominence.
We have obtained good results by using the advantage of the magnetic attachment of the free path of insertion.
Key words: Bony prominence, Magnetic attachment, Overdenture