Dentistry – Prosthodontics – Holding or positioning denture in mouth
Reexamination Certificate
1999-07-22
2003-04-01
Lucchesi, Nicholas D. (Department: 3732)
Dentistry
Prosthodontics
Holding or positioning denture in mouth
Reexamination Certificate
active
06540515
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a dental attachment, a dental keeper, a dental magnet and a method for taking an impression using thereof, and more particularly, to a dental attachment used for dental prostheses such as a denture, a crown and a crown-and-bridge set, and a dental keeper of the dental attachment which use magnetic force for retention and a method for taking an impression using thereof.
2. Description of the Related Art
Various methods have been used for retaining a dental prosthesis such as a denture, a crown and a crown-and-bridge set in medicine and dentistry. For instance, methods which use a mechanical attachment used to be among the main methods for the purpose. These days, however, a magnetic attachment (also called as a magnetic retention, a magnetic system, a magnetic anchor attachment, rare earth attachment and so on) utilizing a potent magnet of small size has been developed and applied clinically.
In general, a magnetic attachment is comprised of a magnetic assembly, which is provided with a dental prosthesis, and a dental keeper made of a steel plate (usually a stainless steel plate), which may be attached to an abutment. Thus, the dental keeper is attracted to the magnetic assembly by the magnetic force and the denture prosthesis is attached to the abutment.
FIG.1
is a diagram for explaining an example of a conventional dental prosthesis (denture) using a magnetic attachment. The dental prosthesis
155
includes a denture portion comprising a magnet
152
, a resin base
156
and an artificial tooth
157
, and a dental keeper
151
formed integrally with a root cap
153
. The numeral
158
indicates gingival tissues and the numeral
159
indicates a root of a tooth. The dental keeper
151
, which is made of a magnetic stainless steel (or magnetic metal), is embedded in the upper portion of the root cap
153
so that the denture portion is fixed to the root cap
153
through the magnetic force of the magnet
152
.
The above-mentioned magnetic attachment has advantages in that an excessive stress on the abutments at the time of insertion and removal of a dental prosthesis may be eliminated, unlike the mechanical attachments, and the insertion/removal operation of the dental prosthesis itself is very easy. Also, the degree of the holding force of the magnet used may be measured and it is not attenuated during a long-term use. Moreover, the magnetic attachments are non-directional for the insertion and removal of dental prostheses and they transmit little lateral force to the abutments.
However, when the magnetic assembly and the dental keeper are positioned at their respective locations manually, it is difficult to exactly position them at a desired location, and it requires a skillful hand for carrying out the operation. Also, since the dental keeper is embedded in the upper portion of the root cap, it is difficult to adjust the position of the dental keeper when a shift in location of the dental keeper has occurred. Moreover, there have been reports of accidents in which dental prostheses were faultily detached due to an instable attachment of the dental keeper and the magnetic assembly.
On the other hand, it has been proposed to make the dental keeper of a magnetic attachment removable since there is a danger that the magnetic attachment has an effect on biological measurements which utilize a magnetic force such as MRI. However, the proposed method is a method in which the dental keeper is embedded completely in the root cap. Therefore, according to the above method, the size of the dental keeper must be reduced since there is additional space needed for a metal part which is used for covering the dental keeper. Hence, it is likely that the operation according to the above method becomes tedious and complicated.
SUMMARY OF THE INVENTION
Accordingly, it is a general object of this invention to provide a magnetic attachment used for retaining a dental prosthesis in which the above mentioned problems are eliminated.
A more specific object of the present invention is to provide a magnetic attachment used for retaining a dental prosthesis by which a dental prosthesis having a magnetic assembly (i.e., female part of magnetic attachment) may be firmly attached to a dental keeper (i.e., male part of magnetic attachment) removably fixed to an abutment.
Another object of the present invention is to provide a magnetic assembly (i.e., female part of magnetic attachment) and a dental keeper (i.e., male part of magnetic attachment) which are appropriate for use in the above magnetic attachment.
Yet another object of the present invention is to provide an intermediate metal which may be used for fixing the dental keeper to a natural tooth.
Yet another object of the present invention is to provide a magnetic attachment which may be used for a method for taking an impression in dentistry.
The objects described above are achieved by a magnetic attachment used for retaining a dental prosthesis, comprising a male part which may be fixed to an abutment and a female part which may be fixed to the dental prosthesis, wherein the male part includes a head portion which may be attached to the female part and a fixing member used for fixing the male part to the abutment, and the female part includes a cap portion having a cover portion for covering the male part.
According to the above magnetic attachment, since the male part may be firmly covered by the cover portion of the cap portion, the attachment of the male part and the female part of the magnetic attachment can be accurately made.
The objects described above are also achieved by the magnetic attachment, wherein the fixing member is detachable from the male part.
According to the above magnetic attachment, since the fixing member is detachable from the male part, a male part having an irregular shape and not easily rotated may be used in accordance with the condition of an abutment.
The objects described above are also achieved by the magnetic attachment, wherein a magnet is included in one of the male part, the female part, and the male part and the female part.
According to the above magnetic attachment, since the magnet may be located in the male part, the female part or both, the range of the application of the magnetic attachment may be widened and, for instance, a female part including a larger magnet in size having an increased magnetic force may be used for a case in which there is not much clearance present. Also, since it becomes possible to directly cast a crown and a bridge to a female part, the precision of attachment may be improved.
The objects described above are also achieved by the magnetic attachment, wherein the male part is removable from the abutment.
According to the above magnetic attachment, since the male part is removable from the abutment, a danger that the magnetic attachment may effect the result of a biological measurement which utilizes a magnetic force such as MRI can be avoided.
The objects described above are achieved by a male part of a magnetic attachment used in dentistry, wherein the male part includes a head portion and a fixing member which is used for fixing the male part to an abutment, the head portion, when fixed, being projected from the upper surface of the abutment, and the male part may be used singly without being in combination with a female part of magnetic attachment.
According to the above male part of magnetic attachment, since the head portion of the male part is projected from the upper surface of the abutment when it is fixed, it is easy to cover the head portion with the female part, and hence an attachment of the male part and the female part may be carried out accurately.
The objects described above are also achieved by the male part of magnetic attachment, wherein the male part comprises one of a magnet, a magnetic metal, and a magnet and a magnetic metal.
According to the above male part of magnetic attachment, since the male part may include, unlike a conventional male part, either a magnet
Andrus Sceales Starke & Sawall LLP
Lucchesi Nicholas D.
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