CA1069355A - Dental dowel pin unit and method using same - Google Patents
Dental dowel pin unit and method using sameInfo
- Publication number
- CA1069355A CA1069355A CA000270246A CA270246A CA1069355A CA 1069355 A CA1069355 A CA 1069355A CA 000270246 A CA000270246 A CA 000270246A CA 270246 A CA270246 A CA 270246A CA 1069355 A CA1069355 A CA 1069355A
- Authority
- CA
- Canada
- Prior art keywords
- jacket
- die
- dowel pin
- pin
- floater
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
- A61C9/00—Impression cups, i.e. impression trays; Impression methods
- A61C9/002—Means or methods for correctly replacing a dental model, e.g. dowel pins; Dowel pin positioning means or methods
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- Health & Medical Sciences (AREA)
- Oral & Maxillofacial Surgery (AREA)
- Dentistry (AREA)
- Epidemiology (AREA)
- Life Sciences & Earth Sciences (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Dental Prosthetics (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
This invention provides an improved dental dowel pin unit in which a dowel pin to be embedded in a tooth die is encased in a jacket and provided with a flat planar floater designed to rest on the surface of the die stone material. The jacket portion embedded in the base material provides a tough resilient socket in which the dowel pin can be re-inserted and removed repeatedly for maintaining a precise positioning of the die. The apparatus provides an improved method for preparing die models.
This invention provides an improved dental dowel pin unit in which a dowel pin to be embedded in a tooth die is encased in a jacket and provided with a flat planar floater designed to rest on the surface of the die stone material. The jacket portion embedded in the base material provides a tough resilient socket in which the dowel pin can be re-inserted and removed repeatedly for maintaining a precise positioning of the die. The apparatus provides an improved method for preparing die models.
Description
:~0693S5 This invention relates to improved apparatus and methods for making dental prosthetic devices. In particular, it relates to an improved design for a dental dowel pin unit and an improved method, using this apparatus, for preparing dies of patient's teeth.
Conventional dental techniques for the making of dental crowns, inlays, bridges and prosthetic devices of this nature usually involve making a model of the patientls mouth, or at least the teeth and gums in that region of the mouth requiring the repair work. Such models are usually made by preparing a tray containing a mouldable malleable material (hereinafter referred to as impression material3 which is then pressed on to the teeth and gums in the patient's mouth so as to ~orm a female impression thereof in the impression material. By pouring a hardenable matexial, commonly ~eferred to as die stone, into this female impression, an exact reproduction of the shape of the patient's teeth and gums is formed.
A dental technician then has an exact model of the patient's teéth on which to do whatever technical work is needed to effect repairs or prepare prosthetic devices. The technician's work commonly requires that the individual tooth die be separated so that they can be worked on individually and therefore techniques have been devised by which the model of the patient's mouth can be cut into individual tooth dies~ This, however, requires some manner by which they can be replaced in their proper orientation and position in the model. The technique commonly used is to insert a dowel pin at approximately the central axis of each individual tooth when the die stone is hardening leaving the top part of the dowel pin protruding from the die stone. Later a second material, generally known as the base material which is commonly a plaster or some ~o693s5 such similar material, is poured over the die stone to cover the protruding ends of the dowel pins. Thus when the individual tooth segments are cut away and removed, they have protruding therefrom a dowel pin which can be replaced in a corresponding recess in the base material to reposition and orient the tooth in its original relationship to other parts of the model.
Past experience has found difficulties with this technique since constant removal and replacement creates wear on the dowel pin or its recess in the base material which eventually creates a loose and inadequate positioning of the tooth model. Dirt and dust in the base recess will often affect the repositioning. Furthermore, the positioning of the dowel pins in the die stone often creates difficulty since it is highly desirable that the dowel pins be substantially centered on the vertical axis of the tooth models and that the pins be oriented substantially parallel to each other so as to allow the individual tooth dies to be separated and removed from the mouth model. Manual placement of the dowel pins is considered a clumsy, inexact and painstaking method. Other techniques in which the dowel pins are positioned by support structures attached to the edges of the impression material have been found to be similarly inefficient and imprecise, partly because the contours of the impression are so irregular.
It is the purpose of this invention to provide an apparatus and method for production of dental models in which dowel pins can be simply and efficiently placed so as to provide a firm and precise replacement and orientation of the individual tooth dies.
I have found that dental procedures of this nature are improved by use of a dowel pin unit of my invention and an improved method employing this apparatus. I have accordingly conceived a lo~s3ss dowel pin unit for use in maXing dental models comprising a dowel pin having a tapered longitudinal section wider at the lower end and narrower at the top end, and having asym.~etrical cross-section.
The dowel pin is enclosed in a jacket of plastic, or some such material, ribbed on its outer surfa~e to form a structural bonding with the surrounding die stone or base material, as the case may be~
At about middle of the dowel pin unit is a flat planar floater member extending outwardly from the jacket approximately perpendicular to the axis of the pin. The lower end of the pin is structurally fixed within the jacket by an engaging notch and lug assembly and the upper end of the pin is removably held within the jacket by an engageable ball and socket assembly. The foregoing apparatus allows a dental technician to employ the following method.
Having a female impression o~ the patient's mouth, the technician may then fill the impression with die stone material and insert the lower end of a pin unit, as described above, into the individual tooth model while the die stone is soft using the floater to position the pin unit in proper location and orientatio~
the floater being adapted to rest at the surface of the die stone material. When the die stone material has hardene~, the upper end of the pin unit will be protrudin~ and this can be embedded in a base material by pouring the base material on top of the die stone, this latter'step being taken after the jacket surround-ing the pin has been severed or weakened just above the floater.
When the base hardens the individual tooth die can be separated by cutting the die stone material on either side of the tooth die and the tooth die can be removed by pulling the tapered dowel pin out of the portion of the jacket embedded in'~the base (by overcoming the resistance of the ball and socket). The lower end of the jacket will, of course, remain embedded in the base material and provide ~ID~;9;~55 a firm resilient and precise socket into which the dowel pin can be re-inserted to replace the tooth die in its proper position and orientation.
A better understanding of the improved apparatus can be gleaned from a detailed description of one embodiment with reference to the enclosed drawings in which:
Figure 1 is a vertical cross-section of a tray containing an impression of a tooth filled with die stone material incorporating a dowel pin unit of the present invention;
Figure 2 is a horizontal cross-section of a dowel pin unit in accordance with this invention;
and Figure 3 illustrates a typical model of a patient's mouth showing a removable tooth die.
The cross-section of Figure 1 illustrates a stage in the making of a dental model using my improved dowel pin unit.
The tray 2 holds a quantity of impression material 4 which has been pressed over the appropriate portion o~ a patient's mouth to form a female impression of the patient's tooth (or teeth) and gums as represented by the impression profile 6, the lower end of which at 8 represents the configuration of the patientls tooth, while the upper portion represents the configuration of the gums at the base o~ the teeth.
Thus the technician is provided with an exact negative reproduction of the shape of the relevant portion of the patient's mouth, especially the teeth involved.
In order to perform the necessary prosthetic work, the technician will produce an exact model of the patient's teeth and gums by filling the negative impression with a fluid (but hardenable) material 10 known as die stone which, upon harden-ing, will produce a tough resilient model of the patient's teeth on which the technician can work.
Since the technician will want to work on an individual tooth die, it is desirable to separate the individual die from the rest of the model of the mouth and frequently during his work will want to remove and replace the tooth to its original position and orientation with respect to the rest of the model. To facili~ate this, the model is provided with one or more dowel pins such as illustrated at 12, the lower end of which is embedded in th~ die stone of the tooth and the upper half of which protrudes above the die stone where it is later embedded in a base material 14 which is poured over the die stone when the latter has hardened.
Conventionally, a dowel pin of previous design would be inserted either before the die stone was poured into the impression or after pouring but before the die stone had hardened.
Previous techniques for positioning dowel pins involved wire or other supporting devices which could be struck into the sides of the impression material or otherwise supported on the impression or tray to maintain the dowel pin in position while the die stone hardened. In the past, repeated removal and replacement of the individual tooth die, by withdrawing the dowel pin from its location in the base material and replacement thereof r developed inaccuracies because of wearing of the base material or the dowel pin itself or the inclusion of dirt or dust from the sides of the base material and other foreign material in the dowel pin recess in the ba~e~ For instance fine particles resulting from the wear on constant replacement and removal of the dowel pin would cause material to build up in the recess of the base material preventing proper snug ;9355 replacement of the dowel pin.
Figure 1 illustrates an improved design for a dowel pin unit in which the dowel pin 12 is encased in a jacket 16 of suitable material such as plastic, which has a series of ridges 18 (or other similar irregularities) about its outer surface so as to provide a firm structural bond with the surrounding die stone or base material in which it is encased.
Located approximately mi~way along the dowel pin unit and extending outwardly from the outer surface of the jacket is a floater 20 which is a flat horizontal planar element surrounding and extending out from the jacket 16 and adapted to lie, as illustrated in Figure 1, along the upper surface of the die stone material. In the usual case, as illustrated in Figure 1, this floater is positioned perpendicular to the long axis of the dowel pin but in certain cases might be set at an angle less than 90 thereto ~epending on the t~pe of model and the work being performed thereon.
~ ocated in the lower half of the dowel pin 12 is a notch 22, which may or may not extend around the entire circumference of the pin, and a corresponding lug 24 on the inner surface of the jacket located and dimensioned so as to engage snugly in the notch 22. This provides a firm tight engagement and structural bond between the lower end of the dowel pin and the jacket surrounding it. In the upper portion of the dowel pin is a pair of sockets 26 in the form of indentations in-the wall of the pin in a generally curved configuration of approximately the shape of a portion of a sphere. Correspondingly the jacket at the same location has on its inner surface a projecting ball portion 28 which engages snugly into the corresponding socket 26.
As can be seen in Figure 1, the dowel pin and its jacket are generally tapered from a wider portion embedded in the die stone to a narrower portion in the base material so as to facilitate removal of the pin from the base material when the technician is working on the model.
Figure 2 illustrates a corss-sectional view of the dowel pin unit including the dowel pin 12, the surrounding jacket 16 and the sockets 26. The cross-sectional shape illustrated and considered desirable is approximately a sector shape having two straight sides subtenaed by a curved third side. This configuration allows for easy replacement of the dowel pin within its recess in the proper orientation and avoids the possibility of error in replacing it in the wrong orientation.
The dowel pin also has an anchor 30 which is dove-tailed in cross-section so as to anchor the pin firmly in the die stone matçrial surrounding it.
The top end of the jacket covering the top end of the dowel pin is substantially thinner, almost in the nature of a membran~,--at 32-to allow for access to the top of the dowel pin for purposes described later.
Thus with the use of this dowel pin unit, a technician having an impression provided by known methods somewhat in the nature of that illustrated in Figure 1, can proceed to fill the impression with die stone material to approximately the level illustrated, place the model on a vibrator to remove voids and --level the fluid die stone, and then while the die stone is still soft, position a dowel pin unit as illustrated approximately co-axial with each individual tooth impression, inserting the broad end of the pin until the floater 20 rests along the top surface of the die stone material, as seen in Figure 1.
, ~0~935S
Although the eLement 20 i9 re~erred to as a floater it should be understood that it9 function does not depend purely on floatation in the sense that it provides buoyancy by virtue of its lighter specific gravity. To a large extent it may function by virtue of its broad area combined with the thick viscosity of the die stone fluid to maintain the orientation of the dowel pin unit.
The die stone material is then allowed to harden to substantial firmness thereby firmly embedding the lower end of the dowel pin unit therein.
After the die stone has hardened, the jacket of the dowel pin unit (being of plastic or other such material) can be severed around the circumference oX the pin at approximately the level of the top of the floater 20 so as to allow separation of the upper and lower halves of the jacket at a later stage in the pxocedure. Alternatively, the dowel pin unit might be fabricated with an indentation or weakness around its circumference just above the level of the floater which would allow separation of the two halves by exerting sufficient force.
A base is then formed by pouring base material 14 (plaster or some such similar material) on top of the die stone so as to substantially encase the upper end of the dowel pin and jacket. The tip of the dowel pin unit may be allowed to protrude from the top of the base although this is not necessary.
In accordance with conventional practice, it is preferable to coat the upper surface of the die stone material with a non-adhesive material to form a "separation coating" so that in subsequent operation the die stone material may be lifted and separated from the base material.
~L0693S5 When the die stone and base material are hardened, tray 2 and impression material 4 can be removed leaving a model of the patient's teeth, such as seen in Figure 3.
In order to remove a single tooth die a vertical cut is made on each side of the tooth, as at 34 and 36 respectively, in Figure 3, which cuts penetrate down to the line of interface between the die stone and the base m~terial. Because of the non-adhesive layer between those two materials they will separate at the plane of contact. By exercising some force the tooth die may be removed by pulling it out of the base with sufficient force to pull the narrow upper end of the dowel pin 12 out of its jacket, overcoming the resistance of the ball and socket engagement.
Thus the individual tooth 8 with its attached dowel pin 12 is available for further work by the technician. The individual tooth die may then be replaced in the model by re-inserting the end of the dowel pin 12 into the end of the jacket which remains embedded in the base material, as-seen at 38 in Figure 3.
This e~bedded portion of the jacket provides a tough I resilient-recess which-will be léss subjec-t-to-wear from numerous- - -I~ 20 movements of the tooth die. ~ecuase of the asymmetric (by which is meant it does not have an axis of symmetry though it may be - symmetrical about a chosen plane) cross-section the pin can only be inserted in one orientation. Furthermore, because of the ball and socket engagement the individual tooth member can be held firmly in the base material without accidentally falling out.
As shown in Figure 1, the narrow end of the dowel pin and jacket can be left protruding from the base material but if it is not, the base material may be ground down until the upper end is exposed. A small punch or other rod-lik~ instrument can be placed against the narrow end of-t~e dowel pin 12 and tapped so a~ to _ g _ lO~;9;~S5 assist disengaging the dowel pin from its jacket to remove the individual tooth model.
An a~ditional advantage to this invention may be achieved by using dowel pin units having a jacket of different colours of plastic. This would facilitate matching individual tooth dies back into their respective position by co-ordinating the colour of the floater and the other saparated part of the jacket embedded in the base material.
It may also be considered desirable to further anchor the floater to the die stone material by dove-tailed protrusions on the undeside of the floater, such as seen at 40 in Figure 1.
Although the notch and-lug 22 and 24 are shown substantially spaced from the level of the floater, they might be located closer to that mid point, as might the ball and socket assembly-26 and 28,- as may be dictated by design considerations.
Thus a dowel pin unit, as disclosed, can be used after the die;~stone material has been poured in liquid form into the impression,-is=vibrated-and begins to harden. The broad end of the dowel pin is inserted into the die stone down to the point where the floater rests on the upper surface of the die stone - material. The viscosity or thickness of the die stone material as it is hardening combined with the broad area of the floater will tend to keep the dowel pin unit in its upright position approx-imately coincident with the vertical axis of the individual tooth.
Where several such pins are inserted, they will tend to be substantially parallel which is important to facilitate removal of the dies and other work by the dental technician. Unlike previous methods, it is not so dependent on the technician being able to estimate the parallelism o~ the pins nor is the position ~L0~93SS
of the pin dependent on some auxiliary supporting device resting on the generally irregular outline of the impression mould.
Although a variety of materials might be used, it is considered advantageous that the pin be a strong material such as metal although it might be a strong plastic, and the jacket a firm, resilient, but not hard, plastic material. Since the lower end of the pin will be withdrawn from the lower end of the jacket it is desirable that the two materials be chosen or otherwise adapted to permit easy parting during the processes described above.
Various modifications and variations to the fore-going structure and method could be improvised without departing from the inventive concept herein.
Conventional dental techniques for the making of dental crowns, inlays, bridges and prosthetic devices of this nature usually involve making a model of the patientls mouth, or at least the teeth and gums in that region of the mouth requiring the repair work. Such models are usually made by preparing a tray containing a mouldable malleable material (hereinafter referred to as impression material3 which is then pressed on to the teeth and gums in the patient's mouth so as to ~orm a female impression thereof in the impression material. By pouring a hardenable matexial, commonly ~eferred to as die stone, into this female impression, an exact reproduction of the shape of the patient's teeth and gums is formed.
A dental technician then has an exact model of the patient's teéth on which to do whatever technical work is needed to effect repairs or prepare prosthetic devices. The technician's work commonly requires that the individual tooth die be separated so that they can be worked on individually and therefore techniques have been devised by which the model of the patient's mouth can be cut into individual tooth dies~ This, however, requires some manner by which they can be replaced in their proper orientation and position in the model. The technique commonly used is to insert a dowel pin at approximately the central axis of each individual tooth when the die stone is hardening leaving the top part of the dowel pin protruding from the die stone. Later a second material, generally known as the base material which is commonly a plaster or some ~o693s5 such similar material, is poured over the die stone to cover the protruding ends of the dowel pins. Thus when the individual tooth segments are cut away and removed, they have protruding therefrom a dowel pin which can be replaced in a corresponding recess in the base material to reposition and orient the tooth in its original relationship to other parts of the model.
Past experience has found difficulties with this technique since constant removal and replacement creates wear on the dowel pin or its recess in the base material which eventually creates a loose and inadequate positioning of the tooth model. Dirt and dust in the base recess will often affect the repositioning. Furthermore, the positioning of the dowel pins in the die stone often creates difficulty since it is highly desirable that the dowel pins be substantially centered on the vertical axis of the tooth models and that the pins be oriented substantially parallel to each other so as to allow the individual tooth dies to be separated and removed from the mouth model. Manual placement of the dowel pins is considered a clumsy, inexact and painstaking method. Other techniques in which the dowel pins are positioned by support structures attached to the edges of the impression material have been found to be similarly inefficient and imprecise, partly because the contours of the impression are so irregular.
It is the purpose of this invention to provide an apparatus and method for production of dental models in which dowel pins can be simply and efficiently placed so as to provide a firm and precise replacement and orientation of the individual tooth dies.
I have found that dental procedures of this nature are improved by use of a dowel pin unit of my invention and an improved method employing this apparatus. I have accordingly conceived a lo~s3ss dowel pin unit for use in maXing dental models comprising a dowel pin having a tapered longitudinal section wider at the lower end and narrower at the top end, and having asym.~etrical cross-section.
The dowel pin is enclosed in a jacket of plastic, or some such material, ribbed on its outer surfa~e to form a structural bonding with the surrounding die stone or base material, as the case may be~
At about middle of the dowel pin unit is a flat planar floater member extending outwardly from the jacket approximately perpendicular to the axis of the pin. The lower end of the pin is structurally fixed within the jacket by an engaging notch and lug assembly and the upper end of the pin is removably held within the jacket by an engageable ball and socket assembly. The foregoing apparatus allows a dental technician to employ the following method.
Having a female impression o~ the patient's mouth, the technician may then fill the impression with die stone material and insert the lower end of a pin unit, as described above, into the individual tooth model while the die stone is soft using the floater to position the pin unit in proper location and orientatio~
the floater being adapted to rest at the surface of the die stone material. When the die stone material has hardene~, the upper end of the pin unit will be protrudin~ and this can be embedded in a base material by pouring the base material on top of the die stone, this latter'step being taken after the jacket surround-ing the pin has been severed or weakened just above the floater.
When the base hardens the individual tooth die can be separated by cutting the die stone material on either side of the tooth die and the tooth die can be removed by pulling the tapered dowel pin out of the portion of the jacket embedded in'~the base (by overcoming the resistance of the ball and socket). The lower end of the jacket will, of course, remain embedded in the base material and provide ~ID~;9;~55 a firm resilient and precise socket into which the dowel pin can be re-inserted to replace the tooth die in its proper position and orientation.
A better understanding of the improved apparatus can be gleaned from a detailed description of one embodiment with reference to the enclosed drawings in which:
Figure 1 is a vertical cross-section of a tray containing an impression of a tooth filled with die stone material incorporating a dowel pin unit of the present invention;
Figure 2 is a horizontal cross-section of a dowel pin unit in accordance with this invention;
and Figure 3 illustrates a typical model of a patient's mouth showing a removable tooth die.
The cross-section of Figure 1 illustrates a stage in the making of a dental model using my improved dowel pin unit.
The tray 2 holds a quantity of impression material 4 which has been pressed over the appropriate portion o~ a patient's mouth to form a female impression of the patient's tooth (or teeth) and gums as represented by the impression profile 6, the lower end of which at 8 represents the configuration of the patientls tooth, while the upper portion represents the configuration of the gums at the base o~ the teeth.
Thus the technician is provided with an exact negative reproduction of the shape of the relevant portion of the patient's mouth, especially the teeth involved.
In order to perform the necessary prosthetic work, the technician will produce an exact model of the patient's teeth and gums by filling the negative impression with a fluid (but hardenable) material 10 known as die stone which, upon harden-ing, will produce a tough resilient model of the patient's teeth on which the technician can work.
Since the technician will want to work on an individual tooth die, it is desirable to separate the individual die from the rest of the model of the mouth and frequently during his work will want to remove and replace the tooth to its original position and orientation with respect to the rest of the model. To facili~ate this, the model is provided with one or more dowel pins such as illustrated at 12, the lower end of which is embedded in th~ die stone of the tooth and the upper half of which protrudes above the die stone where it is later embedded in a base material 14 which is poured over the die stone when the latter has hardened.
Conventionally, a dowel pin of previous design would be inserted either before the die stone was poured into the impression or after pouring but before the die stone had hardened.
Previous techniques for positioning dowel pins involved wire or other supporting devices which could be struck into the sides of the impression material or otherwise supported on the impression or tray to maintain the dowel pin in position while the die stone hardened. In the past, repeated removal and replacement of the individual tooth die, by withdrawing the dowel pin from its location in the base material and replacement thereof r developed inaccuracies because of wearing of the base material or the dowel pin itself or the inclusion of dirt or dust from the sides of the base material and other foreign material in the dowel pin recess in the ba~e~ For instance fine particles resulting from the wear on constant replacement and removal of the dowel pin would cause material to build up in the recess of the base material preventing proper snug ;9355 replacement of the dowel pin.
Figure 1 illustrates an improved design for a dowel pin unit in which the dowel pin 12 is encased in a jacket 16 of suitable material such as plastic, which has a series of ridges 18 (or other similar irregularities) about its outer surface so as to provide a firm structural bond with the surrounding die stone or base material in which it is encased.
Located approximately mi~way along the dowel pin unit and extending outwardly from the outer surface of the jacket is a floater 20 which is a flat horizontal planar element surrounding and extending out from the jacket 16 and adapted to lie, as illustrated in Figure 1, along the upper surface of the die stone material. In the usual case, as illustrated in Figure 1, this floater is positioned perpendicular to the long axis of the dowel pin but in certain cases might be set at an angle less than 90 thereto ~epending on the t~pe of model and the work being performed thereon.
~ ocated in the lower half of the dowel pin 12 is a notch 22, which may or may not extend around the entire circumference of the pin, and a corresponding lug 24 on the inner surface of the jacket located and dimensioned so as to engage snugly in the notch 22. This provides a firm tight engagement and structural bond between the lower end of the dowel pin and the jacket surrounding it. In the upper portion of the dowel pin is a pair of sockets 26 in the form of indentations in-the wall of the pin in a generally curved configuration of approximately the shape of a portion of a sphere. Correspondingly the jacket at the same location has on its inner surface a projecting ball portion 28 which engages snugly into the corresponding socket 26.
As can be seen in Figure 1, the dowel pin and its jacket are generally tapered from a wider portion embedded in the die stone to a narrower portion in the base material so as to facilitate removal of the pin from the base material when the technician is working on the model.
Figure 2 illustrates a corss-sectional view of the dowel pin unit including the dowel pin 12, the surrounding jacket 16 and the sockets 26. The cross-sectional shape illustrated and considered desirable is approximately a sector shape having two straight sides subtenaed by a curved third side. This configuration allows for easy replacement of the dowel pin within its recess in the proper orientation and avoids the possibility of error in replacing it in the wrong orientation.
The dowel pin also has an anchor 30 which is dove-tailed in cross-section so as to anchor the pin firmly in the die stone matçrial surrounding it.
The top end of the jacket covering the top end of the dowel pin is substantially thinner, almost in the nature of a membran~,--at 32-to allow for access to the top of the dowel pin for purposes described later.
Thus with the use of this dowel pin unit, a technician having an impression provided by known methods somewhat in the nature of that illustrated in Figure 1, can proceed to fill the impression with die stone material to approximately the level illustrated, place the model on a vibrator to remove voids and --level the fluid die stone, and then while the die stone is still soft, position a dowel pin unit as illustrated approximately co-axial with each individual tooth impression, inserting the broad end of the pin until the floater 20 rests along the top surface of the die stone material, as seen in Figure 1.
, ~0~935S
Although the eLement 20 i9 re~erred to as a floater it should be understood that it9 function does not depend purely on floatation in the sense that it provides buoyancy by virtue of its lighter specific gravity. To a large extent it may function by virtue of its broad area combined with the thick viscosity of the die stone fluid to maintain the orientation of the dowel pin unit.
The die stone material is then allowed to harden to substantial firmness thereby firmly embedding the lower end of the dowel pin unit therein.
After the die stone has hardened, the jacket of the dowel pin unit (being of plastic or other such material) can be severed around the circumference oX the pin at approximately the level of the top of the floater 20 so as to allow separation of the upper and lower halves of the jacket at a later stage in the pxocedure. Alternatively, the dowel pin unit might be fabricated with an indentation or weakness around its circumference just above the level of the floater which would allow separation of the two halves by exerting sufficient force.
A base is then formed by pouring base material 14 (plaster or some such similar material) on top of the die stone so as to substantially encase the upper end of the dowel pin and jacket. The tip of the dowel pin unit may be allowed to protrude from the top of the base although this is not necessary.
In accordance with conventional practice, it is preferable to coat the upper surface of the die stone material with a non-adhesive material to form a "separation coating" so that in subsequent operation the die stone material may be lifted and separated from the base material.
~L0693S5 When the die stone and base material are hardened, tray 2 and impression material 4 can be removed leaving a model of the patient's teeth, such as seen in Figure 3.
In order to remove a single tooth die a vertical cut is made on each side of the tooth, as at 34 and 36 respectively, in Figure 3, which cuts penetrate down to the line of interface between the die stone and the base m~terial. Because of the non-adhesive layer between those two materials they will separate at the plane of contact. By exercising some force the tooth die may be removed by pulling it out of the base with sufficient force to pull the narrow upper end of the dowel pin 12 out of its jacket, overcoming the resistance of the ball and socket engagement.
Thus the individual tooth 8 with its attached dowel pin 12 is available for further work by the technician. The individual tooth die may then be replaced in the model by re-inserting the end of the dowel pin 12 into the end of the jacket which remains embedded in the base material, as-seen at 38 in Figure 3.
This e~bedded portion of the jacket provides a tough I resilient-recess which-will be léss subjec-t-to-wear from numerous- - -I~ 20 movements of the tooth die. ~ecuase of the asymmetric (by which is meant it does not have an axis of symmetry though it may be - symmetrical about a chosen plane) cross-section the pin can only be inserted in one orientation. Furthermore, because of the ball and socket engagement the individual tooth member can be held firmly in the base material without accidentally falling out.
As shown in Figure 1, the narrow end of the dowel pin and jacket can be left protruding from the base material but if it is not, the base material may be ground down until the upper end is exposed. A small punch or other rod-lik~ instrument can be placed against the narrow end of-t~e dowel pin 12 and tapped so a~ to _ g _ lO~;9;~S5 assist disengaging the dowel pin from its jacket to remove the individual tooth model.
An a~ditional advantage to this invention may be achieved by using dowel pin units having a jacket of different colours of plastic. This would facilitate matching individual tooth dies back into their respective position by co-ordinating the colour of the floater and the other saparated part of the jacket embedded in the base material.
It may also be considered desirable to further anchor the floater to the die stone material by dove-tailed protrusions on the undeside of the floater, such as seen at 40 in Figure 1.
Although the notch and-lug 22 and 24 are shown substantially spaced from the level of the floater, they might be located closer to that mid point, as might the ball and socket assembly-26 and 28,- as may be dictated by design considerations.
Thus a dowel pin unit, as disclosed, can be used after the die;~stone material has been poured in liquid form into the impression,-is=vibrated-and begins to harden. The broad end of the dowel pin is inserted into the die stone down to the point where the floater rests on the upper surface of the die stone - material. The viscosity or thickness of the die stone material as it is hardening combined with the broad area of the floater will tend to keep the dowel pin unit in its upright position approx-imately coincident with the vertical axis of the individual tooth.
Where several such pins are inserted, they will tend to be substantially parallel which is important to facilitate removal of the dies and other work by the dental technician. Unlike previous methods, it is not so dependent on the technician being able to estimate the parallelism o~ the pins nor is the position ~L0~93SS
of the pin dependent on some auxiliary supporting device resting on the generally irregular outline of the impression mould.
Although a variety of materials might be used, it is considered advantageous that the pin be a strong material such as metal although it might be a strong plastic, and the jacket a firm, resilient, but not hard, plastic material. Since the lower end of the pin will be withdrawn from the lower end of the jacket it is desirable that the two materials be chosen or otherwise adapted to permit easy parting during the processes described above.
Various modifications and variations to the fore-going structure and method could be improvised without departing from the inventive concept herein.
Claims (9)
1. A dental dowel pin unit for use in dental models having a tooth die portion and a base portion, said unit comprising:
- a pin having an elongated configuration adapted to have one end thereof fixedly embedded in said tooth die material and the other end thereof adapted to be removably embedded in said base material;
- a jacket encasing said pin substantially throughout its length;
- at least one end of said pin unit being adapted to allow withdrawal of said pin from said jacket and replacement therein.
- a pin having an elongated configuration adapted to have one end thereof fixedly embedded in said tooth die material and the other end thereof adapted to be removably embedded in said base material;
- a jacket encasing said pin substantially throughout its length;
- at least one end of said pin unit being adapted to allow withdrawal of said pin from said jacket and replacement therein.
2. A dental dowel pin unit as claimed in claim 1 and having a floater, said floater comprising a flat planar member extending outwardly from said jacket intermediate said ends.
3. A dental dowel pin unit as claimed in claim 2 in which said jacket has a series of ridges on the outer surface thereof adapted to structurally bond said jacket to said die stone material and said base material in which it is adapted to be embedded.
4. A dental dowel pin unit as claimed in claim 3 including ball and socket means releasably engaging said pin with said jacket at the base end portions thereof.
5. A dental dowel pin unit as claimed in claim 4 including notch and lug means engaging said pin with said jacket at the tooth die end thereof.
6. A dental dowel pin unit as claimed in claim 5 in which the cross-sectional area of said pin and the interior of said jacket are asymmetrical to permit only one orientation of said pin in said jacket.
7. A dental dowel pin unit as claimed in claim 6 in which said pin has at the die stone end thereof a dove-tailed anchor engaging said die stone.
8. A dental dowel pin unit as claimed in claim 7 in which said floater is adapted to engage firmly with said die stone material by anchor means extending from the underside of said floater and adapted to be embedded in said die stone.
9. A method of preparing a dental model with tooth dies from an impression comprising the steps of:
- filling said impression with die stone material;
- placing in said die stone one end of a dental dowel pin unit adapted to be embedded therein; said dowel pin unit comprising a pin substantially surrounded throughout its length with a jacket and having a flat planar floater extending outward from said jacket intermediate its ends, so that said pin is co-axial with said tooth impression and said floater rests at the surface of said die stone material;
- allowing said die stone material to harden;
- providing means for separating said jacket immediately above the level of said floater;
- preparing said surface of said die stone for non-adhesion to base material;
- pouring a base material over said die stone material to surround the other end of said pin unit;
- allowing said base material to harden;
- cutting said die stone transversely on each side of said tooth die;
- removing said tooth die by separating said die stone from said base and disengaging the end of said pin from the portion of said jacket embedded in said base material.
- filling said impression with die stone material;
- placing in said die stone one end of a dental dowel pin unit adapted to be embedded therein; said dowel pin unit comprising a pin substantially surrounded throughout its length with a jacket and having a flat planar floater extending outward from said jacket intermediate its ends, so that said pin is co-axial with said tooth impression and said floater rests at the surface of said die stone material;
- allowing said die stone material to harden;
- providing means for separating said jacket immediately above the level of said floater;
- preparing said surface of said die stone for non-adhesion to base material;
- pouring a base material over said die stone material to surround the other end of said pin unit;
- allowing said base material to harden;
- cutting said die stone transversely on each side of said tooth die;
- removing said tooth die by separating said die stone from said base and disengaging the end of said pin from the portion of said jacket embedded in said base material.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000270246A CA1069355A (en) | 1977-01-21 | 1977-01-21 | Dental dowel pin unit and method using same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000270246A CA1069355A (en) | 1977-01-21 | 1977-01-21 | Dental dowel pin unit and method using same |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1069355A true CA1069355A (en) | 1980-01-08 |
Family
ID=4107795
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000270246A Expired CA1069355A (en) | 1977-01-21 | 1977-01-21 | Dental dowel pin unit and method using same |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1069355A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4721464A (en) * | 1985-06-17 | 1988-01-26 | Roden Mack L | Method and apparatus for making a dental model |
| USD303709S (en) | 1987-07-27 | 1989-09-26 | Roden Mack L | Combined dowel pin and parting guide for use in construction of a dental prosthetic |
| USD303836S (en) | 1987-07-27 | 1989-10-03 | Roden Mack L | Combined dowel pin and parting guide for use in the construction of dental prosthetics |
| FR2752723A1 (en) * | 1996-09-03 | 1998-03-06 | Demai France | Positioning assembly for moulded section e.g. of dental prosthesis |
| EP1190682A1 (en) * | 2000-09-13 | 2002-03-27 | Degussa Dental GmbH & Co. KG | Dowel pin for dental working model |
-
1977
- 1977-01-21 CA CA000270246A patent/CA1069355A/en not_active Expired
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4721464A (en) * | 1985-06-17 | 1988-01-26 | Roden Mack L | Method and apparatus for making a dental model |
| USD303709S (en) | 1987-07-27 | 1989-09-26 | Roden Mack L | Combined dowel pin and parting guide for use in construction of a dental prosthetic |
| USD303836S (en) | 1987-07-27 | 1989-10-03 | Roden Mack L | Combined dowel pin and parting guide for use in the construction of dental prosthetics |
| FR2752723A1 (en) * | 1996-09-03 | 1998-03-06 | Demai France | Positioning assembly for moulded section e.g. of dental prosthesis |
| EP1190682A1 (en) * | 2000-09-13 | 2002-03-27 | Degussa Dental GmbH & Co. KG | Dowel pin for dental working model |
| US6672869B2 (en) * | 2000-09-13 | 2004-01-06 | Degussa Ag | Plug connection for jaw stump models |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |