Patent Application
20190099247
The present method and invention in general relates to a flask made of aluminum or similar material for cold pour acrylics used to process dentures, acrylic dental prosthesis and acrylic implant retained bridges as well as any other manufactured products using conventional stone flask chambers in the lost wax technique.
Cold pour acrylic, also called cold cure acrylic is used to make temporary dentures, duplicate dentures, inexpensive basic or affordable dentures and denture repairs. The cold cure acrylic resin is generally processed in an electrically heated pressure vessel. When fabricating a dental prosthesis with cold cure acrylic the waxed prosthetic teeth and cast are placed in a duplicating flask designed for a duplicating material made of either a two part free flowing silicone or melted reversible hydrocolloid to be poured into the duplicating flask creating a negative impression of the waxed prosthesis. When the duplicating material becomes rigid the cast and waxed teeth are separated from the duplicating material where in the wax is removed from the cast and cleaned from the teeth. Once teeth and cast are thoroughly cleaned they are reinserted into the impression material and cold cure acrylic poured in through access holes of the flask. The flask is then placed into the electrically heated pressure vessel and cured at an appropriate pressure and temperature according to manufacturers recommendations. The duplicating materials associated with the cold pour technique however have constraints.
Reversible hydrocolloids require time constraints to chop and melt the material and bring the material to an ideal operating temperature. The ideal operating temperature being a temperature which allows the material to easily flow into a duplicating flask and reflect the detail of the waxed prosthesis without melting the wax and damaging the precise dimensions of the waxed prosthesis. There are also cost constraints with the availability of expensive equipment such as hydrocolloid conditioners designed to melt the hydrocolloid and keep the material at a constant operating temperature all the while mixing the material to keep it from congealing. Also necessary are cold running water baths, which cool the material for removing the waxed prosthesis from the duplicating material in a timely manner. Hydrocolloid is also highly susceptible to distortion when removing the waxed cast from the flexible material and it has poor dimensional stability causing a possible changed in the vertical dimension, affecting the accuracy of the final prosthesis' occlusion.
Free flowing Addition silicones mimic the accuracy of reversible hydrocolloid with a high dimensional stability. No reaction by products are formed as long as the correct proportions of one to one A-silicone are used. To achieve accuracy it is recommended to have a homogeneous mixing of the material to avoid streaks and voids. There are manufacturer-mixing machines available but add to the expense already associated with the higher price material costs of free flowing A-silicone and its single use nature. Free flowing Addition silicones are also limited to a fairly low Shore hardness, usually in the low twenties and teens. Lab silicones with a lower Shore hardness will demonstrate lower stiffness; unfortunately decreased stiffness may allow the matrix to be easily deformed effecting vertical dimension.
The present invention comprises an improved dental flask and method that allows for traditional, inexpensive materials such as dental stone and lab putty to create a rigid and stable matrix surrounding a waxed form, allowing for the creation of a final prosthesis. By utilizing the dental reline jig with the improved dental flask it is possible to preserve the vertical dimension of the waxed formed prosthesis, recreating the accuracy of the established occlusion quickly and dependably without the cost of expensive equipment and materials. The improved dental flask allows for the reduction of production time and material costs in the processing of cold cure acrylic. The improved dental flask is repeatable and dependable technology that uses standard flask materials and processing techniques such as a durable stone matrix and the ability to boil out the wax form from the chamber due to the material's rigidity and insulating nature to the stone matrix.
In accordance with the present method and invention, an improved dental flask is provided which enables an acrylic dental prosthesis to be processed within a dental reline jig using acrylic resin in the cold pour technique.
An improved dental flask (B) is shown generally in
A putty matrix (F)
The size of the waxed dental prosthesis' (E) cast model will determine the size needed of the improved dental flask and back plate (C). Inserting the back plate's (A) slots 5 and 6 into either slots 1 and 2 (large flask chamber
Once assembled the improved dental flask and back plate (C) are placed on a smooth flat surface. The waxed dental prosthesis' (E) cast must be trimmed to slightly less then 90 degrees, beaded with utility rope wax and brushed with model separator (tinfoil substitute) to ease in it's removal from the flask after the boil out stage. The back of the waxed dental prosthesis (E) and putty matrix (F) is centered into the flask chamber against the back plate (A) in
The investment material is poured into the flask chamber encompassing the retention wires (G), the waxed dental prosthesis (E), and putty matrix (F) up to the level of the improved dental flask's (B) relief area 11
Once the investment is cured according to manufacturers instructions the back plate (A) is removed and the excess stone cleaned from around the sprue holes and the back area of the waxed dental prosthesis' (E) cast. The waxed dental prosthesis' (E) cast if not already indexed at this time should be and all other areas of the flask's investment base needs to be brushed with model separator (tinfoil substitute). The two halves of the dental reline jig (D) are then reassembled with dental mounting stone attaching the bottom half of the dental reline jig (I)
