Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
2002-03-27
2004-02-17
Paladini, Albert W. (Department: 2125)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C264S016000
Reexamination Certificate
active
06694212
ABSTRACT:
TECHNICAL FIELD
The present invention is related to the design of dental bridges. More particularly, the present invention is related to using computer-aided design in development and manufacture of a dental bridge that includes a pontic with retainers.
BACKGROUND
Dental bridges are used where a patient has a gap between two teeth. The gap forms an empty volume bounded by an adjacent tooth on each side and the gum line. The gap can result from an extracted tooth, a congenitally missing tooth, and other similar reasons. Conventionally, the adjacent teeth are ground down to make them suitable for crowns that adjoin the dental bridge and fix it in place when installed. The dental bridge is built by producing an artificial tooth that mounts to a frame, and the frame has the crowns attached to each side. The crowns are mounted on the teeth adjacent to the gap, and the artificial tooth between the two crowns fills the empty volume.
The conventional process requires that the adjacent teeth be ground even though they may be healthy teeth. Furthermore, the conventional process requires a relatively lengthy amount of time to prepare the bridge with the attached crowns. For example, a mold may be produced from the patient's mouth so that a manual process such as the lost wax technique may be used with the mold to make the framework for the bridge.
Computer-aided design has improved upon conventional approaches to designing and installing crowns. Computer imaging of the ground tooth to be crowned can be performed. From the computer image, computer-aided design software can propose a crown to fit the ground tooth and can communicate the design to a milling machine. The milling machine then mills a porcelain blank to produce the crown designed through the software.
One such computer aided design software is the CEREC family of software by Sirona Dental Systems. The CEREC family of software and machinery allows a dentist to image the area to crown, and the software analyzes the image to propose a crown to fit. The dentist may adjust the proposed crown as deemed necessary and then send the crown data to the milling machine of the CEREC system. The milling machine then mills the crown from a blank.
The current CEREC family of software is used to design a crown but lacks the functionality to propose and subsequently mill a complete dental bridge that is made up of a pontic to fill the empty volume and retainers to fix the pontic in place. A dental bridge including a pontic with retainers is a type of dental bridge that has retainers that may be bonded to the adjacent teeth. The retainer may be wing shaped for abutting an outer surface of an adjacent tooth, may be an in-lay to the adjacent tooth, may be a crown for the adjacent tooth, or other similar structure for attachment to adjacent teeth. Therefore; the adjacent teeth are not necessarily ground and fitted with a crown when installing the bridge unless the adjacent teeth are unhealthy.
The dental bridge including the pontic and retainers may be one continuous piece of ceramic without any additional support structure, thereby simplifying the construction of the bridge. Conventionally, a pontic with retainers is constructed in a manner similar in complexity to the conventional process for creating crowns. A mold may be taken and then from the mold, a model of the area may be made so that a manual process may be used to produce the pontic with retainers. This conventional process is lengthy and burdensome for the patient.
SUMMARY
Embodiments of the present invention provide methods and systems for using computer-aided design software to design bridges that are pontics with retainers. For one example, the CEREC software may be manipulated to enable design of a pontic with retainers. The manipulation of the CEREC software may occur through user intervention with the editing tools of the CEREC software to adapt structural details proposed by CEREC into a bridge structure. Alternatively, manipulation of the CEREC software to adapt to a bridge structure may occur through programming patches to the CEREC software that cause automatic adaptation of the details when selected by a user.
Embodiments of the present invention involve various steps for creating the dental bridge. The volume to fill with the bridge and at least portions of the adjacent teeth are imaged. A pontic with retainers is then specified in relation to the image so that the pontic fits in the volume and the retainers abut surfaces of the adjacent teeth. Generally, a computer executes the steps to create the proposed dental bridge as discussed above either automatically or through user interaction with an existing computer-aided design software such as CEREC.
The proposed dental bridge may be designed by shaping a bottom line of the proposed bridge so that it defines the shape of the base of the bridge including the pontic and retainers. The elevation of the bottom line is contoured to a profile line taken from the image data that specifies the gum line and the elevation of the surfaces of adjacent teeth where the retainers will fit. A proximal contact line is shaped and positioned to define a proximal area of the pontic that fits between the adjacent teeth and the retainers that abut the adjacent teeth. The proximal contact line is positioned to have an elevation above the bottom line. A labio-lingual line is shaped and positioned to define a labio-lingual area of the pontic that fits between the adjacent teeth and the retainers that abut the adjacent teeth. The labio-lingual line is positioned to have an elevation above the proximal contact line. An incisal line is shaped and positioned to define an incisal surface for at least the pontic which fits between the adjacent teeth. The bottom line, proximal contact line, labio-lingual line, and incisal line define a proposed dental bridge that is a pontic with retainers, and the data of the proposed bridge is used to mill the actual bridge from a blank.
The various aspects of the present invention may be more clearly understood and appreciated from a review of the following detailed description of the disclosed embodiments and by reference to the drawings and claims.
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Editor Werner H. Mörmann; Andreas Bindl, Björn Richter, Wiebke Apholt, Robert T. Toth; CERECComputer Aided Design Computer Integrated Manufacturing, Full-Ceramic Crowns; CAD-CIM Library vol. 2 dated 1999.
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