Denture Tooth Units with Undercut-Free Gingival Lines for CAD/CAM Insertion

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Solution Overview

Problem

Existing methods for manufacturing dental prostheses, particularly artificial teeth, require multiple impressions and are dependent on the craftsmanship of dental technicians, leading to inefficiencies and potential faults in the prosthetic treatment process.

Innovation Solution

A dental unit with artificial teeth designed to have a visible outer part and an inner part with no undercuts, featuring a virtual gingival line in the undercut-free area, allowing for automated manufacturing processes such as CAD/CAM to create precise cavities in the denture base, ensuring easy and accurate tooth insertion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If automated manufacturing methods (CAD/CAM, 3D printing) are used to produce denture bases, then productivity and manufacturing precision are improved, but the complexity of the manufacturing process increases due to the need for digital data sets and virtual modeling

Engineering Contradiction:
Improvemanufacturing efficiencyVSAvoidprocess complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by creating a virtual data set of the tooth including the virtual gingival line before the actual manufacturing process. This virtual model prepares all necessary geometric information in advance, allowing the manufacturing system to automatically generate cavities and positioning features without requiring complex real-time calculations or multiple setup steps during production.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent uses copying by creating a virtual digital copy of the tooth with its complete geometry and gingival line information. This virtual model serves as a template that can be repeatedly used to generate accurate cavity definitions in the denture base, eliminating the need for physical prototypes or manual pattern making while maintaining high precision across multiple production runs.

Inventive Principle:
Principle #26Copying

2Measurement precision

If multiple impressions are taken during patient preparation, then measurement precision of the oral situation is improved, but the treatment time and patient inconvenience increase

Engineering Contradiction:
Improveoral situation accuracyVSAvoidtreatment time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces multiple physical impression-taking sessions with a single digital scan that creates a virtual model of the patient's oral situation. This digital copy captures all necessary geometric information in one measurement session, eliminating the need for multiple appointments while maintaining or improving measurement accuracy through digital documentation.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The patent substitutes the mechanical impression-taking process with optical or electromagnetic scanning technology. Instead of using physical impression materials and multiple manual procedures, a digital scanning system captures the oral anatomy, replacing the mechanical system with a non-contact measurement approach that is both faster and more precise.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Shape

If artificial teeth with undercuts are used, then the aesthetic appearance and anatomical accuracy are improved, but the ease of insertion into the denture base deteriorates

Engineering Contradiction:
Improvetooth anatomyVSAvoidinsertion ease
Core Design Contradiction:
ShapeVSEase of operation

Solution Approach 1:

The patent applies preliminary action by defining the virtual gingival line in advance during the virtual modeling stage. This allows the manufacturing system to pre-plan the cavity geometry and insertion path, ensuring that teeth with complex anatomical shapes including undercuts can be accurately reproduced while automatically generating the corresponding cavity structure that facilitates easy insertion.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent uses parameter changes by selectively modifying the geometry of the tooth root portion based on the virtual gingival line position. The system adjusts the cavity depth, shape, and positioning parameters to accommodate teeth with various degrees of undercut while maintaining a consistent insertion mechanism, allowing anatomical accuracy without compromising insertion ease.

Inventive Principle:
Principle #35Parameter changes

4Manufacturing precision

If the virtual gingival line is positioned at the boundary of the undercut-free area, then the adhesive gap definition is improved, but the visible tooth surface area may be reduced

Engineering Contradiction:
Improveadhesive gap definitionVSAvoidvisible tooth surface
Core Design Contradiction:
Manufacturing precisionVSArea of moving object

Solution Approach 1:

The patent uses parameter changes by allowing the virtual gingival line position to be adjusted as a variable parameter. The system can optimize the line position to achieve the best balance between defining a precise adhesive gap boundary and maximizing the visible tooth surface area, depending on the specific clinical requirements and tooth geometry.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by allowing different regions of the tooth to have different functional characteristics. The area above the virtual gingival line is optimized for aesthetics and visibility, while the area below is optimized for mechanical retention and adhesive bonding. This local differentiation allows each zone to serve its primary function without compromising the other.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3503840B1Tooth unit and method for producing a denture base
Publication Date: 2025.07.02 VITA ZAHNFABRIK H RAUTER GMBH & CO KG
  • EP3503840B1 patent drawingFigure 1~2
  • EP3503840B1 patent drawingFigure 3~4
  • EP3503840B1 patent drawingFigure 5

AI summary

Artificial teeth are inserted in a denture base in order to produce a denture. The artificial teeth used according to the invention have an outer part (12), which is visible in the inserted state. An inner part (14) is arranged in the denture base (20) in the inserted state. A virtual data record of the artificial tooth, which corresponds to the outer side of the tooth, helps to define a virtual gum line in a region of the inner part of the tooth, which is undercut-free. In order to produce a denture base, cavities (22) are created in the denture base. In order to be able to create the cavities (22) with the help of automatic production methods such as CAD/CAM methods, the artificial teeth are virtually subtracted from a virtual denture base (20) such that a cavity edge (24) is defined, which corresponds to the virtual gum line (10).