Selective Staining in 3D Printed Dental Restorations

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Solution Overview

Problem

Existing multi-color 3D printing processes for ceramic slips in dental restorations face challenges with high demands on print head compatibility due to particle size, fill level, viscosity, and abrasion, particularly when using highly filled ceramic slips.

Innovation Solution

A method and device for producing dental restorations by jet printing, which separates the selective application of ceramic slips and coloring solutions, allowing for the use of the same or different print heads for each process. This approach reduces the number of print heads required and improves the homogeneity and fixation of the dye solution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If pre-colored slips with different translucencies and mechanical properties are used for each color, then coloring precision is improved, but device complexity increases due to requiring multiple print heads

Engineering Contradiction:
Improvecoloring precisionVSAvoidnumber of print heads
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The process is segmented into two independent stages: first jetting the ceramic slip to build the green body, then separately jetting the coloring solution onto the dried slip layer. This separation allows each process to be optimized independently, reducing the need for multiple specialized print heads while maintaining coloring precision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The ceramic slip layer is dried completely before applying the coloring solution. This preliminary drying action prevents diffusion of the dye solution and ensures homogeneous coloring, while allowing the same print head to be used for both slip and color application.

Inventive Principle:
Principle #10Preliminary action

2Device complexity

If the same print head is used for both slip application and coloring, then device complexity is reduced, but manufacturing precision deteriorates due to cross-contamination and difficulty in selective application

Engineering Contradiction:
Improvenumber of print headsVSAvoidselective application precision
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The printing process is divided into two separate operations: slip jetting and coloring solution jetting. By separating these operations in time and allowing complete drying between them, a single print head can be used for both purposes without cross-contamination, maintaining selective application precision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Complete drying of the slip layer is performed as a preliminary action before applying the coloring solution. This ensures that the porous structure is fixed, preventing dye diffusion and enabling precise selective coloring even when using the same print head for both materials.

Inventive Principle:
Principle #10Preliminary action

3Productivity

If coloring is performed on wet slip layers, then productivity is improved by reducing process steps, but manufacturing precision deteriorates due to diffusion and running of the dye solution

Engineering Contradiction:
Improvecoloring process speedVSAvoidlocal homogeneity of coloring
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

Complete drying of the slip layer is performed as a preliminary action before applying the coloring solution. This creates a stable porous structure that prevents dye solution diffusion and running, ensuring local homogeneity and precise coloring control.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The moisture content parameter of the slip layer is changed from wet to completely dry state before coloring. This parameter change transforms the layer from a state that allows dye diffusion to a state that ensures homogeneous, controlled coloring while maintaining process efficiency.

Inventive Principle:
Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The method achieves efficient and crack-free drying of layers, reduces diffusion of the dye solution, and improves the natural appearance of dental restorations by allowing independent control of slip and dye application, ultimately leading to a reduction in the number of print heads needed.

Implementation Method 1

This process dries the jetted material layer without cracking

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 2

This achieves the technical advantage, for example, of causing a precipitation reaction of the dye solution

Methodology Applied
Scientific EffectPrecipitation reaction: Precipitation

Implementation Method 3

The applied dye solution is fixed using a caustic solution. This achieves the technical advantage of preventing the dye solution from running

Methodology Applied
Scientific EffectChemical fixation: Chemical Bonding

Implementation Method 4

the dental restoration is sintered in a sintering furnace. This achieves the technical advantage of producing a dental restoration with high strength

Methodology Applied
Scientific EffectSintering: Sintering

Data Source

PatentEP4563117A1Selective staining by staining solutions in 3D printing
Publication Date: 2025.06.04 IVOCLAR VIVADENT AG
  • EP4563117A1 patent drawingFigure 1
  • EP4563117A1 patent drawingFigure 2
  • EP4563117A1 patent drawingFigure 3

AI summary

The present invention relates to a method for producing a dental restoration (100) by jet printing, comprising the steps of jet printing (S101) one or more layers of the dental restoration using a ceramic slip; and jet printing (S102) a coloring solution onto the one or more layers.