Layered Lithium Silicate Dental Restoration Production

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Solution Overview

Problem

Existing methods for producing dental restorations from lithium silicate glass ceramics require additional heat treatment steps and struggle to achieve desired coloration and translucency without complexity.

Innovation Solution

A method involving multiple layers of powders derived from different lithium silicate glass compositions, where the surface of one layer is structured to vary in height and the second layer is filled with a differing composition, allowing for mixing and pressing to achieve continuous optical transitions, eliminating the need for further heat treatment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If multiple layers of powders with different compositions are filled into a mold layer-by-layer to achieve desired coloration and translucency, then the optical properties of the dental restoration are improved, but the device complexity and manufacturing process become more complex

Engineering Contradiction:
ImprovetranslucencyVSAvoidmanufacturing process complexity
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The dental restoration is divided into multiple layers of powders with different compositions during the forming process. Each layer contains specific glass compositions (e.g., lithium silicate glass with different metal oxide contents) that provide different optical properties. This segmentation allows control of translucency and coloration in different regions of the restoration without requiring complex post-processing heat treatment steps.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The desired optical properties are built into the restoration during the initial forming process by pre-mixing powders with different compositions in specific layers. The coloration and translucency gradients are established beforehand through the layer-by-layer filling method, eliminating the need for subsequent heat treatment to achieve the desired optical characteristics.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If additional heat treatment steps are performed after production to achieve desired strength and optical properties, then the quality of the dental restoration is improved, but the production time and energy consumption increase

Engineering Contradiction:
ImprovestrengthVSAvoidproduction time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The forming process and heat treatment process are merged into a single integrated process. The multi-layer powder compact is directly sintered in one heating cycle that simultaneously achieves both formation and heat treatment. This eliminates separate heat treatment steps while maintaining the desired strength and optical properties of the restoration.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The sintering process parameters (temperature, time, atmosphere) are optimized to achieve both formation and heat treatment in one step. By controlling the sintering parameters appropriately, the restoration attains the required strength and optical properties without requiring additional post-processing heat treatment, thereby reducing production time and energy consumption.

Inventive Principle:
Principle #35Parameter changes

3Illumination intensity

If manual application and burning of coloration layers are required, then the desired aesthetic appearance is achieved, but the ease of manufacture decreases and additional processing steps are needed

Engineering Contradiction:
ImprovecolorationVSAvoidmanufacturing simplicity
Core Design Contradiction:
Illumination intensityVSEase of manufacture

Solution Approach 1:

The manual mechanical process of applying and burning coloration layers is replaced by an automated powder forming process. Powders with different compositions (including colorants) are filled into the mold in specific layers using mechanical means, and the coloration is integrated into the structure during sintering. This eliminates manual application and burning steps while achieving the desired aesthetic appearance.

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

Solution Approach 2:

The restoration is created as a composite structure with multiple powder layers containing different glass compositions and colorants. Each layer contributes specific optical properties, and the composite nature of the material allows desired coloration and translucency to be achieved directly during forming and sintering, without requiring separate manual application and burning operations.

Inventive Principle:
Principle #40Composite materials

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

Enables the production of dental restorations with desired coloration and translucency without additional heat treatment, allowing for continuous transitions in optical properties, facilitating direct use of the restoration without manual application and burning.

Implementation Method 1

at least one starting lithium silicate glass is melted

Methodology Applied
Scientific EffectMelting: Melting

Implementation Method 2

the glass melt is quenched

Methodology Applied
Scientific EffectQuenching: Cooling

Implementation Method 3

the material of the first layer is mixed with the material of the further layer to form an intermediate layer

Methodology Applied
Scientific EffectDiffusion: Diffusion

Implementation Method 4

the body sintered to produce the blank

Methodology Applied
Scientific EffectSintering: Sintering

Data Source

PatentEP3528742B1Method for the production of a dental restoration
Publication Date: 2025.01.08 DENTSPLY SIRONA INC
  • EP3528742B1 patent drawingFigure 1a~1d
  • EP3528742B1 patent drawingFigure 2
  • EP3528742B1 patent drawingFigure 3

AI summary

The invention relates to a method for the production of a restoration from a blank consisting of, or containing, a lithium silicate glass ceramic, wherein at least two layers of ceramic material of different compositions are filled into a mold layer-by-layer and after filling of the layers they are then pressed and sintered, wherein after filling of a first layer this is structured on its surface in such a way that the first layer, viewed across its surface, differs in its height from region to region, and then a layer with a composition that differs from the first layer is filled as a second layer into the mold. After sintering the dental restoration is produced from the blank by mechanical working.