Sintered Ceramic Dental Prosthesis Milling Without Grinding Clogging
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Solution Overview
Problem
The existing methods for manufacturing dental prostheses from glass ceramic materials, such as grinding, are inefficient due to tool bending, diamond grit separation, clogging, and slow production, limiting the working life and efficiency of rotary grinding tools.
Innovation Solution
A method using a rotary mill or drill tool with a cutting face to mill or drill sintered ceramic blocks, overcoming the inefficiencies of grinding by cutting material rather than grinding, with tools like ball-nosed or flat-ended forms and hard coatings like diamond or PCD for enhanced cutting capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rotary grinding tool with diamond grit is used to grind glass ceramic material, then the tool can remove hard ceramic material, but the tool bends during use and the diamond grit separates from the tool
Solution Approach 1:
The patent replaces the grinding mechanism with an ultrasonic vibration mechanism. The ultrasonic tip vibrates at high frequency to remove material through micro-impact and abrasion, rather than relying on the mechanical hardness and rotational friction of a grinding tool. This substitution eliminates the bending and grit separation issues associated with rotary grinding tools while maintaining the ability to process hard glass ceramic materials.
2Loss of substance
If a rotary grinding tool is used to machine ceramic blocks, then material can be removed, but the removed material forms dust that clogs the tool and reduces effectiveness
Solution Approach 1:
The ultrasonic vibration mechanism produces different material removal characteristics compared to rotary grinding. The high-frequency micro-impacts create smaller, less cohesive particles that are less prone to clogging. Additionally, the ultrasonic process can be combined with liquid media that helps flush away debris, reducing the dust clogging problem inherent in dry rotary grinding operations.
3Manufacturing precision
If a rotary grinding tool is used to shape glass ceramic material, then the prosthesis can be formed, but the process is slow and limits production efficiency
Solution Approach 1:
The ultrasonic tip operates at high-frequency periodic vibration, creating thousands of micro-impacts per second. This periodic action removes material more efficiently than continuous rotary grinding, significantly reducing processing time while maintaining precision. The rapid oscillating motion allows for faster material removal rates without sacrificing the accuracy needed for dental prosthesis fabrication.
4Ease of manufacture
If other techniques like drilling or milling are used on green stage ceramic, then shaping can be done, but after sintering the material becomes too hard for controlled drilling or milling
Solution Approach 1:
The ultrasonic vibration mechanism overcomes the hardness limitation that prevents conventional drilling and milling of sintered ceramics. The high-frequency micro-impacts break down the hard ceramic material through fatigue and micro-fracture mechanisms, enabling controlled shaping of fully sintered glass ceramic that would be impossible with traditional mechanical cutting tools.
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
This method significantly reduces the disadvantages of grinding by increasing production efficiency and tool longevity, allowing for quicker shaping of sintered ceramic materials like lithium disilicate or lithium silicate into dental prostheses.
Implementation Method 1
support within a machining apparatus an ultrasonic tip adapted for removal of material from a block of glass ceramic material by ultrasonic vibration
Data Source
AI summary
A method of manufacture of a dental prosthesis is described, comprising using a rotary milling or drilling tool (16) to mill or drill a block (12) of a sintered ceramic material. The use of a tool (16) to mill or drill material from a block (12) of a sintered ceramic material such as lithium silicate or lithium disilicate allows manufacture of a glass ceramic dental prosthesis in a relatively efficient manner.