Ceramic Dental Mill Blank Sealing for Edge Crack Prevention
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Solution Overview
Problem
Existing ceramic mill blanks for dental cutting and machining suffer from cracks or chips on the outer edge when repeatedly attached to and detached from dental milling machines, and machining near the edge is difficult due to issues with holding and engagement.
Innovation Solution
A ceramic mill blank design with a seal member on the outer peripheral surface, where the seal member's length is 50% or more of the circumferential direction, providing enhanced holding and preventing cracks or chips during repeated attachment and detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a ceramic mill blank is directly engaged with a metal holding tool, then the holding strength is sufficient, but cracks or chips occur in the mill blank during repeated attachment and detachment
Solution Approach 1:
A plastic member is introduced as an intermediary between the ceramic mill blank and the metal holding tool. The plastic member wraps around the outer peripheral surface of the mill blank and is engaged with the holding tool, preventing direct contact between the ceramic and metal. This mediator protects the brittle ceramic from mechanical damage during attachment and detachment operations while maintaining sufficient holding strength through the plastic member's engagement with the holding tool.
2Reliability
If a plastic member is connected to the outer edge of the ceramic mill blank, then cracks and chips are reduced, but the plastic member falls off during cutting and machining operations
Solution Approach 1:
The outer peripheral surface of the ceramic mill blank is treated in advance to provide roughness or protrusions before the plastic member is attached. This preliminary surface preparation creates mechanical interlocking features that prevent the plastic member from falling off during cutting and machining operations. The roughened surface or protrusions ensure the plastic member remains securely attached even under the stresses of machining operations.
3Reliability
If the entire outer edge is protected with a seal member, then cracks and chips are prevented, but machining near the outer edge becomes impossible
Solution Approach 1:
The plastic member is provided to cover only a specific portion of the outer peripheral surface rather than the entire circumference. This localized protection approach allows the mill blank to be protected from cracks and chips at the critical engagement area while leaving other portions of the outer edge available for machining operations. The selective coverage maintains both protection and machinability.
Data Source
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AI summary
To provide a ceramic mill blank for dental cutting and machining in which cracks or chips are not caused on the outer edge of the ceramic mill blank even if attaching to and detaching from a dental milling machine are repeated and it is possible to machine the vicinity of the outer edge of the ceramic mill blank. To provide a ceramic mill blank for dental cutting and machining, wherein, the ceramic mill blank for dental cutting and machining comprises a ceramic portion to be cut and machined and one or more seal members, the ceramic portion consists of a ceramic material which is not finally sintered, the ceramic portion has an outer peripheral surface which is engageable with a holding tool, the one or more seal members are provided on the outer peripheral surface of the ceramic portion, and a length of the one or more seal members is 50% or more of a length in a circumferential direction of the outer peripheral surface provided with the one or more seal members.