Dental Abutment Reverse Margin Cement Extrusion
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Solution Overview
Problem
The existing dental implant systems often result in the extrusion of luting agent/cement below the gingiva during attachment of dental prostheses, leading to irritation, inflammation, and potential loss of the dental implant due to the sloped shoulder design that directs cement towards the gingiva.
Innovation Solution
A dental abutment design with a reverse margin, where the shoulder is angled away from the gingiva, directing any extruded cement away from the gingival area, and a corresponding prosthesis cavity with a tapered margin to facilitate cement ejection in an occlusal direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a sloped shoulder design is used for the abutment occlusal portion, then the prosthesis can be seated in close alignment with the abutment, but cement is extruded through the interface and injected below the gingiva causing irritation and inflammation
Solution Approach 1:
The patent inverts the traditional sloped shoulder design by creating a reverse margin where the shoulder slopes away from the gingiva rather than toward it. This inversion changes the direction of cement extrusion from gingival (harmful) to occlusal (safe), resolving the contradiction between achieving close alignment and preventing harmful cement injection.
Solution Approach 2:
The patent converts the potentially harmful cement extrusion into a beneficial outcome by redirecting it away from the gingiva. The reverse margin design ensures that any extruded cement is directed occlusally where it cannot cause irritation or inflammation, thus converting a harmful effect into a safe or even beneficial outcome for tissue health.
2Strength
If cement is compressed during prosthesis attachment, then the prosthesis is securely bonded to the abutment, but excess cement is extruded below the gingiva leading to potential loss of the dental implant
Solution Approach 1:
The reverse margin design converts the harmful effect of cement extrusion into a beneficial outcome by directing extruded cement away from the gingiva and implant interface. This allows adequate cement compression for strong bonding while preventing the extruded cement from compromising implant retention through tissue irritation or inflammation.
Solution Approach 2:
The reverse margin acts as an intermediary structure that mediates between the need for strong cement bonding and the need to protect the implant from cement-related damage. It provides a controlled path for cement extrusion that protects the critical implant-gingiva interface while still allowing sufficient cement compression for reliable bonding.
3Ease of manufacture
If a traditional sloped shoulder is used, then the design is simple and easy to manufacture, but it directs cement toward the gingiva causing irritation and inflammation
Solution Approach 1:
The patent applies the inversion principle by reversing the slope direction of the shoulder margin. Instead of sloping toward the gingiva as in traditional designs, the reverse margin slopes away from the gingiva toward the occlusal surface. This simple geometric inversion maintains ease of manufacture while fundamentally changing the direction of cement flow to eliminate gingival irritation.
Data Source
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Figure 3A~3C
Figure 4
AI summary
A dental abutment, or a dental implant having an integrated abutment, in which the occlusal part of the abutment to which the dental prosthesis is to be cemented features a shoulder having a reverse margin. At the point where the shoulder meets the outer profile of the gingival part of the abutment, the shoulder is at an acute angle with respect to the longitudinal center axis of the abutment, thereby causing any cement ejected during mounting of the prosthesis to be ejected in a direction away from the gingiva.