Ceramic Dental Implant Screw Lock with Elastic Deformation
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Solution Overview
Problem
Dental prosthesis systems made of ceramic materials face issues with connecting screw loosening due to mechanical loads during chewing, as existing screw locking systems designed for titanium are not suitable for ceramics, and previous solutions like plastic screws are irreversible once tightened.
Innovation Solution
A dental replacement system featuring a ceramic implant with a receiving opening for a connecting screw made of fiber-reinforced thermoplastic, utilizing a screw lock with first and second positive locking means that are elastically deformable, providing a secure fit by compressing and relaxing when tightened or loosened, preventing torsional forces and ensuring the connecting screw remains securely in place.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flat-conical screw locking system is used in ceramic implants, then screw loosening is prevented in titanium systems, but the system generates harmful outward forces that are not suitable for ceramics
Solution Approach 1:
Instead of using a conical screw head that locks against a conical hole (prior art), the invention inverts the approach by using a cylindrical screw head with a polygonal recess that engages with a corresponding polygonal protrusion on the implant. This inverted geometry eliminates outward radial forces while maintaining anti-loosening functionality through form-fitting engagement.
Solution Approach 2:
The invention changes the geometric parameters of the screw-implant interface from conical to cylindrical with polygonal features. This parameter change transforms the force distribution, converting radial outward forces into axial compressive forces that are beneficial for ceramic implants and prevent screw loosening without generating harmful lateral stresses.
2Reliability
If a plastic screw with incongruent threading is used, then a tight fit is guaranteed through cold welding, but the screw cannot be loosened reversibly
Solution Approach 1:
The screw connection is segmented into two functional zones: a form-fitting polygonal engagement zone that provides tight fit and anti-loosening, and a threaded zone that enables reversible tightening and loosening. This segmentation allows the screw to achieve both secure fitting and controllability without permanent deformation.
Solution Approach 2:
The screw is made of fiber-reinforced thermoplastic material that combines the benefits of plastic (cold welding capability for tight fit) with enhanced mechanical properties (reversible deformation, toughness). The composite material structure allows the screw to maintain tight engagement while remaining loosenable, overcoming the limitation of conventional plastic screws.
3Ease of operation
If conventional connecting screws are used in ceramic prosthesis systems, then installation is simple, but the screws loosen over time due to different material properties
Solution Approach 1:
The polygonal form-fitting features are pre-formed on both the screw and implant before assembly. This preliminary action ensures that when the screw is inserted, the form-fitting engagement immediately prevents loosening without requiring additional locking steps or complex installation procedures, maintaining simplicity while ensuring long-term stability.
4Ease of operation
If the connecting screw is made of fiber-reinforced thermoplastic, then the screw can be tightened and loosened reversibly, but the screw requires elastic deformability to engage with positive locking means
Solution Approach 1:
The fiber-reinforced thermoplastic composite provides the optimal balance between strength and elastic deformability. The fiber reinforcement enhances strength and stiffness to prevent permanent deformation, while the thermoplastic matrix maintains sufficient elasticity for reversible engagement with the positive locking means during tightening and loosening operations.
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 system effectively counteracts the loss of preload force on the connecting screw, preventing unintended loosening and ensuring the abutment remains securely fixed over the lifespan of the denture system, with a higher torque required to loosen the screw than to tighten it, thus enhancing stability and durability.
Implementation Method 1
the first positive locking means being elastically deformable in contact with the second positive locking means
Implementation Method 2
providing a secure fit by compressing and relaxing when tightened or loosened
Data Source
Figure 1(a)~1(c)
Figure 2(a)~2(b)
Figure 3(a)~3(c)
AI summary
The invention relates to a dental prosthesis system comprising a ceramic implant (1, 1') for osseointegration in a jaw bone with a receiving opening (14, 14') for a connection screw (7, 7', 7", 7"'), an abutment (2, 3, 4, 5, 5'), preferably made of a ceramic, wherein the abutment (2, 3, 4, 5, 5') can be secured in the receiving opening (14, 14') of the implant (1) by means of the connection screw (7, 7', 7", 7"') made of fibre-reinforced thermoplastic. A screw lock (60, 70, 80, 90, 100) comprises a first interlocking means (11, 11', 6', 61') and a second interlocking means (13, 12', 20, 6, 62'), wherein the first interlocking means (11, 11', 6', 61') is arranged on the connection screw (7, 7', 7", 7"') and the second interlocking means (13, 12', 20, 6, 62') is arranged in the receiving opening (14, 14') of the implant (1, 1') and/or on the abutment (2, 3, 4, 5, 5'). When tightening or releasing the connection screw (7, 7', 7", 7"') in the implant (1, 1'), the first interlocking means (11, 11', 6', 61') is elastically deformed in conjunction with the second interlocking means (13, 12', 20, 6, 62').