Transfixed Dental Prosthesis Screw Retraction Mechanism
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Solution Overview
Problem
The existing multiple prosthesis systems in dental implantology face challenges with mechanical stability due to oblique implant orientations, complicated manipulation of small transfixing screws, and risks of screw damage or loss during placement, which complicates the fitting and fixation process.
Innovation Solution
A transfixed multiple dental prosthesis design where transfixing screws are held captive in bores and can move between retracted and screwing positions, with a distal centering portion and progressive threading to facilitate correct screw engagement and reduce the risk of damage, and a dental implant with a blind inner bore to minimize conflicts with the screws.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transfixing screws are rendered captive in bores with permanent protrusion of threaded shank, then manipulation risks are limited, but conflict with dental implants occurs during placement
Solution Approach 1:
The transfixing screw is designed with a movable mechanism that allows it to transition between retracted and protruding positions. The screw can be pushed forward by the practitioner to engage the implant and then retracted back into the bore after engagement, transforming from a static permanent protrusion design to a dynamic movable design that adapts to different operational phases.
Solution Approach 2:
The screw is preliminarily positioned in a retracted state within the bore before the placement operation begins. This preliminary retraction prevents conflict with the implant during the introduction phase, and the practitioner can then advance the screw only when needed for engagement, performing the protrusion action at the optimal moment rather than having it permanently protruding.
2Manufacturing precision
If transfixing screws have very small dimensions, then fixation precision is improved, but manipulation difficulty increases and loss risk rises
Solution Approach 1:
A pushing tool or finger pusher is used as an intermediary device to manipulate the small transfixing screw. This intermediary tool allows the practitioner to advance and retract the tiny screw with ease, compensating for the screw's small dimensions while maintaining the precision benefits of the small screw size for accurate implant engagement.
Solution Approach 2:
The transfixing screw incorporates a self-retaining mechanism with a head that engages with the pushing tool or finger, allowing the screw to be manipulated without requiring complex holding devices. The screw's own structural features (head geometry, threading) enable it to be advanced and retracted through simple linear motion, making the small screw self-sufficient for manipulation.
3Ease of operation
If threaded shank permanently protrudes from bore, then screw engagement is facilitated, but damage risk to threading increases during placement
Solution Approach 1:
The threaded shank transitions from a permanently protruding state to a retracted state after engagement. The dynamic movement allows the screw to protrude only when needed for engagement with the implant, minimizing exposure time and reducing the risk of damage from conflicts with surrounding structures during the placement procedure.
Solution Approach 2:
The bore is designed with sufficient depth and appropriate internal geometry to cushion and protect the threaded shank when retracted. The bore walls provide protective confinement that prevents accidental damage to the threading, and the retracted position serves as a safe, cushioned state before the screw is deliberately advanced for engagement.
Data Source
AI summary
Transfixed multiple dental prosthesis intended to be attached and fixed to a plurality of dental implants by several transfixing screws, each having a shank with a threaded portion intended to be received by screwing in a respective dental implant. Each transfixing screw is held captive in a respective bore formed in the transfixed multiple dental prosthesis and extending along a respective axial direction. Each transfixing screw is movable in rotation about the axial direction of the respective bore and is movable in translation along the axial direction of the respective bore between a retracted position and at least one screwing position. In the retracted position, the threading of the threaded portion of the transfixing screw does not protrude from the bore.