Dental Restorative Material Viscosity Control
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Solution Overview
Problem
Highly filled resin composite materials for dental restorations are difficult to place accurately due to their high viscosity, leading to incomplete filling and adaptation issues, while less filled materials lack strength and stability, and current vibration-assisted methods are inefficient and may cause temperature rises.
Innovation Solution
A dental restorative composition comprising a polymerizable resin, a translucent structural filler with specific particle size distributions and a nanofiller, and rheology-modifying additives, which exhibits a paste-like viscosity that can be reduced to a liquid-like consistency with vibrations, allowing for high strength, low polymerization shrinkage, and deep curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If highly filled restorative materials are used to provide mechanical strength, then strength is improved, but viscosity increases making placement difficult and technique sensitive
Solution Approach 1:
The patent utilizes ultrasonic vibrations applied through a placement instrument to temporarily reduce the viscosity of highly filled restorative material during placement. The vibrations cause the filler particles to move and settle more easily, allowing the material to flow into the cavity and adapt to cavity walls like a flowable composite, while maintaining high filler content for strength. After placement, the material returns to its paste-like consistency for easy shaping.
2Ease of operation
If less highly filled flowable materials are used to facilitate proper adaptation, then ease of operation is improved, but strength decreases and material flows under its own weight
Solution Approach 1:
The invention applies ultrasonic vibrations to highly filled paste-like material to temporarily reduce its viscosity, enabling it to flow and adapt to cavity walls like flowable materials while maintaining high filler content. This allows the material to achieve proper adaptation without sacrificing mechanical strength, as the high filler loading is preserved throughout the process.
3Reliability
If incremental layering technique is used to restore deep cavities, then polymerization shrinkage stress is reduced, but placement time increases and void formation risk increases
Solution Approach 1:
The patent applies ultrasonic vibrations during the placement of thick increments of restorative material to enhance light penetration and promote more uniform polymerization throughout the increment. This reduces polymerization shrinkage stress within the increment and minimizes void formation, allowing clinicians to place and cure thicker layers more reliably, thereby reducing the number of increments needed and overall placement time.
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
Enables simplified clinical placement with high mechanical strength, low polymerization shrinkage, and deep curing, allowing for bulk filling of cavities in fewer increments, reducing the risk of voids and improving restoration durability.
Implementation Method 1
It is known that particulate dispersions with high solids content, of which dental restorative composites are examples, typically exhibit shear-thinning and, in some cases, thixotropic behavior and that their viscosity can be lowered through the action of vibrations
Implementation Method 2
It is known that particulate dispersions with high solids content, of which dental restorative composites are examples, typically exhibit shear-thinning and, in some cases, thixotropic behavior and that their viscosity can be lowered through the action of vibrations
Implementation Method 3
Most commonly, especially in direct restorations, the restorative material is cured by exposure to actinic radiation
Data Source
Figure 1~2
Figure 3
AI summary
A dental restorative composition is provided that includes a polymerizable resin, a substantially translucent structural filler, a nanofiller having a mean particle size less than 100 nm, and at least one rheology-modifying additive. In one embodiment, the structural filler has a refractive index substantially similar to that of the polymerizable resin, a coarse particle fraction, and a fine particle fraction having a mean particle size greater than 0.1 µm and smaller than the mean particle size of the course particle fraction. The relative ratio of the coarse particle fraction to the fine particle fraction is in the range from 12:1 to 2:1 by volume, the particle size distribution of each fraction is essentially monomodal, and the D(90) of the fine particle fraction is less than or equal to the D(10) of the course particle fraction.