Root Canal Sealer Dispersion Stability
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Solution Overview
Problem
Conventional temporary root canal sealers face challenges with storage stability and in-use stability due to sedimentation of radio-opaque fillers and chemical reactions caused by harsh pH conditions, leading to premature solidification and ineffective sealing.
Innovation Solution
A temporary root canal sealer composition comprising a water-soluble polymer, particulate inorganic radio-opaque filler, alkali-resistant filler, alkali earth metal hydroxide, and humectant, combined in specific weight percentages and prepared through a dispersion process to stabilize the mixture and maintain radio-opacity and usability for extended periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high density radio opaque filler is used to improve radio-opacity, then radio-opacity is improved, but sedimentation occurs leading to poor storage stability
Solution Approach 1:
A surfactant is introduced as an intermediary substance between the radio opaque filler particles and the aqueous dispersion medium. The surfactant adsorbs onto the filler particle surfaces, providing steric or electrostatic stabilization that prevents aggregation and sedimentation, thereby maintaining both high radio-opacity and storage stability
Solution Approach 2:
The composition uses a composite system combining radio opaque filler particles with a surfactant-coated surface in an aqueous polymer dispersion. This composite structure allows the filler to maintain its high density for radio-opacity while the surfactant layer provides stabilization against sedimentation
2Stability of the object's composition
If strongly alkaline medium is used to maintain composition, then pH stability is improved, but hydrolysis and condensation reactions occur deteriorating components
Solution Approach 1:
The pH level is optimized to a specific alkaline range that provides sufficient stability without being excessively harsh. By carefully controlling the pH parameter within a narrow window, the composition maintains stability while minimizing hydrolysis and condensation reactions of the polymer and other components
3Productivity
If composition solidifies quickly after package opening, then sealing efficiency is improved, but in-use stability deteriorates
Solution Approach 1:
The composition exhibits dynamic rheological properties where its viscosity and solidification rate can be controlled. The polymer concentration and crosslinking mechanism are designed to allow the material to remain workable for a sufficient period after package opening, then progressively solidify to provide effective sealing
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 composition achieves high storage stability and in-use stability for at least 6 hours, preventing sedimentation and chemical reactions, ensuring effective sealing and radio-opacity during dental procedures.
Implementation Method 1
an aqueous dispersion medium, comprising an oligomer and/or polymer having Lewis basic groups
Implementation Method 2
a strongly alkaline aqueous slurry of calcium hydroxide
Implementation Method 3
a dispersed phase comprising a radio-opaque filler
Data Source
AI summary
A temporary root canal sealer composition, comprising based on the total weight of the composition: (a) 0.5 to 40 wt% of a water-soluble polymer having an average molecular weight of from 5000 to 100,000; (b) 20 to 40 wt% of a particulate inorganic radioopaque fiiier; (c) 0.01 to 5 wt.% of an alkali resistant particulate filler having an average particle size of from 1 to 100 nm; (d) 5 to 25 wt% of an alkali earth metal hydroxide and/or alkali metal hydroxide; (e) 15 to 45 wt% of water; and (f) 0 to 25 wt% of a humectant.