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Improved Non-Eugenol Temporary Dental Filling Formula
This document outlines an improved formulation for a non-eugenol temporary dental filling material, designed for enhanced performance and biocompatibility. The formulation incorporates a balanced composition of zinc oxide, calcium sulfate hemihydrate, a polymeric resin, plasticizer, anti-stick agent, fillers, and pigment, with optional additives for specific applications.
1. Formulation Composition
The following table details the components and their respective roles in the formulation:
| Component | Percentage by Weight | Function | Proposed Specifications | Additional Notes |
|---|---|---|---|---|
| Zinc Oxide (ZnO) | 50-55% | Base material, reacts with water | * Particle size: ≤ 10 μm * Purity: USP grade |
Particle size affects consistency and setting time. |
| Calcium Sulfate Hemihydrate (CaSO₄·½H₂O) | 15-20% | Hardening agent | * Particle size: 20-50 μm * Purity: Medical grade * Controlled dehydration |
Particle size and dehydration level influence setting time and strength. |
| Poly(ethyl methacrylate-co-methyl acrylate) (PEMA/PMA) | 8-12% | Binder, improves strength | * Molecular weight: 50,000 – 150,000 g/mol * Polymerization method: Suspension or emulsion |
Molecular weight and polymerization method affect flexibility and strength. |
| Tributyl Citrate | 3-5% | Plasticizer | * Purity: Medical grade * Stability: Thermally and chemically stable |
Provides workability; safer alternative to phthalates. |
| Calcium Stearate | 1-2% | Anti-stick agent | * Particle size: ≤ 5 μm * Purity: Medical grade |
Improves handling and texture. |
| Silicon Dioxide (SiO₂) | 3-7% | Filler, enhances strength | * Particle size: * Nano-sized (10-50 nm) for mechanical strength * Micro-sized (1-10 μm) for bulk * Type: Amorphous, surface-treated (if nano) |
Nano-silica requires proper dispersion to prevent agglomeration. |
| Calcium Silicate Glass | 2-3% | Bioactive filler | * Particle size: 1-20 μm * Composition: Optimized for calcium ion release |
May provide therapeutic benefits. |
| Titanium Dioxide (TiO₂) | 0.5-1% | Pigment | * Particle size: ≤ 1 μm * Purity: Medical grade |
Improves aesthetics. |
| Chlorhexidine Diacetate (Optional) | 0.2% | Antimicrobial agent | * Particle size: ≤ 10 μm * Encapsulated for controlled release |
Reduces bacterial growth; may affect mechanical properties. |
2. Material Specifications and Rationale
Each component is carefully selected to contribute to the overall properties of the filling material:
- Zinc Oxide: Provides the bulk of the material and reacts with water to contribute to the hardening process.
- Calcium Sulfate Hemihydrate: Acts as a hardening agent, setting upon contact with moisture.
- PEMA/PMA Copolymer: Functions as a binder, holding the components together and improving the material’s strength and flexibility.
- Tributyl Citrate: A plasticizer that enhances the material’s workability and flexibility, offering a safer alternative to phthalate plasticizers.
- Calcium Stearate: An anti-stick agent that prevents the material from adhering to instruments and improves its texture.
- Silicon Dioxide: Used in both nano and microparticle forms to enhance mechanical strength and reduce shrinkage.
- Calcium Silicate Glass: A bioactive filler that may release calcium ions, potentially aiding in healing.
- Titanium Dioxide: A pigment used to achieve a desirable aesthetic appearance.
- Chlorhexidine Diacetate (Optional): An antimicrobial agent added to reduce bacterial growth in the filling.
3. Manufacturing Process
The manufacturing process involves several critical steps to ensure a homogenous and high-quality product:
3.1. Material Preparation
- Particle Size Reduction: If necessary, raw materials are milled to achieve the specified particle sizes.
- Surface Treatment: Nano-sized silica particles are surface-treated to improve dispersion and compatibility with the resin.
- Drying: Calcium sulfate hemihydrate is carefully dried to control its hydration level.
3.2. Mixing
- Dry Mixing: Zinc oxide, calcium sulfate hemihydrate, silica, calcium silicate glass, calcium stearate, titanium dioxide, and chlorhexidine diacetate (if used) are dry-mixed in a suitable blender to achieve a uniform powder mixture.
- Wet Mixing: The dry mixture is then combined with the PEMA/PMA copolymer and tributyl citrate in a mixer. The mixing process is carefully controlled in terms of speed and duration to ensure homogeneity and prevent air entrapment.
3.3. Quality Control
- Viscosity Measurement: The viscosity of the mixed material is measured to ensure it meets the required consistency.
- Setting Time Test: The setting time is tested to verify that it falls within the specified range.
- Homogeneity Check: The mixture is visually inspected to ensure uniform dispersion of components.
3.4. Packaging
- The final product is packaged in appropriate containers that protect it from moisture and contamination.
- Labeling includes clear instructions for use, storage conditions, and safety precautions.
4. Quality Control and Testing
Rigorous quality control measures are essential throughout the manufacturing process to ensure the final product meets the required specifications. Key tests include:
- Setting Time: To ensure the material sets within the clinically acceptable time frame.
- Compressive Strength: To evaluate the material’s ability to withstand forces in the oral cavity.
- Flexural Strength: To assess the material’s resistance to bending.
- Water Sorption and Solubility: To determine the material’s stability in the oral environment.
- Biocompatibility: To ensure the material is safe for use in the oral cavity and does not elicit adverse reactions.
- Radiopacity: To verify that the material is visible on radiographs.
5. Safety Precautions
- Appropriate personal protective equipment (PPE) should be used during handling and mixing of the materials.
- The materials should be stored in a cool, dry place away from moisture.
- In case of contact with eyes or skin, flush thoroughly with water.
- Keep out of reach of children.
6. Disclaimer
This formulation is provided for informational purposes only and should be used as a starting point for further research and development. It is the responsibility of the user to validate the formulation and ensure it meets all applicable regulatory requirements and safety standards.