📖 Conservative Dentistry
Dental Mercury Hygiene Recommendations
Conservative Dentistry- Use of amalgam separators: Dental offices should install and maintain amalgam separators to capture at least 95% of amalgam particles before they enter the wastewater system. This reduces the release of mercury into the environment.
- Vacuum line maintenance: Regularly replace the vacuum line trap to avoid mercury accumulation and ensure efficient evacuation of mercury vapor during amalgam removal.
- Adequate ventilation: Maintain proper air exchange in the operatory and use a high-volume evacuation (HVE) system to reduce mercury vapor levels during amalgam placement and removal.
- Personal protective equipment (PPE): Dentists, hygienists, and assistants should wear PPE, such as masks, gloves, and protective eyewear to minimize skin and respiratory exposure to mercury vapor and particles.
- Mercury spill management: Have a written spill protocol and necessary clean-up materials readily available. Use a HEPA vacuum to clean up spills and dispose of contaminated materials properly.
- Safe storage: Store elemental mercury in tightly sealed, non-breakable containers in a dedicated area with controlled access.
- Proper disposal: Follow local, state, and federal regulations for the disposal of dental amalgam waste, including used capsules, amalgam separators, and chairside traps.
- Continuous monitoring: Implement regular monitoring of mercury vapor levels in the operatory and staff exposure levels to ensure compliance with occupational safety guidelines.
- Staff training: Provide regular training on the handling of dental amalgam and mercury hygiene to all dental personnel.
- Patient communication: Inform patients about the use of dental amalgam and the safety measures in place to minimize their exposure to mercury.
- Alternative restorative materials: Consider using alternative restorative materials, such as composite resins or glass ionomers, where appropriate.
Primary Retention Form
Conservative DentistryPrimary Retention Form in Dental Restorations
Primary retention form refers to the geometric shape or design of a prepared cavity that helps resist the displacement or removal of a restoration due to tipping or lifting forces. Understanding the primary retention form is crucial for ensuring the longevity and stability of various types of dental restorations. Below is an overview of primary retention forms for different types of restorations.
1. Amalgam Restorations
A. Class I & II Restorations
- Primary Retention Form:
- Occlusally Converging External Walls: The walls of the cavity preparation converge towards the occlusal surface, which helps resist displacement.
- Occlusal Dovetail: In Class II restorations, an occlusal dovetail is often included to enhance retention by providing additional resistance to displacement.
B. Class III & V Restorations
- Primary Retention Form:
- Diverging External Walls: The external walls diverge outward, which can reduce retention.
- Retention Grooves or Coves: These features are added to enhance retention by providing mechanical interlocking and resistance to displacement.
2. Composite Restorations
A. Primary Retention Form
- Mechanical Bond:
- Acid Etching: The enamel and dentin surfaces are etched to create a roughened surface that enhances mechanical retention.
- Dentin Bonding Agents: These agents infiltrate the demineralized dentin and create a hybrid layer, providing a strong bond between the composite material and the tooth structure.
3. Cast Metal Inlays
A. Primary Retention Form
- Parallel Longitudinal Walls: The cavity preparation features parallel walls that help resist displacement.
- Small Angle of Divergence: A divergence of 2-5 degrees may be used to facilitate the seating of the inlay while still providing adequate retention.
4. Additional Considerations
A. Occlusal Dovetail and Secondary Retention Grooves
- Function: These features aid in preventing the proximal displacement of restorations by occlusal forces, enhancing the overall retention of the restoration.
B. Converging Axial Walls
- Function: Converging axial walls help prevent occlusal displacement of the restoration, ensuring that the restoration remains securely in place during function.
Glass Ionomer Cements
Conservative DentistryGlass ionomer cement is a tooth coloured material
Material was based on reaction between silicate glass powder & polyacrylicacid.
They bond chemically to tooth structure & release fluoride for relatively long period
CLASSIFICATION
Type I. For luting
Type II. For restoration
Type II.1 Restorative esthetic
Type II.2 Restorative reinforced
Type III. For liner & bases
Type IV. Fissure & sealent
Type V. As Orthodontic cement
Type VI. For core build up
Physical Properties
1. Low solubility
2. Coefficient of thermal expansion similar to dentin
3. Fluoride release and fluoride recharge
4. High compressive strengths
5. Bonds to tooth structure
6. Low flexural strength
7. Low shear strength
8. Dimensional change (slight expansion) (shrinks on setting, expands with water sorption)
9. Brittle
10.Lacks translucency
11.Rough surface texture
Indications for use of Type II glass ionomer cements
1) non-stress bearing areas
2) class III and V restorations in adults
3) class I and II restorations in primary dentition
4) temporary or “caries control” restorations
5) crown margin repairs
6) cement base under amalgam, resin, ceramics, direct and indirect gold
7) core buildups when at least 3 walls of tooth are remaining (after crown preparation)
Contraindications
1) high stress applications I. class IV and class II restorations II. cusp replacement III. core build-ups with less than 3 sound walls remaining
Composition
Factors affecting the rate or setting
1. Glass composition:Higher Alumina – Silica ratio, faster set and shorter working time.
2. Particle Size: finer the powder, faster the set.
3. Addition of Tartaric Acid:-Sharpens set without shortening the working time.
4. Relative proportions of the constituents: Greater the proportion of glass and lower the proportion of water, the faster the set.
5. Temperature
Setting Time
Type 1 - 4-5 min
type II - 7 min
PROPERTIES
Adhesion :
- Glass ionomer cement bonds chemically to the tooth structure->reaction occur between carboxyl group of poly acid & calcium of hydroxyl apatite.
- Bonding with enamel is higher than that of dentin ,due to greater inorganic content.
Esthetics :
-GIC is tooth coloured material & available in different shades.
Inferior to composites.
They lack translucency & rough surface texture.
Potential for discolouration & staining.
Biocompatibilty :
- Pulpal response to glass ionomer cement is favorable.
- Pulpal response is mild due to
- High buffering capacity of hydroxy apatite.
- Large molecular weight of the polyacrylic acid ,which prevents entry into dentinal tubules.
a) Pulp reaction – ZOE < Glass Ionomer < Zinc Phosphate
b) Powder:liquid ratio influences acidity
c) Solubility & Disintegration:-Initial solubility is high due to leaching of intermediate products.The complete setting reaction takes place in 24 hrs, cement should be protected from saliva during this period.
Anticariogenic properties :
- Fluoride is released from glass ionomer at the time of mixing & lies with in matrix.
Fluoride can be released out without affecting the physical properties of cement.
ADVANTAGE DISADVANTAGE
Biologic Width
Conservative DentistryBiologic Width and Drilling Speeds
In restorative dentistry, understanding the concepts of biologic width and the appropriate drilling speeds is essential for ensuring successful outcomes and maintaining periodontal health.
1. Biologic Width
Definition
- Biologic Width: The biologic width is the area of soft tissue that exists between the crest of the alveolar bone and the gingival margin. It is crucial for maintaining periodontal health and stability.
- Dimensions: The biologic width is ideally approximately
3 mm wide and consists of:
- 1 mm of Connective Tissue: This layer provides structural support and attachment to the tooth.
- 1 mm of Epithelial Attachment: This layer forms a seal around the tooth, preventing the ingress of bacteria and other irritants.
- 1 mm of Gingival Sulcus: This is the space between the tooth and the gingiva, which is typically filled with gingival crevicular fluid.
Importance
- Periodontal Health: The integrity of the biologic width is essential for the health of the periodontal attachment apparatus. If this zone is compromised, it can lead to periodontal inflammation and other complications.
Consequences of Violation
- Increased Risk of Inflammation: If a restorative procedure violates the biologic width (e.g., by placing a restoration too close to the bone), there is a higher likelihood of periodontal inflammation.
- Apical Migration of Attachment: Violation of the biologic width can cause the attachment apparatus to move apically, leading to loss of attachment and potential periodontal disease.
2. Recommended Drilling Speeds
Drilling Speeds
- Ultra Low Speed: The recommended speed for drilling channels is between 300-500 rpm.
- Low Speed: A speed of 1000 rpm is also considered low speed for certain procedures.
Heat Generation
- Minimal Heat Production: At these low speeds, very
little heat is generated during the drilling process. This is crucial for:
- Preventing Thermal Damage: Low heat generation reduces the risk of thermal damage to the tooth structure and surrounding tissues.
- Avoiding Pulpal Irritation: Excessive heat can lead to pulpal irritation or necrosis, which can compromise the health of the tooth.
Cooling Requirements
- No Cooling Required: Because of the minimal heat generated at these speeds, additional cooling with water or air is typically not required. This simplifies the procedure and reduces the complexity of the setup.