Operative Dentistry Lecture Notes

Introduction

• Presenter: Ryan
• Topic: Overview of hand instruments, handpieces, and burs in operative dentistry.

Categories of Dental Hand Instruments

• Two main categories:
  • Non-Cutting Instruments
  • Cutting Instruments

Structure of Dental Hand Instruments

• Components:
  • Handle (C):
    • Diameter: ~6mm; can be 8-sided or round.
    • May have ribbed grip or smooth/flat surface.
  • Shank (B):
    • May have bends to align the working end with the long axis of the handle.
  • Working End (A):
    • Should align with the handle for balance/control.
    • Consists of:
      • Blade & Cutting Edge (for cutting instruments).
      • Nib & Face (for non-cutting instruments).

Non-Cutting Dental Hand Instruments

1. Dental Mirror

   • Allows indirect vision of hard-to-see areas (e.g., occlusal surfaces).

2. Dental Explorer

   • Provides tactile sensitivity to check restoration margins, detect caries.
   • Variants include:
     • Shepherd's Hook (Number 23)
     • Back Action Explorer (Number 17)
     • Pigtail Explorer (Number 2)

3. Periodontal Probe

   • Measures pocket depths and other oral structures.
   • Variants include:
     • UNC 15 Probe
     • Williams Probe
     • Marquee Probe

4. Amalgam Condenser

   • Condenses amalgam into cavity preparations to avoid voids.

5. Ball Burnisher

   • Used for burnishing and contouring amalgam restorations.

Cutting Dental Hand Instruments

• General categories:
  • Scalers: Remove calculus.
  • Excavators: Remove carious dentin.
  • Chisels: Remove unsupported/friable enamel.

Formula for Cutting Instruments

• Four-number formula:
  1. Width of the blade (tenths of mm).
  2. Angle of cutting edge to long axis of blade (usually omitted if 90 degrees).
  3. Length of blade (mm).
  4. Angle of blade to long axis of handle (percentage of 360 degrees).

Common Cutting Instruments

• Spoon Excavators:
  • For gentle carious dentin removal (Formula: 11.5714).
• Enamel Hatchet: For planing enamel walls.
• Bin Angle Chisel: For planting walls of enamel.
• Gingival Margin Trimmer: For planting enamel at gingival floor.
  • Distal version (angle >90) and Mesial version (angle <90).
• Discoid Cleoid Carver: Carving and contouring amalgam.

Holding Instruments

• Normal Pen Grasp: Thumb and index finger holding, middle finger support.
• Modified Pen Grasp: Adds middle finger grip for better control.
• Importance of finger rest and short working radius for stability.

Rotary Instruments

1. Low-Speed Handpiece:
   • <12,000 RPM, used for cleaning, polishing, and caries excavation.
2. High-Speed Handpiece:

   • 200,000 RPM, used for tooth preparation.

3. Medium-Speed Handpiece:
   • Between low and high speed, less commonly used.

Anatomy of Burs

• Shank: Part inserted into handpiece.
• Neck: Transition to the head.
• Head: Cutting part of the bur.

Types of Burs

• Carbide Burs: Made of tungsten carbide, good for end cutting.
  • More blades = smoother cut (e.g., 6 blades for cutting, 12 blades for finishing).
• Diamond Burs: Better for side cutting, generates more heat, more expensive.

Commonly Tested Burs

• 245 Burr: 3mm long, 0.8mm diameter, pear-shaped.
• 330 Burr: 1.5mm long, 0.8mm diameter, smaller for pediatric use.
• 169 Elbow Burr: Tapered fissured design for retentive features.

Safety Considerations

• Protect pulp from heat, vibration, and desiccation.
• Use proper isolation techniques (cotton rolls, rubber dam).
• Protect eyes, ears, and reduce inhalation risks with PPE.

Conclusion

• Overview concludes with encouragement for further study.
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