Hand Instrumentation for Periodontal Therapy

Core Review

Instrument Categories

Periodontal hand instruments fall into three major categories:

1. Sickle Scalers — Supragingival use; remove supragingival calculus 2. Universal Curettes — Supragingival and subgingival use; all tooth surfaces with a single instrument 3. Gracey Curettes (Area-Specific) — Subgingival use; designed for specific tooth surfaces and areas

Sickle Scalers

Design Features:

• Blade: Triangular cross-section with a pointed tip and back
• Cutting edges: TWO cutting edges formed by the junction of the lateral surfaces with the face
• Face: Perpendicular (90°) to the lower shank
• Tip: Pointed (sharp) — this is the key identifying feature
• Shank: Designed to reach specific areas; anterior vs. posterior sickles

Indications:

• Primary use: Removal of SUPRAgingival calculus ONLY
• The pointed tip can traumatize subgingival tissues; sickle scalers must not be used subgingivally
• Effective on heavy, tenacious supragingival deposits

Types of Sickle Scalers:

Technique with Sickle Scalers:

• Angulation: 70-80° between the blade face and tooth surface
• Use short, overlapping, controlled strokes
• Adapt the blade to the tooth surface (the small working end makes contact on a small area)
• The pointed tip must NOT contact soft tissue

Universal Curettes

Design Features:

• Blade: Semicircular cross-section with a rounded toe and back
• Cutting edges: TWO cutting edges (both sides of the blade)
• Face: Perpendicular (90°) to the lower shank
• Toe: Rounded — this is the key identifying feature (safe for subgingival use)
• Shank: Can be straight or curved; parallels the tooth surface
• Universal curettes can be used on ALL tooth surfaces without changing instruments

Why "Universal"? In a universal curette, the face of the blade is at a 90° angle to the lower shank. This means BOTH cutting edges can be used by simply tilting the instrument. Because the face is perpendicular, the cutting edges are at equal angles to the shank — making both edges equally usable. One instrument adapts to mesial, distal, facial, and lingual surfaces.

Common Universal Curettes:

Technique with Universal Curettes:

• Angulation: 70-80° between the face and tooth surface
• Adapt the rounded toe against the tooth surface
• The lower shank must be parallel to the tooth surface being instrumented
• For mesial surfaces: the lower shank is positioned toward the mesial surface
• For distal surfaces: the lower shank is positioned toward the distal surface

Gracey Curettes (Area-Specific Curettes)

Design Features That Differ from Universal Curettes:

• Cutting edge: Only ONE cutting edge is used per instrument (the lower cutting edge when the instrument is held in a modified pen grasp)
• Face: OFFSET at approximately 60-70° to the lower shank (NOT perpendicular). This is the key design distinction from universal curettes
• Blade: Curved to fit specific tooth surfaces
• Toe: Rounded (subgingival safety)
• Shank: Area-specific angulation designed to match the contours of the specific teeth the instrument is intended for

The Offset Face: Why Graceys Are Area-Specific The offset face means the blade is "tilted" relative to the shank. This creates a self-angulating design: when the lower shank is held parallel to the tooth surface, the offset blade naturally presents the correct cutting edge at the correct angulation. But because of the offset, only ONE cutting edge makes contact at the proper angle. The other cutting edge would be at an extremely acute or obtuse angle and is not clinically useful.

This is why Graceys are "area-specific" — each Gracey is designed for specific surfaces, and you must select the correct Gracey for the surface being instrumented.

Common Gracey Curettes:

After Five and Mini Graceys:

• After Five: Extended lower shank (3 mm longer than standard) with a thinner blade. Designed for deeper pockets (≥5 mm) to reach apically without tissue distention
• Mini Five: Extended lower shank + shorter blade (half the length of standard). Designed for narrow, deep pockets, furcations, and root concavities

Using Gracey Curettes — Key Principles:

1. Identify the correct Gracey for the surface:
   • Posterior, direct facial/lingual → Gracey 7/8 or 9/10
   • Posterior, mesial → Gracey 11/12
   • Posterior, distal → Gracey 13/14

1. Position the lower shank: The lower shank must be parallel to the tooth surface being instrumented. This is the single most important adaptation rule.

1. Identify the correct cutting edge: The cutting edge that is LOWER (closer to the handle) when the instrument is held in a modified pen grasp is the working cutting edge. Tilt the terminal shank toward the tooth surface until the blade engages at 70-80°.

1. Adaptation: The toe-third of the blade should be adapted to the tooth surface for effective calculus removal and biofilm disruption.

Angulation: The Universal Rule

Regardless of instrument type, the working angulation between the blade face and the tooth surface is approximately 70-80°.

• 0° (closed angle): Blade face flat against the tooth. Used for biofilm disruption, tactile exploration, and burnishing (NOT for calculus removal — burnishes rather than removes deposits)
• 45-60°: The blade engages the deposit but may not be aggressive enough for heavy calculus
• 70-80°: OPTIMAL WORKING ANGULATION. The blade engages and effectively removes calculus with controlled cutting strokes
• 90°: Tends to gouge or scratch the tooth surface; loss of tactile control

Instrument Grasps

• Modified Pen Grasp: The standard working grasp. The instrument is held between the thumb and index finger (first pad of thumb, second pad of index finger), with the middle finger resting on the shank near the working end. The ring finger serves as a fulcrum.
• Palm Grasp: Used for instruments with heavy shanks (e.g., some scalers). The handle is held in the palm of the hand.
• Palm-Thumb Grasp: Similar to palm grasp but the thumb stabilizes the handle.

Fulcrum

• Intraoral fulcrum: Ring finger placed on a stable tooth surface near the tooth being instrumented. The standard fulcrum.
• Extraoral fulcrum: Ring finger placed on the chin or cheek. Used when intraoral stability is limited.
• Advanced fulcrums: Cross-arch, opposite-arch, supplemental, and reinforced fulcrums for specific access challenges.

Instrument Sharpening

Sharp instruments are essential for effective treatment. Dull instruments:

• Require more lateral pressure (clinician fatigue, patient discomfort)
• Reduce tactile sensitivity
• Burnish calculus rather than remove it
• Prolong treatment time

Sharpening should maintain the original blade shape and angle. For sickle scalers and universal curettes: the face and lateral surfaces are sharpened at their junction. For Gracey curettes: only one side of the blade is sharpened (the side with the working cutting edge).

Clinical Application

You are treating a patient with generalized Stage II periodontitis. You need to instrument:

• Tooth #3 (maxillary right first molar), mesial surface, probing depth 5 mm → Gracey 11/12 (mesial posterior curette)
• Tooth #3, buccal furcation → Gracey 7/8 or 11/12 (for accessing the furcation concavity; also consider a mini Gracey for better adaptation)
• Heavy supragingival calculus on mandibular anteriors → Sickle scaler (H6/H7 or 204S)
• Tooth #30, distal surface, probing depth 6 mm → Gracey 13/14 (distal posterior curette)
• Generalized light subgingival deposits in shallow pockets → Universal curette (Barnhart 5/6 for anteriors, Columbia 13/14 for posteriors)

Common Traps

• TRAP: Selecting a Gracey 7/8 for the mesial surface of a posterior tooth. Gracey 7/8 is for facial and lingual surfaces; Gracey 11/12 is for mesial surfaces.
• TRAP: Using a sickle scaler subgingivally. The pointed tip traumatizes tissue. Sickles are for supragingival use only.
• TRAP: Confusing universal curettes and Gracey curettes. Universal = 90° face, two cutting edges. Gracey = offset face (~60-70°), one working cutting edge.
• TRAP: Thinking the upper cutting edge of a Gracey is the working edge. The LOWER cutting edge (closer to the handle) is the working edge.
• TRAP: Not adapting the lower shank parallel to the tooth surface. This is the single most important adaptation rule for Gracey curettes.