DHI 101

Identifying Hand Instruments

• Reference
  • By name
  • By assigned number
• Black’s instrument formula
  • Width of blade
  • Length of blade
  • Angle of blade

Most hand instruments are made of stainless steel, carbon steel, plastic, or specialized metal.

The dentist will refer to an instrument either by name or by number. This number is a universal representation of the instrument.

G.V. Black designed a formula that describes the angulations and dimensions of the working ends of hand instruments. 

Why is it important that the dental assistant have knowledge regarding instrument design and usage? 

Design of Hand Instruments

• Handle
  • Portion of the instrument that the operator grasps
• Shank
  • Part of the instrument that connects the working end to the handle
• Working end
  • Portion of the instrument designed for a specific function

What are the advantages to a handle with a larger circumference? (Larger handles are ergonomically designed to reduce fatigue and stress on hand muscles.)

Where would you use an instrument with an angled shank? (Posterior areas.) 

The working end may be a point, blade, or nib. Instruments can also be single- or double-ended. Double-ended instruments are mirror images or have reverse angles.

What are mirror-image instruments called? (Left and right instruments.)

Three parts of a dental hand instrument.

What information is found on the handle of a dental instrument? (Name of the instrument, manufacturer’s name, and the universal identification number.)

Classification of General Dental Instruments

• Examination
• Hand-cutting
• Restorative
• Accessory

In what procedures would an examination instrument be used? (Caries examination, inspection of the oral soft tissues, periodontal assessment.)

In what procedures are hand cutting instruments used? (Cutting bevels in the cavity prep, removing decay close to the pulp, removing soft dentin.)

In what procedures are restorative instruments used? (Amalgam placement, composite placement, etc.)

Can students name an accessory instrument?

Examination instruments.
A. Mirror.  B. Explorer.  C. Cotton Forceps.  D. Probe
(A-D from Boyd L: Dental instruments: a pocket guide, ed 3, St Louis, 2009, Saunders.) 

Mouth mirror: designed to have a straight handle, a slight angle to the shank, and a working end consisting of a round metal disk with a mirror on one side.

Why is the tip so thin on an explorer instrument? (Tactile sensitivity is increased.)

A periodontal probe is used to measure sulcus and pocket depths of the periodontium of each tooth. The working end is calibrated in millimeters.

 Can you think of something else the periodontal probe can be used to measure? (Oral lesions, the width of an anterior overjet.)

Uses for the mouth mirror.
A, Indirect vision. B, Light reflection. 
C, Retraction. D, Tissue protection.

What are the indirect areas of a patient’s mouth for the right-handed operator? 

Light reflection/reflective illumination: directs additional light into areas of the mouth. 

Retraction: helps maintain a clear field and protects the soft tissues from injury caused by the dental bur or hand instruments. 

What is another function of the dental mirror?

Hand (manual) cutting instruments.
(Photos from Boyd L: Dental instruments: a pocket guide, ed 3, St Louis, 2009, Saunders; Drawings in parts A, B, D, E, and F from Baum L, Phillips RW, Lund MR: Textbook of operative dentistry, ed 3, Philadelphia, 1995, Saunders.)

Hand cutting instruments are the group of instruments placed on the tray after the examination instruments. 

The spoon excavator is the most commonly used excavator.

The hoe is similar in appearance to a garden tool. The blade is perpendicular to the handle.

What function do you think the chisel has? Remember, it has a cutting edge. (Cutting enamel margins of the tooth preparation, forming sharp lines and point angles, placing retention grooves.)