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Access to the oral cavity defines health for the entire dental team. Without the right equipment, physical impairments and obstructions can cause clinicians to perform class 4 and 5 movements unnecessarily during procedures. Pelton & Crane’s narrow chair back allows the clinician to gain access to the oral cavity while maintaining an ergonomically correct posture and staying within healthy motion ranges.

Around, not Under

Improper leg positioning affects your health and hinders access to the oral cavity:

  • The narrow chair back allows more freedom to move around the patient and the ability to position the oral cavity at the proper height.
  • A narrow chair back enables a clinician to position their legs around the chair, allowing both the dentist/hygienist and assistant access to the oral cavity from any position.
  • With a wide chair back, the legs may be positioned underneath the chair potentially causing circulation issues and raising the oral cavity above a comfortable working height.

Relaxed, not Raised

Access to the oral cavity can be achieved at an optimal loupe height, allowing the arms to remain in a relaxed position.

  • A narrow chair back provides access to the oral cavity without the need for class 4 and 5 movements, potentially reducing the risk of musculoskeletal damage.
  • With a narrow chair back, the oral cavity is at a comfortable loupe height- allowing the clinician to work with arms relaxed and elbows at a 90+ degree position.
  • A wide chair back can cause the oral cavity to be positioned higher, forcing the clinician to raise their arms and elbows to gain access.

Straight, not Twisted

A narrow back chair reduces physical barriers, allowing access to the oral cavity without twisting or bending

  • The narrow chair back allows the clinician to work around the patient with the oral cavity at a comfortable loupe height, providing access to the oral cavity without twisting the trunk.
  • Placing the knees under a wide chair back can require you to bend and rotate the trunk to gain access.
  • Proper positioning allows for consistent focal length and working distance without the need for Class 5 movements.

Classification of Movements in Dentistry


Class 1 Movement of the fingers only
Class 2 Fingers and wrist motion when manipulating a hand piece or transferring
Class 3 Fingers, wrist and elbow when reaching for a hand piece
Class 4 The entire arm and shoulder as when reaching for supplies away from the work area, or adjusting an overhead light
Class 5 The entire torso as when turning around to reach for equipment from adjacent areas

*Source: The Journal of Contemporary Dental Practice, Vol. 1, No. 4 Fall Issue 2000