Proper Grasp

Grasp is one of the first techniques taught in preclinical education. Revisiting grasp may seem odd to experienced practitioners, yet it has a vital effect on instrumentation and ergonomics. Neither skill nor experience can compensate for improper grasp.

Grasp is influenced by the education received as a student, joint flexibility, and how a clinician is predisposed to hold a pen. The attention given to fundamentals can also widely vary in educational programs. If grasp was not carefully focused on and guided beyond the basics of the modified pen grasp, any number of variations can exist (Figure 1).

The discussion of grasp might be negligible if not for the direct impact on ergonomics—specifically the sustained musculoskeletal compromise that can occur. This injury happens primarily with activations involving lateral pressure, not assessment procedures. While broadened contact points on centers of finger pads can be used for inspection with a mouth mirror and assessment strokes when exploring or probing, they interfere with working strokes. Thus, elements of grasp, as they apply to the working stroke with bladed instruments, are of the utmost importance.

In learning the modified pen grasp for the dominant hand, most practitioners are instructed to begin with a pen grasp and then lift and reposition the middle finger forward to the index finger. Exactly where the middle finger makes contact with the instrument is the crucial point in establishing a functional grasp with optimal ergonomics. It may seem logical to maximize a finger tip’s or thumb’s area of contact on an instrument to keep it more secure or increase tactile surface area, but this interferes with the dynamics of activation.

Ergonomically sound instrumentation hinges on finite positioning of the fingers on the instrument. These points of contact, or grasp points, may seem inconsequential compared to other fundamentals. However, effective stroke activations that protect the musculoskeletal system ultimately depend on precisely positioned fingers. Grasp points that are out of alignment can severely hamper the effectiveness of instrumentation and also contribute to injury and impairment.

Muscle memory tends to become ingrained according to how instruments are customarily used. Making a shift to new grasp points from established technique is a drastic change and requires sustained attention initially. Target points drawn on fingers for practice on a typodont will serve as a reminder to monitor proper finger/thumb contact positioning on the instrument.

To find your correct grasp, position the fingers on the instrument as shown in Figure 2. Place the thumb and index finger opposite each other and draw the index finger back slightly behind the thumb.
The middle finger is positioned forward, ahead of the thumb. Use the precise location at the upper inside corner of the middle finger where the red target point is drawn (Figure 3). Thumb contact point is also on the inside corner—not the center and not the tip.

Index finger contact point is centered, in contrast to the thumb and middle finger. Note the spread stabilization achieved from the triangular points of contact (Figure 2).

The most critical contact point to maintain is the middle finger, followed by the thumb. A good way to self-check these contact points is to curve your fingers and thumb to form an “O” with your hand. Now straighten the index finger, letting the thumb and middle finger slide into contact with each other. They should meet at their respective grasp contact points.

Another factor to consider is the resting point of the handle—where the upper handle contacts the hand. This aspect of grasp is rarely focused on by practitioners once instrumentation becomes second nature. Thus, making a slight adjustment requires continuous monitoring until muscle memory can be reprogrammed.

The handle rest is actually a zone that spans the knuckle area, but the primary position for basic activations is at the upper proximal phalange, near but not past the junction of the metacarpal. The knuckle (metacarpophalangeal joint) delineates the boundary between a strong grasp that is stable and a weaker grasp that has no reinforcement. As the instrument handle moves past the knuckle toward the web of the hand, there is no stabilizing bone to counterbalance the finger grasp points. A handle rest in this spongy soft tissue area commits the clinician to a finger flexing activation for a working stroke. This flexion dynamic is taxing to the neuromusculature and can rapidly bring on fatigue while also placing the clinician at risk for MSD. In contrast, wrist rock activations are able to achieve strong leverage with relative ease and no muscular strain in the hand and fingers.

The location of the grasp on the handle relative to the working end is entirely dependent on the type of fulcrum used and the distance between the fulcrum and surface being instrumented. Basic intraoral fulcrums typically call for a close grasp, ie, close to the working end. Alternative fulcrums, such as cross arch or opposite arch fulcrums and extraoral hand rests, require the grasp to be extended back up the handle to span the distance between the fulcrum point and the area being instrumented (Figures 4 and 5). Note that grasp points and handle rest are maintained whether the position on the handle is close or extended.

Ergonomically sound instrumentation applies the principles of lever dynamics to achieve effective, sound activation without undue exertion of the musculoskeletal system. In order to apply these principles, precise positioning must be followed, making the often-overlooked components of finger contact points and handle rest of primary importance. Fine tuning these elements of grasp can preserve musculoskeletal health and permit achievement of efficient and predicable root preparation.

From Dimensions of Dental Hygiene. September 2005;3(9):26, 28.