FPI ch8, ch15-17 Scalers

What are the three parts of a periodontal instrument?

The handle, the shank, and the working-end.

Which occupation ranks highest in the number of carpal tunnel syndrome cases in the United States?

Dental hygiene.

Name two risk factors for carpal tunnel syndrome in dental hygienists.

Repetitive forceful pinching during instrumentation and sustained non-neutral wrist positions.

What weight is optimal for an instrument handle?

Lightweight: 15 g or less.

What handle diameter requires the least pinch force?

A large diameter of about 10 mm.

Why does raised texturing (knurling) on a handle help?

It increases static friction between the fingers and handle, reducing pinch force and muscle fatigue in the wet oral environment.

How does a tapered handle help the clinician?

It improves coupling of the finger pads to the handle, reducing slipping and decreasing pinch force (about an 11% reduction).

When is an instrument considered balanced?

When the working-end is aligned with the long axis of the handle.

Why does instrument balance matter?

Finger pressure on the handle is transferred to the working-end and the tooth; an unbalanced instrument is harder to use and stresses the hand and arm muscles.

What is a simple shank, and where is it used?

A shank bent in one plane (front-to-back), also called a straight shank; used primarily on anterior teeth.

What is a complex shank, and where is it used?

A shank bent in two planes (front-to-back and side-to-side), also called an angled or curved shank; used on posterior teeth to reach around the rounded crown onto the root.

What is the difference between a rigid and a flexible shank?

A rigid shank withstands pressure needed for heavy calculus; a flexible shank bends under heavy pressure but works for small to medium deposits and transmits more tactile information.

Why do explorers have flexible shanks?

Flexible shanks enhance tactile sensitivity, which the clinician relies on to locate calculus hidden beneath the gingival margin.

Define tactile sensitivity.

The clinician's ability to feel vibrations transmitted from the working-end through the shank and handle to the fingers.

What is the functional shank?

The portion of the shank from just below the working-end to the last bend nearest the handle.

What is the lower (terminal) shank and why is it important?

The part of the functional shank nearest the working-end; it is the visual clue for selecting the correct working-end for a tooth surface.

How much longer is an extended lower shank than a standard one, and when is it used?

3 mm longer; used in deep periodontal pockets.

What does the design name versus the design number identify (e.g., Gracey 11/12)?

The name identifies the designer or institution; the number identifies the specific working-end in the series.

Name the parts of the working-end.

Face, back, lateral surfaces, cutting edges, and toe or tip.

Where is the cutting edge of a working-end formed?

Where the face and lateral surfaces meet.

What is the difference between a toe and a tip?

On a curet the cutting edges meet in a rounded toe; on a sickle scaler they meet in a point called a tip.

Why is the cross section of a working-end important?

It determines whether the instrument can be used subgingivally or is restricted to supragingival use.

What are the two major classifications of hand-activated periodontal instruments?

Assessment instruments (probes, explorers) and calculus removal instruments (sickle scalers, curets, periodontal files).

What is the function of a periodontal file?

To crush large calculus deposits.

What are the design characteristics of a sickle scaler's working-end?

Pointed back, pointed tip, triangular cross section, two cutting edges, and a face perpendicular (90 degrees) to the lower shank.

Where can sickle scalers be used and where should they not be used?

On crowns (enamel surfaces) only; they should not be used on root surfaces.

What size calculus deposits are sickle scalers best for?

Medium to large deposits.

What are the design characteristics of a universal curet's working-end?

Rounded back, rounded toe, semicircular cross section, two cutting edges, and a face at 90 degrees to the lower shank.

Why is a universal curet called "universal"?

It can be used on both anterior and posterior teeth, throughout the entire mouth.

What size deposits are universal curets used to remove, and where?

Small to medium deposits on both crown and root surfaces, supragingivally and subgingivally.

Which Nevi instruments are suited to primary teeth?

Nevi 1 (small, thin anterior sickle) for primary anteriors and Nevi 3 (thin, curved posterior sickle) for primary molars.

Why must you tilt the lower shank toward the tooth on a sickle or universal curet?

Because the face is 90 degrees to the lower shank, keeping the shank parallel to the tooth gives a 90-degree angulation; tilting it achieves the correct 70 to 80 degrees.

What can happen on a sickle scaler if angulation is 90 degrees?

The other cutting edge could traumatize the soft tissue and calculus removal is less efficient.

What portion of the cutting edge should be adapted to the tooth?

Only the tip-third (sickle) or toe-third (curet).

What can happen if the middle-third of a sickle's cutting edge is adapted instead of the tip-third?

The tip is free to catch and tear soft tissue, causing tissue trauma.

Why must you roll the instrument handle around a line angle?

To maintain adaptation of the tip- or toe-third to the tooth surface as you move onto the proximal surface.

How should a sickle be positioned relative to a pointed papilla?

The tip-third should hug the proximal surface and be positioned beneath the margin of the papillary gingiva, not tracing its contour.

What visual clue selects the correct working-end for a distal surface on posterior teeth?

The lower shank is parallel to the distal surface and the functional shank goes up and over the tooth ("Posterior = Parallel").

What visual clue selects the correct universal curet working-end on anterior teeth?

The lower shank goes across the tooth surface ("Anterior = Across"), and only the outer cutting edge is used.

Which cutting edges are used on posterior teeth for distal surfaces versus other surfaces?

The inner edge (closer to the handle) for distal surfaces; the outer edge (farther from the handle) for facial, lingual, and mesial surfaces.

What are the characteristics of a calculus removal stroke?

Short, controlled, powerful, made away from the soft tissue, with stabilization and moderate to firm lateral pressure.

What should the clinician do between calculus removal strokes?

Pause at least 3 seconds and relax the fingers in the grasp.

Where are vertical, oblique, and horizontal strokes most commonly used?

Vertical on anterior teeth and mesial/distal posterior surfaces; oblique on facial/lingual posterior surfaces; horizontal at line angles of posterior teeth and midlines of anterior surfaces.

Define stabilization and lateral pressure.

Stabilization is locking the ring finger joints and pressing the fingertip on a tooth to give control; lateral pressure is applying inward pressure with the index finger and thumb on the handle to press the working-end against the calculus or tooth.

Where is subgingival calculus commonly found?

Just apical to the CEJ, on line angles, and within furcation areas and root concavities.

Why is calculus important in periodontal disease?

It is always covered with living bacterial biofilm and creates plaque retention areas the patient cannot clean, so periodontal health cannot be reestablished while it remains.

What is the Get Ready Zone?

The area in the middle-third of the crown where the working-end is placed before insertion.

What is insertion, and what angulation is used?

Gently sliding the working-end beneath the gingival margin to the base of the sulcus or pocket with the face hugging the tooth at a closed angle of 0 to 40 degrees.

What face-to-tooth angulations are used for assessment, calculus removal, and root debridement?

Assessment about 40 degrees; calculus removal 45 to 90 degrees (ideal 60 to 80, with the stroke at 70 to 80); root debridement 60 to 70 degrees.

What are the three steps of a subgingival calculus removal stroke?

Assess, cup the deposit, then stroke (lock the toe-third, open the face to 70 to 80 degrees, and make a short biting stroke away from the pocket base).

How wide a strip of root does a cutting edge contact during one stroke?

Only about a 1- to 2-mm strip.

What are instrumentation zones and where do you begin?

Narrow strips of root surface instrumented systematically; begin in zone 1, removing the deposit nearest the pocket base first and working coronally.

What are multidirectional strokes and why are they used?

Overlapping vertical, oblique, and horizontal strokes (crosshatch pattern) used to make sure every millimeter of root surface is covered.

Is root smoothness a reliable indicator of successful subgingival instrumentation?

No; it helps locate calculus, but tissue response is the only true indicator of success.

When is the re-evaluation appointment scheduled and why?

4 to 6 weeks after instrumentation, because tissue healing is delayed and true tissue response takes at least a month to judge.

What is a nonresponsive disease site?

An area with deeper probing depths, continuing attachment loss, or continuing inflammation despite instrumentation about a month earlier; it may harbor residual calculus.

Does periodontal instrumentation regenerate bone, cementum, or periodontal ligament?

Normally no; soft tissue heals and probing depths may decrease, but there is no new formation of these structures.

Why should the clinician avoid collapsing the ring finger and tilting the handle toward themselves on mandibular lingual surfaces?

The lower shank hits the crown and rocks off the root without engaging calculus; keep the handle in the normal position and use the mirror for indirect vision.

Where do novice clinicians often miss calculus, and what stroke helps?

Near distofacial or distolingual line angles of posterior roots and at midlines of anterior roots; horizontal strokes help.

Why should the fulcrum finger be positioned "out of the line of fire"?

To prevent the ring finger from being stuck by the working-end when making a stroke.

What word choices should hygienists avoid when talking with patients, and what is better?

Avoid "cleaning," "prophy," "scale," and "root plane"; explain in everyday words how removing biofilm and calculus from beneath the gum line benefits the patient.