Module 8: Instrument Design and Classification

Design characteristics of periodontal instruments can

vary widely among manufacturers, consider handle, shank, and working end design

Instruments with ergonomic design help

prevent musculoskeletal injury during instrumentation, larger handle diameters and lightweight handles require less pinch force

Handle design is important in

prevention of musculoskeletal injury during instrumentation,

Recommended handle design

large handle diameter, lightweight hollow handle, handle tapers near shank, and raised texturing

Which is balanced

B

what does it mean for periodontal instrument to be balanced

working ends are aligned with long axis of handle, ensures that finger pressure applied against handle is transferred to working end for calculus removal

Simple shank:

also called straight shank

shank is bent in one plane, front to back, used primarily on anterior teeth

Complex shank:

also called angled or curved shank

shank is bent in two planes, front to back and side to side, used primarily on posterior teeth

Shanks on most periodontal instruments are bent in

one or more places to facilitate placement of working end against tooth surface

Why simple shank for anterior teeth

anteriors are wedge shaped and simple shank is long enough to reach along crown and onto root

Why complex shank on posterior teeth

posteriors have large, bulky crowns that are larger in diameter than roots, side to side bends allow you to reach mesial and distal surfaces of root, front to back allow you to reach facial and lingual surfaces of root

Removes heavy deposits

rigid shank

Removes small to medium deposits

flexible shank

Flexible shank characteristics

enhances amount of tactile information transmitted to clinician’s fingers, desirable for explorers used to detect deposits beneath gingival margin, vibrations created when working end quivers over tooth surface irregularities, vibrations are transmitted from working end through shank and into handle

Function shank:

portion of shank that allows working end to be adapted to tooth surface

Lower shank:

portion of functional shank that is nearest to working end, also called terminal shank

What is the heart portion

lower/terminal shank

What is the star portion

functional shank

What type of shank for supragingival use on anterior teeth

simple shank with short functional shank length

What type of shank for subgingival use on anterior teeth

simple shank with long functional shank length

What type of shank for supragingival use on posterior teeth

complex shank with short functional shank length

What type of shank for subgingival use on posterior teeth

complex shank with long functional shank length

What is A

standard lower shank

what is b

extended lower shank

instruments with extended lower shanks can reach

middle and apical third of root surface

What are single ended instruments

probes and mirrors

Double ended instruments may have

unpaired working ends or paired working ends

Unpaired working ends have

dissimilar working ends

Paired working ends have

mirror image working ends

Which is paired working end

green

which one is unpaired

red

What determines an instrument’s function

working end design

Parts of working end

face, back, lateral surfaces, cutting edges, toe or tip

Heart

face

star

back

lateral surface

cutting edge is sharp edge formed where face and lateral surfaces meet, most working ends have two cutting edges

toe

tip

Cross section of working end determines whether

instrument can be used subgingivally, below the gingival margin, or is restricted to supragingival use

Working ends that are triangular in cross section are

limited to supragingival use

Working ends that are semicircular in cross section may be used

supragingivally and subgingivally

Curets have what cross section and can be used

semicircular, supragingivally and subgivivally

Sickle scalers have cross section and can be used

triangular, limited to supragingival use

What is a probe

slender instrument used to evaluate health of periodontal tissues, blunt rod shaped working end

explorer

used to locate calculus deposits, tooth irregularities, and defective restoration margins, circular in cross section

sickle scaler

used to remove supragingival calculus deposits, triangular in cross section, pointed tip, pointed back

curet

used to remove calculus deposits, semicircular in cross section, rounded toe, rounded back

periodontal file

used to crush large calculus deposits, each working end has several cutting edges