Armamentarium 1

Armamentarium - I

Dr. Habiba Mumtaz Lecturer

Department of Operative Dentistry

Dental Instruments are used to examine, clean, cut and restore teeth

Main types are:

Hand-held instruments

Rotary instruments

Auxilliary instruments

1) Hand instruments Examining the mouth and teeth

Scalers

Cutting teeth and removing caries

Placing and condensing restorative materials

Carving and finishing restorations

miscellaneous

Hand instrument designMost hand instruments are made of

stainless steel or carbon steel (incase of some cutting instruments) and Teflon-coated

Some chisels and scalers have tungsten carbide tips brazed to the cutting edge. This helps them retain their sharpness for much longer

Majority of the instruments have 3 parts:-

Blade

Shank

Handle

For increased effectiveness, the working surface of the instrument must meet the surface at an angle

This facilitates in the access to awkward places where approach is impossible with a straight instrument

One, two or three bends in the shank of the instrument may be present to improve access by off setting the working tip

Instruments with the working tip in line

with the handle are most easy to use

Design of the handle is related to the purpose of the instrument

Light weight with small diameter handles used primarily for tactile and exploratory purposes. E.g. Probes

Heavier, with larger diameter handles are designed to transmit heavy pressure and which will be held for a longer time. E.g. scalers

Cutting instrument names Black classified all instruments by name

By 1) function e.g. scaler, excavator

By 2) manner of use e.g. hand condenser

By 3) design of the working end e.g. spoon excavator, sickle scaler

By 4) shape of the shank e.g. mon-angle, bin-angle, contra-angle

Combing all together, bin-angle spoon excavator

Cutting instrument Formulas Black also developed a numeric

formula to characterize the dimensions and angles of the working end

These help in identification and assistance in cataloging and ordering

Formulas are placed on the handle using a code of three or four numbers separated by dashes or spaces e.g. 10-8.5-8-14

1st number—indicates width of the blade or primary cutting edge in tenths of a millimeter (0.1) e.g. 10=1mm

2nd number—(of a four number code) indicates primary cutting edge angle…measured from a line parallel to the long axis of the instrument handle in clockwise centigrade

Angle expressed as a percent of 360 degrees e.g. 85% x 360 degrees = 306 degrees

Instrument is positioned so the number always exceeds 50

If edge is locally perpendicular to the blade then this number is normally omitted, resulting in a three-number code

3rd number (second number of a three-number code)—indicates blade length in millimeters e.g. 8=8mm

4th number—indicates blade angle, relative to the long axis of the handle in clockwise centigrade, e.g. 14 = 50 degrees

The instrument is positioned so that this number is always 50 or less

In some instances, an additional number is present along with the formula number on the handle

It is simply to assist the specific manufacturer in caloging and ordering

Using hand instruments

1) Pen grip Most frequently used

Middle and ring fingers used for support

Allows fine controlled movements with light or heavy touch

2) Palm grip

Instrument held between thumb and forefinger

Handle lies across the palm and clasped by remaining fingers

Thumb used for support

Greater control than with pen grip when using on maxillary teeth, providing heavier force over a limited range of movement

3) Finger grip Modification of palm grip

Of limited value

Used when palm grip fails to give correct line of access

REMEMBER ! All instrumentation must be

accompanied by finger or thumb support upon adjacent firm structures, commonly, crowns of the adjacent healthy teeth

Thumb and third or fourth fingers of the hand holding the instrument most commonly used for rest

Provides for accuracy in fine movements, and safety in forceful manipulations

INSTRUMENTS USED FOR EXAMINING THE MOUTH AND TEETH

1) MOUTH MIRRORS

• Vary in size

• Flat mirrors most commonly preferred and used

• Two main types are:-

A) Front-surface reflecting

• Produce a clearer image particularly at angles

• Most widely used

• Easily scratched

• Care required during cleaning and sterilization

B) Rear-surface reflecting

• Reflective surface beneath the glass so image seen through the thickness of glass twice

• Hence, produces a double image

• However, resistant to damage due to glass surface

• FUNCTIONS

• Retraction of tongue and cheek

• View areas not visible by direct vision

• Reflect operating light to dark areas

2) PROBES

• Mainly used for diagnoses with care taken by the operator

• Types and functions :-

• A) straight probe (actually bent)

• Checks the margin of restoration

• Examination of caries in dentine during cavity preperation

• Helpful if sharp

• B) Briault probe

• Sharp probe

• Easy access to enamel-dentine junction during cavity preparation

• For detection of subgingival calculus

• 3) periodontal probe

• Blunt with small ball at the end

• Marked with graduations to measure depth of periodontal pockets

• May measure the width of a tooth when a temporary crown is to be fitted

• Other types are:- CPITN and FURCATION

SCALERS

Used for removing supra and subgingival calculus and other deposits from teeth

Useful for removing temporary crowns

INSTRUMENTS FOR CUTTING TEETH AND REMOVING CARIES1) EXCAVATORS

Have discoid or ovoid blade

With margin bevelled to a sharp cutting edge

Functions:-

For removing soft dentine

Removing temporary fillings

For placing lining with its back surface (blade)

Sometimes for carving amalgam

2) CHISELS Straight and angled chisels are used

for splitting off unsupported enamel

Gingival margin trimmer is a double ended instrument with curved blades and a sloping cutting edge

Used to trim margins of small cavities adjacent to other teeth where access for rotary instruments is limited

3) HATCHETS AND HOES Similar to chisels in design and

function

Always angled or contra-angled

Hatchets—cutting edge is in the plane of the shank (like and exe)

Hoe—cutting edge lies in an axis at right angles to the shank

INSTRUMENTS USED FOR PLACING & CONDENSING RESTORATIVE MATERIAL1) PLASTIC INSTRUMENT

Stainless steel material for general use

Teflon coated or titanium nitride for composite use. Prevents sticking of the material & not scratched by composite filler particles

Flat blades—used for conveying and shaping materials which do not involve the use of particularly heavy pressure

Round ends—used for pushing materials into cavities and for shaping and burnishing

Heated for use with certain materials like wax

2) CONDENSERS OR PLUGGERS

Used for compressing and forming filling materials, particularly amalgam

Used with heavy pressure

Variety of shapes and sizes available for use in different situations

End may be smooth or indented

Smooth version preferred as indented may become clogged with old amalgam

3)CARVING AND FINISHING INTRUMENTS

Used for carving materials by cutting or scraping

Have sharp or semi-sharp blades of various shapes which is very important

Also important is their smoothness

MAINTAINING HAND INSTRUMENTS SHARPENING HAND INSTRUMENTS

Instruments will only cut properly if they are sharp

Steel instruments with bevelled edges, like chisels, can be sharpened on a small flat sharpening stone OR on a mounted stone in a hand piece

Light machine oil used as a lubricant

Instrument held to produce a 30-45 degree bevel

A fine edge initially cuts better but rapidly becomes better

Alternatively, fine abrasive disc can be used which are ideal for probes, excavators and scalers

Light pressure used with no lubricant

Over heating must be avoided

This removes metal rapidly and gives coarser finish to the edge, but has the advantage of speed

Tungsten carbide instruments retain their sharpness for much longer than steel instruments, but when they become blunt, they have to be returned to the manufacturer for sharpening

STERLIZING HAND INSTRUMENTS

Stainless steel, tungsten carbide and Teflon-coated instruments can be autoclaved

Carbon steel instruments, if autoclaved and left in a wet condition, will corrode

Hence, it is ideal to autoclave them in a post-vacuum autoclave

This leaves the contents dry at the end of the cycle