Instruments and Equipment - Operative

Hand Instrument Materials

• Carbon Steel - Hard but corrodes

• Stainless Steel - Dull and loses edges but does not corrode

• Carbide - Durable but brittle

Hand Instrument and Rotary Instrument Parts

Hand Instrument

• Handle/Shaft

• Shank

• Blade (Cutting)/Nib (Non-cutting)

Rotary Instrument

• Head

• Neck

• Shank

Instrument Formula

1. Width of blade in tenths of mm

2. Cutting edge angle in centigrade (sometimes skipped)

3. Length of blade in mm

4. Blade angle in centigrade

Mirror

• #2 (5/8” diameter)

• #4 (7/8” diameter)

• #5 (15/16” diameter)

Explorer

• #23 explorer

• #17 explorer

• Used to examine around tooth surfaces to look for cavitites

• Both images: Feel for smoothness of tooth, surfaces and assess, and quality of margin

Probe

• Periodontal probe (William’s Markings: 1, 2, 3, 5, 7, 8, 9, 10 mm)

• Probe (3, 6, 9, 12 mm)

• First picture: Perio: Measure periodontal pockets and assess gingival health. Operative: Measures pulpal floor depth and remaining marginal ridge (William’s Markings)

• Second picture: Also perio characteristics

Amalgam Carrier

• Has hollow tip and plunger

• Carries mixed amalgam to cavity preparation

Condensers

• 0/1 Plugger

• 1/2 Plugger

• Markley Plugger

• First two images: Condense amalgam into prep

• Last image: Condense amalgam into smaller preps (<1 mm)

Burnisher

• Examples are ball, acorn, and football burnishers

• Polishes surface of amalgam restoration

• Burnishes margins so they are flush with tooth surface

Forceps

• Typically used for holding articulating paper

• Also carries things to and from mouth

Tofflemire Retainers

• Holds matrix bands

• Clamps end of matrix band and tightens it around tooth

• Needed for interproximal restorations

Automatrix Tightening Tool

• Tightens matrix bands

Automatrix Snipper

• Cuts outer matrix band for removal

Composite Instruments

• All gold instruments

• 8A Composite

• Trico Composite

• Place, sculpt, contour dental composites

Cement Spatulas

• Spatula/Dycal

• Spatula/Blade

• Dycal end picks up med to transfer to tooth

• Blade transfers mixed cement to indirect restoration

Spoons

• Type of Excavator

• Removes carious dentin

• Curved blade has outer convexity, inner concavity

Hoe

• Type of excavator

• Forms line angles and planing tooth prep walls

Straight Chisel

• Cuts enamel

Wedelstaedt Chisel

• Curved binangle chisel

• Cuts enamel

Enamel Hatchet

• Break open teeth and smooth cavity walls

• Cuts enamel

Marginal Trimmer

• MT 29 (mesial edge)

• MT 28 (distal edge)

• Cuts and planes enamel walls and margins

Interproximal Carver

• Contour embrasures of restoration

Anatomical Carver

• Place initial tooth anatomy and grooves in amalgam or composite

Cleoid-Discoid

• 3/6 Cleoid-Discoid

• 4/5 Cleoid-Discoid

• Cleoid End: Placement of anatomy, removing excess amalgam

• Discoid end: Rounding marginal ridges, removing excess amalgam

Hollenback Carver

• Contour and carve surfaces of amalgam restoration and carve interproximal areas

Two types of grasps

• Pen grasp

• Palm-thumb grasp

Rubber Dam Clamps

• Keep rubber dam tight around tooth

Rubber Dam Forceps

• Tightens clamp

Rubber Dam Frame and Curved Iris Scissor

• Cut rubber dam after use

• Maintains borders of rubber dam in position and supports retraction of soft tissue

Rubber Dam Punch

• Punches holes in rubber dam to go around teeth

• Makes clean-cut holes in rubber dam

Rotary handpiece speeds

• Low speed - <12000 rpm

• Medium speed - 12000-200000 rpm

• High-speed - >200000 rpm

Dental Bur Types

• Round - Initial entry and caries removal

• Inverted cone - Provides undercuts

• Pear shape - Class 1 (gold foils and amalgam)

• Straight Fissure - Amalgam tooth prep

• Tapered Fissure - Indirect restoration, no undercuts

High-speed vs Low-speed handpieces

• Slow-speed - Latch-type

  • Removal of caries, refining a cavity prep wall, performing prophylaxis

• High-speed - Friction grip

  • Cavity prep and removal of tooth structure

Clearance Angle

• Angle of leading edge of cutting tool from surface being cut

Rake Angle

• Angle of tool contact perpendicular to surface

Carbide vs Diamond Burs

Carbide Burs

• Better end-cutting

• Produce low heat

• More blade edges per diameter

Diamond Burs

• Abrasive over blade-cutting

Coarse to Fine in Microns

Ultra Coarse (180) - Black

Super Coarse (150) - Blue

Coarse (130) - Green

Standard (110) - No Color

Fine (40) - Red

Extra-Fine (15) - Yellow

Ultra-Fine (10) - White

Hazards with Cutting Instruments

• Pulpal Precautions

• Soft-Tissue Precautions

• Eye Precautions

• Ear Precautions

• Inhalation Precautions

Enamel Composition

Inorganic matter (90%)

Organic matter (2%)

Water (8%)

Is enamel semipermeable?

Yes, it takes in acid, caries, remineralization, fluoride and bleach

What properties of enamel decrease with age?

• Acid solubility

• Pore volume

• Water content

• Permeability

What property should restorative material have?

Compatible wear, smoothness, and strength

Crystal Rod Head and Tail differ in what property?

• Solubility due to orientation

What do acid etchants due to enamel?

Removes a bit of enamel and allow resin monomer to bind

Dentin Structure and Composition

• Apatite crystals and collagen fibrils

• 50% inorganic

• 30% organic

• 20% water

Outer Dentin vs Inner Dentin

• Outer dentin has more intertubular dentin

• Has lesser and thinner tubules as well

• Dentin close to DEJ is 8x more permeable

Outline Form for Class I Prep

• Prep is centered on central groove

• Pits and grooves removed

• Smooth (no sharp angles)

Convenience Form for Class I Prep

Wide enough isthmus (to accept #0 condenser)

Resistance Form for Class I Prep

• Deep enough depth

• Marginal ridge is not compromised

• Making mesial and distal walls diverge (preserves strength of marginal ridges)

Retention Form for Class I Prep

• Concave walls

• Dovetail

Issues with acute and obtuse cavosurface margins

• Acute - Unsupported enamel rods

• Obtuse - Very thin amalgam that can fracture

Importance of placing bur along axis of tooth

Prevents floor of prep from reaching the pulp

People retire from dentistry because of what disorder?

Musculoskeletal Disorder

• 70% dental students by 3rd year

What is PSP?

Prolonged Static Posture

Ergonomics

Study of science involving efficient and safe use of tools by humans

What seating positions should right and left-handed operators generally sit?

Right - 8 to 12 o’clock position

Left - 12 to 4 o’clock position

Natural Operator Seating Position

• Feet flat on ground

• Hips higher than knees

• Chair tilted 15 degrees

• Neutral shoulder position with elbows at sides

• Reasonable shoulder range of motion

• Operator head should not tilt more than 20 degrees

• Use hips rather than wrist or waist

What should you do for maxillary teeth?

Place patient in supine position

What muscles does the Un-Twister target?

• Quadratus Lumborum

• Latissimus Dorsi

• Teres Major

• Triceps

3 P’s of Ergonomics

• Posture

• Positioning

• Periodic Stretching

Esthetic Materials for Class 5 Restorations

• Resin Composite

• Glass Ionomer

• Resin modified glass ionomer

• Compomer

Why are Class 5 Preps and Restorations common?

• They are deep gingivally

• Located in non-self-cleansing area gingival to height of contour

What is trituration?

Process of mixing amalgam

Things to know about amalgam

• Each condensed amalgam increment should fill 1/3 to ½ of prep depth

• Make sure to condense apically and laterally with 5-10 lb of pressure

• Use round end of cleoid along cavosurface margins perpendicular to tooth structure

Reasons for Rubber Dam Isolation

• Moisture Control

• Retraction

• Harm Prevention

• Increase operator efficiency

• Potentially improve properties of dental materials

Types of Rubber Dam Isolation

• Posterior Isolation - One tooth distal to treated tooth extending to contralateral canine

• Anterior Isolation - From premolar to premolar

• Single tooth Isolation - Only the tooth being treated

Order of Hole Punches

• Anchor Tooth

• Molar

• Premolar/Canine

• Upper Incisors

• Lower Incisors

What type of lubricant is used on rubber dams?

Water-soluble lubricant

Modeling Compound for Rubber Dam

• Low-fusing modeling compound used to secure retainer to tooth and prevent movement

Winged and Wingless Technique for Rubber Dams

• Winged Technique - Clamp and frame are simultaneously carried to patient’s mouth for placement

• Wingless Technique - Clamp placed on tooth first and dam is stretched over bow

Interproximal placement of dental dam

• Operator passes dam by stretching dam faciogingivally or linguogingivally with fingers

• Waxed floss passes through remaining contacts to tuck edges into gingival sulcus

Reasons for Tooth Preparations

• Destruction from carious lesion (old and current reason)

• Replacement/repair of existing restoration

• Tooth fracture

• Esthetic Reasons

• Prosthesis on adjacent teeth

• Preventative purposes

What is the purpose of lasers in diagnostics for dentistry?

• Fluoresces bacteria

• Can cause false positives

What is the purpose of light in diagnostics for dentistry?

• Use to find carious lesions and fractures

• High specificity but low sensitivity

What is the purpose of dye in diagnostics for dentistry?

• Stains less well-mineralized dentin

• Can lead to over-preparation and pulp exposure due to natural differences in collagen content

Challenge of radiographs

• Some cavities are overlooked

• Some radiolucencies are misdiagnosed

E1, E2, D1, D2, D3

In what scenario only would you still leave infected dentin in tooth

Only if patient is asymptomatic and it is located within 0.5 mm of pulp

Good instrument for removing infected dentin

• Large round burs on slow speed handpiece OR

• Ceramic round burs

What factors can affect pH in mouth?

• Diet

• Hygiene

• Saliva

Detection of Pits and Fissures (with study findings)

• Done visually

• Explorer (and stick) does not help

• Explorer has potential to transfer bacteria

• Sharp explorers can create enamel defects

• Explorers can make non-cavitated lesions cavitated

• Clean and dry teeth for color changes or shadowing

• Explorer should gently be used for tactile evaluation of surface texture

Best way to detect hidden caries

Clean and dry teeth