Dental Materials Chapters review for Mid term

Historical development of dental materials

No evidence of restorative dentistry existed until

Around 600-300 BCE

Silver paste first mentioned by

The Chinese 659 CE

18000 produced in France

FLuroide

First mentioned fluoride in 1874

G.V. Black developed the

First viable amalgam formula

In 1930 ADA established guidelines for testing

CONSUMER PRODUCTS

Awarded its first seal of acceptance in 1931

U.S food and drug administration

Medical devices grouped by the control needed to assure their safety and efficacy

Classifications of dental materials

Preventative/therapeutic materials, restorative materials and Auxiliary materials

Why do we manipulate materials the way that we do

We must 1st understand the challenges of the oral environment and \*\*there are Limitations of what can and cannot be used safely that varies from patient to patient

what is the normal mastication forces on the occlusal surface of molar teeth

Average 90 to 200 pounds per square inch

And can increase as much as 28,000 pounds per square on a cusp tip

Denture wearers apply how much force

Apply 40% less force than patients with intact dentitions

Stress

The internal force which resists the applied force

If the stress within an object cannot resist the force then

Distortion or deformation occurs

Strain

The distortion or deformation produced by stress

Is the amount of change that the force has produced in the object

Microscopic flaws occur until the material fails, resulting in fracture is called

Fatigue failure

Normal pH of saliva

6\.2 to 7.0

What is the desirable solubility of materials

Materials should have a low solubility

Gold and porcelain are retained in the oral environment for many years because of their insolubility nature

Effects of moisture

Water sorption

The ability to absorb moisture which can result in staining or slight enlargement of material

Example dentures placed in water over night tend to absorb some of the water and swell slightly

Metals tend to suffer from effects of moisture and acidity with the exception of gold and noble metals the deterioration of metals is called

Corrosion- deterioration or dissolution of the metal to a chemical attack or electrochemical reaction with other metals

Tarnish- discoloration as a result of oxidation of metal surfaces

What is Galvanism

Phenomenon of electric current being tansmitted between two dissimilar metals

The current may result in stimulation to the pulp

All forms of matter expand when they are heated and contract when cooled is called

Dimensional change

Excessive expansion of a restoration within a tooth may result in

The fracture of cusp and excess contraction may result in leakage of fluids and bacteria into open gaps resulting in sensitivity

What is the measurement of change in volume or length in relationship to change in temperature

Coefficient of Thermal expansion CTE

Percolation is

Repeated shrinkage and expansion of materials within a tooth which can open gaps in the interface between a restoration and the tooth

Which allows an ingress of bacteria and oral fluids which may lead to recurrent caries, staining and pulpal irritation

Thermal conductivity

the rate at which heat flows through a material over time

ENAMEL AND DENTIN ARE POOR THERMAL CONDUCTORS

METALS ARE EXCELLENT CONDUCTORS OF HEAT

Insulators used with metal to protect the tooth include ZOE and calcium hydroxide

Retention

Is the materials ability to maintain its position without displacement under stress

Mechanical retention

Involves the use of undercuts or other projections into which the material is locked in place

REQUIRES THE REMOVAL OF MORE TOOTH STRUCTURE

Chemical retention

Involves both adhesion and bonding

Adhere chemically to the bonding material then placed.. tooth surface is prepared with an acid etch to create microscopic pores in enamel and dentin

Combo of btoh

Wettability is based on the contact angle between the liquid and the tooth surface,, which you need a

Low contact angle the better the liquid adhesive spreads onto the surface of the tooth

Viscosity

Is the materials ability to flow,

You do not want material with high viscosity because it will not flow well

What is film thickness

The minimum thickness possible is important when using dental cement because if the thickness is too great than the crown will not seat properly

Surface energy for successful retention

You want High surface energy for good wetting,

When the enamel is etched a high surface energy is created that can attract liquids across the surface

What is the surface between the walls of the tooth structure and the restoration called

Interface

What is microleakage

If the tooth/restoration interface is not sealed there may be a space into which liquids and microorganisms can penetrate

It is the seepage of harmful materials

The biocompatibility of materials

Must benefit the patient and short-term/long-term factors must be considered

\*Some materials may be therapeutic in small quantities or if in contact with tissues for short periods of time, but may be irritating or toxic with longer contact or larger dose

What is the dominant color

Tooth colors are predominantly seen in yellow and brown range

HUE

The intensity or strength of a color

Chroma

How light or dark a color is

Value

The color of teeth is determined by the amount of light that passes through them

Transparent, opaque, translucent, vitality

Light passes easily through a tooth

Transparent

Light is completely absorbed

Opaque

A combination of light absorbed and light passed through

Translucent

What does it mean that colors look different under different light sources

Metamerism

What contains 700 microorganisms in the mouth, most of the bacteria in this are harmless unless the oral conditions change

Biofilm, dental plaque

Which quickly reforms after dental cleanings and on new placed restorations

Materials must

Be biocompatible, exhibit long term clinical durability, be esthetically acceptable

The allied oral health care practitioner must have an

Understanding of the limitation as well as the criteria for selection of materials

All chemicals are capable of producing harmful effects if not handled correctly.. therefore safety is the

Shared commitment of the dental team

Dust that can be generated during the manipulation of dry, powdered materials is

Particulate matter

Gypsum, alginate, microblasting materials and pumice

What is pneumoconiosis

A fibrotic lung disease that can be caused by chronic exposure to the dusts generated in the manipulation of dental materials

What protects occupational transmission of Blood borne pathogens standard

OSHA and Canadian center for occupational heath CCOH

Infection control guidelines is managed by

CDC

Chemicals shown to cause a physical or health hazard, Hazardous chemicals can:

Catch fire, react or explode when mixed and be corrosive or toxic

What is a bioareosol

A could-like mist containing microbes such as bacteria, viruses, molds, fungi, and yeast.

What are the precautions when working with mercury

➢Work in a well-ventilated space

➢Avoid direct skin contact with mercury

➢Avoid inhaling mercury vapor

➢Store mercury in unbreakable, tightly sealed containers away from heat

➢When preparing amalgam for restorations, use preloaded capsules

➢Reassemble amalgam capsules immediately after dispensing the amalgam mass

➢Clean spills using appropriate procedures and equipment

Acute chemical toxicity

High levels of exposure over a short time

Symptoms include irritation, nausea, dizziness, vomiting, headache and fainting

Chronic chemical toxicity

Repeated exposure, usually at lower doses, over a much longer time (months or even years)

➢The effects can include cancer, neurologic deficits, and infertility.

Inhalation protection

Masks worn during patient care may or may not provide adequate protection when working with chemicals

Flammable or combustible

Ignitable

Highly acidic or basic

Corrosive

Unstable or explosive

Reactive

Contains arsenic, barium, chromium, mercury, lead, silver, or certain pesticides

Toxic

What should a spill kit for mercury contain

Mercury absorbing powder, mercury sponges, and a disposal bag. A mask and utility type gloves should be worn

who must provide SDS’s

The manufacturers of the product, the office should obtain an SDS for every chemical used in the office

The hazard communication program contains

Chemical inventory

Written hazard communication program- identify by name all employees who have been exposed to chemical

Safety Data Sheets (SDSs)

➢Labeling of chemical containers

Employee training

Labeling exemptions

What is the best method for preparing the tooth or restoration?

A slurry of pumice and water applied with a bristle brush or rubber cup

Strength of the bond, determined by the amount of force needed to break the two materials apart, which bond is typically stronger?

Enamel bond is typically stronger than dentinal bond

Enamel etching, reduces the enamel rods and opens porosities among the rods, what are the etching times of permanent teeth

20-30 seconds

Dentin etching 10 sec

Highly mineralized tooth surface etch time

60 seconds

primary enamel has

A prism pattern that is not well structure causing the etching time to be 60 sec

After Etching enamel what is the appearance

Frosty

What is it like for dentin etching

Left moist and glistening

What is the smear layer

Debris from cutting of tooth structure during cavity preparation

It is a layer of mostly hydroxyapatite and collagen, and may also contain bacteria, plaque, saliva and even blood it must be removed because it plugs the dentinal tubules and cannot be washed off with air-water spray

Dentin Etching with Phosphoric acid

Dissolves the smear layer and for dentin etching- only need a 10 second etch

**excess water is removed by a gentle stream of air, but dentin surface must be moist to keep the collagen fibrils fluffed up**

Resin tags

When resin is cured by a chemical process, or light-activation, it locks into the microscopic spaces and irregularities

what is the importance of resin tags

The tags secure the resin to the enamel and create a very strong bond

Dentin bonding resins

Primer is placed first and dried before curing, to remove the solvent and the remaining water

What is more important on dentin than enamel

Primer

What are three things that all bonding systems have in common

Acid etchant

Dentin primer

Bonding resin

Etch-and-rinse (TOTAL-ETCH)

Phosphoric acid etching of both enamel and dentin with a separate step that includes rinsing off the acid after the acid is rinsed off, the dentin is left slightly moist

Self-etch

No rinsing is needed

Does not use a separate etching procedure, the acid is contained in the resin primer

Universal adhesives

Uses a phosphate ester that allows them to bond to the tooth structure, ceramics and metals

Very versatile

What are the three modes of curing used for resin bonding agents

Light-cure process

Self-cure process

Dual-care process

bonding systems are placed in two general categories

Total-etch (etch and rinse)

Self-etch ( no rinse)

Important preventive measures for caries management are

Fluorides, Antibacterial mouth rinses and sealants

What is the accepted optimal level of fluoride in the drinking water

0\.7 mg/L parts per million ppm

What is consumption of too much fluoride

Fluorosis

what are highly acidic foods that contribute to loss of tooth mineral

Citrus fruits, sodas and wine

Medical condition causing erosion

Acid Reflux, anorexia and bulemia

What interferes with essential enzyme activity of bacteria

Fluoride, bacterial inhibitor

When Fluoride is combined with this it suppresses bacteria associated with dental caries, and what is the side effectes

Chlorhexidine gluconate (0.12%)

Sustantivity prolonged effect

Side effects- Brown stain on the teeth, tongue and composite restoration and bitter taste

What are the methods of delivery of fluoride

Dietary fluoride supplements - Tablets, droplets and Lozenges

In office fluoride applications- Gels and foams and varnish which lasts 1-3 days

Over the counter fluoride rinses which 10mL for 30-60 sec and wait 30 min to eat or drink

Toothpast

What is the lethal dose for children weighing 20 pounds

It is approx 700 to 1500 mg of sodium fluoride

What are the indications for sealants

Recommended for teeth with

Steep cuspal inclines UNCOALESED GROOVES

Deep, sticky fissures

Self-cured sealant

polymerizes to final set approximately 2 minutes from the start of mixing

light cured material is

The operator can manipulate the material at will

Requires a 20 sec application of the curing light

Unfilled sealants wear faster than

Filled sealants if placed properly, wear is not a big issur

Sealant placement

Requires attention to detail- isolation is KEY

Clean surface with pumice, etch enamel with 37% phosphoric acid, rinse with water, dry the enamel, bonding, place sealant and cure and wipe with gauze w

What is the oxygen-inhibited layer

It is the set of resin at its surface is inhibited by contact with oxygen, it will be wiped off with gauze or cotton roll it should be wiped off because any moisture on the tooth can result in failure of sealant

Acrylic resins are

Polymers that play an important role in prosthetics, especially removable appliances

What are elastic materials of impression materials

Hydrocolloids, polysulfides, silicone rubber materials, Polyethers and polyvinyl

What are inelastic materials (older materials)

Dental compound

Impression plaster

Zinc oxide Eugenol

Impression wax