oral health and prevention - unit 5

dental plaque in relation to dental caries

What are ameloblasts?

Enamel cells

What is the function of ameloblasts?

Pumps calcium and phosphate ions into the enamel, allowing hydroxyapatite crystals to fill in the matrix

What is the term when ameloblasts are laid down?

Incremental lines or Striae of Retzius

What do Incremental lines represent?

How the layers of enamel are laid.

• Lines are parallel to the dentoenamel junction (DEJ)

What are enamel rods also called?

Enamel prisms

What is the structural unit of enamel?

Enamel rods (enamel prisms)

What are enamel rods made of?

Tightly packed columns of hydroxyapatite

Where do enamel rods start and end?

They start at the dentin surface and end at the enamels outer surface

How are enamel rods positioned relative to the DEJ?

Perpendicular to DEJ (dentinoenamel junction)

What is the shape of enamel rods?

Prism-shaped

How do enamel rods contribute to teeth?

They help give enamel its strength

What percentage of enamel is inorganic matter?

96%

What is the DEJ?

The dentinoenamel junction, where dentin meets enamel.

• It is hypomineralized (enamel contains less minerals = is softer & weakened)

Where are fissures commonly found?

In the central grooves of molars

What is an enamel lamella?

A crack-like mark in enamel

Where can an enamel lamella extend from a fissure?

From the bottom of the fissure to the DEJ

Why can fissures increase the risk of tooth decay?

They can provide pathways for acids to reach deeper into the tooth

What are the 3 stages of caries development?

1. Demineralization

2. Incipient caries

3. Overt lesion

Define demineralization (decalcification)

The acids produced by bacterial plaque dissolve the calcium phosphate minerals of the tooth enamel or dentin

What acids are produced during demineralization?

• Lactic acid and formic acid - stronger

• Acetic, propionic, butyric – weaker

Define Incipient caries

Represents an area that may become a cavity

• White spot

• Explorer will not stick into this type of caries

Define Overt lesion

Enamel has been penetrated by acids.

• Enamel rods collapse due to lack of support

• Dentin usually decays

Define Recurrent/Secondary caries

A carious lesion occuring around a restoration

• Micro-leakage is suspected

• Radiograph needed to detect it

Define Rampant caries

When there is a widespead decay in the oral cavity over a short period of time

Define arrested caries

Previously diagnosed as a cavity, or an incipient lesion BUT never progressed, therefore no restoration required

• usually black/dark brown

Which tooth surfaces are most prone to caries? (3)

1. Pit and fissures (occlusal, facial, lingual)

2. Smooth surfaces (facial, lingual, interprox.)

3. Root surfaces (cementum - cervical caries)

What are the primary microorganisms that cause caries? (4)

Those that produce lots of lactic acid

• Streptococcus mutans

• Lactobacillus (cariogenic if high in #’s)

  • as well as Aciduric bacteria & Acidogenic bacteria

What are some causative factors affecting the process of decay? (2)

• Bacteria

• Carbohydrates (sugars)

Provides food sources streptococcus mutans and lactobacillus which results in excreting lactic acid

What are some protective factors affecting the process of decay?

• Adequate saliva flow

• Fluoride toothpaste 5000ppm, 2x/day

• Fluoride mouth rinses

• Professionally applied toothpaste

How does saliva help with the prevention & reversal of the caries process?

• Calcium & phosphate maintain level of calcium in plaque

• Proteins & lipids form protective pellicle

• Neutralizes acids (buffers/antibacterial substances)

• Clears carbohydrates and acids from mouth

How does Xerostomia increase the risk of caries?

This is a condition where less saliva is produced. Less saliva = higher risk of caries

High mineral content in saliva reduces risk of….?

Demineralization

Glycoproteins in saliva act to…..?

Lubricate and aid in swallowing

Proteins, bicarbonate, and phosphate in saliva help with…..?

Buffering the acids produced by bacteria

How does thick saliva affect caries susceptibility?

Less it is able to wash away carbohydrates = increases risk

How does thin saliva affect caries susceptibility?

Dilutes and removes acid more efficiently = decreases risk

What is the best predictor of future caries?

Past and recent caries history

• sidenote: measured by looking at the # of caries in the last 3 years

How long does it take for the highest amount of acid content in the mouth to occur after eating carbohydrates?

5-20 minutes

What is the normal pH for plaque?

6.2 - 7 (before eating)

At what plaque pH level will enamel start to decalcify?

below 5 - 5.5

As a Level II DA, how can you suspect the presence of caries?

• Look for chalky white lesions

• Look for gray-white spots around interproximal areas

• Look for darker gray spots around restorations

  • May be recurrent decay

What is “tactile sense”?

When DDS or DH use an explorer for detecting decay, the interpretation of what is felt is tactile sense

How do radiographs help in examining caries?

It allows the view of caries between teeth (mesial/distal) and under existing restorations

• Gray areas in interprox. areas represent caries processing

Why does a basic plaque record fail to help assign caries risk?

It only notes presence, not the specific types of bacteria that are active.

What is the main purpose of a plaque control record?

To measure a patient's efforts and effectiveness at home plaque removal.

What level of caries risk value does visible plaque contribute to?

A moderate risk value.

How does a DiagnoDent machine detect dental decay?

• It emits a laser beam into the tooth

• Decay causes an altered wavelength at the bottom of the fissure

• Producing a numerical reading

What is a major advantage of the DiagnoDent?

It can detect cavities smaller than the tip of a dental explorer

Name two advanced technologies listed for caries detection

• DiagnoDent

• Spectra Caries Detection Device