Cariogenic Oral Flora, Flora of the Dentinal Caries, and Bacterial Progression (Oral Microbiology)

Question 1

What is the ‘ecological plaque hypothesis’?

Answer 1

• Organisms associated with disease are associated with sounds sites but at low levels -> No caries
• Shift in balance of flora due to environment changes allow cariogenic bacteria to thrive -> Caries form
• Prevention: Inhibition of causative bacteria, removal of forces that drive selection of cariogenic bacteria

Question 2

What are two techniques for identifying oral microbiome?

Answer 2

Pyrosequencing -> expensive, labor intensive but IDs unclassified microbes

HOMIM -> Cheap, easy but only IDs common known species

Question 3

Describe the progression of caries:

Answer 3

• General streptococci are present on healthy teeth
• Streptococcus mutans are main bacteria in early caries
• Lactobacilli are main bacteria once caries reach dentine: once caries reaches dentine, lactobacilli species diversity increases

Question 4

Describe adaptive response by odontoblasts:

Answer 4

• Odontoblast processes deposit calcified matrix plugs in dentinal tubules in response to invading bacteria.
• Odontoblasts secrete reactionary dentine matrix in response to continued bacterial invasion.

Question 5

Describe pulp infection:

Answer 5

• Early: <1/3 surface area of pulp infected
• Established: 1/3-2/3 surface area of pulp infected
• Advanced: >2/3 surface area of pulp infected, but some intact tissue

Question 6

Describe pulp infection microbiology:

Answer 6

• Lactobacilli responsible for early infection.
• Once pulp is opened up, many other bacteria penetrate pulp.
• Lactobacilli is ABSENT in advanced infection.