Lecture 5 questions

Question 1

What happens when there are changes in the biofilm environment?

Answer 1

biofilm thickness, which leads to difficulty of diffusion thru biofilm and an O2 gradient develops. The deepest layer becomes completely anaerobic, and bacterial metabolism results in lactic acid –> cavities

Question 2

what is the ideal thickness of the oral biofilm?

Answer 2

.2 mm- .4 mm

Question 3

what are the types of plaque?

Answer 3

• supra gingival and subgingival
• crevicular fluid is protective but pathogens use it for food
• when you have gingival inflammation, blood vessels open up, and pathogens/bacteria feed off of it

Question 4

what are the 3 sources of matrix in biofilm?

Answer 4

dead bacterial cells, saliva, gingival exudate (gingival crevicular fluid)

Question 5

what is the backbone of biofilm?

Answer 5

exopolysaccharides

Question 6

what is the lower layer of biofilm?

Answer 6

dense with microbes, polysaccharides matrix, tight bound, steep diffusion gradient, low oxygen, pH here is very low and can cause caries

Question 7

what is the loose layer of biofilm?

Answer 7

irregular shape and extends into surroundings

Question 8

what is the fluid layer of biofilm?

Answer 8

stationary sublayer, in motion, nourishes the biofilm by molecular diffusion, the most transient organisms are here

Question 9

what is the structure of supra gingival plaque?

Answer 9

1. tower/mushroom are of low shear force (interproximals)
2. elongated colonies that oscillate area of high shear force (all facial surfaces)
3. gram + very fibrillary matrix with strep mutans, due to polysaccharides and sugar molecules that are super gluey and sticky
4. gram - very regular matrix that isn’t sticky, but just wants to look for food. the easier way to feed itself is to cause inflammation (With endotoxins and proteolytic enzymes)
5. plaque skeleton made up of mutans, and energy source are the gluey carbs

Question 10

what is the structure of sub gingival plaque?

Answer 10

1. we don’t know what it comes from, but its structure is similar to surpegingival plaque
2. closest to the tooth is a fibrillar matrix and closest to the gingival sulcus are more spirochetes and flagellated bacteria, and no matrix
3. theres a huge danger of transferring bacteria from pocket to pocket when probing
4. note: implants can’t be placed in a mouth with active periodontitis!!!

Question 11

what do we like biofilm?

Answer 11

• for defense thru bacterial enzymes in the inter-bacterial matrix
• protection from external changes
• transfer of info and genetic material