Day 12 biochem and path

Question 1

dextrans

** formed from?

Answer 1

extracellular structural component of plaque that are Essential for cariogenicity of mutans and lactobacilli
** formed from surcrose by bacterial enzyme glycosyl transferases

Question 2

what are the 3 main types of bacteria associated with progressive caries thru dentin?

Answer 2

1) streptococci mutans**
2) lactobacillus
3) actinomyces viscosus

Question 3

demineralization occurs when the pH of mouth drops below?

Answer 3

5.5

Question 4

what is basic secretory unit of salivary glands? causes hyper or hypotonic saliva?

Answer 4

acini, secrete fluid between 6-7.0 pH… aka HYPO

* hypo bc ductal cells reabsorb sodium and chloride in exchange for potassium and bicarbinate

Question 5

mucous vs serous secretion

*para or sym cuase secertion?

Answer 5

*BOTH! but para has greatest effect

mucous

• subMD and subL gland
• glycoproteins
• lubricate

serous

• contains enzyme amylase (ptyalin) to split startch
• prevent calc formation
• statherin, proline* rich proteins

Question 6

vagotomy or atropine causes dry mouth why?

Answer 6

it inhibits saliva production (vagal stimulation increases saliva)
* atropine prevents the action of acetylcholine on secreting cells

Question 7

a maximum salivary flow rate of less than _____ is associated with high caries

Answer 7

0.7mL/min

Question 8

enamel hypoplasia vs enamel hypocalcification

Answer 8

enamel hypoplasia= defect in mineralization of DEVELOPING enamel metrix

• caused by low vit A, vit D or calcium
• perm or baby effected, brown, pitted

enamel hypocalcification= defect in the mineralization of FORMED enamel matirx

Question 9

tooth erosion in bulimic patients is due to?

Answer 9

solubility of hydroxyapatite

Question 10

1) ameloblasts produce ______ with 2) two protein components called?

Answer 10

1) enamel matrix
2) amelogenins and enamelins
- - amelogenins- low MW and ECM protein
- - found in very small amounts

Question 11

enamel is highly mineralized structure of approximately 95%?

Answer 11

hydroxyapatite crystals made of calcium and phosphate

Question 12

how if fluoride beneficial?

Answer 12

enamel is semipermeable which allows fluoride ions to be absorbed on hydroxyapatite crystals forming fluorapatite
*fluoroapatite has LOWER solubility

Question 13

why is enamel is harder than bone?

which part is the structural foundation of enamel?

Answer 13

hydroxyapatite crystals are larger and more firmly packed than bone; this packed crystals form KEYHOLE-SHAPED RODS called enamel PRISMS (form structural foundation)

Question 14

1) bacteria the initiate caries must have the ability to produce?
2) examples?

Answer 14

1) extracellular insoluble glucans
2) *dextrans and mutans are types of glucans and they are both POLYMERS of GLUCOSE
* fructans polymers of fructose

Question 15

dextrans, mutans and levans are synthesized from dietary?

Answer 15

sucrose

Question 16

4 common antimicrobial agents?

Answer 16

1) chlorhexidine- most effective bc longest lasting after use; antimicrobial and antigingivitis (Peridex)
2) stannous fluoride - anticaries only
3) phenolic compounds- antimicrobial and antigingivitis (listerine)
4) quaternary ammonium compounds- best for bad breath

Question 17

what is the major carcinogenic property of S. mutans?

Answer 17

its ability to produce the enzyme glucosyltransferase
* they also: adhere to tooth of susceptible host, produce lactic acid and polymeric substnce to keep acid in contact with tooth

Question 18

define pellicle

Answer 18

surface coating of salivary origin, which is primarily protein in nature

Question 19

what is the first, second and third to form for bacterial colonization of plaque?

Answer 19

formation of pellicle

1) streptococci (G+ cocci)
2) lactobacillus (G+ rods)
3) fusobacterium and bacteriodes (G- rod shaped)
3) actinomyces (filamentus types)

Question 20

what happens as plaque ages?

Answer 20

• changes from G+ to G-
• cocci decreases and filaments increase
• aerobic decreses and anaerobic increases

Question 21

composition of plaque vs calculus?

Answer 21

plaque
- 80% water and 20% solids (95% of which are bacteria)

calculus

• 70-90% inorganic (lots of Ca and Phosphorus)
• rest is organic and water

Question 22

what bacteria is associated with ANUG aka NUG?

Answer 22

• intermediate-sized spirochetes
• prevotalla intermedia
• fusobacterium species
• selenomonas species

Question 23

supragingival vs subgingival plaque

Answer 23

supragingival

• attached or tooth associated
• mostly G+ facultative anaerobic cocci

subgingival

• attached or loosely adherent with epithelium association
• G- anaerobic rods
• darker due to blood breakdown
• spirochetes (treponema species), fusobacteria

Question 24

progression from heathy gingival sulcus to gingivitis is associated with a shift towards G___ anaerobic rods

Answer 24

G-