Lecture 7B

Question 1

List parts of the tooth made by ____ and characteristics of each

Answer 1

Bone Synthesized - Osteoblast (Transport Ca2+ ions and composed of mainly type I collagen)
Bone resorbed - Osteoclasts
Enamel - amEloblasts (Only calcified tissue that does not contain collagen) (Requires scaffolding protein class called amelogenins)
Dentin - oDontoblasts (Calcified over type I collagen fibers like bone)
Cementum - Cementoblasts (Calcified over type I collagen fibers like bone)

Question 2

What comprises the periodontium?

Answer 2

Gingiva, cementum, periodontal ligament, surrounding alveolar bone

Question 3

What causes dental carries and how?

Answer 3

Results from microbial fermentations that produce lactate by glycolysis from monosaccharides
These bacteria referred to as saccharolytic (sugar metabolizing)

Question 4

Difference between saccharolytic bacteria and asaccharolytic bacteria and which predominately is contained in oral microbiota?

Answer 4

Saccharolytic bacteria - Produce lactic acid and lowers pH (Associated with dental caries)
Asaccharolytic bacteria - Hydrolyze proteins and utilize amino acids for energy, produce ammonium and raises pH (Associated with periodontal disease)

Saccharolytic bacteria mainly in oral microbiota with major end product being lactic acid

Question 5

Difference between gram positive vs gram negative bacteria

Answer 5

Gram positive - Thick cell wall with no outer membrane (Contained in saliva or adhering to the oral mucosa)
Gram negative - Thin cell wall with outer membrane (Contained in teeth adherent bacterial biofilms called plaque)

Thick cell wall of gram positive allow them to tolerate low pH caused by lactic acid production which causes caries

Question 6

What are mucins?

Answer 6

Proteins covered with numerous saccharide (glycan) residues

Question 7

What does the gingival crevicular fluid contain and provide?

Answer 7

Contains proteins from serum (blood plasma protein which clotting has been inactivated)
Provides a sulcus that is richer in proteins than saliva creating an environment more suited for an asaccharolytic microbiota
Gingival sulcus contains lots of Ca ions

Question 8

What prevents caries from developing beneath the gingival sulcus?

Answer 8

Amino acids that are deaminated to ammonia by asaccharolytic fermentation accumulate enough ammonia to make the gingival sulcus alkaline and this high pH prevents caries

Question 9

What causes dental calculus?

Answer 9

The alkaline environment in the gingival sulcus precipitates calcium and phosphate ions from gingival crevicular fluid to cause dental calculus

Question 10

What causes mouth odor and accompanies what type of disease?

Answer 10

H2S (Hydrogen sulfide) are released along with ammonia when sulfur-containing amino acids (cysteine and methionine) are metabolized)
H2S is major contributor of oral malodor that often accompanies moderate to severe periodontal disease

Question 11

Amino acid composition of collagen

Answer 11

33% glycine
~30% Proline and hydroxyproline

Question 12

Basic order of collagen synthesis?

Answer 12

Procollagen in RER that then enters Golgi and secreted into ECM to form tropocollagen. Multiple tropocollagen forms collagen (Cross linking in ECM)

Question 13

Oral disorders related to collagen and mutation of what amino acid causes this?

Answer 13

Osteogenesis imperfecta - Fragile bones
Dentinogenesis imperfecta - opalescent or completely missing teeth

Mutations of glycine residues inhibit adequate triple helix formation

Question 14

Importance of Vitamin C in collagen (Also symptoms of ascorbate deficiency)

Answer 14

Vitamin C is utilized for hydroxylation of proline and lysine and is an antioxidant (reducing agent) that protects macromolecules from oxidative damage by neutralizing ROS.
Humans cannot synthesis ascorbate (vitamin C) due to the lack of L-gulonolactone oxidase

Antioxidant property of ascorbate is important extracellularly where it neutralizes the ROS from leukocytes during inflammation

Early symptom of ascorbate deficiency is the loss of gingival and periodontal membrane fibers accompanied by loosening of the teeth

Question 15

Where is keratin found and composed of?

Answer 15

Found in hair, wool, skin, horns, and fingernails and composed of a-helical polypeptides

Question 16

What cells in the mouth are said to be parakeratinized?

Answer 16

Parakeratinized (not fully keratinized) in the cells of the outer surface of the hard palate and gingival mucosa

Question 17

What are the hard tissues of the tooth and how is hardness related?

Answer 17

Hard tissues of the tooth are the enamel and dentin with the pulp not being hard tissue and does not demonstrate mineralization.
Related to the ability to form calcium salts (Makes it harder)

Question 18

What is the formula for hydroxyapatite and where is it found?

Answer 18

Formula is Ca10 (PO4)6 (OH)2 (Dimers of Ca5 (PO4)3 (OH)1
Mineral of enamel and dentin

Hydroxyapatite is very insoluble

Question 19

% of mineral and protein in enamel and dentin

Answer 19

Enamel is hardest substance in the body with 97% mineral and less than 1% protein
Dentin supports and protects and is 70% mineral and 30% protein

Question 20

What are enamelins and amelogenins and involved in what?

Answer 20

Substitutes for collagen (Organizing proteins) that will later mineralize to form enamel

Question 21

What is fluoroapatite and importance?

Answer 21

When OH groups of hydroxyapatite are replaced by fluoride to make it harder and stronger

Question 22

What is required for mineralization?

Answer 22

Requires the right environment including scaffolding proteins (like collagen), high concentration of ions and the processes are called nucleation

Question 23

Direction of mineralization for enamel vs dentin

Answer 23

Dentin mineralizes toward the pulp (inward) while enamel mineralizes toward the crown (outward)

Question 24

What is saliva composed of?

Answer 24

Supersaturated with calcium and phosphate ions and buffers at around pH 7

Question 25

Is anaerobic or aerobic bacteria bad for our teeth and at what pH does the enamel begin to dissolve?

Answer 25

We don’t want anaerobic bacteria since they exude acids such as lactic acid and at pH 5.5 is when we start to see demineralization

Question 26

Importance of proline-rich proteins and statherin?

Answer 26

Acidic proline-rich proteins will bind calcium with a strength which indicates that they may be important in maintaining the concentration of ionic calcium in saliva

Statherin is a protein that maintains high calcium level in saliva thereby preventing teeth from dissolving

Question 27

How does fluoride resist dental caries? Process behind demineralization?

Answer 27

Using fluoridated toothpaste creates a CaF2 smear layer that maintains a low fluoride release throughout the day.
Fluoride inhibits enolase which lowers bacterial metabolism resulting in lowered lactic acid excretion.

Protons diffuse into hydroxyapatite crystal to react with OH group to change the crystal into an amorphous calcium monohydrogen phosphate solid that slowly dissolves.
Ca10 (PO4)6 (OH)2 -> CaHPO4

Question 28

What does taking high levels of fluoride do to osteoporosis? How does fluoride inhibit gluconeogenesis and ROS elimination?

Answer 28

Inhibits osteoblast activity more than osteoclast activity which results in an increased frequency of bone fractures.

Inhibits gluconeogenesis by binding Mg2+ ions that activate fructose bisphosphate phosphatase and protein synthesis initiation.

Inhibit ROS elimination by binding iron, selenium, and molybdenum ions at the respective catalytic centers of catalase, peroxidase, and superoxide dismutase

Question 29

How does bone remodeling work?

Answer 29

Stress induced bony microcracks attract circulating WBCs (monocytes) that differentiate into osteoclasts which possesses an acidic compartment containing acidic, tissue-degrading enzymes secreted from lysosomes. When all the bond around a microcrack is removed, osteoclasts disappear and osteoblasts lay down new bone in response to the stresses.

**Enamel cannot be remodeled since new ameloblast cannot be generated (only present during tooth development)

Question 30

What is the most abundant mineral in the human body?

Answer 30

Calcium
They are retained in the ER or the sarcoplasmic reticulum in muscle

Question 31

What are the 3 major glands that secrete saliva along with what they secrete

Answer 31

Parotid - Composed of only acinar cells that secrete a serous (watery) fluid
Submandibular - Composed of clusters of epithelial-like cells, acinar cells secreting a serous (watery) fluid and tubular cells secreting a mucous (viscous) fluid
Sublingual - Same as submandibular

Question 32

Components of saliva and importance?

Answer 32

Water
Sodium chloride - electrolyte
Sodium bicarbonate - stabilize tooth surface
Mucin proteins (proteoglycans that mediates viscosity)
a-amylase - digests starch
Proline rich proteins
Calcium and phosphate for mineralization

Salivary glands also secrete ammonia which helps in buffering the acids and provides better protection from caries

Question 33

What is xerostomia?

Answer 33

Dryness of oral cavity due to loss of major salivary gland, persistent mouth-breathing from nasal allergies or sinus infections, or if tobacco smoking persists

Question 34

Where do chronic periodontitis first appear?

Answer 34

At the gingival sulcus where marginal gingiva becomes red, swells with loss of collagen, and bleeds on gentle probing

Question 35

Why is alcohol used in mouthwash? Alternative to alcohol mouthwashes?

Answer 35

They require 15-20% alcohol to maintain essential oil solubility but this results in an increased risk of oral cancer in longtime daily users

Chlorohexidine contains alcohol free but still has antiseptic properties

Question 36

Why is NSAIDs possibly important for dental reasons?

Answer 36

NSAIDs inhibit COX enzyme which catalyzes the formation of prostaglandins and thromboxanes. Some studies suggest that COX inhibitors might control chronic periodontitis

Question 37

Importance of Alkaline pH?

Answer 37

Alkaline pH neutralizes lactic acid from osteoclasts preventing dissolution of the mineral components of dentine.
Alkaline pH also activates alkaline phosphatases which play an important role in hard tissue formation

Question 38

How does MI-Paste work?

Answer 38

MI Paste delivers bio-available supercharged calcium, phosphate, and fluoride ions to the enamel to form calcium phosphate crystals. This helps maintain a state of supersaturation of calcium and phosphate at the tooth surface which depresses demineralization and enhances remineralization

Question 39

How does tooth whitening work?

Answer 39

Tooth whitener products release free oxygen that penetrates the tooth to reach the deep stains that lie inside the inner tooth layers. The oxygen reacts with stain particles to break the stain particle into small lighter color particles causing the teeth to become lighter in color.

Tooth whiteners use one of two chemical agents: carbamide peroxide (precursor to hydrogen peroxide) or hydrogen peroxide

Question 40

How is tooth sensitivity to temperature a side effect in bleaching?

Answer 40

Indication of possible pulp response to hydrogen peroxide that penetrates through the tooth hard tissue and reaches the pulp

Question 41

Coagulation cascade of how it starts and final common pathway

Answer 41

Intrinsic pathway is instigated when blood comes into physical contact with abnormal vessel wall. Factors in blood
Extrinsic pathway is initiated by tissue factors released from injured tissues.

Final common pathway:
Prothrombin converts to Thrombin which then converts Fibrinogen to Fibrin and activates factor 13 for cross-linked fibrin clots

Question 42

Importance of blood clotting (hemostasis) in dentistry?

Answer 42

Tooth extraction in an elderly individual can cause an embolism elsewhere in the body that can cause heart attack, stroke, pulmonary obstruction, or peripheral necrosis.

Have to be careful of people with hemophilia (excessive bleeding) or people on blood thinners.

Question 43

Drugs that reduce clot formation and drugs that promote clotting?

Answer 43

Reduce Clot formation:
-Heparin
-Coumadin
-Warfarin
-Aspirin
-Ibuprofen

Promote clotting:
-Epsilon-aminocaproic acid
-Tranexamic acid

Question 44

Hemostatic agents in dentistry examples and function?

Answer 44

Hemostatic agents (stops larger bleeding) used to stop hemorrhage from inflamed pulp and injured gingiva
Astringents (stops minor bleeding) are substances that tend to shrink or constrict body tissues

Zinc, Iron, and Aluminum salts are the best astringents used in dentistry

Question 45

Importance of aluminum chloride in dentistry and process of how

Answer 45

Used commonly in gingival retraction because of its ability to cause contraction and shrinkage of tissue (Can precipitate protein, constrict blood vessels, and extract fluid from tissues)
Aluminum compounds act as hemostatic agents and astringents

Question 46

Importance of Ferric subsulfate solution (Monsel’s solution) in hemostasis

Answer 46

The solution on an open wound results in agglutination of surface proteins (including small bleeding vessels) leading to quick and efficient hemostasis