List:

EMBRYOLOGY

1-Enumerate the derivatives of neural crest cells.

2- Enumerate the remnants of Meckel's cartilage

3-Enumerate the derivatives of the 1st branchial arch (mandibular arch)

Answers of Embryology1-Cartilage,Bone dentin, dermis, mesencyme of upper facial region Sensory cells, Schwan cells, neurons Mesodermal cores of the branchial arches that form lower facial region Pericytes, endothelial cells, fibroblasts of the blood vessel walls

2- anterior part form mental ossicles middle part form lingula and sphenomandibular ligament posterior part forms incus and malleus of middle ear

3- The mandible and maxilla The lower lip and part of the upper lip and cheek

All teeth, muscles of mastication Salivary glands, anterior 2/3 of the tongue Remnants of Meckel's cartilage (see question 2)

TOOTH DEVELOPMENT

1- Enumerate the stages of odontogenesis2- Eneumerate the function of inner dental epithelium4- State the functions of the dental sac.

5- State functions of epithelial root sheath of hertwig.

6- State functions of stellae reticulum.

7- State functions of the dental lamina.

8- Enumerate the hypoclacified areas in enamel.

9- Enumerate the epithelial cell layers forming the enamel organ in the lab

bell stage.

Answers of Tooth Development

1- Initiation stage of tooth developmentBud stage of tooth developmentCap stage of tooth developmentBell stage of tooth developmentApposition and maturation stages of tooth development (Late bell stage)

2- It allows differentiation of odontoblasts-transport of nutrient material from dental papilla to enamel organ - determine the future morphology of the Ab- It differentiate into Ab that lays down enamel matrix and helps its mineralization- root formation- shares in the formation of reduced dental epithelium- after enamel formation, it forms protective layer called 1ry enamel cuticle.

ERUPTION

1- Enumerate the theories of eruptive tooth movement2- Enumerate the etiological factors that delayed or disturbed

eruption.3- Enumerate the histological features in the PDL during the eruptive phase.

Answers of Eruption

1- Root formation theoryBone remodeling theoryDental follicle theoryPeriodontal ligament traction theoryVascular pressure theoryMolecular determinants theory

2-i- Mechanical interferences caused by:- Supernumerary teeth. - Crowding of the teeth. - Soft-tissue impaction. - Odontogenic tumors and cysts.

ii-Systemic factors caused by: - Endocrine deficiencies.- Nutritional deficiencies- Craniofacial dysostosis.- Hypo-thyroidism.- Hypo-pituitarism. iii-Congenital factors.

3- Ligament fibroblasts show frequent cell-to-cell contacts of both the adherens and gap junction types.

- The presence of contractile elements in the ligament fibroblasts. - Occurrence of structure called the fibronexus.- High rate of turn over

SHEDDING

1- Enumerate the factors determining the pattern and rate of deciduous teeth shedding:

Answers of Shedding

1-i- Genetic factors: ii- Local factors:

-Local pressure:-Masticatory forces:

ENAMEL

1- Enumerate the life history of ameloblasts( The stages of development of ameloblasts.

2- Enumerate the function of secretory ameloblasts.

3- Enumerate the function of the basal lamina over the immature enamel.

4- Enumerate the function of transitional ameloblasts.

5- Enumerate the possible structures that present on the enamel surface.

6- Enumerate the hypomineralized structures in enamel7- What do you know about the primary enamel cuticle?

Answers of Enamel

1- Differentiating stage (pre-secretory ameloblast).- Secretory stage.- Transitional stage.- Maturative stage.- Protective stage.

2- Synthesis, modulation and secretion of the extra cellular proteins.- Degradation of excess synthesized proteins. Degradation of reabsorbed enamel matrix.- Partial mineralization of secreted enamel matrix.

3- A mean for hemi-desmosome attachment.- Acts as filter and barrier.- Controls the influx and efflux of material during enamel maturation.

4- Down regulation of secretory activity for enamel matrix proteins.- Up regulation of secretory activity for enamel proteinase or

molecules that activate them.- Up regulation of degenerative enzymes and/or the contents of

lysosomal system.- Up regulation of secretory activity for proteins that are targeted to

reform the basal lamina.- Up regulation of synthetic activity for certain enzymes such as

calcium ATPase.

5- Rodless enamel (prismless , structureless or aprismatic enamel):- Perikymata: (Fig.5-11)- Afibrillar cementum:- Cracks:- Rod-end markings

6- Enamel tufts -Enamel lamellae-Incremintal lines of Retzius-Rod sheath-Neonatal lines-Short increments

DENTIN

1-Enumerate the theories of dentin sensitivity.2- Enumerate the different pattern of dentin mineralization with references to their sites.3- Mention the different types of dentine.

4- What is meant by Dead tract?

Answers of Dentin

1- Direct neural stimulation:

- Odontoblastic transduction theory:

- Fluid or hydrodynamic theory:

CEMENTUM

1- Enumerate the functions of cementum

Answers of Cementum

:-Cementum furnishes a medium for the attachment of collagen fibers

of the periodontal ligament to the alveolar bone. The continuous deposition of cementum is importance to keep the attachment apparatus intact.

-In the same time deposition of the cementum at the apical part of the root compensate the loss of tooth substance that may occur from the occlusal wear.

-Cementum serves as a major reparative tissue for root surfaces damage as fracture or resorption can be repaired by deposition of new cementum.

1- Enumerate with drawing the different types of pulp cells.

2- Enumerate the periodontal ligament cells & discuss one of them.

3- Enumerate the periodontal ligament fibers & give an account on the oxytalan fibers. 4- Mention the different types of non-keratinocytes and discuss one of

them.

5- Enumerate with drawing the different types of P.L. cells.

6- Mention the different types of dentin and discuss two of them.

7- Enumerate with drawings the different types of pulp cells.

Bone structure

1- Functions of bone.2- The primary factors that stimulate bone resorption through osteoclasts.

3- Types of bone.4- Incremental lines of bone (cement lines).

5- Age changes of the bone.

Answers of Bone structure

1- Functions of bone. a- Skeletal support of the body.b- Store for calcium and phosphate which may be mobilized according to needs of the body.c- Protection for the internal organs.d- Manufacturing for blood elements.

2- The primary factors that stimulate bone resorption through osteoclasts . include parathyroid hormone, vitamin D3, interleukin-1, interleukin-6, tumor necrosis factor A, and transforming growth factor-A, whereas calcitonin, transforming growth factor-B, estrogen and interferon-Y inhibit osteoclastic bone resorption.

3- Types of bone.Bone tissue mainly exists in three forms:

I. Lamellar bone.Compact bone and Spongy (cancellous) bone.

II. Non lamellar bone.Coarse fibered bone and Woven bone.

III. Bundle bone.

4- Incremental lines of bone (cement lines) . 1. Resting lines:

These are slightly undulated lines seen in decalcified and ground bone sections. In decalcified sections, stained with H & E, they show dark blue lines. They demonstrate the incremental pattern of bone formation.2. Reversal lines:

These are scalloped lines, which indicate the post osteoclastic activity occurring on the surface of bone undergoing resorption. After osteoclastic activity new bone is laid down by osteoblasts over the old bone. Both old bone and new bone are separated by a scalloped line which is the reversal line, with the convexity of this line, usually, is directed towards the old bone. 3. Faint line:

In decalcified sections stained with silver impregnation another faint black line could be seen which indicates the abrupt change in the direction of collagen fibers of each successive lamella.

5- Age changes of the bone. As a result of aging the following changes occur in the bone of the

alveolar process:a- Decrease in the water content of the bone that leads to is brittleness. b- The spongiosa shows thinning of its trabeculae and widening of the marrow spaces.c- The red bone marrow, in the marrow spaces of the spongiosa, will be transformed into fatty marrow, while in the condylar head, in the angle of the mandible and in the maxillary tuberosity it persists unchanged.d- Consequent to the proximal attrition of the teeth, the teeth will incline mesially resulting in distal sloping of the crest of the alveolar septa instead of being in a horizontal direction in young individuals. These changes are pronounced in the premolar and molar regions. e- With the loss of teeth the alveolar process is resorbed, this is because of the pressure exerted upon the bone through the gingiva since it now acts as an organ of mastication, so the following changes will appear:

- After loss of the teeth in the upper jaw, the floor of the maxillary sinus may come very close to the mouth cavity with only a very thin plate of bone separating the mucous membrane of the sinus from that of the mouth. - In the mandible, loss of the teeth is usually associated with change in the position of the mental foramen. The mental foramen comes to be closer to the upper border of the mandible and in extremist cases it opens on the upper border and beneath the gingiva, so producing a sensitive area.

Tempro mandibular joint

1- The tempro-mandibular ligament functions. 2- Synoviocytes. 3- The functions of synovial fluid.4- Types of nerve endings in TMJ.

Answers of Tempro mandibular joint

1- The tempro-mandibular ligament functions. - Collateral ligament, prevent lateral displacement of one joint and

medial displacement of the other.- The oblique components limit the amount of inferior displacement.- The horizontal component prevents the posterior displacement.

2- Synoviocytes. - Type (A): macrophage-like synoviocytes. They possess many

plasma membrane invaginations, and associated pinocytotic vesicles. Their cytoplasm contains numerous mitochondria and lysosomal elements and a prominent Golgi complex. They exhibit marked phagocytotic properties.

- Type (B): fibroblast-like synoviocytes. They contain many rough endoplasmic reticulu. They synthesize the hyaluronate found in synovial fluid.

3- The functions of synovial fluid:- Proteoglycan contents of synovial fluid responsible for a well- defined physical properties of viscosity, elasticity and plasticity, which are important for lubrication. So the efficiency of TMJ increases and the erosion is reduced.- Nourishment to the joint parts with no blood supply (the fibrous covering the articular surface and the middle part of the disk).- Clear metabolites arising from articular surfaces and disk. 4- Types of nerve endings in TMJ:

There are four types of nerve endings including Ruffini's corpuscles (type I), Pacini's corpuscles (type II), Golgi tendon organ (type III) and free nerve endings (type IV). Free nerve endings are the most abundant, with Ruffini's, Golgi, and Pacini's endings following in descending order.

Saliva & Salivary Glands

a- Functions of saliva.b- Types of secretory units.

c- Non secretory cells.d- Functions of myoepithelial cells .e- Functions of intercalated ducts.

f- Functions of the striated ducts.g- Functions of excretory ducts.h- Salivary glands according to their location.

h- Salivary glands according to the nature of secretion.

Answers of Saliva & Salivary Glands

a- Functions of saliva.1. Protection 2- Buffering action 3- Maintenance of tooth integrity4- Digestion5- Defense (antimicrobial action)6- Taste 7- Tissue repair

b- Types of secretory units.

I. Secretory cells:

1- Serous cells2- Mucous cellII- Duct system: 1- Secretory ducts

A- Intercalated Ducts:

B- Striated ducts:

2- Excretory ducts.

3- Main duct.

c- Non secretory cells.1- Myoepithelial cells

2- Oncocytes

d- Functions of myoepithelial cells . Accelerate the initial flow of saliva. Reduce luminal volume. Contribute to the secretory pressure. Support the underlying parenchyma and reduce back

permeation of fluid. Help salivary flow to overcome increase in peripheral

resistance, thereby increasing overall permeability.

e- Functions of intercalated ducts.

1- The cells of the proximal part of the duct have secretory function.2- They convey the secretion from the terminal secretory units to the

striated ducts.3- Lactoferrin (a protein having an antibacterial function) has been

localized in the cells of the intercalated duct. 4- They are capable of reabsorbing protein from the lumen5- They may proliferate and undergo differentiation to replace damaged

or dying cells in the end pieces and striated ducts.

f- Functions of the striated ducts.1- They modify the secretion passing through them that is why they are

called secretory cells.2- They actively reabsorb sodium and chloride ions and secrete

potassium and bicarbonate in the primary secretion, thus the secretion is changed from an isotonic or hypertonic to a hypotonic secretion, with low sodium and chloride and high potassium concentrations.

3- Lysosomes which have an antibacterial effect are localized in these ducts.

4- Striated ducts contain the enzyme kallikrein which affect the water and electrolyte balance.

5- Iodine concentration takes place in the striated ducts.6- Amylase enzyme is added from the serum to the saliva by the cells of

the striated ducts.7- Animal experiments prove that nerve and epidermal growth factors

are localized in the cells of striated ducts.

g- Functions of excretory ducts.1- They convey the salivary secretion towards the oral cavity.2- They have the ability to reabsorb sodium and secrete potassium and

bicarbonate.3- The ductal reabsorption of sodium and chlorides exceeds the

secretion of potassium and bicarbonate leading to hypotonic saliva.

h- Salivary glands according to their location.

A- Glands of oral vestibule:

i. Labial glands.ii. Buccal glands.iii. Parotid glands.

B- Glands of the oral cavity proper:1- Glands of the floor of the mouth :

i. Major and minor sublingual glands.ii. Submandibular gland.iii. Glossopalatine gland.

2- Glands of the tongue:i. Anterior lingual glands (Blandin Nuhn) only found in humans.ii. Posterior lingual glands including: Von Ebner and Weber gland.

3- Glands of the palate:i. Postrolateral part of the hard palate.ii. Soft palate.iii. Uvula.

i- Salivary glands according to the nature of secretion.A- Pure serous:

i. Adult human parotid gland.ii. Von Ebner salivary gland.

B- Pure mucous:a. Palatine glands.b. Glossopalatine glands.c. Weber glands.d. Minor sublingual glands.e. The anterior portion of the anterior lingual gland (Blandin

Nuhn).

C- Mixed glands:i. Mixed predominantly serous:

a. Parotid of the newborn.b. Submandibular gland.

ii. Mixed predominantly mucous:a. Major sublingual gland.b. Posterior portion of the anterior lingual gland (Blandin Nuhn).c. Buccal glands.d. Labial glands.

Maxillary sinus

The functions of The Maxillary Sinus.

Answers of Maxillary sinus

The functions of The Maxillary Sinus.The air sinuses in the skull are important in lightening the weight of the skull and enhancing the facio-cranial growth. It helps in absorbing shock and trauma. Maxillary sinus has an important role in:1- Warming and moistening inhaled air.2- Vocalization and phonation.3- Producing bactericidal lysozyme to the nasal cavity.4- Contributing in olfactory sense.5- Pressure dampening6- Heat insulation of the brain.

Oral Mucous Membrane1- Functions of the oral mucosa.2- Classification of the oral mucosa3- Criteria of the keratinocytes.

4- Criteria of the non keratinocytes in oral epithelium.

5- Types of nonkeratinocytes.6- The cellular elements found in the lamina propria of the oral mucosa .7- The types of gingival epithelium according to the behavior of keratin.

8- Function of gingival ligament.

9- The component of this ligament are:

10- Stages of Passive eruption. 11- Loosely attached oral mucosa.12- Types of tongue papillae.

Answers of Oral Mucous Membrane

1- Functions of the oral mucosa.a) Protection:

The oral mucosa separates and protects deeper tissues and organs in the oral region from the environment of the oral cavity. The oral mucosa shows a number of adaptations of the epithelium and the connective tissue to withstand the mechanical forces (compression, stretching, shearing and surface abrasion) applied to it during mastication. Furthermore, it provides a barrier to microorganisms, toxins and various antigens.

b) Sensation:The sensory function of the oral mucosa is important because it

provides considerable information about events within the oral cavity, whereas, the lips and tongue perceive stimuli outside the mouth. In the mouth, receptors respond to temperature, touch and pain; the tongue also has taste buds, which are not found anywhere else in the body. Certain receptors in the oral mucosa probably respond to the taste of water and signal the satisfaction of thirst. Reflexes such as swallowing, gagging, retching and salivation also are initiated by receptors in the oral mucosa.

c) Secretion:The major secretion associated with the oral mucosa is saliva,

produced by the major and minor salivary glands.

The saliva maintains a moist and lubricant surface of the oral mucosa. Also it provides a buffering action as well as secreting some antibodies. Sebaceous glands frequently are present in the oral mucosa but, their secretions are probably insignificant.

d) Thermal regulation:In some animals, such as dog, considerable body heat is dissipated

through the oral mucosa by panting; for these animals the mucosa plays a major role in the regulation of body temperature. However, the human oral mucosa plays practically no role in regulating body temperature.

2- Classification of the oral mucosa

Considerable structural variations are shown by oral mucosa in different regions. The three main types of mucosa could be identified according to their primary function, masticatory mucosa, lining mucosa and specialized mucosa.

I- Masticatory mucosa (Keratinized mucosa):During mastication some parts of the oral mucosa are subjected to

forces and pressure, these are a) Gingiva b) Mucous membrane covering the hard palate.

II- Lining mucosa (Non-keratinized mucosa):It present in areas not subjected to high levels of friction but must be

mobile and distensible. It serves a protective lining and subdivided into:

1. Firmly attached to the underlying muscles:a. Lip.b. Cheek.c. Inferior surface of the tongue.d. Soft palate.

2. Loosely attached to the underlying structures as bone, fascia or muscle:a. Alveolar mucosa.b. Vestibular fornix.c. Floor of the mouth.

III- Specialized mucosa:This is represented by the mucous membrane covering the dorsal

surface of the tongue. It is a highly specialized structure, because of the presence of different types of papillae, taste buds and lingual tonsils.

3- Criteria of the keratinocytes. a) Always present in sheets and attached to each other by one or more type of cellular junctions.b) The cytoplasm of these cells is stained with ordinary stain as H & E.c) Their cytoplasm contains characteristic tonofilaments.

4- Criteria of the non keratinocytes in oral epithelium.a) Appear as clear cells by ordinary H&E stain, they need special stains.b) Present as scattered cells and not in sheets.

c) A clear hallows around their nuclei.d) Their cytoplasm is free from tonofilaments.e) No cellular junctions.f) They do not play any role in synthesis of keratohyaline granules or

keratin.

5- Types of nonkeratinocytes.a) Pigment cells.b) Langerhan's cells.c) Merkel cells.d) Inflammatory cells.

6- The cellular elements found in the lamina propria of the oral mucosa .a) Synthetic cells: fibroblasts secreting fibers and ground substance and fat cells concerned with the synthesis and storage of fat.b) Defensive cells: they are macrophages, mast cells and variable numbers of inflammatory cells derived from circulating leucocytes.c) Undifferentiated mesenchymal cells.

7- The types of gingival epithelium according to the behavior of keratin.

a) Orthokeratinized epithelium: stratum corneum consists of flat tightly packed scales and the nuclei are completely absent. This type constitutes 15%. b) Pararkeratenized epithelium: the stratum corneum consists of flat horny scales, which retain pyknotic nuclei or remnants of nuclear material. This type constitutes 75%. c) Nonkeratenized epithelium: The stratum corneum is absent. This type accounts for about 10%. The sheltered areas of the gingiva are always non-keratinized, and these are the epithelial lining of the gingival sulcus and the epithelium of the col.

8- Function of gingival ligament.

Their main function is to provide support for the gingiva against the tooth and alveolar bone surface, resisting masticatory loads.

9- The component of this ligament are:

a) Dentogingival fibers; it is part of the periodontal ligament and it arise from the root surface above the alveolar crest and radiate to insert into the

lamina propria of the gingiva. The most superficial fibers lie beneath the sulcular epithelium. b) Circular fibers encircle each tooth within the marginal and interdental gingiva, some attach to cementum, some to alveolar bone, some cross interdentally to join the fiber group of adjacent tooth.c) Alveologingival fibers; run from the crest of the alveolar bone and interdental septum radiating coronally into the overlying lamina propria of the gingival. d) Dentoperiosteal fibers; occur only in labial, buccal and lingual gingiva. They arise from cementum and pass over the alveolar crest to insert into the periostium.e) Transseptal fibers pass horizontally from the root of one tooth, above the alveolar crest to be inserted into the root of the adjacent tooth. Such fibers provide an anatomical basis for linking all the teeth in the dentition. They have been implicated in the mechanism of mesial drift.f) Semicircular fibers emanate from cementum near the cemento-enamel junction, cross the free marginal gingiva, and insert into a similar position on the opposite side of the tooth.g) Transgingival fibers reinforce the circular and semicircular fibers. The fibers arise from the cervical cementum and extend into the marginal gingiva of the adjacent tooth, merging with the circular fibers.h) Interdental fibers pass through the coronal portion of the interdental gingiva in the buccolingual direction, connecting buccal and lingual papillae.

i) Vertical fibers arise in alveolar mucosa or attached gingival and pass coronally towards the marginal gingiva and interdental papilla.j) Longitudinal fibers extend for long distances within the free gingival, some possibly for the whole length of the arch.

10- Stages of Passive eruption. It has 4 stages where the first and the second stages considered normal and third and forth stages may be normal or pathologic.

First stage:- Occur in the primary teeth till one year before shedding and in the

permanent teeth till 20-30 years.- The coronal end of primary attachment epithelium present on the

enamel and the apical end on the cemento enamel junction.- The clinical crown is less than the anatomical crown.

Second stage:

- Occur till the age of 40 years or even later.- The coronal end is still on the enamel and the apical end on the

cementum.- The clinical crown is less than the anatomical crown.

Third stage:- It is a transient stage. - The coronal end present at the cemento enamel junction and the

apical end on the cementum. - The clinical crown equal to the anatomical crown.Fourth stage:- From 60 years or even later.- The coronal and the apical ends present on the cementum.- The clinical crown is longer than the anatomical crown.

11- Loosely attached oral mucosa.a) Alveolar mucosa.- It covers the outer surface of the alveolar bone and attached loosely

to the periostume.- Covered by stratified squamous non-keratinized epithelium.- C.T. papillae are short or even missing.- The collagen fibers of lamina propria are regularly interwoven.- Submucosa may contain small mixed salivary gland.- Elastic fibers are thin in lamina propria and thick in submucosa

b) Vestibular fornix.- It allows the free mobility of the lips and checks.- It permits the movement of lip & cheek, and covered by stratified

squamous non-keratinized epithelium. C.T. papillae are short and few.

- The labial frenum (median and lateral) is folds of mucousmembrane contain loose C.T. with no muscle fibers.

c) Floor of mouth.- It allows the free mobility of the tongue.- Covered by thin stratified squamous non-keratinized epithelium. - C.T. papillae are few and short. - Submucosa contains fat cells.- Sublingual and submandibular ducts are present near the covering

mucosa in the sublingual folds.

12- Types of tongue papillae.

a) The filiform papillae.- Found on the dorsal surface of tongue, as high, narrow conical

structures that arranged in parallel rows and near the post. 1/3 the rows become parallel to sulcus terminalis.

- The papilla is composed histologically from central core of C.T. covered by keratinized epithelium.

- The primary papilla sends up 1-2 secondary papillae, where theepithelium over them becomes hornified.

- This papilla dose not contains taste buds.

b) The fungiform papilla.- Present on the dorsal surface of tongue in between filiform papillae

and they are numerous at the tip of the tongue and its lateral border. - The papilla is mush room like, narrow at the base with smooth

rounded top.- Histologically it composed of central core of primary C.T. papilla

and covered by stratified squamous non-keratinized epithelium.- The secondary C.T. papillae make the blood vessels near to the

surface epithelium so this papilla appears red in color.- This papilla contains 1-2 taste buds at its lateral wall.

The papillae on the tip of the tongue responsible for sweet sensation.

The papillae on the lateral borders responsible for salt sensation.

Chorda tympani responsible for theses sensation.

c) The circumvallate papillae They are (7-12 in number) present on the dorsal surface of tongue

anterior to sulcus terminalis.

- They do not protrude above the surface of the tongue but embedded in the tongue and surrounded by deep trough, the taste buds located at the lateral wall of the papilla and also at the lateral wall of the trough.

- In the base of the trough the von Ebner salivary gland ducts open there.

- The papilla has narrow base and wide surface with central core ofC.T. which sends secondary C.T. papillae to the stratified squamous non-keratinized epithelium.● Circumvallate papillae responsible for the bitter sensation, by the

glossopharyngeal nerve.

d) The foliate papillae - They are ill developed in human (rudimentary ) but they are large in

some animals.- Present as sharp parallel clefts on the lateral sides and anterior to sulcus

terminalis.- These clefts are bordered by narrow folds of the mucous membrane

at which taste buds are found. The von Ebner salivary gland opens in the clefts of these papillae.

- Foliate papillae responsible for the Sour sensation by the glossopharyngeal nerve.