HISTOLOGY OF SALIVARY GLANDS

Parotid: so-called watery serous saliva rich in amylase
Submandibular gland: more mucinous
Sublingual: viscous saliva

Parotid Gland:  The parotid is a serous secreting gland.

There are also fat cells in the parotid.

Submandibular Gland

This gland is serous and mucous secreting.

There are serous demilunes

This gland is more serous than mucous

Also fat cells

Sublingual Gland

Serous and mucous secreting

Serous cells in the form of demilunes on the mucous acini.

more mucous than serous cells

Minor Salivary Glands

Minor salivary glands are not found within gingiva and anterior part of the hard palate
Serous minor glands=von Ebner below the sulci of the circumvallate and folliate papillae of the tongue; palatine, glossopalatine glands are pure mucus; some lingual glands are also pure mucus

Functions

Protection: lubricant (glycoprotein); barrier against noxious stimuli; microbial toxins and minor traumas; washing non-adherent and acellular debris; calcium-binding proteins: formation of salivary pellicle
Buffering: bacteria require specific pH conditions; plaque microorganisms produce acids from sugars; phosphate ions and bicarbonate
Digestion: neutralizes esophageal contents, dilutes gastric chyme; forms food bolus; brakes starch
Taste: permits recognition of noxious substances; protein gustin necessary for growth and maturation of taste buds
Antimicrobial: lysozyme hydrolyzes cell walls of some bacteria; lactoferrin binds free iron and deprives bacteria of this essential element; IgA agglutinates microorganisms
Maintenance of tooth integrity: calcium and phosphate ions; ionic exchange with tooth surface
Tissue repair: bleeding time of oral tissues shorter than other tissues; resulting clot less solid than normal; remineralization

Cementum

Composition

a. Inorganic (50%)—calcium hydroxyapatite crystals.

b. Organic (50%)—water, proteins, and type I collagen.

c. Note: Compared to the other dental tissues, the composition of cementum is most similar to bone; however, unlike bone, cementum is avascular (i.e., no Haversian systems or other vessels are present).

Main function of cementum is to attach PDL fibers to the root surface.

Cementum is generally thickest at the root apex and in interradicular areas of multirooted 

Types of cementum

a. Acellular (primary) cementum

(1) A thin layer of cementum that surrounds the root, adjacent to the dentin.

(2) May be covered by a layer of cellular cementum, which most often occurs in the middle and apical root.

(3) It does not contain any cells.

b. Cellular (secondary) cementum

(1) A thicker, less-mineralized layer of cementum that is most prevalent along the apical root and in interradicular (furcal) areas of multirooted teeth.

(2) Contains cementocytes.

(3) Lacunae and canaliculi:

(a) Cementocytes (cementoblasts that become trapped in the extracellular matrix during cementogenesis) are observed in their entrapped spaces, known as lacunae.

(b) The processes of cementocytes extend through narrow channels called canaliculi.

(4) Microscopically, the best way to differentiate between acellular and cellular cementum is the presence of lacunae in cellular cementum.

Cap stage

The first signs of an arrangement of cells in the tooth bud occur in the cap stage. A small group of ectomesenchymal cells stops producing extracellular substances, which results in an aggregation of these cells called the dental papilla. At this point, the tooth bud grows around the ectomesenchymal aggregation, taking on the appearance of a cap, and becomes the enamel (or dental) organ. A condensation of ectomesenchymal cells called the dental follicle surrounds the enamel organ and limits the dental papilla. Eventually, the enamel organ will produce enamel, the dental papilla will produce dentin and pulp, and the dental follicle will produce all the supporting structures of a tooth

MANDIBULAR FIRST MOLAR

It is the first permanent tooth to erupt.

Facial Surface:- The lower first permanent molar has the widest mesiodistal diameter of all of the molar teeth. Three cusps cusps separated by developmental grooves make on the occlusal outline The mesiobuccal cusp is usually the widest of the cusps. The mesiobuccal cusp is generally considered the largest of the five cusps. The distal root is usually less curved than the mesial root.

Lingual: Three cusps make up the occlusal profile in this view: the mesiolingual, the distolingual, and the distal cusp which is somewhat lower in profile. The mesiobuccal cusp is usually the widest and highest of the three. A short lingual developmental groove separates the two lingual cusps

Proximal: The distinctive height of curvature seen in the cervical third of the buccal surface is called the cervical ridge. The mesial surface may be flat or concave in its cervical third . It is highly convex in its middle and occlusal thirds. The occlusal profile is marked by the mesiobuccal cusp, mesiolingual cusp, and the mesial marginal ridge that connects them. The mesial root is the broadest buccolingually of any of the lower molar roots. The distal surface of the crown is narrower buccolingually than the mesial surface. Three cusps are seen from the distal aspect: the distobuccal cusp, the distal cusp, and the distolingual cusp.

Occlusal There are five cusps. Of them, the mesiobuccal cusp is the largest, the distal cusp is the smallest. The two buccal grooves and the single lingual groove form the "Y" patern distinctive for this tooth

Roots :-The tooth has two roots, a mesial and a distal.

Contact Points; The mesial contact is centered buccolingually just below the marginal ridge. The distal contact is centered over the distal root, but is buccal to the center point of the distal marginal ridge.

Roots: Lower molars have mesial and distal roots. In the first, molar, the mesial root is the largest. It has a distal curvature. The distal root has little curvature and projects distally.

Types of dentitions:

1. Diphyodont. Teeth develop and erupt into their jaws in two generations of teeth. The term literally means two generations of teeth.

2. Monophyodont. a single generation of teeth.

3. Polyphyodont. Teeth develop a lifetime of generations of successional teeth

4. Homodont. all of the teeth in the jaw are alike. They differ from each other only in size.

5. Heterodont. There is distinctive classes of teeth that are regionally specialized.

MAXILLARY CENTRAL INCISORS

Viewed mesially or distally, a maxillary central incisor looks like a wedge, with the point of the wedge at the incisal (cutting) edge of the tooth.

Facial Surface- The mesial margin is nearly straight and meets the incisal edge at almost a 90° angle, but the distal margin meets the incisal edge in a curve. The incisal edge is straight, but the cervical margin is curved like a half moon. Two developmental grooves are on the facial surface.

Lingual Surface:- The lingual aspect presents a distinctive lingual fossa that is bordered by mesial and distal marginal ridges, the incisal edge, and the prominent cingulum at the gingival. Sometimes a deep pit, the lingual pit, is found in conjunction with a cingulum.

Incisal: The crown is roughly triangular in outline; the incisal edge is nearly a straight line, though slightly crescent shaped

Contact Points: The mesial contact point is just about at the incisal, owing to the very sharp mesial incisal angle. The distal contact point is located at the junction of the incisal third and the middle third.

Root Surface:-As with all anterior teeth, the root of the maxillary central incisor is single. This root is from one and one-fourth to one and one-half times the length of the crown. Usually, the apex of the root is inclined slightly distally.