ORAL PHYSIO LEC

Physiology of Teeth

The most prominent structures of the oral cavity

Physiology of Teeth

They have their own respective forms to facilitate their function, such as incision and trituration or chewing of food

incision

trituration

chewing of food

• Physiology of Teeth have their own respective forms to facilitate their function, such as:

● They incise and reduce food material during mastication

● They help sustain themselves in the dental arches by assisting in the development and protection of the tissues that support them.

Major functions in life of the human teeth:

PHYSIOLOGIC MESIAL DRIFTING

Physiologic drifting of the teeth

Homodont

● Same teeth

● Single type of dentition, similar in shape

● E.g., fishes, amphibians, reptiles

Heterodont

● Different teeth and morphology

● E.g., humans, dogs, and cats

Monophyodont

● One set of teeth

● E.g., crocodiles and reptiles

Diphyodont

● Two sets of dentition

● E.g., humans, dogs, cats

Polyphyodont

● Multiple sets/Several replacements of teeth

● E.g., sharks, fishes, whales

Triangle

Trapezoid

Rhomboid

GEOMETRIC CONCEPT OF CROWN OUTLINE

Triangle

● Mesial and distal aspects of the six anterior teeth for both maxilla and mandible

● Central incisors, lateral incisors, cuspids

Trapezoid

a. Longest uneven side towards occlusal or incisal surface:

● Labial/buccal and lingual aspects of all the teeth, both anterior and posterior

b. Shortest uneven side towards the occlusal:

● Mesial and distal aspects of all maxillary posterior teeth.

Rhomboid

Proximal surface of all mandibular posterior teeth

Crown

● It is covered in enamel

incisal ridge or edge

cusp

● Anterior teeth have an ______ or _____, while posterior teeth present ____

Incisal ridge or edge

● Found on central and lateral incisors

● Used to punch and cut food material during mastication

punch & cut food material during mastication

Incisal ridge or edge used to:

Canine

is the only anterior teeth that has a cusp

Single cusp

● The canine/cuspids is the only

anterior teeth that has a cusp

● To shear and tear the food

● To support the incisor and premolars

Two cusp

● Found on premolars or bicuspids

● To grind food

● To support the canine

3 or more cusp

● Found on molars

● To grind/triturate food

maxillary 1st molar

this molar has 5 cusps

Root

● Covered with cementum

● The length and number of roots depends on the size and function of the teeth

Cementum

the root is covered with ____

Periodontal fiber

sharpest fiber found in the cementum that holds the periodontal ligament in place

PCA (proximal contact area)

Positive contact relation mesially and distally of

one tooth with another while they are in their

respective positions in the dental arch.

● To prevent food impaction

● To keep food from packing between the teeth

● It stabilizes the dental arches by combining the anchorages of all the teeth in either arch and should be in positive contact with each other

Importance of PCA

a. Labial or Buccal aspects

b. Incisal or Occlusal aspects.

PCA can be observed from 2 aspects:

Interproximal Spaces

Triangular spaces formed by the proximal

surfaces in contact.

Interproximal spaces

Triangularly shaped spaces in between the

teeth normally filled with gums/gingival tissue

gums/gingival tissue

Interproximal surface is triangularly shaped spaces in between the teeth normally filled with _____

1-1.5mm

In interproximal spaces, normally there is a separation of _____ between enamel and alveolar bone.

spillways

Embrassures AKA

Embrassures

where the food passes through proximal contact area, so when the upper and lower teeth meet, then the food spills out

○ Makes a spillway as an escape for the

food during mastication prevent food

from being force out of the contact area

● Clinical significance of Embrassures

a. Labial or buccal and lingual interproximal

b. Incisal or occlusal

Kinds of embrasures:

1 mm

The curvature of the cervical line of most teeth

will be approximately ___ along the proximal

area, and is less distally than mesially

Periodontal Fibers/Ligaments

Another term is periodontal membrane.

● It is a dense connective tissue attaching the tooth to the alveolar bone

1-1.25mm

Thickness of periodontal fibers and ligaments

Sharpey’s fibers

—which are collagenous fibers that pass from the periodontium and are embedded in the circumferential area and interstitial lamellae part of the bone.

Formative and repair

Supportive and protective

Nutritive and sensory

Functions of the ligament:

● Branches of the alveolar artery

● Branches of the interradicular artery

● Gingival vessels that enter the periodontal ligament in the crestal region

Blood supply of PDL:

Contain both sensory and autonomous nerve endings

Nerves of PDL contains:

Nerves of PDL

Contain both sensory and autonomous nerve

endings

Transeptal fibers

Embedded into the cementum of adjacent teeth and extends interproximally over the alveolar crest

Alveolar crest fiber/Alveolar gingival fiber

Extends obliquely from the cementum

beneath the junctional epithelium to the

alveolar crest

Horizontal fibers

● Extends at the right angle to the long axis of the tooth between cementum and alveolar bone

● Right angle from the root of the tooth

Oblique fibers

The largest group of principal periodontal fibers, extending from the cementum obliquely to the alveolar bone

Most numerous among the fibers

Apical Fibers

• Radiates from the apical cementum to

the alveolar bone at the base of the

socket

● Found at the apex of the root

Interradicular Fibers

Courses over the crest of the

interradicular septum in the furcations

of multirooted teeth

Cementum

A mineralized connective tissue that covers the

entire root of the teeth

Attach PDL to the tooth

Main function of cementum:

45-50% inorganic and

50-55% organic content

○ Inorganic component: Hydroxyapatite

○ Organic component: type 1 collagen fibers

Composition of Cementum

Dental sac

Cementum forms from

Dentin

Cementum is lighter than ___

light yellow

Color of Cementum

Radicular Cementum

Coronal Cementum

Classification of cementum according to its

location:

Acellular Cementum

Cellular Cementum

Classification of cementum according to

cellularity:

Acellular Cementum

Also called primary cementum

Cellular Cementum

Also called secondary cementum

Fibrillar Cementum

Afibrillar Cementum

Classification of cementum according to presence or absence of collagen fibrils:

Fibrillar Cementum

Filled with matrix that contains well-defined fibers of collagen 1

Afibrillar Cementum

Devoid of fibers that covers the coronal half to the root of the tooth

AAC

● Cementum that lacks both cells and

collagen fibers.

● It is a thin, structureless layer primarily

composed of mineralized matrix.

AAC

● Location: This type of cementum is typically found on the enamel surface near the cementoenamel junction (CEJ)

AEFC

• Type of cementum that contains collagen fibers, primarily extrinsic Sharpey's fibers, but lacks cementocytes (cells).

● It is a thin layer (5-10 micrometer) that

extends to the coronal of the root

consisting of mineralized matrix from

fibers of the periodontium

AEFC

typically found on the cervical two-thirds of the root and is involved in anchoring the tooth to the alveolar bone via the periodontal ligament.

CMFC

Cellular mixed fiber cementum is

characterized by the presence of both

extrinsic and intrinsic fibers, along with

cementocytes (cells).

CMFC

● Location: This type of cementum is

generally found on the apical 1/3 of the

root and in furcation areas (areas

between the roots of multi-rooted teeth).

CIFC

Cellular intrinsic fiber cementum

contains intrinsic fibers and

cementocytes but lacks extrinsic

Sharpey's fibers.

CIFC

usually found in

areas of repair on the root surface,

particularly after resorption.

Cementoblasts

• The cuboidal cells found between the

fibers at the surface of the cementum

● Cell forming

● It builds and creates new cementum

● It becomes cementocytes once it loses its power

Cementoclasts

● Multi-giant cells similar to osteoclasts

● Cell destroying

Cementocytes

Are cementoblasts that are cell-enclosed in the self-generated matrix

Enamel Projections

● Found on maxillary first molars but can sometimes be found on mandibular molars

Enamel Projections

Enamel extensions that stick out from

the tooth crown into the root area

Hypercementosis

Excessive thickening of the tooth’s root

due to too much cementum into the root

area

Hypercementosis

Non-neoplastic deposition is excessive

cementum attached to the bone

Enamel Pearls

Developmental anomalies found on the cervical or the root portion of maxillary molars but can also be found on mandibular molars

0.3-0.4mm

diameter of enamel pearls

Cementicles

• Globular masses of acellular cementum

● They are round nodules found on the

periodontal ligament

Cementoma

● Benign tumor of cementum

● Appears on the apex of the root of the

tooth

● They are radiolucent in appearance

● Can be converted to radiopaque during terminal stage of the case

● Can cause pain or tooth movement if it becomes large

Alveolar Process

• Part of maxilla and mandible that forms and supports the teeth

● The bone structure

● Alveolar socket = the space

Alveolar bone proper

Consists of thin lamellae of bone

surrounding the root of the tooth called

lamina dura

lamina dura

thin lamellae of bone surrounding the root of the tooth called ____

Supporting Bone

Bone that surround the alveolar bone

proper and provides additional

functional support

Osteoblasts

● Bone-forming cells

● Builds and form new bone tissue

Osteocytes

Mature bone cells derived from

osteoblasts that maintain and nourish

the bone

Osteoclasts

Bone-destroying cells

Pulp

• Loose connective tissue consisting of five components: nerves, blood vessels, fibers, cells, ground substances

● Formative organ of the tooth

Formative

Nutritive

Sensory

Defensive

Function of Pulp

Fibroblast

Odontoblast

Defensive cells

Cells found in the pulp:

Gingiva

Another term is "gums," and it is the outer

covering of the oral mucosa

● Covers the bone and alveolar process

Free gingiva

Marginal gingiva/unattached gingiva AKA

Marginal gingiva/unattached gingiva

● Border of the gingiva surrounding the

teeth in a collar-like fashion

● Normally, the size is about 2-3 mm

● Shallow crevices around the tooth

bounded by the tooth surface and the

epithelial lining

Attached gingiva

It is firm, resilient, and tightly bound to

the underlying alveolar periosteum

(mucoperiosteum)

Interdental Papilla

It occupies the interproximal space

between the areas of adjacent tooth

contact

Oral Epithelium

● The outer epithelium

● Covers the outer surface of marginal

gingiva and some surface of the

attached gingiva

Sulcular epithelium

● Lines the gingival sulcus

● Thin keratinized squamous cell that can be found on the junctional epithelium to the crest of the gingival margin