Oral Ana Lec #6

Development and Eruption of Human Dentition

M

Missing teeth (due to caries or other reasons)

F

Filled teeth (teeth that have been restored)

Anthropology

Studies human evolution, diversity, and biological characteristics, including dental anthropology, which examines teeth to understand human evolution, health, and diversity through micro and molecular analysis.

Paleontology

Focuses on life forms from past geological periods through fossils, including dinosaurs. It studies the development, calcification, and eruption of teeth in extinct species to understand their biology and evolution.

Development

Refers to the events and processes involved in the formation and growth of teeth.

Calcification

The process in which the organic framework of the tooth becomes hardened as calcium and phosphorus salts from the blood are deposited into the tooth structure. This process involves the delivery of these minerals through blood vessels to the developing tooth, leading to the formation of enamel and dentin. Paano tumigas ang ngipin dahil sa presence ng phosphorus salts at ibang minerals.

Eruption

The process by which a tooth moves towards the occlusal plane, becoming visible in the mouth as it emerges through the gum tissue. The initial phase, called emergence, occurs when the tooth starts to break through the gum tissue and move towards the occlusal surface.

Chronological Age

Determined from the actual day of birth, as recorded by the parents or documented in school records.

Developmental Age

Refers to the age determined by the stages of tooth development. This includes the anatomical, physiological, and pathological changes that occur as teeth form, mature, and eventually erupt.

Eruption Pattern

Refers to the position and development of both primary and secondary dentition as they emerge and align in the mouth.

Radiographic Assessment Pattern

Involves using X-rays to evaluate the calcification of tooth crowns and the development of roots, monitoring the progress of tooth development from initial formation to eruption. Calcifications of crowns and development of the root of an uninterrupted development of teeth.

Environmental Factors

Maternal nutrition during pregnancy can affect tooth development.

Endocrinopathies

May become evident in juveniles and influence dental development.

Fluoride Exposure

Excessive fluoride intake, such as from tap water, can impact dental health and may cause conditions like dental fluorosis.

6 Weeks of Intrauterine Life

Tooth development begins in the fetus during this early stage of pregnancy.

6 Months

The first deciduous teeth (baby teeth), particularly the first molars, start to erupt.

6 Years

The first permanent molars, commonly known as "six-year molars," typically emerge.

What holds the tooth in the bone?

Periodontal ligament.

[Growth and Development] Calcification

The process where calcium and phosphorus deposits harden the tooth structure.

⅔

of the root is formed, the tooth is ready to emerge through the gum tissue.

Emergence

Occurs when the tooth begins to break through the gum tissue and become visible in the mouth.

Constant Mastication

Regular chewing wears down the enamel over time. Eventually, the tooth will undergo exfoliation, where it is naturally lost and replaced by a permanent tooth.

Cemetery

In elderly individuals, various dental changes can occur, including enamel wear, tooth loss, and changes in tooth structure.

Endoderm

Gut and many internal organs such as small intestines and stomach. (Mga lamang loob).

Ectoderm

Epidermis, nervous system other tissues such as enamel.

Mesoderm

Muscle cells and other connective tissues such as the dentin. Where the dental sac belongs to and is developed from.

Primitive Oral Cavity (Stomodeum)

The initial structure in embryonic development that forms the early mouth.

Oral Ectoderm

The stratified squamous epithelium that lines the stomodeum.

Function of Oral Ectoderm

Forms the foundation for the development of the oral cavity and associated structures.

When discussing the internal cavity during embryonic development, we refer to the stomodeum, which is the primitive oral cavity that eventually develops into the mouth and its associated structures.

Stomodeum

The early embryonic structure that forms the precursor to the mouth and oral cavity. It is the initial depression in the embryonic ectoderm that eventually develops into the mature oral cavity.

Stomatognathic System

Refers to the entire system of the mouth and jaws, including the teeth, gums, oral cavity, and related structures involved in mastication, speech, and swallowing. The stomodeum is a developmental stage that contributes to the formation of the stomatognathic system but should not be confused with the fully developed stomatognathic system.

Formation of the Buccopharyngeal Membrane

The ectoderm (outer germ layer) contacts the endoderm (inner germ layer) of the foregut to form the buccopharyngeal membrane.

primitive oral cavity and the foregut

Around the 27th day of gestation, the buccopharyngeal membrane ruptures, establishing a connection between the ____ and the ____.

Connective tissue cells

Underlying the oral ectoderm induce the overlying ectoderm to start tooth development.

Ectomesenchymal cells

Consist of spindle-shaped cells separated by a gelatinous ground substance.

PRIMARY EPITHELIAL BAND

It is a continuous band of thickened epithelium formed in both the upper and lower jaws.

Horseshoe shape

A ____ corresponds to the position of the future dental arches.

Primary epithelial band

Where do the future dental arches come from?

Jaw

The primary epithelial band is the source from which the ___ develops.

Primary epithelial band

This band is created by the fusion of separate plates of thickened epithelium after 37 days of development.

37 days

Primary epithelial band is created by the fusion of separate plates of thickened epithelium after ____ of development.

1. Vestibular lamina

2. Dental lamina

Primary epithelial band gives rises to two lamina:

Primary epithelial band

Where does vestibular lamina originate from?

Ingrowth of the jaw vesicles

How did vestibular lamina form?

Creates the space between the buccal surface of the teeth, referred to as the vestibular space.

What is the function of vestibular lamina?

Gives rise to future teeth, including both deciduous and permanent teeth.

What is the function of dental lamina?

Dental lamina

Where does deciduous tooth primordia located at?

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3 phases of dental lamina

Furrow band or vestibular band

Other term for vestibular lamina

Vestibular lamina

is a horseshoe-shaped band of epithelial tissue that grows buccal (toward the cheek) to the dental lamina. Galing sa external portion ng dental lamina.

Mesenchyme

The vestibular lamina grows deeply into the _____ of the developing jaw, separating the lips and cheeks from the area where the tooth is forming.

Vestibular space

As it develops, the vestibular lamina thickens and becomes more defined, eventually forming the _____.

42-48 days/8 weeks

Dental lamina formation (20 teeth).

55-56 days

Bud stage, deciduous incisor canine & molar.

14 weeks

Bell stage for deciduous teeth, bud stage for permanent teeth

18 weeks

Dentin and functional ameloblast in deciduous teeth.

32 weeks

Dentin & functional ameloblast in permanent teeth.

Function of dental papilla

Cells of the dental papilla will develop into the tooth pulp and dentin.

Dental papilla

An area of ectomesenchymal condensation adjacent to the enamel organ.

Dental sac

An area of ectomesenchymal condensation surrounding both the tooth bud and the dental papilla.

Function of dental sac

Cells of the dental sac will form the cementum and periodontal ligament.

Shallow Invagination

The deep surface of the tooth bud forms a shallow indentation.

Outer Enamel Epithelium (OEE)

Cuboidal cells cover the outer convexity of the cap.

Inner Enamel Epithelium (IEE)

Columnar cells cover the inner concavity of the cap.

Stellate Reticulum

As more intercellular fluid accumulates, polygonal cells separate to form a network known as the ____.

Enamel Knot

A dense cluster of cells located in the center of the enamel organ.

Function of enamel knot

Projects towards the underlying dental papilla. It extends vertically to form the enamel cord, both of which disappear before enamel formation begins.

Dental Papilla

Develops into the dentin and shows active capillary budding and cell division.

Dental Sac

Important for the formation of cementum and the periodontal ligament.

Dental Follicle

It is associated with the pulp of the tooth.

Histodifferentiation

During this phase, cells of the dental organ begin to differentiate into specific forms and functions.

Morphodifferentiation

In this phase, the dental organ assumes the characteristic shape of the tooth. The shape and specific characteristics of the tooth become more defined.

Enamel Formation for essential condition

Dentin formation is critical for enamel formation. Enamel can only be laid down after dentin is formed.

Dentin

The pulp forms first, followed by dentin. Once ____ is established, enamel formation can occur.

Histodifferentiation

During this phase, cells in the dental organ differentiate into specific types, such as odontoblasts (which form dentin) and ameloblasts (which form enamel). Will know na if it will be an incisor, cuspid, premolar, or molar. They’ll get their functional assignment (WHETHER TO INCISE, TO SHEAR, TO TEAR, FOR MASTICATING).

Morphodifferentiation

The dental organ takes on the shape (ano itsura) of the future tooth, with the invagination of the epithelium deepening and the enamel organ assuming a bell shape.

Odontoblasts

Differentiated from mesenchymal cells, these cells are responsible for dentin formation.

Ameloblasts

Derived from the inner dental epithelium (IDE), these cells produce an enamel matrix opposite the dentin. Kailangan ang presence ng dentin para may enamel. Pulp muna, then dentin, then the enamel will be laid down. The future DEJ is outlined and forms a crown that is being established.

DEJ

will be formed during the bell stage.

Dentino-Enamel Junction (DEJ)

Established during this stage, outlining the future junction between dentin and enamel and determining the crown's form.

Outer dental epithelium

A single row of cuboidal cells is thrown into folds and contains blood vessels at late bell stage.

Stellate reticulum

There is increase in intracellular fluid and layer expands. The cells assume star shape with long processes that anastomose (means it branches out) with adjacent cells.

Stratum intermedium

• Several layers of squamous cells appear between stellate reticulum and inner dental epithelium and are called___.

• This layer is essential for enamel formation. It helps in calcification of enamel and is a reserve source for new ameloblasts.

Inner dental epithelium

This consists of a single layer of cells that differentiates into tall columnar cells, the ameloblasts. They have a hexagonal shape on the cross section and are 4u in diameter and 40u in height. These cells influence the underlying mesenchymal cells, which differentiates into Odontoblasts.

IEE

IDE

OEE

ODE

DENTAL PAPILLA

• It is the mesenchyme enclosed portion of the Dental organ.

• The peripheral cells under the influence of inner dental epithelium assume a cuboidal shape first & columnar later and are called Odontoblast, which produce dentin.

What forms the future DEJ

Membrana Performativa

What produces dentin

Odontoblasts

What do odontoblasts produce

Produce dentin.

What does it produce and where did it come from

Odontoblast

What does pulp consist of?

Odontoblast that produces dentin.

What forms the dentin

The pulp.

DENTAL SAC

Before formation of dental tissues begins, the dental sac shows a circular arrangement of its fibers and resembles a capsular structure. With the development of the root the fibers of the dental sac differentiates into the periodontal fibers that become embedded in the developing cementum and alveolar bone.

APPOSITION

• The tooth germ forms calcified tissues of the tooth, the enamel, the dentin and the cementum.

• There is a layer-like deposition of an extracellular matrix resulting in additive growth.

• There is regular and rhythmic deposition, which is incapable of further growth.

[FORMATION OF THE ROOT] Starting Point

The root begins to form after the dentin has reached the future cementoenamel junction.

Roles of Dental Organ and Dental Papilla

Both the dental organ and the dental papilla are involved in root formation.