Chapter 8: Embryology

What are the 3 stages of palate formation?

1) Formation of the primary palate 2) Formation of the secondary palate 3) Fusion of the palate

During the third week of development what three primary embryonic layers are formed?

1) ectoderm 2) mesoderm 3)endoderm

What are the 3 periods of prenatal development?

1) preimplantation 2) embryonic 3)fetal

How many chromosomes are in a sperm and egg?

23 chromosomes resulting in a total of 46 chromosomes

At what month does the face look human?

4 months

The tooth bud for the second molars form when after birth?

6 months

The buds for the third molars form when?

About 5 years

Enamel forming cells

Ameloblasts

During this stage ( 11th and 12th week) the cells differentiate and become specialized in a process called histodifferentiation.

Bell Stage

The beginning of development for each tooth is known as what?

Bud stage AKA "Initiation"

What are the three stages of growth periods?

Bud, cap, and bell.

When are the branchial arches formed?

By the end of the fourth week.

The process by which the structural outline formed during the growth stage is hardened by the deposit of calcium and other mineral salts.

Calcification

During this stage the cells of a tooth grow and increase in number.

Cap stage AKA "Proliferation"

Specialized, calcified connective tissue that covers the anatomic root of the tooth.

Cementum

Thickened band of oral epithelium that follows the curve of each developing arch.

Dental Lamina

Gingivae between the teeth; this will also form the pulp and dentin of the tooth

Dental Papilla

Connective tissue the envelopes the developing tooth

Dental Sac

Hard portion of the root that surrounds the pulp and is covered by enamel on the crown and by cementum on the root.

Dentin

What two things are formed during the Morphodifferentiate process and act as the blue prints for the developing tooth?

Dentinoenamel Junction ( DEJ) and the cementodentinal junction (CEJ)

The process in which the body adds new bone

Deposition

Why is the embryonic period the most critical?

Development begins in all major structures

An organism in the earliest stage of development

Embryo

Study of prenatal development through the stages before birth.

Embryology

This developmental period extends from the beginning of the second week to the end of the eighth week, and the new individual is known as an embryo.

Embryonic Period

What is the Prenatal Development period where the cells begin to proliferate, differentiate, and integrate?

Embryonic Period

Part of a developing tooth destined to produce enamel.

Enamel Organ

Process of Histodifferentiation

Epithelial Cells become ameloblasts Peripheral cells become odontoblasts Inner cells of the dental sac differentiate into cementoblasts

Movement of the tooth into the functional position in the oral cavity.

Eruption

The normal process by which primary teeth are lost as permanent teeth develop.

Exfoliation

This prenatal development period starts in the ninth week and lasts until birth. The fetus has distinguishable ears, arms, hands, legs, and feet. As well as finger and footprints. This period is of growth and maturation.

Fetal Period

During what week does the palate form?

Fifth week

A fault along a developmental groove on the occlusal surface that is cause by an incomplete or imperfect joining of the lobes during formation.

Fissure

When should women of childbearing age avoid teratogens?

From the time of their first missed menstrual period

The period from fertilization to birth, has an average duration of 9 months, from conception to birth, or 40 weeks from the last menstrual period.

Gestation

Odontogenesis is divided into what three periods?

Growth, calcification, and eruption.

What is another name for the second branchial arch?

Hyoid Arch

First teeth to shed

Mandibular Anterior

The process of joining the parents chromosomes is called what?

Meiosis

Bone changes that occur along the articulations (joints) of bones as they increase in size and shape and keep up with the growth of surrounding tissues.

Modeling

The basic shape and relative size of each tooth are established during what process?

Morphodifferentiate

Dentin forming cells

Odontoblasts

Cells that are responsible for new cell formation

Osteoblasts

Cells that are responsible for resorbing bone

Osteoclasts

This prenatal development period takes place in the first week. an ovum (egg) is penetrated by and united with a sperm during fertilization . This union forms a fertilized egg.

Perimplantation Period

When two developmental grooves cross each other forming a deep area

Pit

What maybe formed when a tooth has several cusps that fuse together to form a solid enamel covering for the occlusal surface of the tooth.

Pit and Fissures

Begins with conception

Pregnancy

Shelf that separates the oral and nasel cavities

Primary Palate

Growth and changes in the shape of existing bone.

Remodeling

The body's process of eliminating existing bone or hard tissue structure

Resorption

Final palate formed during the embryonic period

Secondary Palate

What is formed in the fourth week of development?

Stomodeum (primitive mouth) and primitive pharynx

Adverse environmental factors that inlcude infections, drugs, and exposure to radiation.

Teratogens

What does the third branchial arch form?

The body of the hyoid and the posterior of the tongue.

What happens in the fourth week of the embryonic period?

The face and its related tissues.

Enlargements produced by the formation of dental lamina

Tooth buds

True or False when a permanent tooth starts to erupt before the primary tooth is shed, problems in spacing arises?

True

True or false the eruption of the primary and permanent dentition takes place in chronological order?

True

The fusion of the hard and soft palates starts in week 9 and ends in weeks 12. This fusion creates what type of pattern?

Y-shaped pattern in the roof of the mouth

Another name for fertilized egg

Zygote

Disturbances at any stage of development may cause what?

abnormalities

How big if the embryo at the fifth week of development?

approximately 5mm

When is the sex of the baby established?

at conception

What does the first branchial arch form?

bones, muscles, and nerves of the face, lower lip, the muscles of mastication, and the anterior portion of the alveolar process of the mandible.

Cementum forming cells

cementoblasts

What can development disturbances be caused by?

genetic and environmental factors

When the embryo is 5 to 6 weeks old and the first signs of tooth development are occurring in the mandibular region, what are the first teeth to develop?

mandibular anteriors and maxillary anteriors

Another name for the first branchial arch

mandibular arch

Process of tooth formation

odontogenesis

What is the dominate future in facial development in the embryo at 1 month

overhanging forehead

What is the futures in the second month of facial development?

rapid growth of the nose and upper jaw. The lower jaw appears to lag behind.

What does the fetus look like in the third month when talking about facile development?

resembles a human, although the head is disproportionately large.

At what week have the primary teeth developed and the development of the permanent teeth have begun?

seventeenth week

The tooth bud for the first permanent molar forms at what week of fetal life?

seventeenth week

What do the fourth, fifth, and sixth branchial arches from?

structures of the lower throat, including the thyroid cartilage, and the muscles and nerves if the pharynx ad larynx.

What does the second branchial arch form?

styloid process, stapes of the ear, stylohyoid ligament, and part of the hyoid bone. Also forms the side and front of the neck and some muscles of facial expression

Permanent teeth that replace primary teeth are called what?

succedaneous teeth

After enamel has reached the future CEJ what develops?

the root or roots

In prenatal tooth development what is the genetic factor that is most often a matter of concern?

tooth and jaw size