Anatomy - Midterm Learning Objectives 1-6 Flashcards
1.1 Explain directional terms.
Directional terms are used to explain exactly where various body structures are located relative to each other. Such terms are precise and avoid the use of unnecessary words.
Superior - above another part, or closer to head
Inferior - below another part, or closer to feet
Proximal - Closer to a point of attachment, or closer to trunk of body
Distal - Farther from a point of attachment, or father from trunk of body
Lateral - The side, or away from midline
Medial - Toward, or nearer the midline
Dorsal - on the back
ventral - on the front
Anterior - toward the front
posterior - Toward the back
1.2 Differentiate between the anatomical and clinical structures of a tooth.
The anatomical crown is the whole crown of the tooth, whether it has erupted or not.
The clinical crown is part of the tooth that can be seen in the mouth
1.3 Identify and locate the different tissues of a tooth.
Enamel - forms outer surface of anatomical crown, thickest at the tip of crown & becomes thinner until it ends at cervical line, hardest tissue in the human body
Dentinoenamel junction - line marking the junction of the dentin and enamel
Dentin - forms the main portion or body of the tooth, hard, dense calcified tissue, softer than enamel but harder than cementum or bone, is capable of continuous formation
Cementum - a calcified substance that covers the root of the tooth, the main function is to provide a means for the attachment of the tooth to the alveolar bone, denser than bone but not as dense as dentin or enamel, least calcified tooth tissue, thinner at cervical line, thicker at apex of the root
Dentinocemental Junction - the line indicating where the dentin joins the cementum
Pulp - nourishing, sensory, and dentin reparative system of the tooth, composed of blood vessels, lymph vessels, connective tissues, nerve tissues & odonotoblasts, housed in the center of tooth, surrounded by dentin, only sensation pulp responds to is pain
Pulp chamber - housed in the coronal portion of the tooth
Pulp canal - located within the roots
Pulp cavity - pulp chamber & canal are referred to as this
Pulp horn - the tissue which extends towards the cusps or incisal corners
Odontoblasts - special dentin formation cells
1.4 Explain the function of each type of tooth.
Incisors - with their sharp biting edge, are designed to cut. The lingual side is shovel shaped to guide food into the mouth
Cuspids - crown of cuspid is more massive than that of an incisor; also have the longest root out of all teeth. They are placed in corners of the mouth and are designed for holding & grasping.
Premolars/Bicuspids - Located posterior to the cuspids, these teeth have two cusps to help hold or grasp pieces of food but they also have a broader surface used to pulverize or grind food.
Molars - These teeth have several cusps which provide a broad working surface and interlock with the opposing teeth to pulverize or grind food.
1.5 Identify and locate surfaces, divisions, and angles of a tooth.
-Each tooth has 5 surfaces total
-lingual - tongue side
-palatal - upper lingual side
-facial surface - the surface of a tooth faces the cheek or lip
-labial surface - outer
surface of anterior teeth
-buccal surface - outer surface of a posterior tooth
-proximal surface - surface of tooth that faces the neighbouring tooth’s surface
-mesial surface - surface closest to midline
-distal surface - surface facing away from the midline
-The lingual and buccal surfaces of a tooth are divided into - mesial, middle, and distal third.
-The mesial and distal surfaces of a tooth are divided into - a facial, a middle, and a lingual third.
-The buccal and lingual surfaces of a posterior tooth can also be divided into an occlusal, middle, and cervical third.
-The labial and lingual surface of an anterior tooth can be divided into an incisal, middle, and cervical third.
-The root of a tooth can be divided transversally into an apical, middle, and cervical third.
Line Angle - separates two surfaces of a tooth by forming the junction of the two surfaces. (ex. Distolabial, linguoincisal, mesiobuccal, bucco-occlusal)
Point Angle - a point at which three surfaces meet (disto/mesial > facial surface > incisal/occlusal)
1.6 Identify and locate the anatomical landmarks of the teeth.
Contact Areas:
- adjacent teeth touch each other at their widest points. This is known as the contact area.
-Prevents food from packing between teeth & injuring supporting structures/gingival tissue.
-Supports the teeth in place in the dental arch.
-Protects the interproximal gingiva from trauma during mastication - Generally located in the incisal 1/3 of the anterior teeth.
- Contact area of molars are generally located in the middle 1/3 of the crown
Tooth contour - All teeth have curved surfaces, some surfaces are convex and some are concave. The shape or contour of the tooth deflects the food mass onto the gingival tissues at a specific and proper angle to protect the tissues from damage.
Height of contour - refers to the widest point on a specific surface of the crown of a tooth. The contact areas on the mesial and distal surfaces are the height of contour on the proximal surfaces.
Interproximal space - the area or space between adjacent tooth surfaces. The interproximal space is filled with gingival tissue.
Embrasures - the v-shaped space between the proximal surface of two teeth in contact in the arch. Named according to the direction they face. The interdental papilla fills the apical embrasure.
Cusp - mound on the crown portion of a tooth that makes up a major division of its occlusal surface. Found on cuspids, bicuspid, and molars.
Tubercle – small “cusp-like” elevation on some portion of a tooth, or crown, usually on the lingual surface.
Cusp of Carabelli - Extra cusp on the mesial-lingual surface of the upper first permanent molar
Cingulum - a bulge of enamel found on the cervical third of the lingual surface of anterior teeth
Mamelon - Rounded prominence on the incisal edge of newly erupted incisors (wears off)
Groove - Channel (or hollow) made to direct motion or to receive a corresponding ridge.
Development Groove or Primary Groove - Sharp deep V-shaped depression that marks the junction between the development lobes of teeth
Fissure - Is a fault along a developmental groove on the occlusal surface. It is caused by the incomplete joining of the lobes of teeth during tooth development
Pit - small pinpoint depression where 2 or more grooves meet
Fossa - * depression or concavity * area on the tooth that is indented
* named by location (lingual fossa, central fossa)
Ridge - Linear surface on tooth
Cusp Ridge - * inclined surface or ridges that form an angle at the cusp tip when viewed from the buccal or lingual aspect
Marginal Ridge - linear elevation that forms the mesial and distal shoulders of the occlusal surface and the mesial and distal shoulders of the lingual surface of anterior teeth
Transverse Ridge - union of two triangular ridges, a buccal and lingual, that cross the occlusal surface of a posterior tooth (ML – MB or DL – DB)
Triangular Ridge - the main ridges on each cusp that run from the tip of the cusp to the central part of the occlusal surface
Oblique Ridge - a ridge on Mx molars that crosses the occlusal surface from the distobuccal cusp to the mesiolingual cusp.
1.7 Identify and locate structures of the oral cavity - PART 1
The vermillion zone (area) - redish full part of the lip
vermillion border - is the line of demarcation between the vermillion zone and the skin of the face
philtrum - skin of the upper lip has an indentation extending from the area below the middle of the nose to the center of the upper lip
nasolabial sulcus - is a shallow depression extending from the corner of the nose to the corner of the mouth.
labio-mental groove - is a shallow linear depression between the center of the lower lip and chin
labio-marginal sulcus - refers to the shallow depression extending downward from the corners of the mouth.
Commissure - refers to the corner of the mouth.
Boundaries of the Oral Cavity - The oral cavity is the area extending from the lips posteriorly to the area of the palatine tonsils, commonly referred to as “the tonsils”
Mucous membrane - lines the oral cavity. This soft, pink, moist tissue is called the oral mucosa and occurs in varying thicknesses
Masticatory Mucosa - covers areas subject to stress
Specialized Mucosa - covers the area that has the specific function of taste
Lining Mucosa - covers all other areas of the oral cavity
Palate - or roof of the mouth defines the superior border while the tongue and floor of the mouth is the inferior boundary.
tonsillar pillars - palatine tonsils lie on the sides of the throat between two folds of tissue
oral fissure - opening of the oral cavity to the exterior
fauces - opening of oral cavity into the pharynx
vestibule - is the space between the lips or cheeks and the teeth.
The oral cavity proper - is the area from the teeth back to the oro-pharynx
-mucobuccal or mucolabial fold - is the point at which the mucosa of the cheeks or lips turns to go towards the “gums”.
mucogingival junction - is the point at which the mucosa becomes tightly attached to the alveolar bone and is the beginning of the gingiva.
frenum - is a narrow fold of mucous membrane passing from a more fixed to a moveable part (buccal is by cuspids - labial is midline)
If the maxillary labial frenum is too firm for the erupting central incisors to penetrate, they may be pushed aside so space would exist. This space is known as a diastema
sebaceous glands - They appear as yellowish granular structures embedded in the skin (inner lips) and are called Fordyce’s spots or granules. They may also be found on the buccal mucosa.
Parotid or Stenson’s gland/Parotid papilla - a small, raised flap of tissue on the buccal mucosa opposite the upper second molar. It is often marked with a tiny red dot which is the opening to salivary gland
Linea alba - is a raised, white horizontal extension of soft tissue along the buccal mucosa at the occlusal line
maxillary tuberosity - a small, rounded extension of bone, covered with soft tissue, is found posterior to the last maxillary tooth
retromolar area - is a triangular area of bone, covered with soft tissue, posterior to the last mandibular tooth
Exostoses - are small bony growths on the buccal cortical plate of the vestibule
mandibular tori - bony growth under tongue
bony eminence - is the raised contour of bone, covered with soft tissue, that follows the roots of the teeth, in particular, the canine eminence
gingiva - Surrounding the necks of the teeth and covering the bone in which the teeth are anchored is a pink, stippled mucosa
1.7 Identify and locate structures of the oral cavity - PART 2
Hard Palate - The hard palate serves as the bony roof of the mouth and separates it from the nasal cavity
rugae - are transverse ridges of tissue found in the anterior portion of the hard palate
palatine raphe - a ridge of tissue running down the midline of the palate
fovea palatinus - Two small indentations, one on either side of the raphe located at the junction of the hard & soft palate
incisive papilla - singular bulge of tissue at the mid-line immediately behind the maxillary central incisors
incisive canal (beneath incisive papilla) which carries a nerve to the soft tissue lingual to the maxillary anterior teeth, a point of injection for anesthetizing the palatal gingiva adjacent to the maxillary anterior teeth
torus palatinus - may be an excess bony growth in the midline of the hard palate
soft palate - The posterior third of the palate
uvula - the most posterior portion of soft palate at the mid-line is a downward projection known as the uvula
oropharynx/fauces - arch or entryway that joins the oral cavity with the pharynx,
pillars of fauces – two folds of tissue on either side, one behind, one in front of, the tonsils
palatopharyngeal arch or fold – a more prominent fold, behind the tonsil, also called the posterior pillar
palatoglossal arch or fold– immediately in front of the tonsil, also called the anterior pillar
palatine tonsils – masses of lymphoid tissue located between the anterior and posterior pillars of fauces
Lingual Frenum - Extending from an area near the tip of the tongue down to the floor of the mouth is a fold of tissue. If this frenum is attached close to the tongue and is rather short, the tongue will have limited movement. This condition is called ankyloglossia
Sublingual caruncle - At the base of the frenum, there is a small elevation on each side. This is the opening for salivary glands
Sublingual fold - Extending from the sublingual caruncle back along the floor of the mouth on either side of the mouth is a fold of tissue containing a number of small openings or ducts of the sublingual salivary gland
tongue - an epithelial sac filled with muscles
upper surface of tongue is dorsum
underside of tongue is ventral
median sulcus - midline depression in tongue
Circumvallate or vallate papillae - form a V-shaped row of circular raised papillae about two-thirds of the way back on the tongue
Fungiform papillae - appear as tiny, round, raised spots on the anterior two-thirds of the tongue
Filiform papillae - are tiny, pointed projections of epithelial tissue, covering the anterior two-thirds of the tongue. They have no taste function but provide tactile sensation
foliate papillae - on lateral side of tongue, well developed but do not contain taste buds
lingual tonsils - a region near the mid-line on the dorsum of the tongue, just behind the vallate papillae This is tissue similar to that of the palatine tonsils and provides a defense mechanism in that area
1.8 Apply dental numbering systems.
International - The F.D.I. (Federation Dentaire Internationale) Numbering System
Using this system, the first digit indicates the quadrant and the second digit indicates the tooth within the quadrant. The teeth are always numbered from the mid-line anterior teeth working towards the posterior teeth. In the permanent dentition, the quadrants are numbered 1 to 4 and the teeth are numbered from 1 to 8 in each quadrant.
The Universal Numbering System: The permanent teeth are numbered from 1 to 32 and the primary teeth are lettered from A to T. Therefore, each tooth has only one letter or one number and that letter or number always refers only to that specific tooth. Start counting with the maxillary right third molar (#1) and count around to the maxillary left third molar (#16). Then, drop down to the mandibular left third molar (#17) and count around to the mandibular right third molar (#32).
The Palmer Numbering System - Using this system, the mouth is also divided into quadrants. A symbol is used to indicate the quadrant (vertical and horizontal lines). In each quadrant, the teeth are identified from the midline to the posterior. An entire quadrant can be indicated by the use of the letter Q. The primary teeth are identified using capital letters from A to E. In the permanent dentition, the teeth are numbered from 1 to 8.
2.1 Identify the four levels of organization in the human body.
Level 1 - Cells
-Are the basic unit of structure and function in living things
Level 2 - Tissues
-Made up of cells that are similar in structure & function which work together to perform a specific activity (epithelial, connective, muscle, nerve)
Level 3 - Organs
-Made up of tissues that work together to perform a specific activity
Level 4 - Organ System
- Groups of two or more tissues that work together to perform a specific function for the organism.
Level 5 - Organisms
-Entire living things can carry out all basic life processes. Meaning they can take in materials, release energy from food, release wastes, grow, respond to the environment, and reproduce.
-Usually made up of organ systems, but an organism may be made up of only one cell such as bacteria or protozoa.
2.2 Explain the purpose of each body system.
Skeletal System - Protection, support, and shape
Muscular System - Holding body erect, locomotion, movement of body fluids, production of body heat, communication
Cardiovascular System - Respiratory, nutritive, excretory
Lymphatic & Immune Systems - Defence against disease
Nervous System - reception of stimuli, the transmission of messages
Respiratory System - Transport of oxygen cells, excretion of carbon dioxide, and some water wastes
Digestive System - Digestion of food, absorption of nutrients, eliminations of solid wastes
Urinary System - Formation and elimination of solid wastes
Integumentary Systems - Protection of the body, regulation of body temperature
Endocrine System - Integration of bodily functions, control of growth
Reproductive System - Production of new life
2.3 Identify disorders of body systems in relation to dental care.
Body System - Disorder - Dental Concern
Skeletal System - Arthritis, Fractures, Osteoporosis - May effect the bones of the mandible
Muscular System - Sprains, tension contusions, atrophy - May affect the muscles of the neck
Cardiovascular System - Endocarditis, pericarditis - It can be caused by bacteria as a result of a dental treatment
Lymphatic & Immune Systems - Swelling of lymph glands, compromised immune systems (lupus) - Swelling may affect the ability to swallow, lupus can cause mouth and lip sores as well as a burning sensation in the mouth.
Nervous System - MS, Parkinsons, Epilepsy - May cause tremors and seizures in patients affecting dental treatment procedures
Respiratory System - Pneumonia, Tuberculosis sinusitis, Pharyngitis - This may affect the patient’s ability to breath effectively or swallow
Digestive System - Reflux, Ulcers -May cause nutritional deficiencies in patients that affect oral structures
Integumentary System - Abscesses, Carcinomas - May be found in oral structures
Endocrine System - Diabetes, thyroid disorders - May cause nutritional deficiencies. Medications may affect oral structure.
2.4 Discuss the four primary groups of human tissue.
- Epithelial Tissue – covers and lines the external and internal body surfaces and serve as a protective covering or lining. They are also involved in tissue absorption, secretion, sensory and other specialized functions.
(Types - 1. Covering and lining & 2. Glandular or secretory / 1. Simple (single layer) & Stratified (more than 1 layer) & Pseudostratified (appear stratified, but are actually in a single layer) - Connective Tissue – is the most abundant type of basic tissue in the body. It is usually composed of cells spaced apart and large amounts of matrix between the cells. Connective tissue is involved in support, attachment, packing insulation, storage, transport, repair and defense.
- Muscle Tissue – part of the muscular system. They have the ability to lengthen and shorten which produces movement of body parts. (1. Smooth Muscle (involuntary), Striated (voluntary), heart (cardiac muscle))
- Nerve Tissue – forms the nervous system of the body. They are responsible for coordinating and controlling body activities. They carry messages or electrical impulses from all areas of the body to the brain and from the brain to various areas of the body.
*Tongue – has all 4 tissues
Epithelial – surface / protective cover
Connective Tissue – underneath – support and nourishment
Muscle Tissue – movement
Nerve Tissue – motor and sensory
3.1 Describe the three embryonic germ layers.
During the third week of development, the cells of the embryo form the three primary embryonic layers:
- Ectoderm (outer layer) → epithelium covering outside the body and lining the oral cavity, nasal cavity, sinuses, tooth enamel, and nervous system
- Mesoderm (middle layer) → skeletal system, muscles, blood, lymph, kidneys, and other internal organs
- Endoderm (inner layer) → epithelial lining of pharynx, stomach, intestines, lungs, bladder, urethra, vagina
3.2 Describe the stages of facial development.
Face begins forming during the 4th week of prenatal development.
All three embryonic layers are involved in facial development: ectoderm, mesoderm, and endoderm
- Stomodeum and oral cavity formation: Stomodeum (primitive mouth) appears as a shallow depression in the embryonic surface ectoderm at the cephalic end before the fourth week
- Mandibular arch and lower face formation: After the formation of the stomodeum, two bulges of tissue appear inferior to the primitive mouth, the two mandibular processes. These paired mandibular processes fuse at the midline to form the mandibular arch.
After fusion, the mandibular arch then extends as a band of tissue inferior to the stomodeum
The mandibular arch directly gives rise to the lower face, including the lower lip. - Frontonasal process and upper face formation: The frontonasal process forms as a bulge of tissue in the upper facial area.
On the outer surface of the embryo are placodes, which are rounded areas of specialized, thickened ectoderm found at the location of developing special sense organ (lens placodes & nasal placodes). The placodes become submerged, forming a depression in the center of each placode, the nasal pits. The middle part of the tissue growing around the nasal placodes appears as two crescent‑shaped swellings located between the nasal pits. These are the medial nasal processes. On the outer part of the nasal pits are two other crescent‑shaped swellings, the lateral nasal processes. - Maxillary process and midface formation: During the fourth week of prenatal development, an adjacent swelling forms from increased growth of the mandibular arch on each side of the stomodeum, the maxillary process. Each maxillary process will grow superiorly and anteriorly around the stomodeum. The upper lip is formed when each maxillary process fuses with each medial nasal process on both sides of the stomodeum due to the underlying growth of the mesenchyme The maxillary processes contribute to the sides of the upper lip, and the two medial nasal processes contribute to the philtrum.
3.2 Describe the stages of facial development - PART 2 Brachial Arches
Beneath the stomodeum, five paired branchial arches form, in the region of the future neck. These are designated as branchial arches I, II, III, IV, Immediately below the stomodeum is the first branchial arch, which will develop into
2 maxillary processes
2 mandibular processes
All parts of the oral and nasal cavities now develop from the frontal process and the first branchial arch (except for parts of the tongue).
Branchial Arch
Right and Left maxillary process
-Upper cheeks, sides of the upper lip and most of palate
Right and Left mandibular process
- Lower cheeks, lower lip, lower jaw, part of the tongue
3.3 Describe the developmental stages of oral cavity structures.
Development of Oral and Nasal Cavity - develop during the 4th to 12th week of prenatal development
Palate Development - formation of palate starts during the 5th week of prenatal development, within the embryonic period. Formed from 2 separate embryonic structures - Primary & secondary palate. Palate is completed later in 12th week (within the fetal period).
5-6th week - Primary Palate - Intermaxillary segment from fused medial nasal processes
6-12th week - Secondary Palate - fused palatal shelves from maxillary processes
12th week - Final Palate - fusion of all three processes
Nasal Septum - Nasal cavity forms at the same time frame as the palate (5-12 week).
Development of the Tongue - the tongue develops as growths from the mid-anterior region on the inner surface of the first 4 brachial arches. anterior of tongue ← 1st Branchial arch
posterior of tongue ← 2nd, 3rd, and 4th Branchial arches
4.1 Describe the parts of the tooth germ and its embryonic origin.
Odontogenesis - teeth begin developing at 5th - 6th week in
A tooth arises from epithelial and connective tissue (mesenchyme) -both are derivatives of ectodermal germ layer
3 parts of tooth germ:
1. Enamel Organ - originates from the dental lamina, thickening of epithelium, ectodermal germ layer (WILL FORM ENAMEL)
- Dental Papilla - connective tissue under enamel organ, originates from mesenchyme, ectodermal germ layer, will form DENTIN & PULP
- Dental Sac - fibrous cell layer, originates from mesenchyme, ectodermal germ layer, will form periodontal ligament, lamina dura & CEMENTUM
Stratified squamous oral epithelium > thickens.. > dental lamina > enamel organ > tooth germ
4.2 Describe the stages of tooth germ formation.
Stages of Tooth Germ Formation:
- Initiation (6-7th week) – ectoderm gives rise to the oral epithelium and then to the dental lamina with its dental placodes
- Bud stage (8th week) —growth of the dental placode into a bud shape that penetrates the
growing ectomesenchyme - Cap stage (9th-10th week)—future shape of the tooth becomes evident; cells specialize to form the enamel organ. A part of the mesenchyme deep to the buds condenses into a mass within the concavity of the cap of the enamel organ.
This inner mass of ectomesenchyme is called the DENTAL PAPILLA - PRODUCES FUTURE DENTIN & PULP. basement membrane still exists between the enamel organ and the dental papilla and is the site of the future dentinoenamel junction *(DEJ) - Bell stage (11th -12th week) —differentiation of the enamel organ into a bell shape with 4 cell types and the dental papilla into two cell types >
4 LAYERS IN ENAMEL ORGAN
*Outer Enamel Epithelium (OEE) - Cuboidal cells, protective layer
*Inner Enamel Epithelium (IEE) - a single layer of cuboidal cells, FUTURE AMELOBLASTS, separated from dental papilla by basement membrane
*Stellate Reticulum (SR) - inside OEE, protection/cushion, transport nourishment to IEE, made up of loose network of STAR SHAPED epithelial cells
*Stratum Intermedium - inside SR, between SR & IEE, FLAT cells, directly nourishes IEE
- Apposition (various times - happen back and forth, not necessarily 5th) — dental tissues secreted in successive layers as a matrix
- Maturation (various times - happen back and forth, not necessarily 6th) — dental tissue types fully mineralize to their mature form
Basement Membrane:
between dental papilla and IEE
fixed and determines the final shape of a tooth
further cell differentiation and growth occurs around basement membrane (BM)
IEE → ameloblasts – top of BM
Dental papillae → odontoblast – below BM
future DEJ
Secondary Dental Lamina:
before enamel and dentin formation begins
primary dental lamina breaks from oral epithelium
formation of secondary dental lamina → permanent or succedaneous tooth
4.3 Describe the embryonic development of dental structures.
*Dentin Formation (dentinogenesis):
-1st mineralized layer of tooth
-first formed at incisal/cusp area of tooth and progresses rootward
-formed from ODONTOBLASTS
Enamel Formation (amelogenesis):
-product of the enamel organ
-begins after dentin begins, at the dentin surface of the cusp/incisal edge
-AMELOBLASTS* move upward and outward leaving an organic enamel matrix
IEE cells become AMELOBLAST CELLS
*Primary Enamel Cuticle:
-produced by AMELOBLASTS after enamel formation is complete, smooth coating over enamel
Remaining Original Layers - SR, SI OEE and ameloblasts reduced to few layers of cells known as the reduced enamel epithelium - which produces the secondary enamel cuticle
Secondary Enamel Cuticle
-protects tooth until eruption, non mineralized
*Root Formation:
The process of root development takes place after the crown is completely shaped and the tooth is starting to erupt into the oral cavity. complete 1-4 years after eruption The structure responsible for root development is the cervical loop. The cervical loop is the most cervical part of the enamel organ, a bilayer rim that consists of only IEE and OEE. Hertwig epithelial root sheath (HERS) - this sheath or membrane shapes the root(s) and induces dentin formation in the root area, so that it is continuous with coronal dentin.
*Periodontal Ligament & Cementum:
-the circularly arranged fibers of the dental sac become the Periodontal Ligament (PDL) around the tooth root. The PDL produces the CEMENTUM that covers the root dentin and the lamina dura of the tooth socket
4.4 Explain tooth eruption and shedding.
Tooth Eruption Defined: the process by which developing teeth emerge through bone and soft tissue of the jaws and the overlying oral mucosa to enter the oral cavity, contact teeth of the opposing arch, and function in mastication, is often thought of as the emerging of the crown into the oral cavity
Process of Tooth Eruption:
-the occlusal movement of the tooth is brought about by the lengthening of the root and the development of additional bone beneath the root
-the apical end of the developed root is relatively fixed
-as the developing root lengthens, its growing apical end maintains its position
-the crown moves occlusally
-with the exception of the permanent molars, the enamel organ of each permanent tooth develops from the dental lamina lingual to its primary predecessor
-as the root gets longer, the tooth begins to move occlusally. REMEMBER the crown of the tooth is surrounded by the reduced enamel epithelium (REE)
-as the tooth moves occlusally the REE moves with it
-after the tooth emerges into the mouth the REE becomes known as the junctional epithelium
-the tooth comes into occlusion during root formation
-this occlusal movement does not stop when the root is completed, it continues until the tooth is lost or death occurs; it manifests itself in two ways:
*Passive Eruption - as teeth wear down at the “incisal edges” or “cusp tips” due to mastication, the teeth erupt slightly to compensate for this wear; if this did not occur, the relationship of the jaws would change and the patient’s lips would eventually appear more compressed (this can still happen!)
*Supra-Eruption - this occurs when there is a loss of an opposing tooth; this condition allows the tooth or teeth to erupt farther than normal into the space; this can mean serious problems in replacement of missing teeth with a partial denture or fixed bridge
The Process of Primary Tooth Shedding (Resorption and Exfoliation):
-the shedding of primary teeth takes place because of the gradual resorption (disintegrating or eating away of organic material) of their roots and loss of periodontal ligament attachment
-the developing permanent tooth located lingual to or beneath the root of the primary tooth creates sufficient pressure because of it’s increasing crown size to cause resorption of the primary tooth root and of the bone surrounding this primary tooth root
-as the root resorbs, the tooth loosens
-eventually all the periodontal ligament of the primary tooth is lost and the rootless primary crown literally falls off the jaw
-EXFOLIATE means to fall out.
-regardless of its position, the fact that the permanent tooth crown is present and that its root is developing, causes the permanent tooth crown to move occlusally toward the surface of the oral cavity. This creates pressure on the root of the primary tooth. It is believed that this pressure promotes “osteoclasts” to form and begin resorbing the primary tooth root (also dentinoclast and cementoclast)
-“resorption” of a primary tooth takes place for about one year prior to “exfoliation”
5.1 Identify each tooth in the primary dentition according to location and eruption date, exfoliation pattern, and anatomical features.
RULE: mn > mx
a) 1’s 6-10 months
b) 2’s 7-10 months/9-12 months
c) 4’s 12 -18 months
d) 3’s 16-22 months
e) 5’s 20-32 months/24-32 months
Sequence 1, 2, 4, 3, 5
Exfoliation begins 2-3 years after the deciduous root is fully formed. The root begins to resorb at its apical end and resorption continues until the entire root has disappeared and the tooth falls out
5.2 Compare the anatomical features of deciduous teeth to their permanent counterparts.
Primary/Deciduous Characteristics differing from Permanent Counterparts
-Anterior teeth have smaller crowns and roots
-Have no mamelons
-Molars are wider mesial to distal than permanent bicuspids
-Narrower roots and longer in comparison with the crown length
-Narrow cementoenamel junction
-The cervical ridge of enamel at the cervical third of the crowns of deciduous anterior teeth are very prominent labially and lingually.
-Buccocervical ridges of molars are much more pronounced creating a more bulbous or “bell-shaped” appearance
-Roots are more slender and longer and flare apically to allow room in between for the developing permanent tooth crowns.
-Lighter in colour more white with a bluish cast
-Pulp chambers are large compared to crown size
-Pulp horns extend more occlusally
-Less dense pulp
-Less dense enamel with inconsistent depth
The term “primate spaces” refers to the space mesial to the maxillary cuspids and distal to the mandibular cuspids. There is a mandibular primate space between cuspid & first molar AND a maxillary primate space between lateral incisor and cuspid.
The term “leeway space” refers to arch length space that is gained due to the fact that permanent bicuspids are smaller mesial-distally than the primary molars. This space becomes apparent as the primary molars exfoliate and are replaced by their permanent successors.
5.3 Describe the function of primary dentition.
These teeth are extremely important for the proper development of the muscles of mastication, the formation of the bones of the jaws and the eventual location, alignment, and occlusion of the permanent teeth
- Maintain a place for the permanent teeth
The resorption of the deciduous roots helps to guide their erupting permanent replacements into place. The succedaneous teeth follow the resorbing root through the bone into the proper location
The primary teeth are important in speech development and in the psychological development of the child’s personality (appearance).
5.4 Describe the occlusion of the primary dentition.
-The spacing of the deciduous teeth plays an important role in the occlusion of the permanent teeth. Spacing between deciduous teeth, especially the anterior teeth is needed to provide adequate room for the larger permanent teeth.
The position of the deciduous second molar is an important determinant of permanent tooth alignment.
Mesial Step - Most children have a mesial step between the distal surfaces of the second primary molars. By this we mean, the lower molars are situated more mesial than their maxillary counterparts
Flush Terminal Plane - A smaller but still large group of children exhibit a flush terminal plane, with the distal surfaces of the primary second molars even with each other
Distal step - A small minority has a distal step in which the mandibular molars are situated more distally than their maxillary counterparts
6.1 Identify each anterior tooth in the permanent dentition according to the location, eruption date, function and identifying features - MAX CENTRAL INCISOR
Eruption: 7-8 years
Morphology: 1 root, 1 canal, 4 lobes, 3 mamelons (that may have a labial depression)
Distinct Characteristics:
-Widest tooth mesial to distal
-Mesial side nearly straight
-Distal side more curved
-Curved Cingulum
-Broad lingual fossa
-Attrition occurs such that the incisal edge will slope upward from facial to lingual
6.1 Identify each anterior tooth in the permanent dentition according to the location, eruption date, function and identifying features - MAX LATERAL INCISOR
Eruption: 8-9 years
Morphology: 1 root (similar in length to central incisor), 1 canal, 4 lobes, 3 mamelons (corresponding to labial depressions)
Distinct Characteristics:
-Varies in form more than any other tooth except the third molars
-May be congenitally missing
-The lingual fossa is deeper than central incisors and is more likely to have a lingual pit
-Attrition occurs the same as central incisors, with the slope upward from facial to lingual
6.1 Identify each anterior tooth in the permanent dentition according to the location, eruption date, function and identifying features - MAX CUSPIDS
Eruption: 11-12 years
Morphology: 1 root, 1 canal, 4 lobes
Distinct Characteristics:
-Single cusp
-The longest tooth in the mouth
-The most convex labial surface of all teeth
-Large lingual cingulum
-2 lingual fossa separated by a lingual ridge
-May become impacted due to its eruption pattern
6.1 Identify each anterior tooth in the permanent dentition according to the location, eruption date, function and identifying features - MAND CENTRAL INCISORS
Eruption: 6-7 years
Morphology: 1 root, 1 canal, 4 lobes, 3 mamelons (if labial depressions occur, the are very shallow)
Distinct Characteristics:
-Narrowest mesial-distal of all teeth in the dentition
-The smallest root of all dentition
-No tubercle or pit present
-Attrition occurs so that the incisal edge appears to slope upward from facial to lingual (do to occlusion with the cingulum of max incisors)
-Small lingual foassa & cingulum
6.1 Identify each anterior tooth in the permanent dentition according to the location, eruption date, function and identifying features - MAND LATERAL INCISORS
Eruption: 7-8 years
Morphology: 1 root, 1 canal, 4 lobes, 3 mamelons
Distinct Characteristics:
-Slightly wider and larger than mandibular central
-Similar in appearance to central incisor
-The root is larger in all dimension than that of the central incisor
-Attrition pattern is also included from facial to lingual due to occlusion with maxillary incisor cingulum
6.1 Identify each anterior tooth in the permanent dentition according to the location, eruption date, function and identifying features - MAND CUSPIDS
Eruption: 9-10 years
Morphology: 1 root sometimes apical third is bifurcated, 1 canal, 4 lobes
Distinct Characteristics:
-The longest root of all mandibular teeth
-Smaller than the maxillary cuspid with a much less developed cingulum
-The facial surface is the most convex of all mandibular teeth
6.2 Identify each posterior tooth in the permanent dentition according to the location, eruption date, function and identifying features - MAX 1st BICUSPIDS
Eruption: 10-11 years
Morphology: 2 roots (buccally & lingually), 2 canals, 4 lobes, 2 cusps (B & Li)
Distinct Characteristics:
-Usually 2 roots, bifurcating near the middle third of the root
-Has two canals, even if the root does not bifurcate
-The buccal cusp is longer and wider than the lingual cusp, thus the tooth appears similar to the cuspid from the facial side
6.2 Identify each posterior tooth in the permanent dentition according to the location, eruption date, function and identifying features - MAX 2nd BICUSPID
Eruption: 10-12 years
Morphology: 1 root, 1 canal possibly, 4 lobes, 2 cusps (B & Li)
Distinct Characteristics:
-Buccal and lingual cusps are more equal in length than on the 1st bicuspid
-The tooth is wider B-Li than Mesial-Distal
- The occlusal surface may appear wrinkled with many supplementary grooves
6.2 Identify each posterior tooth in the permanent dentition according to the location, eruption date, function and identifying features - MAND 1ST BICUSPIDS
Eruption: 10-11 years
Morphology: 1 root, 1 canal, 4 lobes
Distinct Characteristics:
-Two cusps buccal and lingual
-Lingual cusp is small and afunctional
-Mesial-distal size is similar to buccal-lingual size, so tooth appears almost round
6.1 Identify each anterior tooth in the permanent dentition according to the location, eruption date, function and identifying features - MAND 2ND BICUSPIDS
Eruption: 12-13 years
Morphology: 1 root, 1 canal, 4 lobes, 2 occlusal variations are found, 2 cusps (bu & ling) 3 cusps (B, ML and Dl)
Distinct Characteristics:
-Has a longer root than the first bicuspid
-More supplemental grooves than first bicuspid
-Groove pattern is “Y” if 3 cusp form and “U” or “H” if 2 cusps form
6.2 Identify each posterior tooth in the permanent dentition according to the location, eruption date, function and identifying features - MAX 1ST MOLAR
Eruption: 6-7 Years
Morphology: 3 roots, 3 canal, 4 + 1 lobes (4 functional cusps plus cusp of Carabelli which is non functional [on ML cusp])
Distinct Characteristics:
-Largest maxillary tooth
-Largest crown of the entire dentition
-Wider buccal-ling than mesial-distal
-The buccal pit at the end of the buccal groove may be present
-Non-Succedaneous
-Oblique ridge running from ML to DB
6.2 Identify each posterior tooth in the permanent dentition according to the location, eruption date, function and identifying features - MAX 2ND MOLAR
Eruption: 12-13 years
Morphology: 3 roots (MB, DB L), 3 canals, 4 lobes
Distinct Characteristics:
-Roots are closer together (less divergent) than those of the first molar
-Oblique ridge is less prominent than that of the first molar
-The buccal groove may also end in a pit
-More supplemental grooves than the first molar
-Overall Smaller than the first molar
-no cusp of Carabelli
-Non-succedaneous
6.2 Identify each posterior tooth in the permanent dentition according to the location, eruption date, function and identifying features - MAX 3RD MOLAR
Eruption: 17-21 years (if at all)
Morphology: 3 roots may be fused, 3 canals, 3 or 4 lobes usually but if there are 3 cusps there are 3 lobes, DL cusp may be absent
Distinct Characteristics:
-Varies anatomically more than any other max molar
- May be impacted or need to be extracted due to cleaning considerations
-May erupt toward the cheek
-Non-succedaneous
6.2 Identify each posterior tooth in the permanent dentition according to the location, eruption date, function and identifying features - MAND 1ST MOLAR
Eruption: 6-7 years
Morphology: 2 roots, 3 canals (MB, M, D), 5 lobes, 5 distinct and functional cusps: MB, DB, D and DL
Distinct Characteristics:
-2 facial (buccal) developmental grooves which may end in pits
-Tooth is wider on the buccal than the lingual, giving tooth a trapezoidal shape
-Roots are long and more divergent than the second molar
-Non-succedaneous
6.2 Identify each posterior tooth in the permanent dentition according to the location, eruption date, function and identifying features - MAND 2nd MOLAR
Eruption: 11-13 years
Morphology: 2 roots, 3 canals, 4 lobes usually, all 4 cusps are nearly identical in size
Distinct Characteristics:
-The occlusal outline is rectangular
-The roots are less divergent than 1st molar
-There are more supplemental grooves than 1st molar
-Non-succedaneous
