Periodontium Flashcards by Brittany Woodard

Name the scientist:

Used simple microscopes
Discovered “animalcules”
Observed details of enamel, dentin (tubules),and bone
Did NOT find cementum

Anton van Leeuwenhoek

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Name the scientist:

Observed malpighian corpuscles and pyramids of kidneys
Noticed something on the roots: Substantia Tartarea

Marcello Malpighi

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Name the scientist:

Observed Purkinje cells and fibers

Jan Purkinje

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Name the scientist:

Observed Striae of Retzius
Investigated dentin tubules

Anders Retzius

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What is Greene Vardiman Black known for?

The functional understanding of cementum
Classification of caries
Amalgam preparations
Foot powered drill

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Who recognized….

Sharpey’s fibers in cementum and bone unite the periodontal complex

and described….

Reparative cementum for the first time

GV Black

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TERM – consits of the root dentin, associated root canals, and pulp

Tooth Root

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TERM – the support system for the tooth; contains:

Cementum
Alveolar Bone
Periodontal Ligament
Gingiva and associated ligaments

Periodontium

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TERM – defines edge of enamel organ during bell stage

Cervical Loop

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TERM –

defines the forming root
extension of enamel organ
bilayered structure of OEE and IEE

Herwig’s Epithelial Root Sheath

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How does one tooth get multiple roots?

SIZE

SHAPE

NUMBER OF ROOTS

depends on…

HERS-

Cell Migration

& Cell Proliferation

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HERS induce dental papilla cells to differentiate from ___________ to ___-_______

Ectomesenchymal Cells –> Pre-odontoblasts

(later becomes odontoblasts)

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What stimulates the differentiation of the roots?

Epithelial - Mesenchymal signaling

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What type of genetic disorder occurs in individuals with shortened roots, obliterated pulp chambers, and tooth mobility?

Dentin Dysplasia Type I

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True or False?

Dentin Dysplasia Type I is Autosomal Recessive

False!

Autosomal Dominant

TF’s and SMOC2 are associated!!!

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TERM – type of root developmental defect that results in a large pulp chamber at the expense of a root furcation

Taurodontism

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TERM – type of root development defect that results in deformity in shape and/or direction

Dilaceration

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True or False?

Developmental Root Defects can make teeth more prone to

Breakage
Exfoliation
Ankylosis
Difficulty extration
Orthodontic movement

TRUE

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______ disintegrats shortly after inducing root odontoblast differentiation… some remanents become epithelial rests of Malassez

HERS

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True or False?

Epithelial rests of Malassez can cause cysts

True

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Epithelial Rests of Malassez are surrounded by a _______ _______

Basement Membrane

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True or False?

Root dentin is continuous with crown dentin

True

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Instead of dentinogenesis of crown dentin IEE interacting with the enamel organ

Dentinogenesis of root dentin IEE interacts with _______?

HERS

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List the rising order of how odontoblasts were differentiated from ectomesenchyme (4 names/steps)

Ectomesenchymal Cells
Dental Papilla
Pre-Odontoblasts
Odontoblasts

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What are the two main types of Cementum?

1. Acellular Cementum 2. Cellular Cementum

How would you differentiate between the two types of cementum?

1. If cells are in the matrix 2. Origin of the collagen fibers in the matirx

Acellular cementum will have _____ fiber cementum and is known as _______ cementum

Extrinstic Fiber Primary Cementum

Cellular Cementum will have _____ fiber cementum and is known as ________ cementum

Intrinsic Secondary

Does acellular or cellular cementum form first?

Acellular (Primary)

Primary Acellular cementum covers \_/\_\_ of the root

2/3 coronal part of root

Secondary Cellular Cementum covers \_/\_\_ of the root

1/3 apical portion of root

Cementocytes will be present in - which type of cementum - location on the root?

Secondary (Cellular) Apical 1/3

Name 4 functions of Cementum

1. Attachment 2. Protecting 3. Adjusting 4. Sealing

True or False? Acellular cementum is primarily involved in attachment to the PDL

True

True or False? Acellular cementum is responsible for adjusting tooth position

False - cellular cementum

Rank the 3 mineralized tooth tissues in order of hardness

1. Enamel 2. Dentin 3. Cementum

How is cementum SIMILAR to bone?

1. 50% inorganic (HA) 2. 35% organic -- type I collagen (90%) + III +VII, non-collagenous ptns., and glycosaminoglycans (10%) 3. 15% water

How is cementum DIFFERENT than bone?

1. Avascular 2. Non-innervated 3. No-turnover (Growth by apposition)

Name the mineral (inorganic) % of each mineralized tooth tissue

1. Enamel -- \>95% 2. Dentin -- 70% 3. Cementum -- 50%

Name the 3 types of CEJ relationships

1. Overlap -- C\>E 2. Meet -- C=E 3. Gap -- C-----E

What CEJ relationship can cause problems such as increased risk for caries?

Gap -- dentin is exposed!

Rank the 3 types of CEJ relationships in order of least common to most common

1. Gap - least 2. Meet 3. Overlap - most common

Where are cementoblasts derived from?

Dental Follicle -- \> Ectomesenchyme

Name the cell that is responsible for making acellular and cellular cementum

CementoBLASTS

Cementoblasts remain in the _____ close to the cementum surfact

PDL

Cementoblasts _______ slow cementum growth throughout life and direct cementum \_\_\_\_\_\_

Regulate Repair

TERM -- a subset of cementoblasts that becomes embedded in cellular cementum matrix

Cementocytes

True or False The function of cementocytes is unknown

TRUE

What group of cells produce more products: Cementoblasts or Cementocytes?

Cementoblasts

Cementocytes - Reside in _________ in the maxtix - Have cell processes called ______ to communicate

- Lacunae - Dendrites

True or False? Cementocytes remain in the lacunae only for a small time frame

False-- remain for life!

Name 3 cell types that the **dental follicle** gives rise to (ectomesenchymal origin)

1. Cementoblasts 2. PDL Fibroblasts 3. Osteoblasts

What 2 actions must occur **before** cementum can form?

1. Root Dentin formation -- foundation 2. HERS disintegration -- exposes root dentin surface

\_\_\_\_ _____ \_\_\_\_\_ are secreted by cementoblasts and intermingle with _______ dentin at the CDJ

Intrinsic Collagen Fibers unmineralized

True or False? Initial Collagen Fibers are short extrinsic fibers that are not yet connected with the PDL

False -- **intrinsic**

Once the initial collagen fiber bundles intermingle with the dentin collagen fibers, dentin completes \_\_\_\_\_\_\_\_

mineralization

True or False? The dental follicle was identified prior to the PDL via microscopy

True

TERM -- cells that are responsible for producing primary collagen fiber bundles of PDL space

PDL Fibroblasts

A continuity of ______ fibers will extend from the initial _______ fibers

Extrinsic Intrinsic

What become the mineralized **Sharpey's FIbers** within the cementum?

Extrinsic fibers (extensions) + Initial Intrinsic fibers

True or False? Intrinsic Fibers are the major fiber group for acellular cementum?

False -- EXTRINSIC

Extrinsic fibers enter acellular cementum at high or low density?

HIGH

Extrinsic Fibers are critical to the _______ of acellular cementum

Function

TERM -- mineralized collagen fiber bundles providing strong anchorage of tooth--PDL--Bone

Sharpey's FIbers

What type of cells promote **hydroxyapatite deposition** between and within the collagen fibers curing cementogenesis?

Cementoblasts

Where can Sharpey's fibers be found?

1. Cementum 2. They are continuous with the PDL 3. Alveolar Bone

Acellular Cementum Mineralization Mechanisms: 1. Collagen Substrate -- **fiber fringe** at \_\_\_-\_\_\_\_ interface 2. Cells secrete \_\_\_-\_\_\_\_\_\_ extracellular matrix proteins that participate in mineral precipitation 3. Cells direct ______ inbetween collaten fibers 4. Progressive mineralization of _______ collagen fibers

1. Cementum-PDL 2. Non-collagenous 3. Mineralization 4. Extrinsic

Give brief steps of acellular cementum mineralization

1. Fiber Fringe is present = ready for mineralization 2. FF becomes engulfed and mineralized 3. Now = Sharpey's Fibers 4. Mineralization slowly continues over time

What is the rate at which cementum mineralizes?

~3 micrometers/year

True or False? Acellular cementum will become thicker over time

True

What cells are responsible for the mineralization of the cementoid matrix?

Secondary Cementoblasts

True or False? Cellular cementum mineralization occurs at a much faster rate than acellular does

True

Secondary Cementoblasts produce many ______ collagen fibers and deposit the cellular cementum ECM

Intrinsic

Cellular cementum is often minimal or absent in which of the following teeth?

1. Incisors 2. Canines

TERM -- maintains tooth in proper occlusal position by compensating for enamel attrition throughout life

Adaptive Cementum

True or False? Cellular Cementum can repair cementum resorption anywhere on the root

True

What is the appearance of a cementoid?

a clear unmineralized area "blob"

True or False? Excess cementoid = hypermineralization of cementum

FALSE Results in delayed mineralization

As predentin is to dentin... \_\_\_\_\_\_\_\_ is to cementum

Cementoid

As octeocytes are to bone... \_\_\_\_\_\_\_\_\_\_ are to cementum

Cementocytes

TERM -- embedded in cellular cementum matric and are connected to one another and surface PDL

Cementocytes

True or false? Both acellular and cellular cementum continue growing slowly throughout life

TRUE

What indicate successive layers in cementum?

Longitudinal lines/ Striations/ Appositional growth lines

Would you classify the cementogenesis as a remodeling growth or appositional growth?

Appositional Growth

What is the difference between appositional and remodeling growth?

Appositional -- layering method Remodeling -- "exfoliate & renew" method

True or False? Resorption of cementum can occur

True

What is the **alternative** hypothesis for cementum origin?

1. Dental Epithelium 2. HERS 3. Epithelial-mesenchymal transformation 3. Cementoblast

What is the **classical** hypothesis for cementum origin? **know this one!!**

1. Ectomesenchyme 2. Denal Follicle 3. Cementoblast

Which of the following is NOT a derivative of ectomesenchyme? 1. Alveolar Bone 2. Pulp 3. Enamel 4. Cementum

Enamel!! It is an **ectoderm derivative**

Pick out the common origin of the following oral tissues 1. Odontoblasts (dentin) 2. Fibroblasts (pulp) 3. Cementoblasts 4. Fibroblasts (PDL) 5. Osteoblasts (alv. bone)

Ectomesenchyme

Is this line of events the **alternative or classical** hypothesis if cementum? 1. Cementum 2. Cementoblasts 3. Dental Follicle 4. Ectomesenchyme

Classical Hypothesis

True or False? Ameloblasts are derived from Ectoderm

True

True or False? The primary junctional epithelium and periodontal ligament have the same origin

FALSE PJE -- ectoderm PDL -- ectomesenchyme

What is derived from the reduced enamel epithelium?

Primary Junctional Epithelium

What is derived from HERS?

Root formation

Name the 3 components of the tooth germ

1. Enamel Organ 2. Dental Papilla 3. Dental Follicle

Of the 3 components of the tooth germ, which is derived from ectoderm?

Enamel Organ

Of the 3 components of the tooth germ, which is derived from ectomesenchyme?

1. Dental Follicle 2. Dental Papilla

Name the type of cells that give rise to the PDL

Fibroblasts

Crown Formation is the combination of ______ & ______ from the tooth germ. Are they from the same origin?

Enamel organ & Dental Papilla No Enamel Organ -- Ectoderm Denal Papilla -- Ectomesenchyme

Cells of 4 layers give rise to the reduced enamel epithelium?

1. OEE 2. Stellate Reticulum 3. Stratum Intermedium 4. IEE

What layer of the enamel organ are ameloblasts derived from?

IEE

If there is too little of cementum, name the two consequenses: 1. 2.

1. Cementum Aplasia 2. Hypoplasia

If there is too much of cementum, name the possible consequences:

1. Hypercementosis 2. Possibility leading to Ankylosis

What is ankylosis??

The ankylosis of a tooth is defined as an anatomical fusion of alveolar bone with cementum and can occur any time during eruption, either before or after the tooth erupts into the oral cavity.

Consequences of lost cementum? 1. 2.

1. External Root Resorption 2. Periodontal Disease

Hypophosphatasia (HPP) 1. Rare\_\_\_\_\_ disease 2. Results in mutations in the ______ gene (encodes proteins: TNAP & TNSALP) 3. These proteins break down __________ which is an __________ of mineralization 4. Because of the mutations, there will be a _____ amount of PPi and 5. In order for mineralization, PPi concentration must be maintained or reduced?

1. Rare **skeletal** disease 2. Results in mutations in the ***ALPL*** gene (encodes proteins: TNAP & TNSALP) 3. These proteins break down **pyrophosphate** which is an **inhibitor** of mineralization 4. Because of the mutations, there will be a **High** amount of PPi 5. In order for mineralization, PPi concentration must be maintained or **reduced**?

What will happen if a mutation occurs in the ALPL gene? ALPL --\> TNAP encoded --\> PPi breakdown 1. High or Low Mineralization? 2. High or Low amount of PPi?

1. Low 2. High

If there is a HIGH amount of Mineralization, the amount of PPi must be \_\_\_\_\_

LOW

Hypophosphatasia will have _____ mineralization because of the ______ amount of PPi that inhibits mineralization

Low High

True or False? Hypophosphatasia can affect bone, dentin, and enamel

TRUE

Is acellular or cellular cementum most dramatically affected by hypophosphatasia?

Acellular

Name a few consequences if there is defective or absent cementum 1. 2. 3.

1. Tooth mobility 2. Premature loss of primary teeth 3. Loss of permanent teeth

TERM -- excessive cementum growth

Hypercementosis

PPi levels: Hypocementosis? Hypercementosis?

1. High 2. Low

True or False? Hypercementosis can becaused by genetic disease, trauma, or can be idiopathic?

TRUE Hypocementosis - genetic mutation ALPL gene

Would hypercementosis make an extraction easier or more difficult?

MORE difficult because of ankylosis!!!

True or False? Hypercementosis is generally symptomatic

FALSE - asymptomatic

TERM -- - this protein was discovered in bone (1st), dentin, & cementum - Promotes HA mineral formation - Critical role in acellular cementum - research with knock-out mice

BSP -- Bone Sialoprotein

A BSP knock out mouse will have... Hypoplasia or Hyperplasia? PDL attachment? Bone breakdown?

Cementum Hypoplasia Detached PDL Periodontal breakdown

Name a few reasons root resorption/and or cervical burnout can occur 1. 2. 3. 4.

1. Excessive ortho tx 2. Trauma 3. Severe Periodontitis 4. Genetic Factors \*\* may be idiopathic

What is the most effective treatment for root resorption?

There is no effective treatment! Splint

TERM -- repair mechanism following cementum resorption by odontoclasts/osteoclasts

Repairative Cementum

True or False? Reparative cementum is often cellular reguardless of the location

TRUE

The cortical plates of the mandible are located?

Buccal and Lingual sides of mandible

True or False? The mandible consists of trabecular/spongy bone

True - inferior to teeth, body of mandible

TERM -- bone lining the socket/inner aspect facing the tooth

Bundle Bone/ Alveolar Bone Proper

Alveolar Bone includes ______ collagen fiber bundles which are mineralized Sharpey's Fibers

extrinsic

Primary fibers entering the bundle bone are (larger/smaller) in diameter and (less/more) dense versus cementum?

Larger Less

TERM -- a radiopaque layer lining the socket of a tooth in the alveolar bone in a radiograph. Commonly seen after EXT.

Lamina Dura

True or False? Lamina Dura opacity is because of an increase in the amount of mineral content

FALSE It is from thick bone without trabeculation

On a radiograph, PDL appears : Lamina Dura :

PDL appears : Radiolucent Lamina Dura : Radiopaque

True or False? Just because the alveolar bone is compact, does not mean it is entirely solid

TRUE - numerous perforations!

TERM -- a structural component in the alveolar socket that is pierced by many small hole which allow for blood vessels and nerves to enter the PDL space

Cribiform Plate

Which of the following is derived from a monocyte/macrophage? 1. Cementoblast 2. Cementoclast 3. Osteoblast 4. Osteoclast

Osteoclast

Bone remodeling occurs in response to \_\_\_\_\_\_? What 2 cell types work in tandem?

Function Osteoclast and Osteoblasts

Pick out the abnormal function of osteoclasts 1. Remodeling alveolar bone 2. Bone resorption for tooth eruption 3. Resorption of permanent teeth roots 4. Resorption of deciduous teeth when exfoliated/erupting

3. Resorption of permanent teeth roots

The "Mechanostat" theory of the alveolar bone loading indicates: 1. Bone loading causes? 2. Bone unloading causes?

1. Growth 2. Loss

True or False An edentulous mandible will gradually lose alveolar bone

True

TERM -- soft fibrous connective tissue between tooth and alveolar bone

PDL

What makes the periodontal ligament different than a typical ligament?

**THE CONNECTIONS!!** PDL = tooth to bone normal ligament = bone to bone

What is a Gomphosis???

A unique joint tht connects bone to tooth (tooth socket)

True or False? The PDL varies by person-to-person, but is the same width for every tooth Also what is the normal width?

FALSE!! It does vary from person to person AND it varies between different teeth! Normal width = 0.1 - 0.4mm

Provide 6 Fuctions of the PDL

1. Supportive 2. Nutritive 3. Sensory 4. Defensive 5. Maintenance/Reparative 6. Adaptive

True or False After orthodontic tooth movement, the PDL returns to the same width as before ortho

True

Composition of the PDL 1. 2. 3.

1. Ground Substance 2. Collagen Fibers 3. Oxytalan Fibers

What makes up the **Ground Substance** in the PDL?

proteins, proteoglycans, and water

What types of collagen fibers are present in the PDL?

Type I, Type III, Type XII "spliced rope"? 97% of PDL fibers are **collagen** fibers

TERM -- - small elastic fibers - support collagen fibers and blood vessel walls - 3% of fibers - NO elastic fiber bundles

Oxytalan Fibers

True or False? As a tooth is erupting, PDL collagen fibers change from a **disorganized** to **organized** arrangement as the root lengthens, cementum forms, alveolar bone forms...etc.

True

Name the 6 PDL Principal Fiber Groups \*\* **TAHOAI \*\***

1. Transseptal Ligament 2. Alveolar Crest Group 3. Horizontal Group 4. Oblique Group 5. Apical Group 6. Interradicular Group \*\* **TAHOAI \*\***

What is the most predominant group of the 6 PDL principal fiber groups?

Oblique -- main group resisting occlusal loads (intrusive force)

True or False? The PDL is very cellular

TRUE

Name some of the cells that are within the PDL

1. Fibroblasts \*\*majority 2. Cementoblasts 3. Osteoblasts & Osteoclasts 4. Epithelial Rests of Malassez 5. Stem Cells 6. Immune Cells

True or False The PDL is very avascular

False!! It is well vascularized! There are superior and inferior alveolar arteries

There are 3 types of routes that blood vessels use to suppy nutrients. What are they? Which is the most common?

Perforating, Apical, and Gingival Most common: Perforating

True or False? Venous drainage flows in the axial direction

True!

TERM -- periodontal complex provides sensory feedback on tooth position, bite force, and presence of objects between teeth

Proprioception

TERM -- Masication can cause damage to teeth and supporting tissues unless controlled by __________ \_\_\_\_\_\_\_\_

Peripheral Feedback

TERM -- Large forces across short distances via hard teeth

Mastication

Name the 4 types of nerve endings identified in the PDL 1. 2. 3. 4.

1. Free endings 2. Ruffini Endings 3. Coiled Endings 4. Ecapsulated Endings

TERM -- type of sensory receptor for painful stimuli

Nociceptor

TERM -- type of receptor that responds to mechanical stimuli

Mechanoreceptor

**Free Nerve Endings** are found along the length of the root and consist of ______ & ______ receptors

1. Nociceptors 2. Mechanoreceptors

**Ruffini Nerve Endings** are found near the apex of a tooth and consist of ___________ receptors

Mechanorecptors

TERM -- ectopic cementum in PDL attached or unattached

Cementicle

Name the 3 types of epithelilium associated with the periodontium

1. Oral Epithelium 2. Sulcus Epithelium 3. Junctional Epithelium

The Junctional Epithelium serves as a barrier to _____ invasion

Microbial

TERM -- Collagen fiber bundles spanning from tooth/bone to gingiva/connective tissue (lamina propria) Function: resisting gingival displacement

Gingival Ligament Groups

Gingival Ligament Groups (4) ## Footnote **\*\* CDDA \*\***

1. Circular Group 2. Dentogingival Group 3. Dentoperiosteal Group 4. Alveologinigval Group **\*\* CDDA \*\***

*Porphromonas gingivalis* is the type of bacteria that causes ____________ \_\_\_\_\_\_\_

Periodontal Disease - Periodontitis

Name 3 things that are lost when a patient has Periodontal Disease 1. 2. 3.

1. Cementum 2. PDL 3. Alveolar Bone

Name a few ways periodontal regeneration can occur/prevention

1. Scaling 2. Root Planing 3. Antibiotic Therapy 4. Guided Tissue Regeneration (Grafting) 5. Emdogain 6. Growth factors \*\*\* ALL depend on presence of stem/progenitor cells