Normal Periodontum Pt. 2 Flashcards
composed of a complex vascular and highly cellular connective tissue that surrounds the tooth root and connects it to the inner wall of the alveolar bone. It is continuous with the connective tissue of the gingiva, and it communicates with the marrow spaces through vascular channels in the bone.
Periodontal Ligament
What is the average width of the PDL?
0.2mm
Explain the trend in the periodontal space with use and disuse?
PDL size is diminished around teetht that are not in function or unerupted
PDL siz is increased in that are subject to hyperfuncion
WHat are the most important elements in the PDL?
Principle fibers
collagenous and arranged in bundles and which follow a wavy course when viewed in longitudinal section of the PDL
Principle Fibers
Where do the terminal ends of the PDL principle fivers insert?
What are their names?
They insert into the cementum and bone.
SHARPEY FIBERS
The principal fiber bundles consist of individual fibers that form a continuous ___ ___ between tooth and bone.
Anastamosing Network
The amount of collagen ina tissue can be determined by what?
its hydroxyproline content.
High= lots of collagen
is a protein that is composed of different amino acids, the most important of which are glycine, proline, hydroxylysine, and hydroxyproline
Collage
What is collagen responsible for?
maintenance of the** framework** and the toneof tissue
WHere does collagen synthesis occur?
inside the fibroblasts
Tropocollagen molecues agregate into what that are packed together to form fibrils?
Microfibrils-> fibrils
WHat 4 cells synthesize collagen?
- Fibroblast
- Chondrobkast
- Osteoblasts
- Odontoblast
WHat type of collagen mainly makes up principle fibers?
Type 1
whereas reticular fibers are composed of what kind of collagen
Collagen 3
WHat collagen is found in the basal lamina?
Collage 4 (IV)
What are the 6 fiber groups of the PDL?
- transseptal
- alveolar crest
- horizontal
- oblique
- apical
- Interradicular fibers
Tall and handsome only at Ibiza
What fiber group?
fibers radiate in an irregular pattern from the cementum to the bone
Found only on the apical region of the socket
Apical Group
WHat group of PDL fibers is found only on the apical region of the socket?
Apical group
What fiber group?
Right angles to the long axis of the tooth
Horizonal Group
What fIber group?
The largest group
Extends from the cementum in a coronal direction obliquely to the alveolar bone.
Oblique fibers
extend obliquely from the cementum just beneath the junctional epithelium to the alveolar crest
Alveolar Crest Fibers
What fiber group?
Extend over the alveolar bone crest and are embedded in the cementum of adjacent teeth where they form an interdental ligament
Transseptal Fibers
If there is adjacent tooth loss, which principle fiber will be lost?
Transseptal fibers
WHat fiber group?
Fan out from the cementum to the tooth in the furcation area of multirooted teeth
Interradicular FIbers
WHat are the 4 types of cells in the PDL?
- Fibroblasts
- Cementoblasts
- Osteoblasts
- Epitehlias rest cells + immune system cells
WHat are the most common cells in the PDL?
Fibroblasts
What kind of cells in PDL?
ovoid or elongated cells oriented along the principal fibers, and they exhibit pseudopodia-like processes
Fibroblasts
What are the two main functions of fibroblasts?
- Synthesize collagen
- Phagocytose old collagen fibers and degrade them via enzyme hydrolysis
Collagen turnover is regulated by fibroblasts
What 4 cells are also seen in the cemental and osseous surfaces of the PDL.
- Cementoblasts
- Osteoblasts
- Odontoblasts
- Osteoclasts
What PDL cell?
- Uninucleated cells
- Cuboidal in shape
- Synthesize bone proteins
- Synthesize alkaline phosphatase (used for mineralization of bone)
Osteoblasts
What PDL cell?
- Observed during phases of active cementum deposition
- Oval to cuboidal in shape
- Large nuclei
- After some cementum has been deposited, mineralization begins with the help of calcium and phosphate ions
Cementoblasts
WHat PDL Cell
form a latticework in the periodontal ligament and appear as either isolated clusters of cells or interlacing strands
Epithelial Rests of Malassez
considered remnants of the Hertwig root sheath, which disintegrates during root development.
Epithelial rests of Malassez
epithelial rests proliferate when stimulated and they participate in the formation of what?
periapical cysts and lateral root cysts.
What cells work immune defense in the PDL?
- neutrophiles
- Lymphocytes
- macrophages
- mast cells
- eosinophills
WHat is shown this x-raY?
Lateral root cyst; causes by Epithelial rest cells
The PDL also contains a large proportion of ____ ____ that fills the spaces between fibers and cells.
- Amorphous gel-like substance surrounding the cells
- Transparent, colorless, and fills the spaces between fibers and cells
- Fibers interspersed in
Groud Substanes
clear
The two main components of ground subatance are?
- glycosaminoglycan
- Glycoprotiens
What is the water content in ground substance?
70%
What part of ground substance?
participate in several biologic functions, including cell adhesion, cell–cell and cell–matrix interactions, binding to various growth factors as coreceptors, and cell repair.
Cell surface Proteoglycans
A glycosaminoglycans
WHat are 5 physical functions of the PDL?
- Provides soft tissue casing to protect vessles and nerves.
- Transmission of occlusal force to bone
- Attach teeth to bone
- Maintain gingival tissue inproper relationshipwith teeth
- SHock absorbtion
Cells of the PDL participate in the formation and resorption of cementum and bone, which occur when?
- Physiologic tooth movment
- Orthodontic movment
- accomondation of periodontum to occlusal forces
- repair of injury
The PDL is supplied with ____ which can transmit **tactile, pressure, and pain sensations **via the trigeminal pathways
SENSORY NERVE FIBERS
the ability of periodontal ligament cells to synthesize and secrete a wide range of regulatory molecules is an essential component of tissue remodeling and ___ ____ ____
PDL homeostasis.
the calcified, avascular mesenchymal tissue that forms the outer covering of the anatomic root.
Cementum
What are the 2 main kinds of cementum?
- Acellular= primary
- Cellular= secondary
Both consist of a calcified interfibrillar matrix and collagen fibrils.
What are the two main sources of collagen fibers the cementum?
- **Sharpy Fibers (extrinsic) **embeded in principle fibers of the PDL and formed by fibroblasts
- **Matrix fibers (intrinsic) **fibers of the cementum made by cementoblasts.
What cell?
also form the noncollagenous components of the interfibrillar ground substance, such as proteoglycans, glycoproteins, and phosphoproteins.
+ collagen
Cementoblasts
What is composed of
- 90% type 1 collagen
- 5% type 3 collagen
organic matrix of cementum
Sharpey fibers, which constitute a considerable proportion of the bulk of cementum, are composed of mainly what type of colagen?
Type 1 collagen
WHat is the first kind of cementum formed? Where does it cover? When is if formed? What is predominatley made of? Principle role?
- Acellular cementum
- covers cervical 1/3 of the root.
- Formed before tooth reaches occlusal plane
- Majority made up of sharpey fibers
principle role is supporting the tooth
WHat is the 2nd kind of cementum formed? Where does it cover? When is if formed?
- Cellular cementum
- Covers apical 1/3rd of root
- Formed AFTER tooth reaches occlusal plane
- Contains cementocytes, less sharpey fibers
- Less calcified
Cellular cementum contains cells ____ in individual spaces (lacunae) that communicate with each other through a system of anastomosing canaliculi.
Cementocytes
cellular afibrillar cementum found as?
Coronal cementum
Acellular extrinsic fiber cementum found in?
cervical third of roots
Cellular mixed stratified cementum found in?
the **apical third **of the roots and apices and in Furcation areas
Cellular intrinsic fiber cementum found in?
it fills the resorption lacunae (indv. spaces)
WHat is the main inorganic component of cementum?
Hydroxyapatite. 40-50%
less than that of bone (65%), enamel (97%), or dentin (70%).
What has shown to enhance the proliferation of gingival fibroblasts and PDL cell?
Cementum-derived growth factor
Cause What?
- Local conditions include: Trauma from occlusion, orthodontic movement, pressure from maligned teeth, cysts, tumors, periodontal disease
- Systemic conditions include: resorption, hypothyroidism, Paget’s disease
Cementum Resorbtion
WHere is cementum the thickest?
Thickest in apical 3rd and frucation area (cellular cementum), thick distal, apical thickens with age.
WHat can cause exposure of cementum?
GIngival recession or periodontal diseases
Caries, periodontal disease, dential sensitivyt
The cementum at and immediately subjacent to the?
Cementoenamel Junction CEJ
WHat CEJ relationship?
about 60% to 65% of cases, cementum ____ the enamel
Overlap
WHat CEJ relationship?
in about 30%, an ____ to ____ butt joint exists
Edge to edge
WHat CEJ relationship?
5% to 10%, the cementum and enamel fail to?
Fail to meet
In the case of cementum and enamel not meeting, ___ ___ may result in accentuated sensitivity as a result of exposed dentin
Gingival Recession
a **prominent thickening of the cementum. **It is largely an age-related phenomenon, and it may be localized to one tooth or affect the entire dentition
hypercementosis
spikelike type of hypercementosis generally results from excessive tension caused by
- Orthodontic tx
- Essive tension of occlusal forces
Are all what?
- Trauma from occlusion
- orthodontic movement
- pressure from maligned teeth
- Cysts, tumors
- periodontal disease
Local conditions that result in cementum resorbtion
Are all what?
- calcium deficiency
- hypothyroidism
- hereditary fibrous osteodystroph
- and Paget disease
Systemic conditions that predispose an individual to cementum resorbtion
What 2 things have have been shown to be effective in cementum regeneration
rests of Malassez and growth factors
Fusion of the cementum and the alveolar bone with obliteration of the periodontal ligament
Ankylosis
occurs in teeth with cemental resorbtion, abnormal repair
Portion of the mandible and maxilla that form and support the sockets of the teeth.
Specialized connective tissue
Alveolar Process
forms when the tooth erupts to provide the **osseous attachment to the forming periodontal ligament; **it disappears gradually after the tooth is lost.
Alveolar Process
alveolar processes develop and undergo remodeling with tooth formation and eruption, they are what?
tooth-dependent bony structures.
Bone of the jaw, the portion of the jaw located apically but unrelated to the teeth
basal bone
3 main contants of bone
- 2/3rd organic matter
- 1/3rd inorganic matter
What component of bone?
is composed principally of the minerals calcium and phosphate, along with hydroxyl, carbonate, citrate, and trace amounts of other ions, such as sodium, magnesium, and fluorine
hydroxyapatite crystals 2/3rd bone structure
The inorganic matter
What component of bone?
consists mainly of collagen type I (90%), with small amounts of noncollagenous proteins such as osteocalcin, osteonectin, bone morphogenetic protein, phosphoproteins, and proteoglycans
Bone organic matrix
What 2 protiens ?
cell-adhesion proteinsthat appear to be important for the adhesion of both osteoclasts and osteoblasts
Osteopontin and bone sialoprotein
Bone deposition by ____ is balanced by resorption by ____ during tissue remodeling and renewal.
Lay down= osteoblast
Resorb= Osteoclast
Bone contains 99% of the body’s ____ ions and therefore is the major source for ____ release when the ____ blood levels decrease; this is monitored by the what?
Calcium!
Monitored by parathyroid gland
bone matrix that is laid down by osteoblasts is nonmineralized what?
Osteoid
While** new osteoids is being deposited**, the older osteoids located below the surface becomes ____ as the mineralization front advances.
Become mineralized!
____ originate from hematopoietic tissue
Osteoclasts
Explain 4 stesp of bone resorbtion
- Attachment of osteoclasts to the mineralized surface of bone
- Creation of asealed acidic environment through the action of the proton pump, which demineralizes bone and exposes the organic matrix
- Degradation of the exposed organic matrix to its constituent amino acids via the action of released enzymes (e.g., acid phosphatase, cathepsin)
- **Sequestering **of mineral ions and amino acids within the osteoclast
Cells that produce the organic matrix of bone, are differentiated from pluripotent follicle cells.
Osteoblasts= form
Alveolar bone is formed during fetal growth by ?
consists of a calcified matrix with osteocytes enclosed within spaces called lacunae.
intramembranous ossification
consists of dense, lamellated bone, some of which is arranged in haversian systems and bundle bone.
Socket Wall
the term given to bone adjacent to the PDL that contains a great number of Sharpey fibers.
Localized within the alveolar bone proper.
Bundle Bone
consists of trabeculae that enclose irregularly shaped marrow spaces lined with a layer of thin, flattened endosteal cells
Cancellous portion of alveolar bone
____ bone is found predominantly in the interradicular and interdental spaces and in limited amounts facially or lingually, except in the palate
Cancellous bone
In the adult human, more cancellous bone exsists where?
More in maxilla than mandible
The tissue that covers the outer surface of bone is termed
PERIOSTEUM
tissue that lines the internal bone cavities is called
Endosteum
The Periosteum consists of an **inner layer **composed of ____ surrounded by osteoprogenitor cells, which have the potential to differentiate into osteoblasts, and an outer layer rich in blood vessels and nerves and composed of collagen fibers and fibroblasts
Osteoblasts = inner layer
Vessles, nerves, collagen fibers, fibroblast= outer layer
consists of cancellous bone that is bordered by the socket wall cribriform plates (i.e., lamina dura or alveolar bone proper
Interdental Septum
Isolated areas in which the root is denuded of bone and the root surface is covered only by periosteumand overlying gingiva are termed
Fenestration
When the stripped areas extend through the marginal bone, the defect is called
Dehiscenece
Orthodontic tooth movement is thought to result from site-specific bone remodeling in the abcesne of what?
No inflammation
Tensional forces (making room) stimulates activity of what cells?
Osteoblasts= build bone!
Compresson forces (tightening space) stimulates activity of what cells?
Osteoclasts= break bone
Explain principle fibers of PDL in horizontal force
Tesion areas= fibers are taut
Compression areas= fibers are wavy/ compressed
Blood supply to the supporting structures of the tooth is derived from what to arteries
to the mandible and maxilla?
inferior & superior alveolar arteries
How does blood from the inferior and superior alveolar arteries reach the PDL? 3 soruces
- Apical vessles
- Penetrating vessels for alveolar bone
- Anastmosing vessles from gingiva
what kind of connective tissue?
- Blood
- Lymph
Fluid
what kind of connective tissue?
- Cartilage – hyaline, elastic, fibrous * Bone – compact, spongy
Supporting Connective Tissue
what kind of connective tissue?
- Loose – areolar, adipose, reticular
Lamina Propria of the mucous membrane - Dense– tendon (muscle to bone), ligament (bone to bone; Periodontal Ligament
Connective TIssue Proper
Important in periodontal diagnosis (reference point to measure attachment loss)
CEJ, varies by tooth and location
calcified masses called _____ which are adherent to or detached from the root surfaces
Cementicals
- Nerves and vessels pass into the PDL prior to entering the
Apical Forament
2 Nerves supplying the PDL are?
- Superior Alveolar Nerve
- Inferior Alveolar Nerve
** Immature form of elastin**
* Fibers run parallel to the root surface in a vertical direction * Bend to attach to cementum in the cervical third of the root * Thought to regulate vascular flow
Oxytalan Fibers
What kind of bone?
Embryological and healing phases
Characterized by the irregular arrangement of collagen fibers, large cell number, and reduced mineral content.
Woven bone
What kind of bone?
Compact and Cancellous
Lamellar bone
