Welcome to Amyrdh.com!

Contributed by:

Mary Cassatt

University of Medicine and Dentistry of New Jersey

Disclaimer: These notes were copied and pasted from files sent to me by Mary.  They have not been reviewed for errors. You are responsible for checking out the information to verify the accuracy. This site, Amy Nieves, Ashley Quinn, Donna Lawson, and Mary Cassatt are not responsible for typographical errors.

 

Periodontium means “ around the tooth”

• Gingival
• Periodontal ligament
• Cementum
• Alveolar and supporting bone

** surrounds and supports the teeth.

 

Attachment apparatus

• Periodontal tissues= attachment and support of the root in the tooth socket
• Periodontal ligament
• Cementum
• Alveolar and supporting bone

 

ORAL MUCOSA= 3 types

 

1. masticatory mucosa= gingival and hard palate
2. lining mucosa= alveolar mucosa, soft palate, lining of the lips, cheeks, and sublingual area
3. specialized mucosa= dorsum of the tongue

 

MASTICATORY MUCOSA

 

• gingival
• protecting covering
• encircles the cervicle portion of the teeth and covers the alveolar process
• ****SUBDIVSIONS
  free gingival, attached gingival and interdental gingival or papilla
• outer surface stratified squamous epithelium
• under that “ lamina dura”  = gingival connective tissue

 

*** FREE GINGIVA

• marginal gingival
• surrounds neck of tooth
• approx. 1.5 mm wide, smooth surface
• adapts to the enamel
• entry into gingival crevice
• scalloped outline
• posterior less scalloped

 

GINGIVAL CREVICE

• space b/t free gingival and the tooth surface
• lined by nonkeratinized stratified squamous epithelium
• aka sulcus in disease “ pocket”

ATTACHED GINGIVA

·        continuous with the free gingival

·        firmly attached to cementum and periosteum

·        wider on incisal region

·        narrowest first premolar region

 

INTERDENTAL GINGIVA

 

·        extension of free gingival ( margin and lateral borders)

 

LINING MUCOSA

ALVEOLAR MUCOSA

·        not actually part of the periodontium

·        thinner and redder in color

·        movable, smooth

·         

frenum attachments

• folds of alveolar mucosa
• usually seven frena

 

SPECIALIZED MUCOSA

• dorsum of the tongue
• filiform- slender, most abundant, coving entire dorsal top of the tongue, no taste buds
• fungiform- edges of the tongue, broad and flat
• circumvallate= v-shaped grove back of the tongue

 

GINGIVAL EPETHELIUM

 

• stratified squamous
• underlying core of connective tissue
• lamina propria
• oral epithelium
• sulcular epethium
• junctional epithelium
• avascular
• relies on lamina propria for blood supply and nutrients
• stratum basale or stratum germinativum( basal cell layer) deepest layer next to lamina propria
• stratum spinosum- prickle or spinous cell layer
• stratum granulosum( granular layer)
• stratum corneum( keratinized/cornified cell layer) superficial layer, barrier membrane

 

 

CELL RENEWAL

·        producing a pool of cells

·        migrate from basal layer

·        to oral environment

·        ** Keratinization

·        entire thickness is replaced

·        *turn over time

 

 

Oral epithelium

• parakeritinzed stratified squamous epithelium
• gingival=10 days
• skin= 28 days
• contains

1. keratinocytes=  majority, synthesize keratin, mechanical toughness, color pink
2. nonkeratinocytes “clear cells”
3. melanocytes= located in basal layer, brownish pigment,
4. langerhans cells= stratum spinosumm, early defense mechanism
5. merkel cells= basal cell layer. Touch sensory cells

 

SULCULAR EPITHELIUM

• less keratinized, can be parakeratinized
• thin

 

JUNCTIONAL EPITHELIUM

• not visable from the outside
• contact for gingival and the tooth   
• nonkeratinized stratified squamous epithelium
• active basal layer and an inactive suprabasal
• or basal cell and spinous cell layer
• direct attachment to the tooth
• semipermeable membrane= allows movement of fluids and cells  of certain sizes
• cellular turn over
• 4-7 days

 

ALVEOLAR MUCOSA

·        compressible and movablegranular layer not present

·        darker red

·        highly vascular

 

Gingival CONNECTIVE TISSUE

• Lamina Propria
• Connective tissue/epithelium interference
• Not smooth
• Connective tissue ridges
• Absent in health

 

Gingival CoNNECTIVE TISSUE

• Collegen fibers**
• 60 % total volume
• protein composed of amino acids
• Type I gives it firmness

 

GINGIVAL FIBERS

• Sharpey’s fibers= embedded into cementum
• Supracrestal fiber apparatus= located coronal to the crest of alveolar bone
• Circular= encircles the tooth within the free gingival, support and contour, Dentogingival , dentoperiosteal, alveolargingival and transseptal fibers.

 

COLLAGEN ORGANIZATION

 

• Densly or loosly organized

 

CELLULAR AND VASCULAR ELEMENTS

CELLULAR PART

• Fibroblasts
• Macrophages
• Mast cells
• Plasma cells, lymphocytes, and neutrophils

 

CELL TO CELL TISSUE JUNCTION

Epithelium cell to cell attachment

• Held together by desmosomes
• 2 adjacent attachment plaques
• intercellular spaces are wider

 

EPITHELIUM TOOTH SURFACE CONNECTIVE TISUE

• hemidesmosomes
• epithelial attachment= basal lamina and hemidesmosomes
• basal lamina separates the epithelium from the connective tissue

 

DENTOGINGIVAL UNIT

• gingival fibers

 

FORMATION OF DENTOGINGIVAL UNIT

• after completion of enamel , ameloblast produce primary cuticle as their last function,
• before the degenerate and become part of the REP. – connected to the enamel by primary cuticle
• REE fuses with the  oral epithelium at the base of the sulcus forming junctional epithelium
• REE forms lining of the sulcus
• Junctional epithelium produces secondary cuticle

 

ATTACHMENT APPARATUS

Consists of:

Periodontal ligament, cementum, alveolar and supporting bone

Functions as:

Supports and anchor the teeth in the alveolar process

 

PERIODONTAL LIGAMENT

• Composed of collegen fibers and islands of loose connective tissue called interstitial spaces where blood vessels nerves lymphatics and cells are embedded in a ground substance
• Primary cell
• Fibroblast=synthesize collegen, collagenase, and ground substace
• Cementoblasts= formation of cementum
• Osteoblast= bone formation

 

CONNECTIVE TISSUE ATTACHMENT

• Primary component of periodontal ligament is collagen fibers
• Principle fibers
• 2^nd type of connective tissue
• gingival fibers
• principle fibers formd before tooth eruption alveolar crest fibers
• few  elastic fibers
• collagen turnover time is 5 times faster then periodontal ligament than that in bone or gingival b/c of the greater functional demands placed upon it.

 

PERIODONTAL LIGAMENT SPACE

• the more load put on the tooth the periodontal ligament space will be thicker

 

FUNCTIONS OF THE PERIODONTAL LIGAMENT

• acts like a suspensory mechanism attaching the tooth to the alveolar bone
• acts as a shock absorber transmitting occlusal forces to the bone
• serves as a remodeling function by providing cells that are involved in the formation and resorption of the cementum and the bone itself.
• Carries a blood supply to the rest of the periodontium for nutrition
• Transmits tactile pressure and pain perception via the trigminal nerve,
• Allows the feeling of localization to be transmitted through proprioceptive nerve endings

 

ABNORMALITIES

• Epithelial rests of malassez
• Cementicles are calcified bodies of cementum  seen in PDL,

 

CEMENTUM

• Avascular

 

65% cementum overlaps enamel

 

Acellular = before tooth eruption

• Coronal 2/3 of the root
• CEJ= thinnest
• Not involed in laying down cementum

 

Cellular

• Covers the apical third or root and furcations
• Can be laid down on top of acellular

 

PHYSIOLOGIC FEATURES

• Cementum thickens with increasing age
• But the production of cementum slows
• New layer laid down

 

ABNORMALITIES

• Hypercementosis is a condition characterized by an atypical thicking of cementum
• Apical or entire root
• Forces or orthodontic movement

 

ALVEOLAR PROCESS

• Periosteum is c/t that covers the outer surface of the alveolar process
• Well supplied with blood vesels, nerves,
• Endosteum covers the inner surface of the alveolar process facing the tooth surfaces

Parts OF the ALVEOLAR PROCESS

• Alveolar bone proper- CRIBRIFORM plate , hard compact bone, lines tooth sockets, radiographically, lamina dura
• Where sharpeys fibers terminate is bundle bone found at the inner surface
• SUPPORTING BONE
• Compact bone: covers alveolar process, buccal and lingual cortical plates, thicker in the mandible,
•  and cancellous bone, fills the area between the buccal and lingual cortical plate and between the alveolar bone proper

 

MORPHOLOGY

• cortical palte of bone covering the roots of the teeth called radicular bone

 

MICROSCOPIC ANATOMY OF BONE

 

• c/t
• compact bone = haversian system or osteon
• each has central haversian canal
• surrounded by concentrically arranged lacunae, containing osteocyte which communicate with other osteocytes by small canals
• called canaliculi
• haversian canal consists of at least one capillary, which supplies oxygen and nutrients and removes carbon dioxide and waste from the osteocyte
• blood vessels enter by volkmanns canals
• cancellous bone different
• consists of trabeculae or small supporting plates of bone
• which branch and connect to form a meshwork
• ANKYLOSIS = fusion of the bone directly to the root surfaces without an intervening periodontal ligament

 

COMPOSITION OF BONE

·        Alveolar process = collagen fibers & cells embedded in a ground substance ( proteoglycans) = organic component

·        Inorganic salts = calcium and phosphate

·        Salts allow to withstand compression

·        Cells of the alveolar and supporting bone are

1.      osteoblasts, synthesize and secrete bone

2.      osteocytes which are osteoblasts that are embedded within lacunae as bone being laid down

3.      osteoclasts, which destroy or resorb bone

METABOLISM

·        bone is vascular tissue and the least stable od all periodontal tissues

·        constant remodeling

·        more in cancellous bone

·        normal remodeling is occurs by resorption by osteoclasts foloowed by deposition by osteoblats

·        resorbed on pressure side and laid down on tension side

VARIATIONS IN ANATOMY

• more frequently on facial bone then lingual bone
• buttressing occurs at the margin of bone where it thickens in response to increase functional demands.

 

 

PHYSIOLOGY OF TH PERIODONTIUM

• blood that innervates the gingival= supplied by periosteum, PDL and alveolar bone
• supreperiosteal vessels run along the facial and lingual surfaces of the alveolar bone
• gingival plexus= under the oral epithelium
• inferior and superior alveolar arteries = supply the PDL and originate from the apical foramen the alveolar bone , and the gingival
• cortical bone = blood supply , branches from the supraperiosteal blood vessels
• lymphatic drainage = starts from in the papillae of c/t and drains into regional lymph nodes, submandibular
• nerve supply = trigeminal ( 5 th) cranial nerves
• anterior superior alveolar nerve innervate the gingival overlying the maxillary incisors and canines
• middle superior alveolar nerve supply the gingival around the max. premolars
• posterior superior alveolar nerve supply the gingival around the max. molars
• inferior alveolar nerve supply the facial  of man. Incisors canines, premolars and molars
• mental nerve buccal supply facial gingival of the man. Molars
• lingual nerve supplies the man. Lingual gingival

 

self quiz   page 32

 

*** Cementum, alveolar and supporting bone, periodontal ligament = attachment

apparatus

 

****attached gingival is greatest at = max. lateral incisors

 

****primary component of c/t = collagen

 

**** directly attaches the junctional epithelium to the enamel = basal lamina

 

**** attachment of the GINGIVA to the tooth surface = DENTOGINGIVAL UNIT

 

****comprises the biological width  = junctional epithelium, gingival connective tissue attachment

 

*** which bone lines the tooth socket = ALVEOLAR

 

****Semipermeable membrane = junctional epithelium

 

vascular structure = lamina propria

 

**** this structure does not contain arteries that supply blood and lymphatics to the free gingival = cementum