Chapter 8- Supporting Structures: The Periodontium

periodontium

structures that surround, support, and are attached to the teeth

what 2 groups can the periodontium be divided into?

1. gingival unit

2. attachement unit

what parts are included in the gingival unit of the periodontium?

-free gingiva

-attached gingiva

-alveolar mucosa

what is gingiva composed of?

very dense mucosa called MASTICATORY MUCOSA and has thick epithelial covering and keratinized cells

what is the underlying mucosa of the gingiva composed of?

dense collagen fibers

where else in the oral cavity is masticatory mucosa found besides the gingiva?

the hard palate (designed to withstand the trauma to which is subjected in grinding food)

lining mucosa

-thin, non-keratinized and freely moveable

-composed of loose connective tissue and muscle fibers

-includes: buccal mucosa, ventral side of tongue etc

what kind of appearance/texture does gingiva have?

stippled surface

what kind of fibers are in lining mucosa?

collagenous and elastic

what kind of fibers are found in masticatory mucosa?

collagenous

free gingiva

-extends from the gingival margin to the base of the gingival sulcus

-forms a collar, which is separated from the tooth by the gingival sulcus

-free gingival margin around a fully erupted tooth is about 0.5-2mm coronal to the CEJ

if a gingival sulus is healthy, what will the depth not exceed?

3mm

gingival papilla (interdental papilla)

part of the free gingiva that is the triangular shaped gingiva between the teeth

if the gingival papilla is unhealthy, what will it look like?

inflammation evident by red color, puffy appearance and blunted apex

for the gingival papilla, the adjacent tooth determines its shape by what 3 things?

1. location of the CONTACT AREA of adjacent tooth

2. shape of interproximal surfaces

3. CEJ of adjacent tooth

gingival sulcus

-space between free gingiva and the tooth

-inner portion lined with non-keratinized epithelium

-outer portion covered with keratinized epithelium

-attached gingiva begins at the base of the gingival sulcus

-the gingival groove is often the base of the sulcus on the outer side of gingiva

attached gingiva

-extends from base of the sulcus to the mucogingival junction

-keratinized, stratified squamous epithelium

-attached to bone and cementum by collagenous fibers

-stippled texture caused by rete peg formation

-light to dark pink in color

rete peg formation

the irregular binding of epithelium to the bone by collagen fibers (causes depressions/dimples where epithelium is pulled tight to the bone)

how is gingiva connected?

-connected to tooth buccally and lingually (proximal sides) by collagenous fibers formed by fibroblasts (connective tissue)

what is the name of the fibers embedded into the cementum?

sharpey's fibers (extend from cementum to papillary area of the gingiva)

some fibers curve towards the mucosa of the free gingiva and interlace with one another and some fibers pass directly across from cementum to gingiva, what is the function of these fibers?

-to keep the gingiva closely attached to tooth surface

-these fibers prevent free gingiva from peeling away from the tooth and keep the ATTACHED GINGIVA FIRMLY ATTACHED

-prevent apical migration of the epithelium attachment/gingival recession

proximally fibers arise from cementum but from a higher level, why?

because of the curvature of the CEJ interproximally

what does the curvature of the CEJ allow for in terms of fibers?

allows for more room for cementum to attach to gingiva

what does the transseptal group of fibers do?

travel across interproximal space and binds to adjacent tooth, BINDING ONE TOOTH TO ANOTHER

what do circular fibers do?

surround the teeth TYING THEM TOGETHER

where does the blood supply of the gingival tissue come from?

comes from supraperiosteal vessels originating from the lingual, buccal, mental, infraorbital and palatine arteries

alveolar mucosa

-apical to the mucogingival junction

-joins the attached gingiva at the mucogingival junction and is continuous with the rest of the tissues of the vestibule

-red, thin, soft, loosely attached to the underlying bone

-composed of lining mucosa and submucosa contains loose connective tissue and fat

-smooth and non-keratinized

the attachment unit

-is comprised of cementum, periodontal ligament and alveolar bone

cementum

-attachment unit

-hard, bonelike tissue covering roots of teeth

-2 types: cellular and acellular

periodontal ligament

-attachment unit

-tissue that surrounds the roots of the teeth that connects them to alveolar bone (acts as a hammock to cushion the impact between tooth and bone on exertion of pressure)

alveolar bone

-attachment unit

-thin covering of compact bone surrounding teeth

-when viewed radiographically, its called LAMINA DURA

-consists of organic matrix and inorganic matter

-has many openings for blood vessels, nerves and lymphatic vessels

cellular cementum

-formed by cementoblasts (embedded in the cementum)

-covers apical 1/3 of root

-collagen fibers (sharpeys fibers) embedded in it

acellular cementum

-formed by cementoblasts (theyre not embedded)

-covers cervical 1/3 of root

-sometimes covers almost all of the root except the apical portion

-collagen fibers (sharpeys fibers) embedded in it

what is the process in which cementum grows by?

apposition (the addition of new layers on top of one another)

alveolar bone proper

the bone that lines the sockets in which the roots of teeth are held

alveolus

-the socket in which the tooth sits in

-contains sharpeys fibers

what are the 2 types of bone we have?

1. thin bone

2. compact bone

bone tissue is continually undergoing change (true or false)

true

what does our organic matrix include?

collagen and intracellular substance

inorganic matter

apatite crystals of calcium, phosphates and carbonates

trabeculae

-interlacing meshwork that makes up the framework of bone

-is directly related to the demands of function, occlusal stress, bone will be thicker

bone apposition and resorption are related to the functional demands placed on the bone (true or false)

true, such as orthodontics

what will the bone be like with normal occlusal stress?

supporting bone will be thicker and more trabeculae

what will the bone be like if there is no occlusal stress?

supporting bone will be thinner

what does constant pressure on our teeth trigger?

resorption, osteoclasts

what does constant tension on our teeth cause?

apposition, osteoblasts

what is an example of a traumatic occlusal forces?

premature contact during occlusion

what happens when there is not a constant force (intermittent force)?

-results in tooth mobility (not tooth movement)

-PDL becomes inflamed and space widens to relieve pressure and swelling

-lamina dura is compressed

-tooth becomes loose in socket

what are some functions of our periodontal ligament?

-insulates tooth and bone, therefore decreases trauma of being pushed together

-absorbs shock

-dissipates occlusal stress both laterally and apically

-fluids in ligament act as a hydraulic pressure system

what are the 5 groups of periodontal ligament fibers?

1. alveolar crest group

2. horizontal group

3. oblique group

4.apical group

5. interradicular group

what is the function of the alveolar crest group (fibers)?

fibers that extend from cervical area of tooth to alveolar crest

horizontal group (fibers)

from tooth horizontally to alveolar bone

oblique group (fibers)

from cementum to bone

what is the function of the apical group (fibers)?

attach tooth to bone apically

interradicular group (fibers)

between roots of multirooted teeth (in furcation areas)

what does mesial drift compensate for?

compensates for interproximal wear and abrasion

what does our active eruption force compensate for?

compensates for occlusal wear and abrasion

what is masticatory occlusal forces?

chewing

what is orthodontic corrective forces?

pressure on teeth to correct occlusion

what would an example of trauma be in the mouth?

premature contact of the teeth