The periodontium Flashcards
what is the periodontium?
the structures that support or hold the teeth in their proper position in the alveolar process
- divided into 2 units
what are the 2 units of the periodontium?
1 - gingival unit
2 - attachment unit or apparatus
what are the 3 parts of the gingival unit?
consists of
1 - free gingiva/unattached gingiva
2 - attached gingiva
3 - alveolar mucosa
what are the 3 parts of the attachment apparatus for teeth in their sockets?
1 - alveolar bone
2 - PDL
3 - cementum
what is the free gingiva?
extends from the gingival margin to the base of the sulcus. light pink. 0.5-2.5 mm in depth
what common tissue makes up free and attached gingiva? what else is attached gingiva made up of?
both are composed of masticatory mucosa. attached gingiva has a thick epithelial and keratinized, underlying mucosa is composed of dense collagenous fibers that help the tissue withstand trauma. fibers are attached to bone and cementum
where is the attached gingiva?
extends from the base of the sulcus to the mucogingival junction
what is alveolar mucosa?
lining mucosa
- described as: thin and freely moveable; tears or injures easily; epithelium covering this lining mucosa is thin and nonkeratinized; composed of loose connective tissue and muscle fibers
where is alveolar mucosa?
continuous from the mucogingival junction to the lining of the cheeks and lips and floor of the mouth (lining mucosa)
what is the sulcus?
the space between the free gingiva and the tooth, 0.5 mm - 3 mm in depth
what is gingival papilla/interdental papilla?
the free gingiva located in the triangular shaped interdental spaces between the teeth
- the tissue’s apex is sharp on anterior teeth and more blunt on posterior teeth
what affects the shape of the papilla?
- the location of the contact area of the adjacent teeth
- the shape of the interproximal surfaces of adjacent teeth
- the CEJ of adjacent teeth
how can we tell when there is inflammation in the papilla?
easily recognized because papilla takes on:
- a reddened colour
- the tissue becomes puffy
- the apex becomes blunt
- if gingiva appears pink but it is clearly bulbous we write red to identify inflammation
what is the epithelium like in the gingival sulcus?
- nonkeratinized, where the more outer portion is keratinized
what does the gingival groove identify?
- the base of the sulcus if it is visible
how does attached gingiva appear?
often has stippled surface that resembles an orange peel (rete peg formation causes stippling)
what type of epithelium makes up the attached gingiva?
- (keratinized) stratified squamous cell epithelium
what causes the stippling in the attached gingiva?
the rete peg formation, which is created by the irregular binding of the epithelium to bone by collagen fibers giving the look of stippling
what colour is gingiva?
- varies from light to dark depending on the individual’s pigmentation. the darker a person’s skin is, the more apt the tissue will be dark due to melanin.
- healthy gingiva will be pink, more red = likely inflammation. regardless of pigmentation, we still write pink, never brown
what are fibroblasts?
the cells that make up the collagenous fibers of the attached gingiva
what are Sharpey’s fibers?
the fibers that are embedded in the cementum from the papillary tissues. at the ends of connective tissue fibers that are embedded in cementum and bone
what 3 types of fiber group help surround and support the teeth?
1 - gingival fiber group
2 - the transseptal fiber group
3 - the periodontal fiber group
what is the function of the gingival fiber group? (4)
1 - to keep the gingiva closely attached to the tooth surface
2 - assist in preventing the free gingiva from peeling away, and keep the attached gingiva firmly attached
3 - prevent migration of the junctional epithelial attachment (sulcus)
4 - resist recession of the gingiva
there are 4 groups of gingival fibers. what are they used for?
- gingival fibers pass out of the cementum/alveolar bone in small bundles
- they act to support the marginal (free) gingival tissues in relation to the tooth (sphincter like ‘pulling of purse strings’)
- they are located in the lamina propria (connective tissue of the gingiva)
what are the 4 groups of gingival fibers?
1 - dentogingival fibers
2 - alveologingival fibers
3 - dentoperiosteal fibers
4 - circular fibers
what are dentogingival fibers?
extend from the cervical cementum outward and upward into the lamina propria
what are alveologingival fibers?
extend upwards from the alveolar crest into the lamina propria
what are the dentoperiosteal fibers?
extend facially and lingually from the cementum, pass over the crest of bone, and turn apically between the outer periosteum of the alveolar process and the outer epithelium of the attached gingiva
what are the circular fibers?
form a band around the neck of a tooth and are interlaced
what is the transeptal fiber group?
fibers that are just above the alveolar crest of bone that travel completely across the IP space and attach to the cementum of the adjacent tooth
what is the periodontal group?
periodontal ligaments = dense connective tissues organized into fiber groups
- PDL connects the cementum covering the root of the tooth with the alveolar bone of the socket wall
- the fibers are designed to support the tooth in its socket and hold it firmly in normal relationship to the surrounding soft and hard tissues
- the fibers also act as the sensory receptors, necessary for the proper positioning of the jaws during normal functioning
where does the blood supply of the gingival tissue originate? where do those vessels originate from?
in the supraperiosteal vessels. those, in turn, originate from the lingual, mental, buccal, intraorbital and palatine arteries. gingiva is rich in vascularity, as is alveolar mucosa which is redder because of shallower blood vessels
what are the 4 functions of the attachment unit? what do each of these functions do?
- supportive: hold teeth in place
- formative: replace cementum (specialized cells called cementoblasts), PDL (fibroblasts) and alveolar bone (osteoblasts)
- nutritive: supplied by the blood vessels
- sensory: supplied by the nerves which act as an indicator of the pressure or pain around a tooth
what other function does the PDL have?
also acts as a suspensory mechanism for the teeth that cushions the impact between tooth and bone on the exertion of pressure
what are the 2 types of cementum? how does cementum grow?
- acellular: always covers the cervical (coronal) 3rd of the root and extends over the root but not the apical portion
- cellular: like bone in character and covers the apical 3rd of the root
- cementum grows by apposition (addition) of new layers
what is the alveolar process?
- supports the teeth in their functional positions in the jaws
- cortical plate is dense outer covering of the spongy bone that makes up the central part of the alveolar process (hard bone)
what is the alveolar crest?
- the highest point of the alveolar ridge
what is the alveolar socket?
- the cavity within the alveolar process that surrounds the root of a tooth
what is the lamina dura?
- thin compact bone lining the alveolar socket and alveolar crest
what are the 5 periodontal fiber groups?
1 - alveolar crest fibers 2 - horizontal fibers 3 - oblique fibers 4 - apical fibers 5 - interradicular fibers
what are alveolar crest fibers?
retain tooth and resist lateral movement
what are horizontal fibers?
restrain lateral movement
what are oblique fibers?
resist forces to the long axis of the tooth, most numerous fibers
what are apical fibers?
prevent tipping, resist twisting, protect blood and nerve supply
what are interradicular fibers?
- only multirooted teeth (resist tipping and twisting)
what are the 2 forces within the mouth that allow for movement of the teeth? why is this?
- mesial drift (allows forward movement)
- eruption forces (will migrate occlusally until it occludes with an antagonist)
because the PDL allows for movement of the teeth, they have the potential to drift, rotate or be compressed within the alveolus
what clinical consideration do we need to take into consideration regarding the PDLs?
- teeth can move in the alveolar bone
- forces must be present
- osteoclastic and osteoblastic cells are in action: the net effect is that the tooth is moving away from the force by remodelling bone; one side-bone is destroyed, the other is formed
what are the 5 types of forces?
1 - active eruption: compensation for occlusal abrasion
2 - mesial drift: compensation for proximal abrasion
3 - masticatory occlusal forces: tooth occlusion during chewing
4 - orthodontic forces: pressure to fix maloccusion
5 - traumatic occlusal forces: teeth being subject to premature contact during occlusion
what are the consequences of force?
- active eruption and mesial drift cause tipping, drifting and rotation
- occlusal trauma is not a constant consistent force. it does not result in movement as much as it does tooth mobility (the PDL space is widened and can be visible on a radiograph; the tooth can become loose and mobile in the socket)
