Anatomy - Week 9 PP Flashcards
What is the periodontium consist of?
The periodontium consists of..
- cementum
-periodontal ligaments
-alveolar bone
-gingival - more of a minor role
Cementum Characteristics
-part of the periodontium that attaches the teeth to the alveolar process by anchoring the periondtal ligaments (PDL)
-hard dental tissue that covers the root and joins the enamel at the CEJ
- softer than dentin
Cementum physical characteristics
colour: yellowish - clinically looks like dentin
Thickness: 1 hair (16-60 microns) in coronal half
thicker in apical half (150-200 microns)
Resistance: may be removed by brushing, decays easily
Chemical composition of cementum
65 % inorganic substance
23% organic substance (proteins)
12 % water
Histological Structure of Cementum
- Composed of a mineralized fibrous matrix and cells
- Cementoblasts (come from dental sac) ◦ Found in the periodontal ligament (PDL) ◦ Form cementum ◦ Some become embedded in the cementum –become
cementocytes ◦ The cementocytes are housed in a lacunae and have
canals (canaliculi) ◦ Canaliculi are oriented towards the PDL and have a
cementocyte process that derive nutrients for the PDL
Sharpey’s Fibers
- Ends of the fibers of the PDL that become trapped in the developing cementum
- Attach the PDL firmly to the tooth and suspend the tooth in the socket
Formation of Cementum
- Forms in Layers
◦ Cementoblasts in the PDL start at CEJ and move
downwards secreting a ground substance for the full
length of the tooth
Ground substance eventually calcifies Towards apex, cementoblasts become trapped in the calcifying
cementum making it a thicker layer - three relationships with enamel and dentin
-1. Overlaps Enamel at CEJ – 15%
-2. Meets Enamel at CEJ – 52%
-3. Does not meet Enamel at CEJ – 33%
* Cause of sensitivity
* Exposing dentinal tubules
*decided by genetics - Accellular cementum
◦ First layer of cementum deposited at the DCJ ◦ Also considered primary cementum
◦ Has no embedded cemetocytes
◦ At least one layer of acellular cementum covers the entire tooth
◦ Thin cementum in coronal ½ to 1/3 of the tooth - Cellular Cementum
◦ Sometimes called secondary cementum
◦ Apical portion of the tooth
◦ Thicker, contains cementocytes Allows for the production of more cellular cementum
Clinical Importance of Cementum
- more succeptible to decay if there is recession
- Anchors tooth to bony socket * PDL fibers suspend the tooth into the socket * Connect cementum to bone
- Through Sharpeys fibres
- No cementum
- no attachment
NO CEMENTUM = NO ATTACHMENT
Compensates for loss of enamel
* Produces intermittently throughout life of tooth
* Due to occlusion/attrition
* Adding of layers of cementum at root apex
* Keep max and mand teeth in contact/occlusion
* Very slight movement occlusally
* Causes natural gingival recession
(overeruption - when there is no opposing tooth in other arch)
Clinical Importance of cementum.. continued
-Repairs damaged tooth root
-Replaces resorbed dentin due to trauma
-Examble - 3rd molar impacted
-pushing on tooth
- can cause resorption of bone and root of tooth in front
Clinical Considerations for Cementum
-Resporption of the cementum at the apex of the roots on maxillary anteriors can occur with trauma such as with rapid orthodontic movement
- May cause tooth mobility due to root resorption
During Cementum Formation
* Hypercementosis/Cementum Hyperplasia
Thickening of cellular cementum
At the root apex Causes no problem unless being extracted
Periodontal Ligaments
The PDL is part of the periodontium that provides for the attachment of the teeth
to the surrounding alveolar bone by way of the cementum
- Connective tissue around the root of the tooth
◦ Peri = around
◦ Odontos = tooth - Main suspensory tissue of periodontium
◦ At root: cementum to bone
Sharpey’s fibers: bundles of collagen fibers
trapped in cementum
◦ At cervical of tooth: Connective tissue of gingiva
PDL Formation
Forms from the Dental Sac - process begins after cementum formation begins > Fibroblasts > Intercellular substance > collagen > periodontal ligament
PDL: Other components
- Cementoblast * Osteoblasts
- Nerves
◦ Sensory nerves Provides sense of touch - Rests of Malassez: small groups of epithelial cells
◦ Remnants of Hertwig’s root sheath during development ◦ May have a role in formation of cysts/tumors - Cementicles: small calcified bodies in the PDL
◦ No clinical significance - Specialized cells
◦ Osteoclasts, osteoblasts which react to the demands of the
adjacent environment (bone)
PDL: Principal fiber groups
- Gingival fibers
- Transseptal fibers
- Alveolar crest fibers
- Horizontal fibers
- Oblique fibers
- Apical fibers
- Interradicular fibers
Gingival Fibres
- Location: cervical part of root
- Connection: tooth to gingiva
- Extends into interdental papilla
- DO NOT insert into the alveolar bone
- Purpose: holds gingiva close to tooth
- Pulled tight with incisal/occlusal forces
- takes you from tooth to gingiva
-purpose is to hold gingiva close to tooth
-fibers extend from cementum into the gingiva
Transseptal Fibers
- Location: apical to the gingival fibers
- Only on mesial and distal surfaces
- Connection: tooth to tooth via cementum
- Purpose: ensures teeth remain in proper relationship to one another and support the
interproximal gingiva - cementum from one tooth to cementum to the next tooth
-helps keep teeth in the right positon
-No bone!
Alveolar Crest Fibres
- very top of the alveolar bone (crest means top!)
-inserts into the bone
-fibers reaching right from the cementum to the top of the bone
-purpose is to resist horizontal movements of the tooth - Location: at level of alveolar crest
- Margin of bone around tooth root * All around the tooth
- Connection: cementum to bone
- Tooth root to alveolar crest
- Purpose: resists horizontal movements and maintain tooth in socket
Horizontal Fibers
- go horizontally from cementum to bone
-resisting horizontal pressures
-just under alveolar crest fibers - Location: apical to alveolar crest fibers
- Connection: cementum to bone
- Purpose: resists horizontal (lateral) pressures applied to crown of tooth
Oblique
-Slanted fibers
-resisting up and down forces on teeth
- Location: apical to
horizontal fibers - Connection: cementum to bone
- Purpose: resist forces places on the long axis of the tooth
Apical fibers
- Location: around apex of
tooth - Connection: cementum to
bone * Purpose: * Prevent the tooth from
tipping - Resist twisting (luxation) * Protect the blood,
lymph and nerves
supply to the tooth
-closer to apices of the tooth
-right under oblique, closer or attached to apex of the tooth
-help to prevent tooth from tipping from one direction or another
-help supply nerve and blood vessels to the tooth
-help prevent twisting of the tooth
Interradicular fibers
in between the furcation of roots
- helps with stabalizing (no tipping, twisting)
-only the tooth that have two or more roots (or a furcation)
* Location: in the furcations between roots
* Connection: cementum to bone
* Tooth root to interradicular septum
* Purpose: stabilize tooth (resist tipping and tilting
PDL Functions
- Supportive
Transmits occlusal forces from teeth to the
bone allowing for small movement Shock absorption - Formative
◦ Throughout life
◦ Tension (pull) on PDL cementum+bone formation - Resorptive
* Pressure on PDL
becomes narrower
* Severe pressure can cause
* Bone resorption
* Cementum resorption
* Destroys PDL
Ortho is controllled trauma - Sensory
◦ Determines pressure and touch
Pain determined from tooth pulp - Nutritive
◦ Presence of blood vessels provide essential nutrients to area
Clinical Considerations for the Periondtal Ligament
Main purpose is to anchor tooth in socket
Maintains the gingival tissues in proper relationship to the teeth
transmits occulsal forces from the teeth to the bone (shock absorber) Cells found within contribute to the development and resorption of the hard tissues of the periodontium
Blood vessels within provide nutrients Nerve supply – sensation of pressure
Peridontal disease and PDL?
Periodontal Disease can cause destruction of the PDL fibers causing tooth mobility
Occlusal Trauma
- The PDL will widen in response to occlusal trauma
- Thickening of the lamina dura is also possible with early occlusal trauma.
- This will appear in xrays
- Clinically, occlusal trauma is noted by the late manifestation of increased mobility of the tooth.
- Clinically, occlusal trauma is also noted possibly by the presence of pathological tooth migration (PTM). If you have spacing throughout dentition it is not always due to disease but typically it is something pathological meaning it can be problematic. (Sometimes ppl have natural spacing between teeth with healthing gums, no pockets, etc)
Orthodontics
- To a lesser extent, orthodontic therapy also affects the PDL similar to its response to occlusal trauma or periodontal disease but in a more controlled manner.
- On the side under tension, the periodontal ligament space will become wider; on the side under pressure, it will become narrower.
- The interdental ligament is also responsible for the memory of tooth positioning within each dental arch.
essentially you are destroying PDL, by putting tension on it.. and build up bone on other side.. There is memory in fibers so you will have to wear a retainer to keep them from going back to original place
Alveolar Process
- The alveolar process is the part of the maxilla or the mandible that supports and protects the teeth
- Part of the periodontium to which the cementum of the tooth is attached through the PDL
- Hard mineralized tissue with all the other components of other bone tissues
◦ Connective tissue
◦ Made of Osteocytes (bone cells)
Organic matrix that mineralizes
Its what teeth is attached to, connective tissues made of osteocytes (bone cells).
similar in composition to cementum
60 % in organic
25 % organic
15% water
Characteristics of Alveolar Bone
Alveolar Bone (Process)
* Makes up the lining of the tooth socket
- Lamina Dura
(cribiform plate) – part of the alveolar bone that is uniformally radiopaque - Alveolar Crest – the most cervical part
Supporting Alveolar Bone
- Cortical bone
A plate of compact bone on both the facial and lingual surfaces of the alveolar process - Trabecular/Spongy bone
Consists of cancellous or spongy bone that is located between the alveolar bone and the plates of cortical bone
Bone Cells
- Osteocytes: bone cells
- Osteo = bone
- Cyte = cell * Lacunae: “little spaces”
- Where osteocytes are located
- Canaliculi: “little canals”
- Connect lacunae-tolacunae
Bone: Nutrient Transport
◦ Very vascular = high blood supply
◦ High communication through many canals and
systems
◦ Haversian Canal System
Carries blood supply (veins and arteries)
Bone Connective Tisse Coverings
- Periosteum
◦ Tough connective tissue
◦ Outside of bone - Endosteum
◦ Delicate connective tissue
◦ Location:
Inner surface of compact bone
Surface of trabeculae
Lines Haversian and Volkmann’s canals
Bone Growth
- Formation and resorption is a process
◦ Occurs throughout life
◦ Intermittent
Formation: New bone forms from periosteum or endosteum
Osteoblasts form bone
Resorption: removes mineral and organic matrix of bone
Osteo-: bone
-Clasts: to break
Clinical Considerations for Alveolar Bone - Orthodontics
- The bands, wires, or appliances put pressure on one side of the tooth and adjacent alveolar bone, creating a compression zone in the PDL.
- This compression in the PDL leads to bone resorption.
On the opposite side of the tooth and bone, a tension zone develops in the PDL and causes the deposition of new bone
Pull, move, push..
Clinical Considerations for Alveolar Bone - Mesial Drift
- Mesial drift, or physiological drift, is a
normal, natural
movement phenomenon
in which all the teeth
move slightly toward the
midline of the oral cavity
over time. * This can cause crowding,
late in life, in a onceperfect dentition - normal for most individuals, teeth tend to move toward the mesial (except if you have a diastema) typically seen as a result of crowding
-if you have molars, and the 6th is gone, the 7th will tilt move into position of the 6th - this is mesial drift
Clinical Considerations for Alveolar Bone - Periodontal Disease
- Bone loss caused by chronic periodontal disease or periodontitis.
Level of Alveolar bone
we expect the alveolar bone to be 2-3 mm below the CEJ
Clinical Considerations for Alveolar Bone - Density of bone
- The density of the alveolar bone in an area also determines the route that dental infection takes with abscess formation,
- as well as the efficacy of local infiltration during the use of local anesthesia.
Clinical Consideration for Alveolar Bone - Tooth Loss
- After extraction of a tooth, the clot in the alveolus fills in with immature bone, which later is remodeled into mature secondary bone.
- However, with the loss of teeth, a patient becomes edentulous, either partially or completely, and the alveolar bone undergoes resorption
- for older patients, we want them to massage area (where teeth are lost) to keep blood flow there so the bone doesn’t get lost too quickly
- dentures are often uncomfortable, hard to fit.. due to the changing of the alveolar bone
Clinical Consideration for Alveolar Bone - Implants
Ideally, an implant placed in an edentulous area preserves the integrity of the bone and
serves as a permanent replacement for a lost tooth or teeth, preventing loss of vertical dimension
typically not a good canditate if alveolar bone lost
Disease Process
- Itis = inflammation
-Perio means around
if gingivtis doesn’t get treated it can develop into more sever diease - periodontist which is irrevrsabile
- Each tooth has a socket or alveolus
- prtecting the socket is sthe gingiva,
root sits in the alveolus
-Cementum covers the root
-Neck is the section between the root and the crown
- enamel is hardest substane in human body
-free gingiva is the gingiva not attached to tooth
- giginval crevicular fluid between free gingiva and tooth
- State of inbalance = gigivitis and periodontitits
-
3 Types of Mucosa
- Masticatory
- Lining
- Specialized
The Normal Periodontium
I. Gingiva
A. Free Gingiva (Marginal Gingiva)
B. Gingival Sulcus (Crevice)
C. Interdental Gingiva (Interdental Papilla)
D. Junctional Epithelium
E. Attached Gingiva
F. Mucogingival Junction
G. Alveolar Mucosa
Gingival of Young Children - Primary Dentition
- Color: pink
- Shape: thick, rounded or rolled
- Consistency: less fibrous than adult – not as tightly adapted
- Texture: may or may not have stippling
Gingiva of Young Children - Mixed Children
- Constant state of change – periods of inflammation related to exfoliation and eruption
- Free gingiva: rounded or rolled, slightly reddened, shiny and a lack of firmness
Gingivitis occurs frequently
Gingival Observations - signs of disease
- Signs of disease ◦ May be localized or limited to specific areas or generalized throughout the gingiva
◦ Compare the free gingiva (marginal and interdental) to the attached gingiva
◦ Degree - mild, moderate or severe
Gland Properties - exocrine gland
- A gland is a structure that produces a secretion necessary for normal body functioning. * An exocrine gland is a gland having a duct associated with it.
- A duct is a passageway that allows the glandular secretion to be emptied directly into the location where the secretion is to be used
Gland Properties - endocrine gland
- An endocrine gland is a ductless gland with its secretions conveyed directly into the blood and then carried to some distant location to be used.
- Motor nerves associated with both types of glands help regulate the flow of the secretion.
- Sensory nerves are also present in the gland
Salivary Glands
- The salivary glands produce saliva, which lubricates and cleanses the oral cavity and aids in
the digestion of food through an enzymatic process - Saliva also helps maintain the integrity of tooth surfaces through a process of remineralization
- Salivary glands are classified by their size as either major or minor
Salivary Gland Properties
- Saliva contains minerals, electrolytes, proteins, buffers, enzymes, immunoglobulins (secretory IgA), and metabolic wastes.
- The secretion by these glands is controlled by the autonomic nervous system.
- Saliva lubricates and cleanses the oral mucosa, protecting it from dryness and potential
carcinogens by way of its mucins and other glycoproteins
Two Types of Saliva
- Serous
◦ Watery
◦ Mainly protein - Mucous
◦ Very thick
◦ Mainly carbohydrate
Major Salivary Glands - Parotoid Salivary Gland
- Parotid salivary gland
◦ Saliva passes from the parotid gland into the mouth through a duct called the parotid duct (also known as Stensen’s duct) - the largest major salivar gland, it provides only 25% of the total salivary volume
Location: It is located in an area behind the mandibular ramus, anterior and inferior to the ear
- Duct is Parotid Duct (stensons duct)
- calculus build up can happen in area of 1.6/1.7/2.6/2.7 because of this gland being there
Major Salivary glands - Submandibular salivary gland
◦ Releases saliva into the oral cavity through Wharton’s
duct, which ends in the sublingual caruncles
- The second-largest major salivary gland, but it provides 60% to 65% of the total salivary volume
Location: it lies beneath the
mandible in the submandibular fossa, posterior to the sublingual salivary gland
Duct - submandibular duct
If something sour on your tongue, this gland will release saliva into your mouth
Major salivary Gland - Sublingual Salivary Gland
- Sublingual salivary gland
◦ Releases saliva into the oral cavity through the sublingual duct (also known as Bartholin’s duct
The smallest, most diffuse
It provides only 10% of the total salivary volume
Location: This gland is superior to the mylohyoid muscle and medial to the body of the mandible
The sublingual gland is also anterior to the submandibular gland .
Sublingual Ducts
- The sublingual glands are drained by 8-20
excretory ducts called the ducts of Rivinus. * The largest of all, the sublingual duct (of Bartholin)
joins the submandibular duct to drain through
the sublingual caruncle. * Most of the remaining small sublingual ducts (of
Rivinus) open separate into the mouth on an
elevated crest of mucous membrane, the plica
sublingualis (aka sublingual fold), formed by the
gland and located on either side of the frenulum
linguae
Minor Salivary Glands
- Smaller and more numerous than the major salivary glands
- Scattered in the tissues of the buccal, labial, and lingual mucosa; the soft palate; the lateral portions of the hard palate; and the floor of the mouth
- Ebner’s salivary gland is associated with the large circumvallate papillae on the tongue
Disorders of the Salivary Glands
- Xerostomia (dry mouth)
◦ Can result in an increase in dental decay and problems in speech and chewing - Salivary stones (sialoliths)
◦ May block duct openings, preventing saliva from flowing into the mouth
-opening blocked by mineralizations - sometimes better on their own, sometimes must be removed
Thyroid Gland Properties
-the largest endocrine gland
-the thyroid gland produces and secretes its products or hormones directly into the blood, such as thyroxine
- thyroxine is a hormone that stimulates the metabolic rate
Thyroid condition is a medical alert - likely due to the medication they will be taking
Most at risk gland when taking xrays
Thyroid Gland Location
- The gland is in the anterior and lateral regions of the neck.
- The gland is inferolateral to the thyroid cartilage, at the junction between the
larynx and trachea. - The gland consists of two lateral lobes connected anteriorly by an isthmus
Lymphatics Properties
- The lymphatics are a part of the immune system and help fight disease processes.
- They also serve other functions in the body.
- The lymphatic system consists of a network of lymphatic vessels linking lymph nodes throughout most of the body.
- Tonsillar tissue located in the oral cavity and pharynx is part of the lymphatic system
- runs the same as your blood, but is filled with immune response cells (instead of blood cells)
- when a patient has an infection, or cancer the lymph nodes will increase in size
Lymphadenopathy
- When a patient has an infection or cancer in a particular region, the lymph nodes in that region will respond by increasing in size and becoming very firm
- Lymphadenopathy results from an increase in both the size of each lymphocyte and the overall cell count in the lymphoid tissue
- With an increase in the size and number of lymphocytes, the body is better able to fight the disease
Lymphy Nodes of the Head and Neck
- A dental professional must examine and palpate the lymph nodes of the head and
neck very carefully during extraoral examination - Enlarged lymph nodes may indicate infection or cancer * The lymph nodes for the oral
cavity drain intraoral structures, such as the teeth, as well as the eyes, ears, nasal cavity, and deeper areas of the throat
Structure and Function of Lymph Nodes
- Lymph nodes are small and round or oval structures located in lymph vessels
- The major sites of lymph nodes include:
◦ Cervical (in the neck)
◦ Axillary (under the arms)
◦ Inguinal (in the lower abdomen) - The lymph nodes of the head are classified as superficial (near the surface) or deep
Superficial Lymph Nodes of the Head
- There are five groups of superficial lymph nodes in the head
◦ Occipital - behind your head
◦ Retroauricular - ears
◦ Anterior auricular -
◦ Superficial parotid
◦ Facial nodes
Deep Cervical Lymph Nodes
- The deep cervical lymph nodes are located along the length of the internal jugular vein on each side of the neck, deep to the sternocleidomastoid muscle
