Pulp Tissue
-aka Endodontium
-chamber pulp ? aka
coronal pulp
-root pulp ? aka
radicular pulp
-Surfaces = Roof/Floor, M/D, F/L
-CONNECTIVE TISSUE... Derived from Dental Papilla (ectomesenchymal tissue)
-Roof ?contains pulp horns: incisors have # facial developmental
Clinical Significance of Apical Foramen & Accessory Canals
infections that reach the pulp can travel through CT at the apex and destroy PD ligament
Root Pulp
Radicular Pulp (within root canal)
Shape of pulp dictated by...
tooth configuration
Chamber Pulp
Coronal Pulp
Pulp Components
1. Cells
2. Intercellular Substance:
(A) Fibers:
Collagen
(mature) + Reticulum (immature)
(B) Amorphous:
ground substance
(initial repair)
3. Tissue Fluid
4. Blood Vessels: nutrition & Oxygen (salts for 2' dentin)
5. Nerves
6. Lymphatics: remove waste
7.
Denticles
-round & calcified; similar to kidney stones
-non-pathogenic
Diffuse Calcification
-Korff's fiber wanders into the pulp due to odontoblasts
-salts from blood supply collect around the fiber and spread out ? calcify
Pulp Cells
1.
Odontoblasts
: reside in pulp to form 2' dentin
2.
Fibroblasts
: most numerous, star-shape, and responsible for ground substance
3.
Undifferentiated Mesenchymal Cell
: basic cell that can convert into any cell needed by the pulp
4. Defense Cells:
(A)
P
Pulp Function
1. Nutrition
2. Sensory
3. Defense: immune/inflammatory response & 2' dentin
4. Formative: 2' dentin
Pulp Zones
superficial ? deep
1. Odontoblastic Zone
2. Cell-Free Zone: ineffective buffer against bacteria
3. Cell-Rich Zone: fibroblasts, microphages, plasma cells (create B-cells)
4. Blood/Nerves/Lymphatics
Pulp Clinical Significance
1. Extra-Dentin: 2' dentin (salts from pulp collect in tubules in Dentin with destroyed cytoplasm = Sclerotic Dentin)
2. SEVER PULP (blood supply/nerve) form NON-VITAL TOOTH: trauma or orthodontics that are moved too quickly ? blood moves into dentinal tu
Cementum
-forms anatomical root
-Root is divided into 1/2:
(1) Cervical 1/2 ? acellular (
0.01 mm thick
k*)
(2) Apical 1/2 ? cellular (
0.05 mm thick
k*)
-CEJ Configurations:
(A) cementum overlaps enamel (60%)
(B) cementum and enamel meet at a point (30%)
(C)
ceme
Cementum Composition
1. Organic (50%)
(A)
Fiber
(B)
Ground Substance
: keeps fiber healthy
(C)
Lacuna
: space containing cementocyte
(D)
Cementocyte
: the cementoblast resting in lacuna
(E)
Canaliculi
: cytoplasmic projections
2. Inorganic (50%)
(A) Hydroxyapatite
Difference b/w Cementum & Bone
-both are 50 organic/50 inorganic
-cementum doesn't have blood/nerves
-cementum cannot remodel
Cementum Functions
1.
Seal Tubules
: if not present, causes sensistivity
2.
Suspend Tooth in Socket
: PD ligament connects into cementum and bone ? by separating tooth and bone, prevent resorption
3.
Repair/Rebuild
: ONLY in presence of PD ligament... after trauma where the
Sharpey's Fibers
-connect the end of each PD ligament to the cementum
-when bone destruction occurs, forms altered cementum because sharpey's fibers are disconnected but leave remnants on cementum
-forms small pits where bacteria can collect ? must remove toxins by curett
Cementogenesis
-Recall: shape & # of roots is formed by Hertwig's Epithelial Sheet (ameloblast ? reduced enamel epithelium ? HES)
1. Hertwig's Epithelial Sheath forms INTERMEDIATE LAYER (highly mineralized)
2. Dental sac forms PD ligament (CT)
3. PD Ligament forms cemen
Incremental Lines/Layers of Cementum
1.
Intermediate Layer
: deepest layer, adjacent to dentin, oldest cementum, most mineralized
2.
Cementoid Layer
: most superficial layer, adjacent to PD ligament, newest cementum, least mineralized
Clinical Significance
1.
Attrition
: post-attrition, tooth supra-erupts out of socket in order to meet antagonist ? puts
tension
n* on PD ligament causing extra cementum to form on the apex of the root
2.
Orthodontia
: by moving tooth mesially, tooth root causes
pressure
on th
Hypercementosis/Excementosis
extra cementum forming on the root of the tooth due to tension
Ankylosis
anchor tooth in socket
Tension vs. Pressure
1.
Tension
: building cementum in order to ensure stability of tooth in socket
2.
Pressure
: more mineralized structure is resorbed when pressure is applied
CT associated with...
1. Pulp
2. PD Ligament
Periodontal Ligament
-CT that encircles the root
-derived from Dental Sac (ectomesenchyme)
-Intercellular Substance Components:
1. Ground substance
2. Fibers =
Elastic
(mature) +
Oxytalin
(immature) ? different than pulp
PDLS
-Periodontal Ligament Space
-the space visible on radiographs that indicates PD ligament
-MEASUREMENT =
0.12-0.33 mm
PD Ligament Components
Cells:
1. Fibroblasts: star-shaped, responsible for ground substance/initial repair
2. Undifferentiated Mesenchymal Cells
3. Osteoblasts (build bone) + Osteoclasts (resorb bone) ? responsible for Bone Remodeling
4. Cementoblasts (build cementum) + Cemento
Cementicle
-calcified sphere on the PDL
Denticle
-calcified sphere on the pulp
PD Ligament Functions
1.
Nutritive
2.
Sensory
: associated with identifiying
occlusal force
(not pain like pulp)
3.
Formative
: (A) Cementum (B) Alveolar Bone: can be remodeled by the osteoblasts/clasts at surface of the socket
4.
Defense
5.
Supportive
: suspends tooth in sock
Principal Gingival Fibers
FUNCTION =
brace-up the gingival margin
(adhere Free Gingiva tightly to the tooth) to close sulcus
1.
Dentinogingival
fibers = cementum to CT of gingiva (lamina propria)
2.
Dentinoperiosteal
fibers = cementum to periosteum of alveolar bone
3.
Alveologingi
Principal PD Fibers
1-4. Principal Gingival Fibers
5.
Alveolar Crest
: resist horizontal/lateral movement
6.
Horizontal Fibers
: same as above
7.
Oblique Fibers
: opposite angle of alveolar crest, control vertical movement (80% of fibers, most numerous)
8.
Apical Fibers
: pr
PDL Clinical Significance
1.
Cementum Repair
: can only occur if PDL is present to create cementoblasts
2.
PDL/PDLS Arrangement
: use it or lose it (mastication maintains this arrangement); if no antagonist, lose PDL arrangement and narrow PDLS
Intersitial Space
-spaces between PDL
-contains
INTERMEDIATE PLEXUS
Intermediate Plexus
network of blood vessels found within interstitial space
Periodontium
-structures that hold teeth in place
1. Gingival Tissue
2-4. Attachment Apparatus (Root Cementum, Alveolar Bone, PDL)
Attachment Apparatus
1. Root Cementum
2. Alveolar Bone
3. PDL
Alveolar Bone Matrix & Composition
ORGANIC (50%)
1. Collagen Fiber
2. Ground Substance
3. Lacuna + Osteocyte
4. Canaliculi
5. Blood Vessels/Nerves
INORGANIC (50%)
1. Hydroxyapatite
Alveolar Bone Types
COMPACT BONE
1.
Alveolar Crest
: most coronal portion
2.
Cortical Plate
: facial/lingual surfaces
3.
Border of Mandible
: most inferior portion
4.
Alveolar Proper
: lines socket
5. Compact bone covers marrow spaces
CANCELLOUS/TRABECULAR BONE
1.
Red Marrow
Alveolar Process
-bony structure that surrounds/supports the root of the tooth
1.
Alveolar Proper
: compact bone that lines socket
2.
Supporting Alveolar
: cortical plate + internal cancellous bone
Alveolar Bone Configurations
DIAGRAM
1.
Periosteum
: fine CT covering compact bone (req'd for remodeling)
2.
Lamellar Bone
: layers of compact bone
3.
Haversian System
: concentric circles (with Haversian Canal & Volkmann's Canal)
4.
Endosteum
: finer inner CT lining
5. Cancellous Bo
Lamellar Bone
-aka subperiosteal/circumferential
-layers of compact bone that go all the way around maxilla & mandible
-Contain: Lacuna + Osteocyte +Canaliculi
Haversian System
-concentric bone layer circles
-Contain:
1. Lacuna + Osteocyte + Canaliculi
2.
Haversian Canal
: center of concentric circle (runs vertically) that contain blood vessels
3.
Volkmann's Canal
: contain blood vessels (runs horizontally)
Endosteum
-CT that is finer than periosteum
-req'd for remodeling
-Lines:
1. Internal wall of compact bone
2. Haversian Canal
3. Volkmann's Canal
4. Trabeculae of Cancellous Bone (which is technically compact bone)
Alveolar Proper
-compact bone that lines the socket & connects to PDL via Sharpey's Fibers (bundle of fibers)
-called
lamina dura
in radiographs (white line)
-Layers:
1.
Bundle Bone
: superficial layer that Sharpey's fibers connect into
2.
Cribriform Plate
: holes in alv
Alveolar Bone Formation
1.
Endochondral
:
long bone
formation (NOT maxilla or mandible), develops from
cartilaginous model
that mineralizes over time
2.
Intramembranous
: maxilla/mandible formation, CT (mesodermal origin) mineralizes into bone
Bone Remodeling
:
1. Bone Growth (A