Periodontium Flashcards
What is the cementum made up of?
50% Hydroxyapatite crystals. 50% organics and water.
What are the two types of cementum?
- Acellular (primary) Thin acellular layer next to dentin
2. Cellular: Thicker, mostly along apical root.
What is Intermediate cementum? Formed by?
First cementum, also called cementoid. Formed by inner epitheliual root sheeth cells during root dentin formation.
How is Acellular Cementum formed? Function?
Cementoblasts form cementum, and then cementoblasts migrate into Periodontal ligament, leaving the Acellular layer. Provides attachment for the tooth.
How is cellular cementum formed? Function?
Cementoblasts become embedded in the matrix as cementocytes. Helps adapt to tooth wear and repair periodontal ligament.
What are cementocytes?
They are cementoblasts that have lost their ability to secrete and enclose themselves in a matrix.
How does the root develop?
The cervical loop grows deeper enclosing more of the dental papilla forming Hertwigs Epithelial Root Sheath. HERS disintegrates and cementum forms.
The Hertwigs sheath fragments into what?
- Epithelial cells Rests of Malassez
- Fibroblasts in the periodontal ligament
- Osteoblasts in alveolar bone
What is an enamel pearl?
Defect in the Hertwigs.
Where does the Periodontal Ligament formed from? This also forms what?
Ectomesenchyme from within the dental follicle.
- Collagen fibers
- Sharpey’s fibers
What do fibroblasts do?
Make and break down collagen.
Name the fibers and Function of the dentoalveolar principle fibers of PDL.
- Apical: Resist vertical forces
- Oblique: Resist vertical/intrusive forces
- horizontal: Resist horizontal/tipping forces
- Alveolar crest: Resist vertical.intrusive forces
- Interradicular: Resist vertical/lateral movement
Name the fibers and functions of the Gingival principle fibers of PDL.
- Transseptal: Resist movement mesial distal.
- Circular: forms band around tooth
- Dentogingival: Extend cervical cementum to lamina propria of attached and free gingiva.
- Alveogingival: Extend bone of alveolar crest to lamina propria
- Dentoperiosteal: Run apically over periosteum of outer cortical plate into vestible or floor of mouth.
What are Sharpey’s Fibers?
Collagenous fibers embedded in cementum and alveolar bone.
What is the Alveolus?
Tooth socket.
What is the Alveolar Bone proper? Also known as?
Bone lining the tooth socket. Also known as Lamina Dura or Cribiform plate.
what are some special features of the Alveolar bone proper?
Has a lot of holes for blood vessels. remolded constantly according to occlusal forces
WHat is bundle bone? What happens here?
Inner lining of Alveolar bone. Site where PDL fibers (sharpeys) connect into the bone.
WHat is the cortical plate? Thinner and Ticker where?
compact bone that extends over the buccal and lingual aspect of the maxilla and mandible. Thinner in Maxilla, thicker in Mandible.
What are Osteons?
Haversian canals (system) in compact bone.
What are Volkmann’s channels?
Small channels that house blood vessels between the periosteum and bone of cortical plate and communicate with Haversian canals.
What is the alvolar crest (septa)?
The surface nearest the CEJ.
What is Trabecular bone?
Cancellous or spongy bone with haversian systems.
What are the types of trabecular bone?
Types 1-4, with 1 being most dense, and 4 being least dense.
