Dental Anatomy and Periodontology

Physiology of Teeth and Supporting Structures

• Teeth are crucial for mastication, aiding in food reduction and incision.
• Teeth support themselves within dental arches by participating in the development and protection of supporting tissues. An example is physiological mesial drifting.
• Tooth anatomy distinguishes a crown, neck, and root.
• The enamel is the hardest outer layer of the tooth.
• Dentin is beneath the enamel, making up most of the tooth structure.
• The pulp is the soft tissue within the tooth, containing nerves and blood vessels.
• Tooth cementum covers the root.

Tooth Anatomy

• The crown is the visible part of a tooth.
• The anatomic crown extends below the gum line.
• The clinical crown is what's visible.
• Crown size varies.
• Anterior teeth have incisal edges, while posterior teeth have cusps.
• Incisors are for cutting and punching food during mastication.
• Canines, or cuspids, are for shearing and tearing food, supporting incisors and premolars.
• Premolars (bicuspids) are used to grind food.
• Molars have multiple cusps for grinding and trituration of food.
• Roots are covered in cementum, with varying lengths and numbers depending on tooth size and function.
• Teeth are classified as single-rooted (incisors, canines, and certain premolars) or multi-rooted (molars).

Protective Functional Forms of the Tooth Crown

• Proximal contact area (PCA) assures one tooth contacts another mesially and distally.
• PCA prevents food from packing between teeth.
• It stabilizes dental arches via the combined anchorage of all teeth.
• PCA can be viewed via labial/buccal and incisal/occlusal aspects.

Interproximal Space

• Interproximal spaces are triangular shapes between teeth, usually filled with gingival tissue.
• A typical separation of 1-1.5 mm exists between enamel and alveolar bone.

Embrasures

• Spaces created by the curvature of adjacent teeth are termed embrasures.
• Embrasures provide pathways for food during mastication to escape.
• They prevent food from being trapped between teeth.

Cervical Ridges

• Facial and lingual contours of the cervical third of teeth create cervical ridges.
• Typically, the curvature is roughly 0.5 millimeters from the cementoenamel junction (CEJ) to the contour.
• Cervical ridges hold the gingiva under tension and deflect food away from gingival margins.
• Insufficient or excessive curvature may cause gum recession or food packing, respectively.

Supporting Structures

• The supporting structures of a tooth include the periodontal ligament, cementum, alveolar process, pulp, and gingiva.

Periodontal Ligament

• A dense connective tissue that anchors the tooth to the alveolar bone.
• It ranges between 0.1-0.25mm thick.
• It provides shock absorption to manage occlusal forces and prevent tooth breakage.
• It's involved in formative reactions, activating osteoblasts, cementoblasts, and fibroblasts for bone/tooth maintenance.
• Contains sensory nerve endings for pressure assessment and tooth identification during chewing.

Blood Supply of Periodontal Ligaments

• Blood supply arises from alveolar artery branches.
• Additional supply from interradicular and gingival vessels.
• Vessels nourish the crestal area.

Periodontal Fiber Groups

• Transseptal fibers connect adjacent tooth cementum.
• Alveolar crest fibers extend obliquely from the cementum and reach the alveolar crest.
• Horizontal fibers run at right angles to the tooth's long axis through cementum and bone tissues.
• Oblique fibers compose a major group, running obliquely from cementum to bone.
• Apical fibers stem from the apical cementum to the base of the socket.
• Interradicular fibers span furcations in multi-rooted teeth.

Cementum

• A mineralized connective tissue covering tooth roots.
• It contains cementoblasts, cementoclasts, and cementocytes.
• It's essential for anchoring periodontal ligament fibers to the tooth.

Classification of Cementum

• Cementum is classified based on location (radicular, coronal), cellularity (cellular, acellular), and collagen fibril presence (fibrillar, afibrillar).

Types of Cementum

• Acellular fibrillar cementum covers the crown portion, lacking cells.
• Cellular fibrillar cementum covers the root portion, possessing cells.

Developmental and Acquired Anomalies Associated with Cementogenesis

• Anomalies involve enamel projections, enamel pearls, cementicles, and hypercementosis.

Alveolar Bone

• This jawbone part supports and houses teeth.
• Consists of osteoblasts (bone-forming cells), osteoclasts (bone-resorbing cells), and osteocytes.

Parts of Alveolar Bone

• Alveolar bone proper directly surrounds tooth roots, forming a thin lamella.
• Supporting bone envelops the alveolar bone proper, enhancing its functional role.

Bone Cells

• Cells involved in bone formation and structure include osteoblasts, osteoclasts, and osteocytes.

Pulp

• Pulp is a vascular connective tissue contained within dentin walls.
• It encompasses fibroblasts for collagen formation, odontoblasts, and defensive cells.

Functions of the Pulp

• Formative (forming new dentin).
• Nutritive (providing nourishment).
• Sensory (detecting stimuli).
• Defensive (protecting against pathogens).

Composition of Pulp

• Cells comprise fibroblasts, odontoblasts, and defensive cells (e.g., histiocytes, leukocytes).
• Pulp's ground substance consists of proteins and glycosaminoglycans.

Pulp Response to Aging

• Age-related pulp changes include reduced cellular components, dentinal sclerosis, decreased blood vessel quality, decreased pulp size, increased collagen fiber thickness, and pulp stone/dystrophic mineralization increases.

Gingiva

• Gingiva is a part of the oral mucosa covering alveolar processes and surrounding tooth cervical regions.

Regions of Gingiva

• Marginal gingiva (free gingiva): borders teeth like a collar.
• Attached gingiva: tight to the alveolar periosteum.
• Interdental papilla: fills spaces between adjacent teeth.

Layers of Gingival Epithelium

• Oral epithelium: outer layer encompassing crest and superficial attached gingiva; keratinized.
• Sulcular epithelium: non-keratinized, lining gingival sulcus.
• Junctional epithelium: non-keratinized band attaching gingiva to tooth; reinforced by gingival fibers.
• Gingival epithelium varies throughout.

Groups of Gingival Fibers

• Denotgingival, Dentoperiosteal, Alveologingival, Circular, Semicircular and Transseptal fibers.

Lamina Propria

• A connective tissue component of gingiva, rich in collagen.
• It contains papillary and reticular layers to interact with underlying bone or epithelial.

Morphology of Gingiva

• Color: primarily coral pink, may have pigmentations from melanocytes (brown or purple).
• Contour: shaped by various factors, resembling a scalloped line.
• Consistency: firm and resilient in attached gingiva.
• Texture: often stippled, a bumpy surface characteristic of health, may vanish with gingivitis.
• Location: typically at the cementoenamel junction (CEJ).

Questions cover dental anatomy and periodontology, including proximal contact areas, crown types, tooth support, root characteristics, periodontal fibers, cementum function, alveolar bone, dentin origin, furcation involvement, pulp structures, and fiber groups.