Oral Histology: Introduction & Study

Introduction to Oral Histology

• Oral histology uses microscopes for high-magnification tissue study at the cellular and organelle levels, instead of naked eyes.

Why Study Oral Histology and Biology?

• Understanding the structure and function of oral tissues is essential for understanding tissue function.
• Understanding tissue structure and function helps inform treatment approaches.
• Studying oral tissues development aids in understanding tissue-related pathologies.
• This study is important for understanding general oral physiology and oral diseases.

How to Study Oral Histology and Biology

• Gross Anatomy: Macroscopic study with the naked eye.
• Focus on physical properties and reactions to forces from different sources.
• Understand compounds responsible for tissue formation via chemical composition.

Histological Sections

• Oral cavity tissues are divided into hard and soft tissues.
• Hard tissues require ground or decalcified sections for study.
• Soft tissues are prepared with stains like H&E for study

Ground vs. Decalcified Sections

• In ground sections, organic substances are burned, leaving inorganic substances and tissues visible, minus pulp.
• In decalcified sections, inorganic material dissolves, leaving organic material.
• Enamel is dissolved in decalcified sections, leaving a space; dentine and cementum remain due to higher organic content.
• Enamel, cementum, and dentine are hard tissues made from inorganic materials.
• Enamel has the highest percentage of inorganic materials, at 96%.

Oral Structures: Composition

• Teeth consist of enamel, dentine, cementum, and pulp.
• Periodontium includes gingiva, alveolar bone, periodontal ligament, and root cementum, attaching teeth to bone.
• Jaw bones provide a site for teeth via attachment with the periodontium.
• Temporomandibular Joint (TMJ) is also present
• Oral mucosa covering bones with submucosa, which provides a lining.
• The sub-mucosa contains blood vessels and nerves.
• Salivary glands are present.

Oral Structures Classification

• Soft tissues: Pulp, periodontal ligament, oral mucosa, sub-mucosa, salivary glands.
• Hard tissues: Enamel, dentine, cementum, alveolar bone, jaw bones, temporomandibular joint.

Tooth Structure

• Teeth have a crown and root(s) with a pulp chamber and root canal(s).
• Enamel, dentine, pulp tissue, and cementum are the components of a tooth.

Enamel

• Enamel is the most highly mineralized and hardest tissue.
• Enamel consists of 96% inorganic material.
• It is non-vital, lacking blood vessels and nerves, and cannot regenerate.
• Ameloblasts produce enamel, depositing it before dying, which makes enamel non-regenerative.

Dentine

• Dentine forms the bulk of the tooth.
• It is rigid yet elastic for enamel support.
• Dentine protects enamel from breaking because it is rigid and elastic, unlike enamel.
• Enamel covers the crown area, and cementum covers the root area.
• It has a nerve supply, sensitive.
• Dentine is capable of repair.
• During the embryonic stage, odontoblasts are responsible for dentine formation.
• Unlike ameloblasts, odontoblasts remain alive, enabling dentine to regenerate.

Pulp

• Pulp forms, nourishes, innervates, and repairs dentine because odontoblasts are located on pulp's surface.
• Connective tissue contained within pulp chamber (coronal part in the crown) and root canal (radicular part in the root).

Maxilla and Mandible

• The maxilla and mandible have different embryological ossification.

Temporomandibular Joint

• Synovial articulation between mandible and cranium, covered by a capsule.
• Only articulation in the oral cavity and it is vital.

Oral Mucosa

• The oral mucosa lines the oral cavity, including the gingiva.
• It has oral epithelium, underlying connective tissue (lamina propria), and basement membrane.

Oral Sub-Mucosa

• Contains loose fatty or glandular connective tissue.
• Contains major vessels and nerves supplying mucosa and separating it from underlying bones/muscles.

Salivary Glands

• There are three pairs of major and minor salivary glands.
• Major salivary glands include parotid, submandibular, and sublingual glands.

Peridontium

• Teeth are supported by the peridontium which consists of gingiva, root cementum, periodontal ligament, alveolar bone and attaches the tooth to the alveolar bone.

Gingiva

• It is part of the oral muscosa.
• Forms a collar around the tooth coming from all sides (360 degrees).
• 2 regions, attached to the bone and free from attachments.

Root Cementum

• Hard tissue, covering dentine, less hard than enamel or dentine
• Repair and regenerates
• Thin calcified tissue layer covering the surface of the root.

Periodontal Ligament

• Ligaments that attach the cementum and alveolar bone together.
• It is dense fibrous tissue.

Alveolar Bone

• Supports the teeth and consists of outer and inner cortical plates.
• Spongy bone is in the middle.
• Alveolar bone where teeth sit is called the socket.
• Individual sockets are separated by inter-dental septa.
• It is comprised of spongy and compact bone histologically.