Dental Pulp - Dr. Dina M. Makawi PDF

DENTAL PULP Dr. Dina M. Makawi Msc, PhD Lecturer of Oral Biology Room#S33  INTRODUCTION Definition Outline Morphology Histological Structure Function and Age changes  Definition ◦ The dental pulp...

DENTAL PULP Dr. Dina M. Makawi Msc, PhD Lecturer of Oral Biology Room#S33  INTRODUCTION Definition Outline Morphology Histological Structure Function and Age changes  Definition ◦ The dental pulp is a specialized loose delicate connective tissue occupying the cavity in the center of each tooth. MORPHOLOGY  Morphology ØThe coronal pulp: it is present in the pulp chamber. ØIt is composed of wide part called pulp chamber, showing extensions towards the incisal edge or cusps tip called pulp horns. ØThe radicular pulp: It is the extension of the pulp into the root which tapers gradually to end at the apical foramen.  Morphology ØThe apical foramen: The pulp tissue are continuous with the periapical tissue through the apical foramen  Morphology ØDuring the root formation, the apical foramen is wide. ØBy age the root canal and the apical foramen decrease in size due to cementum and dentin deposition.  Morphology ØThe apical foramen: Maxillary teeth Mandibular teeth 0.4mm 0.5 mm  Morphology ØAccessory Canals: ◦ They are commonly seen to extend from radicular pulp laterally through the root dentin to the periodontal ligament. ◦ They are numerous in the apical third of the root.  Morphology ØAccessory Canals (Mechanism Of formation): 1- It occurs in areas, where the developing root encounters a large blood vessel, where dentin will be formed around it. 2- Early degeneration of the epithelial root sheath of Hertwig before the differentiation of the odontoblasts. 3-Lack of complete union of the Tongue- like processes at the floor of the pulp chamber. HISTOLOGY OF THE PULP Histology of the pulp The dental pulp is formed of specialized loose connective tissue: 1. Cells 2. Fibers 3. Intercellular Substances 4. Blood vessels and Nerves The pulp cavity exhibits four zones as you progress from the dentin-pulp junction toward the center of the pulp cavity Pulp Zones 1- Odontogenic zone: Odontoblastic zone 1 Cell free zone Cell rich zone 2 2- Pulp core 1-Odontogenic zone: A- Odontoblastic zone: Adjacent to the pre-dentin with the cell bodies in the pulp and the cell processes in the dentinal tubules. B- cell free zone : - It is present beneath the odontoblastic layer and known as zone of Weil. - It contains the sub-odontoblastic plexus of nerves and capillaries. - It is suggested to be the area of mobilization and replacement of odontoblasts. - More prominent in coronal pulp than in radicular pulp.  C- cell rich zone: It is present beneath the cell free zone. It is composed of fibroblasts and undifferentiated mesenchymal cells. C- cell rich zone:  Cells of the pulp 1- Synthetic cells (formative cells): Odontoblasts and Fibroblasts. 2- Defensive cells: Macrophages, lymphocytes, eosinophils, mast cells and plasma cells. 3- Progenitor cells: Undifferentiated mesenchymal cells. 1- Synthetic cells: a- Odontoblasts ◦ Found as single layer at the pulp periphery, sending their cell processes (odontoblastic process) in dentinal tubules. ◦ They are attached to each other by desmosomes. Odontoblasts are : columnar in the crown cuboidal in root, flat at the root apex  b- Fibroblasts ◦ These are the most numerous type of pulp cells. ◦ They are spindle in shape. ◦ They have elongated processes which connect with those of other pulpal fibroblasts (stellate appearance). b- Fibroblasts ◦ These cells have a dual function: synthesis and degradation of fibers and ground substances by the same cell. b- Fibroblasts ◦ In young pulp, they are : ◦ Large cells. ◦ with large multiple processes ◦ centrally located oval nucleus, ◦ numerous mitochondria, ◦ well developed Golgi bodies ◦ well developed RER b- Fibroblasts In periods of less activity and aging they appear smaller and round or spindle-shaped with few organelles, then they are termed fibrocytes. 2- Defensive cells: A- Histiocyte (macrophage): ◦ They appear irregular in shape with short blunt processes. ◦ The nucleus is small, more rounded & darker in staining than fibroblast. ◦ Play role in defense mechanism & can engulf foreign bodies and bacteria. b- Plasma cells: ◦ These cells are seen during inflammation. ◦ The nucleus of this cell is small an appears eccentric in the cytoplasm. ◦ The arrangement of chromatin in the nucleus gives the cell a cart-wheel appearance, ◦ The plasma cells are known to produce antibodies.  c- Lymphocytes: ◦ They show great variation in size and shape. ◦ In normal pulps, T lymphocyte is found but B lymphocytes are few. ◦ The smaller one has darkly stained rounded nucleus with little cytoplasm. While the large cells have an eccentric kidney shaped nucleus.  D- Eosinophils: ◦They are found in normal pulp and they increase during inflammation. E- Mast cells: *They have a round nucleus and their cytoplasm contains many granules. *They produce histamine& heparin. 3- Progenitor cells: (UMC): ◦ They are smaller than fibroblasts but have a similar appearance. ◦ They are usually found along the walls of blood vessels. ◦ These cells have the potentiality of forming other types of formative or defensive cells. The ground substances of the pulp *The ground substances consists of acid mucopolysaccharides and neutral glycoprotein. *These substances are the environment that promotes life of the cells. NERVES OF THE PULP Nerves Of The Pulp ◦ The pulp is richly innervated. Nerves enter the pulp through the apical foramen, along with afferent blood vessels, and together form the neurovascular bundle.  Nerves Of The Pulp ◦ Two types of nerve supply: 1- Autonomic sympathetic nerve fibers They act to regulate the blood flow in the capillary network of the large blood vessels and control their contraction and dilatation. 2- Sensory Nerve Fibers: - They are afferent sensory fibers, originate from the maxillary and mandibular branches of the trigeminal nerve. - Involved in the perception of pain (the only identified sensation, as those nerves cannot differentiate between heat, touch, pressure, or chemicals, they translate all those different sensations as Pain)  Nerves Of The Pulp ◦ Sensory nerves branches contribute to an extensive plexus of nerves in the cell-free zone of the pulp just below the cell bodies of the odontoblasts in the crown. ◦ This plexus of nerves is called the sub-odontoblastic plexus of Raschkow or the parietal layer of nerves. o The plexus of rashckow: LARGE MYELINATED A-FIBERS,SMALL UNMYELINATED C-FIBERS Dental Pain (Pulpitis) ◦ Pulpitis is an inflammation of the dental pulp that is usually caused by bacterial infections. ◦ It has two forms (reversible) pulpitis and (irreversible) pulpitis TYPES OF DENTAL PAIN 1-Sharp, stabbing localized pain (Occurs in cases of Reversible pulpitis) § Conducted by the A-delta fibers of the pulp; - As the A-fibers are myelinated axons and have a fast conduction speed , they transmit pain directly to the brain, and generate a sharp stabbing pain that is easily localized. - A-Fibers are activated by hydrodynamic stimuli, such as drilling, sweet foods, cold air.  2-Slow, diffuse, and referred pain (Occurs in cases of Irreversible pulpitis) § Conducted by the C- fibers of the pulp; - C fibers are unmyelinated and have a low conduction velocity. - located deeper than the myelinated fibers and cause slow, diffuse pain. The location of the C fibers in the core or central region of the pulp may explain the diffuse referred pain. - Clinical description of this type of pain is that it is it is a dull, vaguely located, aching pain that increases several seconds after a hot drink.  Sensory response in the pulp cannot differentiate between ◦ Heat, ◦ Touch, ◦ ◦ Pressure, Chemicals Pain This is because the pulp organs lack those types of receptors.  Type of nerve C-fibers A. fibers Myelination Unmyelinated axons Myelinated axons Conducting Low conduction Fast conduction speed speed speed Diameter Smaller diameter Larger diameter THE PLEXUS OF RASHCKOW: Pain Slow, diffuse, and Sharp, stabbing - LARGE MYELINATED A-FIBERS referred pain pain that is localized - SMALL UNMYELINATED C-FIBERS Stimulus Heat stimulus Hydrodynamic stimuli; drilling, sweets, cold air. Pulpitis Pulpitis* (irreversible) *Pulpitis (reversible) Location Center of the pulp Periphery of the pulp FUNCTION OF THE PULP Function of the pulp 1- Inductive 2- Formative 3-Nutritive 4-Protective 5- Defensive or reparative 1- Inductive: ◦ Dental papilla induces the enamel organ formation and also determines the morphology of the tooth. 2- Formative : Pulp organ produces dentin. Odontoblasts develop the organic matrix and function in its calcification. 3- Nutritive : ØThe pulp nourishes the dentin. ØNutrition is mediated through the odontoblasts and their processes. 4- Protective : ◦ The sensory nerves in the tooth respond with pain to all stimuli. ◦ Pain sensation is a useful alarm system of the pulp. 5- Defensive or reparative: 1. The pulp responds to irritation by producing reparative dentin. 2. These reparative reactions are an attempt to wall off the pulp from the source of irritation. a t ive r pa tin 3. The presence of macrophages, lymphocytes e R en D and leucocytes also aid in the process of repair of the pulp. AGE CHANGES OF THE PULP  The size of the pulp The cellular elements Age changes in the pulp The bl. vessels & n. Vitality 1- Size of the Pulp Continuous deposition of secondary dentin on pulp chamber especially floor of chamber leading to gradual reduction in size and obliteration of pulp chamber. (Pulp recession) So, the risk of pulp exposure during dental treatment is reduced by age. Apical foramen narrows by cementum deposition  ◦ By age, the cells of the pulp decrease: a) In number (especially UMC). b) In size. 2- Cellular c) In number of cytoplasmic organelles. Elements ◦ So, the reduction of pulp cell especially UMC reduces the regenerative and the reparative power of the pulp. 3-Vascular By age blood vessels show: 1. Decrease in number Change 2. Greater diameter of the vessel wall 3. Calcification around the bl.v walls  4-Neural Loss & degeneration of Change and nerve axon occurs by age, leading to reduction of pulp Vitality sensitivity.  Fibrosis Age changes in the pulp Pulp Calcification  ◦Increase in collagen fiber bundles which: 5- Fibrosis 1.Become arranged longitudinally in the radicular pulp. 2. And show random diffuse arrangement in coronal pulp. 6-Pulp Calcification According to structure: 1- Localized calcification: 2- Diifuse Calcification ◦ True Denticles ◦ False denticles 1-Localized Calcification ◦ True Denticles: ◦ True denticles are rare & small in size& found near the apical foramen. ◦ They consist of irregular dentin containing traces of dentinal tubules and few odontoblasts. ◦ Remnants of the epithelial root sheath invade the pulp tissues causing UMC of the pulp to form this irregular type of dentin. 1-Localized Calcification ◦ False Denticles: They are evidence of dystrophic calcification of the pulp tissue. They contain no dentinal tubules. They are formed of degenerated cells or areas of hemorrhage which act as a central nidus for calcification. Overdoses of vit. D, may favor the formation of numerous denticles. 1-Localized Attached Calcification ◦ False Denticles: ◦ Pulp stones are classified according to their location in relation to the walls of the pulp cavity into: 1. Free: in the pulp only. 2. Attached: Part in the pulp and part in dentin. Free 3. Interstitial or embedded: All in dentin, caused by the formation of secondary dentin around the attached denticle. ◦ They continue to increase in size and in certain cases they fill up the pulp chamber completely. 1-Localized Attached Calcification ◦ False Denticles: ◦ They are usually asymptomatic but: vIf pulp stones come close enough to a nerve bundle pain may be elicited. vThe close proximity of pulp stones to Free blood vessels may cause atrophy of it. 2-Diffuse Pulp Calcification ◦ Commonly occurs on top of hyaline degeneration in the root canal and not common in the pulp chamber. ◦ They are irregular calcific deposition in the pulp tissue following the course of blood vessels or collagenous bundle. ◦ Advancing age favors their development. Age Changes of the Pulp Size Cellularity Vascular changes Fibrosis Pulp stones (denticles) False Denticles True Denticles Diffuse Calcification THANK YOU