PULP CONTENTS INTRODUCTION DEVELOPMENT ANATOMY STRUCTURAL FEATURES FUNCTIONS PRIMARY AND PERMANENT PULP ORGANS REGRESSIVE CHANGES CLINICAL CONSIDERATIONS
INTRODUCTION Every individual has a heart study, reliable yet as every lover knows, oh so fragile. So, too does every tooth have a heart. Amazingly dependable, highly functional and yet as every dentist knows oh so fragile. Encased in the rigid, unyielding loosening of tooth enamel, dentin and dentin, this freshly mass of complex connective tissue presents a unique niche of specialization. The only soft part of the tooth its loving entity is the pulp. Being in a low compliance environment, the pulp has a fabulous defense arsenal to help it perform its function increasingly. However, it is equally in a pressure cooker situation and can very easily succemd to environmental stimuli. It is this variability that has led to the saying some pulps die if you look crossly at them, this wont if you chop than with an axe. So let us look at the fascinating tissue complete with an electrical supply and the throbbing heart to see what makes it tick.
First the definition: According to Cohen â€“ By definition, the pulp is a soft tissue of mesenchymal origin residing within the pulp chamber and root anal of teeth. Now, to begin with lets explore how the baby is born. DEVELOPMENT: The dental pulp has it genesis in about the 6th week of 10 life during initiation of tooth development. The tooth pulp is initially called the dental papilla. This tissue is designated as pulp only after dentin forms around it. The dental papilla control early tooth formation. In the earliest stages of tooth development it is the area of the proliferating future papilla that causes the oral epithelium to invaginate and from the enamel organs. These organs then enlarge to enclose the dental papilla in their control portions. The dental papilla also controls whether the forming enamel organ is to be an incisor or a molar. The development of the dental pulp (at the incisor) begins at the eighth week of embryonic life. The cell density of the dental papilla is great as a
result of proliferation of the cells within it. The young dental papilla is highly visualized and a well organized network of vessels appears by the time dentin formation begins. Capillaries crowd among the odontoblasts during this period of active dentinogenesis. The cells of the dental papilla appear as undifferentiated mesnechymal cells. Gradually these cells differentiate into stellate shaped fibroblasts. After the inner and outer enamel organ cells into ameloblasts, the odontoblasts then differentiate from the peripheral cells of the dental papilla production begins. As this occurs, the tissue is no longer called dental papilla but is now designated the pulp organ. Few large myelinated nerves are found in the pulp until the dentin of the crown is well advanced. At that time nerves reach the odontogenic zones in the pulp horns. The sympathetic nerves, however, follow the blood vessels into the dental papilla as the pulp begins to organize. Anatomy: General features: The dental pulp occupies the center of end of tooth and consists of soft connective tissue. Every person, normally has a total of 52 pulp organs. 32 in permanent teeth and 20 in primary teeth with the shape confirming to that of the respective tooth. The total volume of all permanent teeth pulp organs is 0.38 cc and the mean value of a single adult human pulp is 0.02 cc.
Each pulp organ is composed of a coronal pulp located centrally in the crowns of teeth and a root or radicular pulp. Coronal pulp: In young individuals, the coronal pulp resembles the shape of the outer surface of the crown. It has 6 surfaces â€“ occlusal, mesial, distal, buccal, lingual and the floor. It has pulp horns which are protrusions that extend into the cusps of each tooth. The number of horns hence, depends on the cuspal number. The cervical region constricts as does the contour of the crown and at this zone the coronal pulp joins the radicular pulp. RADICULAR PULP: The pulp extending from the cervical region of the crown to the root apex is radicular pulp. Single in anterior and multiple is posteriors, they are not always straight and vary in size, shape and number. The radicular portions are continuous with the periapical connective tissues through the apical foramen or foramina. The shape is tubular and as tooth matures, radicular pulp narrows. The apical pulp canal is made smaller also because of apical cementum deposition. In its apical 3 rd multiple accessory canals form the apical delta which may complicate endodontic therapy.
APICAL FORAMEN: The small openings at the root through which enter and exit vascular, lymphatic and nerve elements is the apical foramen. It may be composed of dentin surfaced by cementum or cementum alone. They vary in diameter, location, shape and number. The average diameter for mandibular teeth is about 0.3m and 0.4m for maxillary teeth. They are large and centrally locted in developing teeth and become smaller and eccentric in position on maturation. The largest diameter foramen are in the palatal root of maxillary molars and distal root of mandibular molars. Foramen may be located at the very end or anatomic apex but are usually located slightly more occlusally. They covered with anatomic apex only in 17-46% and are located at average 0.5-0.7m away from the apex). There might be a single foramina or root canal branching to form 2 foramen changes in the morphology, location and size of the foramen by periapical deposition of cementum can be induced by physiologic changes such as root canal therapy, occlusal foramina and mesial drift. ACCESSORY CANALS: Seen anywhere along the root, through particularly numerous in the apical third, these lead from the radicular pulp laterally through root dentin to the periodontal tissue. During root sheath formation, a break develops in the continuity of a sheath producing a small gap and dentinogenesis does not occur opposite 6
this defect resulting in formation of an accessory canal. It may also occur where the developing root encounters a blood vessel. The following OHP gives the gross description of shape of pulps of maxillary and mandibular teeth and variation in size of pulp organs of permanent teeth. Maxillary: CI LI C FP SP M Mandibular CI LI C FP SP M
STRUCTURAL FEATURES / HISTOLOGY When the pulp is examined microscopically four distinct zones can be distinguished. 1. The odontogenic zone composed of odontoblasts (at the periphery). 2. The cell free zone or Weil’s zone. 3. The cell rich zone. 4. The central region or zone containing large nerves and blood vessels. 1. ODONTOBLASTIC ZONE: Consisting of odontoblasts, the second most prominent cell in the pulp, this zone is adjacent to the predentin.odontoblasts are 5.7µ in diameter, 20-45µ in length. The cell bodies are columnar with large oval media basally. Immediately adjacent are rough surfaced endoplasmic reticulum and Golgi apparatus. Junctional complexes are present. The process of the cell, the odontoblastic process extends to varying lengths into the dentin. This is the formative zone of the pulp and its junction with dentin on all fronts.
2. CELL FREE ZONE: Also called zone of weil, a 40Âľ thick relatively free of cells area underlying the odontoblast layer is the characteristic. The area is not present in all teeth and need not circumscribe the entire pulp and usually of variable thickness. In pulps actively producing dentin, cellfree zone is absent. The components are ground substance with fibres. Also, the area is not totally devoid of cells. Fibroblasts macrophages, pericysts and mesenchymal cells are present. Importantly, the plexus of capillaries and nerve plexus of Raschow are present. The unmyelinated nerve plexus of Raschow is involved in the neural sensation of the pulp. The capillary plexus is involved in the nutrition of odontoblasts and cells of the zone. The ground substance is involved in metabolic exchange of the cells and limits spread of infection. 3. CELL RICH ZONE: The cell rich zone is located central to the cell free zone. Its main components are ground substance, fibroblasts with their product of collagen fibres, undifferentiated mesenchymal cells and macrophages. Found both coronally and in radicular pulp, it is much less obvious in the latter specially apically.
4. PULP CORE or PULP PROPER: The central connective tissue mass from the cell rich zone inward is known as the pulp core or pulp proper. It contains blood vessels and nerves embedded in the pulp matrix together with fibroblasts. In young pulps, the cell population is greater while in older pulps fibre density is higher. The neurovascular bundles enter / exit this core through the apical foramen and accessory channels. STRUCTURAL COMPONENTS: The constituents of this entity include ground substance, fibres, connective tissue cells such as fibroblasts, mesenchymal cells, pericysts, histiocytes, fixed macrophages, lyphoid wandering cells, mast cells, blood and lymph vessels and nerves. Firstly: Ground Substances: The intercellular amorphous ground substance is the main constituent of the dental pulp resembling that of any other loose connective tissue. It is dense and gel like in nature varying in appearance from finely granular to fibrillar. It is composed mainly of:
1. Acid mucopolysacchairdes. 2. Protein polysaccharide compounds i.e. glycosaminoglycans and proteoglycans. During early development chondritis A and B and hyaluronic acid have been demonstrated. Also glycopeptide and glycosaminolipids are present. The proteoglycans are hyaluronic acid, chondroitin sulfate, dermatis sulfate and heparin sulfate. Major glycoprotein is fibronectin along with laminin and tenascin. Its functions include: 1. Lend support to the cells of the pulp. 2. Serves as a means for transport of nutrient from the blood vessels to cells as well as for transport of metabolites from cells to blood vessels. 3. Serves as a barrier against the spread of bacteria and limits spread of infection because of its consistency. 4. Regulates osmotic pressure. Age and disease may change the composition and function of the ground substance.
Next we come to the fibres of the pulp: FIBRES: Mainly consisting of collagenous fibres, also present are reticular, oxytalan and elastic fibres. These undergo change throughout life in both quantity and variety. Principally collagen fibres of type I and type III in an appropriate ratio of 55.45 are found, remains constant throughout. The collagen fibres exhibit typical 64m cross striations and range in length from 10 to 100nm or more. They are argyrophilic in young pulps. On root completion bundles of fibres increase and are termed diffuse or bundle collagen depends on appearance can be demonstrated by mason errichone or mallos tripe connective tissue stain. Fibre bundles have their greatest concentration in the apical portion, a fact of clinical significance is that during pulpectomy engaging the pulp with a barbed broach in the region of the apex ensure better intact tissue extirpation. Oxytalan fibres are observed in the developing dental papilla elastic fibres are found on maturation, basically incorporated into the walls of afferent vessels. They are therefore confined to the walls of arterioles. After this lets look at the cellular components of the dental pulp. First comes the odontoblasts which have been discussed in the odontogenic zone of the pulp.
Next come the fibroblasts: The pulp fibroblast is the predominant and most numerous cell type. Particularly numerous in the coronal portion of the pulp especially in the cell rich zone. They function in collagen fibre formation throughout the life of the tooth pulp, mainly type I and III collagen as well as proteoglycans and GAG. Also, ability to phagocytose and dyst collagen entrusts them with the collagen burnover in the pulp. They have typical stellate shape and extensive processes that contact and are joined by intercellular junctions to the processes of other fibroblasts. In young pulps the cells divide and are active in protein synthesis. In older pulp they appear rounded or spindle shaped with short processes. They are then known as fibrocytes. In the course of development the cellular elements decreases whereas fibrous components predominate. Interestingly it has been remarked that fibroblasts of pulp like Peter pan, â€œnewer grow upâ€? for these cells seen to remain is relatively undifferentiated modality compared to fibroblast of most other connective tissues. Importantly, they have a dual function with followup for both synthesis and degradation.
UNDIFFERENTIATED MESENCHYMAL CELLS: These represent the pool from which connective tissue cells of the pulp are derived. They are the primary cells of the very young pulp but decrease on root completion and maturation. Appearing larger than fibroblast, they are Polyhedral in shape with peripheral processes and large oral staining nuclein. They are found in pulp vessels, in the cell rich zone and scattered throughout central pulp. They are the totipotent cells which depending on the stimulus transform into odontoblasts, fibroblasts or macrophages. A reduction in their number in older pulps reduces the negative potential of the pulp. Next are the defense or immunocompetent cells: Firstly macrophages â€“ or histiocytes â€“ macrophages are the monocytes that have left the blood stream, entered the tissues and differentiated into various subpopulations. It is an irregularly shaped cell its short blunt processes with small rounded, darky stain nuclei and exhibits granular cytoplasm. Dyes like trypan blue can disclose their presence especially in inflammation. The distinguishing feature is aggregates of vesicles or phagosomes, they are associated with small blood vessels and capillaries. Because of their mobility and phagocytic activity, they act as scavengers removing extravasated RBC s dead cells and foreign bodies from tissue.
Ingested material is destroyed by the lysosomal enzymes. In inflammation, they remove bacteria and interact with other inflammatory cells. Also they participate in immune reactions and also produce various soluble factors like interleukin-1 TNF etc. DENDRITIC CELLS: These are the accessory cells of the immune system. They are nonphagocytic and participate in pulpal immuno surveillance. These together with macrophages contribute 8% of total pulpal cell population and dendritic cells exceed macrophages in the ratio of 4:1. Similar cells are found in the epidermis and mucous membranes where they are called Langerhanâ€™s cells. Primarily found in lymphoid tissues, they are widely distributed in connective tissue including pulp. They are termed antigen presenting cells and are characterized by dendritic cytoplasmic processes. They engulf (Cohen) proteins antigen and plays central role in induction of T cell dependent immunity. Next, both lymphocytes and eosinophils are found in normal pulp increasing markedly in inflammation. T8 (suppressant) lymphocytes are predominant B lymphocytes are severe in normal pulp. Mast cells are widely distributed in connective tissue and are seen along vessels in pulp especially inflamed pulp. Having a round nucleus and
contains many granules, they have a dermatic role in inflammatory reactions containing heparin and histamine among others. Lastly are the plasma cells seen during pulpal inflammation. The cell has a cart wheel appearance and function in the production of antibodies. BLOOD VESSELS AND VASCULAR SUPPLY: The pulp organ is extensively vascularized. The blood vessels of the pulp and periodontium arise from the inferior or superior alveolar artery and also drain by the same veins in both the mandibular and maxillary regions. Both apical and accessory canal connections exist which are of clinical significance because of potential of spread of infection from pulp to periodontium and vice versa. Small arteries and arterioles enter the apical canal and persue a direct route to coronal pulp having diameter of 100Âľ or less. Along their cause they give off numerous branches is the radicular pulp that pass peripherally to form a plexus in the odontogenic region. Pulpal blood flow is more rapid than in most areas of the body which may be attributed to the pulpal pressure while is among the higher of body tissues. The flow of blood in arterioles is 0.3 to 1m/s in vesicles approximately 0.15m/s and 0.08m/s in capillaries. The pulpal interestial pressure is about 5-8mm of Hg.
The vessels have 3 layers namely: a) The first is the Tunica Intima: Consisting of squamous or cuboid endothelium surrounded by closely associated basal lamina this layer lives the lumen. b) The Tunica Media is the second layer approximately 5µ thick, consisting of 1-3 layers of smooth muscles. A basal lamina separates the media from the intima. Occasionally, the endothelial cell wall is in contact with the muscle cells forming a myoendothelial junction. The 3rd and outer layer is the Tunica Adventitia: It is made up of few collagen fibres forming a loose net work around layer arteries and is more conspicuous in older pulp. The layer arterioles give way to arterioles with diameter of 20-30µ commonly seen throughout coronal pulp. Terminal arterioles of 10-15µ appear peripherally is pulp. A fibroblast or pericyte may lie on the surface of these vessels. Pericysts are capillary associated fibroblasts. The smaller arterioles are also called precapillaries ranging from 8-12µm size. These are confluent with capillaries. The true capillary is a simple endothelial tube of 8-10µ diameter. The nuclei of these cells may be tabulated and have cytoplasmic projections
into labial surface. The terminal network is the coronal pulp appears perpendicular to the main branches. The vascular network passes among odontoblasts and underlies them as well. Fenestrated capillaries are believed to be involved in rapid transport of metabolites during active odontoblastic activity. Also present are meta arterioles and precapillaries. The capillary blood flow coronally is nearly twice radicular flow and greater in pulp horns. From the capillaries blood flow into postcapillary venules and then into larger venules. This blood is drained by a system of venules that are comparison venules of arterioles. Veins and venules that are larger than arteries appear in the central region of root pulp measuring 100-150Âľm in diameter with less regular walls. They have luminar walls in relation to lumen size, flatter endothelial cells and their cytoplasm does not project into the lumen. The tunica media consists of a single layer or 2 of this smooth muscle cells that wrap around the endothelial cells and appear discontinuous or absent in small venules. The basement membranes are thinner and the adventitia is lacking or appears as fibroblasts and fibres confirm with pulp tissue. Another important feature are the AVAs or arteriovenous anastomoses. These vessels directly connect arterioles with venules and thus shunt or bypass the capillary network. Present both coronally and radicular, more
particular in the latter. These have an important role to play in regulation of pulpal circulation. The most vascularized area is the periphery at the odontogenic layer. Also pulpal blood flow is substantially lower than a major visceral organs indicating that the respiratory rate of pulp cells is relatively low. Next are the lymphatics: The presence of lymph vessels remains a controversial topic, elucidated upon by some and questioned by others. Lymph capillaries are described as endothelium triad tubes that join thin walled lymph venules or veins in the central pulp. Lymph vessels arise as small, blind, this walled vessels in the coronal region of the pulp and pass apically through the middle and radicular regions of the pulp to exit via 1 or 2 larger vessels through the apical foramen. Larger vessels have an irregular shaped lumen composed of endothelial cells surrounded by an incomplete layer of pericysts or smooth muscle cells. They are also characterized by the absence of red blood cells and presence of lymphocytes. The cytoplasm of the endothelial cells contains WEIBEL-PALADE granules containing a hemostatic agent the Von Willebrand factor. Lymph vessel drain pulp and periodontal ligament have a common outlet. 19
For anterior teeth they pass to the submental lymph nodes posterior teeth drain into the submandibular and deep cervical lymph nodes. Now lets look at the nerve supply of pulpal innervation: First the nerves of the pulp: The abundant nerve supply follows the distribution of the blood vessels. The sensory mechanisms of the pulp is composed of: a) Sensory afferent â€“ conducts impulses from pulp to brain which are interpreted as pain regardless of stimulus. b) Autonomic afferent â€“ conducts impulses from central system to the smooth muscles of the arterial vessels to regulate blood flow. The sensory system appears to be well suited for signaling potential damage to the tooth. In addition to sensory nerves, sympathetic fibres from the superior cervical ganglion regulate blood flow and are thought to be involved in regulation of dentinogenesis. Nerve fibres also extend into dentinal tubules through only about 10-20% of coronal dentin contain nerve endings.
The major groups are: A group of myelinated nerve fibres –approx. 20%. C group of fibres – approx. 80%. The A fibres include both Aβ and Aδ (delta) fibres. The Aβ are more sensitive than Aδ. approx 90% of the A fibres are A delta. Principal characteristic: A delta fibres (Aδ) Myelinated, diameter of 2-5µ, conduction velocity of 6-30m/s, larger diameter, impulses interpreted as sharp pricks pain and distributed in odontoblastic and subodontoblastic zones, associated with dentinal pain. C-fibres; Unmyelinated, diameter of 0.3-1.2µ, velocity of 0.4-2m/s distributed throughout pulp tissue and conduct throbbing and aching pain associated with pulp tissue damage. The nerve trunk is composed of myelinated A delta fibres in periphery and unmyelinated C fibres in the center.
The sensory pathways is – Nerve impulses Nerve trunk Max. or mand nerve trigeminal nerve pons thalamus cortex perceived or interpreted as pain. Efferent motor pathway Sympathetic fibres from superior cervical ganglion enter via apical foramen in outer layer of arterioles (tunica adventitia) and terminate in the muscles of tunica media. Then lets see the overall nerve supply: Nerve supply parallel’s vascular supply: the majority of fibres are nonmyelinated, may later become myelinated. Also sympathetic nerves having terminate on larger vessels regulate blood flow. Thick nerve bundles enter the apical foramen and proceed to the coronal area where the fibres separate and radiate peripherally to the odontogenic zone. The number of fibres is the bundles very from 150-1200 sizes range from 5-13µ. The large myelinated fibres mediate the sensation of pain that may be caused by external stimuli. The peripheral axons form a network of nerve adjacent to the cell rich zone known as the parietal layer of nerves or plexus of Raschkow. It becomes prominent when root formation is complete. Myelinated fibres upto 5µ in diameter as well as delicate non-myelinated fibres less than 1600nm 22
constitute the plexus. There is profile branching of the fibres in the plexus producing a tremendous overlap of receptor fields. Full development of this plexus does not occur until the final stages of root formation. Finally come the NERVE ENDINGS OR TERMINALS: Nerve axons from the parietal zone pass through the cell rich and cell free zones and either terminate among or pass between the odontoblasts to terminate adjacent to the odontoblast processes at the pulp predentin border or in the dentinal tubules. Nerve terminals consisting of round or oval enlargements of the terminal filaments contain microvesicles, small dark granular bodies and ribochondria. These terminates are very close to the odontoblast plasma membrane separated only by 20Âľ. Most of these endings are believed to be sensory receptors with some sympathetic endings too. Nerve axons found among the odontoblasts and in the cell free and cell rich zones are non myelinated but are enclosed in a Schwan cell covering. More nerve fibres and endings are found in the pulp horns than in other peripheral areas of the coronal pulp. 4 types of terminal configuration are seen: 1. Simple marginal pulpal nerve fibres seen from subodontoblastic nerve plexus to odontoblastic layer. 23
2. Simple predental nerve fibres run straight or spirally through a dentinal tubule. 3. Complex predental nerve fibres reach the predentin and undergo a terminal ramification with multiple branches and endings. 4. Dentinal nerve fibres seen without transverse course along dentinal tubules into dentin. Of
neurotransmitters. Substances such as substance P, 5-Hydroxyforamine, vasoactive intestinal peptide, somatostain, prostaglandin as well as acetyl choline and norepinephrine, calciton gave related peptide, neuropeptide, Y, neurokinin A, etc, have been found throughout pulp. Various stimuli elicit their release once evoked they affect vascular tone and modify excitability of nerve endings. In addition, they promote wound healing. Another unique feature is that sensory responses in the pulp cannot differentiate between heat, touch, pressure or chemical, because of absence of specific receptors. All environmental stimuli elicit pain as a response. FUNCTIONS OF PULP: 1. INDUCTIVE: The first role of the pulp anlage is to induce oral epithelial differentiation into dental lamina and enamel organ formation. Also induces developing enamel organ to become a 24
particular type of tooth. The interaction between the epithelium of the tooth germ and the ectomesenchyme in the dental papilla during the bud, cap and bell stages of tooth germ maturation are reciprocally inductive. 2. FORMATIVE AND MORPHOLOGIC FUNCTIONS: The pulp organ cells produce the dentin that surrounds and protects the pulp. Odontoblasts develop the organic matrix and function in its calcification. The cells also determine the form acquired by the coronal pulp chamber as well as volume of the pulp. 3. NUTRITIVE: dentin being avascular, depends on the underlying tissues for its blood supply and lymph drainage. The pulp nourishes the dentin through the odontoblasts and their processes and by means of the blood vascular system of the pulp. 4. SENSORY: Myelinated and nonmyelinated nerves are found in the pulp. All the stimuli received are interpreted as pain. Thus chemical, pressures, thermal and other stimuli evoke pain. 5. PROTECTIVE: The sensory nerves respond with pain to all stimuli. These initiate reflexes that control circulation in the pulp. This sympathetic function is a reflex, providing stimulation to
visceral motor fibres terminating on the muscles of the blood vessels. 6. DEFENSIVE OR REPARATIVE: The pulp is an organ with remarkable reparative abilities. It responds to insults whether mechanical, thermal, chemical or bacterial by producing reparative dentin and tubular sclerosis. Also acute stimulation may provoke inflammatory reactions and cardinal symptoms are set in motion including pain. Various cells of the pulp aid in the repair process. The rigid dentinal wall and the unyield, enclosure can lead to partial or complete vascular collapse and necrosis of the pulp. However, if the inflammation is not too severe, the pulp will heal via its excellent regenerative properties. PRIMARY AND PERMANENT PULP ORGANS: PRIMARY: they function for a shorter period than permanent pulp organs. Average length of function is 8.3 years which can be divided into 3 time periods: 1) Pulp organ growth: Takes place during the time the crown and root are developing. 2) Pulp maturation: The period after the root is completed until root resorption begins. 26
3) Pulp regression: Period from beginning of root resorption until exfoliation. The 3 periods are not of equal lengths: Tooth eruption to root completion is about 1 year. Root completion to begins root loss is 3 yrs, 9 month. Pulp regression is 3 yrs, 6 month. Maximum life of primary pulp is approx 9.6 yrs. PERMANENT PULP ORGANS: during crown formation, pulp of primary and permanent teeth are morphologically nearly identical. In permanent teeth this process requires about 5 yrs. Primary teeth however never attain the extent of permanent teeth neural development although both are highly vascularized. The remaining architecture is similar. The periods of development for permanent pulps are longer crown completion averages 5 yrs, 5 months. Crown completion to eruption is 3 yrs, 6 months. Eruption to root completion is 3 yrs, 11 months. Thus, the pulp undergo development for about 12 yrs, 4 months in contrast to 4 yrs, 2 months for primary teeth. Also permanent root take time as long to reach complete (7 yrs 5 month) as compared to primary pulp (3 yrs, 3 months).
The period of pulp aging is much accelerated in primary teeth about 7 yrs, 5 months. Aging of permanent teeth requires much of the adult life span. Finally, for both primary and permanent teeth, the maxillary arches require slightly longer to complete each process than mandibular. AGE AND REGRESSIVE CHANGES IN THE PULP: 1. DIMENSIONAL CHANGES: The most conspicuous age change is the reduction in volume of the pulp due to continous deposition of secondary dentin and reparative dentin in response to stimuli. This dimunition is called atrophy. 2. CELL CHANGES: Cells become fever in number and also characterized by decrease in size and number of cytoplasmic organelles. 3. FIBROSIS: In the aging pulp accumulation of tooth diffuse fibrillar componenets as well as bundles of collagen fibres appear. The increase in fibers is gradual and generalized throughout the organ. Any external trauma causes a localized fibrosis or scaling effect. The increase in collagen fibres may be more apparent than actual, attributable to decrease in pulp size, making the fibres occupy less space and look more concentrated. It has even been theorized that pulpal fibrosis does not increase as a result of age.
4. VASCULAR AND MISCELLANEOUS : Plaques may appear in pulpal vessels. In other cases, the outer diameter of vessel walls become greater as collagen fibres increase. Also calcification are found in blood vessels especially near the apical foramen. Also there is a loss and a degeneration of myelinated and unmyelinated axons. Another important age change are the calcification of the dental pulp. So now we come to the : PULP STONES OR DENTICLES: Pulp stones are nodular, calcified masses appearing in the coronal or root portions of the pulp. They develop in teeth quite normal in other aspect and can be seen in functional as well as embedded unerupted teeth. Their etiology is still unclear and have not been associated with any abnormalities of the pulp yet. CLASSIFICATION: According to their structure: 1. True denticles. 2. False denticles. 3. Diffuse calcifications.
TRUE DENTICLES: their structure is similar to dentine. They are rare and are usually seen close to the apical foramen. They exhibit dental tubuli containing odontoblasts processes. A theory put forth states that the development of true denticles is caused by the inclusion of remnants of the epithelial root sheath within the pulp which induce the pulpal cell to differentiate into odontoblasts and form pulp stones. FALSE DENTICLES: These do not exhibit dentinal tubules but appear instead as concentric layers of calcified tissue and can appear with a bundle of collagen fibres or in a pulp force of collage accumulations. Some arise around vessels, having remnants of necrotic and calcified cells centrally. Calcification of thrombi in blood vessels called phleboliths may also serve as mid for false denticles. All denticles begin as small nodules but increase in size by incremental growth or their surface. The surrounding pulp tissue may appear quite normal. Pulp stones may eventually fill substantial parts of the pulp chamber. DIFFUSE CALCIFICATIONS: They appear as irregular calcific deposits in the pulp tissue usually following collagenous fibre bundles or blood vessels. Sometimes they 30
develop into larger masses but usually persist as fine calcified spicules. Pulp appears normal. They are usually found in the root canal whereas denticles are more frequent in the coronal pulp. Pulp stones are also classified according to their location in relation to the surrounding dentinal wall: 1. Free denticles â€“ Entirely surrounded by pulp tissue. 2. Attached denticles â€“ partly fused with dentin. 3. Embedded denticles â€“ entirely surrounded by dentin. All are believed to be formed free is the pulp, later getting attached or embedded. The incidence of pulp stones is more prevalent than roentgenographically visible. Their incidence and size increases with age. Approx. -
66% of teeth in person of 10-30 yrs of age.
80% of teeth in persons of 30-50 yrs of age.
And 90% of teeth in persons over 50 yrs of age contain calcifications of some type.
Also included under calcification causes CALCIFIC METAMORPHOSIS luxation of teeth as a result of trauma may result in calcific metamorphosis, a condition that can in months of yrs lead to partial or complete radiographic obliteration of the pulp chamber due to excessive deposition of mineralized tissue resembling cementum or occasionally bone. Clinically the crowns appear a yellowish hue and usually occurs in teeth with incomplete root formation subjected to traumatic insult. Lastly we come to the CLINICAL CONSIDERATIONS: 1. During operative procedures, the shape of the pulp chamber and its extensions into cusps, the pulpal horns is important to remember. The wide pulp chamber of young individuals makes deep cavity preparation hazardous. In some developmental disturbances, pulpal horns project high into the cusps and unanticipated exposure can occur. A radiograph helps determine the size of pulp chamber and extent of pulpal horns. 2. During opening of pulp chamber for therapy, the morphology and its variations must be kept in mind with advances age, pulp chamber becomes smaller and location of canals is more difficult. In such cases largest canal is located first in posterior i.e. distal in mandibular and palatal in maxillary to avoid perforation. In
anteriors pulp chamber may be filled with secondary dentin making canal location difficult. Also pulp stones lyin at openings or other locations render root canal therapy difficult and cumbersome. 3. Apical foramen, the land mark for endodontic procedures varies in shape and location when narrowed by cementum, it is more readily located, if it is at the side of the apex, misjudgement of canal length and filling occurs. Also, in younger pulps with trauma, incomplete development of apex may necessitate a pulpotomy or apexification procedure. 4. Accessory canals are a very interesting and varying problem. Rarely visible on radiographs and difficult or rather impossible to reach, they remain untreated. The majority do not affect RCT success. However, when accessory canals are located near coronal part of root or in bifurcation, a deep periodontal pocket may cause pulpal inflammation. Thus periodontal disease can have a profound effect on pulp integrity and vice versa. 5. VITAL PULP THERAPY: Exposed pulps are no longer lost pulps. Present into defense and reparative mechanisms of pulp have revolutionized pulp preservation. Non infected or minimally infected pulps if capped properly can form dentinal bridges and 33
retain vitality. Primary tooth pulp capping is remarkably successful. Various materials like Ca(OH)2, dentin bonding agents and MTA are used. 6. All operative procedures and materials cause an initial response in the pulp dependent on the severity of insult. Even slight stimulus causes inflammatory cell infiltration. Severe reaction result in hyperaemia compounds like Ca(OH)2 induce reparative dentin formation. Also lesser the dentinal depth or closer the restoration, greater is the response. 7. Dehydration, being harmful to the pulp, should be avoided while using potentially harmful chemicals cavity lines should be employed. 8. A vital pulp is essential to good dentition. Although modern endodontists can prolong tooth longevity, non-vital teeth become brittle and are subjecte to fractures. Thus, any precaution should be taken to preserve vitality of pulp. 9. Internal resorption, usually initiated due to trauma, is usually asymptomatic and recognized on radiographs as a resorptive defect and should be treated by endodontic therapy before perforation.
10. Caries can elicit varied responses from the pulp from mild inflammation to necrosis to stimulation. Thus various pathologies like hyperalgesia or reversible pulpitis to irreversible pulpitis, periapical pathologies or hyperplastic pulpitis are seen and must be handled appropriately. 11. Vitality of pulp is one of the hottest topics of interest and research. From the thermal pulp tests involving heat and cold to the vitalometer involving electrical stimuli to A delta fibres all record neural vitality of pulp not vascular which is the true indicator. Latest techniques like laser Doppler flowmetry and pulse oximetry are slowly making inroads as means of measuring pulpal vitality and determining therapeutic options.
CONCLUSION: It is often in the past that we find the future. Thus a thorough and complete assimilation of the myriad and fantastic database on the dynamics of the pulp and a knowledge of various elucidations past, present and future will go a long way in ensuring that we, as dental physicians, provide the highest level of technical and scientific accuracy and artistic flair in the holistic well being of the tooth organ and in turn fulfill the aspiration of those individuals who place in us their unwavering trust - our patients.