Lecture 4. Аnatomy and physiology of pulp in children. Pulpitis. Classification, etiology, pathogenesis, differential diagnostics in children.

Date: 2015-10-07; view: 565.

Pulpitis of the temporary and permanent teeth.

The dental pulp (pulpae vitae) as a formation of the connective tissue is a component of the integral organism, all the changes of which (age changes, physiological, pathological) have influence onto it.

The tooth pulp is situated in the tooth cavity (cavitas dentis). Topographically we determine the crown pulp and root pulp. In general the shape of the pulp corresponds to the dental cavity contours as well as contours of root canals. Some part of the pulp in projection of cutting edge of the incisors and tubercles of the masticatory teeth is situated close to the occlusal surface and forms pulp horns (cornu pulpae). In teeth with many roots we may sometimes observe additional canals in the area of the floor of dental cavity (bifurcations, trifurcations).

The pulp develops from the dental papilla (papilla dentalis) and it contains puffy connective tissue of embryonal type in which we may define three layers:

peripheral( odontoblasts), medial which includes two parts- a layer, poor in cells, and a layer of cell accumulation; and the central one.

The peripheral pulp layer contains odontoblasts which are situated like a palisade, these are the cylindrical cells. They are highly differentiated cells which have metabolic, synthesizing and secreting functions. The odontoblasts form the dentine and perform metabolic processes in it.

Medial layer. This is the layer which is poor in cells( Weil's layer), in its crown part it contains subodontoblastic nervous plexuses; the medial and apical parts of the crown pulp don't contain this layer.

The layer of accumulated cells is formed with fibroblasts and non-differentiated mesenchyma cells which are able to change into odontoblasts and odontoblast-like cells.

The central pulp layer is totally formed with fibroblasts, histiocytes and lymphoid cells which provide for the protective and germinative function.

The pulp has well developed circulatory system the function of which is transport. The vessels penetrate into the pulp through the orifice of the tooth apex as well as through the lateral and additional canals. A control of blood supply is provided via the sympathetic nerve fibers ( which cause noradrenaline excretion, which leads to vessel contraction) and the parasympathetic ones (excretion of acetylcholine which provides for the vessel dilation).

The presence of collateral blood circulation, providing for backward blood flow) in the pulp stipulates for the inflammation process elimination.

The lymphatic system of the pulp is represented with lymphatic fissures and vessels.

The pulp innervation is performed by means of еру thick nerve trunks situated in the central layer of the root pulp. When approaching the crown pulp, the nerve trunks branch towards the peripheral layer. In the layer which is poor for the cells, the nerve fibers lose their myeline layer and make subodontoblastic nerve plexus (Rashkov's plexus), then they surround the odontoblasts as circular nerve endings. Some fibrillas are situated between the odontoblasts up to the pulp-dentine border. A part of them penetrates the predentine. High pulp sensitivity for pain is caused by a large number of nerve receptors.

The temporary tooth pulp.

During the immature root period the tooth cavity and root canals of the temporary teeth are larger than those of the permanent teeth. The crown pulp directly passes into the root one, it doesn't have deltaic branching of the root canal and additional canals.

The pulp of the temporary teeth during the immature root period is characterized by the presence of small amount of plasmatic cells which have protective function. In this period the pulp is adequately supplied with the nerve elements and vessels. There haven't been determined any difference between the morphological structure of the crown and root pulp. An odontoblast layer is formed with two-three layers of cells. During this period the pulp is characterized by the great amount of cells of active mesenchyma, medial substance and precolagen fibers. Such morphological structure provides for high biological potential of the pulp, increases metabolic processes intensity which determines the protective properties of the pulp.

During the mature root period the pulp is able to accumulate secondary dentine only in response to stimulating actions.

A period of root reabsorption is characterized by regressive changes in the pulp: decreased number of cellular elements until their complete atrophy, vacuole degeneration of the odontoblasts. In the majority of cases there occurs partial or complete small-looped reticular atrophy. We may observe thickening and calcification of vessel walls, congestive hyperemia, sometimes hemorrhages appear. In the nerve apparatus of the pulp there appear degenerative changes ranging from the bulb-like swelling to fragmentation and decay of the nerve fibers. There increases the amount of medial amorphous substance and collagen fibers. These histological changes in the pulp cause decrease of its pain sensitivity and this is clinically manifested. On the initial stage of root resorption the number of odontoblast rows decreases, there are two-three of them. The cells decrease in their size and the nuclei shrink. During this period the pulp isn't able to resist the pathological stimuli, it has less intensive reaction onto the thermal and chemical stimuli, it is relatively quickly able to necrotize asystematically and this may manifest only during clinical examination.

The pulp of the permanent tooth with immature roots. The pulp of the erupted tooth is large and the crown pulp directly passes into the root one. After termination of root maturation the pulp stays quite large for some time period, then it gradually decreases in size as a result of secondary dentine formation; during secondary dentine formation there occur changes in number, shape and size of root canals, deltaic branchings in the apical part and additional canals are formed.

The pulp of the permanent erupted tooth is a connective tissue of embryonal type, and it is rich for the cellular elements. Odontoblasts fit closely one to each other, they are situated in 5-12 rows, the majority of them is observed in the areas of horns and equator. The layer, which is rich in cells, is well expressed. They are represented with non-differentiated circular and stellate cells of fibroblast row. The differentiation of the crown pulp into the root one occurs in combination with the growth and formation of the root, it starts on the level of dental equator. In the central pulp layer there prevail the reticular fibers and a little number of collagen fibers. The odontoblasts are situated in 4-5 rows in the crown pulp part. A large number of vessels and medial amorphous substance provides for the intensive metabolic processes and high biopotential of the pulp. In the growth area the pulp directly borders with the periapical tissue.

Pulpitis of the temporary tooth.

The main etiological agent that causes pulpitis in both children and adults is represented with microorganisms which penetrate into the pulp from the carious cavity. These are predominantly aerobic microorganisms or both aerobic and anaerobic microorganisms. Also, the pulpitis may develop under the action of traumatic, chemical and temperature stimuli.

Classification of pulpitis after the specialists of Kiev Medical Institute( O. Yavorska, L. Urbanovich):

I. Acute pulpitis(pulpitis acuta).

1) Hyperemia of the pulp( hyperaemia pulpae).

2) Acute localized pulpitis( pulpitis acuta serosa circumscripta).

3) Acute diffuse pulpitis( pulpitis acuta serosa diffusa).

4) Acute purulent pulpitis( pulpitis acuta purulenta).

5) Acute traumatic pulpitis(pulpitis acuta traumatica).

a) Occasionally injured pulp area(during caries treatment).

b) Opening of the pulp caused by tooth crown fracture.

II. Chronic pulpitis( pulpitis chronica).

1) Chronic fibrous pulpitis ( pulpitis chronica simplex seu fibrosa).

2) Chronic hypertrophic pulpitis( pulpitis chronica hypertrophica).

3) Chronic gangrenous pulpitis( pulpitis chronica gangraenosa).

4) Concrement pulpitis( pulpitis concrementosa).

III. Pulpitis complicated by periodontitis( acute, chronic or exacerbated).

It is worth mentioning that in the temporary teeth such forms of acute inflammation as pulp hyperemia, acute serous local pulpitis, are extremely short-lasting and can't be diagnosed clinically. This is why the pulpitis classification may be used for the temporary teeth in a little changed version, which reflects those pulpitis forms which may occur clinically.

Differential diagnostics of pulpitis of the temporary teeth

The development of pulpitis in the temporary teeth is closely related to the tooth development stage reflecting the morphological and functional peculiarities of the pulp and its ability to resist the stimulants.

The stage of immature root of the temporary tooth. The predominating forms here are chronic fibrous pulpitis which develops as a primary-chronic process, asymptomatically, and an exacerbation of this pulpitis. The exacerbation may be accompanied with an expressed reaction from the periodontium-perifocal periodontitis.

The period of completely mature root of the temporary tooth. We may diagnose only chronic forms of pulpitis, often complicated with a focal periodontitis. The development of the pulpitis is almost asymptomatic, which may be explained by the involute changes of pulp structure. The prevailing form here is the chronic fibrous pulpitis. Chronic gangrenous pulpitis is diagnosed more often here than during the other periods.

Complication of the chronic pulpitis may develop on any stage. It appears in children after being ill with viral or infectious diseases which are accompanied with weakening of body's defensive mechanisms.

Development of pulpitis in the permanent teeth in children is closely related to the tooth development stage.

On the stage of immature root the prevailing in clinical picture forms are the chronic fibrous pulpitis, its exacerbation and acute traumatic pulpitis (occasional pulp denudation during preparation of the carious cavity).

Acute forms of pulpitis of infectious origin are rarely diagnosed in teeth with immature roots. This may be related to both morphological and functional immaturity of the pulp, absent conditions for the pressure increase in the tooth tissues- during this period the tooth has wide apical orifices of roots and wide dentine canals, which provides for exudate outflow.

We can also diagnose both acute and chronic forms of pulp inflammation on stage of completely mature roots of the permanent teeth.

In this period the prevailing forms are chronic pulp inflammations, this is the chronic fibrous pulpitis and exacerbation of chronic fibrous pulpitis.

The character of inflammation in the pulp depends on the force and duration of action of etiological factors as well as on the condition of general somatic health of the child.