MEANS OF DEFENSE OF THE DENTAL ORGAN
I.INTRODUCTION
The dental organ is an entity composed of multiple tissues, each of which has a particular structure and physiology that allows them to ensure their own defenses and consequently the defense of the entire dental organ.
II. DEFENSE MECHANISMS
2.1. Odontology:
2.1.1. Enamel
Physiologically, enamel has no means of defense or regeneration; it constitutes a capital of hardness that must be preserved against carious attack.
2.1.2 Cementum
Structurally, cementum resembles bone because it has a neighboring calcification, but it differs from it from a functional point of view, because it is neither vascularized nor innervated, nor interested in lymphatic drainage.
It is a protective tissue that serves as an anchor for Sharpey’s fibers, it is deposited continuously and remodels the root morphology, in compensation for eruption, in reaction to mesial drift and physiological dental movements.
2.1.3 The pulp-dentin complex
1.Dentin
Faced with an attack from the oral cavity, the pulp seeks to preserve its vitality by synthesizing scar tissue called tertiary dentin.
The latter includes 02 types of dentin which differ by the nature of the pulp response observed, the structure of the dentin formed and the type of cells involved: These are the reaction dentin and the reparative dentin.
1.1. REACTION DENTIN
It is produced by odontoblasts that have differentiated during the development of the tooth germ. It is generally found under slowly developing dentin caries. It comprises 02 topographically distinct parts:
Sclerotic reaction dentin:
It is observed at the periphery of carious lesions, at this level, the dentinal tubules are partially or completely blocked, either by the precipitation of phosphocalcic salts in the form of apatite, or by centripetal secretion of the peri-tubular dentin, thus reducing the permeability of the dentin with respect to aggressors.
Peripulpal reaction dentin:
Peripulpal dentin is formed at the dentin-pulp interface by odontoblasts under the effect of increased enzymatic activity (alkaline phosphatase and ATPase) which allow the release of phosphates and the production of energy necessary for rapid mineralization of the newly deposited dentin framework.
1.2. Reparative dentin
It is produced following the necrosis of odontoblasts, by replacement cells (odontoblasts) from:
either from the subodontoblastic region of Hhöl which will divide, then migrate in contact with the zone of necrosis and differentiate into replacement odontoblasts.
Either they come from undifferentiated pulp fibroblasts. These cells would proliferate, then migrate towards the pulp periphery towards the dentin before differentiating into odontoblasts
THE 3 LINES OF DEFENSE OF DENTIN
2. The pulp
2.1. Pulp inflammation
Bacteria are the cause of pulp inflammation or infection; this phenomenon is governed by physio-pathological mechanisms identical to any inflammation of the connective tissue.
Within the pulp tissue, this reaction can be moderate or severe, depending on the intensity of the aggressive agent; it begins insidiously, spreads slowly in a rather chronic manner, possibly punctuated by acute attacks.
a.1 Onset of inflammation:
When a cavity reaches the dentin, the pulp reacts in response by the diffusion of soluble irritants, these substances include toxins, enzymes, organic acids resulting in tissue destruction
The reaction varies, depending on the caries process and the speed of progression.
a.2 Inflammation itself:
a .2. 1 Vascular phase
Which aims to neutralize the aggressive agent characterized:
Vasodilation and increased vascular permeability
Release of molecules by mast cells (Histamine…
Activation of plasma proteins (bradykinin, complement)
Secretion of lipid mediators (prostaglandins …
a .2. 2. Proliferative response
Leukocyte margination
Diapedesis: passage of the endothelial wall by leukocytes which begins with cellular adhesion by adhesion molecules
a .2 .3. Chemical mediators of inflammation :
Various mediators are released:
-vasoactive amines, arachidonic acid metabolites, neuropeptides, cytokinins and prostaglandins are responsible for pain.
The purpose of local vasodilation is to increase blood circulation in order to evacuate dead cells and toxins (detersion), and to provide the elements necessary for healing, in particular white blood cells (lymphocytes) to fight the aggressor. This local swelling of the blood vessels causes redness and a sensation of heat, as well as an effusion of water from the blood plasma by osmosis towards the tissues, causing edema.
In summary: Mechanisms of inflammation
– The inflammatory process has 3 main phases:
*Vascular: vasculo-exudative (inflammatory exudation)
*Cellular: Combat and Elimination
*Tissue: repair
B/Pulp atrophy:
It is a premature aging of the pulp by a traumatic process, which alters the reparative process, leads to the transformation of the internal anatomy of the tooth, to the reduction of the volume of the pulp chamber and the root canal by intrapulpal mineralization.
C/Degeneration:
These are calcifications that appear in the teeth of elderly people due to the deposition of canalicular dentin.
D/Pulp necrosis:
The pulp is housed in a cavity with inextensible walls; during inflammation, intrapulpal pressure occurs due to compression of the venules, which causes congestion then tissue hypoxia and finally necrosis.
2.2 The periodontium
2.2.1 The gum
a. Turnover
The gingival epithelium is constantly renewed, the keratin layer on the surface becomes thicker depending on the amount of friction during chewing.
b. Inflammation
Like all connective tissue, inflammation is a response to an aggression of moderate or significant intensity, passing through the different phases mentioned above.
Its defense role is ensured by the immune phagocytic cells existing within the gingival chorion
2.2.2 The periodontal ligament
It has a defensive role: thanks to the existence of defense cells such as macrophages and histiocytes, the desmodont can resist inflammatory and infectious attacks.
MEANS OF DEFENSE OF THE DENTAL ORGAN
Misplaced wisdom teeth can damage adjacent teeth.
Ceramic dental crowns provide a natural-looking result.
Receding gums can expose tooth roots.
Clear aligners are a discreet alternative to braces.
Composite fillings are less visible than amalgam.
Interdental brushes prevent gum problems.
A diet rich in calcium strengthens teeth and bones.