Apical healing
1-Introduction:
The periapex constitutes a functional unit where all the components are linked by fibers and vessels, and where the BLACK space (nutrient center) ensures the metabolism of the hard tissues that surround it: the cementum on one side and the alveolar bone on the other side.
However, this space has a strong potential for regeneration that endodontic treatment, through root canal obturation, should stimulate, leading to apical healing.
Three successive phases:
– Disappearance of inflammation
– Formation of fibrous connective tissue repair (bone, cementum, desmodontal)
– Tissue regeneration.
Healing : Complex physiological repair phenomenon, generally very progressive and slow.
• Repair : this is the filling of the lesion with a tissue different from the original tissue, i.e. healing tissue (Grossman).
• Healing or regeneration : this is the return of tissues to their previous state after treatment.
2. The periapex:
2.1. Anatomy :
It is a crossroads region that contains the alveolar-dental ligament and connective tissue rich in cells.
This region is richly vascularized by the dental artery and its anastomoses with the interdental arteries. It is a region in perpetual remodeling and when the tissues composing it are the site of an aggression, they can resorb.
According to (KUTTLER), the apical region is formed by the joining of two inverted hourglass-shaped cones = KUTTLER cones, one dentine at its summit at the cemento-dentine junction, the other purely cementine is inverted with respect to the first, its summit is located at the cemento-dentine junction at the point of narrowing of the dentine cone and its base is at the apical foramen.
Apical healing
2-2-Histology:
The periapex is made up of a set of histologically different elements:
Apical cementum: The cementum covering the apical dentin serves as an anchor for the Shrapey ligament collagen fibers. It is an avascular and mineralized tissue that is remodeled by continuous cemental apposition depending on age. Cemental apposition predominates in the apical region.
Acellular cementum: the collagen fibers from the neighboring connective tissue are included in the cementum layer, thus constituting the SHARPEY fibers, thus giving the acellular or fibrillar cementum. It constitutes 2/3 of the cementum tissue.
Cellular cementum: cementoblasts will deposit on the acellular cementum to produce cellular cementum.
Apical desmodontium: The desmodontal connective tissue is a multifunctional tissue characterized by its strong capacity for remodeling and adaptation, and a real potential for regeneration linked to its own cellular component. It is crossed from one side to the other by the oriented bundles of collagen fibers that serve as anchors to the tooth.
The cell population of the desmodont varies according to its central or parietal location:
• The diffuse and abundant population of fibroblasts is responsible for the homeostasis of collagen fibers and ground substance proteins during physiological remodeling and during healing of periapical lesions.
• The permanent set of defense cells (macrophages, mast cells, lymphocytes) increase during inflammatory processes.
• Cementoblasts and osteoblasts, lining the cementum and bone walls respectively, are responsible for mineral neoformations during physiological cementum and alveolar remodeling as well as during repair processes.
• Epithelial cells, residues of Hertwig’s sheath, form Malassez epithelial clusters or debris, involved in the pathogenesis of apical cysts.
Alveolar bone: The alveolar bone wall is a structure perforated by vessels and nerves, a cribliform lamina allowing the connection of the periodontium to the medullary spaces of the cancellous bone of the maxilla and mandible. The alveolar bone provides anchorage for Sharpey’s fibers. After eruption, an adaptation mechanism preserves this bone anchorage as well as the integrity of the periodontium, a source of progenitor cells allowing tissue renewal.
3-Repair potential of the periapex:
After pulp eviction, the dentinogenetic function of the latter is cancelled; but there remain at the apex, living elements such as cementum, bone which are the supports of the periapical repair.
Any endodontic infection causes an inflammatory reaction at the apical level which will result in a decrease in synthetic activity and an increase in osteoclastic and cementoclastic phenomena. Once the preliminary inflammatory phase is controlled by the defense cells, and endodontic treatment is well established, biological repair can begin.
3-1-Bone repair:
Newly formed bone replaces the fibrous tissue. The inflammatory process induces the differentiation and proliferation of osteoclasts on the alveolar wall adjacent to the inflamed site, which then begins to resorb. Root resorptions are only radiologically detectable from a certain degree of root destruction.
When the stimuli disappear, new osteoblasts in front secrete an organic matrix at the origin of new bone tissue. The latter carry out dental anchoring in the form of mineralized SHARPEY fibers. The osteoblasts surrounded by mineralized matrix become osteocytes and constitute a set of reserve cells which participate in bone metabolism.
Injured or resorbed bone is replaced by remodeled bone rather than a fibrous scar. To initiate this regenerative process, three events are required: recruitment, modulation, and osteoconduction. Recruitment involves the migration of osteoprogenitor cells to the repair site. Modulation involves the activation of osteoprogenitor cells and their differentiation into active osteoblasts. Osteoconduction involves the formation of a three-dimensional matrix on which osteoblasts deposit new bone.
After resective bone surgery: osteoclastic activity lasts 2 to 3 weeks, then a phase of osteoblastic reconstruction will follow with a peak of activity 3 to 4 weeks later and bone apposition completes healing 6 months later.
3-2-Cement repair:
The gaps are filled and lined with a thin layer of cementum which allows the reattachment of the newly formed desmodontal fibers .
Cementoblasts provide cellular repair and successive layers of newly formed cementum cover the root and the canal filling material at the level of the foramen provided that there is no apical overhang.
It is less radiopaque, therefore less mineralized than the tissue surrounding it.
3-3-Desmodontal repair:
At the ligament level, the changes observed are in the direction of an increase in differentiation and cellular activity, especially for a functional tooth compared to a tooth that is not. Fibroblasts ensure the remodeling of desmodontal fibers. Indeed, their main function is the synthesis and secretion of collagen precursors which then undergo their maturation.
The reconstruction of the desmodont will indicate healing when the regular periradicular radiolucent space, which represents the healthy desmodont, reappears on the radiograph.
4-The dynamics of healing after treatment of the lesion:
Apical lesion healing peaks during the first year.
85% of teeth that will heal show signs of healing during this first year (reduction in the size of the lesion). At 2 years, most of the lesions are healed and the others continue to heal over 4 to 5 years.
5-Healing criteria:
Clinical criteria:
– absence of symptoms
– absence of fistula or swelling
– non-painful percussion
Radiological criteria
– regular, non-expanded ligament.
– absence of apical image.
– continuity of the lamina dura.
6-Factors influencing healing:
Generals:
– Age, nutrition, general health, hormonal, vitamin and organic disorders, etc.
– Local:
– persistent infection
– hemorrhage
– tissue laceration
– presence of foreign bodies (instrument, gutta, etc.)
– presence of accessory canals.
7-CONCLUSION:
No regeneration will occur until the irritants have been removed from the root canal system; and until this root canal system has been isolated from the rest of the body by endodontic sealing.
Apical healing
Sensitive teeth react to hot, cold or sweet.
Sensitive teeth react to hot, cold or sweet.
Ceramic crowns perfectly imitate the appearance of natural teeth.
Regular dental care reduces the risk of serious problems.
Impacted teeth can cause pain and require intervention.
Antiseptic mouthwashes help reduce plaque.
Fractured teeth can be repaired with modern techniques.
A balanced diet promotes healthy teeth and gums.