Dental avulsion
Dental avulsion is the complete displacement of a tooth from its socket in alveolar bone owing to trauma, such as can be caused by a fall, road traffic accident, assault, sports, or occupational injury. Typically, a tooth is held in place by the periodontal ligament, which becomes torn when the tooth is knocked out.
Avulsions of primary teeth are more common in young children as they learn to move independently and also from child abuse. Avulsed deciduous teeth should not be replanted. Deciduous teeth are not replanted because of the risk of damaging the developing permanent tooth germ. Pulp necrosis with draining fistula, crown discoloration and external root resorption are reported consequences of primary tooth replantation. Tooth dilaceration, impaction and deviation from proper eruption path have been reported to have occurred in permanent teeth as a result of reimplantation of primary teeth.
Avulsed permanent teeth however may be replanted, i.e., returned to the socket. Immediate replantation is considered ideal, but this may not be possible if the patient suffered other serious injuries. If properly preserved, teeth may be replanted up to one hour after avulsion. The success of delayed replantation depends on the survival of the cells remaining on the root surface. Storage in an environment similar to the tooth socket can protect these cells until replantation can be attempted.
Prevention
Contact sports carry a significant risk of dental injury, which can be reduced by wearing a mouthguard or helmet. Mouthguards are often less effective if not fitted properly to the teeth.Despite their wide availability, the use of mouthguards is relatively uncommon. Many people do not use them even in situations that carry a high risk of dental injury, or when their use is mandated. In addition, mouthguards may be dislodged from the wearer's mouth, leaving the teeth unprotected.
Certain occlusal characteristics, such as class II malocclusions with increased overjet, are associated with a higher risk of dental trauma. These conditions can be corrected by an orthodontist reducing risk of injury due to sports related activities.
Risk factors
- Post-normal occlusion
- An over-jet exceeding 4 mm
- Short upper lip
- Incompetent lips
- Mouth breathing
Management
Although dentists advise that the best treatment for an avulsed tooth is immediate replantation, for a variety of reasons this can be difficult for the layperson. The teeth are often covered with debris. This debris must be washed off with a physiological solution and not scrubbed. Often multiple teeth are knocked-out and the person will not know to which tooth socket an individual tooth belongs to. The injured victim may have other more serious injuries that require more immediate attention or injuries such as a severely lacerated bleeding lip or gum that prevent easy visualization of the socket. Pain may be severe, and the person may resist replantation of the teeth. People may, in light of infectious diseases, fear handling the teeth or touching the blood associated with them. If immediate replantation is not possible, the teeth should be placed in an appropriate storage solution and brought to a dentist who can then replant them. The dentist will clean the socket, wash the teeth if necessary, and replant them into their sockets. S/he will splint them to other unaffected teeth for a maximum of two weeks for teeth. Properly handled, even replantation of periodontally compromised permanent teeth in older patients under good maintenance have been reported, with splinting extending for over 4 weeks due to the reduced support structure for the root due to periodontal disease. Dental pulp of the avulsed teeth should be removed within 2 weeks of replantation and the teeth should receive root canal therapy.
In addition, as recommended in all cases of dental traumas, good oral hygiene with 0.12% chlorhexidine gluconate mouthwash, a soft and cold diet, and avoidance of smoking for several days may provide a favorable condition for periodontal ligaments regeneration.
Initial assessment
When a patient arrives at the dentist they should be seen immediately. If the tooth has not been placed in a suitable storage medium, the dentist will do this first. A thorough extra-oral and intra-oral examination should be performed. The clinician should consider the age of the patient, the history of the injury, status of tooth root apex and whether it is in line with clinical findings. It is advisable to check the patient's tetanus status. If there is concern about non-accidental injury, then child protection procedures should be followed.Re-implantation
Prior to the beginning of the procedure, a local anesthetic should be administered to both the palatal/lingual tissues to minimize discomfort. Gentle irrigation with a saline solution, should be performed as this removes any clots within the socket, which could prevent the proper re-positioning of the tooth into its original position. The tooth should always be handled via the enamel on the crown, not the root. Wash the root surface with saline, be careful not to scrub the root surface, as this may crush the delicate cells. Any stubborn debris can be removed by agitating it in the storage medium or by rinsing under a stream of saline.Stabilize the tooth for 2 weeks using a passive and flexible wire mouth rinse twice a day for 2 weeks.
Biologic basis for success of replantation following avulsion
Every tooth is connected to its surrounding bone by the periodontal ligament. The tooth receives its nourishment through this ligament. When a tooth is knocked out, this ligament is stretched and torn. If the torn periodontal ligament can be kept alive, the tooth can be replanted, and the ligament will reattach, and the tooth can be maintained in its socket. The torn ligament that stays on the socket wall, since it remains connected to the bone and blood supply, is naturally kept alive. However, the ligament cells that remain on the tooth root lose their blood and nutrition supply and must be artificially maintained. They must be protected from two potentially destructive processes: cell crushing and loss of normal cell metabolism. All treatment between the time of the accident and the ultimate replantation must be focused on preventing these two possibilities.Prevention of cell crushing
When teeth are knocked out, they end up on an artificial surface: the floor, the ground or material such as carpeting. If the surface is hard, the tooth root cells will be traumatized. Since the cells remaining on the tooth root are very delicate, additional trauma to the PDL cells must be avoided so as to avoid more cell crushing. This damage can occur while picking the tooth up and/or during transportation to the dentist.When a tooth is picked up, it should always be grasped by the enamel on the crown. Finger pressure on the tooth root cells will cause cell crushing. Any attempt to clean off any debris should be avoided. Debris should always be washed off gently with, at the very least, a physiologic saline. Even with the use of a physiologic saline, the "scrubbing" of the tooth root to remove debris must be avoided. When placed in a physiologic solution, the tooth should be gently agitated to permit the cleansing of the tooth root. At the same time that this agitation occurs, the bumping of the tooth root against a hard surface such as glass, plastic or even cardboard must also be avoided. For the same reasons, the method in which the knocked-out teeth are transported must be carefully selected. Placing the knocked-out teeth by transporting in tissues and handkerchiefs can be damaging and transporting them in glass or cardboard containers can also be potentially damaging to the cells. In addition to the potential damage that the hard surface can cause, glass containers have the added possibility of breakage or leakage of the physiologic storage fluid. If the glass container does not have a tightly fitting top, then during the transportation, the physiologic storage solution can spill out and the teeth can fall, once again, on the floor and, at the same time, be out of a physiologic environment.
Maintenance of normal cell metabolism
Normally metabolizing tooth root cells have an internal cell pressure of 280–300 mOs and a pH of 7.2. When there is an uninterrupted blood supply, all of the metabolites and glucose that the cells require are provided. When the tooth is knocked out, this normal blood supply is cut off and within 15 minutes most of the stored metabolites have been depleted and the cells will begin to die. Within one to two hours, enough cells will die that rejection of the tooth by the body at a later time is the usual outcome. The method by which the body rejects the replanted tooth is a process called "replacement root resorption". During this process, the tooth root cells become necrotic and will activate the immunologic mechanism of the body to attempt to remove this necrotic layer and literally eats away the tooth root. This is called "root resorption". It is a slow, but non-painful, process that is sometimes not observed by x-rays for years. Once this process starts, it is irreversible, and the tooth will eventually fall out. In growing children, this can cause bone development problems because the replacement resorption attaches the tooth firmly to the jawbone and stops normal tooth eruption and impedes normal jaw growth.Research has shown that the critical factor for reduction of the death of the tooth root cells and the subsequent root replacement resorption following reimplantation of knocked-out teeth is maintenance of normal cell physiology and metabolism of the cells left on the tooth root while the tooth is out of the socket. In order to maintain this normalcy, the environment in which the teeth are stored must supply the optimum internal cell pressure, cell nutrients and pH.