Advances in treatment of avulsed tooth

[Anonymous]

The treatment of avulsed teeth has changed rapidly in the last several years. The previously reported poor success rates of reimplanted avulsed teeth (4% to 50%) can be improved to over 90% with a modified approach to treatment.

Until recently, all avulsed teeth were treated in the same way, which involved reimplantation of the tooth immediately or as soon as possible after the avulsion. This approach was followed regardless of how much time had passed since the avulsion accident and was attempted even if the avulsed tooth was dehydrated and the periodontal ligament (PDL) cells were no longer viable. This philosophy became pervasive, and practitioners did not recommend any other treatment. This occurred despite evidence in the literature that did not support this approach.

Each patient who has suffered an avulsed tooth arrives at the dentist’s office with a specific set of circumstances. The history is evaluated, a diagnosis is made, then treatment is instituted. The treatment of avulsed teeth should, therefore, be dependent upon the specific clinical conditions that present to the dentist. These clinical factors are the following: the physiologic status of the PDL, the stage of root development, and the length of time since avulsion (extraoral time). The availability and use of a specialized storage and preservation medium, a cushioning and retrieval system, topical antibiotics, and enamel matrix protein promoters can increase reimplantation success.

BIOLOGIC RATIONALE FOR TREATMENT RECOMMENDATIONS

Status of the Development of the Root Apex

In certain instances, it is possible for the pulp tissue in immature avulsed teeth to completely revascularize. Researchers differ as to which factor is most influential regarding the incidence of revascularization. Important parameters include the width of the apical foramen, duration of time the tooth is outside the socket, and storage conditions. However, there is agreement that bacterial contamination can prevent revascularization of the pulp. Soaking avulsed teeth in a 1-mg/20-mL solution of doxycycline for 5 minutes prior to reimplantation has been shown to decrease root resorption and—of greater significance—to increase the frequency of pulpal revascularization.

Physiologic Status of the PDL Cells
The status of PDL cells remaining on the root surface of an avulsed tooth determines the development of replacement root resorption.If the PDL cells are healthy, a new attachment to the surrounding alveolar bone is possible. If the PDL cells are metabolically stressed or damaged physically, the root cementum will experience necrosis. A new PDL will not form, and the surrounding alveolar bone will view the root surface as foreign and resorption will occur. In order for optimum physiologic conditions to be maintained, the PDL cells on the avulsed tooth require nutrients and the proper pH. In order for proper structure and physiology to be maintained, the cells must be in an appropriate osmotic environment and must be protected from physical damage.

Pre-reimplantation Stage
Table 1. Categories of Avulsed Teeth1

Category 1. Mature apex, < 15 minutes out of mouth.
Category 2. Mature apex, 15 minutes to 6 hours in physiologic solution.
Category 3. Mature apex, 15 minutes to 1 hour in nonphysiologic solution.
Category 4. Mature apex, > 1 hour dry storage.
Category 5. Immature apex, < 15 minutes out of mouth.
Category 6. Immature apex, 15 minutes to 6 hours in physiologic solution.
Category 7. Immature apex, 15 minutes to 1 hour in nonphysiologic solution.
Category 8. Immature apex, > 1 hour dry storage.

Table 2. Treatment for Each Category of Avulsed Teeth1
Category 1. Mature apex, < 15 minutes out of mouth.
(1) Rinse tooth with physiologic solution to remove debris from root surface.
(2) Flush socket with sterile water or saline.
(3) Reimplant tooth in the socket.

Category 2. Mature apex, 15 minutes to 6 hours in physiologic solution.
(1) Place in HBSS for 30 minutes.
(2) Flush socket with sterile water or saline.
(3) Reimplant tooth in the socket.
(4) Splint tooth in a functional position.

Category 3. Mature apex, 15 minutes to 1 hour in nonphysiologic storage.
(1) Place in HBSS for 30 minutes.
(2) Flush socket with sterile water or saline.
(3) Reimplant tooth in the socket.
(4) Splint tooth in a functional position.

Category 4. Mature apex, > 1 hour dry storage.
(1) Remove remnants of the periodontal ligament by soaking in sodium hypochlorite
for 10 to 15 minutes.
(2) Instrument the root canal with tooth out of mouth.
(3) Soak the tooth in a 2% stannous fluoride solution for 5 minutes.
(4) Obturate the root canal with gutta-percha.
(5) Coat the tooth root with Emdogain, and place Emdogain in the socket.
(6) Reimplant the tooth in the socket.
(7) Splint tooth in a functional position.

Category 5. Immature apex, < 15 minutes out of mouth.
(1) Soak the tooth in a doxycycline solution for 5 minutes.
(2) Reimplant the tooth in the socket.
(3) Splint tooth in a functional position.
(4) Check tooth for vitality and apex closure every month.

Category 6. Immature apex, 15 minutes to 6 hours in physiologic solution.
(1) Soak in a doxycycline solution for 5 minutes.
(2) Flush socket with sterile water or saline.
(3) Reimplant tooth in the socket.
(4) Splint tooth in a functional position.

Category 7. Immature apex, 15 minutes to 1 hour in nonphysiologic solution.
(1) Place in HBSS for 30 minutes.
(2) Soak in a doxycycline solution for 5 minutes.
(3) Flush socket with sterile water or saline.
(4) Reimplant tooth in the socket.
(5) Splint tooth in a functional position.

Category 8. Immature apex, > 1 hour dry storage.
(1) Remove remnants of the periodontal ligament by soaking in sodium hypochlorite for 10 to 15 minutes.
(2) Instrument the root canal with tooth out of the mouth.
(3) Soak the tooth in a 2% stannous fluoride solution for 5 minutes.
(4) Obturate the root canal with gutta-percha.
(5) Coat the tooth root with Emdogain, and place Emdogain in the socket.
(6) Reimplant the tooth in the socket.
(7) Splint tooth in a functional position.

Patients with avulsed teeth can be categorized into one of 8 categories. Only patients with avulsed teeth in category 1 benefit from immediate reimplantation. Patients in the other 7 categories benefit from prereimplantation conditioning of affected teeth.

The clinician reimplanting the tooth must be concerned with maintaining the PDL cells in their original state or returning the cells to as healthy a condition as possible. By so doing, the remaining PDL cells will be able to differentiate and reestablish a new PDL. The PDL cells that remain on the root following the avulsion do not have a blood supply and begin to deplete their stored metabolites. In order to maintain optimal cell metabolism, the depleted metabolites must be replaced within 1 hour after avulsion.1 After this time, the untreated PDL cells will undergo necrosis, the cementum will be lost, and root resorption will occur following reimplantation.

Since teeth are rarely reimplanted within this time frame, biologic storage of the avulsed teeth and protection of the PDL cells from physical damage are of paramount importance. Many methods of storage have been proposed. Except for the pH-balanced cell culture media, all of these methods either damage the PDL cells (water and saliva), or at best are of limited benefit (milk). Milk has been shown to be a compatible short-term storage medium if the avulsed teeth are placed in milk within 15 to 20 minutes following avulsion.However, milk only prevents cell death; it does not restore normal cell morphology or the ability of these cells to differentiate and undergo mitosis. More significantly, the studies of milk as a storage medium have been performed under ideal conditions. In most of these studies, teeth were extracted, immediately placed in milk, and then left for variable periods of time. The conclusions regarding milk as a storage medium were thus based on conditions that did not mimic actual clinical conditions.

Teeth that have been outside the mouth for 15 minutes or more should not be immediately reimplanted but rather soaked in a pH-balanced cell-reconstituting medium such as HBSS for 30 minutes and then reimplanted.Once the teeth have been placed in HBSS, they can remain in that solution for up to 24 hours. Some studies have suggested that 70% of PDL cells can remain viable for as long as 4 days in HBSS.

Even if avulsed teeth are stored in saline or milk from the moment of the avulsion accident, the teeth should still be soaked in HBSS for 30 minutes prior to reimplantation. PDL cells that are stored in milk remain vital but lack the capacity for mitosis and reformation of the PDL.

The status of PDL cells remaining on the root surface of an avulsed tooth determines the development of replacement root resorption. If the PDL cells are healthy, a new attachment to the surrounding alveolar bone is possible. If the PDL cells are metabolically stressed or damaged physically, the root cementum will experience necrosis. A new PDL will not form, and the surrounding alveolar bone will view the root surface as foreign and resorption will occur. In order for optimum physiologic conditions to be maintained, the PDL cells on the avulsed tooth require nutrients and the proper pH. In order for proper structure and physiology to be maintained, the cells must be in an appropriate osmotic environment and must be protected from physical damage.

        

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