Written by Paul Krasner, DDS Friday, 30 April 2004 19:00
The treatment of avulsed teeth has undergone many changes in the last 10 years. In 1995, a new approach to treatment of avulsed teeth was proposed by Krasner and Rankow.1 This concept was based on (1) the manner in which the teeth were stored prior to reimplantation, (2) the length of time since avulsion, and (3) the extent of development of the root apex. They proposed 10 treatment categories, which were subsequently reduced to 8 categories.2 Each of these categories is based on the condition of the avulsed tooth when the patient arrives at the dentist's office. One important concept was that if the avulsed tooth was stored under optimum conditions (eg, with use of the Save-A-Tooth system), the success rate of reimplantation would increase to more than 90%.3
The Save-A-Tooth system protects the avulsed tooth from being damaged during transport and subsequent removal of the avulsed tooth from the transport container. The storage solution helps to maintain the normal metabolism of the cells of the periodontal ligament (PDL cells) for 24 hours.2 The transport and storage media (Hank's Balanced Salt Solution) have been shown to be optimal for storage of avulsed teeth,4-6 and are recommended by Trope7,8 as well as the American Association of Endodontists.9
The use of the Save-A-Tooth system addresses only the first of 3 phases of treatment of the avulsed tooth. There are 2 other phases of treatment following the initial reimplantation: endodontic treatment and post reimplantation care. This article will address the endodontic treatment phase.
ENDODONTIC TREATMENT PHASE IN THE MANAGEMENT OF AVULSED TEETH
Biologic Basis for Endodontic Treatment of Avulsed Teeth
When a tooth is avulsed, the pulpal blood vessels are severed. In a tooth with a closed apex, there is no chance for revascularization. In this case, the pulp will begin to experience cellular necrosis within 1 hour. Because of numerous portals of entry for bacteria into the pulp space, the pulp will soon become infected.
As the infection progresses, the pulp will become severely inflamed. The pulp space will become filled with a combination of acute and chronic inflammatory cells that are present in the pulp or enter the pulp space from remaining blood vessels. This pathologic process begins to extend from the pulp space through the dentinal tubules and lateral canals and into the space between the alveolar bone and reimplanted tooth. This was the space that was occupied by the PDL prior to the avulsion. This stimulates the formation of "clastic" cells that begin to resorb the cementum. This type of resorption has been described by Andreasen as "inflammatory root resorption"10 (see diagram). Significant inflammatory external root resorption can occur very quickly. If not halted, the resorptive process can penetrate into the pulpal space. If this occurs, the prognosis for long-term retention is poor.
The cause for this type of root resorption is, therefore, an infected and degenerating pulp. This process can be prevented if the pulp is removed within 7 to 10 days of the reimplantation.7,8 Although this pathogenic process should indicate immediate removal of the pulp at the time of the reimplantation, this is not the case. This is because the entire ligament and tooth socket are inflamed. Under the best of circumstances, the chemo-mechanical removal of the pulp causes increased inflammation in the periapical space. In addition, since both calcium hydroxide and Ledermix (the recommended interappointment medicaments) induce inflammation, filling the root canal space with either agent at the time of reimplantation will cause additional inflammation that may result in increased resorption. Therefore, the pulp should not be instrumented and the space should not be filled until at least 1 week after reimplantation.7-9
There is an additional reason for not removing the pulp at the time of reimplantation. The most important factor in success following reimplantation of the avulsed tooth is maintaining the PDL cells in the most optimal morphologic and physiologic condition that is possible.1,6-8,11 Delaying the reimplantation in order to accomplish the root canal treatment increases the time the tooth is outside its socket and can lead to a reduction in the ultimate success rate. In addition, the PDL cells that remain on the root surface can be physically damaged while the clinician holds the avulsed tooth during endodontic instrumentation and obturation.1,2,7,8 This also can increase the possibility of replacement resorption.
There are 3 factors that influence the approach to endodontic treatment of an avulsed tooth: (1) the length of time that has elapsed between the time of reimplantation and the time that the endodontic treatment is initiated; (2) the degree of apical root formation; and (3) the length of time the avulsed tooth was outside of the mouth prior to reimplantation.
Further, the greater the time that has elapsed between the reimplantation and the start of endodontic treatment, the greater the degree of infection that will exist in the pulp system. Since teeth with an open apex have the capacity for revascularization of the pulp following reimplantation, in certain cases endodontic treatment is delayed to determine if revascularization will occur. If the avulsed tooth has been outside of the mouth for more than 60 minutes (in nonbiologic storage or a nonphysiologic storage medium), endodontic treatment should be performed prior to reimplantation. (Biologic storage medium is considered to be any fluid that keeps the tooth in a normal physiologic and metabolic condition. As mentioned, the best medium for this is a pH-balanced fluid such as Hank's Balanced Salt Solution. For short periods of time, milk and sterile saline are also considered biologic. For a full discussion of appropriate storage media, refer to reference 1.)
Based on these 3 factors, there are 4 categories to be considered.
•Endodontic treatment of reimplanted avulsed teeth:
Category 1—closed apex, less than 2 weeks after reimplantation, no periapical radiolucency.
Category 2—closed apex, greater than 2 weeks after reimplantation, with or without apical radiolucency present.
Category 3—open apex, biologic storage prior to reimplantation.
•Endodontic treatment of nonreimplanted avulsed teeth:
Category 4—closed or open apex, nonbiologic storage prior to reimplantation.
The treatment for avulsed teeth that have not been stored in a biologic solution (Category 4) has been discussed.1,2 For these teeth, endodontic treatment can be performed extraorally, the teeth properly conditioned, then reimplanted.
RATIONALE FOR ENDODONTIC TREATMENT OF AVULSED TEETH
Category 1—Closed Apex, Less Than 2 Weeks After Reimplantation, No Periapical Radiolucency
If the avulsed tooth has a closed apex, less than 2 weeks have elapsed between the reimplantation and endodontic treatment, and there is no periapical radiolucency present, then the pulp space will not be infected unless infection occurred prior to avulsion. In this case, after the pulp has been chemo-mechanically removed, calcium hydroxide should be placed for 7 to 10 days.7,8 After this time, the pulp system can be obturated.
Calcium hydroxide is used for the following reasons: (1) it is an effective antibacterial agent; (2) it favorably influences the local environment at the resorption site, thus promoting healing; (3) it induces a more alkaline pH in the dentin at the resorption site, which slows the action of the resorptive cells; and (4) it promotes hard-tissue formation.
Another intracanal medicament that has been used is Ledermix.7,8 It is an antibiotic-corticosteroid paste that is effective because it inhibits the action of resorptive cells without damaging the PDL. At the present time, however, Ledermix is not available in the United States.
Category 1—Clinical Procedure
(1) Prepare access in the normal fashion.
(2) Chemo-mechanically instrument the canal.
(3) Place calcium hydroxide in canal system for 7 to 10 days.
(4) Remove calcium hydroxide with either hand instruments or rotary instruments. Instrument to one size larger than the previous visit.
(5) Irrigate and dry the canal.
(7) Seal access with composite resin.
(8) Follow up every 3 months for a year, then yearly.
Category 2—Closed Apex, Greater Than 2 Weeks After Reimplantation, With or Without an Apical Radiolucency Present
If the reimplanted tooth has an apical radiolucency and/or more than 2 weeks have elapsed following reimplantation, it is assumed that the root canal is completely infected, thus requiring an extended period of disinfection. This is best achieved by intracanal calcium hydroxide treatment. Calcium hydroxide is placed in the canal after the instrumentation is complete, and the tooth is followed with radiographs every 3 months, watching for resorption.7,8 The medicament should be changed no more frequently than every 3 months because calcium hydroxide can cause necrosis of new PDL cells.7,8
When the apical radiolucency appears to have resolved, and the periodontal ligament and lamina dura are observed around the root, the root canal can be obturated.
Category 2—Clinical Procedure
(1) Prepare access in the normal fashion.
(2) Chemo-mechanically instrument the canal.
(3) Place calcium hydroxide in the canal system for 3 months.
(4) Radiograph to observe if new PDL space is forming along the root and at apex.
(5) If no sign of PDL formation, remove calcium hydroxide with either hand instruments or rotary instruments. Instrument to one size larger than the previous visit and place a new mix of calcium hydroxide.
(6) Continue radiographs and replace calcium hydroxide every 3 months until PDL is observed.
(7) When new PDL is observed, remove calcium hydroxide.
(8) Irrigate and dry the canal.
(10) Seal access with composite resin.
(11) Follow up every 3 months for a year, then yearly.
Category 3—Open Apex, Biologic Storage Prior to Reimplantation
Since avulsed teeth with open apices that have been outside the mouth for less than 60 minutes have the potential for revascularization of the pulp, endodontic treatment should be postponed until there are definite signs of pulpal necrosis. These signs are periradicular inflammation (radiolucency); external root resorption; no return of sensation with pulp testing, eg, use of cold, heat, or Doppler flowometry. (The best cold tests are performed using solid carbon dioxide [-78ºC] or difluordichlormethane [-50ºC]); pain on percussion or palpation; periapical swelling; and abnormal mobility.
Pulp tests such as solid carbon dioxide or difluordichlormethane can be used to determine the return of pulpal sensation and revascularization, which can be detected as soon as 4 weeks after reimplantation. If there is no sign of revascularization after 4 months, it can be assumed that the pulp is necrotic and root canal therapy can be instituted.
Category 3—Clinical Procedure
(1) Endodontic access should be achieved through the incisal edge of the tooth. This will facilitate the complete instrumentation of the canal. Immature teeth are very difficult to instrument thoroughly. Having straightline access to the apex will facilitate instrumentation.
(2) Clean and shape the canal with rotary instruments to as large a file as possible using chlorhexidine as an irrigant. Avoid initial use of sodium hypochlorite. This agent can cause damage to the preodontoblasts that are in the apical region. (These cells will produce the calcified tooth structure.)
(3) Instrument with Hedstrom-type files to a size 140.
(4) Dry the root canal.
(5) Place a thick layer of dry calcium hydroxide or calcium sulfate in the apical 2 to 3 mm of the canal.
(6) Place 5.25% sodium hypochlorite in the canal and leave in place for 15 minutes.
(7) Flush the sodium hypochlorite and file with Hedstrom files to a size 140.
(8) Dry the canal and place dry calcium hydroxide in the entire root canal space.
(9) Follow up with a radiograph every 3 months.
(10) If no sign of apical closure, change calcium hydroxide.
(11) When radiographic evidence of apical closure is evident, remove calcium hydroxide, reinstrument, and obturate with warm gutta-percha.
(12) Place a composite resin restoration.
(13) Do not use a post. Teeth with immature apices have fragile dentin walls and are subject to fracture.
Category 4—Open Apex, Nonbiologic Storage Prior to Reimplantation
At the reimplantation visit, the avulsed tooth should be placed into the socket to determine the fit. If the tooth does not fit, the tooth should be placed back in an optimum storage environment such as a Save-A-Tooth while the socket is appropriately modified. Curette the socket to remove the blood clot, foreign debris, or spicules of bone or tooth. Using gentle pressure, guide the tooth into its normal position. Endodontic treatment for Category 4 teeth can be performed extraorally prior to reimplantation or after reimplantation.
Category 4—Clinical Procedure
(1) Achieve access through the incisal edge of the tooth as described above and for the same reasons.
(2) Instrument the canal with rotary instruments and Hedstrom files.
(3) Soak the prepared tooth in 5.25% sodium hypochlorite for 30 minutes to remove all of the PDL from the external surface of the root and the remaining pulp tissue from the canal.
(4) Soak the tooth in 2% stannous fluoride for 5 minutes and 1 mL/20 mg of doxycycline for an additional 5 minutes.
(5) Obturate the canal with mineralized trioxide aggregate or calcium hydroxide in the apical half and then with gutta-percha in the coronal half.
(6) Seal the access with a composite resin or glass ionomer restoration.
(7) Cover the root surface with the periodontal regenerative therapy Emdogain (Biora, Inc), and fill the socket with Emdogain.7,8
(8) Replant the tooth and place a functional splint for a maximum of 2 weeks. The optimal splint is orthodontic brackets with wire.
(9) Radiographically examine the tooth every 3 months for signs of apical calcification and an intact lamina dura.
All reimplanted avulsed teeth should be followed at 1 year intervals for 5 years. If resorption is observed, a new attempt at disinfection of the root canal space by standard re-treatment can reverse the process. If signs of replacement resorption are seen, no treatment will halt the process, and the patient (and parents, if applicable) should be told that the tooth will eventually be lost.
By using an appropriate storage system such as a Save-A-Tooth and having knowledge of appropriate treatment options, an avulsed tooth can be reimplanted with the greatest chance of success. Using the different categories of avulsed teeth discussed in this article as a guide, the clinician can determine the most applicable course of treatment. If endodontic treatment is based on the clinical condition of the pulp and PDL cells, the chance of success following reimplantation is improved.
1. Krasner P, Rankow HJ. New philosophy for the treatment of avulsed teeth. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 1995;79:616-623.
2. Krasner P. Advances in the treatment of avulsed teeth. Dent Today. 2003;22:84-87.
3. Krasner P, Person P. Preserving avulsed teeth for replantation. J Am Dent Assoc. 1992;123:80-88.
4. Hiltz J, Trope M. Vitality of human lip fibroblasts in milk, Hanks balanced salt solution and Viaspan storage media. Endod Dent Traumatol. 1991;7:69-72.
5. Trope M, Friedman S. Periodontal healing of replanted dog teeth stored in Viaspan, milk and Hank's balanced salt solution. Endod Dent Traumatol. 1992;8:183-188.
6. Blomlof L. Milk and saliva as possible storage media for traumatically exarticulated teeth prior to replantation. Swed Dent J Suppl. 1981;8:1-26.
7. Trope M. Clinical management of the avulsed tooth: present strategies and future directions. Dent Traumatol. 2002;18:1-11.
8. Trope M. Traumatic injuries. In: Cohen S, Burns RC, eds. Pathways of the Pulp. 8th ed. St Louis, Mo: Mosby; 2002:chap 16.
9. Treatment of the avulsed permanent tooth. Recommended Guidelines of the American Association of Endodontists. Dent Clin North Am. 1995;39:221-225.
10. Andreasen JO. Exarticulations. In: Andreasen JO, ed. Traumatic Injuries of the Teeth. 2nd ed. Philadelphia, Pa: WB Saunders; 1981.
11. Lindskog S, Pierce AM, Blomlof L, et al. The role of the necrotic periodontal membrane in cementum resorption and ankylosis. Endod Dent Traumatol. 1985;1:96-101.
Disclosure: Dr. Krasner is the developer of the Save-A-Tooth System (888-788-6684).
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