Intentional Replantation: No Longer a Last Resort for Saving a Natural Tooth

Su-Min Lee, DDS, DMD, MSD, DScD; and Michael Marmo, DMD

Persistent apical periodontitis following endodontic treatment may be attributed to resistant intra- and extraradicular microorganisms, cysts, cholesterol crystals, and foreign bodies.¹ In cases where conservative retreatment or root-end microsurgery proves ineffective or unfeasible, intentional replantation (IR) emerges as a reliable and predictable solution.

Intentional replantation refers to the intentional extraction of a tooth followed by its replacement back into its socket to perform a root-end surgery or other necessary repairs. Once considered a treatment plan of last resort, IR has become highly predictable, with retention rates reported at 88% to 93%.^2,3 These favorable outcomes emanate from advancements in modern apical microsurgery, including atraumatic extraction techniques, minimized extraoral time, preservation of the periodontal ligament (PDL), and utilization of biocompatible root-end filling materials. Notably, IR represents a cost-effective option for preserving a natural tooth and avoiding the need for implant placement after extraction.⁴

Indications

IR has emerged as a favorable alternative to conventional microsurgery, especially when surgical access is restricted due to specific anatomical challenges. For mandibular second molars with lingually inclined roots in close proximity to the inferior alveolar nerve, accessing the root apices becomes extremely difficult. The bony thickness to reach the mesial and distal root apices in these teeth averages 7.34 mm and 8.51 mm, respectively,⁵ limiting traditional osteotomy and root resection. Similarly, accessing maxillary second molars without creating a sinus communication poses limitations. Reaching the palatal root from a buccal approach proves challenging, and from the palate, there are risks of damaging the greater palatine artery and nerve. Additionally, the proximity of the mental foramen (averaging 5 mm from the nearest premolar root apex⁶) increases the risk of postoperative paresthesia, making IR a preferred option in such situations.

Other indications for IR include communication or perforation cases, where reaching the repair site would require excessive bone removal. Notably, Krug et al reported a successful case of extensive cervical resorption repair and replantation without sacrificing healthy bone.⁷ Mandibular first premolars with mesiolingual lesions, inaccessible even after conservative retreatment and endodontic microsurgery, also benefit from IR.⁸ Additionally, when dealing with separated instruments beyond the apex or in cases of gross overfill or non-negotiable canals associated with periapical radiolucencies and no feasible surgical approach, IR can be an advantageous treatment option. Moreover, IR serves as a beneficial alternative for patients who are unwilling or unable to undergo conventional microsurgical procedures.

Case Selection

Thorough treatment planning is essential for achieving favorable results with IR. Preoperative cone-beam computed tomography (CBCT) scan imaging provides a 3-dimensional confirmation of root anatomy, enabling the extraction of a multi-rooted tooth in its entirety. The ideal candidate for IR is a tooth with straight roots and a substantial volume of interseptal bone, as it provides the necessary support once the tooth is replanted. Teeth with fused roots but lacking interseptal bone are relatively easier to remove but may lack stability upon reinsertion.⁹ Conversely, teeth with wide or dilacerated roots are unfavorable for IR, because extracting them without fracture is challenging or not possible. Interestingly, periodontal involvement does not serve as an absolute contraindication for IR. In some cases, teeth with one or two pockets ≥6 mm have been successfully retained through IR,¹⁰ which demonstrates its potential effectiveness in managing periodontally involved teeth.

Treatment Protocols

The success of IR largely depends on the atraumatic extraction of the tooth as well as its careful, delicate handling during and after the procedure. Limiting the extraoral time to less than 15 minutes is recommended.¹¹ Figure 1 presents a step-by-step protocol for IR. The clinician begins by gripping the tooth just slightly above the cementoenamel junction using extraction forceps. Controlled force is applied to gradually expand the bone plates. The tooth is then passively luxated, with care taken to avoid damaging the cervical area or causing a fracture. When a tooth is being fully luxated and is on the verge of coming out of the socket, a rubber band is placed around the handle of the forceps and remains in place throughout the procedure. This allows the tooth to be held firmly in the forceps and prevents its accidental dropping as well as damage to PDL cells. The rubber band will be removed after repositioning the tooth into the socket.

After the extraction, in order to maintain viable PDL cells, it is advised not to perform apical curettage of the extraction socket. If any granulation tissue is observed, it is recommended to use surgical suction to remove as much of it as possible without touching the alveolar walls. Subsequent to the extraction, to protect the socket from debris and saliva, the patient is instructed to bite gently on a sterile gauze placed on the socket. This should continue until the tooth is prepared for replantation.

After a successful extraction, the tooth is transferred from the socket to a basin filled with Hank's Balanced Salt Solution (HBSS) (Cyagen, cyagen.com) or Pedialyte^® (Abbott, pedialyte.com). This basin serves as the site for the tooth for the remaining steps of the procedure. The tooth must be constantly immersed in the selected medium, which provides hydration to and support of PDL cells, thereby maintaining their viability for up to 30 minutes.¹¹ A quick visual examination of the tooth is then conducted to identify any gross fractures. Next, a Lindemann surgical bur or any straight carbide bur is used to resect 3 mm of the root tip, ensuring that no bevel is created.

Following root resection, the apex is stained with methylene blue and examined under high magnification through a microscope to observe anatomical variations, the presence of an isthmus, missed canals, and any signs of fracture. Subsequently, root-end preparation is carried out using a #330 carbide bur, reaching a depth of approximately 3 mm. The #330 bur is used instead of ultrasonic tips to reduce the time required for root-end preparation. For the root-end filling, either mineral trioxide aggregate (ProRoot^® MTA, Dentsply Sirona, dentsplysirona.com) or bioceramic putty (Endosequence^® BC Sealer^™, Brasseler USA, brasselerusadental.com) is placed. These materials possess a hydrophilic nature, biogenic properties, and zero shrinkage. During the root-end surgery, which is performed extraorally, the dental assistant consistently applies HBSS or Pedialyte to the root surface to prevent drying of the PDL cells. Once the material is condensed, the tooth is gently inserted back into its socket, and finger pressure is applied to compress the buccal and lingual cortical plates. The patient is then instructed to bite down gently.

Splinting is rarely necessary and should only be considered when a tooth has significant instability. For an unstable tooth, a semi-rigid splint may be applied using fishing line or orthodontic wire bonded to the one or two adjacent teeth with flowable resin. The patient should be instructed to follow a soft diet for 1 to 2 weeks. The duration of splint application may vary from 1 to 4 weeks.^3,12 Unnecessary splinting should be avoided, as it can result in ankylosis, which is the primary cause of failure in replantation procedures. If necessary, sutures can be placed in a non-taut, diagonal manner to reduce mobility and the occurrence of ankylosis. By following these recommended steps, IR procedures can be effectively performed, ensuring optimal conditions for the viability of PDL cells and successful outcomes. Figure 2 presents an intentional replantation case.

Healing Process

The key to achieving success with IR lies in re-establishing the PDL upon replantation and allowing for a healing period. This process is essential for restoring both functional mobility and stability to the replanted tooth. The overall timeline for complete re-establishment of a functionally oriented PDL is approximately 4 months.^9,11 Within 3 days post-operation, a blood clot forms between the two separated layers of the PDL. By day 7, further periodontal healing is observed, characterized by the attachment of junctional epithelium and the presence of disorganized fibroblasts within the severed PDL. After 1 month, the PDL displays a normal radiographic appearance, but histologically the connective tissue will still be in the process of maturing.¹¹ Finally, at the 4-month mark, the re-establishment of a functionally oriented PDL can be observed. Patients should understand and adhere to this timeline, so they can have realistic expectations regarding the complete restoration of a functional PDL.

Outcomes

Successful cases of IR have been reported since the 1960s.¹³ With the use of modern techniques and materials, the cumulative retention rate of replanted teeth can reach up to 93% over a 12-year period, with a healing rate of 77% after 3 years.³ Furthermore, a fairly recent meta-analysis demonstrated a survival rate of 89.1% for intentionally replanted teeth with mean extraoral time ranging from 2.15 to 12.5 minutes. This highlights the cost-effectiveness of replantation as an alternative to single-tooth implants.⁴ In cases where replantation is unsuccessful, an implant remains a viable option.

Most complications in IR tend to occur within the first year after treatment.³ These complications are often attributed to replacement resorption (ankylosis), inflammatory root resorption, or a persistent periapical radiolucency, which can lead to discomfort and eventual tooth extraction. A meta-analysis by Torabinejad et al reported a mean prevalence of 11% for root resorption,² while Javed et al noted an occurrence of ankylosis ranging from 0% to 25%.¹⁴ It is, therefore, crucial to closely monitor IR cases for at least 3 years to identify and address any potential late complications that may arise.

Conclusion

Considered by some to be a wonder of endodontics, intentional replantation enables the extraction, repair, and successful replantation of a tooth. IR has become a well-established and scientifically supported treatment modality in endodontics due largely to advancements in magnification, bioceramics, and instruments. A cost-effective option compared to implant placement, the procedure is often greatly appreciated by patients. Endodontists are encouraged to raise awareness among their dental colleagues regarding this viable treatment option for patients, whenever it is applicable.

Disclosure

The authors have no conflicts of interest related to this article.

About the Authors

Su-Min Lee, DDS, DMD, MSD, DScD
Assistant Professor of Endodontics and Director of Endodontic Clinic, Department of Endodontics, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Diplomate, American Board of Endodontics

Michael Marmo, DMD
Clinical Associate Professor of Endodontics, Department of Endodontics,
School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania;
Private Practice in Endodontics, Newtown, Pennsylvania; Diplomate, American Board of Endodontics

References

1. Siqueira JF Jr. Aetiology of root canal treatment failure: why well-treated teeth can fail. Int Endod J. 2001;34(1):1-10.

2. Torabinejad M, Dinsbach NA, Turman M, et al. Survival of intentionally replanted teeth and implant-supported single crowns: a systematic review. J Endod. 2015;41(7):992-998.

3. Cho SY, Lee Y, Shin SJ, et al. Retention and healing outcomes after intentional replantation. J Endod. 2016;42(6):909-915.

4. Mainkar A. A systematic review of the survival of teeth intentionally replanted with a modern technique and cost-effectiveness compared with single-tooth implants. J Endod. 2017;43(12):1963-1968.

5. Jin GC, Kim KD, Roh BD, et al. Buccal bone plate thickness of the Asian people. J Endod. 2005;31(6):430-434.

6. von Arx T, Friedli M, Sendi P, et al. Location and dimensions of the mental foramen: a radiographic analysis by using cone-beam computed tomography. J Endod. 2013;39(12):1522-1528.

7. Krug R, Soliman S, Krastl G. Intentional replantation with an atraumatic extraction system in teeth with extensive cervical resorption. J Endod. 2019;45(11):1390-1396.

8. Yu YH, Kim M, Kratchman S, Karabucak B. Surgical management of lateral lesions with intentional replantation in single-rooted mandibular first premolars with radicular groove: 2 case reports. J Am Dent Assoc. 2022;153(4):371-381.

9. Kratchman S. Intentional replantation. Dent Clin North Am. 1997;41
(3):603-617.

10. Cho SY, Lee SJ, Kim E. Clinical outcomes after intentional replantation of periodontally involved teeth. J Endod. 2017;43(4):550-555.

11. 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(5):183-188.

12. Becker BD. Intentional replantation techniques: a critical review. J Endod. 2018;44(1):14-21.

13. Grossman LI. Intentional replantation of teeth. J Am Dent Assoc. 1966;72(5):1111-1118.

14. Javed F, Zafar K, Khan FR. Outcome of intentional replantation of endodontically treated teeth with periapical pathosis: a systematic review and meta-analysis. Aust Endod J. 2023;49 suppl 1:494-507.