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Guidelines for autotransplantation of developing premolars to the anterior maxilla
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Guidelines for autotransplantation of developing premolars to the anterior maxilla Ewa Monika Czochrowska, and Pawe» Plakwicz Loss of a permanent maxillary central incisor in a young patient is a therapeutic challenge for dental professionals. Autotransplanted developing premolars replacing missing maxillary incisors provide predictable long-term results and assure bone preservation during growth. Moreover, they can be successfully transformed to the morphology of the missing incisors, which is very important since these teeth are placed centrally in the esthetic zone. Comprehensive interdisciplinary treatment planning is necessary, combining a thorough evaluation of the occlusion and the profile, existing indications for premolar removal, space conditions, and the optimal match between the donor tooth and the recipient site. Orthodontic space management before and after surgery is often needed to create favorable conditions for donor accommodation, and to establish both normal occlusion and a good esthetic result. Monitoring of pulpal and periodontal healing and root development after transplantation of developing premolars is mandatory during follow-up appointments. (Semin Orthod 2020; &:1–12) © 2020 Elsevier Inc. All rights reserved.
Introduction ne of the most important indications for tooth autotransplantation is traumatic loss of maxillary incisors in young patients. Upon the loss of an upper anterior tooth, patients and parents are usually very alarmed and seek expert help with the main request to explain all possible treatment options, and to select the best solution for the individual situation. Gaining informed consent after a thorough discussion with patients and parents/guardians about potential complications and alternative solutions must precede the initiation of any treatment. Autotransplanation of developing premolars has been reported to be a successful long-term treatment alternative in growing patients with congenitally missing or traumatically lost teeth.1-5
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Associate Professor, Department of Orthodontics, Medical University of Warsaw, Poland; Associate Professor, Department of Periodontology, Medical University of Warsaw, Poland. Corresponding author: Ewa Czochrowska, Department of Orthodontics, Medical University of Warsaw, ul. Binieckiego 6, 02-097 Warsaw, Poland. E-mail: [email protected] © 2020 Elsevier Inc. All rights reserved. 1073-8746/12/1801-$30.00/0 https://doi.org/10.1053/j.sodo.2020.01.007
The advantages of this method include immediate replacement of a missing tooth, good adaptation of the transplanted tooth to growth changes, and normal response to orthodontic forces. These features are very important in children and young adolescents for whom dental implants are generally contraindicated.6-8 Transplanted developing premolars have a good potential for long-term preservation of hard and soft periodontal tissues.3,9 Orthodontic mesialization of lateral incisors, which is another viable alternative to replace a missing central incisor in a young patient, is a long and complex treatment after the eruption of all permanent teeth.10 Moreover, tooth width at the gingival level is usually more favorable for premolars than for lateral incisors, which is an important factor for satisfactory esthetics of the restoration to resemble the missing central incisor.10,11 Developing premolars have good surgical access, which facilitates their gentle removal - a crucial predictor for successful outcome.12-14 In addition, premolars are frequently extracted for orthodontic purposes, which is another reason why they can serve as tooth replacements in case of need.15 When tooth transplantation is
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considered as an alternative to replace traumatically lost maxillary incisors, developing premolars with 1/2 to 3/4 of the final root length are the best donors for a successful outcome.16,17 Dental injuries often occur in children at the time of incomplete premolar root development, which may correspond well with the possibility of using these teeth as donors to replace traumatized incisors (Figs. 1 3).
Donor selection Selection of a premolar as a donor tooth to replace a missing maxillary incisor, depends on: - orthodontic indications for its removal, - surgical assessment of the optimal match between the donor tooth and the recipient site, - long-term prognosis, and
Figure 1. A 9-year old boy sought orthodontic treatment for his unerupted maxillary left central incisor and reverse overjet (A, B). The panoramic radiograph evidenced an impacted, dilacerated maxillary incisor on the left side (C), which was scheduled for extraction due to its unfavorable crown-to-root angulation. Due to the patient’s Class III tendency, autotransplantation of the unerupted mandibular left first premolar (circle) was planned to substitute the dilacerated incisor The transplanted premolar did not erupt 8 months after the transplantation and therefore orthodontic extrusion was performed to confirm the presence of ankylosis (D), which was not clearly visible on the intraoral radiograph (E). The panoramic radiograph taken after confirmation of ankylosis of the transplant, showed that the mandibular right first premolar was still unerupted (circle) and that its root development was favorable for a second premolar transplantation (2/3 root growth completed) (F). The ankylosed transplant was extracted and the second transplantation was performed. The transplanted mandibular premolar erupted spontaneously into occlusion after 4 months (G). Radiographic signs of pulp obliteration and root growth were detected (H, I). Space opening was performed before reshaping of the transplant in order to secure an optimal match between its width and the width of the adjacent natural central incisor (J). A direct composite build-up was placed following the long axis of the transplant and matching the length of the reference incisor (K). After orthodontic treatment normal overjet and overbite were achieved (L). Pulp obliteration of the transplanted premolar is present 2 years after the surgery (M).
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Figure 1. Continued
- careful weighing of all pros and cons compared with other treatment modalities. Comprehensive interdisciplinary evaluation of a prospective candidate is mandatory to select the donor tooth, which will have the most favorable prognosis for successful healing, satisfactory esthetics, and good function in the long term.
Orthodontic indications Comprehensive evaluation of the individual characteristics of each patient include: occlusion and profile, space conditions, the number of teeth missing, the availability of suitable donors, post-treatment stability and patient’s expectations. Preferably, extraction of a donor tooth should also be indicated from the orthodontic perspective, and not only because of incisor loss.18 In this case, the general indications for the selection of a donor premolar to replace a missing maxillary central incisor are the same as orthodontic indications for premolar extraction. Upper first premolars are less appropriate as donors because of their morphology and the arising difficulty to accommodate a double-rooted premolar in the anterior maxilla. Reportedly, these teeth have a lower potential for successful healing after autotransplanation.19,20
While maxillary second premolars are a good choice in patients with Class II malocclusion, mandibular premolars are the better choice in patients with Class III malocclusions (Fig. 1). In patients with dental Class I relationships and missing maxillary central incisors, it is advantageous to choose the upper second premolars, because space closure in the lower arch is more difficult, even if skeletal temporary anchorage devices (TADs) are utilized. Sometimes, after removal of the maxillary second premolars, the remaining spaces close spontaneously by mesialization and rotation of the first molars around their palatal root. For each patient radiological examination using cone-beam computed tomography (CBCT) is mandatory to evaluate individual morphological variations of the premolars in order to assess the best match between the donor and the recipient site. Unilateral replacement of a central incisor requires management of the asymmetry created in the dental arch after removal of a donor premolar from one quadrant. Compensatory extractions or the use of TADs are effective treatment strategies to assist orthodontic tooth movements, and to obtain normal dental relationships after premolar transplantation for substitution of a single incisor loss. If spontaneous space closure at the donor site is intended, upper second premolars are usually the best choice.
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It is inadvisable to select the donor premolar from the same quadrant as the lost maxillary incisor, because this would worsen the initial problem in case of failure. If the transplant fails, mesializiation of maxillary lateral incisors still remains an alternative solution. When two maxillary central incisors are missing, the mandibular premolars should be selected as donors (Fig. 2). Selection of a mandibular premolar in patients with dental Class I and II relationships to replace missing central incisors will increase the orthodontic problem, and necessitates either optimum patient collaboration with fulltime wear of Class II elastics, or the use of TADs or Herbst-type anchorage reinforcement appliances for space closure in the lower arch. (Fig. 2). However, the overwhelming advantages of replacing a missing maxillary incisor in young
patients with a natural substitute may support the choice of premolar transplantation, even if premolar extraction is not indicated from the orthodontic perspective. When autotransplantation of developing premolars is considered in older children, selection of an optimal donor (an unerupted premolar), might be limited because of advanced root formation (Fig. 2). Therefore, treatment planning including autotransplanation of developing premolars should be initiated as early as possible following trauma. Timely planning of premolar transplantation, when all premolars are still unerupted, helps to select the optimal donor tooth from an orthodontic perspective, to secure a good match between the stage of root development and the recipient site, and to promote successful healing and a good esthetic outcome.
Figure 2. A 10-year old boy with an increased overjet and severe traumatic injury of his maxillary central incisors was scheduled for extraction of the compromised teeth. Autotransplantation of both mandibular second premolars was performed to replace the missing incisors, as these were the only unerupted premolars present (A). Normal healing after transplantation with pulp obliteration, eruption of the transplants, and continuous root development could be radiographically evidenced (B-D). Orthodontic treatment with fixed appliances and a Class II corrector (Forsus, 3M Unitek) was started two years after transplantation with the aim to correct the overjet and to close the lower extraction spaces (E-J). After closing the spaces in the lower arch, the premolar brackets were removed and the transplants were reshaped using direct composite build-ups without any enamel grinding. The incisor brackets were subsequently bonded (K, L). Satisfactory occlusal relations and closure of the extraction spaces were achieved after the orthodontic treatment (M-Q). Intraoral radiographs confirmed normal root development after transplantation including pulp obliteration (R, S).
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Figure 2. Continued
Surgical planning of autotransplantation Two major issues need to be addressed at the time when surgical autotransplantation of a developing premolar to the anterior maxilla is planned. They include:
the morphology of all potential donor premolars indicated by the orthodontist, the space between teeth adjacent to the recipient site and bone conditions.
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The morphology of developing premolars and selection of the best donor tooth Based on occlusal conditions and patient needs, the orthodontist indicates the potential donor tooth/teeth for autotransplantation. Premolars differ not only in shape and size, but also in inclination in the alveolar process during eruption, which is an important feature from the surgical perspective. Impacted premolars are generally more difficult, if not impossible, to remove gently, which is a prerequisite for successful healing. Upper first premolars have usually two clearly separate roots and their cumulative bucco-palatal dimension may exclude their accommodation within the volume of the alveolus along the entire root length. Upper second premolars are often smaller since their roots are often close to each other, making them the preferable donors for maxillary autotransplantation compared to first maxillary premolars. Mandibular premolars, both first and second, are usually the smallest and the easiest ones to remove from their alveolar crypt and to accommodate in the recipient site in the anterior maxilla, and for this reason surgically preferred as replacement of maxillary incisors. The downside is that orthodontic indications for their removal are not easy to find. In cross-section, mandibular premolars are less oval and more rounded when compared to the maxillary premolars, and the lingual cusp is less pronounced, requiring less grinding when the final shaping of the incisor is performed.
Space and bone conditions at the recipient site The amount of space at the recipient site should ensure safe preparation of the new artificial socket, which is created parallel between the roots of the adjacent teeth. The size of the new socket should be wider then the cross-section of the root, providing approximately 1 mm of space around the entire surface of the root. The oval cross-section of the artificial socket corresponding to the morphology of most roots of premolars differs from the triangular or round cross-section of the existing incisor alveolus, especially in the vestibulo-palatal dimension at the coronal part of the root. When the characteristics of the donor tooth and the recipient site do not match, other options in terms of
selection of an alternative donor tooth or changing the feature that prevents transplantation to the recipient site need to be considered.
Key aspects of the surgical procedure According to a recent study of Jakobsen,21 the success of transplantation does not depend on the experience of the surgeon. This is contrary to the findings of a previous study by Schwartz et al.,13 who reported that the surgeon’s experience improves treatment outcomes. Surgery may be performed under local or general anesthesia depending on the patient’s cooperation and psychological status, and on the operator’s experience. However, general anesthesia with nasal intubation is reasonable for more complex cases (e.g. transplantation of two or more premolars). If the deciduous molar is still present over its premolar successor, it is simply extracted with a forceps; if ankylosis is detected, the tooth must be separated into fragments and gently removed. The buccal and coronal part of the bone over the donor’s crypt is removed until the premolar can be easily reached. Special effort should be made to avoid direct contact of any instrument with the surface of the donor root, which requires that the inner thin layer of bone that stays in direct contact with the periodontal ligament of the root, is not drilled with a bur, but only gently deflected from the root surface with a small elevator. Most studies describe preparation of the recipient site with rotary instruments (straight or contra-angled handpieces with either round or conical burs of large diameter), chisels, or more recently, piezosurgery has been proposed. If the traumatized incisor is still present, preparation of the new socket can be mostly performed without elevation of a flap, which allows easy adaptation of the soft tissues around the transplant. However, preparation of the flapless socket without increasing the risk of trauma to the adjacent teeth is more difficult due to the extremely limited visual control of the adjacent structures. In most cases, the initial size of the socket must be enlarged for ensuring a loose accommodation of the donor within the walls of the new artificial bed. Since the premolar root is usually bigger than the root of an incisor, osteotomy involves the removal of labial alveolar bone of about 1/3 to 1/2 of the coronal socket height,
ARTICLE IN PRESS Guidelines for autotransplantation of developing premolars to the anterior maxil
deliberately creating a labial bone dehiscence. The artificial socket should also provide 2-3 mm of extra- space apically to accommodate the soft tissues of the donor root apex. In cases with a time lag between incisor loss and transplantation surgery, a significant vertical and horizontal bone defect might be detected at the recipient site. In these situations, flap preparation becomes necessary. The mucosal tissue covering the resorbed buccal and marginal bone is deficient, the keratinized gingiva is narrow, and scars are present, which makes flap handling difficult. For this reason, the flap is usually extended to at least one adjacent tooth on each side, and vertical releasing incisions are performed to ensure better visual inspection of
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bone and adjacent roots (Fig. 3A-B). In patients with pre-existing horizontal bone atrophy, the socket is usually a three-wall defect with a labial dehiscence created during surgery (Fig. 3C). Once the socket is ready, the donor tooth is removed from the crypt with forceps or elevators, which should only contact the coronal portion of the tooth, clearly distant from the periodontal ligament covering the root in presence of the dental follicle. Should the dental follicle still surround the donor crown, it can be gripped with surgical forceps and extracted together with the tooth inside. The donor should be directly transferred to the recipient socket without any delay. Because of the labial dehiscence, the buccal root surface of the premolar may partially lack bony
Figure 3. Surgery in a 10 year-old patient is described in Figure 2. Autotransplantation of the mandibular right and left second premolars to replace both traumatized central incisors; incision and flap elevation (A) after extraction of the resorbed central incisors - note the existing labial fenestration over the left incisor (B), surgical labial bone dehiscences created during preparation of new sockets (C), second mandibular premolars placed in new sockets with labial exposure of the coronal parts of their roots (D), suturing of the flap over the premolar crowns (E). The status of the soft tissues at the time of suture removal 3 weeks after surgery, (F).Cone Beam Computed Tomography scans performed 5 years later prove regeneration of a normal labial cortical plate (G,H, I).
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coverage, but the apical portion should be placed within the alveolus (Fig. 3D). Depending on the stage of root development, the transplant may be placed at the level of marginal gingiva or in a more advanced eruption stage. Different protocols for stabilization of the transplant have been described; however, most studies support the finding that flexible splinting with sutures alone (Fig. 3E) decreases the risk of complications of periodontal healing.22,23 In patients with a short anterior maxilla (due to the individual growth pattern or significant posttraumatic atrophy of the alveolus), smaller premolars with shorter roots (1/2 instead of 3/4 root development) should be selected. In order to prevent bacterial infection during early stages of healing, systemic antibiotic is recommended after surgery. Additionally, according to a systematic review by Chung et al.,23 antibiotic prophylaxis reduces the risk of inflammatory, infection-related root resorption, and postoperative failure rate. The patient is advised to take non-steroidal anti-inflammatory drugs for 2-3 days, and to apply a chlorhexidine gel on the operated area until the sutures/splinting is removed two weeks after surgery (Fig. 3F). Subsequently, the patient can resume normal masticatory function regardless of the transplanted tooth.
Follow-up after transplanation Monitoring after tooth transplantation is necessary to evaluate periodontal healing, postsurgical root development, and to detect any signs of pathology. After transplantation of developing teeth, typical parameters to evaluate include pulp obliteration, tooth eruption (for donors which were placed at the level of gingiva or subgingivally to continue their eruption after surgery), and ongoing root formation (Figs. 1H, 1I, 2B-C, 2R).17,19,20 Pulp obliteration is a common finding in transplanted developing teeth. It is a sign of preserved pulp vitality and does not require endodontic therapy. In presence of a natural, contralateral premolar, comparing root development of the transplanted and non-transplanted premolar is very helpful to assess root formation. Periodic clinical and radiological examinations are necessary at least during the first 12 months after surgery. The protocol after transplantation of developing teeth includes
control examinations upon the removal of the suture (7-10 days), after 2, 6, 12, 18, 24 months, and then annually. In cases of uncertain healing, the follow-up appointments are scheduled every month until healing is established. The clinical examination includes assessment of tooth mobility, eruption and percussion sound. The radiological examination includes periapical radiographs of the transplanted premolar in order to monitor the healing of bone at the recipient site, root development, pulp obliteration of the transplanted premolar, and signs of different types of resorption. Horizontal growth of the new alveolar bone is expected several months after surgery.24,25 Regeneration of the labial cortical plate was reported even in sites where significant bone dehiscence was present at the time of surgery (Fig. 3G-I).26,27 Most complications of transplanted teeth with developing roots can be detected within the first year after surgery, however a longer observation period is always more reliable (Fig. 1A-F). Ankylosis is one of the most common complications after tooth transplantation, and is suspected when the transplant presents lack of normal mobility and a high metallic sound on percussion. Ankylosis of the transplant is confirmed when orthodontic force application does not move the tooth, while the adjacent teeth are tilting towards the transplant. Radiological examination of the root surface of the ankylosed tooth is usually not conclusive, because spot ankylosis is often not visible on radiographs (Fig. 1E-F).
Management of complications Impaired healing of the transplanted tooth is usually related to the surgical procedure, namely to the injury to the surface of the developing root and manifests itself typically as cervical root resorption or replacement resorption (ankylosis). Based on the authors’ clinical experience, ankylosis is the most serious complication after autotransplantation of developing premolars to the anterior maxilla. In case of complications, alternative solutions may include transplantation of another developing premolar (second transplantation), or orthodontic mesialization of the neighboring lateral incisor after extraction of the failed transplant (Fig. 1G-I).10 If a contralateral premolar is anyhow scheduled for extraction in
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order to achieve dental arch symmetry, it can then serve as a suitable donor for a second transplantation. Consequently, it is very important to carefully monitor transplanted teeth after surgery, because early detection of complications usually provides a better chance for a second transplantation (Fig. 1G-I). Preservation of an ankylosed transplant in the anterior maxilla in young children is usually not advisable, because of the unpredictable long-term prognosis and impaired smile esthetics.
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development can affect the development of their hard tissues. If premolars are transplanted during later stages of their root formation (about 3/4 of the final root length), it is usually recommended to wait 3-6 months after surgery to ascertain undisturbed healing.28 On the other hand, orthodontic mobilization shortly after transplantation (at about six weeks) was reported to decrease the risk for ankylosis after transplantation of more mature teeth.
Orthodontic repositioning for optimal reshaping Post-surgical orthodontics Most patients who have undergone autotransplantation of developing premolars to replace missing maxillary incisors need orthodontic treatment after surgery in order to: - close the space in the dental arch after removal of the donor premolar, - align the transplanted premolar in the dental arch, - level the gingival margins, - position the transplant for optimal reshaping to mimick the morphology of a natural incisor, or - correct a concomitant malocclusion. If the selection of a donor premolar is predominantly based on the optimal stage of root development rather than on orthodontic indications, anchorage control must be supplemented. TADs or Herbst-type Class II correctors may be helpful to assist planned tooth movements (Fig. 2). Alternative treatment options after removal of a donor premolar usually include prosthodontic substitution of the donor tooth with either partial fixed dentures (PFD) or dental implants after the end of growth.7,8 Transplantation of developing wisdom teeth constitutes another good option which may be performed before the cessation of growth depending on their root development. Orthodontic alignment of the transplanted premolar should preferably start after completion of the post-surgical healing phase. If donor premolars were transplanted at the earlier stages of root development, it is necessary to wait until root development reaches at least 3/4 of the final root length. Orthodontic repositioning of transplanted premolars at earlier stages of root
Orthodontic repositioning of the transplanted premolar after surgery significantly improves the esthetic outcome and should be recommended to the patient and parents/caregivers before surgery.11 Orthodontic repositioning of the transplanted premolar usually includes tooth alignment and levelling of the gingival margin between the transplanted premolar and the neighboring teeth, and should be performed using light forces, considering the transplant a traumatized tooth. It is often better to reshape the transplanted premolar before orthodontic repositioning, if the position of the transplant and its long axis need to be adjusted to the neighboring incisors. Sometimes, extra space is needed to match the width of the transplant with the natural central incisor. In this case, it is necessary to bond a premolar bracket on the unrestored transplanted premolar, and to open an adequate space for its reshaping (Figs. 1J, 2K). The optimal position of the zenith should be defined and respected. After the adequate space for reshaping is achieved, the premolar bracket is removed, and the morphology of the transplanted premolar is adapted to that of the central incisor using indirect or direct techniques. If further orthodontic repositioning of the reshaped transplant is necessary, a corresponding central incisor bracket is bonded, and the orthodontic treatment is continued until satisfactory alignment is obtained (Figs. 1K, 2L). It is usually easier to perform a good direct composite restoration of the transplanted premolar, if some mesial and distal space excess has been created (Fig. 1J-K). The palatal cusp of the transplanted premolar does not require grinding, because occlusal interferences can be avoided by palatally directed orthodontic tooth movement (Fig. 2K).
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Reshaping transplanted premolars in the anterior maxilla Transplanted teeth replacing traumatically lost maxillary incisors should not only have a good potential for successful healing, but also a favorable tooth form to match incisor morphology, as these teeth are placed in the center of the esthetic zone. Premolars have a comparable morphology to the width of maxillary
central incisors, which have the highest incidence of traumatic loss. A matching cervical width of the transplant and the lost incisor is critical, as only limited preparation of the transplant is possible during restorative treatment. Third molars, which are often considered as donor teeth, are mostly unsuitable for reshaping to maxillary incisors.29 Occasionally, supernumerary lateral incisors can be transplanted to the anterior maxilla.9
Figure 4. The maxillary right second premolar was transplanted to replace the traumatically injured maxillary left central incisor in a 9-years old girl (A). The transplanted premolar was reshaped to the incisor morphology with a direct composite build-up and orthodontic treatment was performed in order to align the transplanted tooth and to obtain normal occlusal relations (B). Four years after transplantation, the composite restoration was replaced by a feldspatic porcelain veneer to improve dental esthetics (C). The patient was satisfied with her smile after placement of the veneer (D).
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Contemporary techniques for reshaping autotransplanted premolars include the use of direct and indirect composite restorations or porcelain laminate veneers (PLV) (Figs. 1, 2, 4). The bonded restoration should not include any dentine preparation, because the presence of tertiary dentine in transplanted developing teeth may lead to different types of root pathology. Preferably, enamel reduction should also be avoided (Fig. 1J-L). Extensive grinding of premolars can interfere with pulp healing after surgery.28 If unerupted donor premolars are transplanted, they are usually placed under the gingiva or at the gingival level. It must be acknowledged that transplanted teeth should continue their root development and erupt similarly to normal developing teeth, hence the final restoration should only be placed after their full eruption. Post-surgical root development of a transplanted premolar depends on the initial stage of its root development upon surgery and may take more than two years in less mature premolars. Careful monitoring of the transplanted tooth by clinical inspection, and evaluation of a good quality intraoral radiograph of both the transplant and the control contralateral tooth, if present, is mandatory. Most frequently, the transplanted premolars are initially restored with composite material, and later receive PLVs (Fig. 4B-C). The introduction of 3-D technologies offers new options for fabrication of printed indirect restorations, which can be bonded on the transplanted teeth. PVLs offer the best biologic compatibility and esthetics and are thus recommended as “gold standard” procedure. Feldspathic PLVs are particularly indicated for minimally invasive reduction of hard tissues and good biomechanical properties (Fig. 4C-D).
Conclusions Autotransplanation of developing premolars is a viable treatment option for replacing missing maxillary central incisors in children and adolescents. It is necessary to evaluate the orthodontic indications for premolar removal and to match the morphology of the donor and the recipient site using CBCT assessment before treatment. Surgical damage to the root surface of the transplanted premolar must be avoided, and presurgical orthodontic space opening is frequently
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necessary. After surgery, healing and root development of the transplanted teeth requires periodic monitoring in order to detect early signs of failure. Post-surgical orthodontic repositioning of the transplanted premolar and reshaping or restoring them to incisor morphology is often indicated to ensure the best esthetic treatment result. Close interdisciplinary cooperation is imperative for achieving a successful long-term outcome.
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15. Czochrowska EM, Plakwicz P, Stenvik A. Dentoalveol€ares Wachstum beim Fehlen von Z€ahnen: Autotransplantation von wurzelunreifen Z€ahnen, kieferorthop€adischer L€ uckenschluss oder Implantatversorgung? Informationen aus Orthodontie & Kieferorthop€ a die. 2010;2:105–112. 16. Kristerson L. Autotransplantation of human premolars. A clinical and radiographic study of 100 teeth. Int J Oral Surg. 1985;14:200–213. 17. Andreasen JO, Paulsen HU, Yu Z, et al. A long-term study of 370 autotransplanted premolars. Part IV. Root development subsequent to transplantation. Eur J Orthod. 1990;12(1):38–50. 18. Stenvik A, Zachrisson BU. Orthodontic closure and transplantation in the treatment of missing anterior teeth. An overview. Endod Dent Traumatol. 1993;9:45–52. 19. Andreasen JO, Paulsen HU, Yu Z, Bayer T, Schwartz O. A long-term study of 370 autotransplanted premolars. Part II. Tooth survival and pulp healing subsequent to transplantation. Eur J Orthod. 1990;12(1):14–24. 20. Andreasen JO, Paulsen HU, Yu Z, Schwartz O. A longterm study of 370 autotransplanted premolars. Part III. Periodontal healing subsequent to transplantation. Eur J Orthod. 1990;12(1):25–37. 21. Jakobsen C, Stokbro K, Kier-Swiatecka E, et al. Autotransplantation of premolars: does surgeon experience matter? Int J Oral Maxillofac Surg. 2018;47(12):1604–1608. 22. Kristerson L, Andreasen JO. The effect of splinting upon periodontal and pulpal healing after autotransplanation of mature and immature permanent incisors in monkeys. Int J Oral Surg. 1983;12(4):239–249.
23. Chung WC, Tu YK, Lin YH, et al. Outcomes of autotransplanted teeth with complete root formation: a systematic review and meta-analysis. J Clin Periodontol. 2014;41 (4):412–423. 24. Paulsen HU, Andreasen JO. Eruption of premolars subsequent to autotransplantation. A longitudinal radiographic study. Eur J Orthod. 1998;20:45–55. 25. Michl I, Nolte D, Tschammler C, et al. Premolar autotransplantation in juvenile dentition: Quantitative assessment of vertical bone and soft tissue growth. Oral Surg Oral Med Oral Pathol Oral Radiol. 2017;124(1):1–12. 26. Plakwicz P, Wojtaszek J, Zadurska M. A new bone formation at the site of autotransplanted developing mandibular canines. A case report. Int J Periodontics Restorative Dent. 2013;33:13–19. 27. Plakwicz P, Czochrowska EM, Mielczarek A, et al. Vertical bone growth following autotransplantation of the developing maxillary third molar to replace a retained mandibular permanent molar: a case report. Int J Periodontics Restorative Dent. 2014;34(5):667–671. 28. Andreasen JO, Andersson L, Tsukiboshi M, Czochrowska EM. Autotransplantation of Teeth to the Anterior Region. In: Andreasen JO, Andreasen FM, Andersson L, eds. Textbook and Color Atlas of Traumatic Injuries to the Teeth. 5th Edition Wiley & Sons; 2018:853–875. 29. Plakwicz P, Fudalej P, Czochrowska E. Transplant vs implant in a patient with agenesis of both maxillary lateral incisors: A 9-year follow-up. Am J Orthod Dentofacial Orthop. 2016;149(5):751–756.
Guidelines for autotransplantation of developing premolars to the anterior maxilla Ewa Monika Czochrowska, and Pawe» Plakwicz Loss of a permanent maxillary central incisor in a young patient is a therapeutic challenge for dental professionals. Autotransplanted developing premolars replacing missing maxillary incisors provide predictable long-term results and assure bone preservation during growth. Moreover, they can be successfully transformed to the morphology of the missing incisors, which is very important since these teeth are placed centrally in the esthetic zone. Comprehensive interdisciplinary treatment planning is necessary, combining a thorough evaluation of the occlusion and the profile, existing indications for premolar removal, space conditions, and the optimal match between the donor tooth and the recipient site. Orthodontic space management before and after surgery is often needed to create favorable conditions for donor accommodation, and to establish both normal occlusion and a good esthetic result. Monitoring of pulpal and periodontal healing and root development after transplantation of developing premolars is mandatory during follow-up appointments. (Semin Orthod 2020; &:1–12) © 2020 Elsevier Inc. All rights reserved.
Introduction ne of the most important indications for tooth autotransplantation is traumatic loss of maxillary incisors in young patients. Upon the loss of an upper anterior tooth, patients and parents are usually very alarmed and seek expert help with the main request to explain all possible treatment options, and to select the best solution for the individual situation. Gaining informed consent after a thorough discussion with patients and parents/guardians about potential complications and alternative solutions must precede the initiation of any treatment. Autotransplanation of developing premolars has been reported to be a successful long-term treatment alternative in growing patients with congenitally missing or traumatically lost teeth.1-5
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Associate Professor, Department of Orthodontics, Medical University of Warsaw, Poland; Associate Professor, Department of Periodontology, Medical University of Warsaw, Poland. Corresponding author: Ewa Czochrowska, Department of Orthodontics, Medical University of Warsaw, ul. Binieckiego 6, 02-097 Warsaw, Poland. E-mail: [email protected] © 2020 Elsevier Inc. All rights reserved. 1073-8746/12/1801-$30.00/0 https://doi.org/10.1053/j.sodo.2020.01.007
The advantages of this method include immediate replacement of a missing tooth, good adaptation of the transplanted tooth to growth changes, and normal response to orthodontic forces. These features are very important in children and young adolescents for whom dental implants are generally contraindicated.6-8 Transplanted developing premolars have a good potential for long-term preservation of hard and soft periodontal tissues.3,9 Orthodontic mesialization of lateral incisors, which is another viable alternative to replace a missing central incisor in a young patient, is a long and complex treatment after the eruption of all permanent teeth.10 Moreover, tooth width at the gingival level is usually more favorable for premolars than for lateral incisors, which is an important factor for satisfactory esthetics of the restoration to resemble the missing central incisor.10,11 Developing premolars have good surgical access, which facilitates their gentle removal - a crucial predictor for successful outcome.12-14 In addition, premolars are frequently extracted for orthodontic purposes, which is another reason why they can serve as tooth replacements in case of need.15 When tooth transplantation is
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considered as an alternative to replace traumatically lost maxillary incisors, developing premolars with 1/2 to 3/4 of the final root length are the best donors for a successful outcome.16,17 Dental injuries often occur in children at the time of incomplete premolar root development, which may correspond well with the possibility of using these teeth as donors to replace traumatized incisors (Figs. 1 3).
Donor selection Selection of a premolar as a donor tooth to replace a missing maxillary incisor, depends on: - orthodontic indications for its removal, - surgical assessment of the optimal match between the donor tooth and the recipient site, - long-term prognosis, and
Figure 1. A 9-year old boy sought orthodontic treatment for his unerupted maxillary left central incisor and reverse overjet (A, B). The panoramic radiograph evidenced an impacted, dilacerated maxillary incisor on the left side (C), which was scheduled for extraction due to its unfavorable crown-to-root angulation. Due to the patient’s Class III tendency, autotransplantation of the unerupted mandibular left first premolar (circle) was planned to substitute the dilacerated incisor The transplanted premolar did not erupt 8 months after the transplantation and therefore orthodontic extrusion was performed to confirm the presence of ankylosis (D), which was not clearly visible on the intraoral radiograph (E). The panoramic radiograph taken after confirmation of ankylosis of the transplant, showed that the mandibular right first premolar was still unerupted (circle) and that its root development was favorable for a second premolar transplantation (2/3 root growth completed) (F). The ankylosed transplant was extracted and the second transplantation was performed. The transplanted mandibular premolar erupted spontaneously into occlusion after 4 months (G). Radiographic signs of pulp obliteration and root growth were detected (H, I). Space opening was performed before reshaping of the transplant in order to secure an optimal match between its width and the width of the adjacent natural central incisor (J). A direct composite build-up was placed following the long axis of the transplant and matching the length of the reference incisor (K). After orthodontic treatment normal overjet and overbite were achieved (L). Pulp obliteration of the transplanted premolar is present 2 years after the surgery (M).
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Figure 1. Continued
- careful weighing of all pros and cons compared with other treatment modalities. Comprehensive interdisciplinary evaluation of a prospective candidate is mandatory to select the donor tooth, which will have the most favorable prognosis for successful healing, satisfactory esthetics, and good function in the long term.
Orthodontic indications Comprehensive evaluation of the individual characteristics of each patient include: occlusion and profile, space conditions, the number of teeth missing, the availability of suitable donors, post-treatment stability and patient’s expectations. Preferably, extraction of a donor tooth should also be indicated from the orthodontic perspective, and not only because of incisor loss.18 In this case, the general indications for the selection of a donor premolar to replace a missing maxillary central incisor are the same as orthodontic indications for premolar extraction. Upper first premolars are less appropriate as donors because of their morphology and the arising difficulty to accommodate a double-rooted premolar in the anterior maxilla. Reportedly, these teeth have a lower potential for successful healing after autotransplanation.19,20
While maxillary second premolars are a good choice in patients with Class II malocclusion, mandibular premolars are the better choice in patients with Class III malocclusions (Fig. 1). In patients with dental Class I relationships and missing maxillary central incisors, it is advantageous to choose the upper second premolars, because space closure in the lower arch is more difficult, even if skeletal temporary anchorage devices (TADs) are utilized. Sometimes, after removal of the maxillary second premolars, the remaining spaces close spontaneously by mesialization and rotation of the first molars around their palatal root. For each patient radiological examination using cone-beam computed tomography (CBCT) is mandatory to evaluate individual morphological variations of the premolars in order to assess the best match between the donor and the recipient site. Unilateral replacement of a central incisor requires management of the asymmetry created in the dental arch after removal of a donor premolar from one quadrant. Compensatory extractions or the use of TADs are effective treatment strategies to assist orthodontic tooth movements, and to obtain normal dental relationships after premolar transplantation for substitution of a single incisor loss. If spontaneous space closure at the donor site is intended, upper second premolars are usually the best choice.
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It is inadvisable to select the donor premolar from the same quadrant as the lost maxillary incisor, because this would worsen the initial problem in case of failure. If the transplant fails, mesializiation of maxillary lateral incisors still remains an alternative solution. When two maxillary central incisors are missing, the mandibular premolars should be selected as donors (Fig. 2). Selection of a mandibular premolar in patients with dental Class I and II relationships to replace missing central incisors will increase the orthodontic problem, and necessitates either optimum patient collaboration with fulltime wear of Class II elastics, or the use of TADs or Herbst-type anchorage reinforcement appliances for space closure in the lower arch. (Fig. 2). However, the overwhelming advantages of replacing a missing maxillary incisor in young
patients with a natural substitute may support the choice of premolar transplantation, even if premolar extraction is not indicated from the orthodontic perspective. When autotransplantation of developing premolars is considered in older children, selection of an optimal donor (an unerupted premolar), might be limited because of advanced root formation (Fig. 2). Therefore, treatment planning including autotransplanation of developing premolars should be initiated as early as possible following trauma. Timely planning of premolar transplantation, when all premolars are still unerupted, helps to select the optimal donor tooth from an orthodontic perspective, to secure a good match between the stage of root development and the recipient site, and to promote successful healing and a good esthetic outcome.
Figure 2. A 10-year old boy with an increased overjet and severe traumatic injury of his maxillary central incisors was scheduled for extraction of the compromised teeth. Autotransplantation of both mandibular second premolars was performed to replace the missing incisors, as these were the only unerupted premolars present (A). Normal healing after transplantation with pulp obliteration, eruption of the transplants, and continuous root development could be radiographically evidenced (B-D). Orthodontic treatment with fixed appliances and a Class II corrector (Forsus, 3M Unitek) was started two years after transplantation with the aim to correct the overjet and to close the lower extraction spaces (E-J). After closing the spaces in the lower arch, the premolar brackets were removed and the transplants were reshaped using direct composite build-ups without any enamel grinding. The incisor brackets were subsequently bonded (K, L). Satisfactory occlusal relations and closure of the extraction spaces were achieved after the orthodontic treatment (M-Q). Intraoral radiographs confirmed normal root development after transplantation including pulp obliteration (R, S).
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Figure 2. Continued
Surgical planning of autotransplantation Two major issues need to be addressed at the time when surgical autotransplantation of a developing premolar to the anterior maxilla is planned. They include:
the morphology of all potential donor premolars indicated by the orthodontist, the space between teeth adjacent to the recipient site and bone conditions.
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The morphology of developing premolars and selection of the best donor tooth Based on occlusal conditions and patient needs, the orthodontist indicates the potential donor tooth/teeth for autotransplantation. Premolars differ not only in shape and size, but also in inclination in the alveolar process during eruption, which is an important feature from the surgical perspective. Impacted premolars are generally more difficult, if not impossible, to remove gently, which is a prerequisite for successful healing. Upper first premolars have usually two clearly separate roots and their cumulative bucco-palatal dimension may exclude their accommodation within the volume of the alveolus along the entire root length. Upper second premolars are often smaller since their roots are often close to each other, making them the preferable donors for maxillary autotransplantation compared to first maxillary premolars. Mandibular premolars, both first and second, are usually the smallest and the easiest ones to remove from their alveolar crypt and to accommodate in the recipient site in the anterior maxilla, and for this reason surgically preferred as replacement of maxillary incisors. The downside is that orthodontic indications for their removal are not easy to find. In cross-section, mandibular premolars are less oval and more rounded when compared to the maxillary premolars, and the lingual cusp is less pronounced, requiring less grinding when the final shaping of the incisor is performed.
Space and bone conditions at the recipient site The amount of space at the recipient site should ensure safe preparation of the new artificial socket, which is created parallel between the roots of the adjacent teeth. The size of the new socket should be wider then the cross-section of the root, providing approximately 1 mm of space around the entire surface of the root. The oval cross-section of the artificial socket corresponding to the morphology of most roots of premolars differs from the triangular or round cross-section of the existing incisor alveolus, especially in the vestibulo-palatal dimension at the coronal part of the root. When the characteristics of the donor tooth and the recipient site do not match, other options in terms of
selection of an alternative donor tooth or changing the feature that prevents transplantation to the recipient site need to be considered.
Key aspects of the surgical procedure According to a recent study of Jakobsen,21 the success of transplantation does not depend on the experience of the surgeon. This is contrary to the findings of a previous study by Schwartz et al.,13 who reported that the surgeon’s experience improves treatment outcomes. Surgery may be performed under local or general anesthesia depending on the patient’s cooperation and psychological status, and on the operator’s experience. However, general anesthesia with nasal intubation is reasonable for more complex cases (e.g. transplantation of two or more premolars). If the deciduous molar is still present over its premolar successor, it is simply extracted with a forceps; if ankylosis is detected, the tooth must be separated into fragments and gently removed. The buccal and coronal part of the bone over the donor’s crypt is removed until the premolar can be easily reached. Special effort should be made to avoid direct contact of any instrument with the surface of the donor root, which requires that the inner thin layer of bone that stays in direct contact with the periodontal ligament of the root, is not drilled with a bur, but only gently deflected from the root surface with a small elevator. Most studies describe preparation of the recipient site with rotary instruments (straight or contra-angled handpieces with either round or conical burs of large diameter), chisels, or more recently, piezosurgery has been proposed. If the traumatized incisor is still present, preparation of the new socket can be mostly performed without elevation of a flap, which allows easy adaptation of the soft tissues around the transplant. However, preparation of the flapless socket without increasing the risk of trauma to the adjacent teeth is more difficult due to the extremely limited visual control of the adjacent structures. In most cases, the initial size of the socket must be enlarged for ensuring a loose accommodation of the donor within the walls of the new artificial bed. Since the premolar root is usually bigger than the root of an incisor, osteotomy involves the removal of labial alveolar bone of about 1/3 to 1/2 of the coronal socket height,
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deliberately creating a labial bone dehiscence. The artificial socket should also provide 2-3 mm of extra- space apically to accommodate the soft tissues of the donor root apex. In cases with a time lag between incisor loss and transplantation surgery, a significant vertical and horizontal bone defect might be detected at the recipient site. In these situations, flap preparation becomes necessary. The mucosal tissue covering the resorbed buccal and marginal bone is deficient, the keratinized gingiva is narrow, and scars are present, which makes flap handling difficult. For this reason, the flap is usually extended to at least one adjacent tooth on each side, and vertical releasing incisions are performed to ensure better visual inspection of
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bone and adjacent roots (Fig. 3A-B). In patients with pre-existing horizontal bone atrophy, the socket is usually a three-wall defect with a labial dehiscence created during surgery (Fig. 3C). Once the socket is ready, the donor tooth is removed from the crypt with forceps or elevators, which should only contact the coronal portion of the tooth, clearly distant from the periodontal ligament covering the root in presence of the dental follicle. Should the dental follicle still surround the donor crown, it can be gripped with surgical forceps and extracted together with the tooth inside. The donor should be directly transferred to the recipient socket without any delay. Because of the labial dehiscence, the buccal root surface of the premolar may partially lack bony
Figure 3. Surgery in a 10 year-old patient is described in Figure 2. Autotransplantation of the mandibular right and left second premolars to replace both traumatized central incisors; incision and flap elevation (A) after extraction of the resorbed central incisors - note the existing labial fenestration over the left incisor (B), surgical labial bone dehiscences created during preparation of new sockets (C), second mandibular premolars placed in new sockets with labial exposure of the coronal parts of their roots (D), suturing of the flap over the premolar crowns (E). The status of the soft tissues at the time of suture removal 3 weeks after surgery, (F).Cone Beam Computed Tomography scans performed 5 years later prove regeneration of a normal labial cortical plate (G,H, I).
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coverage, but the apical portion should be placed within the alveolus (Fig. 3D). Depending on the stage of root development, the transplant may be placed at the level of marginal gingiva or in a more advanced eruption stage. Different protocols for stabilization of the transplant have been described; however, most studies support the finding that flexible splinting with sutures alone (Fig. 3E) decreases the risk of complications of periodontal healing.22,23 In patients with a short anterior maxilla (due to the individual growth pattern or significant posttraumatic atrophy of the alveolus), smaller premolars with shorter roots (1/2 instead of 3/4 root development) should be selected. In order to prevent bacterial infection during early stages of healing, systemic antibiotic is recommended after surgery. Additionally, according to a systematic review by Chung et al.,23 antibiotic prophylaxis reduces the risk of inflammatory, infection-related root resorption, and postoperative failure rate. The patient is advised to take non-steroidal anti-inflammatory drugs for 2-3 days, and to apply a chlorhexidine gel on the operated area until the sutures/splinting is removed two weeks after surgery (Fig. 3F). Subsequently, the patient can resume normal masticatory function regardless of the transplanted tooth.
Follow-up after transplanation Monitoring after tooth transplantation is necessary to evaluate periodontal healing, postsurgical root development, and to detect any signs of pathology. After transplantation of developing teeth, typical parameters to evaluate include pulp obliteration, tooth eruption (for donors which were placed at the level of gingiva or subgingivally to continue their eruption after surgery), and ongoing root formation (Figs. 1H, 1I, 2B-C, 2R).17,19,20 Pulp obliteration is a common finding in transplanted developing teeth. It is a sign of preserved pulp vitality and does not require endodontic therapy. In presence of a natural, contralateral premolar, comparing root development of the transplanted and non-transplanted premolar is very helpful to assess root formation. Periodic clinical and radiological examinations are necessary at least during the first 12 months after surgery. The protocol after transplantation of developing teeth includes
control examinations upon the removal of the suture (7-10 days), after 2, 6, 12, 18, 24 months, and then annually. In cases of uncertain healing, the follow-up appointments are scheduled every month until healing is established. The clinical examination includes assessment of tooth mobility, eruption and percussion sound. The radiological examination includes periapical radiographs of the transplanted premolar in order to monitor the healing of bone at the recipient site, root development, pulp obliteration of the transplanted premolar, and signs of different types of resorption. Horizontal growth of the new alveolar bone is expected several months after surgery.24,25 Regeneration of the labial cortical plate was reported even in sites where significant bone dehiscence was present at the time of surgery (Fig. 3G-I).26,27 Most complications of transplanted teeth with developing roots can be detected within the first year after surgery, however a longer observation period is always more reliable (Fig. 1A-F). Ankylosis is one of the most common complications after tooth transplantation, and is suspected when the transplant presents lack of normal mobility and a high metallic sound on percussion. Ankylosis of the transplant is confirmed when orthodontic force application does not move the tooth, while the adjacent teeth are tilting towards the transplant. Radiological examination of the root surface of the ankylosed tooth is usually not conclusive, because spot ankylosis is often not visible on radiographs (Fig. 1E-F).
Management of complications Impaired healing of the transplanted tooth is usually related to the surgical procedure, namely to the injury to the surface of the developing root and manifests itself typically as cervical root resorption or replacement resorption (ankylosis). Based on the authors’ clinical experience, ankylosis is the most serious complication after autotransplantation of developing premolars to the anterior maxilla. In case of complications, alternative solutions may include transplantation of another developing premolar (second transplantation), or orthodontic mesialization of the neighboring lateral incisor after extraction of the failed transplant (Fig. 1G-I).10 If a contralateral premolar is anyhow scheduled for extraction in
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order to achieve dental arch symmetry, it can then serve as a suitable donor for a second transplantation. Consequently, it is very important to carefully monitor transplanted teeth after surgery, because early detection of complications usually provides a better chance for a second transplantation (Fig. 1G-I). Preservation of an ankylosed transplant in the anterior maxilla in young children is usually not advisable, because of the unpredictable long-term prognosis and impaired smile esthetics.
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development can affect the development of their hard tissues. If premolars are transplanted during later stages of their root formation (about 3/4 of the final root length), it is usually recommended to wait 3-6 months after surgery to ascertain undisturbed healing.28 On the other hand, orthodontic mobilization shortly after transplantation (at about six weeks) was reported to decrease the risk for ankylosis after transplantation of more mature teeth.
Orthodontic repositioning for optimal reshaping Post-surgical orthodontics Most patients who have undergone autotransplantation of developing premolars to replace missing maxillary incisors need orthodontic treatment after surgery in order to: - close the space in the dental arch after removal of the donor premolar, - align the transplanted premolar in the dental arch, - level the gingival margins, - position the transplant for optimal reshaping to mimick the morphology of a natural incisor, or - correct a concomitant malocclusion. If the selection of a donor premolar is predominantly based on the optimal stage of root development rather than on orthodontic indications, anchorage control must be supplemented. TADs or Herbst-type Class II correctors may be helpful to assist planned tooth movements (Fig. 2). Alternative treatment options after removal of a donor premolar usually include prosthodontic substitution of the donor tooth with either partial fixed dentures (PFD) or dental implants after the end of growth.7,8 Transplantation of developing wisdom teeth constitutes another good option which may be performed before the cessation of growth depending on their root development. Orthodontic alignment of the transplanted premolar should preferably start after completion of the post-surgical healing phase. If donor premolars were transplanted at the earlier stages of root development, it is necessary to wait until root development reaches at least 3/4 of the final root length. Orthodontic repositioning of transplanted premolars at earlier stages of root
Orthodontic repositioning of the transplanted premolar after surgery significantly improves the esthetic outcome and should be recommended to the patient and parents/caregivers before surgery.11 Orthodontic repositioning of the transplanted premolar usually includes tooth alignment and levelling of the gingival margin between the transplanted premolar and the neighboring teeth, and should be performed using light forces, considering the transplant a traumatized tooth. It is often better to reshape the transplanted premolar before orthodontic repositioning, if the position of the transplant and its long axis need to be adjusted to the neighboring incisors. Sometimes, extra space is needed to match the width of the transplant with the natural central incisor. In this case, it is necessary to bond a premolar bracket on the unrestored transplanted premolar, and to open an adequate space for its reshaping (Figs. 1J, 2K). The optimal position of the zenith should be defined and respected. After the adequate space for reshaping is achieved, the premolar bracket is removed, and the morphology of the transplanted premolar is adapted to that of the central incisor using indirect or direct techniques. If further orthodontic repositioning of the reshaped transplant is necessary, a corresponding central incisor bracket is bonded, and the orthodontic treatment is continued until satisfactory alignment is obtained (Figs. 1K, 2L). It is usually easier to perform a good direct composite restoration of the transplanted premolar, if some mesial and distal space excess has been created (Fig. 1J-K). The palatal cusp of the transplanted premolar does not require grinding, because occlusal interferences can be avoided by palatally directed orthodontic tooth movement (Fig. 2K).
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Reshaping transplanted premolars in the anterior maxilla Transplanted teeth replacing traumatically lost maxillary incisors should not only have a good potential for successful healing, but also a favorable tooth form to match incisor morphology, as these teeth are placed in the center of the esthetic zone. Premolars have a comparable morphology to the width of maxillary
central incisors, which have the highest incidence of traumatic loss. A matching cervical width of the transplant and the lost incisor is critical, as only limited preparation of the transplant is possible during restorative treatment. Third molars, which are often considered as donor teeth, are mostly unsuitable for reshaping to maxillary incisors.29 Occasionally, supernumerary lateral incisors can be transplanted to the anterior maxilla.9
Figure 4. The maxillary right second premolar was transplanted to replace the traumatically injured maxillary left central incisor in a 9-years old girl (A). The transplanted premolar was reshaped to the incisor morphology with a direct composite build-up and orthodontic treatment was performed in order to align the transplanted tooth and to obtain normal occlusal relations (B). Four years after transplantation, the composite restoration was replaced by a feldspatic porcelain veneer to improve dental esthetics (C). The patient was satisfied with her smile after placement of the veneer (D).
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Contemporary techniques for reshaping autotransplanted premolars include the use of direct and indirect composite restorations or porcelain laminate veneers (PLV) (Figs. 1, 2, 4). The bonded restoration should not include any dentine preparation, because the presence of tertiary dentine in transplanted developing teeth may lead to different types of root pathology. Preferably, enamel reduction should also be avoided (Fig. 1J-L). Extensive grinding of premolars can interfere with pulp healing after surgery.28 If unerupted donor premolars are transplanted, they are usually placed under the gingiva or at the gingival level. It must be acknowledged that transplanted teeth should continue their root development and erupt similarly to normal developing teeth, hence the final restoration should only be placed after their full eruption. Post-surgical root development of a transplanted premolar depends on the initial stage of its root development upon surgery and may take more than two years in less mature premolars. Careful monitoring of the transplanted tooth by clinical inspection, and evaluation of a good quality intraoral radiograph of both the transplant and the control contralateral tooth, if present, is mandatory. Most frequently, the transplanted premolars are initially restored with composite material, and later receive PLVs (Fig. 4B-C). The introduction of 3-D technologies offers new options for fabrication of printed indirect restorations, which can be bonded on the transplanted teeth. PVLs offer the best biologic compatibility and esthetics and are thus recommended as “gold standard” procedure. Feldspathic PLVs are particularly indicated for minimally invasive reduction of hard tissues and good biomechanical properties (Fig. 4C-D).
Conclusions Autotransplanation of developing premolars is a viable treatment option for replacing missing maxillary central incisors in children and adolescents. It is necessary to evaluate the orthodontic indications for premolar removal and to match the morphology of the donor and the recipient site using CBCT assessment before treatment. Surgical damage to the root surface of the transplanted premolar must be avoided, and presurgical orthodontic space opening is frequently
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necessary. After surgery, healing and root development of the transplanted teeth requires periodic monitoring in order to detect early signs of failure. Post-surgical orthodontic repositioning of the transplanted premolar and reshaping or restoring them to incisor morphology is often indicated to ensure the best esthetic treatment result. Close interdisciplinary cooperation is imperative for achieving a successful long-term outcome.
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15. Czochrowska EM, Plakwicz P, Stenvik A. Dentoalveol€ares Wachstum beim Fehlen von Z€ahnen: Autotransplantation von wurzelunreifen Z€ahnen, kieferorthop€adischer L€ uckenschluss oder Implantatversorgung? Informationen aus Orthodontie & Kieferorthop€ a die. 2010;2:105–112. 16. Kristerson L. Autotransplantation of human premolars. A clinical and radiographic study of 100 teeth. Int J Oral Surg. 1985;14:200–213. 17. Andreasen JO, Paulsen HU, Yu Z, et al. A long-term study of 370 autotransplanted premolars. Part IV. Root development subsequent to transplantation. Eur J Orthod. 1990;12(1):38–50. 18. Stenvik A, Zachrisson BU. Orthodontic closure and transplantation in the treatment of missing anterior teeth. An overview. Endod Dent Traumatol. 1993;9:45–52. 19. Andreasen JO, Paulsen HU, Yu Z, Bayer T, Schwartz O. A long-term study of 370 autotransplanted premolars. Part II. Tooth survival and pulp healing subsequent to transplantation. Eur J Orthod. 1990;12(1):14–24. 20. Andreasen JO, Paulsen HU, Yu Z, Schwartz O. A longterm study of 370 autotransplanted premolars. Part III. Periodontal healing subsequent to transplantation. Eur J Orthod. 1990;12(1):25–37. 21. Jakobsen C, Stokbro K, Kier-Swiatecka E, et al. Autotransplantation of premolars: does surgeon experience matter? Int J Oral Maxillofac Surg. 2018;47(12):1604–1608. 22. Kristerson L, Andreasen JO. The effect of splinting upon periodontal and pulpal healing after autotransplanation of mature and immature permanent incisors in monkeys. Int J Oral Surg. 1983;12(4):239–249.
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