- Email: [email protected]
Vertical bone augmentation for implant site development: A burgeoning role for orthodontics
Vertical bone augmentation for implant site development: A burgeoning role for orthodontics Tarek Elshebiny, Juan Martin Palomo, Ernest Erian, Sebastian Baumgaertel, and Leena Palomo Extraction of an ankylosed tooth is a common scenario orthodontists face in daily practice. The extraction of an ankylosed tooth is often traumatic, leaving behind a defective alveolar ridge. A common approach to correct alveolar bony defects is bone grafting periodontal surgeries. This article shows a less invasive biological method by bodily horizontal tooth movement into the edentulous defect to build a wide bony ridge. (Semin Orthod 2019; 25:158– 164) © 2019 Elsevier Inc. All rights reserved.
Introduction
R
estoring esthetics, comfort and function when teeth are missing is one of the most common problems dental teams face in daily practice. Teeth may be missing for several reasons; including trauma, caries, periodontal disease, ankylosed teeth which fail to erupt, orthodontic extractions and congenitally missing teeth. Treatment options were enhanced when implants became more accessible.1 3 The dimensions of the alveolar ridge are critically significant for implant outcome. The importance of the vertical ridge height is intuitive in that vertical confers implant stability needed for initial rigid fixation and primary stability needed for osseointegration. The importance of the horizontal dimensions are less obvious, but have been well elucidated in the literature. Greater than 2 mm of bone buccal to the planned implant confers long term confidence in the stability of the gingival margin such that the margin
Department of Orthodontics, School of Dental Medicine, Case Western Reserve University, Cleveland, OH, United States; Department of Orthodontics, Case Western Reserve University, Cleveland, OH, United States; Craniofacial Imaging Center, School of Dental Medicine, Case Western Reserve University, Cleveland, OH, United States; School of Dental Medicine, Case Western Reserve University, Cleveland, OH, United States. Corresponding author at: Case Western Reserve University, School of Dental Medicine, Department of Orthodontics, 2124 Cornell Rd., Cleveland, OH 44106, United States. E-mail: [email protected] © 2019 Elsevier Inc. All rights reserved. 1073-8746/12/1801-$30.00/0 https://doi.org/10.1053/j.sodo.2019.05.008
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would remain intact rather than recede from the implant, abutment, and crown interface. Unfortunately it is common that the alveolar ridge presents with deformities.4 7 stemming from tooth extraction, or extracted teeth that are not promptly replaced.6,7 The stages of ridge resorption after tooth extraction have been well described in the literature.8 10 When alveolar bone is deficient site development is indicated prior to implant therapy. Bone augmentation for its correction can be achieved using various surgical techniques including guided bone regeneration, block grafts, and ridge expansion techniques.4 7 Horizontal bone augmentation continues to be more predictable, especially with the technologic developments in tissue engineering. In spite of the multiple surgical methods, gaining vertical bone height remains a surgical challenge.8 The burgeoning role for orthodontics in sophisticated cases in need of implant site development started with forced eruption as more predictable option for vertical bone augmentation.9,10 The bone adaptive response was elucidated when forced eruption was identified by multidisciplinary teams as a means to address the problems with vertical ridge defects.11 On the other hand, moving a tooth mesiodistally along the ridge is a much more novel means for implant site development. Hom and Turley in the mid 80’s, while closing spaces of missing permanent molars, noticed an increase in the alveolar ridge width. They mention how there is little information regarding orthodontic closure in remodeled or edentulous areas, and the
Seminars in Orthodontics, Vol 25, No 2, 2019: pp 158 164
Vertical bone augmentation for implant site development: A burgeoning role for orthodontics
periodontal benefits that orthodontic movement may bring to such a case.[4] Classically, such horizontal tooth movement was cumbersome as compared to forced eruption. However, with the advent of TADs horizontal tooth movement can be explored for implant site development using the same adaptive bone response as a strategy to target defects. The following clinical case shows an adolescent patient who had a severe alveolar ridge defect after traumatic extraction of an ankylosed maxillary second premolar. An orthodontic approach, enhanced with TADs, was used to create more ideal ridge architecture by moving the first premolar distally to the second premolar position. As a result, a more appropriate alveolar ridge is available for the dental implant.
Case description A 17.5 year-old girl was referred to the Case Western Reserve University orthodontic department for comprehensive orthodontic treatment. Patient and parents chief complaint was the impacted right maxillary second premolar. Intraoral examination revealed a missing maxillary right second premolar. The panoramic radiograph constructed from cone beam computed tomography (CBCT) showed a retained but submerged maxillary right deciduous second molar, impacted maxillary right second premolar, mesially tipped maxillary right first molar and distally tipped maxillary right first premolar (Fig 1). At initial presentation, complete periodontal evaluation was completed. The first molar and the erupted premolar probed 2 3 mm and there was no bleeding on probing or any clinical signs of inflammation to the area. The gingiva presented with thick biotype, and the area was deemed healthy for further treatment. In consideration of the patient’s age and goals, initial treatment objectives were to create
Figure 1. Panoramic x-ray showing the retained deciduous molar and the impacted maxillary second premolar on the right side.
159
space for guided eruption of the impacted premolar and establish proper occlusion on both sides. Patient was referred for extraction of the retained maxillary primary second molar and placement of a gold chain attachment on the impacted premolar to start bringing it into occlusion using a closed eruption technique (Fig. 2). Sliding mechanics were used to open a space between first molar and premolar. Once space was opened, power thread was attached to the gold chain to start guided eruption of the impacted second premolar. After 6 months of orthodontic traction, a progress panoramic radiograph was taken to assess the position of the impacted premolar which did not show any movement towards the occlusal plane. The tooth was deemed ankylosed and it was decided that further attempts to move it could lead to reciprocal, undesired intrusion of the adjacent maxillary teeth. The patient was sent to her oral surgeon for extraction and possible implant replacement. Five weeks after the extraction, the patient presented to her orthodontic appointment with a large combination ridge defect, both vertical and horizontal in dimension, in the area of the second premolar. Although the biotype remained thick, the interdental col had an overly exaggerated saddle shape (Fig. 3). Furthermore, just to address the significant vertical and horizontal ridge deficiencies multiple surgical bone augmentation procedures would be necessary. And even with such intensive surgery, obtaining significant gains specifically the vertical component of the deficiency has a poor surgical prognosis. This left little promise of ever having an esthetic papilla mesial to the molar.12,13 Given that information, alternative treatment options for implant site development were presented to the patient that included, multiple bone augmentation surgical procedures, and orthodontic tooth movement through the defective ridge. The orthodontic option was chosen. with the plan of retracting the first premolar in place of the extracted second premolar, such that the predictable biologic bone response would be to “bring” the alveolar housing round the first premolar into the deficient second premolar site. This would leave behind a morphologically compatible alveolar for a first premolar dental implant and create bone in the along the ridge to the newly distalized first premolar in the second premolar site. In order to prevent any anchorage loss, a temporary
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Figure 2. (A) Small field of view CBCT showing the traction of the impacted second premolar. (B) Clinical photograph showing the traction of the impacted second premolar using a gold chain.
anchorage device (TAD) was placed in the palatal alveolar process, connected to the first molar using a stainless steel wire to provide indirect anchorage, locking-in the first molar while retracting the first
premolar. Palatal buttons were bonded to both the first molar and first premolar to control for rotation during retraction (Fig. 4).14 Light continious force (50 g) was used for retraction for 10 months.
Vertical bone augmentation for implant site development: A burgeoning role for orthodontics
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Figure 3. A small field of view CBCT showing the alveolar bony defect after extraction of the ankylosed second premolar.
Figure 4. (A) A small field of view CBCT showing the TAD placed in the palatal alveolar process. (B) Clinical photograph showing the TAD placed in the palate and connected to the first molar through a wire to provide anchorage needed for retraction of the first premolar.
Retraction was performed on a rectangular stainless steel wire (0.017 £ 0.025 ss). The rate of tooth movement was approximately 0.8 mm per month. After 8 months of retraction, a progress small field of view CBCT was taken to visualize bone formed in three dimensions. Periodontal health continued to be excellent, with no bleeding on probing or other signs of inflammation in the quadrant. Plaque control continued to be excellent. All six sites around the molar and premolar probed 3 mm or less. Greater than 2 mm keratinized tissue was identified on all sites. Recession was present, <2 mm on the mesial of the molar, conferring a stage I
periodontitis classification. Clinically healthy periodontal presentation of area allowed for mucoperiosteal flap elevation. The vitally important dimensions of the regenerated alveolar ridge was confirmed when the flap was elevated. With ridge morphology such that two mm are available buccal to the planned implant, confers confidence in stability buccal bone scalloped architecture, interdental festooning, and the long term soft tissue margin. Complete retraction of the first premolar was achieved 2 months after the progress CBCT (Fig. 5). Furthermore, distal root movement of the retracted premolar was attempted, but the
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Figure 5. (A) Mucoperiosteal flap confirming alveolar ridge thickness. (B) A small field of view CBCT showing the bone deposition during retraction of the first premolar. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Figure 6. (A) Panoramic x-ray showing the implant placed in the first premolar site. (B) Periapical x-ray showing the implant placed in the first premolar site. (C) Occlusal view of implant in newly formed ridge. (D) Temporary restoration in place to hold space created.
dilacerations of the roots have interfered. The resulting space showed a broad alveolar ridge, suitable for dental implant placement. Fig. 6 shows radiographically the subsequently inserted implant and Fig. 7 shows from an occlusal view, the retraction from initial to implant placement. The orthodontic ridge augmentation allowed for a standard implant insertion. A surgical stent that indicated the ideal prosthetic position was
used, an implant osteotomy was completed, and a 4.1 mm by 10 mm implant was placed with 35 Ncm insertion torque at the level of bone crest achieving primary stability . Occlusal surface was reduced to bring the implant out of contact. To increase the zone of keratinized gingiva and to increase the chances of obtaining a natural looking papilla, a sub-epithelial connective tissue graft was harvested from the palate and slid under the buccal flap and secured with 5.0 chromic-gut suture. Interproximal sutures were used to close flap. A temporary abutment and a prefabricated acrylic tooth were used to fabricate a temporary prosthesis to further shape the gingival papilla.
Discussion Alveolar bony defects are common situations that an orthodontist may encounter in clinical practice. For the clinical case reported here, a severe vertical and horizontal alveolar bony defect resulted from traumatic extraction of an ankylosed maxillary second premolar. Since the prognosis of surgical vertical augmentation remains poor, the bone ridge was augmented by retracting a tooth with appropriate periodontal attachment into the bony defect, leaving behind an implant site where the tooth previously resided. The distalized first premolar brought its periodontal attachment to its new location in the second premolar site due to a predictable bone biologic response to orthodontic tooth movement. Although there are usually multiple options to any problem in dentistry, advantages and disadvantages of different approaches have to be evaluated by the treating clinicians, preferably in a team approach when it comes to interdisciplinary work. The method explained in this article offers a biologic method for ridge augmentation by slow bodily movement of the first premolar into the edentulous area of the second premolar. A site free of periodontal inflammation is the keystone to explaining the bone adaptive response. The first molar and premolar teeth involved were free of bleeding on probing, the key indicator of inflammation, from the initial presentation, through the tooth movement phase and through the final crown placement. Classic literature spells out that had the site been inflamed, presented with bleeding, had a shift in color from pale pink to red, or had the characteristic puffy gingival and rolled gingival margins, the stability of the clinical periodontal attachment during tooth movement would
Vertical bone augmentation for implant site development: A burgeoning role for orthodontics
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Figure 7. Occlusal view showing the retraction throughout treatment. (A) Initial, (B) 8 months after starting retraction. (C) 10 months after starting retraction, showing complete retraction. (D) Date of removal of orthodontic appliances, showing a dental implant already in place.
not have allowed for such an outcome. Attia et al. showed that orthodontic regenerative for bone formation therapy showed more gain in clinical attachment level when compared to periodontal regenerative surgeries. The bone formation is successful when the tooth that is moved through the bone has and maintains proper gingival attachment. The attachment level and periodontal health is directly related to the successful outcome, and should be used when selecting which tooth will be moved.15 In a site free of inflammation, this type of horizontal tooth movement will trigger bone deposition on the tension side and gradually build a wide bony ridge for suitable for implant placement. The vital importance of a site free of inflammation lies in the bone remodeling biology of tooth movement. Orthodontic tooth movement is a controlled use of tension to guide bone remodeling through osteoblasts and pressure through osteoclasts. This respective bone deposition and resorption, occurs through the RANKL pathway such that bone cells are signaled and activated. The RANKL pathway signaling molecules are inflammatory cytokines, IL1, IL6, and TNFalpha; these are the same inflammatory mediators which are overproduced when local
inflammation is present. When inflammation is present the over abundance of these signaling molecules creates bone loss around teeth, as is the case in periodontitis. When inflammation is absent these cytokines can be modulated through force and pressure to deposite bone such that the teeth retain their periodontal attachment apparatus as they are moved orthodontically.16 18 Such a biologic approach has several advantages over the gold standard, which is autogenous bone grafts taken from the maxillary tuberosity, the ramus, the symphysis, or the mandibular retro molar area.19 As is reported in the literature, soft tissue changes associated with orthodontic movement were not predictable, regardless of the direction of tooth movement.20 On the other hand, a dimished stability of the soft tissue is also not expected, because the periodontium was free of inflammation. Maintaining an interdental papilla in augmented sites continues to be a challenge. However, there is no data to suggest a rate of extrusion which effectively creates enough bone to create a papilla.21,22 In this novel case, moving the tooth horizontally maintained bone height such that when the crown was placed, there was
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less than 5 mm from the bone crest to the contact point. This 5 mm benchmark is considered appropriate to expect papilla formation. Unlike orthodontic extrusion, the mucogingival junction did not move occlusally with tooth movement. However the cleft of bone distal to the premolar was not addressed. In this case, due to the periodontally healthy conditions, thick biotype and good hygiene no further grafting was indicated. However if the patient was susceptible to attachment loss around the molar, orthodontic extrusion of the premolar to correct the defect between molar and premolar would have been indicated. Their observations agree with ours. We may go a step further and suggest that orthodontic tooth movement for implant site development and alveolar ridge development should be considered an alternative treatment option.
7.
8.
9.
10.
11.
12.
Conclusion The present article shows a case where horizontal orthodontic tooth movement was used to augment a horizontally and vertically deficient alveolar ridge. Although ridge augmentation in the form of forced eruption was identified decades ago, horizontal tooth movement is also available as a modality as orthodontics enhances the restoration of missing teeth with dental implants. Orthodontic movement is a viable option for alveolar ridge development, but proper case selection, which includes attachment level, is crucial for the outcome success.
13.
References
17.
1. Lindskog-Stokland B, Hansen K, Ekestubbe A, et al. Orthodontic tooth movement into edentulous ridge areas a case series. Eur J Orthod. 2013;35(3):277–285. 2. Spear FM, Mathews DM, Kokich VG. Interdisciplinary management of single-tooth implants. Semin Orthod. 1997;3(1):45–72. 3. Zachrisson BU. Bjorn U. Zachrisson, DDS, MSD, PhD, on current trends in adult treatment, part 2. Interview by Robert G. Keim. J Clin Orthod. 2005;39(5):285–296. quiz 315. 4. Carlsson GE, Bergman B, Hedegard B. Changes in contour of the maxillary alveolar process under immediate dentures. A longitudinal clinical and x-ray cephalometric study covering 5 years. Acta Odontol Scand. 1967;25(1):45–75. 5. Kim SJ, Kim JW, Choi TH, Lee KJ. Restoration of a vertical alveolar bone defect by orthodontic relocation of a mesially impacted mandibular first molar. Am J Orthod Dentofacial Orthop. 2015;147(4 Suppl):S122–S132. 6. Lee KJ, Joo E, Yu HS. Restoration of an alveolar bone defect caused by an ankylosed mandibular molar by root
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movement of the adjacent tooth with miniscrew implants. Am J Orthod Dentofacial Orthop. 2009;136(3):440–449. Thilander B, Odman J, Lekholm U. Orthodontic aspects of the use of oral implants in adolescents: a 10-year follow-up study. Eur J Orthod. 2001;23(6):715–731. Tonetti MS, Hammerle CH, the European Workshop on Periodontology Group C. Advances in bone augmentation to enable dental Impmplant Placement: consensus Report of the Sixth European Workshop on Periodontology. J Clin Periodontol. 2008;35:168–172. Potashnick SR, Rosenberg ES. Forced eruption: principles in periodontics and restoarive dentistry. J Prosthet Dent. 1982;48(141):312. 13. Brindis MA, Block MS. Orthodontic tooth extrusion to enhance soft tissue implant esthetics. J Oral Maxillofac Surg. 2009;67(11 Suppl):49–59. Salama H, Salama M. The role of orthodontic extrusive remodeling in the enhancement of soft and hard tissue profiles prior to implant placement: a systematic approach to the management of extraction site defects. Int J Periodontics Restor Dent. 1993. Wada Y, Yoshimura H, Mikami I, Matsuzawa K, Mizuno M. Implant site development by horizontal tooth movement to an esthetic area: a case report. Int J Periodontics Rest Dent. 2015;35(5):697–705. Saletta JM, Garcia JJ, Carames JMM, Schliephake H, da Silva Marques DN. Quality assessment of systematic reviews on vertical bone regeneration. Int J Oral Maxillofac Surg. 2018;48:364–372. https://doi.org/10.1016/ j.ijom.2018.07.014. [Epub ahead of print]. Baumgaertel S. Cortical bone thickness and bone depth of the posterior palatal alveolar process for mini-implant insertion in adults. Am J Orthod Dentofacial Orthop. 2011;140 (6):806–811. Attia MS, Shoreibah EA, Ibrahim SA. Regenerative therapy of osseous defects combined with orthodontic tooth movement. J Int Acad Periodontol. 2012;14(1):17–25. Huang H, Williams RC, Kyrkanides S. Accelerated orthodontic tooth movement: molecular mechanisms. Am J Orthod Dentofacial Orthop. 2014;146:620–632. Graber LW, Vanarsdall RL, Vig KWL. Orthodontics: Current Principles and Techniques. 5th ed. Philadelphia, PA: Elsevier/Mosby. Nogueira AVB, de Molon RS, Nokhbehsaim M, Deschner J, Cirelli JA. Contribution of biomechanical forces to inflammation-induced bone resorption. J Clin Periodontol. 2017;44:31–41. de A TSR, Moura AP, Andrade I, et al. Experimental model of tooth movement in mice: a standardized protocol for studying bone remodeling under compression and tensile strains. J Biomech. 2012;45:2729–2735. Wang HL, Al-Shammari K. HVC ridge deficiency classification: a therapeutically oriented classification. Int J Periodontics Restor Dent. 2002;22(4):335–343. Amato F, Mirabella AD, Macca U, Tarnow DP. Implant site development by orthodontic forced extraction: a preliminary study. Int J Oral Max Implants. 2012; 27:411–420. Keceli HG, Guncu MB, Atalay Z, Evginger MS. Forced eruption and implant site development in the esthetic zone: a case report. Eur J Dent. 2014;8(2):269–275.
Introduction
R
estoring esthetics, comfort and function when teeth are missing is one of the most common problems dental teams face in daily practice. Teeth may be missing for several reasons; including trauma, caries, periodontal disease, ankylosed teeth which fail to erupt, orthodontic extractions and congenitally missing teeth. Treatment options were enhanced when implants became more accessible.1 3 The dimensions of the alveolar ridge are critically significant for implant outcome. The importance of the vertical ridge height is intuitive in that vertical confers implant stability needed for initial rigid fixation and primary stability needed for osseointegration. The importance of the horizontal dimensions are less obvious, but have been well elucidated in the literature. Greater than 2 mm of bone buccal to the planned implant confers long term confidence in the stability of the gingival margin such that the margin
Department of Orthodontics, School of Dental Medicine, Case Western Reserve University, Cleveland, OH, United States; Department of Orthodontics, Case Western Reserve University, Cleveland, OH, United States; Craniofacial Imaging Center, School of Dental Medicine, Case Western Reserve University, Cleveland, OH, United States; School of Dental Medicine, Case Western Reserve University, Cleveland, OH, United States. Corresponding author at: Case Western Reserve University, School of Dental Medicine, Department of Orthodontics, 2124 Cornell Rd., Cleveland, OH 44106, United States. E-mail: [email protected] © 2019 Elsevier Inc. All rights reserved. 1073-8746/12/1801-$30.00/0 https://doi.org/10.1053/j.sodo.2019.05.008
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would remain intact rather than recede from the implant, abutment, and crown interface. Unfortunately it is common that the alveolar ridge presents with deformities.4 7 stemming from tooth extraction, or extracted teeth that are not promptly replaced.6,7 The stages of ridge resorption after tooth extraction have been well described in the literature.8 10 When alveolar bone is deficient site development is indicated prior to implant therapy. Bone augmentation for its correction can be achieved using various surgical techniques including guided bone regeneration, block grafts, and ridge expansion techniques.4 7 Horizontal bone augmentation continues to be more predictable, especially with the technologic developments in tissue engineering. In spite of the multiple surgical methods, gaining vertical bone height remains a surgical challenge.8 The burgeoning role for orthodontics in sophisticated cases in need of implant site development started with forced eruption as more predictable option for vertical bone augmentation.9,10 The bone adaptive response was elucidated when forced eruption was identified by multidisciplinary teams as a means to address the problems with vertical ridge defects.11 On the other hand, moving a tooth mesiodistally along the ridge is a much more novel means for implant site development. Hom and Turley in the mid 80’s, while closing spaces of missing permanent molars, noticed an increase in the alveolar ridge width. They mention how there is little information regarding orthodontic closure in remodeled or edentulous areas, and the
Seminars in Orthodontics, Vol 25, No 2, 2019: pp 158 164
Vertical bone augmentation for implant site development: A burgeoning role for orthodontics
periodontal benefits that orthodontic movement may bring to such a case.[4] Classically, such horizontal tooth movement was cumbersome as compared to forced eruption. However, with the advent of TADs horizontal tooth movement can be explored for implant site development using the same adaptive bone response as a strategy to target defects. The following clinical case shows an adolescent patient who had a severe alveolar ridge defect after traumatic extraction of an ankylosed maxillary second premolar. An orthodontic approach, enhanced with TADs, was used to create more ideal ridge architecture by moving the first premolar distally to the second premolar position. As a result, a more appropriate alveolar ridge is available for the dental implant.
Case description A 17.5 year-old girl was referred to the Case Western Reserve University orthodontic department for comprehensive orthodontic treatment. Patient and parents chief complaint was the impacted right maxillary second premolar. Intraoral examination revealed a missing maxillary right second premolar. The panoramic radiograph constructed from cone beam computed tomography (CBCT) showed a retained but submerged maxillary right deciduous second molar, impacted maxillary right second premolar, mesially tipped maxillary right first molar and distally tipped maxillary right first premolar (Fig 1). At initial presentation, complete periodontal evaluation was completed. The first molar and the erupted premolar probed 2 3 mm and there was no bleeding on probing or any clinical signs of inflammation to the area. The gingiva presented with thick biotype, and the area was deemed healthy for further treatment. In consideration of the patient’s age and goals, initial treatment objectives were to create
Figure 1. Panoramic x-ray showing the retained deciduous molar and the impacted maxillary second premolar on the right side.
159
space for guided eruption of the impacted premolar and establish proper occlusion on both sides. Patient was referred for extraction of the retained maxillary primary second molar and placement of a gold chain attachment on the impacted premolar to start bringing it into occlusion using a closed eruption technique (Fig. 2). Sliding mechanics were used to open a space between first molar and premolar. Once space was opened, power thread was attached to the gold chain to start guided eruption of the impacted second premolar. After 6 months of orthodontic traction, a progress panoramic radiograph was taken to assess the position of the impacted premolar which did not show any movement towards the occlusal plane. The tooth was deemed ankylosed and it was decided that further attempts to move it could lead to reciprocal, undesired intrusion of the adjacent maxillary teeth. The patient was sent to her oral surgeon for extraction and possible implant replacement. Five weeks after the extraction, the patient presented to her orthodontic appointment with a large combination ridge defect, both vertical and horizontal in dimension, in the area of the second premolar. Although the biotype remained thick, the interdental col had an overly exaggerated saddle shape (Fig. 3). Furthermore, just to address the significant vertical and horizontal ridge deficiencies multiple surgical bone augmentation procedures would be necessary. And even with such intensive surgery, obtaining significant gains specifically the vertical component of the deficiency has a poor surgical prognosis. This left little promise of ever having an esthetic papilla mesial to the molar.12,13 Given that information, alternative treatment options for implant site development were presented to the patient that included, multiple bone augmentation surgical procedures, and orthodontic tooth movement through the defective ridge. The orthodontic option was chosen. with the plan of retracting the first premolar in place of the extracted second premolar, such that the predictable biologic bone response would be to “bring” the alveolar housing round the first premolar into the deficient second premolar site. This would leave behind a morphologically compatible alveolar for a first premolar dental implant and create bone in the along the ridge to the newly distalized first premolar in the second premolar site. In order to prevent any anchorage loss, a temporary
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Figure 2. (A) Small field of view CBCT showing the traction of the impacted second premolar. (B) Clinical photograph showing the traction of the impacted second premolar using a gold chain.
anchorage device (TAD) was placed in the palatal alveolar process, connected to the first molar using a stainless steel wire to provide indirect anchorage, locking-in the first molar while retracting the first
premolar. Palatal buttons were bonded to both the first molar and first premolar to control for rotation during retraction (Fig. 4).14 Light continious force (50 g) was used for retraction for 10 months.
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Figure 3. A small field of view CBCT showing the alveolar bony defect after extraction of the ankylosed second premolar.
Figure 4. (A) A small field of view CBCT showing the TAD placed in the palatal alveolar process. (B) Clinical photograph showing the TAD placed in the palate and connected to the first molar through a wire to provide anchorage needed for retraction of the first premolar.
Retraction was performed on a rectangular stainless steel wire (0.017 £ 0.025 ss). The rate of tooth movement was approximately 0.8 mm per month. After 8 months of retraction, a progress small field of view CBCT was taken to visualize bone formed in three dimensions. Periodontal health continued to be excellent, with no bleeding on probing or other signs of inflammation in the quadrant. Plaque control continued to be excellent. All six sites around the molar and premolar probed 3 mm or less. Greater than 2 mm keratinized tissue was identified on all sites. Recession was present, <2 mm on the mesial of the molar, conferring a stage I
periodontitis classification. Clinically healthy periodontal presentation of area allowed for mucoperiosteal flap elevation. The vitally important dimensions of the regenerated alveolar ridge was confirmed when the flap was elevated. With ridge morphology such that two mm are available buccal to the planned implant, confers confidence in stability buccal bone scalloped architecture, interdental festooning, and the long term soft tissue margin. Complete retraction of the first premolar was achieved 2 months after the progress CBCT (Fig. 5). Furthermore, distal root movement of the retracted premolar was attempted, but the
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Figure 5. (A) Mucoperiosteal flap confirming alveolar ridge thickness. (B) A small field of view CBCT showing the bone deposition during retraction of the first premolar. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Figure 6. (A) Panoramic x-ray showing the implant placed in the first premolar site. (B) Periapical x-ray showing the implant placed in the first premolar site. (C) Occlusal view of implant in newly formed ridge. (D) Temporary restoration in place to hold space created.
dilacerations of the roots have interfered. The resulting space showed a broad alveolar ridge, suitable for dental implant placement. Fig. 6 shows radiographically the subsequently inserted implant and Fig. 7 shows from an occlusal view, the retraction from initial to implant placement. The orthodontic ridge augmentation allowed for a standard implant insertion. A surgical stent that indicated the ideal prosthetic position was
used, an implant osteotomy was completed, and a 4.1 mm by 10 mm implant was placed with 35 Ncm insertion torque at the level of bone crest achieving primary stability . Occlusal surface was reduced to bring the implant out of contact. To increase the zone of keratinized gingiva and to increase the chances of obtaining a natural looking papilla, a sub-epithelial connective tissue graft was harvested from the palate and slid under the buccal flap and secured with 5.0 chromic-gut suture. Interproximal sutures were used to close flap. A temporary abutment and a prefabricated acrylic tooth were used to fabricate a temporary prosthesis to further shape the gingival papilla.
Discussion Alveolar bony defects are common situations that an orthodontist may encounter in clinical practice. For the clinical case reported here, a severe vertical and horizontal alveolar bony defect resulted from traumatic extraction of an ankylosed maxillary second premolar. Since the prognosis of surgical vertical augmentation remains poor, the bone ridge was augmented by retracting a tooth with appropriate periodontal attachment into the bony defect, leaving behind an implant site where the tooth previously resided. The distalized first premolar brought its periodontal attachment to its new location in the second premolar site due to a predictable bone biologic response to orthodontic tooth movement. Although there are usually multiple options to any problem in dentistry, advantages and disadvantages of different approaches have to be evaluated by the treating clinicians, preferably in a team approach when it comes to interdisciplinary work. The method explained in this article offers a biologic method for ridge augmentation by slow bodily movement of the first premolar into the edentulous area of the second premolar. A site free of periodontal inflammation is the keystone to explaining the bone adaptive response. The first molar and premolar teeth involved were free of bleeding on probing, the key indicator of inflammation, from the initial presentation, through the tooth movement phase and through the final crown placement. Classic literature spells out that had the site been inflamed, presented with bleeding, had a shift in color from pale pink to red, or had the characteristic puffy gingival and rolled gingival margins, the stability of the clinical periodontal attachment during tooth movement would
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Figure 7. Occlusal view showing the retraction throughout treatment. (A) Initial, (B) 8 months after starting retraction. (C) 10 months after starting retraction, showing complete retraction. (D) Date of removal of orthodontic appliances, showing a dental implant already in place.
not have allowed for such an outcome. Attia et al. showed that orthodontic regenerative for bone formation therapy showed more gain in clinical attachment level when compared to periodontal regenerative surgeries. The bone formation is successful when the tooth that is moved through the bone has and maintains proper gingival attachment. The attachment level and periodontal health is directly related to the successful outcome, and should be used when selecting which tooth will be moved.15 In a site free of inflammation, this type of horizontal tooth movement will trigger bone deposition on the tension side and gradually build a wide bony ridge for suitable for implant placement. The vital importance of a site free of inflammation lies in the bone remodeling biology of tooth movement. Orthodontic tooth movement is a controlled use of tension to guide bone remodeling through osteoblasts and pressure through osteoclasts. This respective bone deposition and resorption, occurs through the RANKL pathway such that bone cells are signaled and activated. The RANKL pathway signaling molecules are inflammatory cytokines, IL1, IL6, and TNFalpha; these are the same inflammatory mediators which are overproduced when local
inflammation is present. When inflammation is present the over abundance of these signaling molecules creates bone loss around teeth, as is the case in periodontitis. When inflammation is absent these cytokines can be modulated through force and pressure to deposite bone such that the teeth retain their periodontal attachment apparatus as they are moved orthodontically.16 18 Such a biologic approach has several advantages over the gold standard, which is autogenous bone grafts taken from the maxillary tuberosity, the ramus, the symphysis, or the mandibular retro molar area.19 As is reported in the literature, soft tissue changes associated with orthodontic movement were not predictable, regardless of the direction of tooth movement.20 On the other hand, a dimished stability of the soft tissue is also not expected, because the periodontium was free of inflammation. Maintaining an interdental papilla in augmented sites continues to be a challenge. However, there is no data to suggest a rate of extrusion which effectively creates enough bone to create a papilla.21,22 In this novel case, moving the tooth horizontally maintained bone height such that when the crown was placed, there was
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less than 5 mm from the bone crest to the contact point. This 5 mm benchmark is considered appropriate to expect papilla formation. Unlike orthodontic extrusion, the mucogingival junction did not move occlusally with tooth movement. However the cleft of bone distal to the premolar was not addressed. In this case, due to the periodontally healthy conditions, thick biotype and good hygiene no further grafting was indicated. However if the patient was susceptible to attachment loss around the molar, orthodontic extrusion of the premolar to correct the defect between molar and premolar would have been indicated. Their observations agree with ours. We may go a step further and suggest that orthodontic tooth movement for implant site development and alveolar ridge development should be considered an alternative treatment option.
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Conclusion The present article shows a case where horizontal orthodontic tooth movement was used to augment a horizontally and vertically deficient alveolar ridge. Although ridge augmentation in the form of forced eruption was identified decades ago, horizontal tooth movement is also available as a modality as orthodontics enhances the restoration of missing teeth with dental implants. Orthodontic movement is a viable option for alveolar ridge development, but proper case selection, which includes attachment level, is crucial for the outcome success.
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