The purpose of this retrospective case series study was to present a new step-by-step surgical procedure known as the Custom Alveolar Ridge-Splitting CARS technique for maxillary anterio
The International Journal of Periodontics & Restorative Dentistry © 2021 BY QUINTESSENCE PUBLISHING CO, INC PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER 397 The Custom Alveolar Ridge-Splitting (CARS) Technique for Predictable Horizontal Ridge Augmentation in the Atrophic Anterior Maxilla: A Retrospective Case Series Study Stuart J Froum, DDS1 Raed O Kadi, BDS2 Buddhapoom Wangsrimongkol, DDS3 Parnward Hengjeerajaras, DDS2/Natacha Reis, DDS2 Paul Yung Cheng Yu, DDS4/Sang-Choon Cho, DDS2 Implant-supported restorations have proven to be a predictable option for replacing missing teeth In cases of inadequate bone quantity, the bone volume can be increased by bone augmentation procedures Several factors can affect bone regeneration, including the morphology of the defect at the implant site A defect surrounded by bony walls (an intraosseous defect) is known to yield a highly successful regeneration The purpose of this retrospective case series study was to present a new step-by-step surgical procedure known as the Custom Alveolar Ridge-Splitting (CARS) technique for maxillary anterior ridge augmentation This technique creates an intraosseous defect while splitting and augmenting an atrophic ridge Sixteen consecutive cases were treated with the CARS procedure All implants were restored and followed for 12 to 24 months after loading, and all cases were effectively treated with successful implant placement According to this retrospective study, the CARS procedure is simple, successful, and predictable and may be used as a surgical option for horizontal alveolar ridge augmentation in the anterior maxilla Int J Periodontics Restorative Dent 2021;41:397–403 doi: 10.11607/prd.5411 Ashman Department of Periodontology and Implant Dentistry, New York University College of Dentistry, New York, New York, USA; Private Practice, New York, New York, USA 2Advanced Program for International Dentists in Implant Dentistry, Ashman Department of Periodontology and Implant Dentistry, New York University College of Dentistry, New York, New York, USA 3Advanced Program for International Dentists in Implant Dentistry, Ashman Department of Periodontology and Implant Dentistry, New York University College of Dentistry; Master of Science in Oral Biology, New York University College of Dentistry, New York, New York, USA 4Ashman Department of Periodontology and Implant Dentistry, New York University College of Dentistry, New York, New York, USA 1 Correspondence to: Dr Stuart J Froum, 17 West 54th Street, Suite 1c/d, New York, NY 10019, USA Email: dr.froum@verzion net Submitted September 2, 2020; accepted September 13, 2020 ©2021 by Quintessence Publishing Co Inc Implant-supported restorations have been proven to be a predictable option for replacing missing teeth.1–3 To obtain successful, longterm outcomes, a sufficient volume of bone is required with at least mm of bone on the facial and oral aspects of the implant.4 In the anterior maxilla, the goal of therapy is to restore esthetics as well as function, which can present a challenge when the edentulous alveolar ridge is deficient in quantity and quality of bone.5 Alveolar bone loss, including contour changes, can occur by bone resorption and remodeling after tooth extraction, or it may occur pathologically prior to tooth extraction because of periodontal disease, periapical pathology, or trauma to teeth and bones.6 In cases of inadequate bone quantity, the bone volume can be increased by bone augmentation procedures in conjunction with or followed by implant placement.7 Ridge-splitting techniques have been described in one-, two-, and three-stage approaches.8–10 However, the technique described herein differs from each of these and is potentially more predictable To achieve an esthetic and functionally stable implant-supported fixed prosthesis, a combination of soft and hard tissue augmentation procedures is often necessary.4,11–13 Despite advancements in bone Volume 41, Number 3, 2021 © 2021 BY QUINTESSENCE PUBLISHING CO, INC PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER 398 Fig 1 Initial drilling is performed with the guide regeneration techniques, the outcomes in many cases are not highly predictable.14 Several factors can affect bone regeneration One of those is the morphology of the defect at the implant site, which has been reported to be a critical factor for the success of bone augmentation.14 A defect surrounded by bony walls is an intraosseous defect, and this type of defect is known to yield a highly successful regeneration due to good blood and osteoblast supply in addition to being well contained.15–17 In contrast, an extraosseous defect with fewer bony walls has been shown to be less predictable for bone augmentation procedures.15–17 The purpose of this retrospective case series study was to present a new step-by-step surgical procedure known as the Custom Alveolar Ridge-Splitting (CARS) technique for maxillary anterior ridge augmentation, document the results in 16 patients, and discuss the advantages and limitations of this technique Materials and Methods Clinical data was obtained from the Implant Database (ID) at New Fig 2 The guide cylinder in place Fig 3 A trephine bur is used, guided by the guide cylinder York University College of Dentistry (NYUCD) This data set was extracted as de-identified information from the routine treatment of patients at the Ashman Department of Periodontology and Implant Dentistry at NYUCD The ID was certified by the Office of Quality Assurance at NYUCD This study is in compliance with the Health Insurance Portability and Accountability Act requirements Sixteen consecutive cases were selected from patients who desired dental implants with a fixed prosthesis to replace their missing teeth in the anterior maxillary arch and had implants placed with the CARS procedure Eleven women and men (age range: 22 to 65 years; mean age: 45 years) were included All 16 cases were effectively treated with successful implant placement Follow-up times were recorded for each of the implants placed The CARS procedure follows a specific set of steps and can be modified according to the surgical scenario Following a CBCT of the surgical site, the point of entry of the trephine guide and trephine are determined on an axial section of the site After elevation of a full- thickness flap, the initial drilling is made with the help of a guide (Fig 1), and a guide cylinder is placed into this first osteotomy, which was prosthetically selected for future implant placement (Fig 2) A circular vertical cut is then created by an appropriately sized trephine bur (with the bur diameter similar to the diameter of the future implant) and guided by the guide cylinder (Fig 3) The guide cylinder is then removed, and the final cut is made with the same trephine bur to the planned length (2 mm more than the future implant length) During cutting, the surgeon evaluates the stability of the split segment If the segment is stable, the second stage can be performed in the same surgery If it is not stable, the flap is sutured, and reentry is performed to weeks later At the second stage, a greenstick fracture is created by the same trephine bur (or a small periosteal elevator or small bone carrier), and the segment is moved buccally and wedged in the surrounding buccal bone plate Again, the stability of the segment is evaluated If good stability is achieved, implant placement can then be attempted Otherwise, bone grafting is performed The International Journal of Periodontics & Restorative Dentistry © 2021 BY QUINTESSENCE PUBLISHING CO, INC PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER 399 to maintain the space, and the flap is sutured The patient then returns to weeks later, and the last stage is performed, including osteotomy and implant placement Tapered implants are the most indicated for this technique In the present study, implants were loaded to 21 months after implant placement In 11 cases, the CARS procedure was performed to weeks before implant placement In cases, the CARS procedure was performed simultaneously with implant placement and guided bone regeneration (GBR) In case, the CARS procedure was performed months prior to implant placement In case, the segment was fractured, and successful retreatment was performed months later The technique for all cases included in this study was first performed on a 3D model of the patient, printed from the CBCT scan file Using these models for surgical simulation familiarized the surgeon with the actual site and procedure that was to be performed on the patient It also allowed the clinicians to experience the risks and helped them evaluate whether the site was more amenable to a two- or three-stage approach and whether the site required augmentation by a GBR procedure or any other procedure to manage any associated conditions The following two case reports are examples to illustrate the technique with its various aspects and procedures Case A 22-year-old woman presented to the Ashman Department of Periodontology and Implant Dentistry at NYUCD missing her maxillary right canine She had a high smile line,18 malocclusion, and parafunctional habits The patient was first treated orthodontically (at the NYUCD’s Orthodontic Department) to manage the malocclusion and parafunctional habits before she was referred to restore her missing tooth (Figs 4a and 4b) For this patient, the CARS technique was performed weeks prior to implant placement All procedures were performed under local anesthesia (2% lidocaine, 1:100,000; Henry Schein) The initial surgery was performed with a crestal incision made at the edentulous site, extending from the maxillary right lateral incisor to the maxillary right first premolar, with intrasulcular incisions around the buccal aspects of the maxillary right lateral incisor and right first premolar This was followed by two vertical labial releasing incisions at the mesial aspect of the right lateral incisor and distal aspect of the right first premolar A full-thickness flap was then elevated Initial drilling was performed, and a guide cylinder was placed in the area that had been prosthetically selected for a future implant A circular vertical cut was created with a 4.3-mm–diameter trephine bur (Straumann) guided by the guide cylinder The guide cylinder was then removed, and the final cut was made with the same trephine bur with copious irrigation to the planned length (Figs 4c and 4d) During the cutting, the stability of the split segment was evaluated, and the decision was made to perform the second stage of the CARS procedure A greenstick fracture was created using a small bone carrier, and the segment was moved buccally and wedged in the surrounding buccal bone plate The stability of the segment was then evaluated and was found to be poor Therefore, a bone graft consisting of small particles of cancellous bovine bone (BioOss, Geistlich) was moistened with normal saline and packed in the newly created intraosseous defect (Fig 4e) The flap was then repositioned and adapted, and tension-free closure was achieved and stabilized by simple interrupted resorbable sutures (chromic gut 4/0 suture, Ethicon, Johnson & Johnson) The patient returned weeks later for the second surgery, and the last stage of the CARS procedure was performed under local anesthesia A crestal incision was made at the edentulous site on the maxillary right canine with intrasulcular incisions around the buccal aspect of the right lateral incisor and the right first premolar A full-thickness flap was then elevated without any vertical incisions An osteotomy was made, and the implant (4.1 × 10 mm, BLT SLActive Roxolid, Straumann) was placed following the specific implant protocol (Fig 5a) A periapical radiograph was then taken The flap was then repositioned and adapted, and tension-free closure was achieved and stabilized by interrupted resorbable 4/0 chromic gut sutures The implant was successfully restored months after Volume 41, Number 3, 2021 © 2021 BY QUINTESSENCE PUBLISHING CO, INC PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER 400 a b c Fig 4 Case (a) Clinical and (b) periapical radiographic views of the missing maxillary right canine (c) The final cut was created by the same trephine bur as before (Fig 3) (d) Clinical view after the final trephine cutting and (e) after bone grafting d e implant placement (Figs 5b and 5c) The patient returned for follow-up every months for 15 months (Fig 5d) During this time, years after implant placement, the implant and bone levels remained stable, with excellent function of the restoration (Figs 5e to 5g) Case A 29-year-old woman presented to the Ashman Department of Periodontology and Implant Dentistry at NYUCD missing a maxillary left central incisor (Figs 6a and 6b) The CARS technique was performed weeks prior to implant placement All procedures were performed using the same steps and materials used in Case 1, except the current patient received GBR simultaneously with implant placement The implant (4.1 × 10 mm, BLT SLActive Roxolid, Straumann) was placed at the central incisor site, and a GBR procedure was performed on the buccal aspect using bone graft material (Bio-Oss, particle size cc, Geistlich) and a resorbable membrane (Bio-Gide, Geistlich) with tacks Healing was uneventful (Fig 6c) The implant was successfully restored 12 months after placement and was followed for an additional 12 months (up to years postplacement), and stable bone and soft tissue levels were seen at 24 months postplacement (Figs 6d and 6e) Results In the 16 cases followed, all implants were successfully placed and restored (6 to 21 months after implant placement), and were followed up for 12 to 24 months after loading In case, the segment was fractured, and successful retreatment was completed months later: The implant was successfully placed and restored (6 months after implant placement), and was followed for an additional 24 months after loading To date, all 22 implants have functioned well with no failures or complications Appendix Table summarizes the placement, procedure, time of loading, and follow-up information of all 16 consecutive cases treated with the CARS technique (all Appendix Tables can be found in the online version of this article available at quintpub.com/journals) Patients and represent the first and second case reports, consecutively Discussion The present study introduces a new technique for horizontal ridge augmentation of atrophic ridges that can be used for single or two adjacent edentulous sites in the anterior The International Journal of Periodontics & Restorative Dentistry © 2021 BY QUINTESSENCE PUBLISHING CO, INC PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER 401 a b c d e f Fig 5 Case (a) Clinical view of the implant placed weeks after the first surgery (b) Occlusal and (c) periapical radiographic views of the final screw-retained crown at month postloading (d) Occlusal view at year postloading (e) Occlusal, (f) facial, and (g) periapical radiographic views at years postloading g a b c d e Fig 6 Case (a) Occlusal and (b) frontal views of the missing maxillary left central incisor (c) Occlusal view after the CARS technique, GBR, and implant placement (d) Clinical and (e) periapical radiographic views of the final screw-retained crown at 24 months postplacement Volume 41, Number 3, 2021 © 2021 BY QUINTESSENCE PUBLISHING CO, INC PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER 402 maxilla, in cases where the mesiodistal space is narrow for alveolar ridge-splitting, with a minimum narrow ridge width of mm It can also be used in the anterior mandible with the same minimum bone width In 2018, Hu et al published a modification of the alveolar ridge-splitting technique recommending the three-stage alveolar ridge-splitting technique.10 The CARS technique is a modification of the alveolar ridge-splitting technique The goal of the CARS technique is to create an intraosseous bony defect produced by designed cuts in the residual alveolar bone, which then becomes the future implant site after creating a greenstick fracture of the patient’s native bone based on those customized cuts The created intraosseous bony defect will contain a fresh blood clot rich in cells that can stimulate the osseous tissues healing and bone formation according to the regional acceleratory phenomenon and the buccal gap distance.19–21 The addition of a bone graft can prevent the collapse of the created space.22 These advantages and changes in the technique not require the periosteum supply to be maintained on the transported segment, as recommended in the original ridge-splitting technique.8 The CARS technique can simplify alveolar ridge augmentation surgical techniques, enhance the results of GBR, enable a more predictable and prosthetically oriented implant placement, be less invasive, and possibly minimize patient morbidity.11 However, it may require two to three staged procedures (but when conditions are optimum, the CARS technique can be done in one stage) In addition, the trephined bony segment could fracture, which occurred in one case in the present study: The fractured segment was repositioned and allowed to heal, and the implant and restoration were then successfully placed and continued to function well with 24 months of follow-up Currently, a wide range of surgical procedures are available for ridge augmentation However, it is difficult to demonstrate that any one of these can offer better outcomes than another.23 A comparison between GBR, block grafts, ridgesplitting, and the CARS techniques is presented in Appendix Table The ridge-splitting and the CARS techniques create intraosseous defects with horizontal and vertical incisions, respectively These intraosseous defects have demonstrated more predictable outcomes than extraosseous ones.15–17 Moreover, the CARS technique improves both soft and hard tissue morphology.12 However, all techniques are operator-sensitive and require surgical skill Training for the CARS technique presents an easy learning curve with the use of 3D models, which can be printed from the patient’s CBCT scan file Comparison with other augmentation procedures demonstrates that the CARS technique requires a smaller flap size, reducing surgical time and patient morbidity, thus potentially decreasing patient discomfort Conclusions Within the limitations of this case series, it can be concluded that the CARS technique may present another option for horizontal alveolar ridge augmentation in the anterior maxilla in cases of atrophic alveolar ridges Further research with a greater number of patients and case-controlled comparison studies are necessary to determine the success and advantages of the CARS technique compared to those conventionally used for horizontal ridge augmentation Acknowledgments An application for patent has been filed to protect the novel instruments and techniques described in this article The authors declare no conflicts of interest References Albrektsson T, Dahl E, Enbom L, et al Osseointegrated oral implants A Swedish multicenter study of 8139 consecutively inserted Nobelpharma implants J Periodontol 1988;59:287–296 Pylant T, Triplett RG, Key MC, Brunsvold MA A retrospective evaluation of endosseous titanium implants in the partially edentulous patient Int J Oral Maxillofac Implants 1992;7:195–202 Adell R, Eriksson B, Lekholm U, Brånemark PI, Jemt T Long-term followup study of osseointegrated implants in the treatment of totally edentulous jaws Int J Oral Maxillofac Implants 1990;5:347–359 Buser D, Brägger U, Lang NP, Nyman S Regeneration and enlargement of jaw bone using guided tissue regeneration Clin Oral Implants Res 1990;1:22–32 Salama H, Salama MA, Li TF, Garber DA Treatment planning 2000: An esthetically oriented revision of the original implant protocol J Esthet Dent 1997;9:55– 67 The International Journal of Periodontics & Restorative Dentistry © 2021 BY QUINTESSENCE PUBLISHING CO, INC PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER 403 Schropp L, Wenzel A, Kostopoulos L, Karring T Bone healing and soft tissue contour changes following single-tooth extraction: A clinical and radiographic 12-month prospective study Int J Periodontics Restorative Dent 2003;23:313– 323 Buser D, Martin W, Belser UC Optimizing esthetics for implant restorations in the anterior maxilla: Anatomic and surgical considerations Int J Oral Maxillofac Implants 2004;19(suppl):s43–s61 Scipioni A, Bruschi GB, Calesini G The edentulous ridge expansion technique: A five-year study Int J Peridontics Restorative Dent 1994;14:451–459 Elian N, Jalbout Z, Ehrlich B, et al A two-stage full-arch ridge expansion technique: Review of the literature and clinical guidelines Implant Dent 2008;17:16–23 10 Hu GH, Froum SJ, Alodadi A, et al Three-stage split-crest technique: Case series of horizontal ridge augmentation in the atrophic posterior mandible Int J Periodontics Restorative Dent 2018;38:565–573 11 Benic GI, Hämmerle CH Horizontal bone augmentation by means of guided bone regeneration Periodontol 2000 2014;66:13–40 12 Levine RA, Huynh-Ba G, Cochran DL Soft tissue augmentation procedures for mucogingival defects in esthetic sites Int J Oral Maxillofac Implants 2014;29(suppl):s155–s185 13 Simion M, Baldoni M, Zaffe D Jawbone enlargement using immediate implant placement associated with a split-crest technique and guided tissue regeneration Int J Periodontics Restorative Dent 1992;12:462–473 14 Muchhala S, Unozawa M, Wang WCW, Robins CG Treatment options for atrophic ridges based on anatomical locations of the missing teeth J Oral Biol 2018;5:6 15 Misch C, Misch CE Bone augmentation by deficit six and topography: The twoto five-bony wall defects Dentaltown 2010 16 Misch CM, Misch CE The repair of localized severe ridge defects for implant placement using mandibular bone grafts Implant Dent 1995;4:261–267 17 Cortellini P, Tonetti MS Clinical concepts for regenerative therapy in intrabony defects Periodontol 2000 2015;68:282–307 18 Tjan AH, Miller GD, The JG Some esthetic factors in a smile J Prosthet Dent 1984;51:24–28 19 Frost HM The regional acceleratory phenomenon: A review Henry Ford Hosp Med J 1983;31:3–9 20 Wilcko MT, Wilcko WM, Pulver JJ, Bissada NF, Bouquot JE Accelerated osteogenic orthodontics technique: A 1-stage surgically facilitated rapid orthodontic technique with alveolar augmentation J Oral Maxillofac Surg 2009;67:2149–2159 21 Greenstein G, Cavallaro J Managing the buccal gap and plate of bone: Immediate dental implant placement Dent Today 2013;32:70–77 22 Moreno Rodríguez JA, Ortiz Ruiz AJ, Zamora GP, Pecci-Lloret M, Caffesse RG Connective tissue grafts with nonincised papillae surgical approach for periodontal reconstruction in noncontained defects Int J Periodontics Restorative Dent 2019;39:781–787 23 Troeltzsch M, Troeltzsch M, Kauffmann P, et al Clinical efficacy of grafting materials in alveolar ridge augmentation: A systematic review J Craniomaxillofac Surg 2016;44:1618–1629 Volume 41, Number 3, 2021 © 2021 BY QUINTESSENCE PUBLISHING CO, INC PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER 403a Appendices Appendix Table 1 Case Details of All 16 Patients with Implants Placed Using the CARS Technique Implant sitea Age, y Gender Additional procedure Filling material Loading time, mo Follow-up time, mo 23 29 F GBR Bio-Oss 12 12 14 45 M None Bio-Oss 15 12 12, 22 65 M None Bio-Oss 15 12 21 22 M None Bio-Oss 13 12 13 60 M None Bio-Oss 12 15 11, 21 29 M GBR Bio-Oss 18 12 35 F None Bio-Oss 18 13 22 F None Bio-Oss 24 12 29 F None Bio-Oss 24 10 11, 21 34 F None Bio-Oss 18 11 11, 21 62 F None Bio-Oss 18 12 13 50 F None Bio-Oss 24 13 11, 21 51 M GBR Bio-Oss 18 14 24 65 F Fractured Bio-Oss 24 15 11, 21 50 F None None 18 16 12 30 F None Bio-Oss 18 Patient no CARS = Customized Alveolar Ridge-Splitting; F = female; GBR = guided bone regeneration; M = male All Bio-Oss (Gesitlich) filling material used small particle sizes (1 cc) a FDI numbering system Appendix Table 2 Comparison Between GBR and Block Grafts, Ridge Splitting, and CARS Techniques GBR and block graft Ridge splitting CARS Osseous defect Intra- or extraosseous Intraosseous Intraosseous Cutting direction Decortication Horizontal cutting Vertical cutting Wound size Large Large Small Technique Operator-sensitive Operator-sensitive Operator-sensitive (easy learning curve with 3D models) High High TBD Incidence of use CARS = Customized Alveolar Ridge-Splitting; GBR = guided bone regeneration; TBD = to be determined The International Journal of Periodontics & Restorative Dentistry © 2021 BY QUINTESSENCE PUBLISHING CO, INC PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER Copyright of International Journal of Periodontics & Restorative Dentistry is the property of Quintessence Publishing Company Inc and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's 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