INTRODUCTION
Because significant bone loss tends to occur following the loss of a tooth, providing implant treatment in an area that has been edentulous for an extended period of time can present unique challenges, especially in cases where single-stage surgery is desired.1 The presence of a thin ridge or a facial concavity can limit the space available for implant placement, requiring bone augmentation to ensure a predictable, aesthetic outcome.2 While bone grafting with delayed implantation is often treatment planned in these situations, ridge splitting and expansion is a technique that allows for immediate implant placement.
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| Figure 1. Preoperative condition of the patient, who presented with deficient ridge width in the area of her missing maxillary right premolars and a minor facial undercut. |
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| Figure 2. Sagittal view of a CBCT scan illustrates the thin residual ridge that was approximately 2.4 mm wide at the time of initial consultation. | Figure 3. A saw-shaped insert was used to create a horizontal cut in the bone and bisect the residual ridge. |
In combination with proper bone regeneration techniques, ridge splitting with immediate implantation has been shown to predictably expand the crestal ridge, leading to excellent implant survival rates.3-5 This affords patients who present with a compromised ridge the benefits of immediate implant placement, including preservation of the hard and soft tissue, less surgical trauma, and excellent final aesthetics.6,7 By reducing the number of surgical appointments and shortening the duration of treatment, this approach provides patients with an appealing alternative to a more surgically intensive lateral bone augmentation procedure with delayed implant placement.
To perform the ridge-splitting procedure, the bone of the residual ridge is bisected mesial-distally, and 2 vertical cuts are created on the facial aspect of the buccal cortical plate. This allows for expansion of the ridge toward the facial using a series of bone chisels and ridge expanders. Determining whether this form of treatment is indicated requires a careful evaluation of the patient’s bone anatomy. Ridge splitting and expansion is indicated for patients with a native ridge thick enough to accommodate a 3.5-mm diameter (or larger) implant after the procedure has been performed. If the patient’s ridge is too thin, or there is a severe facial undercut, the buccal cortical plate is at risk of fracturing or dislodging during the ridge-splitting procedure.8 The facial aspect of the ridge must be well-defined, and there must be ample trabecular bone present between the 2 cortical layers. The patient’s bone quality is a factor, as dense D1 bone contraindicates ridge splitting. A thick gingival biotype is also necessary because there must be sufficient soft tissue to contain the expanded ridge and achieve tension-free closure.
The following case report illustrates how to utilize ridge splitting and expansion to facilitate single-stage surgery for patients who present with a deficient residual ridge. In addition to demonstrating how to determine whether this procedure is indicated for the individual patient, this presentation will outline the basic treatment protocol, including splitting, expansion, and grafting of the ridge; proper implant selection and placement; and how to achieve an ideal restorative outcome.
CASE REPORT
Diagnosis and Treatment Planning
A 40-year-old female patient presented for treatment with missing teeth in the area of teeth Nos. 12 and 13 (Figure 1). The teeth were extracted several years prior after the failure of endodontic treatment. The patient, who was in generally good dental health, had grown tired of wearing a partial appliance and requested a better long-term solution. Because socket grafting was not performed and the teeth had been missing for a number of years, the ridge in the area of the edentulous span had resorbed significantly. There was also a minor facial undercut present. Intraoral examination and CBCT analysis revealed that, although there was plenty of space between the crest of the ridge and the floor of the sinus, the width of the ridge was not sufficient for immediate implantation without the threads of the implant fracturing or protruding through the buccal plate (Figure 2). However, evaluation of the edentulous span and the patient’s bone anatomy indicated that, following a ridge splitting and expansion procedure, 2 implants could be safely and predictably placed.
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| Figure 4. Two vertical cuts were extended through the facial cortical plate at lengths corresponding with the 3.5- x 10-mm and 4.3- x 8-mm implants selected for the procedure. | Figure 5. A series of Medco Instruments bone chisels was used to gradually expand the residual ridge by lightly tapping each instrument with a lightweight medical mallet. |
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| Figure 6. Medco Ridge expanders were threaded into the split ridge with a ratchet wrench, creating the osteotomies for the implants. | Figure 7. The Hahn Tapered Implants (Glidewell Laboratories) were positioned in the sequentially widened ridge and afforded precise directional control as they were threaded into place. |
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| Figure 8. The Newport Biologics Mineralized Cortico/Cancellous Allograft Blend was hydrated with platelet-rich fibrin. | Figure 9. After filling the split ridge and covering the site with the allograft material and a collagen membrane, the soft tissue was closed with a PTFE suture. |
The patient exhibited D3-type bone, with plenty of trabecular bone between the cortical plates, and thick, keratinized soft tissue. Measurements recorded with an iCAT FLX CBCT scanner helped determine that, following ridge expansion, a 3.5- x 10-mm implant could be placed in the area of tooth No. 12 and a 4.3- x 8-mm implant in the area of tooth No. 13.
After the treatment options were presented to the patient, she agreed to a treatment plan in which ridge splitting, bone grafting, and implant placement would be performed during a single surgical appointment. This approach was more appealing to the patient than lateral ridge augmentation with delayed implant placement because she wished to minimize the length of treatment and the number of surgical procedures.
Surgical Protocol
The surgical protocol for ridge splitting includes flap reflection, bone cutting, expansion of the ridge, implant placement, bone grafting, and site closure. The site must always be covered following the procedure, with 4 to 6 months allowed for healing, bone regeneration, and osseointegration. In addition to the typical instrumentation required for dental implant surgery, the armamentarium for this procedure includes a bone cutting instrument, ridge split chisels, a lightweight medical mallet, a bone expander kit, cortico/cancellous grafting material, and a resorbable collagen membrane.
To begin the surgical procedure, a full-thickness flap was reflected with mid-crestal and vertical releasing incisions. This allowed for complete visualization of the crestal and buccal aspects of the resorbed ridge. Then a series of cuts was made to facilitate expansion of the ridge toward the facial. An ENAC OE-F15 piezoelectric ultrasonic system (Osada) and a saw-shaped insert were used to cut into the crestal bone, bisecting the residual ridge at a depth corresponding with the implant lengths selected for the procedure (Figure 3). The mesial-distal cut across the crest of bone was situated 1.5 mm from the adjacent teeth and extended a total of 11.0 mm, allowing for 3.0 mm of space between the 3.5- and 4.3-mm diameter implants. Beginning at each end of the cut bisecting the crest of the maxilla, 2 vertical cuts were extended apically through the dense cortical bone, down the facial aspect of the ridge (Figure 4). Next, a series of progressively wider Medco ridge split chisels was used to expand the bone toward the facial aspect of the ridge by lightly tapping the handle of each instrument with a lightweight medical mallet (Figure 5). Firm finger pressure was applied to the palatal and facial aspects of the maxilla as the ridge was expanded. A Medco bone expander kit was then used to create the implant osteotomies with a minimal amount of surgical trauma. Using a ratchet wrench, the bone expanders were tightened into the bisected ridge in alignment with the planned implant locations (Figure 6). The ridge expanders were taken to depth, thread forming the bone and gradually creating enough space to accommodate the 3.5- x 10-mm and 4.3- x 8-mm implants.
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| Figure 10. At 4 months post surgery, this occlusal view shows the improved ridge width and successful bone and soft-tissue regeneration. | Figure 11. The implant restorations, which were splinted for optimal support, were designed with precision using dental CAD software. |
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| Figure 12. The healing abutments were removed, revealing well-contoured tissue that would support an aesthetic emergence profile. | Figure 13. The Inclusive Titanium Custom Abutments (Glidewell Laboratories) were delivered and established precise margins slightly beneath the gingival surface. |
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| Figure 14. Complete seating of the custom abutments was verified radiographically. Note the thorough integration of the Hahn Tapered Implants in the expanded ridge. | Figure 15. The final delivery of the monolithic zirconia crowns (BruxZir Full-Strength Solid Zirconia [Glidewell Laboratories]) established a precise fit over the custom abutments. |
Hahn Tapered Implants (Glidewell Laboratories) were selected for their aggressive thread design and ability to fit within tight anatomical spaces. Each implant was initially threaded into place using an AEU 7000 Series motor (Aseptico) and handpiece at 15 rpm, and a torque wrench was used to achieve final seating (Figure 7). The tapered shape of the implants helped ease positioning into the confined space of the split ridge, and the deep, sharp threads helped stabilize and maintain the desired positioning during insertion.
Cover screws were then connected to the implants, and Newport Biologics Mineralized Cortico/Cancellous Allograft Blend was hydrated and inserted into the gap in the expanded ridge, filling all spaces where the implants were not in contact with bone (Figure 8). The grafting material’s combination of cortical and cancellous bone particulate excels both in maintaining space and regenerating bone, making it ideal for ridge splitting and expansion procedures. Bone particulate was also added in front of the buccal cortical plate and over the top of the implants and the exposed ridge. Newport Biologics Resorbable Collagen Membrane 4-6 was positioned over the ridge and covered with platelet-rich fibrin. Primary closure of the site was achieved with a PTFE suture (Figure 9).
Restorative Protocol
The patient returned after 4 months for assessment of the ridge and implant stability (Figure 10). The site was uncovered by making a single crestal incision, revealing a thick, healthy ridge. The implants exhibited high stability and thorough integration within the bone of the expanded ridge. Hahn Tapered Implant System Healing Abutments (Glidewell Laboratories) were attached to the implants to develop an aesthetic emergence profile for the final restoration, and the site was sutured.9
One month later, open-tray transfer posts were connected to the implants, and VPS impressions were taken. Based on the final impressions, Glidewell Dental designed inclusive titanium custom abutments and final crowns utilizing advanced dental CAD software (Figure 11). The custom abutments were designed to ensure proper marginal placement 0.5 mm beneath the gingival surface. Monolithic zirconia crowns (BruxZir Full-Strength Solid Zirconia [Glidewell Laboratories]) were chosen to ensure long-term durability, which is ideal for implant restorations in the posterior.10
At the final delivery appointment, removal of the healing abutments revealed healthy sulcus forms surrounding the Hahn Tapered Implants (Figure 12). The custom abutments were seated and conformed precisely to the soft-tissue anatomy at the implant sites (Figure 13). After tightening the prosthetic screws, complete seating of the custom abutments was confirmed radiographically (Figure 14). The final monolithic zirconia crowns were delivered, producing a predictable, aesthetic outcome for the patient despite the ridge deficiency present at the time of initial consultation (Figure 15).
CLOSING COMMENTS
Ridge splitting and expansion is an underutilized, advantageous procedure that can facilitate immediate implantation in many cases that would otherwise demand a “graft and wait” protocol. The diagnostic, treatment planning, and surgical aspects of this streamlined approach to implant treatment are accessible to any practitioner experienced with bone grafting and immediate implant placement. By adopting some simple tools and techniques, clinicians can reduce appointments, surgical trauma, and treatment time for patients who present with a deficient residual ridge.
Acknowledgment
The author would like to thank Glidewell Laboratories in Newport Beach, Calif, for the implants, crowns, and custom abutments fabricated for this case.
References
- Kordatzis K, Wright PS, Meijer HJ. Posterior mandibular residual ridge resorption in patients with conventional dentures and implant overdentures. Int J Oral Maxillofac Implants. 2003;18:447-452.
- Cardaropoli D, Tamagnone L, Roffredo A, et al. Evaluation of dental implants placed in preserved and non-preserved post-extraction ridges: a 12-month post-loading study. Int J Periodontics Restorative Dent. 2015;35:677-685.
- Bruschi GB, Capparé P, Bravi F, et al. Radiographic evaluation of crestal bone level in split-crest and immediate implant placement: minimum 5-year follow-up. Int J Oral Maxillofac Implants. 2017;32:114-120.
- 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.
- Jamil FA, Al-Adili SS. Lateral ridge splitting (expansion) with immediate placement of endosseous dental implant using piezoelectric device: a new treatment protocol. J Craniofac Surg. 2017;28:434-439.
- Ebenezer V, Balakrishnan K, Asir RV, et al. Immediate placement of endosseous implants into the extraction sockets. J Pharm Bioallied Sci. 2015;7(suppl 1):S234-S237.
- Covani U, Cornelini R, Calvo JL, et al. Bone remodeling around implants placed in fresh extraction sockets. Int J Periodontics Restorative Dent. 2010;30:601-607.
- Sohn DS, Lee HJ, Heo JU, et al. Immediate and delayed lateral ridge expansion technique in the atrophic posterior mandibular ridge. J Oral Maxillofac Surg. 2010;68:2283-2290.
- Qi Y, Zhang J, Hasi BG, et al. Clinical study of healing abutment on sealing socket and preservation of the gingival natural profile in single-tooth immediate implantation [in Chinese]. Zhonghua Kou Qiang Yi Xue Za Zhi. 2008;43:299-301.
- Christensen GJ. Translucent zirconias: tooth reduction & chairside adjustment issues. Clinicians Report. 2016;9:1-3.
Dr. Patel is a graduate of the University of North Carolina at Chapel Hill School of Dentistry and the Medical College of Georgia/AAID MaxiCourse. He is a clinical instructor at the Reconstructive Dentistry Institute. Dr. Patel has placed more than 5,000 implants, published numerous articles in leading dental journals, and worked as a lecturer and clinical consultant on dental implants and prosthetics for various companies. He belongs to numerous dental organizations, including the ADA, North Carolina Dental Society, and the American Academy of Implant Dentistry (AAID). For information on his upcoming dental implant courses, visit glidewellcecenter.com. He can be reached by visiting implantsbyparesh.com or via email at pareshpateldds2@gmail.com.
Disclosure: Dr. Patel reports no disclosures.
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