In the moderately to severely atrophic maxilla,

Transcription

1 Staged Sinus Floor Elevation Using the Crestal Core Elevation (CCE) Procedure: A Review of the Technique Michael, DDS Abstract In the moderately to severely atrophic maxilla, trephined cores measuring 3 to 6 mm in height and 5 to 6 mm in diameter may be apically displaced to facilitate sinus augmentation and staged implant placement. The crestal core elevation (CCE) procedure incorporates specially designed core osteotomes to minimize membrane perforation and the malleting force associated with core intrusion. This report reviews the technique, instrumentation and indications for CCE and presents two clinical cases clearly demonstrating the efficacy of this less invasive alternative to the more commonly used lateral window osteotomy. KEY WORDS: Maxillary sinus, bone graft, dental implant, platelet rich fibrin, PRF 1. Private practice limited to periodontics and dental implants, New York, New York, USA

2 Introduction A residual subantral deficiency of bone volume can be predictably augmented by a variety of sinus floor elevation (SFE) techniques incorporating a wide range of graft materials in a delayed or simultaneous approach to implant placement. 1-9 The lateral window osteotomy (LWO) is certainly the most frequently reported technique, producing reliable long-term results in reconstruction of the atrophic posterior maxilla. 6,10-11 While the quantity of preexisting bone required for successful simultaneous implant placement has not yet been determined, adequate bone should be available to provide primary implant stability. 12 A staged lateral window osteotomy (LWO) is most often advised when less than 5 mm of residual subantral bone height (RSBH) is present 8 although successful results have been reported in 2 to 3 mm of subantral bone. 13 Sites with less than 5 mm of RSBH have also demonstrated an increased failure rate when treated with osteotome-mediated sinus floor elevation (OMSFE) Summers 3 bone-added osteotome sinus floor elevation (BAOSFE) procedure was originally recommended at sites with at least 5 to 6mm of RSBH, limiting this treatment to patients with only a moderately atrophic posterior maxilla. Summers 4 introduced the future site development (FSD) procedure as an alternative to the lateral window approach in the more severely resorbed posterior maxilla where there was inadequate crestal bone present for primary stabilization of implants. In the FSD procedure, the residual subantral bone is imploded in the form of a plug with the aid of wide diameter (5 to 6mm) osteotomes and trephines as needed. The attached plug or core of native bone and added graft materials are used to elevate the sinus floor (Figures 1-5). The reported advantages of a staged crestal approach using the FSD procedure included decreased morbidity, a reduced healing time and avoiding direct contact of the sinus membrane with dental instruments. 4 Since the introduction of the future site development (FSD) procedure, 4 there have been no published reports on the success, predictability or complications experienced with the technique. A modification of the FSD procedure, crestal core elevation (CCE) was introduced by, 12,17 incorporating specially designed core osteotomes and barrier membrane placement over the core prepation(s). These modifications, when applied to the FSD procedure, simplified the technique, minimized membrane perforation and improved bone quality and healing. Using only a trephine for core preparation as described in the FSD technique 4 and later in the modified trephine osteotome technique, 18 it is difficult to uniformly prepare the core close enough to the sinus floor so that the core can be gently intruded Figure 1: Dental scan taken in 1998 prior to performing future-site development (FSD) procedure revealed 3 mm of subantral bone at site #14. with an osteotome. Core elevation requires significant malleting force unless the core has been prepared to within 1 mm of the sinus floor along its entire perimeter (Figure 6). Trephine preparation is most certainly complicated by variations in the topography of the residual alveolar ridge and sinus floor (Figure 7) that can lead to underpreparation at points along the core perimeter, preventing controlled intrusion of the core. Conversely, in an effort to more closely approach the sinus floor, additional trephine preparation can result in severe laceration of the sinus membrane and possible core removal or displacement into Figure 2: 6 mm diameter cores prepared at site #s 14 and 15. Figure 4: Core osteotomies grafted with bovine bone mineral (BBM) and apically displaced to further elevate sinus floor. the sinus cavity. To further simplify core preparation and reduce the risk of membrane laceration, 12,17 designed core osteotomes (H & H Co, Ontario, CA) which are used to prepare the apical 1 to 2mm of the core as it approximates the sinus floor. These instruments are one-third round and 0.5 mm thick and fit precisely around the 5.0 or 6.0mm core preparation (Figures 8-10). Figure 3: After significant malleting force, cores were elevated and membrane inspected for perforation. Figure 5: Periapical radiograph from 2002 after restorations in function for 3 years. While gently malleting these instruments, the clinician retains the tactile sensation lost when using a trephine to complete the most delicate aspect of the core preparation. 12 The core osteotomes directly infracture the sinus floor along the core s periphery significantly lessening the apical force required for core displacement. 12 reported on 43 partially edentulous patients with a mean

3 Figure 6: Trephine must ideally prepare cores to within 1 mm of the sinus floor to facilitate core intrusion. Figure 7: Trephine preparation is complicated by variations in the topography of the residual ridge and sinus floor, making it hard to uniformly prepare the core to ideal working depth. Figure 11: 5 mm cores have been prepped at site #s 14 and 15 to a depth of 3 to 4 mm Figure 10: After a 5 mm core has been prepared to within 1 to 2 mm of the sinus floor, the #5 core osteotome is rotated around the 5 mm diameter core and gently malleted to directly infracture the sinus floor along the core perimeter. There is 4 mm of RSBH; therefore, the osteotome will be inserted to the second line (4 mm). Figure 8: The core osteotome (H & H Co, Ontario, CA) is one-third round with a 0.5 mm thick curved tip designed to fit around the 5 mm or 6 mm core preparation. Figure 9: The #6 core osteotome is pictured with a 6 mm diameter trephine. Both have 2 mm markings. Figure 12: Apical displacement of the cores to the depth of the sinus floor (4 mm). Osteotome-mediated sinus floor elevation (OMSFE) performed at site #13. age of 56 (range 36 to 72 years). Staged sinus augmentation using CCE was performed at 73 sites where there was a minimum residual ridge width (RRW) of 6mm and a RSBH 5mm or less (mean 3.2 mm). Multiple sites were treated in 22 patients. The core osteotomies were grafted with a composite of 20% to 60% autogenous bone mixed with bovine bone and covered with either an e-ptfe membrane or a bioabsorbable collagen membrane. In all cases where implants were placed, the distance between the healed alveolar crest and sinus floor was at least 8 to 9 mm. Radiographic analysis of the areas treated with CCE showed a 6 mm to 12 mm increase in available bone height for implant placement. The resistance of the regenerated tissues was typical of type III to IV bone. In areas where 8 to 9 mm of subantral bone height was present, additional OMSFE was performed to allow for placement of an implant 10 to 11.5 mm in length. At the time of clinical review, adequate healing (5 to 7 months) had allowed for placement of 57 threaded implants in 33 of 43 patients. Implant length ranged from 10 mm to 13 mm (mean: 11.3mm) and the diameter 3.75 to 5.5mm (mean:

4 Figure 13: Positioning of 5 mm core preparations at site #s 13, 14 & 15 marked with a round bur using a surgical guide. Figure 14: 6 mm core preparation at site #3 into the facial and palatal plates of bone not only increases the risk for crestal bone loss, but also makes core elevation more difficult. Figure 15: Core preparation is initiated with a trephine with an internal diameter of 5.0 or 6.0mm and markings at 2.0, 4.0, 6.0, and 8.0mm (H and H Co. Ontario, CA) 4.6mm). Thirty-seven of the 57 implants placed had been loaded for 3 to 35 months (mean 15.5 months) with no failures during the study period. 12 This report will review and update the technique, demonstrating the efficacy of the procedure in two clinical cases. Figure 16: At site #3 with a RSBH of 6 mm, a #5 core osteotome malleted to a depth of 6 mm on the facial aspect of a 5 mm core at site #3. Materials and Methods Staged sinus grafting using CCE is traditionally performed at maxillary premolar and molar implant sites with a RSBH of 3 to 6 mm and a residual ridge width (RRW) 7mm to retain at least 0.5 to 1.0 mm of crestal bone facial and palatal to a 5 mm or 6mm core preps which have external diameters of 6 mm and 7 mm respectively (Figures 11-12). If multiple sites are treated, then sites with as little as 2 mm RSBH may be successfully augmented as well, but the author prefers performing a LWO with less than 3 mm of RSBH. All patients undergoing CCE receive a 1 to 2 hour preoperative dose of an antibiotic and 8 mg dexamethasone sulfate which is tapered to 4 mg the following 2 days and 2 mg on the third postoperative day. The majority of patients are sedated with midazolam and their blood pressure, pulse and po 2 are closely monitored throughout the procedure. After obtaining adequate local anesthesia, a crestal incision is made throughout the entire edentulous area. An anterior releasing incision is made on the mesial aspect of the adjacent tooth. The posterior releasing incision is placed distal to the tuberosity in those patients where autogenous bone will be obtained. A surgical guide and 2mm round drill may be used to locate the center of the crestal core at the site of future implant placement (Figure 13). Core diameter is based on the RRW and ideally, there should be at least 1.0 mm of palatal and facial bone outside the core preparation. Core preparation into the facial and palatal plates of bone will not only jeopardize their survival but also make core elevation more difficult (Figure Figure 17: The core osteotome is then rotated a onethird turn and advanced to 6 mm depth on the mesial and mesiopalatal aspect. One more rotation completes the apical preparation. 14). Core preparation is initiated with a trephine with an internal diameter of 5.0 or 6.0mm and markings at 2.0, 4.0, 6.0, and 8.0mm (H and H Co. Ontario, CA) (Figure 15). The initial bite of the trephine is created by operating the trephine in reverse at 500 RPM with external irrigation. The core is then prepared with the trephine (forward at 850RPM) to the desired working depth of 1 to 2 mm from the sinus floor in the area of most limited bone height. The one-third round #5 or #6 core osteotome (H & H Co, Ontario, CA) has a 0.5mm thick tip and fits around the 5.0 or 6.0mm core (Figure 16-17). While gently malleting and rotating the core osteotome, the clinician retains the tactile sensation lost when using a trephine in close approximation to the sinus floor. The sinus floor can now be directly infractured along the perimeter of the core to facilitate

5 Figure 18: Apical preparation with the core osteotome simplifies core intrusion to a depth of 6 mm, effectively doubling the height of the subantral bone. Figure 19: The core osteotomy has been grafted with mineralized freeze-dried bone allograft (MFDBA) in advance of collagen membrane coverage. Figure 21: A 6 mm core displaced 4 to 5 mm at site #3. Figure 22: A PRF plug has been inserted to fill the osteotomy prior to membrane placement. Figure 20: An autologous plug of platelet-rich fibrin (PRF) may be used to fill the osteotomy or inserted as membrane protection prior to additional sinus elevation with particulate materia apical displacement. Using a 5mm or 6mm diameter concave-tipped osteotome with 2mm markings up to 8mm (H & H Co, Ontario, CA), the core is displaced to the original level of the sinus floor (Figure 18). The integrity of the sinus membrane must then be confirmed by visual inspection. At this point you have technically doubled the amount of subantral bone by apically displacing the full length of the bone cylinder. If this RSBH is sufficient (at least 8.0 to 9.0 mm) then the osteotomy may be grafted with a particulate material (Figure 19) or platelet-rich fibrin (PRF) (Figures 20-22). If the estimated bone augmentation has created less than 8.0mm of subantral bone then PRF is placed in the osteotomy in advance of 2 to 3 loads bovine bone mineral or mineralized freeze-dried bone allograft (FDBA) and similar to the BAOSFE procedure, the graft materials are displaced to the original level of the sinus floor to achieve an additional 2.0 to 3.0mm of SFE. The grafted osteotomy is then covered with a bioabsorbable porcine type I collagen membrane (OSSIX-PLUS, OraPharma, Warminster, PA), (Figure 23). This collagen membrane has recently demonstrated fully submerged barrier function for up to 29 weeks as well as ossification of its cross-linked collagen. 19 To stabilize the membrane and facilitate primary closure, a combination of horizontal mattress and interrupted sutures are placed using PTFE monofilament suture (Osteogenics Biomedical Inc, Lubbock, TX). Tensionfree closure of the flap is obtained with the aid of vertical releasing incisions at the mesial and distal Figure 23: The grafted osteotomy has been covered with a bioabsorbable porcine type I collagen membrane (OSSIX- PLUS, OraPharma, Warminster, PA). Figure 24: An immediate postoperative radiograph taken to confirm successful core intrusion at site #s 3 & 4. Overlying membrane was stabilized by 3 tacks to aid in ridge augmentation site #5. extremes and/or periosteal releasing incisions, if necessary. Sutures are removed 10 to 14 days later. An immediate postoperative radiograph is taken to confirm graft containment and to determine the extent of sinus floor elevation (Figure 24). Postoperative care consists of an antibiotic (amoxicillin 500mg three times daily for 7 days), a decongestant (pseudoephedrine 120mg two times daily for 3 days), and rinsing with 0.12% chlorhexidine mouthwash twice daily until the patient returns 10 day later for suture removal. Additionally, the patient is instructed not to blow their nose and to sneeze with an open mouth. Patients are also advised to refrain from using any removable prostheses until the sutures are removed. After a healing

6 Figure 25: Site #3 with a RSBH of 3 to 5 mm and sinus septa. Figure 26: 6 mm core preparation to a depth of 3 mm. Note buccal defect. Figure 27: Apical core displacement to a depth of 5 mm. Figure 28: BBM was packed into osteotomy and apically displaced to achieve additional sinus floor elevation. period of 4 to 5 months, a periapical radiograph is taken to estimate the available bone height prior to implant placement. A crestal incision is used to expose the healed ridge. The implant sites are marked with a 2mm round drill using a surgical guide. The augmented site generally demonstrates type III or IV bone quality and presents minimal resistance to drilling. Most often, drills are utilized to prepare the osteotomy to its final diameter (0.7 mm to 1mm less than the implant diameter) at a depth of 5 to 6mm then osteotomes are used to further consolidate the bone apically. They may also provide for additional sinus elevation, if needed, to allow for the placement of a 10mm to 11mm long implant. If excellent primary stability is achieved (30 Ncm of insertion torque or a favorable ISQ reading), then healing caps are immediately placed otherwise the implants will heal in a submerged fashion. Healing progresses for another three to five months, at which time, those implants placed using a single-stage protocol are restored or the submerged implants are uncovered and healing caps placed. Case Presentations Case 1 A 61 year-old male recently lost tooth #3 due to mesiobuccal root fracture and extensive furcal bone loss. He sought a second opinion after a lateral window osteotomy (LWO) and staged implant placement had been recommended. The periapical radiograph reveals 3 to 5 mm of RSBH as well as a sinus septum which certainly increases the risk for membrane perforation using a lateral approach (Figure 25). In addition, a thick lateral sinus wall and membrane dissection around the roots of #2 also increased the degree of difficulty in performing a LWO. As a less invasive and less costly alternative, CCE was recommended in combination with staged implant placement. Figure 29: Postoperative radiograph demonstrates 8 mm of SFE. Flap elevation revealed a residual buccal defect and a 10 to 11 mm wide ridge which permitted preparation of a 6 mm diameter core (Figure 26). The core was prepared with a trephine to a depth of 3 mm, and then the #6 core osteotome was used to advance the preparation an addi- Figure 30: Five months later, the ridge had completely healed and the implant osteotomy was prepared with a combination of drills and osteotomes.

7 Figure 34: Dental scan, panoramic view of URQ reveals missing teeth #s 4 & 5, a sinus septa and membrane thickening. Figure 35: Dental scan, cross section site #4 shows septa, which certainly makes a lateral approach difficult Figure 31: Single stage implant placement of a 6 x 11.5 mm tapered implant. Figure 32: Implant-supported restoration site #3 after 5 years in function tional 1 to 2 mm and infracture the sinus floor around the core perimeter. This facilitated simple core intrusion to a depth of 4 to 5 mm using a 6 mm diameter concave-tipped osteotome (Figure 27). The osteotomy was packed with bovine bone mineral (BBM) and apically displaced 3 to 4 mm to achieve some additional sinus floor elevation (SFE). At present, PRF is always placed in advance of any graft material, but this autologous product was not available at the time this patient was treated. The osteotomy was then back-filled with BBM (Figure 28), covered with a bioresorbable collagen membrane and the tis- Figure 33: Periapical radiograph of implant after 5 years of loading. sues primarily closed. An immediate postoperative radiograph revealed graft containment and 7 to 8 mm of SFE (Figure 29). Five months later the ridge had completely healed and the implant osteotomy was prepared with a combination of drills and osteotomes (Figure 30) to allow for the placement of a 6 x 11.5 mm tapered implant (Figure 31). The implant supported restoration has now been in function for 7 years (Figures 32-33). Case 2 A 57 year-old female had recently lost tooth #5 contributing to failure of a fixed prosthesis incorporating tooth #s 3 and 6, replacing missing #4. Replacement of the fixed prosthesis was not considered as #3 demonstrated a moderate degree of bone loss and furcation involvement. The panoramic view from the dental scan revealed a sinus septa at site #4 and a residual defect and thickened sinus membrane at site #5 (Figure 34). A radiographic cross-section at site #4 shows the septa clearly with 3 to 4 mm of RSBH (Figure 35). A lateral approach at this site would most likely result in significant membrane perforation. Flap elevation allowed for the preparation and 4 to 5 mm apical displacement of a 5 mm core at site #4 and simple OMSFE at site #5 (Figure 36). The core osteotomy at #4 and the buccal defect at site #5 were grafted with MFDB (Figure 37) and covered with PRF and a bioresorbable Figure 36: Core elevation site #4 and OMSFE site #5. Figure 38: Immediate postoperative radiograph shows core intrusion #4 and OMSFE #5 Figure 37: Grafting site #s 4 & 5 with mineralized freezedried bone allograft (MFDBA). Figure 39: 6 months later, 4 mm diameter implants placed into the healed ridge.

8 Figure 40: Radiograph taken 4.5 months later at implant uncovering reveals substantial SFE. collagen membrane. The immediate postoperative radiograph clearly demonstrated apical core dipsplacement at #4 and localized OMSFE at #5 (Figure 38). Five months later, 4 mm diameter implants were placed into the healed ridge with excellent primary stability (Figure 39). Four months later SFE and successful integration was demonstrated radiographically around the 9mm and 13 mm long implants (Figure 40). Discussion The author has nearly completed analyzing the data on sites treated using the CCE procedure with implants in function from 1 to 10 years. As of September 2009, 125 patients have been treated with CCE performed at a total of 152 sites. Implant Figure 41: A LWO is more difficult to perform at single molar sites due to restricted access, a thicker lateral sinus wall and the presence of adjacent tooth roots. survival with up to 10 years of loading is approximately 94%, certainly equaling that reported for sinus floor elevation using a lateral approach. 10,11 A full clinical report on implants placed using CCE is in press and should be published shortly. This report updates the technique the author introduced in and reviewed in and The CCE procedure incorporates modifications to Summers (1995) original FSD procedure designed to reduce potential complications and provide more predictable, rapid healing while using the more conservative crestal approach to staged sinus augmentation surgery. SFE using the CCE procedure requires significantly less flap elevation and graft materials resulting in reduced postoperative pain, bruising and swelling. The LWO is easiest to perform in the totally edentulous posterior maxilla, but it is technically more difficult at single molar sites where a membrane perforation rate of 40% to 58% has been reported. 21,22 The introduction of piezosurgical instrumentation has reduced the incidence of membrane perforation during window preparation, 23 but a higher incidence of intraoperative complications would still be expected at single tooth sites due to restricted access, limited size of the antrostomy, increased thickness of the lateral sinus wall (Figure 41) and the presence of adjacent teeth. CCE has proven to be a most effective alternative to the LWO at these sites where quite often patients can provide only limited access to successfully utilize a lateral approach. Disclosure The author reports no conflicts of interest with anything mentioned in this article. References 1. Boyne PJ, James RA. Grafting of the maxillary sinus floor with autogenous marrow and bone. J Oral Surg 1980;38: Tatum, OH. Maxillary and sinus implant reconstruction. Dental Clinics of North America 1986;30: Summers, R. The osteotome technique: Part 3 Less invasive methods of elevating the sinus floor. Compend Contin Educ Dent 1994;15: Summers, R. The osteotome technique: Part 4 Future site development. Compend Contin Educ Dent 1995;16: Smiler DG. The sinus lift graft: Basic techniques and variations. Pract Periodont Aesthet Dent 1997;9(8): Jensen, O.T., Shulman, L.B., Block, M.S. & Iacono, V.J. Report of the Sinus Consensus Conference of International Journal of Oral & Maxillofacial Implants 1998;13 (Suppl.): Garg AK, Quinones CR. Augmentation of the maxillary sinus: A surgical technique. Pract Periodont Aesthet Dent 1997;9(2): ten Bruggenkate CM, van den Bergh JPA. Maxillary sinus floor elevation: A valuable preprosthetic procedure. Periodontol ;17: Thor A, Sennerby L, Hirsch J-M, Rasmusson L. Bone formation at the maxillary sinus floor following simultaneous elevation of the mucosal lining and implant installation without graft material an evaluation of 20 patients treated with 44 Astra Tech implants. J Oral Maxillofac Surg 2007;7(Suppl 1): Wallace SS, Froum SJ. Effect of maxillary sinus augmentation on the survival of endosseous dental implants. A systematic review. Ann Periodontol 2003;8: Del Fabbro M, Testori T, Francetti L, Weinstein R. Systematic review of survival rates for implants placed in the grafted maxillary sinus. Int J Periodontics Restorative Dent 2004;24: M. Staged sinus augmentation using a crestal core elevation procedure (CCE) to minimize membrane perforation. Pract Proced Aesthet Dent 2002;14: Peleg M, Sawatari Y. Sinus Floor Augmentation With Simultaneous Implant Placement in the Severely Atrophic Posterior Maxilla J Oral Maxillofac Surg 2007;65(9)Supp 1: Rosen PS, Summers R, Mellado JR, Salkin LM, Shanaman RH, Marks MH. The bone-added osteotome sinus floor elevation technique: Multicenter retrospective report of consecutively treated patients. Int J Oral Maxillofac Implants 1999;14: , M. Osteotome-mediated sinus floor elevation: A clinical report. Int J Oral Maxillofac Implants 2004;19: Conclusion The author presently uses the CCE procedure as a less invasive alternative to the lateral window osteotomy (LWO) for staged sinus floor elevation at sites where the ridge width is 7mm or more and the RSBH is 3mm to 6mm. Unlike SFE using a lateral approach, the extent of SFE facilitated by core intrusion is usually limited by the height of the preexisting crestal bone unless the core(s) are intruded well beyond the level of the original sinus floor which increases the risk of membrane laceration; therefore, CCE is contraindicated at sites where there is less than 3 mm of RSBH or ridge width does not permit core preparation. In these instances the author routinely utilizes and recommends a lateral approach. Correspondence: Dr. Michael 116 Central Park South, Suite 3 New York, NY mtoffler@earthlink.net 16. Ferrigno N, Laureti M, Fanali S. Dental implants placed in conjunction with osteotome sinus floor elevation: a 12-year life-table analysis from a prospective study on 588 ITI implants. Clin Oral Impl Res 2006;17: M. Site development in the posterior maxilla using osteocompression and apical alveolar displacement. Compend Contin Educ Dent 2001;22: Fugazzotto PA. The modified trephine/ osteotome sinus augmentation technique: Technical considerations and discussion of indications. Implant Dent 2001;10: Zubery Y, Nir E, Goldlust A. Ossification of a collagen membrane cross-linked by sugar: A human case series. J Periodontol 2008;79: M. Minimally invasive sinus floor elevation procedures for simultaneous and staged implant placement. New York State Dent J 2004;Nov: Mazor Z, Peleg M, Gross M. 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