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Int. J. Oral Maxillofac. Surg. 2015; xxx: xxx–xxx http://dx.doi.org/10.1016/j.ijom.2015.01.028, available online at http://www.sciencedirect.com
Clinical Paper Dental Implants
Sinus floor elevation with a crestal approach using a pressfit bone block: a case series
M. Isidori1, C. Genty2, S. David-Tchouda3,4, T. Fortin5 1 Implant Dentistry, Hospices Civils de Lyon, Lyon, France; 2Investigation Clinical Centre of Grenoble, INSERM, Grenoble, France; 3 Medico-economic Evaluation Unit, University Hospital of Grenoble, Grenoble, France; 4 ThEMAS TIMC UMR CNRS 5525, Grenoble Joseph Fourier University, Grenoble, France; 5 Department of Oral Surgery, Dental University of Lyon, University Claude Bernard, Lyon, France
M. Isidori, C. Genty, S. David-Tchouda, T. Fortin: Sinus floor elevation with a crestal approach using a press-fit bone block: a case series. Int. J. Oral Maxillofac. Surg. 2015; xxx: xxx–xxx. # 2015 Published by Elsevier Ltd on behalf of International Association of Oral and Maxillofacial Surgeons.
Abstract. This prospective study aimed to provide detailed clinical information on a sinus augmentation procedure, i.e., transcrestal sinus floor elevation with a bone block using the press-fit technique. A bone block is harvested with a trephine burr to obtain a cylinder. This block is inserted into the antrum via a crestal approach after creation of a circular crestal window. Thirty-three patients were treated with a fixed prosthesis supported by implants placed on 70 cylindrical bone blocks. The mean bone augmentation was 6.08 2.87 mm, ranging from 0 to 12.7 mm. Only one graft failed before implant placement. During surgery and the subsequent observation period, no complications were recorded, one implant was lost, and no infection or inflammation was observed. This proof-of-concept study suggests that the use of a bone block inserted into the sinus cavity via a crestal approach can be an alternative to the sinus lift procedure with the creation of a lateral window. It reduces the duration of surgery, cost of treatment, and overall discomfort.
In resorbed posterior maxillary bone due to alveolar ridge resorption and maxillary sinus pneumatization, implant placement posterior to the first premolar requires bone grafting, a procedure that is welldocumented in the literature.1,2 Following the creation of a window in the buccal side of the sinus, the Schneiderian membrane is elevated prior to bone placement to increase bone volume. The sinus augmentation procedure is associated with several complications.3 Membrane perforation is the most frequently reported complication, ranging from 0% to 58%, whether or not associated with sinusitis, which 0901-5027/000001+08
varies in severity.4 Graft loss also has to be considered a complication, since it modifies the treatment plan. Partial loss could modify implant placement, which could result in treatment failure related to aesthetics or function. Partial graft loss is found in 0–25% of cases, while total graft loss occurs in up to 2.6% of cases. This graft loss can be explained in part by biological concepts. It has been demonstrated that subantral bone can be augmented in a space created concentrically from the sinus bone walls after placement of the blood clot with or without the addition of filling materials. Thus, to
Key words: sinus floor elevation; atrophy; bone graft; oral implants; maxillary sinus augmentation; bone block; autogenous; allograft; minimally invasive. Accepted for publication 28 January 2015
optimize the bone-forming capacity of the subantral tissues, it is important to preserve the osteogenic potential from the lateral bone walls and to make the lateral window as small and as high as possible.4 This biological concept may be in contradiction with sufficient visual control in areas that are difficult to access through a lateral window. Thus, the design of the lateral window is a potential cause of graft loss. Whatever the design of the window, success can be described as the complete reossification of the reconstructive material based on osteogenic cell penetration,
# 2015 Published by Elsevier Ltd on behalf of International Association of Oral and Maxillofacial Surgeons.
Please cite this article in press as: Isidori M, et al. Sinus floor elevation with a crestal approach using a press-fit bone block: a case series, Int J Oral Maxillofac Surg (2015), http://dx.doi.org/10.1016/j.ijom.2015.01.028
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adhesion, and neovascularization to supply individual cells with nutrients and oxygen.5 The vascularization process continues over time in the host tissue, from the outer area to the core of the volume. Thus, the time required for the development of the vascular network to cover the entire graft volume depends on the grafted bone volume. As a consequence, cells located at the core of the graft die faster due to ischaemia in the central part, which can result in incomplete colonization,5,6 limited to the scaffold’s external layer or to some part of the scaffold, which does not permit appropriate implant placement. To counter this potential problem, particularly for severely atrophic bone in the posterior maxillary region that requires a greater volume of filling material, the use of image-guided surgery to take advantage of the limited remaining bone volume7 or the placement of zygomatic implants has been proposed.8 Another option would be to reduce the size of the grafted volume to the implant dimension at the implant location. Draenert and Eisenmenger9 have described such a surgical strategy: a transcrestal elevation of the sinus floor and alveolar ridge augmentation with a cylindrical bone transplant with the press-fit technique. This method also reduces the lateral fenestration of the maxillary sinus and the preparation of the sinus mucosa. The method was tested successfully on 10 fresh porcine skulls and two fresh human cadavers. To our knowledge no in vivo results have been published. The present prospective observational study was conducted to describe the clinical outcomes of this crestal approach with delayed implant placement. The objectives of this report are to describe potential graft complications and survival after a follow-up period of 2–13 years.
contacted early in 2012 for a follow-up visit. No patient was lost to follow-up. Patients were only recruited if they matched the following criteria: implant placement required to support a prosthesis; partially or totally edentulous maxilla associated with various degrees of alveolar ridge resorption and sinus pneumatization that did not allow the placement of adequately sized implants; age over 18 years. Exclusion criteria were as follows: the need for tooth extraction during the surgical procedure; signs of sinusitis recorded on the computed tomography (CT) scan; pregnancy at the time of evaluation; tobacco addiction, metabolic disorders, immunocompromised status, haemophilia or other bleeding disorders, drug or alcohol abuse, treatment with steroids, history of radiation therapy in the head and neck, psychiatric disorders, and inability to understand the procedure described. Surgical procedure
Surgical instruments
Two trephine burrs (Zepf; Helmut Zepf GmbH, Tuttlingen, Medizintechnik Germany) were used for the procedure; for example, a larger 6-mm (inner diameter) burr for donor site drilling and a smaller 5.5-mm (outer diameter) burr for crest drilling. An associated bone socket former with a tapered shape, a smooth tip, and a maximum outer diameter of 5.5 mm was used. For all bone graft material used, bone was harvested with the larger trephine burr in order to obtain a cylinder of bone of a certain diameter depending on the dimension of the residual crest and the planned implant diameter. The cylinder diameter was required to be 2 mm more than the planned implant diameter and the
length ideally greater than the planned implant length. Donor site
Autogenous bone or allograft bone (TBF Genie Tissulaire, Mions, France) was used. The choice was made by the practitioner, taking into consideration the amount of bone needed for appropriate reconstruction and patient compliance. Given the difficulty in harvesting large bone cylinders measuring 12 mm in length and 6 mm in diameter to place an implant 10 mm in length and 4 mm in diameter in one piece, allograft material was our first choice (Fig. 1). Autogenous graft material was harvested upon patient request or for a small block. Two sites were selected, the ramus and symphysis. For the ramus, after incision, we used a 6-mm inner diameter trephine burr mounted on a contra-angle under extensive saline irrigation. Sometimes the length of the cylinder was nearly 10 mm, other times it measured 6–8 mm (proximity of the dental alveolar nerve); in this case, two ramus bone cylinders were harvested in order to reconstruct a 10-mmhigh cylinder. We closed the site as for third molar surgical extraction. A similar procedure was used when harvesting on an edentulous span. For symphysis access, a 1-mm incision was made under the mucogingival line, generally half thickness for 5 mm and then full thickness, and the symphysis area exposed. The bone cylinder was removed carefully with the trephine, avoiding the incisors and the canine apex. The osseous holes could be filled with collagen sponge. Soft tissues were replaced and sutured. Preparation of the allogeneic bone graft is simple: the trephine corresponding to the inner diameter of the graft site is used
Materials and methods
Since 1998 we have performed the surgical approach presented herein as an alternative to the sinus lift with a lateral approach. Not every patient who matched the inclusion criteria was included, since very few patients were initially eligible until the follow-up observation period was considered sufficient to reuse the method. Surgery and associated data were recorded in a dedicated file at the time of surgery. For this reason the study can be considered a prospective case series. The files of all patients treated with the tested method in our department between 1998 and 2010 were screened thoroughly. All patients included in this study were
Fig. 1. Cylindrical corticocancellous allograft bone block (left arrow) used as graft material for sinus floor elevation. Bone was harvested using a trephine burr (right arrow).
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to manufacture a cylinder of allogeneic cancellous graft that perfectly fits the grafted site. Before drilling, it is important to moisten the osseous block with physiological serum. Crestal sinus floor elevation and bone augmentation procedure
One surgeon performed all the surgical procedures. Antibiotic prophylaxis was administered to all patients (amoxicillin 500 mg or clindamycin 300 mg) starting the day of surgery and continuing for 6 days after surgery. Steroids at 40 mg per day for 4 days were also administered. All patients were treated under local anaesthesia. A full-thickness flap was reflected to expose the top of the alveolar crest and a very limited amount of the buccal plate and the palatal curvature. The osteotomy was performed on the crest at the planned implant location using the 5.5-mm outer diameter trephine burrs mounted on a contra-angle under extensive saline irrigation. The drilling sequence was stopped 2 mm above the Schneiderian membrane and continued carefully with a bone socket former to preserve membrane integrity and to create a circular bone window (Fig. 2). The bone thickness was assessed before surgery by radiological examination (Fig. 3). The previously harvested bone cylinder was prepared with a conical shape and inserted until the top was approximately flush with the top of the crest. The conical shape in combination with the 0.5-mm underdrilled host site led to bone compression and improved the primary stability of the block. The top was then modelled to obtain a slight overcorrection of the crest. None of the blocks was attached with microscrews; particulate bone was never used to pack the recipient site, nor was a sheet used to cover the surgical site. Soft tissue management ensured tight flap closure with 3-0 silk or polyethylene sutures. This suture material was removed after 1 week. Postoperative instructions included mouth rinse (0.2% chlorhexidine) and paracetamol for analgesia.
Fig. 2. A cylindrical bone window is created with a trephine burr at the top of the crest (black arrow). The cylindrical bone block is inserted through the bone window (red arrow). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of the article.)
to increase the recipient site dimension in order to place a longer or larger implant (Fig. 4). Abutment connection and prosthetic loading of implants were performed 4 months after implant placement (Fig. 5).
Radiographic follow-up consisted of either panoramic or intraoral radiographs obtained immediately after the reconstructive procedure at the time of implant placement, at the time of prosthetic loading, and
Implant placement
After the healing period, a second-stage surgery was performed to place the endosseous implant. To ensure the placement of the implant within the bone block, two procedures were used: (1) an intraoperative X-ray was taken with the first burr in place, or (2) placement was imageguided.7 In some cases, the Summers technique was used at the time of placement
Fig. 3. CT scan before implant placement. Crestal bone thickness and width were assessed based on a CT scan before implant placement.
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annually thereafter (Fig. 6). In some cases, the bone gain was assessed before implant placement using CT (Fig. 7). Success criteria and data recorded
Control visits were conducted by a single surgeon in early 2012. Ethical approval was obtained to collect and analyze the data. During the follow-up visit, the prostheses were not removed because most were cemented. Implant survival was evaluated according to the clinical and radiological criteria proposed by Buser et al.10 and modified as follows: absence of mobility in prosthodontics, absence of peri-implant suppuration, absence of continuous radiolucency around the implant, and absence of pain and subjective sensation. Radiographic assessment
Crestal bone thickness and width were assessed based on a CT scan obtained before implant placement (Fig. 3). A line tangential to the bottom point of the crest was traced representing height zero. A line perpendicular to the zero line was traced passing through the bottom point. The distance between the intersection points of the perpendicular line with the first sinus point and with the zero line was used to calculate the residual bone height. A third line was traced parallel to the zero line passing through the above-mentioned first sinus intersection point. The distance between the first palatal point and the first buccal point on the third line was used to calculate the residual bone width. Bone height was measured before implant placement on an orthopantomogram (OPG) or intraoral X-rays to determine the bone gain. Intraoral X-rays were used to measure peri-implant bone loss, both at the marginal position and apex position. Radiographic assessment was carried out by a radiologist technician. For every patient, at every stage, radiography positioners were used, placing the bar parallel to the direction of the X-ray beam, perpendicular to the sensor. Marginal bone loss was measured based on the radiological criteria reported by Buser et al.,10 modified as follows: two reference points were marked on the surface of the implant platform and joined with a line representing height zero. Two vertical lines were drawn perpendicular to the zero line up to the first implant bone mesial and distal contact points. Differences in length between these perpendicular lines on X-rays taken at the different time points were
Fig. 4. At 4–6 months after the graft procedure, the recipient site is prepared for implant placement on the grafted bone block.
Fig. 5. Final abutments in place 4 months after implant placement.
Fig. 6. OPG with implants in place.
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with a mean of 194 days (detailed in Fig. 9). The follow-up after implant insertion ranged from 133 to 404 days, with a mean of 722 days. The follow-up after loading ranged from 390 to 4354 days, with a mean of 2173 days. The initial crestal bone widths varied from 3 to 16 mm, with a mean of 6.61 2.43 mm. The initial remaining bone height ranged from 0.5 to 11 mm, with a mean of 4.05 2.28 mm. Sixteen (20.8%) bone blocks were placed with a remaining bone height of less than 2 mm, 22 (28.6%) were placed with a remaining bone height of between 2 and 4 mm, 21 (27.3%) were placed with a remaining bone height of between 4 and 6 mm, and 18 (23.4%) with more than 6 mm of bone remaining.
Fig. 7. Bone gain before implant placement.
Success and survival criteria
No postoperative complications were observed. Only one graft failed before implant placement. All implants were placed at the planned location. Only one implant failed. This implant was placed in 2002 and failed in 2007. During the follow-up visit, no complications were reported according to the aforementioned criteria. The survival rate after 10 years was 97%; the Kaplan–Meier survival curve is shown in Fig. 10. Fig. 8. Marginal and apex bone loss was assessed on intraoral radiography: radiography at the control visit.
used to calculate bone loss. Bone loss was measured between implant placement and prosthesis placement, and between prosthesis placement and the control visit (Fig. 8). Results Patient data
From 1998 to 2010, 33 patients were treated; they ranged in age from 23 to 80 years (mean 55.5 years). All patients attended the follow-up visit in early 2012.
Seventy-seven cylindrical bone blocks were used for bone grafting for the placement of 70 implants. Twenty-seven patients were treated with an allograft bone block and six patients received an autogenous bone cylinder. Six blocks were not used for implant placement. They were placed close to another block to avoid the protrusion of only one block in the large sinus that could injure the membrane. One graft failed before implant placement (Table 1). The healing period before implant placement ranged from 56 to 423 days,
Bone augmentation before implant placement
Bone augmentation varied from 0 to with a mean of 12.7 mm, 6.08 2.87 mm. Figure 11 details the results and demonstrates the variation in bone gain when considering the initial bone height. The length of the implants placed ranged from 8 to 13 mm and the diameter ranged from 3.4 to 5 mm; 44.2% of the implants placed were 11 mm in length and 4.5 mm in diameter. When initial remaining bone was less than 2 mm, the implant placed ranged from 8 to 11 mm in length. When initial remaining bone ranged from 2 to 4 mm, the implant placed ranged from 8 to 13 mm.
Table 1. Lifetime analysis of implants placed on a cylinder graft. Year graft implanted 1998 2002 2003 2004 2007 2008 2009 2010 Total
Number of patients 1 4 2 1 1 2 14 8 33
Donor site
Number of implants placed
Chin 3 ramus, 1 allograft Allograft Chin Allograft Allograft Allograft 1 ramus, 7 allograft
1 11 4 1 2 6 25 20 70
Graft failure N N N N N N 1 N 1
Implant failure N 1 N N N N N N 1
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Fig. 9. Duration of graft healing before implant placement (n = 32 patients).
At the follow-up visit, we noted whether or not the implant protruded within the sinus. Twelve implants protruded within the sinus. Of these 12 implants, 10 were placed with a length greater than the initial bone block length and with an additional Summers technique.11,12 One implant was placed with a shorter length and one with a length similar to the bone block. The intraoral X-rays showed bone above the other 58 implant apices. Of these, 26 were placed with a length greater than the initial bone block length and with an additional Summers technique.11,13 Nineteen implants were placed with a shorter length and 13 with a length similar to the bone block. To summarize, 36 implants were placed with a length greater than the bone block; bone was found above the apex in 26 implants. Fourteen implants were placed of the same length as the bone block; bone was found above the apex in 13 implants. Twenty implants were placed with a length shorter than the bone block; bone was found above the apex in 19 implants. Discussion
Fig. 10. Kaplan–Meier survival curve.
When initial remaining bone was more than 4 mm, the implant placed ranged from 9.5 to 13 mm. Bone loss
Peri-implant bone loss between implant placement and loading at the crestal level
was radiologically null in 75% of the cases. The loss of bone at the crestal level between the loading stage and the followup day ranged from 0 to 4 mm, with a mean of 0.61 mm. In 64.7% of the cases, no bone loss was detectable radiologically. Table 2 details the mean changes around the implant shoulder.
Fig. 11. Bone augmentation in relation to the residual bone height (n = 75 bone blocks).
The observation period of this study may appear to be very long; this is because very few patients were initially eligible until the follow-up observation period was considered sufficient to reuse this method. This case series demonstrates that maxillary sinus floor elevation with cylinder bone blocks via the crestal approach, as described by Draenert and Eisenmenger,9 can be considered predictable and allows implant placement in the resorbed posterior maxilla. Only one graft failed before implant placement and no complications were clinically detectable during the follow-up visit. Clinical studies have shown that bone loss around the implant occurs primarily between implant placement and loading, which could be related to surgical trauma and the compromise of the crestal bone vascular supply after elevation of the mucoperiosteal flap and the interruption of the blood vessels caused by the osteotomy preparation. Bone loss after loading is related to the biological width dimension.12 A mean crestal bone loss of about 1 mm around the implant is generally found between implant placement and uncovering, ranging from 0.9 to 1.6 mm after the first year of function for the twostage implant14; an average 0.1–0.2 mm loss per year after this is considered acceptable. Thus we can state that bone loss is not an adverse event of the approach presented (Fig. 12).
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Sinus augmentation using press-fit bone block Table 2. Mean bone loss around the implant. Time since placement, years
Bone loss, average mm
Number of implants placed
0.45 0.44 0 0.5
20 25 6 2
0.6 1.25 1.56
1 4 11
0.5
1
2 3 4 5 6 7 8 9 10 11 12 13
At the tip, two implants protruded within the sinus due to bony resorption. The other 10 implants that protruded within the sinus where placed with a length greater than the bone block using the Summers technique. Therefore, it is quite difficult to know whether or not protrusion was due to bony resorption. However, Lambert et al.15 have reported preclinical studies that demonstrate resorption of regenerate bone by re-expansion of the sinus as a result of the positive air pressure inside the sinus associated with nasal breathing. Therefore, our results do not seem to be an adverse event of the technique. Currently described complications of the sinus augmentation procedure such as membrane perforation, infection, and graft loss,3 did not occur in the patients followed up in this study. Compared to the lateral approach, the crestal procedure seems less invasive, particularly when using an autogenous bone graft, which remains the benchmark of bone repair. Indeed, our experience shows that bony cylinders are more easily harvested locally, in the posterior part of the mandible for example, compared with rectangular bone blocks from either the intra- or extraoral surgical field.
Another aspect of this method is the use of a small volume of graft bone. Reduction of the graft volume may render cell penetration and adhesion within the entire scaffold more effective. Indeed, the vascularization process continues over time in the host tissue, from the outer to the whole construct.5 As a result, for a large edentulous span associated with severe bone atrophy, cell colonization may be limited to the scaffold’s external layers or to a part of the scaffold. This may not be sufficient to place the implant or this could lead to the placement of the implant in an unsuitable prosthetic location. Another valuable observation of this case series is the use of allogeneic bone blocks in 27 patients, confirming that allogeneic grafts provide predictable results.16,17 This crestal approach could be compared with the Summers technique.11,13 A review of the literature reported by Chiapasco et al.18 showed that the majority of publications suggest sinus floor elevation with a bone socket former when the residual bone height is 8 mm, to provide primary stability to the implant. With the surgical approach presented here, the mean residual bone thickness was 4.05 mm and almost
Fig. 12. Mean bone loss around the implant compared with bone loss generally found.15
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half the patients had less than 4 mm of remaining bone before the grafting procedure. When remaining bone was less than 2 mm, the augmentation ranged from 6.3 to 12.2 mm. When remaining bone ranged from 2 to 4 mm, the augmentation ranged from 4 to 12.7 mm. This much augmentation cannot be expected with the Summers technique. More recently, 4 mm of remaining bone combined with a short implant has been suggested with the Summers technique.19 Using a trephine burr combined with an osteotome and simultaneous short implant placement, residual bone height ranging from 0.96 to 4.96 mm can be sufficient, with a bone gain of 5.38 mm after surgery.20 In the procedure described in this paper, only two implants of 8 mm in length were used. Consequently, the indications for the method presented do not overlap with those of the Summers technique. On the contrary, we argue that the Summers technique can complete this approach. Indeed 50 of the 70 implants were placed with the same or greater length to the bone block used, with a bone socket former. The use of an antral balloon for sinus floor elevation and grafting has recently been proposed.21 This procedure permits an average bone gain of 7.5 mm, ranging from 5.2 to 10.5 mm. This confirms the results of different studies,22,23 even with limited bone height of 2–6 mm below the sinus floor. Even though there is a lack of long-term follow-up with this approach and no information on the indication, particularly regarding the inner anatomy of the sinus, every author states the short learning curve compared to previously described procedures. One should also mention the hydraulic pressure technique via a crestal approach to lift the Schneiderian membrane.24 The press-fit bone block procedure offers the advantage of properly checking the integrity of the membrane. Indeed in contrast to the aforementioned modified Summers technique and other innovative techniques that simultaneously fill the subantral space with particulate biomaterial for bone regeneration, the graft cannot dislodge into the free sinus cavity. This can be seen as a clear clinical advantage. This case series indicates that the use of a cylindrical bone block inserted into the antrum with a crestal approach may be an alternative to conventional sinus grafting. Further studies should confirm the exact indications for this procedure, particularly regarding the degree of atrophy. It would be useful to compare it with zygomatic implants.
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Funding
No funding. Competing interests
No competing interests. Ethical approval
Ethical approval to collect and analyze the data was obtained from the CECIC Rhoˆne–Alpes–Auvergne, Clermont-Ferrand (IRB 5891; 30 May 2014). Patient consent
Patient consent was obtained before any intervention. References 1. Boyne P, James RA. Grafting of the maxillary sinus floor with autogenous marrow and bone. Int J Oral Maxillofac Surg 1980; 38:113–6. 2. Wood R, Moore D. Grafting of the maxillary sinus with intraorally harvested autogenous bone prior to implant placement. Int J Oral Maxillofac Implants 1988;3:149–214. 3. Nkenke E, Stelzle F. Clinical outcomes of sinus floor augmentation for implant placement using autogenous bone or bone substitutes: a systematic review. Clin Oral Implants Res 2009;20(Suppl. 4):124–33. http://dx.doi.org/10.1111/j.16000501.2009.01776.x. 4. Barone A, Santini S, Sbordone L, Crespi R, Covani U. A clinical study of the outcomes and complications associated with maxillary sinus augmentation. Int J Oral Maxillofac Implants 2006;21:81–5. 5. Ko H, Milthorpe B, McFaulard CD. Engineering thick tissues—the vascularization problem. Eur Cell Matter 2007;14:1–18. 6. Becquart P, Cambon-Binder A, Monfoulet L, Bourguignon M, Vandamne K, Bensidhoum M, et al. Ischemia is the prime but not the only cause of human multipotent stromal cell death in tissue-engineered constructs in vivo. Tissue Eng Part A 2012;18:2084–94.
7. Fortin T, Isidori M, Bouchet H. Placement of posterior maxillary implants in partially edentulous patients with severe bone deficiency using CAD/CAM guidance to avoid sinus grafting: a clinical report of procedure. Int J Oral Maxillofac Implants 2009;24: 96–102. 8. Bothur S, Kindberg H, Lindqvist J. The positions of implant heads in relation to the fixed dental prosthesis: a comparison of multiple zygomatic implants with standard implants for the reconstruction of the atrophic maxilla. Int J Oral Maxillofac Implants 2012;27:664–70. 9. Draenert GF, Eisenmenger W. A new technique for the transcrestal sinus floor elevation and alveolar ridge augmentation with press-fit bone cylinders: a technical note. JCraniomaxillofac Surg 2007;35:201–6. 10. Buser D, Belser UC, Lang NP. The original one-stage dental implant system and its clinical application. Periodontol 2000 1998;17: 106–18. 11. Summers RS. The osteotome technique: Part 3—less invasive methods of elevating the sinus floor. Compendium 1994;15:698–708. 12. Weber HP, Buser D, Fiorellini JP, Williams RC. Radiographic evaluation of crestal bone levels adjacent to nonsubmerged titanium implants. Clin Oral Implants Res 1992;3: 181–8. 13. Summers RS. A new concept in maxillary implant surgery: the osteotome technique. Compendium 1994;15:152–60. 14. Fiorellini JP, Buser D, Paquette DW, William RC, Haghighi D, Weber HP. A radiographic evaluation of healing around submerged and non-submerged implants in beagle dogs. J Periodontol 1999;70:248–54. 15. Lambert F, Lecloux G, Rompen E. One-step approach for implant placement and subantral bone regeneration using bovine hydroxyapatite: a 2- to 6-year follow-up study. Int J Oral Maxillofac Implants 2010;25:598–606. 16. Nissan J, Ghelfan O, Mardinger O, Calderon S, Chaushu G. Efficacy of cancellous block allograft augmentation prior to implant placement in the posterior atrophic mandible. Clin Implant Dent Relat Res 2011;13:279–85. http://dx.doi.org/10.1111/ j. 1708-8208.2009.00219.x.
17. Guerrero JS, Al-Jandan BA. Allograft for maxillary sinus floor augmentation: a retrospective study of 90 cases. Implant Dent 2012;21:136–40. http://dx.doi.org/10.1097/ ID.0b013e31824a023b. 18. Chiapasco M, Zaniboni M, Boisco M. Augmentation procedures for the rehabilitation of deficient edentulous ridges with oral implants. Clin Oral Implants Res 2006; 17(Suppl 2):136–59. 19. Ca˘lin C, Petre A, Drafta S. Osteotome-mediated sinus floor elevation: a systematic review and meta-analysis. Int J Oral Maxillofac Implants 2014;29:558–76. 20. Teng M, Liang X, Yuan Q, Nie J, Ye J, Cheng Q, et al. The inlay osteotome sinus augmentation technique for placing short implants simultaneously with reduced crestal bone height. A short-term follow-up. Clin Implant Dent Relat Res 2013;15:918–26. 21. Rao GS, Reddy SK. Antral balloon sinus elevation and grafting prior to dental implant placement: review of 34 cases. Int J Oral Maxillofac Implants 2014;29:414–8. 22. Mazor Z, Kfir E, Lorean A, Mijiritsky E, Horowitz RA. Flapless approach to maxillary sinus augmentation using minimally invasive antral membrane balloon elevation. Implant Dent 2011;20:434–8. 23. Petruzzi M, Ceccarelli R, Testori T, Grassi FR. Sinus floor augmentation with a hydropneumatic technique: a retrospective study in 40 patients. Int J Periodontics Restorative Dent 2012;32:205–10. 24. Lopez MA, Bassi MA, Confalone L, Carinci F. Maxillary sinus floor elevation via crestal approach: the evolution of the hydraulic pressure technique. J Craniofac Surg 2014;25:e127–32.
Address: Thomas Fortin Department of Oral Surgery School of Dentistry University Claude Bernard Lyon 1 Rue Guillaume Paradin 69003 Lyon France Tel: +33 4 74 93 41 41 E-mail: [email protected]
Please cite this article in press as: Isidori M, et al. Sinus floor elevation with a crestal approach using a press-fit bone block: a case series, Int J Oral Maxillofac Surg (2015), http://dx.doi.org/10.1016/j.ijom.2015.01.028
Int. J. Oral Maxillofac. Surg. 2015; xxx: xxx–xxx http://dx.doi.org/10.1016/j.ijom.2015.01.028, available online at http://www.sciencedirect.com
Clinical Paper Dental Implants
Sinus floor elevation with a crestal approach using a pressfit bone block: a case series
M. Isidori1, C. Genty2, S. David-Tchouda3,4, T. Fortin5 1 Implant Dentistry, Hospices Civils de Lyon, Lyon, France; 2Investigation Clinical Centre of Grenoble, INSERM, Grenoble, France; 3 Medico-economic Evaluation Unit, University Hospital of Grenoble, Grenoble, France; 4 ThEMAS TIMC UMR CNRS 5525, Grenoble Joseph Fourier University, Grenoble, France; 5 Department of Oral Surgery, Dental University of Lyon, University Claude Bernard, Lyon, France
M. Isidori, C. Genty, S. David-Tchouda, T. Fortin: Sinus floor elevation with a crestal approach using a press-fit bone block: a case series. Int. J. Oral Maxillofac. Surg. 2015; xxx: xxx–xxx. # 2015 Published by Elsevier Ltd on behalf of International Association of Oral and Maxillofacial Surgeons.
Abstract. This prospective study aimed to provide detailed clinical information on a sinus augmentation procedure, i.e., transcrestal sinus floor elevation with a bone block using the press-fit technique. A bone block is harvested with a trephine burr to obtain a cylinder. This block is inserted into the antrum via a crestal approach after creation of a circular crestal window. Thirty-three patients were treated with a fixed prosthesis supported by implants placed on 70 cylindrical bone blocks. The mean bone augmentation was 6.08 2.87 mm, ranging from 0 to 12.7 mm. Only one graft failed before implant placement. During surgery and the subsequent observation period, no complications were recorded, one implant was lost, and no infection or inflammation was observed. This proof-of-concept study suggests that the use of a bone block inserted into the sinus cavity via a crestal approach can be an alternative to the sinus lift procedure with the creation of a lateral window. It reduces the duration of surgery, cost of treatment, and overall discomfort.
In resorbed posterior maxillary bone due to alveolar ridge resorption and maxillary sinus pneumatization, implant placement posterior to the first premolar requires bone grafting, a procedure that is welldocumented in the literature.1,2 Following the creation of a window in the buccal side of the sinus, the Schneiderian membrane is elevated prior to bone placement to increase bone volume. The sinus augmentation procedure is associated with several complications.3 Membrane perforation is the most frequently reported complication, ranging from 0% to 58%, whether or not associated with sinusitis, which 0901-5027/000001+08
varies in severity.4 Graft loss also has to be considered a complication, since it modifies the treatment plan. Partial loss could modify implant placement, which could result in treatment failure related to aesthetics or function. Partial graft loss is found in 0–25% of cases, while total graft loss occurs in up to 2.6% of cases. This graft loss can be explained in part by biological concepts. It has been demonstrated that subantral bone can be augmented in a space created concentrically from the sinus bone walls after placement of the blood clot with or without the addition of filling materials. Thus, to
Key words: sinus floor elevation; atrophy; bone graft; oral implants; maxillary sinus augmentation; bone block; autogenous; allograft; minimally invasive. Accepted for publication 28 January 2015
optimize the bone-forming capacity of the subantral tissues, it is important to preserve the osteogenic potential from the lateral bone walls and to make the lateral window as small and as high as possible.4 This biological concept may be in contradiction with sufficient visual control in areas that are difficult to access through a lateral window. Thus, the design of the lateral window is a potential cause of graft loss. Whatever the design of the window, success can be described as the complete reossification of the reconstructive material based on osteogenic cell penetration,
# 2015 Published by Elsevier Ltd on behalf of International Association of Oral and Maxillofacial Surgeons.
Please cite this article in press as: Isidori M, et al. Sinus floor elevation with a crestal approach using a press-fit bone block: a case series, Int J Oral Maxillofac Surg (2015), http://dx.doi.org/10.1016/j.ijom.2015.01.028
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adhesion, and neovascularization to supply individual cells with nutrients and oxygen.5 The vascularization process continues over time in the host tissue, from the outer area to the core of the volume. Thus, the time required for the development of the vascular network to cover the entire graft volume depends on the grafted bone volume. As a consequence, cells located at the core of the graft die faster due to ischaemia in the central part, which can result in incomplete colonization,5,6 limited to the scaffold’s external layer or to some part of the scaffold, which does not permit appropriate implant placement. To counter this potential problem, particularly for severely atrophic bone in the posterior maxillary region that requires a greater volume of filling material, the use of image-guided surgery to take advantage of the limited remaining bone volume7 or the placement of zygomatic implants has been proposed.8 Another option would be to reduce the size of the grafted volume to the implant dimension at the implant location. Draenert and Eisenmenger9 have described such a surgical strategy: a transcrestal elevation of the sinus floor and alveolar ridge augmentation with a cylindrical bone transplant with the press-fit technique. This method also reduces the lateral fenestration of the maxillary sinus and the preparation of the sinus mucosa. The method was tested successfully on 10 fresh porcine skulls and two fresh human cadavers. To our knowledge no in vivo results have been published. The present prospective observational study was conducted to describe the clinical outcomes of this crestal approach with delayed implant placement. The objectives of this report are to describe potential graft complications and survival after a follow-up period of 2–13 years.
contacted early in 2012 for a follow-up visit. No patient was lost to follow-up. Patients were only recruited if they matched the following criteria: implant placement required to support a prosthesis; partially or totally edentulous maxilla associated with various degrees of alveolar ridge resorption and sinus pneumatization that did not allow the placement of adequately sized implants; age over 18 years. Exclusion criteria were as follows: the need for tooth extraction during the surgical procedure; signs of sinusitis recorded on the computed tomography (CT) scan; pregnancy at the time of evaluation; tobacco addiction, metabolic disorders, immunocompromised status, haemophilia or other bleeding disorders, drug or alcohol abuse, treatment with steroids, history of radiation therapy in the head and neck, psychiatric disorders, and inability to understand the procedure described. Surgical procedure
Surgical instruments
Two trephine burrs (Zepf; Helmut Zepf GmbH, Tuttlingen, Medizintechnik Germany) were used for the procedure; for example, a larger 6-mm (inner diameter) burr for donor site drilling and a smaller 5.5-mm (outer diameter) burr for crest drilling. An associated bone socket former with a tapered shape, a smooth tip, and a maximum outer diameter of 5.5 mm was used. For all bone graft material used, bone was harvested with the larger trephine burr in order to obtain a cylinder of bone of a certain diameter depending on the dimension of the residual crest and the planned implant diameter. The cylinder diameter was required to be 2 mm more than the planned implant diameter and the
length ideally greater than the planned implant length. Donor site
Autogenous bone or allograft bone (TBF Genie Tissulaire, Mions, France) was used. The choice was made by the practitioner, taking into consideration the amount of bone needed for appropriate reconstruction and patient compliance. Given the difficulty in harvesting large bone cylinders measuring 12 mm in length and 6 mm in diameter to place an implant 10 mm in length and 4 mm in diameter in one piece, allograft material was our first choice (Fig. 1). Autogenous graft material was harvested upon patient request or for a small block. Two sites were selected, the ramus and symphysis. For the ramus, after incision, we used a 6-mm inner diameter trephine burr mounted on a contra-angle under extensive saline irrigation. Sometimes the length of the cylinder was nearly 10 mm, other times it measured 6–8 mm (proximity of the dental alveolar nerve); in this case, two ramus bone cylinders were harvested in order to reconstruct a 10-mmhigh cylinder. We closed the site as for third molar surgical extraction. A similar procedure was used when harvesting on an edentulous span. For symphysis access, a 1-mm incision was made under the mucogingival line, generally half thickness for 5 mm and then full thickness, and the symphysis area exposed. The bone cylinder was removed carefully with the trephine, avoiding the incisors and the canine apex. The osseous holes could be filled with collagen sponge. Soft tissues were replaced and sutured. Preparation of the allogeneic bone graft is simple: the trephine corresponding to the inner diameter of the graft site is used
Materials and methods
Since 1998 we have performed the surgical approach presented herein as an alternative to the sinus lift with a lateral approach. Not every patient who matched the inclusion criteria was included, since very few patients were initially eligible until the follow-up observation period was considered sufficient to reuse the method. Surgery and associated data were recorded in a dedicated file at the time of surgery. For this reason the study can be considered a prospective case series. The files of all patients treated with the tested method in our department between 1998 and 2010 were screened thoroughly. All patients included in this study were
Fig. 1. Cylindrical corticocancellous allograft bone block (left arrow) used as graft material for sinus floor elevation. Bone was harvested using a trephine burr (right arrow).
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to manufacture a cylinder of allogeneic cancellous graft that perfectly fits the grafted site. Before drilling, it is important to moisten the osseous block with physiological serum. Crestal sinus floor elevation and bone augmentation procedure
One surgeon performed all the surgical procedures. Antibiotic prophylaxis was administered to all patients (amoxicillin 500 mg or clindamycin 300 mg) starting the day of surgery and continuing for 6 days after surgery. Steroids at 40 mg per day for 4 days were also administered. All patients were treated under local anaesthesia. A full-thickness flap was reflected to expose the top of the alveolar crest and a very limited amount of the buccal plate and the palatal curvature. The osteotomy was performed on the crest at the planned implant location using the 5.5-mm outer diameter trephine burrs mounted on a contra-angle under extensive saline irrigation. The drilling sequence was stopped 2 mm above the Schneiderian membrane and continued carefully with a bone socket former to preserve membrane integrity and to create a circular bone window (Fig. 2). The bone thickness was assessed before surgery by radiological examination (Fig. 3). The previously harvested bone cylinder was prepared with a conical shape and inserted until the top was approximately flush with the top of the crest. The conical shape in combination with the 0.5-mm underdrilled host site led to bone compression and improved the primary stability of the block. The top was then modelled to obtain a slight overcorrection of the crest. None of the blocks was attached with microscrews; particulate bone was never used to pack the recipient site, nor was a sheet used to cover the surgical site. Soft tissue management ensured tight flap closure with 3-0 silk or polyethylene sutures. This suture material was removed after 1 week. Postoperative instructions included mouth rinse (0.2% chlorhexidine) and paracetamol for analgesia.
Fig. 2. A cylindrical bone window is created with a trephine burr at the top of the crest (black arrow). The cylindrical bone block is inserted through the bone window (red arrow). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of the article.)
to increase the recipient site dimension in order to place a longer or larger implant (Fig. 4). Abutment connection and prosthetic loading of implants were performed 4 months after implant placement (Fig. 5).
Radiographic follow-up consisted of either panoramic or intraoral radiographs obtained immediately after the reconstructive procedure at the time of implant placement, at the time of prosthetic loading, and
Implant placement
After the healing period, a second-stage surgery was performed to place the endosseous implant. To ensure the placement of the implant within the bone block, two procedures were used: (1) an intraoperative X-ray was taken with the first burr in place, or (2) placement was imageguided.7 In some cases, the Summers technique was used at the time of placement
Fig. 3. CT scan before implant placement. Crestal bone thickness and width were assessed based on a CT scan before implant placement.
Please cite this article in press as: Isidori M, et al. Sinus floor elevation with a crestal approach using a press-fit bone block: a case series, Int J Oral Maxillofac Surg (2015), http://dx.doi.org/10.1016/j.ijom.2015.01.028
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annually thereafter (Fig. 6). In some cases, the bone gain was assessed before implant placement using CT (Fig. 7). Success criteria and data recorded
Control visits were conducted by a single surgeon in early 2012. Ethical approval was obtained to collect and analyze the data. During the follow-up visit, the prostheses were not removed because most were cemented. Implant survival was evaluated according to the clinical and radiological criteria proposed by Buser et al.10 and modified as follows: absence of mobility in prosthodontics, absence of peri-implant suppuration, absence of continuous radiolucency around the implant, and absence of pain and subjective sensation. Radiographic assessment
Crestal bone thickness and width were assessed based on a CT scan obtained before implant placement (Fig. 3). A line tangential to the bottom point of the crest was traced representing height zero. A line perpendicular to the zero line was traced passing through the bottom point. The distance between the intersection points of the perpendicular line with the first sinus point and with the zero line was used to calculate the residual bone height. A third line was traced parallel to the zero line passing through the above-mentioned first sinus intersection point. The distance between the first palatal point and the first buccal point on the third line was used to calculate the residual bone width. Bone height was measured before implant placement on an orthopantomogram (OPG) or intraoral X-rays to determine the bone gain. Intraoral X-rays were used to measure peri-implant bone loss, both at the marginal position and apex position. Radiographic assessment was carried out by a radiologist technician. For every patient, at every stage, radiography positioners were used, placing the bar parallel to the direction of the X-ray beam, perpendicular to the sensor. Marginal bone loss was measured based on the radiological criteria reported by Buser et al.,10 modified as follows: two reference points were marked on the surface of the implant platform and joined with a line representing height zero. Two vertical lines were drawn perpendicular to the zero line up to the first implant bone mesial and distal contact points. Differences in length between these perpendicular lines on X-rays taken at the different time points were
Fig. 4. At 4–6 months after the graft procedure, the recipient site is prepared for implant placement on the grafted bone block.
Fig. 5. Final abutments in place 4 months after implant placement.
Fig. 6. OPG with implants in place.
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with a mean of 194 days (detailed in Fig. 9). The follow-up after implant insertion ranged from 133 to 404 days, with a mean of 722 days. The follow-up after loading ranged from 390 to 4354 days, with a mean of 2173 days. The initial crestal bone widths varied from 3 to 16 mm, with a mean of 6.61 2.43 mm. The initial remaining bone height ranged from 0.5 to 11 mm, with a mean of 4.05 2.28 mm. Sixteen (20.8%) bone blocks were placed with a remaining bone height of less than 2 mm, 22 (28.6%) were placed with a remaining bone height of between 2 and 4 mm, 21 (27.3%) were placed with a remaining bone height of between 4 and 6 mm, and 18 (23.4%) with more than 6 mm of bone remaining.
Fig. 7. Bone gain before implant placement.
Success and survival criteria
No postoperative complications were observed. Only one graft failed before implant placement. All implants were placed at the planned location. Only one implant failed. This implant was placed in 2002 and failed in 2007. During the follow-up visit, no complications were reported according to the aforementioned criteria. The survival rate after 10 years was 97%; the Kaplan–Meier survival curve is shown in Fig. 10. Fig. 8. Marginal and apex bone loss was assessed on intraoral radiography: radiography at the control visit.
used to calculate bone loss. Bone loss was measured between implant placement and prosthesis placement, and between prosthesis placement and the control visit (Fig. 8). Results Patient data
From 1998 to 2010, 33 patients were treated; they ranged in age from 23 to 80 years (mean 55.5 years). All patients attended the follow-up visit in early 2012.
Seventy-seven cylindrical bone blocks were used for bone grafting for the placement of 70 implants. Twenty-seven patients were treated with an allograft bone block and six patients received an autogenous bone cylinder. Six blocks were not used for implant placement. They were placed close to another block to avoid the protrusion of only one block in the large sinus that could injure the membrane. One graft failed before implant placement (Table 1). The healing period before implant placement ranged from 56 to 423 days,
Bone augmentation before implant placement
Bone augmentation varied from 0 to with a mean of 12.7 mm, 6.08 2.87 mm. Figure 11 details the results and demonstrates the variation in bone gain when considering the initial bone height. The length of the implants placed ranged from 8 to 13 mm and the diameter ranged from 3.4 to 5 mm; 44.2% of the implants placed were 11 mm in length and 4.5 mm in diameter. When initial remaining bone was less than 2 mm, the implant placed ranged from 8 to 11 mm in length. When initial remaining bone ranged from 2 to 4 mm, the implant placed ranged from 8 to 13 mm.
Table 1. Lifetime analysis of implants placed on a cylinder graft. Year graft implanted 1998 2002 2003 2004 2007 2008 2009 2010 Total
Number of patients 1 4 2 1 1 2 14 8 33
Donor site
Number of implants placed
Chin 3 ramus, 1 allograft Allograft Chin Allograft Allograft Allograft 1 ramus, 7 allograft
1 11 4 1 2 6 25 20 70
Graft failure N N N N N N 1 N 1
Implant failure N 1 N N N N N N 1
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Fig. 9. Duration of graft healing before implant placement (n = 32 patients).
At the follow-up visit, we noted whether or not the implant protruded within the sinus. Twelve implants protruded within the sinus. Of these 12 implants, 10 were placed with a length greater than the initial bone block length and with an additional Summers technique.11,12 One implant was placed with a shorter length and one with a length similar to the bone block. The intraoral X-rays showed bone above the other 58 implant apices. Of these, 26 were placed with a length greater than the initial bone block length and with an additional Summers technique.11,13 Nineteen implants were placed with a shorter length and 13 with a length similar to the bone block. To summarize, 36 implants were placed with a length greater than the bone block; bone was found above the apex in 26 implants. Fourteen implants were placed of the same length as the bone block; bone was found above the apex in 13 implants. Twenty implants were placed with a length shorter than the bone block; bone was found above the apex in 19 implants. Discussion
Fig. 10. Kaplan–Meier survival curve.
When initial remaining bone was more than 4 mm, the implant placed ranged from 9.5 to 13 mm. Bone loss
Peri-implant bone loss between implant placement and loading at the crestal level
was radiologically null in 75% of the cases. The loss of bone at the crestal level between the loading stage and the followup day ranged from 0 to 4 mm, with a mean of 0.61 mm. In 64.7% of the cases, no bone loss was detectable radiologically. Table 2 details the mean changes around the implant shoulder.
Fig. 11. Bone augmentation in relation to the residual bone height (n = 75 bone blocks).
The observation period of this study may appear to be very long; this is because very few patients were initially eligible until the follow-up observation period was considered sufficient to reuse this method. This case series demonstrates that maxillary sinus floor elevation with cylinder bone blocks via the crestal approach, as described by Draenert and Eisenmenger,9 can be considered predictable and allows implant placement in the resorbed posterior maxilla. Only one graft failed before implant placement and no complications were clinically detectable during the follow-up visit. Clinical studies have shown that bone loss around the implant occurs primarily between implant placement and loading, which could be related to surgical trauma and the compromise of the crestal bone vascular supply after elevation of the mucoperiosteal flap and the interruption of the blood vessels caused by the osteotomy preparation. Bone loss after loading is related to the biological width dimension.12 A mean crestal bone loss of about 1 mm around the implant is generally found between implant placement and uncovering, ranging from 0.9 to 1.6 mm after the first year of function for the twostage implant14; an average 0.1–0.2 mm loss per year after this is considered acceptable. Thus we can state that bone loss is not an adverse event of the approach presented (Fig. 12).
Please cite this article in press as: Isidori M, et al. Sinus floor elevation with a crestal approach using a press-fit bone block: a case series, Int J Oral Maxillofac Surg (2015), http://dx.doi.org/10.1016/j.ijom.2015.01.028
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Sinus augmentation using press-fit bone block Table 2. Mean bone loss around the implant. Time since placement, years
Bone loss, average mm
Number of implants placed
0.45 0.44 0 0.5
20 25 6 2
0.6 1.25 1.56
1 4 11
0.5
1
2 3 4 5 6 7 8 9 10 11 12 13
At the tip, two implants protruded within the sinus due to bony resorption. The other 10 implants that protruded within the sinus where placed with a length greater than the bone block using the Summers technique. Therefore, it is quite difficult to know whether or not protrusion was due to bony resorption. However, Lambert et al.15 have reported preclinical studies that demonstrate resorption of regenerate bone by re-expansion of the sinus as a result of the positive air pressure inside the sinus associated with nasal breathing. Therefore, our results do not seem to be an adverse event of the technique. Currently described complications of the sinus augmentation procedure such as membrane perforation, infection, and graft loss,3 did not occur in the patients followed up in this study. Compared to the lateral approach, the crestal procedure seems less invasive, particularly when using an autogenous bone graft, which remains the benchmark of bone repair. Indeed, our experience shows that bony cylinders are more easily harvested locally, in the posterior part of the mandible for example, compared with rectangular bone blocks from either the intra- or extraoral surgical field.
Another aspect of this method is the use of a small volume of graft bone. Reduction of the graft volume may render cell penetration and adhesion within the entire scaffold more effective. Indeed, the vascularization process continues over time in the host tissue, from the outer to the whole construct.5 As a result, for a large edentulous span associated with severe bone atrophy, cell colonization may be limited to the scaffold’s external layers or to a part of the scaffold. This may not be sufficient to place the implant or this could lead to the placement of the implant in an unsuitable prosthetic location. Another valuable observation of this case series is the use of allogeneic bone blocks in 27 patients, confirming that allogeneic grafts provide predictable results.16,17 This crestal approach could be compared with the Summers technique.11,13 A review of the literature reported by Chiapasco et al.18 showed that the majority of publications suggest sinus floor elevation with a bone socket former when the residual bone height is 8 mm, to provide primary stability to the implant. With the surgical approach presented here, the mean residual bone thickness was 4.05 mm and almost
Fig. 12. Mean bone loss around the implant compared with bone loss generally found.15
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half the patients had less than 4 mm of remaining bone before the grafting procedure. When remaining bone was less than 2 mm, the augmentation ranged from 6.3 to 12.2 mm. When remaining bone ranged from 2 to 4 mm, the augmentation ranged from 4 to 12.7 mm. This much augmentation cannot be expected with the Summers technique. More recently, 4 mm of remaining bone combined with a short implant has been suggested with the Summers technique.19 Using a trephine burr combined with an osteotome and simultaneous short implant placement, residual bone height ranging from 0.96 to 4.96 mm can be sufficient, with a bone gain of 5.38 mm after surgery.20 In the procedure described in this paper, only two implants of 8 mm in length were used. Consequently, the indications for the method presented do not overlap with those of the Summers technique. On the contrary, we argue that the Summers technique can complete this approach. Indeed 50 of the 70 implants were placed with the same or greater length to the bone block used, with a bone socket former. The use of an antral balloon for sinus floor elevation and grafting has recently been proposed.21 This procedure permits an average bone gain of 7.5 mm, ranging from 5.2 to 10.5 mm. This confirms the results of different studies,22,23 even with limited bone height of 2–6 mm below the sinus floor. Even though there is a lack of long-term follow-up with this approach and no information on the indication, particularly regarding the inner anatomy of the sinus, every author states the short learning curve compared to previously described procedures. One should also mention the hydraulic pressure technique via a crestal approach to lift the Schneiderian membrane.24 The press-fit bone block procedure offers the advantage of properly checking the integrity of the membrane. Indeed in contrast to the aforementioned modified Summers technique and other innovative techniques that simultaneously fill the subantral space with particulate biomaterial for bone regeneration, the graft cannot dislodge into the free sinus cavity. This can be seen as a clear clinical advantage. This case series indicates that the use of a cylindrical bone block inserted into the antrum with a crestal approach may be an alternative to conventional sinus grafting. Further studies should confirm the exact indications for this procedure, particularly regarding the degree of atrophy. It would be useful to compare it with zygomatic implants.
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Funding
No funding. Competing interests
No competing interests. Ethical approval
Ethical approval to collect and analyze the data was obtained from the CECIC Rhoˆne–Alpes–Auvergne, Clermont-Ferrand (IRB 5891; 30 May 2014). Patient consent
Patient consent was obtained before any intervention. References 1. Boyne P, James RA. Grafting of the maxillary sinus floor with autogenous marrow and bone. Int J Oral Maxillofac Surg 1980; 38:113–6. 2. Wood R, Moore D. Grafting of the maxillary sinus with intraorally harvested autogenous bone prior to implant placement. Int J Oral Maxillofac Implants 1988;3:149–214. 3. Nkenke E, Stelzle F. Clinical outcomes of sinus floor augmentation for implant placement using autogenous bone or bone substitutes: a systematic review. Clin Oral Implants Res 2009;20(Suppl. 4):124–33. http://dx.doi.org/10.1111/j.16000501.2009.01776.x. 4. Barone A, Santini S, Sbordone L, Crespi R, Covani U. A clinical study of the outcomes and complications associated with maxillary sinus augmentation. Int J Oral Maxillofac Implants 2006;21:81–5. 5. Ko H, Milthorpe B, McFaulard CD. Engineering thick tissues—the vascularization problem. Eur Cell Matter 2007;14:1–18. 6. Becquart P, Cambon-Binder A, Monfoulet L, Bourguignon M, Vandamne K, Bensidhoum M, et al. Ischemia is the prime but not the only cause of human multipotent stromal cell death in tissue-engineered constructs in vivo. Tissue Eng Part A 2012;18:2084–94.
7. Fortin T, Isidori M, Bouchet H. Placement of posterior maxillary implants in partially edentulous patients with severe bone deficiency using CAD/CAM guidance to avoid sinus grafting: a clinical report of procedure. Int J Oral Maxillofac Implants 2009;24: 96–102. 8. Bothur S, Kindberg H, Lindqvist J. The positions of implant heads in relation to the fixed dental prosthesis: a comparison of multiple zygomatic implants with standard implants for the reconstruction of the atrophic maxilla. Int J Oral Maxillofac Implants 2012;27:664–70. 9. Draenert GF, Eisenmenger W. A new technique for the transcrestal sinus floor elevation and alveolar ridge augmentation with press-fit bone cylinders: a technical note. JCraniomaxillofac Surg 2007;35:201–6. 10. Buser D, Belser UC, Lang NP. The original one-stage dental implant system and its clinical application. Periodontol 2000 1998;17: 106–18. 11. Summers RS. The osteotome technique: Part 3—less invasive methods of elevating the sinus floor. Compendium 1994;15:698–708. 12. Weber HP, Buser D, Fiorellini JP, Williams RC. Radiographic evaluation of crestal bone levels adjacent to nonsubmerged titanium implants. Clin Oral Implants Res 1992;3: 181–8. 13. Summers RS. A new concept in maxillary implant surgery: the osteotome technique. Compendium 1994;15:152–60. 14. Fiorellini JP, Buser D, Paquette DW, William RC, Haghighi D, Weber HP. A radiographic evaluation of healing around submerged and non-submerged implants in beagle dogs. J Periodontol 1999;70:248–54. 15. Lambert F, Lecloux G, Rompen E. One-step approach for implant placement and subantral bone regeneration using bovine hydroxyapatite: a 2- to 6-year follow-up study. Int J Oral Maxillofac Implants 2010;25:598–606. 16. Nissan J, Ghelfan O, Mardinger O, Calderon S, Chaushu G. Efficacy of cancellous block allograft augmentation prior to implant placement in the posterior atrophic mandible. Clin Implant Dent Relat Res 2011;13:279–85. http://dx.doi.org/10.1111/ j. 1708-8208.2009.00219.x.
17. Guerrero JS, Al-Jandan BA. Allograft for maxillary sinus floor augmentation: a retrospective study of 90 cases. Implant Dent 2012;21:136–40. http://dx.doi.org/10.1097/ ID.0b013e31824a023b. 18. Chiapasco M, Zaniboni M, Boisco M. Augmentation procedures for the rehabilitation of deficient edentulous ridges with oral implants. Clin Oral Implants Res 2006; 17(Suppl 2):136–59. 19. Ca˘lin C, Petre A, Drafta S. Osteotome-mediated sinus floor elevation: a systematic review and meta-analysis. Int J Oral Maxillofac Implants 2014;29:558–76. 20. Teng M, Liang X, Yuan Q, Nie J, Ye J, Cheng Q, et al. The inlay osteotome sinus augmentation technique for placing short implants simultaneously with reduced crestal bone height. A short-term follow-up. Clin Implant Dent Relat Res 2013;15:918–26. 21. Rao GS, Reddy SK. Antral balloon sinus elevation and grafting prior to dental implant placement: review of 34 cases. Int J Oral Maxillofac Implants 2014;29:414–8. 22. Mazor Z, Kfir E, Lorean A, Mijiritsky E, Horowitz RA. Flapless approach to maxillary sinus augmentation using minimally invasive antral membrane balloon elevation. Implant Dent 2011;20:434–8. 23. Petruzzi M, Ceccarelli R, Testori T, Grassi FR. Sinus floor augmentation with a hydropneumatic technique: a retrospective study in 40 patients. Int J Periodontics Restorative Dent 2012;32:205–10. 24. Lopez MA, Bassi MA, Confalone L, Carinci F. Maxillary sinus floor elevation via crestal approach: the evolution of the hydraulic pressure technique. J Craniofac Surg 2014;25:e127–32.
Address: Thomas Fortin Department of Oral Surgery School of Dentistry University Claude Bernard Lyon 1 Rue Guillaume Paradin 69003 Lyon France Tel: +33 4 74 93 41 41 E-mail: [email protected]
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