ORIGINAL ARTICLE
Immediate Function of Partial Fixed Rehabilitation With Axial and Tilted Implants Having Intrasinus Insertion Enrico Luigi Agliardi, MD, DDS,* Stefano Tetè, MD, DDS,† Davide Romeo, DDS, PhD Luciano Malchiodi, MD, DDS,‡ and Enrico Gherlone, MD, DMD* Abstract: Implant-supported rehabilitation of the posterior maxilla could be challenging because hyperpneumatization of the maxillary sinus might reduce the bone height. In this study, the authors report preliminary results of a new treatment modality for the partial fixed rehabilitation of posterior maxilla with immediate function by using 1 anterior axial implant and 1 posterior tilted implant with intrasinus mesial insertion. From 2009 to 2011, 10 patients (6 women and 4 men) with missing upper premolars and molars were recruited and treated according to this protocol. Each patient received a partial fixed bridge supported by 1 axial anterior implant and 1 posterior implant placed with a 30-degree mesial inclination and intrasinus insertion. Autologous bone was positioned to fill the maxillary sinus cavity and to cover the exposed implant surface after elevation of the anterior sinus membrane. A prosthesis with immediate function was positioned within 3 hours, whereas a CAD/CAM final restoration was delivered 6 months later. Follow-ups at 6 and 12 months, and then annually, were scheduled. At each follow-up, plaque level and bleeding scores were assessed, and radiographic evaluation of marginal bone level change was performed at 1 year. The patients were followed up for a mean of 50 months (range, 42–57 mo). No implants were lost, and all prostheses were stable and functional, reporting 100% of implant and prosthetic success rates. After 1 year, bone loss had a mean (SD) of 1.0 (0.4) and 0.9 (0.5) mm for axial and tilted implants, respectively, with no statistically significant differences between them (P > 0.05). The preliminary results suggest that this approach could allow the rehabilitation of posterior maxilla with immediate function in case of reduced bone volume, representing an alternative technique to bone grafting, short implants, and zygomatic or pterygoid implants.
From the *Department of Dentistry, Vita Salute University, San Raffaele Hospital, Milano, Italy; †Department of Medical, Oral and Biotechnological Sciences, University “G. d’Annunzio,” Chieti, Italy; and ‡Clinica di Chirurgia Maxillo-Facciale e Odontostomatologia, Università degli Studi di Verona. Received December 8, 2013. Accepted for publication March 4, 2014. Address correspondence and reprint requests to Enrico L. Agliardi, MD, DDS, Department of Dentistry, Vita Salute University, San Raffaele Hospital, Via Olgettina 48, 20123 Milano, Italy; E-mail: [email protected] The authors declare that no benefit of any kind will be received either directly or indirectly by the authors. The authors report no conflicts of interest. Davide Romeo is in private practice in Milano, Italy. Copyright © 2014 by Mutaz B. Habal, MD ISSN: 1049-2275 DOI: 10.1097/SCS.0000000000000959
Key Words: Partial fixed implant-supported restoration, immediate function, maxillary sinus, posterior maxilla, tilted implant (J Craniofac Surg 2014;25: 851–855)
I
mplant fixed rehabilitation of the posterior maxilla could represent a challenge for surgeons resulting in the lowest implant survival rates according to long-term reports.1,2 Frequently in long-term edentulism, severely resorbed ridges associated with pneumatization of the maxillary sinus might reduce the bone volume,3 and to face these limitations, a range of treatment options are available, such as the use of short implants4–7; crest augmentation8; sinus membrane elevation9,10; or fixtures placed in pterygoid region,11 tuber,12 or zygoma.13,14 All these procedures may have surgical and prosthetic risks and complications, reducing patients’ acceptance, and sometimes require a considerable surgical experience. Therefore, in some cases, the low bone density of posterior maxilla may negatively influence implants’ primary stability,15 thus compromising immediate loading procedures and consequently increasing total treatment time. Whenever possible, the use of correctly designed distal cantilever might represent an option to grafting without reducing implant and prosthetic success rates.16,17 Recently, the use of tilted implants connected to axial fixtures supporting partial or total fixed rehabilitations is well documented in literature,18–20 with high surgical and prosthetic success rates as well as remarkable biologic and biomechanical advantages.21–23 The following study aims to evaluate the treatment outcome of a new technique for fixed partial rehabilitation with immediate loading of the posterior maxilla with the use of 1 axial anterior implant and 1 posterior fixture with intrasinus mesial insertion. This report presents preliminary results up to 1 year of function on the implant survival and bone level change around axial and tilted implants.
MATERIALS AND METHODS This study was written following the Strengthening the Reporting of Observational studies in Epidemiology guidelines24 and was conducted according to the Declaration of Helsinki of 1975 for biomedical research involving human subjects, as revised in 2008. Initial examinations and inclusion of suitable patients started in 2009, and all subjects were treated by 1 maxillofacial surgeon with experience in implant-supported rehabilitations with immediate function and insertion of tilted implants. Patients were informed of the nature of the study, benefits, risks, and possible alternative treatments and signed an informed consent.
Inclusion and Exclusion Criteria Patients were included if they were older than 18 years and physically and psychologically able to undergo implant surgery and restorative procedures (American Academy of Anesthesiologist class 1 or 2).25 Further inclusion criteria were absence of maxillary premolars and at least first molar or presence of those teeth with unfavorable
The Journal of Craniofacial Surgery • Volume 25, Number 3, May 2014
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long-term prognosis, minimum crest width of 4 mm; adequate bone volume in the retrocanine area for implant placement at least 10-mm long, lack of available bone for short implant insertion under the sinus floor (20%), bruxism, or clenching. Preliminary screening and treatment planning were performed using panoramic radiograph (Fig. 1) and intraoral x-rays, with the help of a computerized tomographic scan if necessary. For this specific therapeutic option, no randomization was possible between the test (ie, tilted implants) and the control group (ie, axial implants). The DICOM files were acquired with a dedicated software (NobelClinician, Nobel Biocare) to get a tridimensional view of the surgical area and plan implants’ position and dimension. No surgical guides were made.
Surgical and Prosthetic Procedures Antibiotic prophylaxis was prescribed 1 hour before surgery, with 2 g of amoxicillin and clavulanic acid (Augmentin, Roche, Milan, Italy). Starting 3 days before surgery, chlorhexidine digluconate of 0.2% mouthwash (Curasept, Curaden Healthcare S.R.L., Milan, Italy) was also prescribed. A sedative premedication was administered to all patients with diazepam of 5 mg intravenously (Valium, Roche), and local anesthesia with articaine chlorhydrate/ adrenaline of 1:100,000 (Alfacaina N; Weimer Pharma, Rastatt, Germany) was used. A midcrestal incision was made starting from the pterygomaxillary region with a vertical releasing incision mesial to omolateral canine. A full-thickness mucoperiosteal buccal flap was raised exposing the facial bony wall. Using some references from panoramic radiograph and with a direct visualization of the vestibular bone, a bony window osteotomy with external bevel was performed through a piezoelectric device after the anterior sinus wall inclination (Fig. 2). The window was removed and stored in sterile saline solution, and the maxillary sinus membrane was gently reflected only in the anterior portion with manual instruments, without causing perforations (Fig. 3). With a 2-mm twist drill and starting from the area of the first molar, implant site
FIGURE 1. Preoperative panoramic radiograph reporting a fixed partial restoration supported by a first bicuspid and first molar with evident bone defects.
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FIGURE 2. A piezoelectric bony window osteotomy with external bevel was performed after the anterior sinus wall inclination.
preparation with a 30-degree mesial inclination was conducted, passing through the sinus cavity and ending in the apical portion of bone anterior to the sinus wall. The surgical site was underprepared with a 2.4- to 2.8-mm drill for the whole length and a 3.2-mm drill only for the most coronal part. A NobelSpeedy Groovy implant (Nobel Biocare AB, Göteborg, Sweden) with TiUnite was placed, finding stabilization in the crestal bone and in the portion of the cortical bone of the anterior sinus wall. One additional fixture was placed axially in position of the first premolar, engaging the palatal wall (Fig. 4). Both fixtures had a 4-mm diameter. Autogenous bone taken from tuberosity and from the mandibular ramus buccal shelf was used for the anterior gap of the socket and to fill the sinus cavity, surrounding completely the implant surface. The schneiderian membrane was adapted over the graft, and the bony window was repositioned using bony wax (Fig. 5). Cover screws were placed, and flap was closed with a 4-0 resorbable suture (Monocryl; Johnson & Johnson, St-Stevens-Woluwe, Belgium). A panoramic radiograph was performed soon after surgery to verify implant position (Fig. 6). A 30-degree multiunit abutment (Nobel Biocare AB, Göteborg, Sweden) was connected over the posterior implant, whereas standard abutment was screwed over the axial fixture and impression using sterile silicone material, and individual open tray was taken. After impression, healing caps were placed over the abutments to support the peri-implant mucosa during fabrication of the immediate prosthesis.Three hours after the surgery, a 3-unit acrylic resin provisional bridge was delivered, and the prosthetic screws were tightened at 10 Ncm using a torque controller. Occlusion was adjusted with a 40-μm articulating paper (Bausch Articulating Paper;
FIGURE 3. The anterior part of the sinus membrane was gently reflected with manual instruments.
© 2014 Mutaz B. Habal, MD
Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
The Journal of Craniofacial Surgery • Volume 25, Number 3, May 2014
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FIGURE 6. Panoramic radiograph taken immediately after implant placement.
FIGURE 4. The anterior implant was placed in the socket of the first premolar, whereas the posterior fixture found anchorage in the residual crestal bone and in the anterior sinus wall. Half of its surface was inside the sinus cavity, and it was covered by autogenous bone.
Nashua, NH), keeping slight contacts in maximum intercuspation and avoiding any lateral excursions. Prosthetic screws’ holes were filled with provisional resin cement (Fermit-N; Ivoclar Vivadent AG, Schaan, Liechtenstein), and patients were given instructions on home care, postsurgical pain, medication, and diet. After 6 months of function, final prostheses with a titanium CAD-CAM framework (Procera Implant Bridge; Nobel Biocare AB) and acrylic teeth were delivered, with full occlusal contacts and the absence of cantilevers (Figs. 7 and 8).
Outcome Measures The outcome measures evaluated for the current study were the following: 1. Prosthesis success: when the prosthesis was in function, without mobility and pain.26 Prosthesis stability was tested at each followup visit by means of 2 opposing instruments’ pressure. 2. Implant survival: when the implant was in function and stable with no evidence of peri-implant radiolucency and no suppuration or pain at the implant site or ongoing pathologic processes.27 3. Biological and prosthetic complications, such as peri-implantitis, fistulas, or abscess or any mechanical or prosthetic complications such as fracture of the implant and any prosthetic component.28,29
FIGURE 5. The bony window was repositioned before closing the flap.
4. Plaque and bleeding indexes at implant level.30 Each implant was examined on 4 aspects (mesial, distal, vestibular, and palatal). The percentage of sites in which plaque could be found, regardless of its amount, was recorded. Any site in which plaque could be visualized accounted for 12.5% (1/8) of the total score (100%). The same was done for bleeding index, considering positive any site that showed bleeding on probing. 5. Marginal bone level change: periapical radiographs were performed using a long-cone paralleling technique and an individual x-ray holder at baseline (delivering of provisional restoration), at 6 and 12 months and then yearly until the end of the follow-up period. Each radiograph was scanned at 600 dpi with a scanner (Epson Perfection Pro; Epson), and the marginal bone level was assessed with an image analysis software (UTHSCSA Image Tool version 3.00 for Windows; University of Texas Health Science Center in San Antonio, TX) by 1 experienced blind evaluator. The software was calibrated for every image using implant size as a known distance, and the calibration was checked by means of 2 measurements of fixture’s diameter at different levels. Implant neck was used as the reference for each measurement, and the linear distance between the neck and the most coronal bone-toimplant contact was measured. Mesial and distal values were averaged to have a single value for each implant.
FIGURE 7. Occlusal view of the final 3-unit bridge. Prosthetic screw holes were closed with composite.
© 2014 Mutaz B. Habal, MD
Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
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RESULTS Between 2009 and 2011, a total of 10 patients (6 women and 4 men) were consecutively treated, and each of them received a 3-unit fixed implant-supported rehabilitation with axial and tilted implants having intrasinus insertion. The mean age at surgery was 60.4 years (range, 55–70 y). Four patients were smokers (40%), showing a mean daily consumption of 5 cigarettes. A total of 20 implants (4 mm in diameter and length ranging between 11.5 and 25 mm) had a mean follow-up of 50 months (range, 42–57 mo). Four axial fixtures were placed in the postextraction socket. All implants reached at least 30 N of final torque. No implants were lost, and no biologic or mechanical complications were reported during surgical and restorative phases. Plaque index and bleeding index at 12 months of follow-up were 25% and 12.5%, respectively. After 1 year, bone loss had a mean (SD) of 1.0 (0.4) and 0.9 (0.5) mm for axial and tilted fixtures, respectively (P > 0.05), reporting 100% of implant and prosthetic success rates.
DISCUSSION The aim of this study was to evaluate the treatment outcome of a new technique for fixed partial rehabilitation with immediate loading of the posterior maxilla. This treatment option may represent an alternative technique in case of reduced bone height associated with mesial pneumatization of the sinus cavity up to the retrocanine area. Following this technique, a 3-unit bridge can be delivered 3 hours after the surgery, supported by 1 axial anterior implant and 1 posterior fixture with intrasinus mesial insertion, with limited or no posterior cantilever. Aparicio et al31 used a combination of axial and tilted implants to support partial fixed bridges as an alternative to sinus augmentation and evidenced a success rate for tilted fixtures similar to the axial ones. Balleri and colleagues32 and Calandriello et al33 reported encouraging results with a 3-unit fixed bridge supported by 1 axial implant and 1 tilted implant associated with a delayed and immediate loading protocol, respectively. Strain gauge measurements performed by Krekmanov et al22 showed no significant differences in bending moments and forces between axial and tilted implants, whereas finite element analysis models by Zampelis et al23 and Bellini et al34,35 evidenced that distal tilting of implants rigidly connected in a fixed restoration did not increase the stress in the marginal bone compared with axial fixtures. Our preliminary results show similar survival rates up to 1 year of follow-up between the axial and tilted implant groups, supporting the effectiveness of tilted implant as a valid therapeutic solution in selected clinical cases. Moreover, no statistically significant differences
in bone level change could be detected around implant in both groups, confirming that marginal bone loss is not affected by the tilting of the implants. Implant tilting is reported by numerous publications during previous years.18 Described advantages are composed of the placement of longer fixtures with consequently high level of primary stability and the reduction of posterior cantilever, thus reducing possible biologic and biomechanical complications related to unsupported prosthetic extensions.36–38 The innovative approach of the surgical procedures described in this study is related to the position of the posterior implant, which is different from previously mentioned clinical studies as it is not completely surrounded by residual bone. Intrasinus insertion results in placing the most coronal and apical portions of the fixture in the native bone, providing stabilization of these parts and sustaining the highest level of mechanical stress, whereas the implant body would be placed inside the sinus cavity and covered by bone graft. Thanks to the 30-degree inclination, it is possible to engage multiple layers of the cortical bone (alveolar crestal bone, floor of sinus cavity, anterior sinus wall) achieving high level of primary stability36–38 and getting a postoperative bone-to-implant contact similar to the one reached by shorter fixtures placed axially in the native bone. In this study, every patient was informed about alternative treatment modalities and, in particular, about the sinus floor augmentation with lateral approach, delayed 6-month implant placement (three fixtures), and fixed prosthesis 6 months after fixtures insertion39 or about the placement of a combination of 2 or 3 short implants (length ranging between 5 and 8.5 or 9 mm with osteotome technique) supporting a delayed 3-unit bridge with possible distal cantilever.40 According to the authors’ experience, both aforementioned alternative solutions were unable to satisfy patient’s desire of a restoration with immediate function because of the insufficient residual bone for proper implant stabilization, and although using short implants may bring advantages in reduced morbidity and biologic costs, the long-term success rate of the final restoration could be questionable.40 Reviewing the literature, it can be concluded that a minimum insertion torque of 35 N · cm is highly recommended for immediate loading procedures.41 The authors suggest a minimum of 4-mm crestal bone height and 4 mm of apical bone anchorage to achieve sufficient stabilization of the trans-sinus implant. This means that length, position, and inclination should be carefully planned, and a great experience with immediate loading surgical protocol and site underpreparation is necessary before starting with the described technique. Furthermore, a slightly tapered implant design or a fixture with a conical tip is preferred to increase primary stability. Within the limitations of this study, as the reduced number of patients and the limited follow-up, this technique could be considered as an effective alternative solution for the immediate rehabilitation of posterior maxilla with a reduced treatment time compared with sinus lift augmentation before implant placement or the use of short fixtures. These preliminary results are very encouraging, although long-term evaluation with a larger amount of patients and a multicenter study design are needed to confirm the validity of this surgical approach.
REFERENCES
FIGURE 8. Three-year periapical x-ray evidencing bone formation distal to the posterior implant.
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1. Becker W, Becker B, Alsuwyed A, et al. Long term evaluation of 282 implants in maxillary and mandibular molar position: a prospective study. J Periodontol 1999;70:896–901 2. Buser D, Mericske-Stern R, Bernanrd JP, et al. Long-term evaluation of non-submerged ITI implants. Part I: 8-years life table analysis of a prospective multi-center study with 2359 implants. Clin Oral Implants Res 1997;8:161–172
© 2014 Mutaz B. Habal, MD
Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
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3. Friberg B, et al. The posterior maxilla: clinical considerations and current concepts using Brånemark system implants. Periodontol 2000 2008;47:67–78 4. Felice P, Soardi E, Pellegrino G, et al. Treatment of the posterior atrophic edentulous maxilla: short implants versus bone augmentation for placing longer implants. Five-month post-loading results of a pilot randomised controlled trial. Eur J Oral Implantol 2011;4:191–202 5. Goené R, Bianchesi C, Huerzeler M, et al. Performance of short implants in partial restorations: 3-year follow-up of osseotite implants. Implant Dent 2005;14:274–280 6. Malò P, Nobre M, Lopes A, et al. Short implants in posterior jaw. A prospective 1-year study. Eur J Oral Implantol 2011;4:47–53 7. Malò P, De Araújo Nobre M, Rangert B, et al. Short implants placed one-stage in maxillae and mandibles: a retrospective clinical study with 1 to 9 years of follow-up. Clin Implant Dent Relat Res 2007;9:15–21 8. McAllister BS, Haghighat K, et al. Bone augmentation techniques. J Periodontol 2007;78:377–396 9. Graziani F, Donos N, Needleman I, et al. Comparison of implant serviva following sinus floor augmentation procedures with implants placed in pristine posterior maxillary bone: a systematic review. Clin Oral Implants Res 2004;15:677–682 10. Stern A, Green J, et al. Sinus lift procedures: an overview of current techniques. Dent Clin North Am 2012;56:219–233 11. Balshi TJ, Wolfinger GJ, Balshi SF, et al. Analysis of 356 pterygo-maxillary implants in edentulous arches for fixed prosthesis anchorage. Int J Oral Maxillofac Implants 1999;14:398–406 12. Bahat O, et al. Osseointegrated implants in the maxillary tuberosity: report on 45 consecutive patients. Int J Oral Maxillofac Implants 1992;7:459–467 13. Brånemark PI, Gröndahl K, Ohrnell LO, et al. Zygoma fixture in the management of advanced atrophy of the maxilla: technique and long-term results. Scand J Plast Reconstr Surg Hand Surg 2004;38:70–85 14. Malò P, De Araújo Nobre M, Lopes I, et al. A new approach to rehabilitate the severely atrophic maxilla using extramaxillary anchored implants in immediate function: a pilot study. J Prosthet Dent 2008;100:354–366 15. Sogo M, Ikebe K, Yang TC, et al. Assessment of bone density in the posterior maxilla based on Hounsfield units to enhance the initial stability of implants. Clin Implant Dent Relat Res 2012 16. Wennström J, Zurdo J, Karlsson S, et al. Bone level change at implant-supported fixed partial dentures with and without cantilever extension after 5 years of function. J Clin Periodontol 2004;31:1077–1083 17. Rangert B, Sullivan RM, Jemt T, et al. Load factor control for implants in the posterior partially edentulous segments. Int J Oral Maxillofac Implants 1997;12:360–370 18. Del Fabbro M, Bellini CM, Romeo D, et al. Tilted implants for the rehabilitation of edentulous jaws. A systematic review. Clin Implant Dent Relat Res 2010 19. Agliardi E, Panigatti S, Clericò M, et al. Immediate rehabilitation of the edentulous jaws with full prostheses supported by four implants: interim results of a single cohort prospective study. Clin Oral Implants Res 2010;21:459–465 20. Malò P, de Araújo Nobre M, Lopes A, et al. A Longitudinal study of the survival of all-on-four implants in the mandible with up to 10 years of follow-up. J Am Dent Assoc 2011;142:310–320 21. Aparicio C, Perales P, Rangert B, et al. Tilted implants as an alternative to maxillary sinus grafting: a clinical, radiologic, and periotest study. Clin Implant Dent Relat Res 2001;3:39–49
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22. Krekmanov L, Kahn M, Rangert B, et al. Tilting of posterior mandibular and maxillary implants for improved prosthesis support. Int J Oral Maxillofac Implants 2000;15:405–414 23. Zampelis A, Rangert B, Heijl L, et al. Tilting of splinted implants for improved prosthodontic support: a two-dimensional finite element analysis. J Prosthet Dent 2007;97(suppl 6):S35–S43 24. von Elm E, Altman DG, Egger M, et al. STROBE initiative. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement: guidelines for reporting observational studies. J Clin Epidemiol 2008;61:344–349 25. Keats AS. The ASA classification of physical status—a recapitulation. Anesthesiology 1978;4:233–236 26. California Dental Association. Quality evaluation for dental care: guidelines for the assessment of clinical quality and professional performance. Los Angeles: California Dental Association 1977 27. Sacca S, Coulthard P, et al. Implant failure: etiology and complications. Med Oral Patol Oral Cir Bucal 2011;16:42–44 28. Esposito M, Hirsch JM, Lekholm U, et al. Biological factors contributing to failures of osseointegrated oral implants. (II). Etiopathogenesis. Eur J Oral Sci1 998;106:721–764 29. Zurdo J, Romão C, Wennström JL, et al. Survival and complication rates of implant-supported fixed partial dentures with cantilevers: a systematic review. Clin Oral Implants Res 2009;20:59–66 30. Mombelli A, Lang NP, et al. Clinical parameters for the evaluation of dental implants. Periodontol 2000 1994;4:81–86 31. Aparicio C, Arévalo JX, Ouazzani W, et al. Retrospective clinical and radiographic evaluation of tilted implants used in the treatment of the severely resorbed edentulous maxilla. Appl Osseointeg Res 2002;3:17–21 32. Balleri P, Ferrari M, Veltri M, et al. One-year outcome of implants strategically placed in the retrocanine bone triangle. Clin Implant Dent Relat Res 2010;12:324–330 33. Calandriello R, Tomatis Met al. Simplified treatment of the atrophic posterior maxilla via immediate/early function and tilted implants: a prospective 1-year clinical study. Clin Implant Dent Rel Res 2005;7(suppl 1):S1–S12 34. Bellini CM, Romeo D, Galbusera F, et al. Rehabilitation of completely edentulous mandibles. All-on-Four versus Toronto—Brånemark: a biomechanical study. Int J Oral Maxillofac Implants 2009;24:511–517 35. Bellini CM, Romeo D, Galbusera F, et al. Rehabilitation of completely edentulous maxillae. Tilted versus non-tilted implant configuration: a biomechanical study. Int J Prosthodont 2009;22:155–157 36. Maló P, Rangert B, Nobre M, et al. All-on-4 immediate-function concept with Brånemark System implants for completely edentulous maxillae: a 1-year retrospective clinical study. Clin Implant Dent Relat Res 2005;7(suppl 1):S88–S94 37. Agliardi E, Francetti L, Romeo D, et al. Immediate rehabilitation of the edentulous maxilla: preliminary results of a single cohort prospective study. Int J Oral Maxillofac Implants 2009;24:887–895 38. Agliardi E, Clericò M, Ciancio P, et al. Immediate loading of full-arch fixed prostheses supported by axial and tilted implants for the treatment of edentulous atrophic mandibles. Quintessence Int 2010;41:285–293 39. Del Fabbro M, Rosano G, Taschieri S, et al. Implant survival after maxillary sinus augmentation. Eur J Oral Sci 2008;116:497–506 40. Annibali S, Cristalli MP, Dell’Aquila D, et al. Short dental implants: a systematic review. J Dent Res 2012;91:25–32 41. Javed F, Romanos GE. The role of primary stability for successful immediate loading of dental implants. A literature review. J Dent 2010;38:612–620
© 2014 Mutaz B. Habal, MD
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Immediate Function of Partial Fixed Rehabilitation With Axial and Tilted Implants Having Intrasinus Insertion Enrico Luigi Agliardi, MD, DDS,* Stefano Tetè, MD, DDS,† Davide Romeo, DDS, PhD Luciano Malchiodi, MD, DDS,‡ and Enrico Gherlone, MD, DMD* Abstract: Implant-supported rehabilitation of the posterior maxilla could be challenging because hyperpneumatization of the maxillary sinus might reduce the bone height. In this study, the authors report preliminary results of a new treatment modality for the partial fixed rehabilitation of posterior maxilla with immediate function by using 1 anterior axial implant and 1 posterior tilted implant with intrasinus mesial insertion. From 2009 to 2011, 10 patients (6 women and 4 men) with missing upper premolars and molars were recruited and treated according to this protocol. Each patient received a partial fixed bridge supported by 1 axial anterior implant and 1 posterior implant placed with a 30-degree mesial inclination and intrasinus insertion. Autologous bone was positioned to fill the maxillary sinus cavity and to cover the exposed implant surface after elevation of the anterior sinus membrane. A prosthesis with immediate function was positioned within 3 hours, whereas a CAD/CAM final restoration was delivered 6 months later. Follow-ups at 6 and 12 months, and then annually, were scheduled. At each follow-up, plaque level and bleeding scores were assessed, and radiographic evaluation of marginal bone level change was performed at 1 year. The patients were followed up for a mean of 50 months (range, 42–57 mo). No implants were lost, and all prostheses were stable and functional, reporting 100% of implant and prosthetic success rates. After 1 year, bone loss had a mean (SD) of 1.0 (0.4) and 0.9 (0.5) mm for axial and tilted implants, respectively, with no statistically significant differences between them (P > 0.05). The preliminary results suggest that this approach could allow the rehabilitation of posterior maxilla with immediate function in case of reduced bone volume, representing an alternative technique to bone grafting, short implants, and zygomatic or pterygoid implants.
From the *Department of Dentistry, Vita Salute University, San Raffaele Hospital, Milano, Italy; †Department of Medical, Oral and Biotechnological Sciences, University “G. d’Annunzio,” Chieti, Italy; and ‡Clinica di Chirurgia Maxillo-Facciale e Odontostomatologia, Università degli Studi di Verona. Received December 8, 2013. Accepted for publication March 4, 2014. Address correspondence and reprint requests to Enrico L. Agliardi, MD, DDS, Department of Dentistry, Vita Salute University, San Raffaele Hospital, Via Olgettina 48, 20123 Milano, Italy; E-mail: [email protected] The authors declare that no benefit of any kind will be received either directly or indirectly by the authors. The authors report no conflicts of interest. Davide Romeo is in private practice in Milano, Italy. Copyright © 2014 by Mutaz B. Habal, MD ISSN: 1049-2275 DOI: 10.1097/SCS.0000000000000959
Key Words: Partial fixed implant-supported restoration, immediate function, maxillary sinus, posterior maxilla, tilted implant (J Craniofac Surg 2014;25: 851–855)
I
mplant fixed rehabilitation of the posterior maxilla could represent a challenge for surgeons resulting in the lowest implant survival rates according to long-term reports.1,2 Frequently in long-term edentulism, severely resorbed ridges associated with pneumatization of the maxillary sinus might reduce the bone volume,3 and to face these limitations, a range of treatment options are available, such as the use of short implants4–7; crest augmentation8; sinus membrane elevation9,10; or fixtures placed in pterygoid region,11 tuber,12 or zygoma.13,14 All these procedures may have surgical and prosthetic risks and complications, reducing patients’ acceptance, and sometimes require a considerable surgical experience. Therefore, in some cases, the low bone density of posterior maxilla may negatively influence implants’ primary stability,15 thus compromising immediate loading procedures and consequently increasing total treatment time. Whenever possible, the use of correctly designed distal cantilever might represent an option to grafting without reducing implant and prosthetic success rates.16,17 Recently, the use of tilted implants connected to axial fixtures supporting partial or total fixed rehabilitations is well documented in literature,18–20 with high surgical and prosthetic success rates as well as remarkable biologic and biomechanical advantages.21–23 The following study aims to evaluate the treatment outcome of a new technique for fixed partial rehabilitation with immediate loading of the posterior maxilla with the use of 1 axial anterior implant and 1 posterior fixture with intrasinus mesial insertion. This report presents preliminary results up to 1 year of function on the implant survival and bone level change around axial and tilted implants.
MATERIALS AND METHODS This study was written following the Strengthening the Reporting of Observational studies in Epidemiology guidelines24 and was conducted according to the Declaration of Helsinki of 1975 for biomedical research involving human subjects, as revised in 2008. Initial examinations and inclusion of suitable patients started in 2009, and all subjects were treated by 1 maxillofacial surgeon with experience in implant-supported rehabilitations with immediate function and insertion of tilted implants. Patients were informed of the nature of the study, benefits, risks, and possible alternative treatments and signed an informed consent.
Inclusion and Exclusion Criteria Patients were included if they were older than 18 years and physically and psychologically able to undergo implant surgery and restorative procedures (American Academy of Anesthesiologist class 1 or 2).25 Further inclusion criteria were absence of maxillary premolars and at least first molar or presence of those teeth with unfavorable
The Journal of Craniofacial Surgery • Volume 25, Number 3, May 2014
Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
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long-term prognosis, minimum crest width of 4 mm; adequate bone volume in the retrocanine area for implant placement at least 10-mm long, lack of available bone for short implant insertion under the sinus floor (20%), bruxism, or clenching. Preliminary screening and treatment planning were performed using panoramic radiograph (Fig. 1) and intraoral x-rays, with the help of a computerized tomographic scan if necessary. For this specific therapeutic option, no randomization was possible between the test (ie, tilted implants) and the control group (ie, axial implants). The DICOM files were acquired with a dedicated software (NobelClinician, Nobel Biocare) to get a tridimensional view of the surgical area and plan implants’ position and dimension. No surgical guides were made.
Surgical and Prosthetic Procedures Antibiotic prophylaxis was prescribed 1 hour before surgery, with 2 g of amoxicillin and clavulanic acid (Augmentin, Roche, Milan, Italy). Starting 3 days before surgery, chlorhexidine digluconate of 0.2% mouthwash (Curasept, Curaden Healthcare S.R.L., Milan, Italy) was also prescribed. A sedative premedication was administered to all patients with diazepam of 5 mg intravenously (Valium, Roche), and local anesthesia with articaine chlorhydrate/ adrenaline of 1:100,000 (Alfacaina N; Weimer Pharma, Rastatt, Germany) was used. A midcrestal incision was made starting from the pterygomaxillary region with a vertical releasing incision mesial to omolateral canine. A full-thickness mucoperiosteal buccal flap was raised exposing the facial bony wall. Using some references from panoramic radiograph and with a direct visualization of the vestibular bone, a bony window osteotomy with external bevel was performed through a piezoelectric device after the anterior sinus wall inclination (Fig. 2). The window was removed and stored in sterile saline solution, and the maxillary sinus membrane was gently reflected only in the anterior portion with manual instruments, without causing perforations (Fig. 3). With a 2-mm twist drill and starting from the area of the first molar, implant site
FIGURE 1. Preoperative panoramic radiograph reporting a fixed partial restoration supported by a first bicuspid and first molar with evident bone defects.
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FIGURE 2. A piezoelectric bony window osteotomy with external bevel was performed after the anterior sinus wall inclination.
preparation with a 30-degree mesial inclination was conducted, passing through the sinus cavity and ending in the apical portion of bone anterior to the sinus wall. The surgical site was underprepared with a 2.4- to 2.8-mm drill for the whole length and a 3.2-mm drill only for the most coronal part. A NobelSpeedy Groovy implant (Nobel Biocare AB, Göteborg, Sweden) with TiUnite was placed, finding stabilization in the crestal bone and in the portion of the cortical bone of the anterior sinus wall. One additional fixture was placed axially in position of the first premolar, engaging the palatal wall (Fig. 4). Both fixtures had a 4-mm diameter. Autogenous bone taken from tuberosity and from the mandibular ramus buccal shelf was used for the anterior gap of the socket and to fill the sinus cavity, surrounding completely the implant surface. The schneiderian membrane was adapted over the graft, and the bony window was repositioned using bony wax (Fig. 5). Cover screws were placed, and flap was closed with a 4-0 resorbable suture (Monocryl; Johnson & Johnson, St-Stevens-Woluwe, Belgium). A panoramic radiograph was performed soon after surgery to verify implant position (Fig. 6). A 30-degree multiunit abutment (Nobel Biocare AB, Göteborg, Sweden) was connected over the posterior implant, whereas standard abutment was screwed over the axial fixture and impression using sterile silicone material, and individual open tray was taken. After impression, healing caps were placed over the abutments to support the peri-implant mucosa during fabrication of the immediate prosthesis.Three hours after the surgery, a 3-unit acrylic resin provisional bridge was delivered, and the prosthetic screws were tightened at 10 Ncm using a torque controller. Occlusion was adjusted with a 40-μm articulating paper (Bausch Articulating Paper;
FIGURE 3. The anterior part of the sinus membrane was gently reflected with manual instruments.
© 2014 Mutaz B. Habal, MD
Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
The Journal of Craniofacial Surgery • Volume 25, Number 3, May 2014
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FIGURE 6. Panoramic radiograph taken immediately after implant placement.
FIGURE 4. The anterior implant was placed in the socket of the first premolar, whereas the posterior fixture found anchorage in the residual crestal bone and in the anterior sinus wall. Half of its surface was inside the sinus cavity, and it was covered by autogenous bone.
Nashua, NH), keeping slight contacts in maximum intercuspation and avoiding any lateral excursions. Prosthetic screws’ holes were filled with provisional resin cement (Fermit-N; Ivoclar Vivadent AG, Schaan, Liechtenstein), and patients were given instructions on home care, postsurgical pain, medication, and diet. After 6 months of function, final prostheses with a titanium CAD-CAM framework (Procera Implant Bridge; Nobel Biocare AB) and acrylic teeth were delivered, with full occlusal contacts and the absence of cantilevers (Figs. 7 and 8).
Outcome Measures The outcome measures evaluated for the current study were the following: 1. Prosthesis success: when the prosthesis was in function, without mobility and pain.26 Prosthesis stability was tested at each followup visit by means of 2 opposing instruments’ pressure. 2. Implant survival: when the implant was in function and stable with no evidence of peri-implant radiolucency and no suppuration or pain at the implant site or ongoing pathologic processes.27 3. Biological and prosthetic complications, such as peri-implantitis, fistulas, or abscess or any mechanical or prosthetic complications such as fracture of the implant and any prosthetic component.28,29
FIGURE 5. The bony window was repositioned before closing the flap.
4. Plaque and bleeding indexes at implant level.30 Each implant was examined on 4 aspects (mesial, distal, vestibular, and palatal). The percentage of sites in which plaque could be found, regardless of its amount, was recorded. Any site in which plaque could be visualized accounted for 12.5% (1/8) of the total score (100%). The same was done for bleeding index, considering positive any site that showed bleeding on probing. 5. Marginal bone level change: periapical radiographs were performed using a long-cone paralleling technique and an individual x-ray holder at baseline (delivering of provisional restoration), at 6 and 12 months and then yearly until the end of the follow-up period. Each radiograph was scanned at 600 dpi with a scanner (Epson Perfection Pro; Epson), and the marginal bone level was assessed with an image analysis software (UTHSCSA Image Tool version 3.00 for Windows; University of Texas Health Science Center in San Antonio, TX) by 1 experienced blind evaluator. The software was calibrated for every image using implant size as a known distance, and the calibration was checked by means of 2 measurements of fixture’s diameter at different levels. Implant neck was used as the reference for each measurement, and the linear distance between the neck and the most coronal bone-toimplant contact was measured. Mesial and distal values were averaged to have a single value for each implant.
FIGURE 7. Occlusal view of the final 3-unit bridge. Prosthetic screw holes were closed with composite.
© 2014 Mutaz B. Habal, MD
Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
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RESULTS Between 2009 and 2011, a total of 10 patients (6 women and 4 men) were consecutively treated, and each of them received a 3-unit fixed implant-supported rehabilitation with axial and tilted implants having intrasinus insertion. The mean age at surgery was 60.4 years (range, 55–70 y). Four patients were smokers (40%), showing a mean daily consumption of 5 cigarettes. A total of 20 implants (4 mm in diameter and length ranging between 11.5 and 25 mm) had a mean follow-up of 50 months (range, 42–57 mo). Four axial fixtures were placed in the postextraction socket. All implants reached at least 30 N of final torque. No implants were lost, and no biologic or mechanical complications were reported during surgical and restorative phases. Plaque index and bleeding index at 12 months of follow-up were 25% and 12.5%, respectively. After 1 year, bone loss had a mean (SD) of 1.0 (0.4) and 0.9 (0.5) mm for axial and tilted fixtures, respectively (P > 0.05), reporting 100% of implant and prosthetic success rates.
DISCUSSION The aim of this study was to evaluate the treatment outcome of a new technique for fixed partial rehabilitation with immediate loading of the posterior maxilla. This treatment option may represent an alternative technique in case of reduced bone height associated with mesial pneumatization of the sinus cavity up to the retrocanine area. Following this technique, a 3-unit bridge can be delivered 3 hours after the surgery, supported by 1 axial anterior implant and 1 posterior fixture with intrasinus mesial insertion, with limited or no posterior cantilever. Aparicio et al31 used a combination of axial and tilted implants to support partial fixed bridges as an alternative to sinus augmentation and evidenced a success rate for tilted fixtures similar to the axial ones. Balleri and colleagues32 and Calandriello et al33 reported encouraging results with a 3-unit fixed bridge supported by 1 axial implant and 1 tilted implant associated with a delayed and immediate loading protocol, respectively. Strain gauge measurements performed by Krekmanov et al22 showed no significant differences in bending moments and forces between axial and tilted implants, whereas finite element analysis models by Zampelis et al23 and Bellini et al34,35 evidenced that distal tilting of implants rigidly connected in a fixed restoration did not increase the stress in the marginal bone compared with axial fixtures. Our preliminary results show similar survival rates up to 1 year of follow-up between the axial and tilted implant groups, supporting the effectiveness of tilted implant as a valid therapeutic solution in selected clinical cases. Moreover, no statistically significant differences
in bone level change could be detected around implant in both groups, confirming that marginal bone loss is not affected by the tilting of the implants. Implant tilting is reported by numerous publications during previous years.18 Described advantages are composed of the placement of longer fixtures with consequently high level of primary stability and the reduction of posterior cantilever, thus reducing possible biologic and biomechanical complications related to unsupported prosthetic extensions.36–38 The innovative approach of the surgical procedures described in this study is related to the position of the posterior implant, which is different from previously mentioned clinical studies as it is not completely surrounded by residual bone. Intrasinus insertion results in placing the most coronal and apical portions of the fixture in the native bone, providing stabilization of these parts and sustaining the highest level of mechanical stress, whereas the implant body would be placed inside the sinus cavity and covered by bone graft. Thanks to the 30-degree inclination, it is possible to engage multiple layers of the cortical bone (alveolar crestal bone, floor of sinus cavity, anterior sinus wall) achieving high level of primary stability36–38 and getting a postoperative bone-to-implant contact similar to the one reached by shorter fixtures placed axially in the native bone. In this study, every patient was informed about alternative treatment modalities and, in particular, about the sinus floor augmentation with lateral approach, delayed 6-month implant placement (three fixtures), and fixed prosthesis 6 months after fixtures insertion39 or about the placement of a combination of 2 or 3 short implants (length ranging between 5 and 8.5 or 9 mm with osteotome technique) supporting a delayed 3-unit bridge with possible distal cantilever.40 According to the authors’ experience, both aforementioned alternative solutions were unable to satisfy patient’s desire of a restoration with immediate function because of the insufficient residual bone for proper implant stabilization, and although using short implants may bring advantages in reduced morbidity and biologic costs, the long-term success rate of the final restoration could be questionable.40 Reviewing the literature, it can be concluded that a minimum insertion torque of 35 N · cm is highly recommended for immediate loading procedures.41 The authors suggest a minimum of 4-mm crestal bone height and 4 mm of apical bone anchorage to achieve sufficient stabilization of the trans-sinus implant. This means that length, position, and inclination should be carefully planned, and a great experience with immediate loading surgical protocol and site underpreparation is necessary before starting with the described technique. Furthermore, a slightly tapered implant design or a fixture with a conical tip is preferred to increase primary stability. Within the limitations of this study, as the reduced number of patients and the limited follow-up, this technique could be considered as an effective alternative solution for the immediate rehabilitation of posterior maxilla with a reduced treatment time compared with sinus lift augmentation before implant placement or the use of short fixtures. These preliminary results are very encouraging, although long-term evaluation with a larger amount of patients and a multicenter study design are needed to confirm the validity of this surgical approach.
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FIGURE 8. Three-year periapical x-ray evidencing bone formation distal to the posterior implant.
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Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
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