Volume 39, Issue 6 , Pages 606-609, June 2010
Palatal piezosurgical window osteotomy for maxillary sinus augmentation
Article Outline
- Abstract
- Surgical technique
- Discussion
- Competing interests
- Funding
- Ethical approval
- Acknowledgements
- References
- Copyright
Abstract
This technical note describes a new surgical technique for a palatal approach to the maxillary sinus for a vertical augmentation prior to dental implant placement. In 12 fully or partially edentulous patients (seven women, five men), 16 palatal sinus elevations were performed. After elevation of palatal full-thickness flap a rectangular access window was cut with a piezosurgical device. The raised sinus cavity was augmented with a synthetic nano-structured hydroxyapatite-based graft material. No harm occurred to the greater palatine artery or the sinus membrane. The vestibular and periimplant gingiva were preserved and there was no disharmonious soft tissue distortion or massive scar formation. Swelling and bleeding were minimal. Primary stability was achieved for all but one implant. This technique may be an alternative to other sinus augmentation approaches in cases where enough transversal width of the posterior alveolar crest is available.
Maxillary sinus floor augmentation is an integral part of modern implantology. The most widely practised method is the classical lateral antrostomy approach with a trap-door design and its modifications5. The trap-door is rotated medially to push the schneiderian membrane cranially and create a chamber with a cortical ceiling. The major variations of the original lateral antrostomy technique can be classified as hinge osteotomy, elevated osteotomy, complete osteotomy and crestal osteotomy1. Implants can be inserted simultaneously with the graft (one-stage lateral antrostomy) or at a later time (two-stage lateral antrostomy).
A more conservative sinus augmentation approach using osteotomes was introduced in 1994 by Summers7. Today a variety of modifications can be found in the literature5, 9. Based on these two principal concepts for sinus augmentation, other different and modified techniques for the crestal and lateral approach to the maxillary sinus have been introduced3. The development and subsequent success of piezoelectric osteotomies has suggested new ideas for bone cutting and surgical procedures. This technical note introduces a new palatal approach to the maxillary sinus using piezosurgery for maxillary sinus elevation. Inclusion criteria were that patients had to be free of sinus pathology and have a reduced height alveolar crest at the prospective implant site. The residual height of the alveolar bone had to be less than 5
mm, which was assessed by preoperative radiographs. The minimum transversal width of the alveolar crest had to be 7mm, which was measured during basic evaluation using a caliper. Patients were in good systemic health with no contraindications for oral surgical interventions.
Surgical technique
From the patient pool of the Department of Maxillofacial and Facial Plastic Surgery, Frankfurt, 12 fully or partially edentulous patients (seven women, five men) designated for implant treatment in the posterior maxilla were selected from March 2007 to December 2007. The study group had an average age of 55 years (range: 22–70 years). All participants had to sign written informed consent prior to the sinus augmentation procedure. The surgical procedure was performed either under general anaesthesia (four patients with bilateral sinus elevation) or local anaesthesia (eight patients with unilateral sinus elevation) by one surgeon. Following a slightly palatally located crestal and bevelled incision with an oblique releasing incision in the premolar region a full-thickness flap was raised to access the palatal bone wall of the maxillary sinus. By locating the crestal incision slightly palatally, the periosteum and the attached gingiva in the delicate vestibular and later periimplant region were preserved, because they were not opened up. The mesial palatal releasing incision in the premolar region was easy to perform and no massive bleeding of lesser palatine arteries occurred. An intraoperative coagulation procedure was not necessary.
Once the flap had been raised to allow the desired osteotomy approach it was carefully held off with fixation sutures. Owing to the lack of a distal releasing incision, the blood supply of the flap through the greater palatine artery retained its undisturbed blood circulation. No accessory cheek retractors were used. The antrostomy was performed using the piezosurgery device (Mectron, Carasco, Italy). Selected parameters for the osteotomy with the OT2 scalpel were ‘bone quality one’ with additionally water cooling (pump output of 50%). A complete window osteotomy for later palatal sinus elevation (WOLPE) was carried out with a rectangular pattern (Fig. 1). The time need for piezoelectric bone cutting was comparable to the lateral approach. Palatal handling of the handpiece was as straightforward as using an instrument on the buccal part.
Fig. 1.
Mucoperiosteal flap elevation and window osteotomy for later palatal sinus elevation.
After osteotomy, the palatal bony lid was completely removed and the sinus membrane was meticulously dissected and lifted by elevators in a way similar to the lateral approach technique (Fig. 2). In all cases, the membrane was prepared until the instruments had direct contact with the buccal plate. The empty space was grafted with a new entirely synthetic and nano-structured hydroxyapatite-based biomaterial embedded in a highly porous matrix of silica gel (NanoBone®). The biomaterial was mixed with blood gained from the surgical site and was densely packed into the cavity. No additional autogenous bone blocks or chips were used. After filling the whole prepared space, excessive particles of the graft material were removed and the palatal bony lid was readapted at the original place (Fig. 3). The underlying bony lid could be securely stabilized in its position because of the steady fitting and the absence of muscular traction forces or functional movements.
Fig. 2.
Palatal bony lid after removal. Note the thickness of the mesial (right) part of the bone lid, because of the anatomical site.
Fig. 3.
Readapting the palatal bony lid on the original place. No membrane is placed over the defect.
Additional covering of the surgical site with a membrane was not performed. The fixation suture of the palatal flap was removed and the flap was repositioned without any periosteal horizontal releasing incisions. Primary wound closure was accomplished with resorbable tension-free single sutures. Postoperative medication included analgesics, and 0.1% chlorhexidine-digluconate mouth rinse for 10 days. Follow-up examinations were performed routinely at 2 days, 14 days and 3 months after surgery.
The preliminary results of implant healing after 3 months (six patients) and 6 months (six patients) and comparison with a conventional technique were published in an e-first publication by the same group.
Discussion
This technical note describes a new piezosurgical window osteotomy for later palatal sinus elevation. In comparison with the traditional lateral surgical approach to the maxillary sinus, the authors see the main advantages of this new technique as favourable soft tissue management, and valuable aggregation and condensation of the applied augmentation material at the inner palatal part of the alveolar crest.
Another aspect in favour of the WOLPE technique is the sometimes paper-thin character of the buccal and inferior walls of the maxillary sinus. Sufficient blood supply is essential for the survival and integration of the graft material following sinus floor elevation. The lateral maxilla is supplied by branches of the posterior superior alveolar and infraorbital arteries that form anastomoses within the bony lateral wall of the maxillary sinus. This intraosseous anastomosis also supplies the schneiderian membrane6. As the resorption of the cancellous bone inside the alveolar crest progresses, the lateral and inferior walls of the sinus are reduced to paper-thin lamellae of cortical bone, which are no longer supplied by intraosseous vessels, but solely by the vessels in the local periosteum. The preservation of the periosteal blood supply at the buccal side of the lateral maxilla is therefore of special importance for protecting the bone from additional resorption.
The mesial angled incision in the WOLPE technique offers the elevated flap a good blood and nutrient supply not only through a lateral diffusion, as in the case of the lateral technique, but also through the branches of the greater palatine artery4. The absence of muscular traction forces or functional movements during wound healing also reduces the risk of dehiscence with consequent infection8. The tight interconnection of the palatal mucosa with the underlying periosteum allows an exact readapting of the flap on the palatal bone wall and therefore does not lead to distortion of soft tissue structures10. A subsequent plastic periodontal surgical intervention such as a vestibuloplasty or any soft tissue grafting for functional or aesthetic reasons is not necessary. The inherent stability of the palatal mucosa also decreases the extension of pronounced hard and soft palate swelling. This, together with minimal swelling of the vestibule and cheeks due to the palatal surgical site, and the lack of retraction forces enables the patients to wear their overdentures almost immediately after the surgical procedure.
The WOLPE technique also has some disadvantages. First, the inherent design of the flap does not allow a simultaneous lateral alveolar ridge augmentation in case of severe vestibular atrophy or defect, so the technique can be recommended if the residual transversal width of the crest allows a functional and stable implant placement with a certain diameter. Second, concerning the shape of the alveolar crest, a reduced height or flattened form make the procedure more difficult because the osteotomy has to be performed through very thick and compact palatal bone2. Third, a further surgical disadvantage may be the potential risk to structures of the greater palatine artery during the initial incision causing intraoperative bleeding. Although as the mesial releasing incision is mainly in the premolar region, this risk is negligible. Another postoperative complication may be temporary or permanent neurosensory disturbance of the hard palate.
In conclusion, as the WOLPE technique allows promising hard and soft tissue management it is an attractive alternative in cases where enough transversal width of the posterior alveolar crest is available.
Competing interests
None declared.
Funding
Parts of this work were funded by scientific grants from the National Center of Competence in Research (NCCR) CO-ME of the Swiss National Science Foundation, Berne, Switzerland, and the Camlog Foundation, Basle, Switzerland.
Ethical approval
Not required.
Acknowledgements
Preliminary data of a comparative study using this technique have been e-published elsewhere by the same group. The graft material, NanoBone, was kindly provided for free by Artoss GmbH, Rostock, Germany. The authors gratefully acknowledge Ms. Lucy Irwin, EPO, Munich, Germany for language checking the manuscript.
References
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- . Arterial supply of the oral mucosa. Acta Anat (Basel). 1991;142:374–378
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- . Blood supply to the maxillary sinus relevant to sinus floor elevation procedures. Clin Oral Implants Res. 1999;10:34–44
- . A new concept in maxillary implant surgery: the osteotome technique. Compend Contin Educ Dent. 1994;15:152–162
- . Musculature of the soft palate: clinico-anatomic correlations and therapeutic implications in the treatment of cleft palates. Cleft Palate Craniofac J. 1997;34:189–194
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PII: S0901-5027(10)00093-7
doi:10.1016/j.ijom.2010.03.001
© 2010 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.
Volume 39, Issue 6 , Pages 606-609, June 2010
