What Are the Clinical Challenges Faced in Posterior Maxillary Prosthetic Rehabilitation?
Dental implants are considered the gold standard for edentulous patients. Dental implants are reliable in patients who are ideal or suitable for them. They are deemed the best by the dental surgeon to attain maximal chewing efficiency compared to dentures and bridges. The complication or clinical challenge that is predictable after tooth loss or edentulism is bone loss both in horizontal and vertical directions.
The posterior region of the upper jaw (around premolars and molar) mainly creates great difficulty for an implant dentist to achieve superior functionality and prosthetic efficiency even after implant placement. This is because the stress-bearing load (also called functional load) upon the alveolar ridge in the posterior upper jaw region undergoes a remodeling process that is relatively continuous post tooth loss. That is why compared to other areas, the prosthetic rehabilitation of the posterior maxillary region is even more challenging, given the amount of bone that gets resorbed in the region is not replaced by a prosthesis or a dental implant post tooth loss. Therefore, continuous remodeling and loss of bone height remain the primary challenge. The minor challenge that may further complicate the surgical implantation in this area is the presence of the Schneiderian membrane that contains a periosteum with very high osteoclast activity. When higher in number, osteoclasts or bone-resorbing cells (in contrast to or unlike the osteoblasts or bone-forming cells) tend to resorb the bone easily. Also, the maxillary sinus thus undergoes pneumatization due to the osteoclastic or bone-resorbing activity within the Schneiderian membrane (the maxillary sinus membrane).
All these factors hence lead to a low possibility of clinical success rates in this posterior maxillary region owing to the difficulties due to the reduced bone support available for dental implants to osseointegrate or undergo a fusion into the jaw bone (bone-implant contact or osseointegration).
What Is the Purpose of Sinus Lift or Elevation Surgery?
The anatomic or physiologic deficiency in this region is addressed by the implant dentist in the form of the sinus lift procedure wherein the maxillary sinus floor is elevated. The deficiency is restored by the internal augmentation of the maxillary sinus wherein mainly, and firstly the Schneiderian membrane is raised or elevated so that the implants in this region of the upper jaw can be placed successfully. Bone height after sinus elevation is also obtained by augmentation procedures and bone materials used in the form of autografts (a graft of tissue from an individual’s body, allografts (tissue graft from a donor of the same species), xenografts (tissue graft from a donor of different species), or alloplastic materials to redeem the lost biologic height of the bone (that occurs after the horizontal or vertical dimension reduction post tooth loss). The most conventional sinus augmentation or sinus lift techniques include the lateral approach to the maxillary sinus and the crestal (a bone forming a ridge or a crest around the crown of the teeth) approach.
What Is the Hydraulic Pressure Technique for Sinus Elevation?
As opposed to the disadvantages encountered by the crestal or lateral sinus floor approach, such as the increased risk of sinus membrane perforation or post-operative pain, these risks can be significantly reduced or minimized in the hydraulic pressure techniques. Also, the chairside time between the implant dentist and the patient is considerably reduced as it is a fast-paced procedure, and this is by utilizing a unique water lift system.
This technique was initially proposed by Chen and Cha in 2005 and was again improvised upon in the year 2012 by introducing the water lift system or aqua system. These systems utilize hydraulic pressure to separate the sinus membrane from the lateral wall of the sinus floor. By the principle of equal pressure exertion upon both the membrane and the lateral wall of the sinus, the uniform elevation of the sinus membrane is made possible through this unique technique that results in the preservation of the Schneiderian membrane integrity.
How Is Hydraulic Pressure Technique for Sinus Elevation Performed?
The hydraulic pressure technique for sinus elevation is performed through a step-by-step procedure that includes:
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This technique is done through a crestal approach. The implant dentist mainly uses sinus burs, condensers, and water lift or aqua systems to create hydraulic pressure for elevating the sinus floor.
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The aqua system uses an aqua lifter that triggers an injection of approximately 1 cc of saline into the prepared implant osteotomy site. The implant dentist or the oral surgeon does saline infusion until the sinus membrane is lifted or raised to the desired level.
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Sinus elevator instruments are then subsequently used in order to detach the Schneiderian membrane from the underlying bone. Once this sinus augmentation is completed, bone grafting is achieved successfully with the help of a PRF (platelet-rich fibrin) clot or by utilizing only bone augmentation materials.
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If the dental surgeon offers the option of immediate implants, that is, when augmenting the sinus and performing the bone grafting procedure, if an implant is inserted in this osteotomy site, then the initial implant stability needs to be measured by the dentist (for attaining the ideal insertion torque). On the other hand, suppose an immediate implant is not opted for by the patient, in that case, the bone height in both vertical and horizontal dimensions needs to be checked by regular dental follow-ups so that the area can heal ideally and be suitable for dental implantation.
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Flap margins are approximated by the surgeon post the sinus augmentation and bone augmentation techniques using either horizontal mattress sutures or interrupted sutures.
What Are the Post-operative Instructions Given to the Patient?
The post-operative instructions include:
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Post-operative instructions are given by the surgeon or the implant dentist for the site to heal correctly, and antibiotics and analgesic medication are prescribed post-surgery for five to seven days. Patients can be called later for removal of the sutures within two weeks.
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Soft diet and Chlorhexidine rinsing twice daily for up to two weeks also help relieve postoperative pain or avoid unnecessary stress upon the surgical site.
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Finally, after three to six months, dental implantation can be achieved successfully with an excellent long-term prognosis because adequate bone height would have been achieved. After three to six months, a second stage surgery can also be done in case an immediate implant had opted for can be done for fabricating the prosthesis, then after recording the clinical features through CBCT (cone-beam computed tomography) imaging.
Conclusion:
To counteract the clinical challenge of bone loss after tooth extraction and for long-term achievement of good bone height and stability in the posterior maxillary region, the hydraulic pressure sinus augmentation technique is now an acceptable standard of sinus floor elevation. Again, following the post-operative instructions precisely will help in the fast healing.
