Lateral Approach Sinus Floor Elevation Surgery

Introduction:

The reason for the implementation of lateral approach sinus floor elevation or LASFE technique by implant dentists is the need to achieve adequate crestal height to accommodate dental implants in the maxillary segment (within the upper posterior jaw). The most common detrimental effect of tooth loss, whether it is natural tooth loss or post-extraction, is that there is both alveolar remodeling of the bone as well as maxillary sinus pneumatization that takes place continuously. Hence this post-extraction or post-natural tooth loss bone remodeling is what is responsible for a significant reduction in the horizontal and vertical height of the bone crest that is edentulous that is post tooth loss. There are many ridge preservation techniques adopted in implant dentistry by the dental operator to maintain the adequacy or proportionate structure of the bone volume. In fact, preoperative assessment by three-dimensional radiographic modalities like CBCT (cone beam computed tomography) before dental implants by the operator is a primary factor for long-term dental implant success. However, even ridge preservation techniques may not always be helpful in achieving sufficient bone height; that is more so complicated because of the sinus pneumatization issue in the maxillary molar regions where a dental implant is needed to replace the missing tooth.

What Is Lateral Approach Sinus Floor Elevation (LASFE)?

This technique of LASFE was first proposed by Tatum and is derived or based upon the principle of the Caldwell Luc operation in the oral and maxillofacial surgery field. This technique originally proposed by Tatum has then been modified by several authors and clinicians dependent on a patient-centric approach. Research indicates in recent years that the insertion of implants showed long-term success rates and satisfactory clinical outcomes with good primary stability (95 % surgical rate at five-year intervals post loading). The use of piezoelectric bone surgery for this technique is an important development in the field of implant dentistry to avoid sinus membrane perforation, which remains the most common complication associated with the surgery and also, in turn, reducing the risk of postoperative sinusitis as a consequence of sinus membrane perforation. Hence, the major implication of this advanced lateral sinus floor elevation technique, preferably now recommended by implant dentists by piezoelectric surgery modality, is considered a good regenerative option for maintaining the acceptable inter-arch relationship and achieving good residual bone crest height in the posterior maxilla. Also, with the advent of piezoelectric bone surgery, the risk of membrane perforation of the sinus is also significantly reduced. Piezoelectric bone surgery (PBS), being an ultrasonic form of bone-cutting, has a great advantage in current-day clinical practice. This is because the piezoelectric tips utilize the micro-vibrations that allow for selective bone cutting control, precision in the osteotomy site preparation, and, most importantly, overall enhanced control. Hence LASFE is currently recommended to be practiced with piezoelectric bone surgery for the best results of predictability indication for long-term survival outcomes and decreased postoperative complications after modulating the bone crest height. Conventional osteotomy methods can also do LASFE, that is, through conventional drilling and conventional rotary instruments used for lateral sinus floor elevation.

What Are the Exclusion Criterion for LASFE?

The following are the contraindications for LASFE:

• Systemic diseases.

• History of radiotherapy.

• Immunosuppressive patients.

• Patients on bisphosphonate drug therapies.

• Pregnancy.

• Psychotic patients.

• Substance or drug abusers.

• Heavy smokers.

• Chronic alcoholism.

• Uncontrolled diabetes.

• Patients on long-term antibiotic therapy prior to dental implantation.

• Active periodontal disease.

• Patients with a lack of opposing dentition or missing opposite prosthesis or tooth.

What Is the Procedure for Lateral Wall Elevation?

There are three different forms of surgical techniques employed through PBS in the sinus floor elevation with a lateral approach, it includes:

• Lateral Bone Window Reflection Technique: In this, the lateral bone window is eventually reflected after outlining into the sinus cavity.

• Lateral window outlining and removal.

• Lateral wall consumption makes the membrane visible under the bone layer and then outlines the lateral window.

Using any of these three approaches, the maxillofacial surgeon or the dental implantologist will perform the following procedure.

• Firstly a full-thickness mucous periosteal flap would be elevated, and then a bony window will be created through any of the three techniques mentioned above in the case of PBS. This is also known as the procedure of lateral sinus wall antrostomy when used with conventional rotary instruments.

• The bony window is created on the wall with the help of round diamond or carbide burs, and without damaging or causing any perforation to the sinus membrane, the surgeon will elevate the sinus floor. The sinus floor is eventually elevated after reflection, and the surrounding bone wall elevation is also done using manual curettes.

• Bone substitutes or bone graft biomaterials are then placed as the last step for regeneration of bone before dental implantation. Autogenous bone grafts are the gold standard of choice usually, but xenografts, allografts, or alloplastic biomaterials also can be used as bone grafting substitutes that eventually promote bone regeneration for allowing the insertion of dental implants in this area of adequate crest height and length.

Postoperative complications need to be avoided like sinus membrane perforation, neurovascular bundle injury to the infraorbital nerve, adjacent teeth devitalization, or any hemorrhagic events. Care should also be taken to prevent the implant from dislocating into the sinus cavity. The most common postoperative complication, as discussed earlier, is sinus membrane perforation which can be prevented to a significant extent by piezoelectric bone surgery.

Conclusion

Be it conventional or piezoelectric bone surgery methods, the lateral approach sinus floor elevation (LASFE) is useful for improving bone crest height and augmenting new bone substitutes within the area prior to dental implantation for improving long-term success outcomes in dental implant patients.