What is antrostomy procedure during lateral sinus lift?

May 04, 2021

What is antrostomy procedure during lateral sinus lift?
Antrostomy bone window
Lifting the sinus bony wall and accessing the maxillary sinus

An antrum or sinus refers to one of the many hollow spaces present in the body. These hollow spaces may be present on the face in pairs or unpaired. They play a key role in modulating the voice, maintaining the dynamic weight of the skull, moisturise the inner linings of the nasal cavity and protect it from foreign microbes.


The maxillary sinus is the largest of these sinuses. It is present under the orbit (bone around the eye), shares a side with the nose and is above the posterior (backwards) part of the upper jaw bone. The relation of the maxillary sinus to the maxilla and the corresponding teeth in that region (molars) have a harmonious relation that contribute in maintaining the vertical height of the face. When the molars are lost, the part of the maxillary bone that held the tooth begins to heal and remodel itself. However, in the process, it gets gradually resorbed. This leads to the bone getting thinner, making it less favorable to accept an implant to replace the lost tooth. This makes the maxillary sinus come in close approximation to the upper jaw bone.


An implant primarily adheres itself by binding with the bone, a process known as osseointegration. But when there is no sufficient bone available, like in this case where the bone has resorbed due to loss of tooth, osseointegration becomes a challenge. Hence, bone grafting materials, that mimic the lost bone is placed to replace the lost bone height. This material is placed after two surgical intervention procedures, namely, antrostomy and sinus lift.


A sinus lift is a procedure where a part of the maxillary sinus is lifted in order to make space for the bone graft material to be placed. This procedure is facilitated through another procedure called antrostomy. Literally, 'antro' refers to the sinus, and 'stomy' indicates making an artificial opening. An antrostomy helps in enlarging the access to the maxillary sinus. Introduced in the 1980s, this technique is not only useful in sinus lift procedures but in other surgeries pertaining to the maxillary sinus too.


An antrostomy procedure cannot be done without anesthetising the area of the maxillary sinus. Once the administration of the anesthetic agent is complete, the dental surgeon begins to incise the maxillary sinus such that a window-like preparation is done. When the needed cuts are placed, a flap is formed which is approximately (20 x 15) mm in dimension. This flap raised with the help of an instrument called elevator. The raising of this flap exposes the maxillary sinus. Now the surgeon outlines the amount of sinus that needs to be pushed inside or lifted. Once the membrane (covering) of the sinus is detached from the bone, it is elevated (lifted). Once it is lifted to the needed height, the patient can be asked to do some deep breathing in order to check the integrity of the new position of the sinus. The final positioning of the maxillary sinus is fixed and the bone graft material is placed in the new area thus formed.


Another way to perform an antrostomy is by raising a flap only in the crestal ridge. This is the elevated part of the arch of the jaw where the teeth are positioned. However, this technique is done only when there is sufficient bone height. Instruments called the osteotomes and a few drill-like instruments are used in this procedure to cut the dense bone.


Over the years, advancements in sinus lift procedures have seen practitioners utilize techniques like piezoelectricity, balloon elevation and minimally invasive techniques in order to lift the sinus. Placement of an implant can be immediate or can be after as long as 6 months depending on patient's various heath factors. Once the graft maturation is complete, it becomes easier to place the implant within the bone graft.


Following a sinus lift, a range of post-operative care instructions needs to be followed by the patient. Firstly, the head should be elevated while sleeping on the immediate night after the surgery. Next, the patient needs to be on a soft diet for the next 2 weeks. If there is any nasal bleeding in the first couple of days after the surgery, the patient must not panic and should follow-up with the surgeon. A swelling below the eye is not rare. Ice/cool pack application can help in subsiding it. An antibiotic and analgesic regime as prescribed by the surgeon must be followed. If the patient wants to sneeze, he or she should keep the mouth open while doing so. No pressure should be exerted in the sinus area. Hence, the patient must not resort to smoking, swimming, playing wind instruments, lifting weights, travelling through aeroplane, drinking with straw, consuming carbonated drinks, etc. Complications like sinusitis, abnormal formations in the sinus, profuse bleeding in the sinus, tearing of the sinus membrane need to be addressed immediately.


Following the loss of a molar, subsequent reduction in vertical bone height and exertion of positive pressure by sinus can make it challenging for the oral surgeon to place an implant. An antrostomy makes sinus lift procedures more easier and precise. As the dental surgeon becomes more experienced, the amount of flap raised can be smaller and more conservative, once he or she is well-versed with the anatomy. Moreover, smaller flaps reduce the chances of post-operative complications. Thus, antrostomy can aid in the process of regaining the lost vertical height of the face.


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