Edentulism restored by means of implants Part 2 Sinus lift

Often bone width at the site of the upper molars is sufficient but bone height is inadequate for the instalment of implants. Such instances call for a sinus lift. This is a special maxillofacial surgery in the course of which a window is cut into the wall of the maxillary sinus with a Piezo (Piezo Med, W&H) and Schneider’s membrane is lifted to introduce bone graft material through the window and thereby to increase bone height.

What causes the decrease in bone height, bone resorption and bone decay at the level of molars?

• Inflammation associated with uncontrolled periodontal disease “eats up” the bone, and gingival atrophy causes bone decay leading up to the loss of teeth. Usually a lot of bone is destroyed in the process before a tooth drops out.
• In case of untreated carious teeth, the tooth is “open” for far too long a time and bacteria make their way into the root canal where they proliferate and migrate through the root tip to the maxillary sinus. The accumulated anaerobic bacteria and toxins produced by them cause inflammation and infection which is associated with bone resorption.
• Inappropriately root canal treated teeth develop pus pockets, or cysts around them. Inflammation, infection and the abscess forming around the root tips bring on a great extent of bone resorption compromising the success of the dental implantation.
• Following tooth loss the bone mass further deteriorates. When a tooth is lost and no implant is installed the bone begins to decay over time. In such cases we chew on the alveolar ridge, destroying and “flattening” the bone, rendering the subsequent instalment of an implant unfeasible due to the resulting bone deficiency.
• The anatomic properties of the maxillary sinus. Every individual is different and so are their anatomic properties. As we age the dimensions of the maxillary sinus increase. Different bone recessions and projections, septa develop which render a sinus lift increasingly more difficult. In such cases, were we to inert implants without a sinus lift, the maxillary sinus would incur damage. The inside of the maxillary sinus is lined by a membrane, the so-called Schneider’s membrane. The integrity and width of this membrane is essential during surgery, since if the maxillary sinus opens during the sinus lift, Schneider’s membrane is ruptured and no bone graft be performed.

Can a sinus lift provide a solution for everyone if bone height in the maxilla is inadequate for an implant?

Unfortunately no such universal solution exists, but the procedure may help a number of patients. Sinus lift requires a minimum bone height in the absence of which a much longer time is required to build up an appropriate bone height.

What conditions contraindicate the operation?

• Upper respiratory illnesses
• Seasonal allergies may indicate the postponement of the operation to a symptomless period.
• With polyps and other inflammations in the maxillary sinus a sinus lift can only be performed once such lesions have been eliminated by an otorhinolaryngologist.
• Smoking greatly compromises the success of the intervention.
• Tumour patients are advised against undergoing a sinus lift (due to radiotherapy and products containing bisphosphonates).
• Neglected oral hygiene (unsanitary conditions in an infection-ridden oral cavity full of inflammations and abscesses).

A sinus lift can solely be performed in an inflammation-free, sound and clean maxillary sinus. This is why a CT scan is required to demonstrate any chronic lesions in the maxillary sinus.

Can an implant be installed simultaneously with a sinus lift?

With a CT scan bone height in the maxillary sinus can be determined exactly. If the height exceeds 4mm, a sinus lift can be carried out simultaneously with the implant surgery since this bone height can sustain an implant providing good primary stability until the bone graft material integrates and new bone forms inside the maxillary sinus around the implant.

When the height of residual bone is less than 4 mm, a two-stage surgery is required. This means that first only a sinus lift (bone graft) is performed, and implants are installed after 6 to 8 months’ healing time. With bone grafts this healing time is always at least 6 months. Once the implants are installed, another 4 to 6 months are required for the implants themselves to integrate, and then only can the preparation of the permanent replacement, implant crowns and bridges follow.

Does the implant surgery take much longer if a sinus lift is required?

No, today a sinus lift qualifies as a routine surgery, it only takes about 30 minutes’ extra time over the normal time of surgery. At our clinic a W&H Piezo Med device is used, which is an efficient precision instrument allowing for a minimally invasive intervention. Patients heal faster and are in for less of a trauma than in a bone drilling procedure carried out by a conventional rotary instrument. The operation of the vibrating diamond tip of the piezo is atraumatic and cuts the bone with remarkable ease with scarcely any bleeding, which puts it on the cutting edge of technology. The piezo makes a “squeaking” sound and vibration, very much like the sound of a plain ultrasound tartar removal.

What kind of bone graft material is used in case of a sinus lift?

The bone graft materials used at our clinic can be both human and animal (bovine) derived powdered bone graft to which bone scrapings of the patient’s own are added. In the course of the surgery we may obtain bone from the patients themselves (autologous bone) by drilling out a piece of bone and grinding it or collecting drilled away bone dust clinging onto the drills, or simply by scraping off a little bone using a Safe Scraper (bone scraper). Purchased human bone graft material (allograft) is obtained from hip bone and shankbone, which is ground and sterilised, whereas animal derived bone graft is of bovine origin.

What to expect following a sinus lift?

• The operative area may swell. A little bit of icing may help but only for a short time as cold causes blood circulation to decrease at a time when healing and nurturing blood is badly required.
• Very rarely a large extent of hematoma may develop which may look “alarming” when the patient wakes up as the inflammation shifts towards the eyes while they sleep, but it resolves during the day with movement and walking.
• Bleeding in the mouth and nosebleeds may occur for a day or two. “Leakage” is normal but with greater amounts of blood and if the bleeds fail to stop after a day, you should immediately return in order for us to “reinforce” the sutures by placing in additional sutures to “block” the little bleeding veins. This is not a pleasant intervention but necessary at all events!
• IMPORTANT NOTICE: following sinus lift it is forbidden to blow your nose. In the event you sneeze do it with your mouth wide open and aloud so the maxillary sinus is relieved even of the smallest pressure. In the event of stuffy nose, use a nose spray and ensure “pressure-free”, easy nose breathing.
• Following antibiotic treatment we recommend probiotics for the restoration of gut flora.
• The surgeon will prescribe antibiotics and painkillers in order to prevent infections and pain. With antibiotics it is important to continue through with the regimen and not to stop it even once the symptoms have resolved.
• As a complementary therapy you may want to use saline nose sprays to moisten the nasal mucosa.
• An antiseptic mouth rinse may be used starting from the day after the surgery. Rinse with care, only streaming the liquid from side to side rather than doing a proper gurgling rinse.
• Removal of sutures is due 2-3 weeks following the intervention.
• Make sure you also take vitamin D during the healing period as over half the “people today” have a vitamin D deficiency. With insufficient exposure to sunlight an inadequate amount of vitamin D is produced. Vitamin D is vitally important in the improvement of bone mass quality and bone production.

We would like to stress that our patients experience little or no discomfort following a sinus lift.

What are the risks associated with the intervention?

The main risk associated with a sinus lift is the injury and rupture of Scnheider’s membrane separating the maxillary sinus from the bone. If the hole is small then the surgeon can easily cover it a PRF (Platlet RichFibrin) membrane or an absorbable collagen membrane (Lyopant) and continue with the surgery.

If the hole is large the surgeon covers the window on the maxillary sinus, suspends the surgery and Schneider’s membrane heals on its own. 4 to 6 months following healing a sinus lift can be attempted again.

As with any surgical intervention, a sinus lift also involves the risk of infection, however infinitesimal given that the patient receives antibiotics throughout.

Also rather infrequently, the bone graft material may not integrate into the surrounding bone mass for the aforesaid reasons and remains soft rendering the instalment of an implant impossible. If this be the case, everything needs to be cleansed and scraped and the whole procedure needs to be started over.

Can’t we resume the treatments earlier than 6 months?

With bone grafts it is vital to wait until the minimum 6 months’ healing time is complete. This is the minimum time required for the implants to osseointgerate/integrate into the surrounding bone mass and new bone to form. The surgeon will always say the minimum time required for bone formation but the actual time required may be a few months longer. However, the point is that the next treatment should occur no earlier than 6 months, but nor should the patient report for the next treatment after the lapse of several years…

CT scan of the patient picturing the maxilla and the 2maxillary sinuses at the two sides. The maxillary sinus is a sizeable black hollow filled with air. In the three smaller images below portraying the maxilla in cross section it is readily visible that we are dealing with an insufficient bone height of 6.46 mm which calls for a bone graft procedure (sinus lift).
Double sinus lift

 

Follow-up panoramic radiograph on completion of the upper bone graft (image of sinus lift = white bone mass in the maxillary sinuses) and upon the instalment of the 4 lower implants.

 

Follow-up radiograph after the instalment of the 8 implants into the maxilla with gingiva formers (healing abutments)

CT scan picturing the maxilla and maxillary sinus in which the bone height and width can be examined in 3 dimensions. In the bottom 3 images it is readily visible that we have rather a low bone height of around 2 mm which calls for a bone graft (sinus lift), if we are to perform an implant surgery.

 

 

Follow-up panoramic radiograph after the upper left bone graft (sinus lift).

Follow-up panoramic radiograph of the implants inserted into the upper left sinus lift.

Keywords: Sinus lift, bone graft, bone graft material, autologous bone graft, Piezo, minimally invasive oral surgery, PRF, A-PRF, implant, implantology