Sinus lift (synonym: sinus floor elevation) refers to oral surgical procedures that build up the bony floor of the maxillary sinus (lat. : sinus maxillaris) with the goal of creating a load-bearing bed in the maxillary posterior region for implant placement (placement of artificial tooth roots). The maxillary sinuses are ventilated cavities lined with mucosa (mucous membrane), which are bounded at the bottom by a bony separating layer, the so-called sinus floor, from the oral cavity. Tooth extractions (tooth removals) result in the more or less pronounced atrophy (degradation) of the alveolar ridge (synonym: alveolar ridge; tooth-bearing portion of the jaw). After years of toothlessness and wearing removable dentures, the alveolar ridge and sinus floor can be so severely atrophied that the layer of bone separating the oral and maxillary sinuses is only a few millimeters, in extreme cases only one millimeter. If dental prostheses are planned for the posterior region of the upper jaw, which are to be supported by implants, the jaw bone must first be built up by means of a sinus lift in such severely atrophied sections of the upper jaw, so that implants can be placed. A large number of implants could not be successfully and stably placed without the preceding elevation of the sinus floor. For this purpose, it is not the bony interface itself that is elevated, but the so-called Schneider membrane (synonym: Schneiderian membrane; mucous membrane-bone skin layer lining the maxillary sinuses). Autogenous bone and/or bone substitute materials are inserted into the surgically created cavity (insertion osteoplasty). Autogenous bone is still the gold standard. Postoperatively (after surgery), the augmentation material (Latin : augmentatio = augmentation; material used to raise the sinus floor) is gradually degraded and – depending on the material – partially or completely replaced by newly formed bone.
Indications (areas of application)
- Atrophy (degradation) of the bony floor of the maxillary sinus (the maxillary sinus).
Before the operations
- Dental volume tomography (DVT) or computed tomography (CT) to rule out pathologic (pathological) findings and assess (evaluate) the bony structures
- Risk disclosure
- Clarification about
- Alternative therapy measures
- The process flow
- The postoperative behavior
The operation procedures
I. External sinus lift (external sinus lift) – one-stage procedure.
The indication for sinus lift with simultaneous implant placement is given with a ridge height of at least 4 mm, if primary stability of the implant can be achieved based on bone quality. After six to nine months, the load-bearing capacity of the implant permits restoration with a prosthetic superstructure. Procedure:
- Local anesthesia (local anesthesia) of the surgical area – As a rule, general anesthesia (general anesthesia) is not required, but may be performed in individual cases, such as anxiety patients.
- Incision for the formation of a mucoperiosteal flap (mucosa-bone skin flap) not on the alveolar ridge, but slightly offset to palatal (towards the palate).
- Detachment of the mucoperiosteal flap from the bony base to the vestibule (oral vestibule).
- Lateral osteotomy (surgical transection of bone or the excision of a piece of bone) of the maxilla – Preparing a vestibular bone window of about 1 cm² in the maxillary sinus wall with at least 1 mm distance from the alveolar ridge – The sartorius membrane is spared here, the bone carefully prepared with special sinus lift instruments (raspatory).
- Drilling for the implant
- Implant insertion
- Filling of the cavity with bone and/or bone substitute material with elevation of the Schneider membrane.
- An absorbable membrane is used to stabilize and completely cover the augmentation material and also supports bone regeneration (GBR – Guided Bone Regeneration).
- Repositioning (bringing back to a (near) normal position) of the mucoperiosteal flap via membrane and implant.
- Saliva-tight wound closure with single button sutures.
II.External sinus lift – two-stage procedure
Apart from the implant placement, which must be dispensed with and may be performed at the earliest six months after the sinus lift, the procedure corresponds to the one-stage procedure. The indication is for ridge heights of less than 4 mm, since primary stability of the implant cannot be achieved with such a low bone volume. III. Internal sinus lift (internal sinus lift, “transalveolar” sinus lift)
Unlike the external sinus lift, this procedure does not require an osteotomy (cutting) of the maxillary sinus wall. It is indicated when an improvement in bone density is useful to increase the primary stability of the implant and only a small amount of additional vertical bone is required. Procedure:
- Local anesthesia (local anesthesia) of the surgical area – As a rule, general anesthesia (general anesthesia) is not required, but may be performed in individual cases, such as in anxiety patients.
- Incision for the formation of a mucoperiosteal flap (mucosa-bone skin flap) not on the alveolar ridge (tooth-bearing portion of the jaw), but slightly offset to palatal (palatal).
- Detachment of the mucoperiosteal flap from the bony base to the vestibule (oral vestibule).
- Prepare the implant site first with thinner pilot drills up to 2 mm in front of the sinus floor.
- Step-by-step preparation with bone condensers of increasing diameter (instruments for bone compaction) with compaction of the bony implant environment and gradual, dome-shaped lifting of the Schneider’s membrane.
- Insertion of bone graft substitute (KEM), which is not compressible (compressible) under further “lift” of the Schneider’s membrane.
- Implant insertion (implant insertion).
- Repositioning (bringing back to a (near) normal position) of the mucoperiosteal flap over the implant.
- Saliva-tight wound closure
After the operations
- Postoperative X-ray control (OPG: orthopantomogram).
- Once again education about the behavior in the wound healing phase – ban on sniffing for two weeks, so as not to stress the surgical area by overpressure in the maxillary sinus and use of decongestant nasal drops during this period.
- Suture removal 10 days postoperatively (after surgery).
- For the same reason up to four weeks postoperatively neither diving nor transatlantic flights.
Possible complications
- Perforation (puncture) of the Schneiderian membrane.
- Wound infection
- Postoperative swelling
- Hemorrhage
- Post-bleeding
- Postoperative pain
