Sinus lift
Sinus lift refers to a special surgical method in maxillary surgery with which the bony floor of the maxillary sinus ( maxillary sinus ) is thickened. The sinus lift is one of several procedures for building up the jaw .
anatomy
The maxillary sinus is bounded on the inside by the bone wall separating the nasal cavity, on the side on the outside by the bone wall of the cheek and the zygomatic root. Upwards, a thin layer of bone separates the large maxillary sinus from the eye socket , the floor of which it forms. Finally, at the bottom, the so-called sinus floor houses the tooth roots of the small ( premolars ) and large ( molars ) molars . In this way, it represents the bony separation of the maxillary sinus from the oral cavity.
After removal ( extraction ) of one or all of the molars, it can be observed that the thickness of the sinus floor decreases more or less significantly due to the disappearance ( atrophy ) of the bone. The reason for this atrophy is unanimously seen in the lack of internal chewing force on the bone. But aspects of how the teeth feed this bone layer also play a role. It can be seen here that the living tooth is in a mutual nutritional dynamic with the bone that supports it.
Are all molars removed and on the mouth side by a located there on the gum overlying dentures replaced, causing the chewing pressure of the prosthesis to the sinus floor an additional bone loss. In this way, after years, the bone layer of the sinus floor gradually atrophies into a thin lamella, sometimes only 1 mm thick or even less.
Importance to the use of dental implants
Without the sinus lift operation, a large part of all implantological interventions in the upper jaw with the use of cylindrical implants could not be carried out with reliable and acceptable chances of success, because the bone supply found is so small that even small and short implants are so limited due to the late restoration that is generally used cannot find sufficient support.
It is obvious that a thin layer of bone is not thick enough to accommodate a cylindrically shaped implant body with excess bone on all sides. A predominant part of this implant would come to stand in the air-filled maxillary sinus, while the thin bone layer cannot give the implant the necessary support. The aim of the sinus lift operation is to thicken the bone layer of the sinus floor, lifting the inside of the maxillary sinus mucosa in the manner described below . This process gave the surgical method its name. It was carried out for the first time by the American dentist and implantologist Hilt Tatum in the mid-1970s , published by him in April 1977 and is now considered the standard procedure in the field of implant surgery in dental implantology.
Surgical procedure
There are basically four methods of thickening the bone layer of the maxillary sinus floor:
- direct sinus lift (sinus floor elevation and augmentation)
- indirect sinus lift
- indirect sinus lift according to RM Frey
- Transcrestal Antro Membrano Plastie (balloon method)
The problem with all procedures is the initial stability of the implant. Therefore, the height and hardness of the jawbone in the maxillary posterior region is the only criterion for whether an implant can be placed during the sinus lift operation. If the initial stability cannot be guaranteed, the implant should be placed after the new bone has healed.
Direct sinus lift ( according to O. Hilt Tatum )
After exposing the lateral maxillary sinus wall by folding down the gums, the thin lateral maxillary sinus wall is weakened in a 1–2 cm² area by a circumferential line with a spherical diamond drill, so that it can be pressed in like an eggshell. The resulting cover is then folded up inwards and upwards together with the inner lining of the maxillary sinus ( Schneider membrane ) adhering to the inside (“ lifting ”), so that a more or less large cavity is created. Bone chips made from one's own or foreign bones (cattle, pigs, humans) or synthetic bone substitute material are then often inserted into this cavity . In the following months or years, this material is biochemically (mostly hydrolytically ) degraded, resorbed and replaced by newly growing bone (" replace resorption ", Axel Wirthmann), resulting in an overall osseous thickening of the maxillary sinus floor. In a second surgical step, the desired implant or implants are inserted into this then thickened bone layer.
Possible sequence of an external sinus lift with implantation in region 26
OPT before external sinus lift and implantation in region 26
DVT planning of external sinus lift and implantation in region 26
External sinus lift with implantation region 26 - ridge incision
External sinus lift with implantation region 26 - ridge incision and sulcus incision
External sinus lift with implantation region 26 - mucoperiosteal flap
External sinus lift with implantation in region 26 - representation of the buccal sinus wall
External sinus lift with implantation in region 26 - preparation of the buccal sinus bone window
External sinus lift with implantation in region 26 - opening of the buccal bone window with pusher
External sinus lift with implantation in region 26 - opening of the buccal bone window without perforation
External sinus lift with implantation in region 26 - preparation of the maxillary sinus mucosa without perforation
External sinus lift with implantation region 26 - Drilling the implant cavity with a pilot drill
External sinus lift with implantation region 26 - Drilling the implant cavity with a thick drill
External sinus lift with implantation region 26 - Drilling the implant cavity with the last drill
External sinus lift with implantation region 26 - screwing in the implant
External sinus lift with implantation region 26 - screwed-in implant with screw-in post
External sinus lift with implantation region 26 - screwed-in implant with healing screw
External sinus lift with implantation region 26 - bone augmentation with own bone (from drill chips)
External sinus lift with implantation region 26 - bone structure with own bone
External sinus lift with implantation region 26 - suturing the gums
External sinus lift with implantation region 26 - sutured gingiva after completion
Dental implant region 26 immediately after implantation and simultaneous external sinus lift
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Indirect sinus lift
Here, the drill hole of the cylindrical implant bed is brought up close to the inner lining of the maxillary sinus and then lifted mechanically with light hammer blows with another instrument. The borehole is then filled with foreign material or chips of the patient's own bone (crumbs) so that the material can spread below the inner mucous membrane of the maxillary sinus when the implant body is introduced. As a result, the part of the implant that is otherwise in the air in the maxillary sinus is surrounded with material, which is then subject to the biochemical decomposition mechanisms with simultaneous replacement by natural bone, just as with the direct sinus lift.
This procedure requires a certain thickness of the maxillary sinus floor layer (min. 4 mm), while the direct procedure can be carried out with a layer thickness of well below 1 mm.
Indirect sinus lift ( according to RM Frey )
The gums on the upper jaw are incised with a scalpel. The tissue is lifted and the bone is exposed. With the help of osteotomes , a bone block is mobilized which is not loosened from the Schneiderian membrane (lining of the sinus floor of the maxillary sinus) (vital bone). With this method, the Schneiderian membrane is lifted without damaging it with the instruments. In the same operation, a conical implant made of pure titanium is inserted. The side walls of the maxillary bone are compressed by the cone and the implant receives its primary stability. The osseointegration time is shortened by the mixture of blood and bone chips and the vital bone block . Bone substitute materials are not used in this method. This procedure can be carried out with a residual bone height of the floor of the maxillary sinus from 1 mm.
Transcrestal Antro Membrano Plastie (balloon method) ( after Benner, Bauer, Heuckmann )
This procedure is a specially developed technique to detach the maxillary sinus mucosa from the bony floor of the maxillary sinus in a minimally invasive manner (i.e. with minimal soft tissue damage) using a fluid-filled balloon catheter. Here, similar to the indirect sinus lift, the operation is transcrestal (through the alveolar ridge). A controllable drilling system is used to drill up to approx. 1 mm to the floor of the maxillary sinus. Then the remaining bone (approx. 1 mm) is advanced towards the maxillary sinus using a special osteotome. The mucous membrane of the maxillary sinus remains undamaged. This mucous membrane is then detached from the floor of the maxillary sinus using a fluid-filled balloon catheter. The volume and the detachment height of the mucous membrane can be precisely determined by the controllable filling of the balloon. Similar to the indirect sinus lift, this newly created space is filled with bone graft material via the access through the alveolar ridge.
This procedure can be performed regardless of the height of the jawbone and is very gentle on the patient.
Cost-benefit analysis
The slightly higher clinical success rate (implant survival time) of the direct sinus lift is put into perspective when the significantly higher costs are taken into account compared to the indirect sinus lift. From the patient's point of view, the higher invasiveness of the direct sinus lift should also be an important decision criterion. However, an indirect sinus lift is only promising if there is sufficient residual bone height.
Literature and Sources
- ↑ SS Wallace, SJ Froum: Effect of maxillary sinus augmentation on the survival of endosseous dental implants. A systematic review. Review. In: Ann Periodontol. Volume 8, No. 1, Dec 2003, pp. 328-343.
- ↑ S. Listl, CM Faggion: An economic evaluation of different sinus lift techniques. In: Journal of Clinical Periodontology . Volume 37, Number 8, August 2010, pp. 777-787, ISSN 1600-051X . doi: 10.1111 / j.1600-051X.2010.01577.x . PMID 20546083 .