Placing implants with insufficient bone height: complementary surgical techniques
Dental implants are always the same; what varies is the technique used to place the implant, which depends on the patient’s vertical bone height. Keep reading to find out more about the different techniques.
Maxillary sinus elevation
There are two different techniques (these techniques are used to increase vertical bone height and only treat the upper jaw).
Caldwell-luc techniqueCaldwell-luc sinus elevation (or surgical technique) is a surgical operation to gain access to the sinus cavity through a lateral window (Caldwell-Luc approach). An incision is made in the soft tissues to create a flap that exposes the anterior wall of the maxillary sinus. Once this bone is exposed, an osteotomy is performed with a drill with a round diamond bit to open a “window” into this wall. Once this opening is large enough to access the sinus membrane, the “window” is fractured inward so that its upper edge acts as a hinge, resulting in the apical shifting of maxillary sinus floor.
During this delicate procedure, care must be taken to not perforate the Schneiderian membrane, which must be slowly separated using instruments specially designed for this purpose, so that it can be positioned along the bone “window” to form part of the newly raised space of the maxillary sinus. Once the bone membrane has been repositioned with the Schneiderian membrane, the bone graft material is placed inside the maxillary sinus. Depending on each patient’s clinical situation, the implants may also be placed at the same time.
Finally, before suturing the flap, a barrier membrane will be placed to isolate the surgical cavity, a technique used to excludeconnective tissue from the flap.
Depending on whether the dental implant is placed at the same time, the Caldwell-luc or surgical technique can be categorized as:
- Immediate: implants are placed at the same time the augmentation is performed.
- Deferred: implants are placed at least 6 months after the augmentation is performed.
The choice of one technique or another should be based on the preoperative bone height available and the possibility of placing the implant(s) with primary stability.
Indications for the Caldwell-luc techniqueWhen we want to augment the vertical bone height in the posterior area of the jaw in the area underlying the maxillary sinus to make the placement of implants equal to or greater than 10 mm² possible.
Osteotome or Summers Technique (crestal elevation)
Osteotome or Summers Technique (crestal elevation) is used when the sinus floor requires a more conservative lift.
Crestal elevation is a surgical approach that provides for a partiallift of the floor of the maxillary sinus, which can also be lifted in multiple spots depending on the extent of the edentulous ridge and the number of implants that will be placed.
This type of approach is currently used for partial edentulism of the lateral arches. At this level the bone quality is often not high enough (class II and IV) to create problems of primary stability of the implants. Moreover, the fact that the implants are shaped from cylindrical to conical (in the shape of the root) makes it possible to use them for the bone expression and compaction in order to obtain greater primary stability.
The methodology is indicated when the height of the residual bone crest is at least 5 mm in height and 6 mm in thickness, in order to obtain the primary stability of the implant.
In the past, using the crestal approach to elevate the maxillary sinus had more limited indications in relation to a lateral lift, which is the other surgical alternative used when the sinus requires greater elevation. This is because the implants used in the past had a smooth surface and had medium to long-term implant survival that depended enormously on their length.
Today, sinus lifts using the crestal approach has had growing success, due to the development of implants with a surface that guarantees a higher percentage of bone implant contact (BIC) which allows medium to long-term clinical success, even with shorter implants.