Original study - ZZI 01/2016

Measurement of implant stability increment after internal and external sinus floor elevation using resonance frequency analysis

Introduction: This study aimed to investigate whether the secondary implant stability is significantly higher in regions in which an internal sinus floor elevation (ISFE) procedure has been carried out compared to those regions where an external sinus floor elevation technique (ESFE) was applied. In addition, it aimed to ascertain whether the increase in primary implant stability relative to secondary implant stability is higher in regions where primary stability was initially low. Resonance frequency analysis (RFA) was utilized to compare primary and secondary implant stability, as well as the increase in stability between implants inserted by ISFE and those inserted by ESFE procedures.

Material and methods: The study population included 39 patients (25 women, 14 men) at a mean age of 60.3 ± 10.6 years. In total, 70 implants were inserted in the posterior maxilla region, 35 of these by internal and the other 35 by external sinus floor elevation technique. Immediately after insertion, the first measurement of primary stability was taken by RFA, using an Osstell device (Osstell, Gothenburg, Sweden). The second measurement was taken after an individually defined period at the point of re-entry.

Results: The implant stability measured by RFA at the point of implantation in the group with external sinus floor elevation was ISQ 65.6 ± 6.9. In the group with internal sinus floor elevation, it was ISQ 68.9 ± 1.4. The result shows a statistically significant difference (p = 0.035). Implants in the group with internal sinus floor elevation showed a mean measurement of ISQ 74.5 ± 1.7 after healing. Therefore, the secondary stability in this group was slightly lower than in the group with external sinus floor elevation, at ISQ 75.2 ± 3.8.

This difference, however, is not statistically significant. The increase in stability was higher in the group with external sinus floor elevation (ISQ 9.6 ± 5.2) compared to the group with internal sinus floor elevation (ISQ 5.6 ± 1.2).

Discussion: Within the limits of the study it can be stated that the secondary implant stability in regions in which an internal sinus floor elevation procedure has been carried out is not significantly higher than in those regions where an external sinus floor elevation technique was applied. A higher increase in stability has been demonstrated in regions where primary stability was initially low, i.e. in the group of implants with external sinus floor elevation.

Keywords: secondary implant stability; external sinus floor elevation technique; internal sinus floor elevation technique; increment in primary implant stability; resonance frequency analysis

Cite as:

Huy C, Weinhold O, Gehrke P: Measurement of implant stability increment after internal and external sinus floor elevation using resonance frequency analysis. Z Zahnärztl Implantol 2016; 32: 44–58

DOI 10.3238/ZZI.2015.0044–0058

Introduction

Dental implants not only serve for functional rehabilitation of partially dentate or edentulous patients but they also improve their aesthetics and phonetics. Implants in the posterior maxillary region are often placed where bone quality and quantity are inadequate.

The often limited vertical bone and the prevailing Misch [18] grade D3 and D4 bone quality not infrequently render implant insertion in the posterior maxillary region difficult. A residual vertical bone height of 6–8 mm is required [11, 19, 25]. The sinus floor elevation technique has become established in implantology to allow safe implant insertion despite the poor initial conditions.

A distinction is made between a one-stage procedure in which the implant is inserted simultaneously with the sinus lift and the two-stage procedure, when implantation takes place only after the augmented bone has healed [11].

External sinus floor elevation is a very predictable operation method for insertion of dental implants where bone is limited. If it is performed correctly, the same secondary stability can be expected as with implantations performed without this operation technique.

In the conventional lateral fenestration technique, which goes back to Tatum and was modified in subsequent years, access is through the facial sinus wall [30]. Following dissection of the vestibular mucosa, a window is opened in the wall of the sinus with a (diamond) round bur or piezosurgery.

The sinus mucosa is dissected carefully off the bone with special elevators, creating a subantral space toward the sinus cavity for the augmentation material. This space is now filled with bone and bone substitute. A membrane is placed to cover the augmentation material before the mucoperiosteal flap is reapproximated (Fig. 1, 2).

If a crestal approach is chosen to maximize the vertical bone, this procedure is called internal sinus floor elevation (ISFE). According to Summers, this procedure is also known as the osteotomy technique [29]. Primary implant drilling is first performed. Using special osteotomes of different diameters which are tapered with blunt ends, the bone is compressed in front of the instrument tip and at the same time pushed toward the sinus floor, leading to elevation of the sinus mucosa without perforating it. The osteotomes are advanced using a hammer. The new space can be filled with autologous bone or bone substitute [24].

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