Article

Feature Article
Nov 18, 2021 // 12 min read
An Update on Current and Innovative Materials and Techniques Used for Maxillary Sinus Floor Elevation Procedures
Yiqun Wu
Feng Wang
Wenjie Zhou
DOI: 10.3290/iti.fi.45636
Abstract

Currently, maxillary sinus floor elevation (MSFE) is the most predictable and regularly used procedure to increase bone volume in the posterior maxilla. This procedure is used in cases where residual bone height (RBH) is not sufficient for implant placement due to alveolar vertical bone loss and/or sinus pneumatization. MSFE can be performed through two main approaches: the lateral-window technique and the transcrestal sinus lift. In general, both approaches involve the placement of bone grafts in a space created by the elevation of the maxillary sinus membrane.

The materials and techniques used for MSFE are continuously developing to reduce patient morbidity, overall treatment times, and treatment complexity while providing predictable treatment outcomes. However, the high number of materials and techniques available to MSFE makes it difficult for the surgeon to select the most appropriate surgical approach and the product with the lowest risk of complications. The aim of this review is to summarize the available materials and techniques of MSFE used in current practice and to look at the application of several innovative materials and techniques in MSFE.

Sinus grafting materials

The aim of MSFE is to create vital bone that allows successful osseointegration of dental implants. Autogenous bone (AB) is the original material used in MSFE procedures. AB exhibits osteogenic properties due to the living cells and growth factors it contains, and presents the highest percentage of new bone formation compared to other osteoconductive bone substitutes (Hürzeler et al. 1997; Froum et al. 1997; Sanz et al. 2019; Al-Moraissi et al. 2019). However, the supply of AB is limited and complications at the donor site are frequent. Additional considerations include the resorption rates and the difficulty of maintaining adequate space under the membrane.

Bone substitutes such as allografts, xenografts, and alloplastic grafts have increasingly been used as alternatives. These bone substitutes have proven successful in MSFE, and the use of some grafting materials, such as xenografts in the sinus, is well documented in the literature (Starch-Jensen et al. 2018) (Figs 1a-c).

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Fig. 1a: De novo bone wraps are seen around the xenograft bone substitutes (Bio-ossTM)
Fig. 1b: New bone formation is observed in the alloplastic grafting area. The resorbed grafting material (β-tricalcium phosphate [CerasorbTM]) has left pores in the section
Fig. 1c: De novo bone formation is seen surrounding the alloplastic grafting substitutes. Ca3(PO4)2 (ReboneTM) is partially degraded and appears as a porous structure surrounding the new bone
Fig. 1a Fig. 1b Fig. 1c

Due to the continuing decrease in complications, the implant survival rates of MSFE with bone substitutes have been reported to be as high as those achieved using AB. Moreover, bone substitutes have no negative clinical effects on implant outcomes. It is noteworthy that the implant survival rate is not an accurate parameter for assessing the efficacy of bone substitutes because osseointegration is always present regardless of the bone substitute used (Figs 2a-g).

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Fig. 2a: Pre-operative panoramic radiograph showing limited bone height in the left posterior maxilla
Fig. 2b: Panoramic radiograph showing the high radiopacity of the alloplastic (β-TCP) 3 months after MSFE with simultaneous implant placement
Fig. 2c: At the 10-month follow-up, the elevated sinus floor remained above the apex of the implants, but the bone level was lower than at the 3-month follow-up
Fig. 2d: At the 15-month follow-up, bone level went down significantly and the implants protruded into the maxillary sinus
Fig. 2e: At the 4-year follow-up, further resorption of β-TCP was observed
Fig. 2f: At the 5.5-year follow-up, the resorption of β-TCP continued, but the rate of resorption was significantly lower than that of the previous two years
Fig. 2g: At the 7-year follow-up, β-TCP gradual resorption resulted in no bone contact with the implant apex and bone formation in the areas close to the native residual bone. The implants were still in site and performing well functionally
Fig. 2a Fig. 2b Fig. 2c Fig. 2d Fig. 2e Fig. 2f Fig. 2g

In this regard, the healing periods after staged grafting and the time intervals between simultaneous MSFE and the start of loading have varied widely between studies. It is not possible to draw conclusions regarding the optimal healing time of the graft material and implants before loading after MSFE. In clinical practice, the staged lateral-window approach always requires a healing time of 6 months or more before implant placement. When an implant is placed simultaneously with sinus grafting, implant loading is delayed until at least 6 months after surgery. Some clinicians believe that the combined use of AB and bone substitutes is associated with improved new bone formation compared to using bone substitutes alone and that this approach allows a shorter healing period.