Clinical and radiographic outcomes following transcrestal maxillary sinus floor elevation with injectable xenogenous bone substitute in gel form: a prospective multicenter study

Abstract

Purpose: To investigate clinical and radiographic outcomes of transcrestal maxillary sinus floor elevation performed with an injectable xenograft in gel form, analyzing general, local and surgical variables possibly influencing the results.

Methods: Patients with residual crestal height < 5 mm underwent transcrestal sinus floor elevation with xenograft in gel form to allow the placement of a single implant. Simultaneous implant placement was performed when primary stability was ≥ 15 Ncm. Graft height was measured immediately after surgery (T0) and after 6 months of healing (T1). Univariate and multivariate regression models were built to assess associations between clinical variables with implant survival and graft height at T1.

Results: 71 patients underwent transcrestal sinus floor elevation and 54 implants were simultaneously placed. Delayed implant placement (at T1) was possible in 5 cases out of 17 (29.4%), whereas in 12 patients (70.6%) implant insertion was not possible or required additional sinus grafting. Implant survival rate, with a follow-up varying from 12 to 32 months after loading, was 100%. Mean pre-operative bone height was 3.8 ± 1.0 mm, at T0 was 13.9 ± 2.2 mm and at T1 was 9.9 ± 2.8 mm. Bone height at T1 was negatively influenced by membrane perforation at surgery (p = 0.004) and positively influenced by immediate implant insertion (p < 0.001).

Conclusions: Transcrestal sinus floor elevation performed with injectable xenograft gel resulted in 100% implant survival rate. However, immediate implant insertion seems a crucial factor to preserve vertical bone gain: one-stage technique seems to be the most predictable approach to optimize clinical outcomes with this approach. Trial registration clinicaltrials.gov, NCT05305521. Registered 31 March 2022-Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT05305521 .

Keywords: Gel graft; Maxillary sinus augmentation; Transcrestal approach.

Fig. 1

Direct visual check of Schneiderian membrane integrity after crestal osteotomy performed with specific burs for transcrestal sinus approach

Fig. 2

Syringe of xenogenous porcine bone substitute in gel form with stainless steel insert to facilitate graft injection

Fig. 3

After performing crestal osteotomy and checking the Schneiderian membrane integrity (A), the graft is directly injected into the sub-antral space (B)

Fig. 4

Pre-surgical CBCT with cross-section showing a narrow sinus anatomy and RBH < 5 mm (A) and panorex image highlighting the presence of a sharp Underwood septum (B). Post-operative CBCT with cross-section showing abundant amount of gel graft apically to implant apex to counteract the expected shrinkage during the healing phase (C) and panorex confirming sinus membrane integrity (D)

Fig. 5

CBCT cross-section images taken presurgically (A), at T0 (B) and T1 (C) showing the “tent-pole” effect of the implant apex

Fig. 6

Periapical radiographs taken immediately after transcrestal sinus floor elevation without simultaneous implant insertion (A) and after 6 months of healing (B): an evident shrinkage of the regenerated volume is present