Study context and objectives

In the posterior maxillary sectors, residual bone atrophy frequently requires a sinus floor elevation to allow for long-term implantation. Although crestal elevation assisted by piezosurgery has established itself as an effective minimally invasive approach to limit membrane complications, the benefit of combining biomaterials with platelet concentrates remains a major subject of clinical discussion.

This randomized clinical trial specifically aims to evaluate the contribution of demineralized freeze-dried bone allograft (DFDBA) combined with concentrated growth factors (CGF) during a crestal sinus lift procedure. The authors compare this approach to the exclusive use of CGF, analyzing dimensional variations of the ridge, primary and secondary stability of simultaneously placed implants, as well as osteopontin (OPN) levels in the peri-implant crevicular fluid.

The hypothesis tested is based on the fact that the addition of DFDBA could optimize vertical bone gain and stimulate early regenerative activity, measured by OPN kinetics, compared to the use of CGF as the sole filling material.

Methodology: a comparative randomized clinical trial

This randomized clinical trial was conducted on 20 implant sites in the posterior maxilla requiring indirect sinus floor elevation. The objective was to compare the efficacy of Concentrated Growth Factor (CGF) used alone or combined with a bone allograft.

The sites were randomly divided into two experimental groups:

• Group A (n=10): Piezosurgery-assisted crestal sinus lift with addition of CGF and demineralized freeze-dried bone allograft (DFDBA).
• Group B (n=10): Piezosurgery-assisted sinus lift using CGF as the sole grafting material.

The protocol included simultaneous implant placement for all sites. The evaluation of results was based on three analytical pillars:

• Imaging: Measurement of vertical bone height (VBH) and bucco-palatal width (BPW) by Cone-Beam (CBCT) at inclusion and at 6 months.
• Implant stability: Measurement of the Implant Stability Quotient (ISQ) at the time of placement and at 3 months.
• Biochemical analysis: Measurement of osteopontin (OPN) levels in the peri-implant crevicular fluid via ELISA method at 15, 45 and 90 days post-surgery.

Data were subjected to statistical analysis with a significance level set at p < 0.05.

Analysis of bone gains and implant stability

Both crestal piezo-surgery protocols yielded favorable clinical and radiographic results. However, the comparative analysis at 6 months reveals significant disparities between the use of CGF alone and its association with allograft (DFDBA).

Parameter (at 6 months)	Group A (CGF + DFDBA)	Group B (CGF alone)	Significance (p)
Vertical Bone Height (VBH) gain	Superior (Significant gain)	Lower than Group A	p < 0.05
Bucco-palatal width (BPW)	Relatively stable	Significant reduction	p < 0.05
Implant Stability Quotient (ISQ)	Significant increase	Significant increase	p < 0.05 (intra-group)

Significant increases in vertical bone height (VBH) and implant stability (ISQ) were observed in both groups over time (p < 0.05). However, group A demonstrated a significantly greater vertical bone gain than group B at the 6-month follow-up.

Osteopontin (OPN) Kinetics

Biochemical evaluation of the peri-implant crevicular fluid shows more intense regenerative activity when using the combined CGF and allograft. Levels of osteopontin, a key marker of early bone formation, increased in both cohorts during the healing phase.

• Superiority of Group A: OPN levels were significantly higher in the CGF + DFDBA group at all measurement intervals (15, 45, and 90 days) compared to the CGF group alone (p < 0.05).
• Temporal evolution: A progressive increase in OPN levels was recorded throughout the follow-up, suggesting continuous bone metabolic activity during the first three months.

In terms of implant stability, although both groups achieved satisfactory ISQ values at 3 months, the addition of DFDBA appears to correlate with a more robust biological response, as evidenced by the higher concentration of bone biomarkers.

Analysis of clinical and biological performance

The results of this randomized clinical trial highlight the superiority of combining CGF (Concentrated Growth Factor) and allograft (DFDBA) in crestal sinus lift procedures. While both protocols secured by piezosurgery allow for simultaneous implant placement, the addition of DFDBA to CGF generates a significantly greater vertical bone gain at 6 months (p < 0.05). This difference is explained by the structural stability provided by the allograft, which prevents the collapse of the sinus membrane and the resorption of the fibrin clot.

Biochemically, the marked elevation of osteopontin (OPN) levels in the peri-implant crevicular fluid of group A confirms more intense osteoblastic activity and bone remodeling from the first 15 days. OPN, a key protein in the initial mineralization phase, appears to be a reliable indicator of the regenerative dynamics induced by the biomaterial-growth factor mixture.

Limits and perspective

Although robust due to its randomized design, the study presents a small sample size (n=20 sites) and a follow-up limited to 6 months. Furthermore, the significant reduction in bucco-palatal width observed in the CGF-only group suggests that without a bone substitute to maintain volume, long-term dimensional stability could be compromised, despite satisfactory initial implant stability (ISQ) in both groups.

Summary of results

This 20-site randomized clinical trial shows that combining CGF with an allograft (DFDBA) during crestal sinus lift via piezo-surgery outperforms CGF alone in terms of vertical bone gain at 6 months (p < 0.05). Osteogenic activity, measured via osteopontin (OPN) levels in the peri-implant crevicular fluid, is significantly higher in the combined group at all follow-up intervals (15, 45, and 90 days).

In concrete terms, for the practitioner:

• Maximizing vertical gain: Adding the allograft to the CGF is recommended to achieve a greater bone volume and stabilize the bucco-palatal width, avoiding the reduction observed with CGF alone.
• Reliability of piezosurgery: This crestal elevation technique ensures increasing and satisfactory implant stability (ISQ) for conventional loading, while minimizing the risks of membrane perforation.
• Biological acceleration: The use of DFDBA stimulates non-collagenous proteins of the bone matrix earlier, promoting active peri-implant healing from the first two weeks.

In the posterior maxillary sector, bone atrophy often requires sinus floor elevation before implant placement. While the piezo-assisted crestal approach has become standard for its minimally invasive nature and the safety of the Schneiderian membrane, the choice of grafting material remains a subject of debate. This randomized clinical study, published in August 2026, compares the efficacy of concentrated growth factors (CGF) used alone or in combination with demineralized freeze-dried bone allograft (DFDBA).

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