Surface topography: a lever for regeneration in sinus lift?

The rehabilitation of the atrophied posterior maxillary bone often imposes a technical dilemma between the lateral approach and the transcrestal route, which is more conservative but demanding in terms of regenerative potential. While the choice of filling biomaterial is extensively documented, the direct influence of implant wettability on the volume of newly formed bone remains a major subject of clinical debate. The challenge is to transform titanium, a bioinert material, into a physiologically active surface capable of boosting osseointegration in grafted sites.

This 12-month monocentric clinical study, conducted on 25 participants, precisely evaluates the impact of a new nanometric roughness and super-hydrophilic surface compared to a conventional moderately rough surface. The objective was to quantify, through radiographic analysis, the variations in volume and height of regenerated bone after a transcrestal sinus lift using a collagenated hydroxyapatite graft.

The central hypothesis is based on the supposed bioactivity of these super-hydrophilic surfaces: by promoting better protein adhesion and accelerated osteoblastic differentiation, they could induce quantitatively superior bone regeneration. The study thus seeks to determine whether this technological innovation offers a tangible clinical advantage beyond simple primary osseointegration.

Study design and population

This single-centre, parallel-arm, 12-month clinical trial was conducted according to the SPIRIT guidelines. The study included 25 participants, divided into a test group (TG, n=12) and a control group (CG, n=13), to evaluate the impact of implant surface characteristics on bone regeneration after sinus lift.

Surgical protocol and experimental groups

All patients underwent a transcrestal sinus floor elevation associated with the immediate placement of a single implant. The grafting material used was a collagenated hydroxyapatite (putty-type material). Two types of implant surfaces were compared:

• Test Group (TG): Implants with nanoscale super-hydrophilic surface.
• Control Group (CG): Implants with conventional moderate surface roughness.

Evaluation and statistical analysis

Radiographic follow-up was performed immediately after the procedure and at 12 months postoperatively. The primary evaluation criteria included:

• The change in bone volume (expressed in mm³).
• The maximum bone height gain (expressed in mm).
• Peri-implant crestal bone level.

Les données ont été analysées via un modèle de régression linéaire multivariée afin de déterminer l'influence de la nature de la surface et des variables cliniques sur la variance des résultats observés.

Comparative analysis of bone regeneration at 12 months

The study was completed by 25 participants, divided between the Test group (TG, n=12, implants with super-hydrophilic surface) and the Control group (CG, n=13, implants with moderately rough surface). Radiographic measurements taken immediately after insertion and at 12 months post-operatively reveal notable numerical differences, although the statistical power remains insufficient to conclude a clear superiority.

Evaluated parameter (mean and standard deviation)	Test Group (TG) - Super-hydrophilic	Control Group (CG) - Conventional	p-value
Bone volume change (mm³)	207.41 (SD 168.10)	94.54 (SD 70.24)	0.087
Bone height gain (mm)	5.02 (SD 1.71)	6.25 (SD 1.88)	0.123

Sur le plan volumétrique, le groupe utilisant la surface nanoscale super-hydrophile affiche un gain moyen de 207,41 mm³, soit plus du double de celui observé dans le groupe contrôle (94,54 mm³). Toutefois, en raison d'une forte variabilité interindividuelle (écart-type de 168,10 dans le groupe TG), cette différence ne franchit pas le seuil de significativité statistique (p = 0,087).

Modeling and clinical observations

Data analysis highlights the following points:

• Height gain: Unlike volume, the maximum bone height gain is slightly higher in the control group (6.25 mm versus 5.02 mm for the test group), with no significant difference (p = 0.123).
• Multivariate analysis: Linear regression models constructed to evaluate the impact of surface characteristics and clinical variables only partially explain the observed variance (8.6% for volume and 35.4% for height). The predictions derived from these models are not statistically significant.
• Qualitative evaluation: Radiographic imaging confirms a trend towards better volumetric expansion of the graft (collagenated hydroxyapatite) in contact with hydrophilic surfaces, although the study design does not allow this factor to be isolated as the sole determinant of regenerative success.

In summary, while the super-hydrophilic surface appears to promote greater volumetric filling dynamics, the 12-month clinical results in terms of bone height and peri-implant crestal bone level remain comparable to conventional rough surfaces.

Clinical analysis of results

The results of this single-center clinical trial provide a necessary nuance to the enthusiasm surrounding super-hydrophilic surfaces. Although the test group (super-hydrophilic nanostructure) showed a higher mean volumetric increase (207.41 mm³ versus 94.54 mm³ for the control group), statistical analysis does not allow for a claim of significant superiority (p = 0.087). Surprisingly, the bone height gain was numerically higher in the control group (6.25 mm) than in the test group (5.02 mm), without being statistically significant either (p = 0.123).

Limits and perspective

The main limitation of this study lies in the small sample size (n=25), which limits the statistical power required to validate the observed trend on volume. Furthermore, the multivariate regression model only explains 8.6% to 35.4% of the observed variance, suggesting that other unidentified clinical variables or individual variability play a predominant role in sub-sinus bone regeneration, beyond surface physico-chemistry alone.

Implications for practice

While literature often highlights the acceleration of osseointegration by bioactive surfaces in native bone, this study indicates that their impact on the regenerated volume during crestal sinus floor elevation remains modest. The choice of surface does not appear, at this stage, to be the primary lever for success for this specific protocol using collagenated hydroxyapatite.

Summary of results

This clinical study conducted on 25 participants shows that super-hydrophilic surface implants (TG) achieve a regenerated bone volume of 207.41 mm³ (±168.10) compared to 94.54 mm³ (±70.24) for moderately rough surfaces (CG) at 12 months. Despite this marked volumetric trend, no statistically significant difference was highlighted for volume gain (p = 0.087) nor for bone height gain (5.02 mm for TG vs 6.25 mm for CG; p = 0.123).

In concrete terms, for the practitioner:

• Surface choice: In the case of trans-crestal sinus lift, super-hydrophilicity alone does not guarantee superior bone regeneration compared to conventional moderate roughness implants; do not overvalue this criterion in your immediate decision-making.
• Protocol reliability: The Summers technique with collagenated hydroxyapatite remains a predictable option, offering a stable bone height gain (approximately 5 to 6 mm) regardless of the implant surface condition used.
• Clinical focus: The observed variance suggests that other parameters (sinus anatomy, primary stability) take precedence over implant wettability for the one-year bone outcome.

In the quest for accelerated osseointegration, the wettability of implant surfaces emerges as a major biological lever. This single-center clinical study, conducted over 12 months, evaluated the impact of a new nanometric roughness combined with a super-hydrophilic surface on bone gain after crestal sinus lift. The stakes are high: transforming titanium from a bioinert material into a physiologically active surface capable of optimizing regeneration in quantitatively limited sites. The protocol included 25 patients, divided between a test group (TG, n=12) receiving implants with a nanometric super-hydrophilic surface, and a control group (CG, n=13) with implants featuring conventional moderate roughness. The procedure, standardized according to SPIRIT guidelines, used a collagenated hydroxyapatite graft to fill the sub-sinus space created via the trans-crestal approach. Radiographic results at one year reveal a marked trend, although statistically silent. The test group (TG) showed a mean bone volume change of 207.41 mm³ (SD 168.10), compared to 94.54 mm³ (SD 70.24) for the control group. However, despite this apparent doubling of volume, the p-value stands at 0.087, failing to cross the threshold of significance. Regarding bone height, the CG showed a gain of 6.25 mm versus 5.02 mm for the TG (p = 0.123). This study highlights the complexity of sinus regeneration. While the super-hydrophilic surface seems to favor an overall larger volume, the observed variance and the modest sample size prevent concluding a clear superiority. The multivariate regression model could only explain a small part of the variance (8.6% to 35.4%), suggesting that other clinical variables weigh heavily on the final result. In summary, nanometric innovation shows a positive signal on a volumetric level, but the systematic clinical benefit remains to be confirmed by larger cohorts to overcome statistical 'noise'.

---

Information intended for healthcare professionals. This content may contain errors or truncated summaries. We recommend always verifying with the original source article. Delynov disclaims all responsibility regarding the use of this information. This document is not intended for patients or the general public.