The present study aimed to examine the middle-term effects of transcrestal double-sinus elevation (TSFE) versus alveolar/palatal split expansion technique (APS) and simultaneous implant placement in the augmented sinus. Null hypothesis: there were no differences between groups.

Magnetoelectric device was used for bone augmentation and expansion techniques in long-standing edentulous patients with a deficiency in vertical height in the posterior maxilla (3mm to 4mm residual bone height): TSFE group, or two-stage process with a first transcrestal sinus floor augmentation and a second sinus floor elevation with immediate implant placement; APS group, or “dual split and dislocation” of the two cortical bony plates towards the sinus and palatal side. Volumetric and linear analyses were performed on the superimposed preoperative and postoperative 3-year computed tomography scans. The level of significance was set at 0.05.

Thirty patients were selected for the present analysis. For both groups significant differences were found in the volume outcomes between baseline and 3-year follow-up, showing a gain of about +0.28±0.06cm³ for the TSFE group, and +0.43±0.12cm³ for the APS group, with p-values < 0.0001. However, an effective increase of the volume of the alveolar crest was registered just in the APS group (+0.22±0.09cm³).

A significant increase in bone width was found in the APS group (+1.45±0.56mm with p-value < 0.0001); on the contrary, a slight width reduction of the alveolar crest was observed in the TSFE group (-0.63±0.21mm).

TSFE procedure seemed to not affect the shape of the alveolar crest. APS procedures led to a higher increase of the volume available for dental implant placement and could be used in horizontal bone defects too.