Bone Regeneration After Sinus Floor Elevation in an Intact Sinus or a Sinus With Prior Large Membrane Perforation: A Preclinical Study Using a Rabbit Sinus Model

AIM To determine bone regeneration following sinus floor elevation (SFE) at sites with or without prior sinus membrane perforation. MATERIALS AND METHODS The sinus membranes in the maxillary sinuses of 12 rabbits were intentionally perforated (≥ 5 mm) on one side, followed by application of a collagen matrix. SFE was performed on both sinuses after 8 weeks of healing, presenting two groups: SFE with a previous large sinus membrane perforation (group SFE_Perf), and in an intact sinus (group SFE). The animals were euthanized at 2 and 4 weeks after SFE. Micro-computed tomographic and histomorphometric analyses were performed. RESULTS The amount of newly formed bone within the augmented area did not differ significantly between the two groups at 2 weeks and 4 weeks (4.7 ± 1.0 mm$^{2}$ vs. 5.3 ± 1.4 mm$^{2}$ and 9.2 ± 1.7 mm$^{2}$ vs. 10.8 ± 2.2 mm$^{2}$, respectively, mean ± SD; p > 0.05). However, the amount of newly formed bone near the middle of the sinus membranes was significantly greater in group SFE than in group SFE_Perf (p < 0.05). There was no significant difference in the augmented volume. Fewer subepithelial glands and denser collagen fibres within the sinus membranes were observed in group SFE_Perf than in group SFE. CONCLUSIONS A large perforation of the sinus membrane followed by an 8-week healing period did not jeopardize new bone formation following SFE.