Repairing bone defects in oral surgery often requires the use of bone regeneration techniques. Silicon is an element that has been employed as regeneration material in several studies. In our study, silicon was combined with autologous bone and platelet-rich fibrin (PRF) membranes to analyse the behaviour of this element in bone regeneration. Four circumferential defects were created in the cranial vault of five New Zealand rabbits. The following elements were applied to the regeneration of the defects: (P): PRF; (S): silicon and (B): autologous bone, with the following distribution of study groups: Group 1 (PSB); Group 2 (PS); Group 3 (SB) and Group 4 (CONTROL): unregenerate group. The animals were sacrificed after 3 weeks. Computed microtomography studies (μ-CT) were carried out, as well as histomorphometric ones. The ANOVA statistical test was used with a Bonferroni post-hoc test to compare the results (p ≤ 0.05). Radiologically, groups PSB and SB were better as far as quantity and percentage of healthy bone observed, but not significantly compared to the control group. The PS group was significantly worse. The histological test revealed that the PSB group was the one to present the largest area, percentage and perimeter of mineralised bone. On evaluating the forming bone (osteoid), no difference was observed across the groups with the exception of the bone perimeter, where the SB group was significantly better. The bone height variable showed no significant differences. In conclusion we can state that the combination of PRF, autologous bone and silicon provides good results at 3 weeks whilst the PS group shows the worst results. This highlights the importance of autologous bone forming part of the graft material in order for the bone to mineralise.

Recently, some clinicians have proposed implanting polydioxanone (PDO) threads imbibed in hyaluronic acid (HA), arguing that this may reinforce the lifting effects. However, this is controversial because PDO sutures are hydrophilic and the presence of HA could increase the rate of hydrolysis. The aim of this study was to demonstrate the degradation of PDO lifting threads in HA through ultramicroscopy. It was a qualitative research and preclinical trial. Three, 1-cm-long, segments of 23-G PDO threads were immersed in 1.5-mL non-crosslinked HA in previously labeled, sterile microcentrifuge tubes. These were observed by ultramicroscopy at 4× and 10× after 24, 48, and 72 h. Microphotographs taken after 24 h show structural changes in the fibers, presenting an increase in interlaminar spaces and dilution of violet pigmentation. At 48 h, degradation continues. PDO hygroscopy is observed as aqueous content between the peripheral layers and the central core of the thread. At 72 h, as the pigment is released, larger empty spaces are observed in the central column of the thread, and there is disorganization of the peripheral fibrils with fraying all along the fiber. HA induces rapid biodegradation of the PDO thread by hydrolysis beginning 24 h after contact of the thread with the biomaterial. The non-crosslinked HA is a powerful catalyzing agent for hydrolytic degradation of the PDO thread, because this thread is highly hydrophilic. Clinically, embedding PDO threads in HA accelerates biodegradation of the suture.

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