Complications Following Alloplastic Chin Augmentation: A Systematic Review of Implant Materials and Surgical Techniques
BACKGROUND:Alloplastic implantation has become a popular method of chin augmentation. Historically, silicone was the most commonly used implant, but porous materials have grown in favor due to improved fibrovascularization and stability. Nevertheless, it is unclear which implant type has the most favorable complication profile. This systematic review aims to compare the complications of published chin implants and surgical approaches to provide data-driven recommendations for optimizing chin augmentation outcomes. METHODS:The PubMed® database was queried on March 14, 2021. We selected studies reporting data on alloplastic chin augmentation excluding additional procedures such as osseous genioplasty, fat grafting, autologous grafting, and fillers. The following complications were extracted from each article: malposition, infection, extrusion, revision, removal, paresthesias, and asymmetry. RESULTS:Among the 39 articles analyzed, the year of publication ranged from 1982 to 2020; additionally, 31 were retrospective case series, 5 were retrospective cohort or comparative studies, 2 were case reports, and 1 was a prospective case series. More than 3104 patients were included. Among the 11 implants reported, the 3 implants with the highest number of publications were silicone, high-density porous polyethylene (HDPE), and expanded polytetrafluoroethylene (ePTFE). Silicone demonstrated the lowest rates of paresthesias (0.4%) compared to HDPE (20.1%, P < 0.01) and ePTFE (3.2%, P < 0.05). In contrast, there were no statistically significant differences in rates of implant malposition, infection, extrusion, revision, removal, or asymmetry when stratified by implant type. Various surgical approaches were also documented. Compared with subperiosteal implant placement, the dual-plane technique demonstrated higher rates of implant malposition (2.8% vs 0.5%, P < 0.04), revision (4.7% vs 1.0%, P < 0.001), and removal (4.7% vs 1.1%, P < 0.01), but a lower incidence of paresthesias (1.9% vs. 10.8%, P < 0.01). Compared with extraoral incisions, intraoral incisions resulted in higher rates of implant removal (1.5% vs 0.5%, P < 0.05) but lower rates of asymmetry (0.7% vs 7.5%, P < 0.01). CONCLUSION:Silicone, HDPE, and ePTFE had low overall complication rates, demonstrating an acceptable safety profile regardless of implant selection. Surgical approach was found to significantly influence complications. Additional comparative studies on surgical approach while controlling for implant type would be beneficial for optimizing alloplastic chin augmentation practices.
Topical prolyl hydroxylase domain-2 silencing improves diabetic murine wound closure
Prolyl hydroxylase domain 2 (PHD2) has been implicated in several pathways of cell signaling, most notably in its regulation of hypoxia-inducible factor (HIF)-1alpha stability. In normoxia, PHD2 hydroxylates proline residues on HIF-1alpha, rendering it inactive. However, in hypoxia, PHD2 is inactive, HIF-1alpha is stabilized and downstream effectors such as vascular endothelial growth factor and fibroblast growth factor-2 are produced to promote angiogenesis. In the present study we utilize RNA interference to PHD2 to promote therapeutic angiogenesis in a diabetic wound model, presumably by the stabilization of HIF-1alpha. Stented wounds were created on the dorsum of diabetic Lepr db/db mice. Mice were treated with PHD2 small interfering RNA (siRNA) or nonsense siRNA. Wounds were measured photometrically on days 0-28. Wounds were harvested for histology, protein, and RNA analysis. Diabetic wounds treated with siRNA closed within 21+/-1.2 days; sham-treated closed in 28+/-1.5 days. By day 7, Western blot revealed near complete suppression of PHD protein and corresponding increased HIF-1alpha. Angiogenic mediators vascular endothelial growth factor and fibroblast growth factor-2 were elevated, corresponding to increased CD31 staining in the treated groups. siRNA-mediated silencing of PHD2 increases HIF-1alpha and several mediators of angiogenesis. This corresponded to improved time to closure in diabetic wounds compared with sham-treated wounds. These findings suggest that impaired wound healing in diabetes can be ameliorated with therapeutic angiogenesis