Nanoclay Promotes Mouse Cranial Bone Regeneration Mainly through Modulating Drug Binding and Sustained Release.

Nanoclay (Nanosilicates, NS) is appearing as an intriguing 2D nanomaterial for bone tissue engineering with multiple proposed functions, e.g., intrinsic osteoinductivity, improving mechanical properties, and drug release capacity. However, the mechanism of NS for in vivo bone regeneration has been hardly defined so far. This knowledge gap will significantly affect the design/application of NS-based biomaterials. To determine the role of NS in osteoblastic differentiation and bone formation, we used the mouse calvarial-derived pre-osteoblasts (MC3T3-E1) and a clinically-relevant mouse cranial bone defect model. Instead of a hydrogel, we prepared biomimetic 3D gelatin nanofibrous scaffolds (GF) and NS-blended composite scaffolds (GF/NS) to determine the essential role of NS in critical low-dose (0.5 µg per scaffold) of BMP2-induced cranial bone regeneration. In contrast to "osteoinductivity", our data indicated that NS could enable single-dose of BMP2, promoting significant osteoblastic differentiation while multiple-dose of BMP2 (without NS) was required to achieve similar efficacy. Moreover, our release study revealed that direct binding to NS in GF scaffolds provided stronger protection to BMP2 and sustained release compared to GF/NS composite scaffolds. Consistently, our in vivo data indicated that only BMP2/NS direct binding treatment was able to repair the large mouse cranial bone defects after 6 weeks of transplantation while neither BMP2, NS alone, nor BMP2 released from GF/NS scaffolds was sufficient to induce significant cranial bone defect repair. Therefore, we concluded that direct nanoclay-drug binding enabled sustained release is the most critical contribution to the significantly improved bone regeneration compared to other possible mechanisms based on our study.

Genome-wide DNA methylation investigation of glucocorticoid exposure within buccal samples.

AIM: Glucocorticoids play a major role in regulating the stress response, and an imbalance of glucocorticoids has been implicated in stress-related disorders. Within mouse models, CpGs across the genome have been shown to be differentially methylated in response to glucocorticoid treatment, and using the Infinium 27K array, it was shown that humans given synthetic glucocorticoids had DNA methylation (DNAm) changes in blood. However, further investigation of the extent to which glucocorticoids affect DNAm across a larger proportion of the genome is needed. METHODS: Buccal samples were collected before and after synthetic glucocorticoid treatment in the context of a dental procedure. This included 30 tooth extraction surgery patients who received 10 mg of dexamethasone. Genome-wide DNAm was assessed with the Infinium HumanMethylationEPIC array. RESULTS: Five CpGs showed genome-wide significant DNAm changes that were >10%. These differentially methylated CpGs were in or nearest the following genes: ZNF438, KLHDC10, miR-544 or CRABP1, DPH5, and WDFY2. Using previously published datasets of human blood gene expression changes following dexamethasone exposure, a significant proportion of genes with false-discovery-rate-adjusted significant CpGs were also differentially expressed. A pathway analysis of the genes with false-discovery-rate-adjusted significant CpGs revealed significant enrichment of olfactory transduction, pentose and glucuronate interconversions, ascorbate and aldarate metabolism, and steroid hormone biosynthesis pathways. CONCLUSION: High-dose synthetic glucocorticoid administration in the setting of a dental procedure was significantly associated with DNAm changes within buccal samples. These findings are consistent with prior findings of an influence of glucocorticoids on DNAm in humans.

A Review of Dental Anatomy and Dental Injury Associated With Anesthesia.

Dental injury during airway management is a common complication encountered during the administration of general anesthesia. This article gives an overview of the frequency of dental injuries, dental anatomy, conditions that increase the risk of dental injury, and mechanism of injury, as well as discusses injury management and avoidance of dental trauma. Although this article does not encompass all situations and variables, it covers these topics in a useful and easily remembered manner that the anesthetist can easily incorporate into practice.

Maxillomandibular Fixation and Anesthesia Management.

Maxillomandibular fixation (MMF) is a frequent issue encountered during the administration of general anesthesia. This article aims to give an overview of MMF from a surgical perspective, complications that can arise from MMF, anesthesia management strategies in MMF cases, and perhaps most importantly, an overview of how to release a patient from MMF in an emergency. Although not encompassing all situations and variables, these topics are covered in a manner that can be easily incorporated into the anesthetist's practice.

Use of Intraoperative Navigation for Minimally Invasive Retrieval of a Broken Dental Needle.

This report describes a case of needle breakage during an inferior alveolar nerve block to perform a restorative dental procedure on a 13-year-old patient. The needle was removed in a minimally invasive fashion using a Medtronic StealthStation S7 surgical navigation system and custom interocclusal splint to allow for stable, identically repeatable positioning of the mandible. This report adds another example of the utility of image-guided surgery for the removal of foreign bodies from the head and neck region in a minimally invasive fashion.