Revascularization and angiogenesis for bone bioengineering in the craniofacial region: a review.

The revascularization of grafted tissues is a complicated and non-straightforward process, which makes it challenging to perform reconstructive surgery for critical-sized bone defects. This challenge is combined with the low vascularity that results from radiotherapy. This low vascularity could result from ischemia-reperfusion injuries, also known as ischemia which may happen upon grafting. Ischemia may affect the hard tissue during reconstruction, and this can often cause resorption, infections, disfigurement, and malunion. This paper therefore reviews the clinical and experimental application of procedures that were employed to improve the reconstructive surgery process, which would ensure that the vascularity of the tissue is maintained or enhanced. It also presents the key strategies that are implemented to perform tissue engineering within the grafted sites aiming to optimize the microenvironment and to enhance the overall process of neovascularization and angiogenesis. This review reveals that the current strategies, according to the literature, are the seeding of the mature and progenitor cells, use of extracellular matrix (ECM), co-culturing of osteoblasts with the ECM, growth factors and the use of microcapillaries incorporated into the scaffold design. However, due to the unstable and regression-prone capillary structures in bone constructs, further research focusing on creating long-lasting and stable blood vessels is required.

Effect of hypothyrodism's medication (T4) on implant osstointegration: A case series and literature search.

INTRODUCTION: Hypothyroidism reduces the recruitment, maturation, and activity of bone cells, decreasing bone resorption and formation. Several investigations have reported that T4 replacement therapy is associated with a significant decrease in bone mineral density in various skeletal parts, while others have failed to corroborate these results. The present study describes both a literature review and our own experience with dental implants in patients with hypothyroidism undergoing T4 replacement therapy. CASE PRESENTATION: The study included two parts: a literature review and case series. The literature review included 12 articles documenting the success rate of osseointegrated dental implants in patients with hypothyroidism. The clinical cases were chosen from King Saud University Dental College, Riyadh. The patients' identity was only available to the main researcher. The inclusion criteria for the clinical cases were: T4-treated hypothyroidism, age 20-60 years, and use of dental implants with a follow-up period of 6-12 months after loading. The exclusion criteria were: any other medical condition alongside hypothyroidism, syndromic hypothyroidism, pregnancy, current smoking, bruxism, and hypothyroidism caused by surgical excision combined with radiotherapy. The following parameters were assessed: insertion torque (IT), crestal bone height (CBH), mesial bone width (MBW), and distal bone width (DBW) at different time points, probing depth, and signs of infection. DISCUSSION: Seventeen dental implants placed in patients with T4-treated hypothyroidism showed median IT success (42.4 N⋅cm; range: 35-45 N⋅cm). The median crestal bone loss was measured at 6-12 months after loading was 0.6 mm (range: 0.5-0.7. mm). Conversely, the median bone loss differences in MBW and DBW at 6-12 months after loading were 0.3 mm and 0.2 mm, respectively. CONCLUSION: After a 1-year follow-up, patients with T4-treated hypothyroidism who had received dental implants fulfilled the criteria for successful implants.

The use of muscle extracellular matrix (MEM) and SCPC bioceramic for bone augmentation.

BACKGROUND: Bone augmentation is a challenging problem in the field of maxillofacial surgery. OBJECTIVE: In this study, we prepared and evaluated muscle extracellular matrix (MEM) after adding silica calcium phosphate composite (SCPC) seeded with human bone marrow mesenchymal cells (hBMSCs). We then investigated bone augmentation in vivo using the prepared MEM-SCPC. MATERIALS AND METHODS: hBMSCs were seeded on MEM-SCPC, and MEM was characterized. Calvarial bone grafts were prepared using nude mice (n = 12) and grafted separately in two experimental groups: grafts with MEM (control, n = 4) and grafts with MEM-SCPC-hBMSCs (experimental group, n = 8) for 8 weeks. Micro-computed tomography (micro-CT) and histological analysis were then performed. RESULTS: Micro-CT analysis demonstrated a thinner trabeculae in grafted defects than normal native bone, with a high degree of anisotropy. Quantitative histomorphometric assessment showed a higher median bone percentage surface area of 80.2% ± 6.0% in the experimental group. CONCLUSION: The enhanced bone formation and maturation of bone grafted with MEM-SCPC-hBMSCs suggested the potential use of this material for bone augmentation.

Characterization of osteogenic cells grown over modified graphene-oxide-biostable polymers.

Graphene is an excellent filler for the development of reinforced composites. This study evaluated bone cement composites of graphene oxide (GO) and poly(methyl methacrylate) (PMMA) based on the proliferation of human bone marrow mesenchymal stem cells (hBMSCs), and the anabolic and catabolic effects of the incorporation of GO on osteoblast cells at a genetic level. Surface wettability and roughness were also evaluated at different GO concentrations (GO1: 0.024 wt% and GO2: 0.048 wt%) in the polymer matrix. Fabricated specimens were tested to (a) observe cell proliferation and (b) identify the effectiveness of GO on the expression of bone morphogenic proteins. Early osteogenesis was observed based on the activity of alkaline phosphatase and the genetic expression of the run-related transcription factor 2. Moreover, bone strengthening was determined by examining the collagen type 1 alpha-1 gene. The surface roughness of the substrate material increased following the addition of GO fillers to the resin matrix. It was found that over a period of ten days, the proliferation of hBMSCs on GO2 was significantly higher compared to the control and GO1. Additionally, quantitative colorimetric mineralization of the extracellular matrix revealed greater calcium phosphate deposition by osteoblasts in GO2. Furthermore, alizarin red staining analysis at day 14 identified the presence of mineralization in the form of dark pigmentation in the central region of GO2. The modified GO-PMMA composite seems to be promising as a bone cement type for the enhancement of the biological activity of bone tissue.

Assessment of the referral system for surgical removal of third molars at the Dental Faculty, King Saud University.

INTRODUCTION: There is compelling evidence that prophylactic extraction of third molars is a health problem that needs to be addressed. In particular, the vast amount of evidence demonstrating complications after removal of third molars, rather than supporting the necessity of removal or the negative effects of retention, raise this concern. OBJECTIVE: The aim of this study was to investigate the referral system for third molar extraction at our institution by assessing patient opinions and the experience of the oral surgeons and the referring dentists. The main outcome measures of concern were the reasons for third molar extraction, patient awareness about the surgery and the comorbidities that may accompany the surgery. METHODS: Pilot cross-sectional survey questionnaires were distributed at the Dental Faculty Clinic at King Saud University, from 15 March 2015 to 30 June 2016 by the staff in charge of the patient waiting area, oral surgery clinic, primary care clinic and specialist clinic. RESULTS: Of 400 potential respondents, 226 completed the survey (response rate: 54%). Of these patients, 91% knew why they had been referred to the oral surgery department, but 73.5% did not understand the surgical extraction procedure or its complications. In total, 45.2% of the patients referred had no signs or symptoms, and 36% were referred for prophylactic reasons. In conclusion, our system needs reassessment. To combat the subjective health practice of routinely referring patients for prophylactic extraction, the role of primary care should be emphasised by implementing a system for regular patient check-ups, and public awareness should be increased.