Cathepsin-K inhibition enhances anti-cancerous activity within oral squamous cell carcinoma cells: Uncloaking the potency of new K21 formulation

BACKGROUND

The ability of cancer cells to be invasive and metastasize depend on several factors, of which the action of protease activity takes center stage in disease progression.

PURPOSE/OBJECTIVE

To analyze function of new K21 molecule in the invasive process of oral squamous cell carcinoma (OSCC) cell line.

MATERIALS & METHODS

The Fusobacterium (ATCC 23726) streaks were made, and pellets were resuspended in Cal27 (ATCC CRL-2095) OSCC cell line spheroid cell microplate. Cells were seeded and Lysotracker staining performed for CathepsinK red channel. Cell and morphology were evaluated using Transmission Electron microscopy. Thiobarbituric acid assay was performed. OSCC was analyzed for Mic60. Raman spectra were collected from the cancer cell line. L929 dermal fibroblast cells were used for Scratch Assay. ELISA muti arrays were used for cytokines and matrix molecules. Internalization ability of fibroblast cells were also analyzed. Structure of K21 as a surfactant molecule with best docked poses were presented.

RESULTS

Decrease in lysosomal staining was observed after 15 and 30 min of 0.1% treatment. Tumor clusters were associated with cell membrane destruction in K21 primed cells. There was functional silencing of Mic60 via K21, especially with 1% concentration with reduced cell migration and invasiveness. Raman intensity differences were seen at 700 cm^-1, 1200 cm^-1 and 1600 cm^-1 regions. EVs were detected within presence of fibroblast cells amongst K21 groups. Wound area and wound closure showed the progress of wound healing.

CONCLUSION

Over expression of CatK can be reduced by a newly developed targeted K21 based drug delivery system leading to reduced migration and adhesion of oral squamous cell carcinoma cells. The K21 drug formulation can have great potential for cancer therapies due to targeting and cytotoxicity effects.

Effects of Riboflavin Collagen Crosslinker on Dentin Adhesive Bonding Efficiency: A Systematic Review and Meta-Analysis

The aim of this study was to evaluate published data regarding riboflavin (RF) as a cross-linker for improved adhesive bond strength to dentin and to analyze previous studies for optimal concentration of riboflavin range suitable for dentin bond. Saliva and distilled water were used as storage media and aging time was 24 h and 6 months. Results of meta-analysis were synthesized using a statistical method of inverse variance in random effects with a 95% Confidence Interval (CI). Cochrane review manager 5.4.1 was used to determine results of the meta-analysis. In total, 3172 articles were found from search databases "PubMed", "Scopus", and "Google Scholar". Six of the fifteen studies were eligible for meta-analysis. Micro tensile strength shows significant improvement with the addition of riboflavin (p < 0.05) compared to without the addition of riboflavin from with 95% CI. A significant difference has been found in micro tensile bond strength between use of the riboflavin cross-linker and without use of the riboflavin crosslinker in the dentin adhesive system. With a 95% confidence interval (CI), the I² for micro tensile strength was 89% with strong heterogeneity, Chi² = 44.76, df = 5 (p < 0.00001), and overall effect size is Z = 2.22 (p = 0.03) after immediate aging. Chiang et al. 2013 shows maximum mean differences which is 38.50 [17.93-59.07]. After 6 months of aging in distilled water or artificial saliva micro tensile bond strength has been increased with the addition of riboflavin (p < 0.05). It can be clearly seen that pooled effect and 95% CI did not cross the line of no effect. With a 95% confidence interval (CI), the I² for micro tensile strength was 96% with strong heterogeneity, Chi² = 117.56, df = 5 (p < 0.00001), and overall effect size is Z = 2.30 (p = 0.02). Subgroup analysis proved a similar effect of distilled water and artificial saliva as storage media on micro tensile bond strength after incorporating riboflavin as a collagen crosslinker. An artificial saliva aged forest plot also showed considerable heterogeneity with I² = 96%; Tau² = 257.32; Chi² = 94.37; df = 2 (p < 0.00001); test for overall effect, Z = 1.06 (p = 0.29). Riboflavin prior to or with bonding is recommended to improve the bonding of different adhesive systems.

Vacuum cleaner friction injuries in paediatrics: A 10 year review of national trends

Our regional burns service has gained experience in managing paediatric hand friction burns due to vacuum cleaners (VC). We aimed to evaluate our 10 year experience managing these injuries as well as reviewing national data trends in order to identify those at risk of injury.

MATERIALS AND METHODS

A International Burns Injury Database (IBID) request was made to review the number of burn injuries recorded due to Vacuum cleaner injuries (VCIs). In addition, a local IBID request was made to identify the number of burn injuries managed within our regional burns service.

RESULTS

We identified 288 VCIs which have increasingly occurred in England and Wales between 1996-2020 and 32 children who sustained these injuries within our regional burns service. A general theme from both national and local data highlighted that these injuries occurred in males (78%, n=25) with a mean age of 20 months (9 months-4.5 years) affecting children's hands (94%). In 25 cases (78%) these injuries involved an interphalangeal joint. 85% (n = 27) of injuries were deep dermal/full thickness with eleven children (34%) undergoing surgical excision and skin grafts.

DISCUSSION

Significant paediatric burn injuries can be sustained from VCs. Greater awareness is indicated for these injuries and legislation should be considered in order to improve the safety of vacuum cleaners. International burn societies are urged to collect data of these injuries in order to co-ordinate improved prevention strategies and change within the VC industry.

Introducing day case thyroid lobectomy at a tertiary head and neck centre

BACKGROUND

Thyroid lobectomy is considered to be a safe day case procedure by the British Association of Day Surgery. However, currently only 5.5% of thyroid surgeries in the UK are undertaken as day cases. We determine if and how thyroid lobectomy with same-day discharge could safely be introduced in our centre.

METHODS

We analysed all thyroid lobectomy surgeries performed between April 2015 and May 2019. Exclusion criteria included completion surgery, revision surgery, additional procedures and disseminated disease. Outcomes were benchmarked against surgeon-reported complications from the British Association of Endocrine and Thyroid Surgery's 5^th National Audit. Additionally, we reviewed the number of patients who met day case criteria currently in use at our hospital to determine accessibility to the service.

RESULTS

In total, 259 thyroid lobectomy surgeries were undertaken and of these 173 met the inclusion criteria. There was no mortality, return to theatre for evacuation of postoperative haematoma or readmission. There was one postoperative haematoma which was drained at the bedside. Some 47 of the 173 (27.2%) patients met day case criteria currently in use at our centre.

CONCLUSIONS

Day case surgery provides a cost-effective solution to rising bed pressures and a coherent protocol can optimise patient safety and experience.

Use of endoscope in teaching of otolaryngology residents about site and size of tympanic membrane perforation and its impact on degree of hearing loss in adult patients: A cross sectional study

OBJECTIVE

To determine the association between site and size of perforation of the tympanic membrane and the level of conductive hearing.

METHODS

The cross-sectional study was conducted from November 2015 to October 2016 at Aga Khan University Hospital Karachi and comprised patients with tympanic membrane perforation without any other middle-ear disease. Karl-Storz Rigid Endoscope attached to a camera was used to take pictures of the tympanic membrane. Site of the perforation was determined using a vertical line to divide the membrane into two anterior and posterior halves. Size of the perforation was calculated as a percentage of the total membrane using Image J software. Data analysis was done using Stata 12.

RESULTS

Of the 55 patients, 29(53%) were males and 26(47%) were females. The overall mean age was 33+/-15 years. With every 5% increase in the size of perforation, the hearing loss increased by 1 decibel. A difference of 5.5 decibels was noted between anterior and posterior perforations of similar size.

CONCLUSION

Hearing loss increased with increase in the size of perforation.

Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

Improved bone regeneration using bone anabolic drug conjugates (C3 and C6) with deproteinized bovine bone mineral as a carrier in rat mandibular defects

BACKGROUND

Deproteinized bovine bone mineral (DBBM) has been extensively studied and used for bone regeneration in oral and maxillofacial surgery. However, it lacks an osteoinductive ability. We developed two novel bone anabolic conjugated drugs, known as C3 and C6, of an inactive bisphosphonate and a bone activating synthetic prostaglandin agonist. The aim was to investigate whether these drugs prebound to DBBM granules have the potential to achieve rapid and enhanced bone regeneration.

METHODS

Bilateral defects (4.3 mm diameter circular through and through) were created in mandibular angles of 24 Sprague-Dawley rats were filled with DBBM Control, DBBM with C3 or DBBM with C6 (n = 8 defects per group/ each timepoint). After 2 and 4 weeks, postmortem samples were analyzed by microcomputed tomography followed by backscattering electron microscopy and histology.

RESULTS

DBBM grafts containing the C3 and C6 conjugated drugs showed significantly more bone formation than DBBM control at 2 and 4 weeks. The C6 containing DBBM demonstrated the highest percentage of new bone formation at 4 weeks. There was no significant difference in the percentage of the remaining graft between the different groups at 2 or 4 weeks.

CONCLUSIONS

DBBM granules containing conjugated drugs C3 and C6 induced greater new bone volume generated and increased the bone formation rate more than the DBBM controls. This is expected to allow the development of clinical treatments that provide more predictable and improved bone regeneration for bone defect repair in oral and maxillofacial surgery.

Achieving enhanced bone regeneration using monetite granules with bone anabolic drug conjugates (C3 and C6) in rat mandibular defects

Bone grafting procedures are commonly used to manage bone defects in the craniofacial region. Monetite is an excellent biomaterial option for bone grafting, however, it is limited by lack of osteoinduction. Several molecules can be incorporated within the monetite matrix to promote bone regeneration. The aim was to investigate whether incorporating bone forming drug conjugates (C3 and C6) within monetite can improve their ability to regenerate bone in bone defects. Bilateral bone defects were created in the mandible of 24 Sprague-Dawley rats and were then packed with monetite control, monetite+C3 or monetite+C6. After 2 and 4 weeks, post-mortem samples were analyzed using microcomputed tomography, histology and back-scattered electron microscopy to calculate the percentages of bone formation and remaining graft material. At 2 and 4 weeks, monetite with C3 and C6 demonstrated higher bone formation than monetite control, while monetite+C6 had the highest bone formation percentage at 4 weeks. There were no significant differences in the remaining graft material between the groups at 2 or 4 weeks. Incorporating these anabolic drug conjugates within the degradable matrix of monetite present a promising bone graft alternative for bone regeneration and repair in orthopedic as well as oral and maxillofacial applications.

In Vivo Bone Effects of a Novel Bisphosphonate-EP4a Conjugate Drug (C3) for Reversing Osteoporotic Bone Loss in an Ovariectomized Rat Model

Pathological bone loss is a regular feature of postmenopausal osteoporosis, and the microstructural changes along with the bone loss make the individual prone to getting hip, spine, and wrist fractures. We have developed a new conjugate drug named C3, which has a synthetic, stable EP4 agonist (EP4a) covalently linked to an inactive alendronate (ALN) that binds to bone and allows physiological remodeling. After losing bone for 12 weeks, seven groups of rats were treated for 8 weeks via tail‐vein injection. The groups were: C3 conjugate at low and high doses, vehicle‐treated ovariectomy (OVX) and sham, C1 (a similar conjugate, but with active ALN at high dose), inactive ALN alone, and a mixture of unconjugated ALN and EP4a to evaluate the conjugation effects. Bone turnover was determined by dynamic and static histomorphometry; μCT was employed to determine bone microarchitecture; and bone mechanical properties were evaluated via biomechanical testing. Treatment with C3 significantly increased trabecular bone volume and vertebral BMD versus OVX controls. There was also significant improvement in the vertebral load‐bearing abilities and stimulation of bone formation in femurs after C3 treatment. This preclinical research revealed that C3 resulted in significant anabolic effects on trabecular bone, and EP4a and ALN conjugation components are vital to conjugate anabolic efficacy. A combined therapy using an EP4 selective agonist anabolic agent linked to an inactive ALN is presented here that produces significant anabolic effects, allows bone remodeling, and has the potential for treating postmenopausal osteoporosis or other diseases where bone strengthening would be beneficial. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Complications in implant dentistry

After tooth loss, an individual may seek tooth replacement so that his/her function and esthetics could be restored. Clinical prosthodontics, during the past decade, has significantly improved and developed according to the advancements in the science and patient's demands and needs. Conventional options in prosthodontics for substituting a missing single tooth include the removable partial denture, partial and full coverage bridgework, and resin-bonded bridgework. Dental implants have gained increasing popularity over the years as they are capable of restoring the function to near normal in both partial and completely edentulous arches. With substantial evidence available, fixed implant-supported prosthesis are fully acknowledged as a reliable treatment option for the replacement of single or multiple missing teeth nowadays. While dental implants are increasingly becoming the choice of replacement for missing teeth, the impediments associated with them are progressively emerging too.

Advancements in all-ceramics for dental restorations and their effect on the wear of opposing dentition

Tooth wear is a process that is usually a result of tooth to tooth and/or tooth and restoration contact. The process of wear essentially becomes accelerated by the introduction of restorations inside the oral cavity, especially in case of opposing ceramic restorations. The newest materials have vastly contributed toward the interest in esthetic dental restorations and have been extensively studied in laboratories. However, despite the recent technological advancements, there has not been a valid in vivo method of evaluation involving clinical wear caused due to ceramics upon restored teeth and natural dentition. The aim of this paper is to review the latest advancements in all-ceramic materials, and their effect on the wear of opposing dentition. The descriptive review has been written after a thorough MEDLINE/PubMed search by the authors. It is imperative that clinicians are aware of recent advancements and that they should always consider the type of ceramic restorative materials used to maintain a stable occlusal relation. The ceramic restorations should be adequately finished and polished after the chair-side adjustment process of occlusal surfaces.

A Novel Anabolic Conjugate (C3) in the Matrix of Dicalcium Phosphate Onlay Block Grafts for Achieving Vertical Bone Augmentation: An Experimental Study on Rabbit Calvaria

PURPOSE

Achieving successful and predictable alveolar ridge augmentation in the vertical dimension is extremely challenging. Several materials have been investigated to achieve vertical ridge augmentation; however, the results are highly unpredictable. The collaborative team presenting this research has developed brushite- and monetite-based grafts that incorporate in their matrix a novel bone anabolic conjugate (C3) of a bisphosphonate and a potent bone-activating EP4 receptor agonist. The study objective was to investigate the potential of these graft formulations to achieve rapid, enhanced, and clinically significant bone regeneration in the vertical dimension.

MATERIALS AND METHODS

Brushite and monetite grafts were fabricated and characterized for phase purity, porosity, compressive strength, and microstructural morphology. They were implanted in 12 rabbit calvaria for 12 weeks. Each group (n = 6): brushite control, brushite with C3, monetite control, and monetite with C3. Postmortem samples were retrieved and processed for analysis. The percentage bone volume, vertical bone height gained, and graft resorption were calculated and assessed.

RESULTS

The brushite and monetite grafts containing C3 integrated well onto the calvarial bone surface, with new bone extending through the graft area (36% and 80%, respectively), while the C3 lacking grafts showed decreased surface integration and bone infiltration (28% and 38%, respectively). The C3 containing brushite and monetite grafts demonstrated bone growth vertically (1.8 mm and 2.7 mm, respectively) and improved graft resorption.

CONCLUSION

The brushite- and monetite-based grafts loaded with the C3 conjugate resulted in greater de novo bone formation in the vertical dimension when compared with the grafts without the drug. However, the monetite grafts produced much more and predictable vertical height gain than was achieved with brushite grafts. The advantages of this new graft drug formulation in future would be to provide more predictable vertical bone regeneration, which will ultimately benefit patients undergoing dental implant placement.

Resolving Macrophages Counter Osteolysis by Anabolic Actions on Bone Cells

Progression of inflammatory osteolytic diseases, including rheumatoid arthritis and periodontitis, is characterized by increased production of proinflammatory mediators and matrix-degrading enzymes by macrophages and increased osteoclastic activity. Phenotypic changes in macrophages are central to the healing process in virtually all tissues. Using a murine model of periodontitis, we assessed the timing of macrophage phenotypic changes and the impact of proresolving activation during inflammatory osteolysis and healing. Proinflammatory macrophage activation and TNF-α overproduction within 3 wk after induction of periodontitis was associated with progressing bone loss. Proresolving activation within 1 wk of stimulus removal and markers of resolving macrophages (IL-10, TGF-β, and CD206) correlated strongly with bone levels. In vivo macrophage depletion with clodronate liposomes prevented bone resorption but impaired regeneration. Induction of resolving macrophages with rosiglitazone, a PPAR-γ agonist, led to reduced bone resorption during inflammatory stimulation and increased bone formation during healing. In vitro assessment of primary bone marrow-derived macrophages activated with either IFN-γ and LPS (proinflammatory activation) or IL-4 (proresolving activation) showed that IL-4-activated cells have enhanced resolving functions (production of anti-inflammatory cytokines; migration and phagocytosis of aged neutrophils) and exert direct anabolic actions on bone cells. Cystatin C secreted by resolving but not inflammatory macrophages explained, in part, the macrophage actions on osteoblasts and osteoclasts. This study supports the concept that therapeutic induction of proresolving functions in macrophages can recouple bone resorption and formation in inflammatory osteolytic diseases.

Comparative adsorption profiles of basal lamina proteome and gingival cells onto dental and titanium surfaces

Titanium (Ti) dental implants are susceptible to bacterial infections and failure due to lack of proper epithelial seal. Epithelial cells establish a strong epithelial seal around natural teeth by the deposition of basal lamina (BL) proteins that adsorb on the tooth surface. This seal can even be re-established onto cementum or dentin following injury or periodontal therapy. However, it is unclear how tooth surfaces promote this cell attachment and protein adsorption. Understanding the interactions between BL proteins and epithelial cells with dentin and Ti will facilitate the development of implant surfaces that promote the formation of an epithelial seal and improve the success of periodontal therapy and wound healing on natural teeth. To study these interactions, we used a surface proteomic approach to decipher the adsorption profile of BL proteins onto Ti and dentin, and correlated these adsorption profiles with in vitro interactions of human gingival fibroblasts and epithelial cells. Results showed that dentin adsorbed higher amounts of key BL proteins, particularly laminin and nidogen-1, and promoted more favorable interactions with epithelial cells than Ti. Next, dentin specimens were deproteinized or partially demineralized to determine if its mineral or protein component was responsible for BL adsorption and cell attachment. Deproteinized (mineral-rich) and partially demineralized (protein-rich) dentin specimens revealed BL proteins (i.e. laminin and nidogen-1) and epithelial cells interact preferentially with dentinal proteins rather than dentin mineral. These findings suggest that, unlike Ti, dentin and, in particular, dentinal proteins have a selective affinity to BL proteins that enhance epithelial cell attachment.

STATEMENT OF SIGNIFICANCE

It is remains unclear why natural teeth, unlike titanium dental implants, promote the formation of an epithelial seal that protects them against the external environment. This study used a surface screening approach to analyze the adsorption of proteins produced by epithelial tissues onto tooth-dentin and titanium surfaces, and correlate it with the behaviour of cells. This study shows that tooth-dentin, in particular its proteins, has a higher selective affinity to certain adhesion proteins, and subsequently allows more favourable interactions with epithelial cells than titanium. This knowledge could help in developing new approaches for re-establishing and maintaining the epithelial seal around teeth, and could pave the way for developing implants with surfaces that allow the formation of a true epithelial seal.

Natural graft tissues and synthetic biomaterials for periodontal and alveolar bone reconstructive applications: a review

Periodontal disease is categorized by the destruction of periodontal tissues. Over the years, there have been several clinical techniques and material options that been investigated for periodontal defect repair/regeneration. The development of improved biomaterials for periodontal tissue engineering has significantly improved the available treatment options and their clinical results. Bone replacement graft materials, barrier membranes, various growth factors and combination of these have been used. The available bone tissue replacement materials commonly used include autografts, allografts, xenografts and alloplasts. These graft materials mostly function as osteogenic, osteoinductive and/or osteoconductive scaffolds. Polymers (natural and synthetic) are more widely used as a barrier material in guided tissue regeneration (GTR) and guided bone regeneration (GBR) applications. They work on the principle of epithelial cell exclusion to allow periodontal ligament and alveolar bone cells to repopulate the defect before the normally faster epithelial cells. However, in an attempt to overcome complications related to the epithelial down-growth and/or collapse of the non-rigid barrier membrane and to maintain space, clinicians commonly use a combination of membranes with hard tissue grafts. This article aims to review various available natural tissues and biomaterial based bone replacement graft and membrane options used in periodontal regeneration applications.

Effect of processing conditions of dicalcium phosphate cements on graft resorption and bone formation

Dicalcium phosphate cements (brushite and monetite) are resorbable biomaterials with osteoconductive potential for bone repair and regeneration that have yet to gain widespread commercial use. Brushite can be converted to monetite by heat treatments additionally resulting in various changes in the physico-chemical properties. However, since conversion is most commonly performed using autoclave sterilisation (wet heating), it is uncertain whether the properties observed for monetite as a result of heating brushite under dry conditions affect resorption and bone formation favourably. This study was designed to produce monetite grafts of differing physical form by autoclaving and dry heating (under vacuum) to be compared with brushite biomaterials in an orthotopic pre-clinical implantation model in rabbit for 12weeks. It was observed that monetite grafts had higher porosity and specific surface area than their brushite precursors. The autoclaved monetite grafts had compressive strength reduced by 50% when compared with their brushite precursors. However, the dry heat converted monetite grafts had compressive strength comparable with brushite. Results from in vivo experiments revealed that both types of monetite graft materials resorbed faster than brushite and more bone formation was achieved. There was no significant difference in the amount of bone formed between the two types of monetite grafts. The implanted brushite grafts underwent phase transformation to form hydroxyapatite, which ultimately limited bioresorption. However, this was not observed in both types of monetite grafts. In summary, both autoclaving and dry heating the preset brushite cement grafts resulted in monetite biomaterials which were more resorbable with potential to be investigated and optimized for orthopaedic and maxillofacial bone repair and regeneration applications.

STATEMENT OF SIGNIFICANCE

We present in this original research article a comparison between dicalcium phosphate cement based grafts (brushite and 2 types of monetite grafts prepared by wet and dry thermal processing) with regards to resorption and bone formation in vivo after orthotopic implantation in rabbit condylar femural region. To the best of our knowledge this is the first in vivo study that reports a comparison resorption and bone formation using brushite and two types of monetite biomaterials. Also, we have included in the manuscript a summary of all the in vivo studies performed on brushite and monetite biomaterials to date. This includes cement composition, physical properties (porosity and surface area), implantation and histomorphometrical details such as animal species, site of implantation, observation period, percentage bone tissue formation and residual graft material. In addition, we calculated the percentage resorption of graft materials based upon various implantation sites and included that into the discussion section. The results of this original research provides greater understanding of the resorption processes of dicalcium phosphate based grafts, allowing preparation of bone substitute materials with more predictable resorption profiles in future.

Local delivery of iron chelators reduces in vivo remodeling of a calcium phosphate bone graft substitute

Iron chelators are known activators of the Hypoxia Includible Factor-1α (HIF-1α) pathway, a critical cellular pathway involved in angiogenic responses to hypoxia. Local delivery of these chelators has shown promise in bone tissue engineering strategies by inducing angiogenesis and osteogenesis. Hypoxic microenvironments are also a stimulus for osteoclast differentiation and resorptive activity, a process likely mediated by HIF-1α. In vitro, low doses of the iron chelator Deferoxamine (DFO) has shown to induce HIF-1α mediated osteoclast formation and function. However other studies have proposed an opposite in vitro effect likely through HIF independent mechanisms. To investigate use of these medications in bioceramic based bone tissue engineering strategies this study aimed to determine the in vivo effect of local delivery of iron chelators on bioceramic remodeling. A non-weight bearing cranial onlay model was used to assess monetite resorption and new bone formation in the presence or absence of a repeated delivery of two iron chelators, DFO and 1,10 Phenanthroline (PHT) at doses known to induce HIF. We found a marked reduction graft resorption and remodeling associated with iron chelation. This was correlated to a 3-fold reduction in osteoclast number at the bone graft interface. Iron is needed for mitochondrial biogenesis during osteoclastic differentiation and reducing extracellular iron levels may inhibit this process and possibly overpower any HIF induced osteoclast formation. Our findings suggest that these inexpensive and widely available molecules may be used to locally reduce bioceramic scaffold resorption and encourages future investigations of iron chelators as bone anti-resorptive agents in other clinical contexts.

STATEMENT OF SIGNIFICANCE

Low doses of iron chelators can induce angiogenesis and osteogenesis in repairing bone by stimulating the oxygen sensitive gene; hypoxia inducible factor. These medications have potential to augment bioceramic based bone tissue engineering strategies without the downsides of protein-based growth factors. HIF activation is also known to stimulate osteoclast-mediated resorption and could potentially accelerate remodeling of biocermaics, however we have shown that the local delivery of iron chelation at doses known to induce HIF resulted in a reduction of monetite resorption and a significant decrease in osteoclast number at the bone graft interface. This maybe due to HIF independent mechanism. This is the first study to show a local effect of iron chelators in vivo on osteoclast-mediated resorption. This opens the potential of further study of these bifunctional medications to modulate resorption of biocermaics in environments where a prolonged presence of material is desired for graft site stability. Moreover these safe widely used medications can be explored to locally reduce osteoclasts in pathological bone resorption.

Oral antimicrobial peptides: Types and role in the oral cavity

Antimicrobial peptides (AMPs) are a wide-ranging class of host-defense molecules that act early to contest against microbial invasion and challenge. These are small cationic peptides that play an important in the development of innate immunity. In the oral cavity, the AMPs are produced by the salivary glands and the oral epithelium and serve defensive purposes. The aim of this review was to discuss the types and functions of oral AMPs and their role in combating microorganisms and infections in the oral cavity.

Oral antimicrobial peptides: Types and role in the oral cavity

Antimicrobial peptides (AMPs) are a wide-ranging class of host-defense molecules that act early to contest against microbial invasion and challenge. These are small cationic peptides that play an important in the development of innate immunity. In the oral cavity, the AMPs are produced by the salivary glands and the oral epithelium and serve defensive purposes. The aim of this review was to discuss the types and functions of oral AMPs and their role in combating microorganisms and infections in the oral cavity.

Controlling Bone Graft Substitute Microstructure to Improve Bone Augmentation

Vertical bone augmentation procedures are frequently carried out to allow successful placement of dental implants in otherwise atrophic ridges and represent one of the most common bone grafting procedures currently performed. Onlay autografting is one of the most prevalent and predictable techniques to achieve this; however, there are several well documented complications and drawbacks associated with it and synthetic alternatives are being sought. Monetite is a bioresorbable dicalcium phosphate with osteoconductive and osteoinductive potential that has been previously investigated for onlay bone grafting and it is routinely made by autoclaving brushite to simultaneously sterilize and phase convert. In this study, monetite disc-shaped grafts are produced by both wet and dry heating methods which alter their physical properties such as porosity, surface area, and mechanical strength. Histological observations after 12 weeks of onlay grafting on rabbit calvaria reveal higher bone volume (38%) in autoclaved monetite grafts in comparison with the dry heated monetite grafts (26%). The vertical bone height gained is similar for both the types of monetite grafts (up to 3.2 mm). However, it is observed that the augmented bone height is greater in the lateral than the medial areas of both types of monetite grafts. It is also noted that the higher porosity of autoclaved monetite grafts increases the bioresorbability, whereas the dry heated monetite grafts having lower porosity but higher surface area resorb to a significantly lesser extent. This study provides information regarding two types of monetite onlay grafts prepared with different physical properties that can be further investigated for clinical vertical bone augmentation applications.

Identification And Endodontic Treatment Of Threecanalled Maxillary First Premolar

Maxillary premolars exhibit variable root canal morphology, but it is quite rare to find three canals in their root system. The aim of this case report is to present the diagnosis and clinical management of a patient with anatomical variation of having three root canals in the maxillary first premolar. Three-canalled maxillary premolars are quite an endodontic challenge. A discussion is provided here to facilitate the early recognition of these canals, access cavity modifications for better intra-canal preparation and obturation procedures. Clinicians are required to be aware of the anatomical variations they may encounter when dealing with maxillary premolars and should be trained to apply this knowledge in the clinical scenario.

Rare case of accidental fire and burns caused by e-cigarette batteries

E-cigarettes have become very popular among adult smokers, and many users carry e-cigarette devices and their components on their person. We present a case of a 35-year-old man who was admitted to our regional burns unit after his clothing was set-alight following the self-combustion of an e-cigarette lithium battery that was in his pocket. The patient had sustained a 1.5% mixed depth burn to the lateral aspect of his right thigh. Ward debridement under local anaesthetic was performed to remove clothing residue and reduce the risk of tattooing. Following conservative management with outpatient dressings, the burn wound healed by day 56.

Allergic effects of the residual monomer used in denture base acrylic resins

Denture base resins are extensively used in dentistry for a variety of purposes. These materials can be classified as chemical, heat, light, and microwave polymerization materials depending upon the factor which starts the polymerization reaction. Their applications include use during denture base construction, relining existing dentures, and for fabrication of orthodontic removable appliances. There have been increased concerns regarding the safe clinical application of these materials as their biodegradation in the oral environment leads to harmful effects. Along with local side effects, the materials have certain occupational hazards, and numerous studies can be found in the literature mentioning those. The purpose of this article is to outline the cytotoxic consequences of denture base acrylic resins and clinical recommendations for their use.

Mechanisms of in Vivo Degradation and Resorption of Calcium Phosphate Based Biomaterials

Calcium phosphate ceramic materials are extensively used for bone replacement and regeneration in orthopedic, dental, and maxillofacial surgical applications. In order for these biomaterials to work effectively it is imperative that they undergo the process of degradation and resorption in vivo. This allows for the space to be created for the new bone tissue to form and infiltrate within the implanted graft material. Several factors affect the biodegradation and resorption of calcium phosphate materials after implantation. Various cell types are involved in the degradation process by phagocytic mechanisms (monocytes/macrophages, fibroblasts, osteoblasts) or via an acidic mechanism to reduce the micro-environmental pH which results in demineralization of the cement matrix and resorption via osteoclasts. These cells exert their degradation effects directly or indirectly through the cytokine growth factor secretion and their sensitivity and response to these biomolecules. This article discusses the mechanisms of calcium phosphate material degradation in vivo.

In vitro degradation and in vivo resorption of dicalcium phosphate cement based grafts

There are two types of DCP: dihydrated (brushite) and anhydrous (monetite). After implantation, brushite converts to hydroxyapatite (HA) which resorbs very slowly. This conversion is not observed after implantation of monetite cements and result in a greater of resorption. The precise mechanisms of resorption and degradation however of these ceramics remain uncertain. This study was designed to investigate the effect of: porosity, surface area and hydration on in vitro degradation and in vivo resorption of DCP. Brushite and two types of monetite cement based grafts (produced by wet and dry thermal conversion) were aged in phosphate buffered saline (PBS) and bovine serum solutions in vitro and were implanted subcutaneously in rats. Here we show that for high relative porosity grafts (50-65%), solubility and surface area does not play a significant role towards in vitro mass loss with disintegration and fragmentation being the main factors dictating mass loss. For grafts having lower relative porosity (35-45%), solubility plays a more crucial role in mass loss during in vitro ageing and in vivo resorption. Also, serum inhibited dissolution and the formation of HA in brushite cements. However, when aged in PBS, brushite undergoes phase conversion to a mixture of octacalcium phosphate (OCP) and HA. This phase conversion was not observed for monetite upon ageing (in both serum and PBS) or in subcutaneous implantation. This study provides greater understanding of the degradation and resorption process of DCP based grafts, allowing us to prepare bone replacement materials with more predictable resorption profiles.

Nociception and role of immune system in pain

Both pain and inflammation are protective responses. However, these self-limiting conditions (with well-established negative feedback loops) become pathological if left uncontrolled. Both pain and inflammation can interact with each other in a multi-dimensional manner. These interactions are known to create an array of 'difficult to manage' pathologies. This review explains in detail the role of immune system and the related cells in peripheral sensitization and neurogenic inflammation. Various neuro-immune interactions are analyzed at peripheral, sensory and central nervous system levels. Innate immunity plays a critical role in central sensitization and in establishing acute pain as chronic condition. Moreover, inflammatory mediators also exhibit psychological effects, thus contributing towards the emotional elements associated with pain. However, there is also a considerable anti-inflammatory and analgesic role of immune system. This review also attempts to enlist various novel pharmacological approaches that exhibit their actions through modification of neuro-immune interface.

Macrophages, Foreign Body Giant Cells and Their Response to Implantable Biomaterials

All biomaterials, when implanted in vivo, elicit cellular and tissue responses. These responses include the inflammatory and wound healing responses, foreign body reactions, and fibrous encapsulation of the implanted materials. Macrophages are myeloid immune cells that are tactically situated throughout the tissues, where they ingest and degrade dead cells and foreign materials in addition to orchestrating inflammatory processes. Macrophages and their fused morphologic variants, the multinucleated giant cells, which include the foreign body giant cells (FBGCs) are the dominant early responders to biomaterial implantation and remain at biomaterial-tissue interfaces for the lifetime of the device. An essential aspect of macrophage function in the body is to mediate degradation of bio-resorbable materials including bone through extracellular degradation and phagocytosis. Biomaterial surface properties play a crucial role in modulating the foreign body reaction in the first couple of weeks following implantation. The foreign body reaction may impact biocompatibility of implantation devices and may considerably impact short- and long-term success in tissue engineering and regenerative medicine, necessitating a clear understanding of the foreign body reaction to different implantation materials. The focus of this review article is on the interactions of macrophages and foreign body giant cells with biomaterial surfaces, and the physical, chemical and morphological characteristics of biomaterial surfaces that play a role in regulating the foreign body response. Events in the foreign body response include protein adsorption, adhesion of monocytes/macrophages, fusion to form FBGCs, and the consequent modification of the biomaterial surface. The effect of physico-chemical cues on macrophages is not well known and there is a complex interplay between biomaterial properties and those that result from interactions with the local environment. By having a better understanding of the role of macrophages in the tissue healing processes, especially in events that follow biomaterial implantation, we can design novel biomaterials-based tissue-engineered constructs that elicit a favorable immune response upon implantation and perform for their intended applications.

Characterization of biomimetic calcium phosphate labeled with fluorescent dextran for quantification of osteoclastic activity

Bone resorbing osteoclasts represent an important therapeutic target for diseases associated with bone and joint destruction, such as rheumatoid arthritis, periodontitis, and osteoporosis. The quantification of osteoclast resorptive activity in vitro is widely used for screening new anti-resorptive medications. The aim of this paper was to develop a simplified semi-automated method for the quantification of osteoclastic resorption using fluorescently labeled biomimetic mineral layers which can replace time intensive, often subjective and clearly non-sustainable use of translucent slices of tusks from vulnerable or endangered species such as the elephant. Osteoclasts were formed from RAW 264.7 mouse monocyte cell line using the pro-resorptive cytokine receptor activator of nuclear factor kappa-B ligand (RANKL). We confirmed that fluorescent labeling did not interfere with the biomimetic features of hydroxyapatite, and developed an automated method for quantifying osteoclastic resorption. Correlation between our assay and traditional manual measurement techniques was found to be very strong (R(2)=0.99). In addition, we modified the technique to provide depth and volume data of the resorption pits by confocal imaging at defined depths. Thus, our method allows automatic quantification of total osteoclastic resorption as well as additional data not obtainable by the current tusk slice technique offering a better alternative for high throughput screening of potential antiresorptives.

Bone Replacement Materials and Techniques Used for Achieving Vertical Alveolar Bone Augmentation

Alveolar bone augmentation in vertical dimension remains the holy grail of periodontal tissue engineering. Successful dental implant placement for restoration of edentulous sites depends on the quality and quantity of alveolar bone available in all spatial dimensions. There are several surgical techniques used alone or in combination with natural or synthetic graft materials to achieve vertical alveolar bone augmentation. While continuously improving surgical techniques combined with the use of auto- or allografts provide the most predictable clinical outcomes, their success often depends on the status of recipient tissues. The morbidity associated with donor sites for auto-grafts makes these techniques less appealing to both patients and clinicians. New developments in material sciences offer a range of synthetic replacements for natural grafts to address the shortcoming of a second surgical site and relatively high resorption rates. This narrative review focuses on existing techniques, natural tissues and synthetic biomaterials commonly used to achieve vertical bone height gain in order to successfully restore edentulous ridges with implant-supported prostheses.

Matrix metalloproteinases and their pathological upregulation in multiple sclerosis: an overview

Matrix metalloproteinases (MMPs) are a family of extracellular proteases associated with extracellular matrix remodeling. They are involved in many physiological and reparative processes. MMPs can break down all extracellular constituents; therefore, their expression is very tightly regulated and their abnormal activity or over production has been linked to many diseases including multiple sclerosis (MS) which is a leading cause of non-traumatic disability in young adults in North America. Recently many studies, both in animals and humans, have been conducted to better elucidate the underlying causes, mechanisms and pathophysiology of MS. In this review, we discuss the potential role of pathological upregulation of MMPs in MS and future challenges which if properly addressed might help in development of potential cure for this disease.

Reproducible quantification of osteoclastic activity: characterization of a biomimetic calcium phosphate assay

Osteoclasts are responsible for bone and joint destruction in rheumatoid arthritis, periodontitis, and osteoporosis. Animal tusk slice assays are standard for evaluating the effect of therapeutics on these cells. However, in addition to batch-to-batch variability inherent to animal tusks, their use is clearly not sustainable. Our objective was to develop and characterize a biomimetic calcium phosphate assay based on the use of phase pure hydroxyapatite coated as a thin film on the surface of culture plates, to facilitate the reproducible quantification of osteoclast resorptive activity. Osteoclasts were formed from RAW 264.7 mouse monocyte cell line using a pro-resorptive cytokine RANKL (50 ng/mL). No change in substrate appearance was noted after culture with media without cells, or undifferentiated monocytes. Only in the presence of osteoclasts localized areas of calcium phosphate dissolution were observed. The total area resorbed positively correlated with the osteoclast numbers (R(2) = 0.99). The resorbed area was significantly increased by the addition of RANKL, and decreased after application of known inhibitors of osteoclast resorptive activity, calcitonin (10 μM), or alendronate (100 μM). Thus, calcium phosphate coated substrates allow reliable monitoring of osteoclast resorptive activity and offer an alternative to animal tusk slice assays.

The effect of autoclaving on the physical and biological properties of dicalcium phosphate dihydrate bioceramics: brushite vs. monetite

Dicalcium phosphate dihydrate (brushite) is an osteoconductive biomaterial with great potential as a bioresorbable cement for bone regeneration. Preset brushite cement can be dehydrated into dicalcium phosphate anhydrous (monetite) bioceramics by autoclaving. This heat treatment results in changes in the physical characteristics of the material, improving in vivo bioresorption. This property is a great advantage in bone regeneration; however, it is not known how autoclaving brushite preset cement might improve its capacity to regenerate bone. This study was designed to compare brushite bioceramics with monetite bioceramics in terms of physical characteristics in vitro, and in vivo performance upon bone implantation. In this study we observed that monetite bioceramics prepared by autoclaving preset brushite cements had higher porosity, interconnected porosity and specific surface area than their brushite precursors. In vitro cell culture experiments revealed that bone marrow cells expressed higher levels of osteogenic genes Runx2, Opn, and Alp when the cells were cultured on monetite ceramics rather than on brushite ones. In vivo experiments revealed that monetite bioceramics resorbed faster than brushite ones and were more infiltrated with newly formed bone. In summary, autoclaving preset brushite cements results in a material with improved properties for bone regeneration procedures.