Biocompatibility and Durability of Diazonium Adhesives on Dental Alloys.

PURPOSE: A new type of diazonium-based adhesive has been recently developed by our team to bind dental alloys (Titanium, stainless steel, and cobalt chromium) to dental polymers. Here, we explored the endurance of the resulting adhesive after thermal-cycling and autoclave aging. MATERIALS AND METHODS: Polished samples of titanium (Ti), stainless steel (SS) and cobalt chromium (Co-Cr) were coated with a diazonium-based adhesive. Untreated samples served as controls (n = 12 per each condition). X-ray photoelectron spectroscopy (XPS) was performed to characterize the elemental compositions of the different surfaces. Biocompatibility of the coated alloys was assessed with human gingival fibroblasts (HGF). Inductively coupled plasma (ICP) and total organic carbon (TOC) analyses were used to quantify the ions and organic matters released from the diazonium coated alloys. Endurance of the adhesives was assessed by exposing the samples to autoclaving and thermal-cycling. The tensile strength of the poly(methylmethacrylate) (PMMA)-alloy bond was also tested. RESULTS: Results of mechanical testing demonstrated a higher endurance of the coated CoCr, Ti, and SS compared to the uncoated alloys. The human fibroblasts cultured on the substrates remained alive and metabolically active, and the coatings did not release significant amounts of toxic chemicals in solutions. CONCLUSIONS: The results further support the use of diazonium-based adhesives as new coupling agents for dental applications.

Marginal Discrepancies of Monolithic Zirconia Crowns: The Influence of Preparation Designs and Sintering Techniques.

PURPOSE: The marginal fit is an essential component for the clinical success of prosthodontic restorations. The aim of this study was to investigate the influence of different abutment finish line widths and crown thicknesses on the marginal fit of zirconia crowns fabricated using either standard or fast sintering protocols. MATERIALS AND METHODS: Six titanium abutments were fabricated for receiving zirconia molar crowns. Crowns were designed virtually and milled from partially sintered zirconia blanks and divided into 12 groups (n = 10/group). Crowns in groups 1 to 6 were sintered by standard sintering, while those in groups 7 to 12 were sintered by fast sintering. Groups were further categorized according to abutment finish line and crown thickness: G1/G7 (0.5 mm chamfer, 0.8 mm thick); G2/G8 (0.5 mm chamfer, 1.5 mm thick); G3/G9 (1.0 mm chamfer, 0.8 mm thick); G4/10 (1.0 mm chamfer, 1.5 mm thick); G5/G11 (1.2 mm chamfer, 0.8 mm thick); G6/G12 (1.2 mm chamfer, 1.5 mm thick). The marginal gaps were assessed at 8 locations using digital microscopy. The linear mixed effect model analysis was performed at a significance level of 0.05. RESULTS: All vertical marginal gaps were within the clinically acceptable range (∼11-52 µm). G8 (FS, 0.5 mm chamfer, 1.5 mm thick) demonstrated the largest gaps (47.95 µm, 95% CI: 44.57-51.23), whereas G3 (SS, 1.0 mm chamfer, 0.8 thick) had the smallest marginal gap (14.43 µm, 95% CI: 11.15-17.71). A linear mixed effect models showed significant differences for the interaction between finish line × crown thickness × sintering (F = 18.96, p < 0.001). The lingual surfaces showed the largest gaps in both sintering protocols, while the mesial and mesiobuccal surfaces demonstrated the smallest gaps. CONCLUSIONS: There was a significant interaction between finish line widths, crown thickness, and sintering protocol on the marginal gaps in both sintering protocols; 1.0 mm finish line preparations with either 0.8 mm or 1.5 mm occlusal reduction had better marginal fit in both sintering protocols compared to 0.5 mm or 1.2 mm finish lines. Smaller marginal discrepancies were observed for standard sintering crowns with a 0.5 mm finish line and 1.5 mm occlusal reduction. Conservative occlusal reduction should be accompanied with a 1.2 mm finish line to obtain better marginal fit for full-contoured zirconia crowns.

The antidepressant drug, sertraline, hinders bone healing and osseointegration in rats' tibiae.

AIM: Selective serotonin reuptake inhibitors (SSRIs) are one of the most common antidepressant drugs. SSRI use is associated with increased risk of bone fracture and titanium implant failure. The aim of this in vivo study was to investigate the effect of SSRIs on osseointegration and bone healing. MATERIALS AND METHODS: On a total of 24 Sprague-Dawley rats, a custom-made titanium implant was placed in the left tibia, while a unicortical defect was created in the right tibia. Rats were assigned randomly into two groups and received a daily dose of either sertraline (5 mg/kg) or saline. After two weeks, they were euthanized and bone healing and osseointegration were assessed by micro-CT and histology. RESULTS: Bone formation in bone defects was significantly lower (p < 0.05) in sertraline-treated rats (BV/TV = 20.67 ± 11.98%) compared to the controls (BV/TV = 37.87 ± 9.56%). Furthermore, the percentage of osseointegration was significantly lower (p < 0.05) in sertraline-treated rats (34.40 ± 7.17%) compared to the controls (54.37 ± 8.58%). CONCLUSION: Sertraline hinders bone healing and implant osseointegration.

Platelet concentrates for bone regeneration: Current evidence and future challenges.

Activated platelet concentrates are autologous blood preparations containing supraphysiological concentration of platelets. Platelet concentrates are commonly used for bone regeneration purposes based on the fact that growth factors released from activated platelets alpha granules have osteoinductive effects on bone cells. Although most preclinical and clinical studies show that platelet concentrates improve the outcomes of bone regeneration procedures, some studies reported conflicting results and even negative effects on bone healing. Several confounding parameters have been suggested as possible reasons for such inconsistencies (i.e. preparation and activation methods). However, heterogeneity in clinical studies makes drawing evidence-based conclusions difficult. On the other hand, recent findings show that the constituents of platelets dense granules (i.e. serotonin, ATP, Ca2+) have potential inhibitory effects on bone metabolism. Accordingly, we suggest that a partial explanation for the conflicting results could be the potential negative effects that dense granules may have on bone healing.

Two-Dimensional Magnesium Phosphate Nanosheets Form Highly Thixotropic Gels That Up-Regulate Bone Formation.

Hydrogels composed of two-dimensional (2D) nanomaterials have become an important alternative to replace traditional inorganic scaffolds for tissue engineering. Here, we describe a novel nanocrystalline material with 2D morphology that was synthesized by tuning the crystallization of the sodium-magnesium-phosphate system. We discovered that the sodium ion can regulate the precipitation of magnesium phosphate by interacting with the crystal's surface causing a preferential crystal growth that results in 2D morphology. The 2D nanomaterial gave rise to a physical hydrogel that presented extreme thixotropy, injectability, biocompatibility, bioresorption, and long-term stability. The nanocrystalline material was characterized in vitro and in vivo and we discovered that it presented unique biological properties. Magnesium phosphate nanosheets accelerated bone healing and osseointegration by enhancing collagen formation, osteoblasts differentiation, and osteoclasts proliferation through up-regulation of COL1A1, RunX2, ALP, OCN, and OPN. In summary, the 2D magnesium phosphate nanosheets could bring a paradigm shift in the field of minimally invasive orthopedic and craniofacial interventions because it is the only material available that can be injected through high gauge needles into bone defects in order to accelerate bone healing and osseointegration.

Systemic administration of omeprazole interferes with bone healing and implant osseointegration: an in vivo study on rat tibiae.

BACKGROUND: Proton pump inhibitors, over-the-counter drugs taken by millions of patients, diminish bone accrual. Accordingly, we hypothesized that these drugs could impair bone healing and implant osseointegration. This study investigated the effect of post-operative systemic administration of omeprazole on bone healing and implant osseointegration in rat tibiae. METHODS: In 24 Sprague-Dawley rats, a titanium implant was placed in the left tibia, and a bone defect was created in the right tibia. During the 2 weeks following surgery, 12 rats were treated with omeprazole (5 mg/kg, daily) and the other 12 with saline. Then, after euthanasia, the volume (mm(3) ) of the cortical defect and the percentages of newly formed bone in the defect, were assessed using microcomputed tomography; peri-implant bone volume/tissue volume and bone-implant contact percentage were assessed by histomorphometry. RESULTS: Omeprazole-treated rats presented larger cortical defects (2.75 ± 0.59 mm(3) , p = 0.003 versus 2.11 ± 0.36 mm(3) ; p = 0.002) and a lower percentage of newly formed bone in the defects (28.62 ± 13.12; 45.89 ± 9.73; p = 0.003) than controls. Omeprazole-treated rats presented lower peri-implant bone volume/tissue volume (14.3 ± 7.3% versus 30.8 ± 11.0%; p < 0.001) and bone-implant contact (23.3 ± 10.8% versus 41.8 ± 13.3%; p < 0.001) than controls. CONCLUSION: Systemically administered omeprazole impairs bone healing and implant osseointegration.

Propranolol enhances bone healing and implant osseointegration in rats tibiae.

BACKGROUND: Propranolol, a non-selective ß-blocker widely used to treat cardiovascular conditions, favours bone accrual. Accordingly, we hypothesized that propranolol could be useful for improving bone healing and osseointegration. This in vivo study was designed to investigate the effect of propranolol on bone healing and osseointegration in rats' tibiae. METHODS: On 24 Sprague-Dawley rats, a unicortical defect was created in the right tibial metaphysis of each rat and a custom-made titanium implant was placed in the left tibia. Animals were then assigned into two groups (n = 12, each group) and treated daily with either propranolol (5 mg/kg: subcutaneous) or saline, for 2 weeks. Then, after killing, the volume of the cortical defects (mm3) and the percentages of newly formed bone in the defects, were assessed with microcomputed tomography; bone-implant contact percentage and peri-implant bone volume/tissue volume were assessed by histomorphometry. RESULT: Propranolol-treated rats presented smaller cortical defects (1.56 ± 0.28 mm3 versus 2.04 ± 0.29 mm3 , p < 0.001) with more bone volume/tissue volume (60.6 ± 7.9% versus 41.1 ± 10.2%, p < 0.001) compared to saline-treated rats. Propranolol also enhanced osseointegration as propranolol-treated rats presented higher bone-implant-contact (65.0 ± 13.1% versus 42.5 ± 8.8%, p < 0.001) and peri-implant bone volume/Tissue volume (73.8 ± 10.1% versus 56.9 ± 5.7%, p = 0.007) than saline-treated rats. CONCLUSION: Propranolol enhanced bone healing and implant osseointegration.

Rehabilitation of a Completely Edentulous Patient with Nonreducible Bilateral Anterior Dislocation of the Temporomandibular Joint: A Prosthodontic Challenge-Clinical Report.

Nonreduced bilateral anterior dislocation of the temporomandibular joint (TMJ) is an extremely rare condition, and its prosthodontic rehabilitation is a clinical challenge, especially in patients who refuse to or cannot undergo surgery. There are no previous clinical reports of successful or standardized prosthetic rehabilitation approaches for patients with this condition. This clinical report describes the successful prosthodontic management of an edentulous patient with nonreduced bilateral anterior dislocation of the TMJ.

Anti-VEGFs hinder bone healing and implant osseointegration in rat tibiae.

AIM: To assess the effect of anti-vascular endothelial growth factors (VEGF) on bone healing (defect volume) and implant osseointegration (bone-implant contact per cent) in rat tibia. MATERIALS AND METHODS: In Sprague-Dawley rats (n = 36), a unicortical defect was created in the right tibia and a titanium implant was placed in the left tibia of each rat. Rats were assigned into three groups and received either anti-vascular endothelial growth factor neutralizing antibody, Ranibizumab or saline (control). Two weeks following surgery, rats were euthanized and bone samples were retrieved. Bone healing and osseointegration were assessed using micro-CT and histomorphometry. One-way anova followed by the Tukey's test was used for data analyses. RESULTS: The volume of the bone defects in the anti-VEGF group (2.48 ± 0.33 mm(3) ) was larger (p = 0.026) than in the controls (2.11 ± 0.36 mm(3) ) as measured by µ-CT. Bone-implant contact percent in the anti-VEGF (19.9 ± 9.4%) and Ranibizumab (21.7 ± 9.2%) groups were lower (p < 0.00) than in the control group (41.8 ± 12.4%). CONCLUSIONS: The results of this study suggest that drugs that inhibit the activity of vascular endothelial growth factor (i.e. anti-VEGF) may hinder bone healing and implant osseointegration in rat tibiae.

Are interventions for accelerating orthodontic tooth movement effective?

DATA SOURCES: Pubmed, Embase, Sciences Citation Index, Cochrane Central Register of Controlled Trials (CENTRAL) and grey literature database of SIGLE were searched from January 1, 1990 to August 20, 2011 with no language restrictions. STUDY SELECTION: Randomised controlled trials (RCTs) or quasi-RCTs in which the participants were healthy and received additional interventions to conventional orthodontic treatment for accelerating tooth movements were included. Subjects with defects in oral and maxillofacial regions (ie, cleft lip/palate), dental pathologies and medical conditions were excluded. DATA EXTRACTION AND SYNTHESIS: Studies were selected by two independent reviewers and disagreements were resolved by discussion with a third reviewer. The primary outcomes included accumulative moved distance (AMD) or movement rate (MR) and time required to move the tooth to its destination. Secondary outcomes were pain improvement, anchorage loss, periodontal health, orthodontic caries, pulp vitality and root resorption. The reviewers performed statistical pooling, where possible, according to a priori criteria on the basis of comparability of patient type, treatments and outcomes measured and risk of bias. The reviewers tested for heterogeneity, publication bias and sensitivity. A quality assessment test was conducted to evaluate the method used to measure AMD. RESULTS: The authors selected seven RCTs and two quasi-RCTs, which included a total of 101 patients with an age range of 12-26.3 years. Eight studies compared four intervention methods to no intervention group (control group). From them, four studies assessed low laser therapy (LLL), two evaluated corticotomy (CC), one assessed electrical current therapy (EC) and one evaluated pulsed electromagnetic field (PEF). Another study compared dentoalveolar distraction (DAD) vs periodontal distraction (PDD).Quality assessment scores showed that only two studies were of high quality, five studies were of medium quality, while two studies were of low quality. All studies, except one, compared left and right sides of the same participant (split mouth design), and measured the AMD.The method for measuring AMD was reliable in three studies, relatively reliable in one study and unreliable in four studies. The authors only performed pooled AMD mean meta-analysis for the LLL studies. The meta-analysis showed pooled mean AMD of 0.32 (95% confidence interval (CI), 20.04, 0.68), 0.76 (95% CI, 20.14, 1.65), and 0.73 (95% CI, 20.68, 2.14) for one month, two months and three months, respectively. Two LLL studies showed no differences regarding periodontal health and two LLL studies showed no differences in root resorption between LLL intervention and control groups. Compared to control group, one study reported that CS had significantly higher MR and another study showed that CS exhibited larger AMD for one month, two months, three months and four months. Two studies revealed that CS did not show any difference in the periodontal health status. One study reported the EC showed significantly larger AMD for one month, whereas another study reported that PEF induced larger AMD for five + 0.6 months. DAD showed faster MR and less anchorage loss compared to PDD. Teeth remained vital in both DAD and PDD interventions and one out of six cases presented root resorption in the PDD group. CONCLUSIONS: Among the five interventions corticotomy is effective and safe to accelerate orthodontic tooth movement, low-level laser therapy was unable to accelerate orthodontic tooth movement. The level of evidence does not support whether electrical current and pulsed electromagnetic fields are effective in accelerating orthodontic tooth movement and dentoalveolar or periodontal distraction is promising in accelerating orthodontic tooth movement.

Disclosing Agent for Resin Composite Based on Adsorption Surface Treatment.

A composite disclosing agent can help dentists distinguish resin boundaries from the tooth structure and facilitate its complete removal while avoiding damage to the surrounding sound tooth structures. In this study we characterized the interaction of composite resin with various organic molecules with functional groups comparable to composite monomers which resulted in the development of a composite disclosing agent. The adhesion of these molecules to composite and tooth enamel and the ability to selectively stain composite were verified using spectrophotometry and other techniques. The optimal staining conditions were confirmed clinically in a pilot study on orthodontic patients. Our results indicated that a molecule with phenyl groups resembling composite monomers, such as methyl salicylate, was able to adsorb to composite resin through Van Der Waals forces and not tooth enamel and serve as a primer for a disclosing agent.

Narghile (water pipe) smoking among university students in Jordan: prevalence, pattern and beliefs.

BACKGROUND AND OBJECTIVES: Narghile is becoming the favorite form of tobacco use by youth globally. This problem has received more attention in recent years. The aim of this study was to investigate the prevalence and pattern of narghile use among students in three public Jordanian universities; to assess their beliefs about narghile's adverse health consequences; and to evaluate their awareness of oral health and oral hygiene. METHODS: The study was a cross-sectional survey of university students. A self-administered, anonymous questionnaire was distributed randomly to university students in three public Jordanian universities during December, 2008. The questionnaire was designed to ask specific questions that are related to smoking in general, and to narghile smoking in specific. There were also questions about oral health awareness and oral hygiene practices. RESULTS: 36.8% of the surveyed sample indicated they were smokers comprising 61.9% of the male students and 10.7% of the female students in the study sample. Cigarettes and narghile were the preferred smoking methods among male students (42%). On the other hand, female students preferred narghile only (53%). Parental smoking status but not their educational level was associated with the students smoking status. Smokers had also significantly poor dental attendance and poor oral hygiene habits. CONCLUSION: This study confirmed the spreading narghile epidemic among young people in Jordan like the neighboring countries of the Eastern Mediterranean region. Alarming signs were the poor oral health awareness among students particularly smokers.

Clinical orthodontic management during the COVID-19 pandemic.

OBJECTIVES: To provide a comprehensive summary of the implications of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and coronavirus disease 2019 (COVID-19) on orthodontic treatment, contingency management, and provision of emergency orthodontic treatment, using currently available data and literature. MATERIALS AND METHODS: Orthodontically relevant sources of information were searched using electronic databases including PubMed and Google Scholar and current reports from major health bodies such as Centers for Disease Control and Prevention, World Health Organization, National Institutes of Health, and major national orthodontic associations. RESULTS: Where available, peer-reviewed and more recent publications were given priority. Due to the rapidly evolving nature of COVID-19 and limitations in quality of evidence, a narrative synthesis was undertaken. Relevant to orthodontics, human-to human transmission of SARS-CoV-2 occurs predominantly through the respiratory tract via droplets, secretions (cough, sneeze), and or direct contact, where the virus enters the mucous membrane of the mouth, nose, and eyes. The virus can remain stable for days on plastic and stainless steel. Most infected persons experience a mild form of disease, but those with advanced age or underlying comorbidities may suffer severe respiratory and multiorgan complications. CONCLUSIONS: During the spread of the COVID-19 pandemic, elective orthodontic treatment should be suspended and resumed only when permitted by federal, provincial, and local health regulatory authorities. Emergency orthodontic treatment can be provided by following a contingency plan founded on effective communication and triage. Treatment advice should be delivered remotely first when possible, and where necessary, in-person treatment can be performed in a well-prepared operatory following the necessary precautions and infection prevention and control (IPAC) protocol.

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.

Composition and characteristics of trabecular bone in osteoporosis and osteoarthritis.

BACKGROUND: Bone strength depends on multiple factors such as bone density, architecture and composition turnover. However, the role these factors play in osteoporotic fractures is not well understood. PURPOSE: The aim of this study was to analyze trabecular bone architecture, and its crystal and organic composition in humans, by comparing samples taken from patients who had a hip fracture (HF) and individuals with hip osteoarthritis (HOA). METHODS: The study included 31 HF patients and 42 cases of HOA who underwent joint replacement surgery between 1/1/2013 and 31/12/2013. Trabecular bone samples were collected from the femoral heads and analyzed using a dual-energy X-ray absorptiometry, micro-CT, and solid-state high-resolution magic-angle-spinning nuclear magnetic resonance (MAS-NMR) spectroscopy. RESULTS: No differences in proton or phosphorus concentration were found between the two groups using 1H single pulse, 31P single pulse, 31P single pulse with proton decoupling NMR spectroscopy, in hydroxyapatite (HA) c-axis or a-axis crystal length. Bone volume fraction (BV/TV), trabecular number (Tb.N), and bone mineral density (BMD) were higher in the HO group than in the HF group [28.6% ± 10.5 vs 20.3% ± 6.6 (p = 0.026); 2.58 mm-1 ± 1.57 vs 1.5 mm-1 ± 0.79 (p = 0.005); and 0.39 g/cm2 ± 0.10 vs. 0.28 g/cm2 ± 0.05 (p = 0.002), respectively]. The trabecular separation (Tp.Sp) was lower in the HO group 0.42 mm ± 0.23 compared with the HF group 0.58 mm ± 0.27 (p = 0.036). In the HO group, BMD was correlated with BV/TV (r = 0.704, p < 0.001), BMC (r = 0.853, p < 0.001), Tb.N (r = 0.653, p < 0.001), Tb.Sp (-0.561, p < 0.001) and 1H concentration (-0.580, p < 0.001) in the HO group. BMD was not correlated with BV/TV, Tb.Sp, Tb.Th, Tb.N, Tb.PF, 1H concentration or HA crystal size in the HF group. CONCLUSIONS: Patients with HO who did not sustain previous hip fractures had a higher femoral head BMD, BV/TV, and Tb.N than HF patients. In HO patients, BMD was positively correlated with the BV/TV and Tb.N and negatively correlated with the femoral head organic content and trabecular separation. Interestingly, these correlations were not found in HF patients with relatively lower bone densities. Therefore, osteoporotic patients with similar low bone densities could have significant microstructural differences. No differences were found between the two groups at a HA crystal level.

Low intensity pulsed ultrasound increases mandibular height and Col-II and VEGF expression in arthritic mice.

OBJECTIVE: Rheumatoid arthritis (RA) is a chronic inflammatory disease involving persistent inflammation resulting in cartilage and bone damage. RA can affect the temporomandibular joint (TMJ), and damage to the TMJ condyle can lead to craniofacial developmental disturbances, causing micrognathia, malocclusion, retrognathia, and increased overjet. Current treatments of TMJ arthritis are unsatisfactory. This pilot study aimed to investigate the effect of low intensity pulsed ultrasound (LIPUS) on the mandible and TMJ condyles in an RA mouse model using micro-computed tomography (Micro-CT), histologic, and immunohistochemical analyses. METHODS: MRL-lpr/lpr mice received LIPUS application to their TMJs for 20 min/day for 2 and 4 weeks. Micro-CT analysis measured condylar length and width, posterior mandibular height (P.M.H), mandibular ramus length (M.R.L), effective mandibular length (Ef.M.L), angular process length (A.P.L), mandibular plane (M.P), mandibular axis (M.Ax), and lower incisor height (L.I.H). Condylar cartilage thickness was histologically measured, and type II collagen (Col-II), vascular endothelial growth factor (VEGF), nuclear factor kappa-B ligand (RANKL), and osteoprotegerin (OPG) expression was analyzed using immunohistochemistry. RESULTS: Comparing the LIPUS-treated group with the control, P.M.H, M.R.L, and M.P were significantly greater in the LIPUS-treated group. Immunostaining for Col-II and VEGF was stronger in the LIPUS-treated group after 4 weeks. OPG showed slightly more expression in the LIPUS group. CONCLUSIONS: LIPUS may enhance mandibular and TMJ condylar bone formation in this RA mouse model by preventing any growth disturbances involved in inflammation. Further studies are recommended to analyze the effect of LIPUS on TMJ of RA in other animal models.

Combination of polyetherketoneketone scaffold and human mesenchymal stem cells from temporomandibular joint synovial fluid enhances bone regeneration.

Therapies using human mesenchymal stem cells (MSCs) combined with three-dimensional (3D) printed scaffolds are a promising strategy for bone grafting. But the harvest of MSCs still remains invasive for patients. Human synovial fluid MSCs (hSF-MSCs), which can be obtained by a minimally invasive needle-aspiration procedure, have been used for cartilage repair. However, little is known of hSF-MSCs in bone regeneration. Polyetherketoneketone (PEKK) is an attractive bone scaffold due to its mechanical properties comparable to bone. In this study, 3D-printed PEKK scaffolds were fabricated using laser sintering technique. hSF-MSCs were characterized and cultured on PEKK to evaluate their cell attachment, proliferation, and osteogenic potential. Rabbit calvarial critical-sized bone defects were created to test the bone regenerative effect of PEKK with hSF-MSCs. In vitro results showed that hSF-MSCs attached, proliferated, and were osteogenic on PEKK. In vivo results indicated that PEKK seeded with hSF-MSCs regenerated twice the amount of newly formed bone when compared to PEKK seeded with osteogenically-induced hSF-MSCs or PEKK scaffolds alone. These results suggested that there was no need to induce hSF-MSCs into osteoblasts prior to their transplantations in vivo. In conclusion, the combined use of PEKK and hSF-MSCs was effective in regenerating critical-sized bone defects.

Bone extracts immunomodulate and enhance the regenerative performance of dicalcium phosphates bioceramics.

Immunomodulation strategies are believed to improve the integration and clinical performance of synthetic bone substitutes. One potential approach is the modification of biomaterial surface chemistry to mimic bone extracellular matrix (ECM). In this sense, we hypothesized that coating synthetic dicalcium phosphate (DCP) bioceramics with bone ECM proteins would modulate the host immune reactions and improve their regenerative performance. To test this, we evaluated the in vitro proteomic surface interactions and the in vivo performance of ECM-coated bioceramic scaffolds. Our results demonstrated that coating DCP scaffolds with bone extracts, specifically those containing calcium-binding proteins, dramatically modulated their interaction with plasma proteins in vitro, especially those relating to the innate immune response. In vivo, we observed an attenuated inflammatory response against the bioceramic scaffolds and enhanced peri-scaffold new bone formation supported by the increased osteoblastogenesis and reduced osteoclastogenesis. Furthermore, the bone extract rich in calcium-binding proteins can be 3D-printed to produce customized hydrogels with improved regeneration capabilities. In summary, bone extracts containing calcium-binding proteins can enhance the integration of synthetic biomaterials and improve their ability to regenerate bone probably by modulating the host immune reaction. This finding helps understand how bone allografts regenerate bone and opens the door for new advances in tissue engineering and bone regeneration. STATEMENT OF SIGNIFICANCE: Foreign-body reaction is an important determinant of in vivo biomaterial integration, as an undesired host immune response can compromise the performance of an implanted biomaterial. For this reason, applying immunomodulation strategies to enhance biomaterial engraftment is of great interest in the field of regenerative medicine. In this article, we illustrated that coating dicalcium phosphate bioceramic scaffolds with bone-ECM extracts, especially those rich in calcium-binding proteins, is a promising approach to improve their surface proteomic interactions and modulate the immune responses towards such biomaterials in a way that improves their bone regeneration performance. Collectively, the results of this study may provide a conceivable explanation for the mechanisms involved in presenting the excellent regenerative efficacy of natural bone grafts.

Removable partial denture alloys processed by laser-sintering technique.

Removable partial dentures (RPDs) are traditionally made using a casting technique. New additive manufacturing processes based on laser sintering has been developed for quick fabrication of RPDs metal frameworks at low cost. The objective of this study was to characterize the mechanical, physical, and biocompatibility properties of RPD cobalt-chromium (Co-Cr) alloys produced by two laser-sintering systems and compare them to those prepared using traditional casting methods. The laser-sintered Co-Cr alloys were processed by the selective laser-sintering method (SLS) and the direct metal laser-sintering (DMLS) method using the Phenix system (L-1) and EOS system (L-2), respectively. L-1 and L-2 techniques were 8 and 3.5 times more precise than the casting (CC) technique (p < 0.05). Co-Cr alloys processed by L-1 and L-2 showed higher (p < 0.05) hardness (14-19%), yield strength (10-13%), and fatigue resistance (71-72%) compared to CC alloys. This was probably due to their smaller grain size and higher microstructural homogeneity. All Co-Cr alloys exhibited low porosity (2.1-3.3%); however, pore distribution was more homogenous in L-1 and L-2 alloys when compared to CC alloys. Both laser-sintered and cast alloys were biocompatible. In conclusion, laser-sintered alloys are more precise and present better mechanical and fatigue properties than cast alloys for RPDs. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1174-1185, 2018.