A p38 mitogen-activated protein kinase inhibitor arrests active alveolar bone loss in a rat periodontitis model

BACKGROUND: Gram-negative bacterial species, such as Actinobacillus actinomycetemcomitans, contain lipopolysaccharide (LPS) that initiates the innate immune system, resulting in inflammatory alveolar bone loss. LPS activates Toll-like receptors on membrane surfaces, stimulating many intracellular signaling cascades, including the p38 mitogen-activated protein kinase (MAPK). Activation of p38 signaling mediates inflammatory cytokine expression, contributing toward osteoclastogenesis and bone loss. The aim of this study was to determine whether the novel, orally active p38 MAPK inhibitor SD282 could arrest progression of LPS-induced alveolar bone destruction in rats. METHODS: Three groups of female Sprague-Dawley rats received LPS injections to the palatal molar gingiva three times per week for 4 weeks to establish periodontitis. From weeks 5 through 8, two groups received the drug SD282 (N = 14) or 1% polyethylene glycol drug vehicle (N = 14) via oral gavage in addition to LPS injections. The third group continued to receive only LPS injections (N = 8). Microcomputed tomography was used to measure volumetric alveolar bone loss, expressed as bone volume fraction (BVF). Expression of interleukin (IL)-1 and -6 and tumor necrosis factor-alpha (TNF-alpha) was assessed by immunohistochemistry, and osteoclasts were enumerated by tartrate-resistant acid phosphatase staining. RESULTS: By 4 weeks, severe alveolar bone resorption was seen in LPS-injected animals. Administration of SD282 significantly blocked additional volumetric bone loss in the LPS-only versus LPS + SD282 groups (0.37 +/- 0.01 BVF versus 0.43 +/- 0.01 BVF; P < 0.01). Significant reductions in IL-1beta (P < 0.01 ), TNF-alpha (P < 0.05), and osteoclast formation (P < 0.01) occurred in the presence of SD282. CONCLUSIONS: An orally active p38 MAPK inhibitor reduced LPS-induced inflammatory cytokine expression, osteoclastogenesis, and alveolar bone loss in rats. Within the limits of the current study, SD282 arrested periodontal disease progression, thus highlighting the therapeutic potential of this novel class of inhibitors.     

Senior house officer training in oral and maxillofacial surgery: a national survey

Service commitments have often taken priority over training for many senior house officers. There have been changes, with more planned to make this truly a training grade. We conducted a national postal survey of senior house officers (SHO) in oral and maxillofacial surgery (OMFS) in 2001/2002. A total of 229 replies were received with an estimated response rate around 70%. Almost 60% of these respondents (57.2%) had been a SHO in OMFS for over 3 years. Only 39% had a weekly bleep-free teaching session. Forty-eight per cent did not think undergraduate BDS training was adequate for their job. This 48% of SHOs were significantly less likely to have out patient clinic sessions with a designated trainer undertaking teaching (chi 2 = 6.127, P = 0.013) or have a bleep-free teaching session (chi 2 = 6.896, P = 0.009). Sixty-four per cent had received formal training in medical examination of patients. Twenty-nine per cent had not been appraised during their present post. Forty-two per cent of SHOs in OMFS are in band 3 posts. Improvements have been made, but there is a case for further change.     

An in vitro evaluation of the contents of root canals obturated with gutta percha and AH-26 sealer or Resilon and Epiphany sealer

The purpose of this study was to compare the contents of root canals obturated with gutta percha and AH-26 sealer (Dentsply, Tulsa, OK) to canals obturated with the Resilon and Epiphany (Pentron, Wallingford, CT) system. Canal contents were assessed by determining the percentage of canal space occupied by core material, sealer, voids, and debris. Forty extracted human maxillary anterior teeth were instrumented, and the teeth were randomly assigned to either the gutta percha/AH 26 group or the Epiphany/Resilon group. Canals were obturated, and the teeth were subsequently embedded in resin and sectioned horizontally at 2, 4, and 6 mm from the anatomic apex. Sections were photographed by using a low vacuum scanning electron microscope. Image-J (Wayne Rasband; National Institute of Health, Bethesda, MD) software was used to quantify the proportion of core material, sealer, voids, and debris in each canal. Percentages and statistical comparisons for each method were compared. There were no significant differences found among the two groups in terms of the percentage of core (p = 0.9), sealer (p = 0.58), debris (p = 0.999), or voids (p = 1.00). Additionally, there were no differences in the percentage of core material, sealer, debris, or voids at any of the examined levels (2, 4, or 6 mm).     

Processed bovine dentine as a bone substitute

OBJECTIVES: Different forms of allogenic dentine have been studied for their potential use as bone substitutes. We report a new method for processing bovine dentine that results in a sterile bioactive material for repair and regeneration of bone. METHODS: Extracted bovine dentine was processed mechanically and chemically with inorganic and organic solvents, and sterilised. The in vitro biocompatibility on human gingival fibroblasts was assessed by the Alamar Blue assay and the in vivo biocompatibility evaluated by implantation of the processed dentine into rats' femurs. RESULTS: The dentine showed excellent biocompatibility in vitro, stimulated formation of new bone and was completely incorporated into the new bone in vivo. SIGNIFICANCE: Processed bovine dentine has the potential to be used as a suitable substitute in bone repair and regeneration.     

The effects of viscoelastic parameters on residual stress development in a zirconia/glass bilayer dental ceramic.

OBJECTIVES: The aim of this study was to test the hypothesis that the residual stresses in a zirconia-based bilayer dental composite system can be tailored through heat treatment above and below the glass transition temperature of glass veneers. METHODS: Ceramic bilayer disc specimens were prepared from a zirconia core and a glass veneer. Each bilayer ceramic group was heat treated 40 degrees C below, 20 degrees C and 40 degrees C above and at the glass transition temperature of the glass veneer, and cooled using a fast or a slow cooling rate. Specimens were tested for flexure strength using a biaxial bending fixture. Residual stresses were calculated using a fracture mechanics approach. RESULTS: Heat treatments produced significant differences (p < or =0.05) between the mean flexural strengths of the heat treatment groups when the specimens were cooled using a fast cooling rate. However, there was not a significant difference (p >0.05) between the mean flexural strengths of the heat treatment groups when a slow cooling rate was used. Fractures initiated from the veneer surfaces of the specimens. SIGNIFICANCE: Heat treatment above and below the glass transition temperature of the veneer layer, and the cooling rate have a significant effect on the flexural strength of the bilayer ceramic laminates. The existence of residual compressive stress is the most likely reason for the observed strength increases. Residual stresses can be modified using the elastic-viscoelastic relaxation behavior of a glass veneer.     

The Effects of Bariatric Surgery on Colorectal Cancer Risk: Systematic Review and Meta-analysis

Obesity is an established risk factor for colorectal cancer (CRC) but the effects of bariatric surgery on CRC incidence are uncertain. A systematic review of six electronic databases identified 3691 articles. Four observational studies met our inclusion criteria and results were pooled using a random effects model. Meta-analysis of these four studies revealed that bariatric surgery was associated with a significantly (p?=?0.004) lower CRC incidence (RR?=?0.73, 95 % confidence interval, 0.58–0.90) when compared with obese non-operated individuals, i.e., bariatric surgery is associated with a 27 % lower CRC risk. However the evidence base is limited and these findings should be confirmed by future studies with improved designs.