Effect of P. gingivalis supernatant and Kavain on bone biology

P. gingivalis, a red complex bacterium, has been associated with periodontitis. It has been studied extensively trying to understand the mechanism behind its virulence against the periodontium. Several investigations have studied the different virulence factors including Lipopolysaccharide (LPS), gingipain and fembriea. However, bone resorption mechanism that is caused by periodontitis is not fully understood. It is hypothesized that P. gingivalis virulence factors specifically LPS are behind bone resorption, not the bacterial cell itself. Therefore, we have tested this hypothesis and then further expanded on the results by adding Kavain that inhibit LPS-induced TNF-α in an attempt to rule out other virulence factor from bone resorption mechanism. Live neonatal mouse calvarial bone was utilized to carry out experiments in this project. We had five groups which included negative and positive control with parathyroid hormone (PTH) and PTH with Kavain and test groups with P. gingivalis supernatant with or without Kavain. These model systems were tested under resorption condition and evaluated by chemical, biochemical and histological analyses of the used media and calvarial bone. At the 8th day, calvaria from each experiments were analyzed by histology. TRAP and calcium release assays were also performed to further evaluate bone resorption and osteoclastic activity. We have found that when Kavain was added to the PTH, the calcium release and TRAP activity has reduced to half of the positive control without Kavain. P gingivalis supernatant alone showed uptake of calcium rather than release and adding Kavain increased the calcium uptake even more. However, TRAP activity were much higher than PTH group which does not coincide with the calcium release assay results. It seems that P. gingivalis LPS stimulated osteoclastic activity however it was not enough to result in bone resorption. It is thought that resorption and formation might be balanced and thus resorption was not observed. Further investigation is needed to study different doses of P. gingivalis supernatant on bone

Accuracy of Schneiderian membrane thickness: a coneâ beam computed tomography analysis with histological validation

ObjectivesConeâ beam computed tomography (CBCT) has been used in the literature to evaluate Schneiderian membrane thickness (SMT), but its accuracy has never been validated. The primary aim of this study was to compare the SMT measured by CBCT to the gold standard histological assessment. The correlations between SMT and anatomical structures of the maxillary sinus and alveolar bone were also tested.Materials and MethodsFourteen fresh cadaver heads were used for the study, and 28 sinus lift augmentation procedures were performed to obtain the membrane samples. Samples were fixed in formalin and stained with hematoxylinâ eosine and Masson trichrome. Specimens were measured by optic microscope at three points, and a mean was obtained. Anatomical landmarks were used to accurately position the CBCT slice, so the SMT could be measured in predetermined locations. Wilcoxon signedâ rank test was used to compare values of histological and CBCT measurements, and Spearman’s correlation coefficient was calculated to examine the relationship between thickness and anatomical parameters.ResultsA total of 597 histological measurements were performed, and the mean SMT thickness was 0.30 ± 0.17 mm. The mean CBCT membrane thickness was 0.79 ± 0.52 mm. A statistically significant difference from histological and radiological readings was observed (P = 0.000). Interestingly, 87.77% histological measurements had membrane less than 0.5 mm in thickness compared to 26.66% in CBCT assessment.ConclusionsWithin the limitation of this study, the median histological Schneiderian membrane thickness was 0.30 mm. Coneâ beam computed tomography assessment was 2.6 times higher than the histological examination.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137465/1/clr12856_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137465/2/clr12856.pd

The Effect of Locally Delivered Statins on Treating Periodontal Intrabony Defects: A Systematic Review and Metaâ Analysis

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142319/1/jper0357.pd