Narrow Results

We evaluated the effects of paeonol, a phenolic compound of Moutan Cortex, on the tissue inflammation and destruction in experimental periodontitis of rats. The maxillary palatal bony surfaces of 18 rats received injections of lipopolysaccharide (LPS, 5 mg/mL), PBS or LPS-plus-paeonol (40 mg/kg, intra-peritoneal injection) for three days. Five days later, the osteoclasts were examined and compared after tartrate-resistant acid phosphatase staining. In another 36 rats, the experimental periodontitis was induced by placing the ligatures around the maxillary second and mandibular first molars. Seven days later, the periodontal destruction and inflammation in rats with paeonol (40 mg/kg or 80 mg/kg) and those who had no ligature or without paeonol were compared by dental radiography, micro-computerized tomography (micro-CT), and histology. Gingival mRNA expressions of pre-inflammatory cytokines, including IL-1β' IL-6 and TNF-α were also examined. Compared to the effect of the LPS positive control, the paeonol injection significantly reduced the induced osteoclast formation. In ligature-induced periodontitis, the periodontal bone supporting ratio was significantly higher in the ligature-plus-paeonol groups compared to that of the ligature group, although they were still less than those in the non-ligature group. By micro-CT and by histology/histometry, a consistent anti-destructive effect was observed when paeonol was added. Moreover, less amount of inflammatory cell-infiltrated connective tissue area, connective tissue attachment, and mRNA expressions of pro-inflammatory cytokines were presented in the ligature-plus-paeonol groups than those in the ligature group. These results suggested that paeonol might have a protective potential on gingival tissue inflammation and alveolar bone loss during the process of periodontitis by inhibiting pro-inflammatory cytokines.

Cellular automata (CA) are time and space discrete dynamical systems that can model biological systems. The aim of this study is to simulate by CA experiments how the disease of periodontitis propagates along the dental root surface. Using a Moore neighborhood on a grid copy of the pattern of periodontal ligament fibers (PDLF) supporting and anchoring the teeth to bone, we investigate the fractal structure of the associated pattern using all possible outer-totalistic CA rules. On the basis of the propagation patterns, CA rules are classified in three groups, according to whether the disease was spreading, remaining constant or receding. These are subsequently introduced in a finite state Markov model as probabilistic "state-rules" and the model is validated using datasets retrieved from previous studies.

Based on the maximum entropy production principle, we identified the "state-rule" that most appropriately describes the PDLF pattern, showing a power law distribution of periodontitis propagation rates with exponent 1.3. Entropy rates and mutual information of Markov chains were estimated by extensive data simulation. The scale factor of the PDLF used to estimate the conditional entropy of Markov chains was seen to be nearly equal 1.85. This possibly reflects the fact that a dataset representing tooth percentage with bone loss equal to 50% or more of their root length, is found to have a fractal dimension (FD) of about 1.84. Similarly, datasets of serum neutrophil, basophil, eosinophil, monocyte counts and IgG, IgA, IgM levels taken from periodontitis patients, showed a FD ranging from 1.82 to 1.87.

Our study presents the first mathematical model to our knowledge that suggests periodontitis is a nonlinear dynamical process. Moreover, the model we propose implies that the entropy rate of the immune-inflammatory host response dictates the rate of periodontitis progression. This is validated by clinical data and suggests that our model can serve as a basis for detecting periodontitis susceptible individuals and shaping prognosis for treated periodontitis patients.

We conducted a longitudinal study involving $240$ patients grouped according to the classification of periodontal diseases agreed in the World Workshop by the different groups of specialists gathered there. We proceed to select images of Cone Beam Computed Tomography (CBCT) that were used to perform a study of bone density through a precise algorithm allowing an accurate calculation of the fractal dimensions of such images. A detailed anthropometric analysis was also carried out. Our objective was to demonstrate that there exists a direct relationship between either the loss of bone or the changes related to its height and diameter and the variations in bone density. Our results highlight significant differences among the initial and moderate periodontal groups with respect to both the control and the periodontal groups, where patients experience a severe and controlled periodontal disease. We conclude that there is a variation in the architecture of patients with periodontal disease that have an acute component and have not been treated or their treatment is not effective and their bone loss does not slow down.

Adding value through additive dentistry

Dental care for the silver generation

Digitising Dentistry

Dental dangers – Poor oral health and NCDs

In the last decades the worldwide rise in antibiotic resistance has intensified the development of new antimicrobial agents. Photodynamic antimicrobial chemotherapy (PACT) has been used successfully to inactivate bacteria. We herein report a new zinc phthalocyanine based photosensitizer conjugated with polylysine moiety (ZnPc-PL). This photosensitizer significantly inactivated Porphyromonas gingivalis, the primary pathogenic bacteria responsible for periodontitis. No obvious phototoxicity was found to either mammalian bone marrow stromal cells (BMSC) or human periodontal ligament cells (HPDLC), indicating the high selectivity of ZnPc-PL toward bacteria. Furthermore, we established an experimental periodontitis model on beagle dogs to test the antimicrobial efficacy in vivo. The amount of gingival crevicular fluid (GCF) and the activity of crevicular fluid aspartate aminotransferase (AST) were monitored and were found to reduce significantly in the ZnPc-PL treated group compared to the controls (laser only and no treatment). In addition, PACT with ZnPc-PL caused a reduction in the bacterial burden by 100-fold compared to controls. Taken together, these findings suggest ZnPc-PL is a promising antimicrobial photosensitizer for the treatment of periodontal diseases.

Photodynamic therapy (PDT) has been commonly used in treating many diseases, such as cancer and infectious diseases. We investigated the different effects of PDT on three main pathogenic bacteria of periodontitis — Prevotella melaninogenica (P.m.), Porphyromonas gingivalis (P.g.) and Aggregatibacter actinomycetemcomitans (A.a.). The portable red light-emitting diode (LED) phototherapy device was used to assess the exogenous PDT effects with different light doses and photosensitizer concentrations (Toluidine blue O, TBO). The portable blue LED phototherapy device was used to assess the endogenous PDT effects with the use of endogenous photosensitizers (porphyrin) under different light doses. We found out that both exogenous and endogenous PDT were able to restrict the growth of all the three bacteria significantly. Moreover, the optimal PDT conditions for these bacteria were obtained through this in vitro screening and could guide the clinical PDT on periodontitis.