Anti-biofilm effect of salivary histatin 5 on Porphyromonas gingivalis.

This study aimed to investigate the effects of salivary histatin 5 (Hst5) on Porphyromonas gingivalis (P. gingivalis) biofilms in vitro and in vivo and the possible mechanisms. In in vitro experiments, P. gingivalis biomass was determined by crystal violet staining. Polymerase chain reaction, scanning electron microscopy, and confocal laser scanning microscopy were used to determine the Hst5 concentration. A search for potential targets was performed using transcriptomic and proteomic analyses. In vivo experimental periodontitis was established in rats to evaluate the effects of Hst5 on periodontal tissues. Experimental results showed that 25 µg/mL Hst5 effectively inhibited biofilm formation, and increased concentrations of Hst5 increased the inhibitive effect. Hst5 might bind to the outer membrane protein RagAB. A combination of transcriptomic and proteomic analyses revealed that Hst5 could regulate membrane function and metabolic processes in P. gingivalis, in which RpoD and FeoB proteins were involved. In the rat periodontitis model, alveolar bone resorption and inflammation levels in periodontal tissues were reduced by 100 µg/mL Hst5. This study showed that 25 µg/mL Hst5 inhibited P. gingivalis biofilm formation in vitro by changing membrane function and metabolic process, and RpoD and FeoB proteins might play important roles in this process. Moreover, 100 µg/mL Hst5 inhibited periodontal inflammation and alveolar bone loss in rat periodontitis via its antibacterial and anti-inflammatory effects. KEY POINTS: • Anti-biofilm activity of histatin 5 on Porphyromonas gingivalis was investigated. • Histatin 5 inhibited Porphyromonas gingivalis biofilm formation. • Histatin 5 showed inhibitory effects on the occurrence of rat periodontitis.

Association between periodontal disease and oral squamous cell carcinoma: a systematic review and meta-analysis.

To investigate the relation between periodontal disease (PD) and oral squamous cell carcinoma (OSCC) we systematically searched records published up to August 2022. Odds ratios (OR) and relative risk (RR) with 95% confidence intervals (95% CI) were estimated to evaluate this relation, then sensitivity analysis was performed accordingly. Begg's test and Egger's test were used to detect publication bias. Out of 970 papers from several databases, 13 studies were included. Summary estimates showed that PD was positively associated with the prevalence of OSCC (OR = 3.28, 95% CI: 1.87 to 5.74), especially for severe PD (OR = 4.23, 95% CI: 2.92 to 6.13). No evident publication bias was revealed. No increased OSCC risk among patients with PD was shown according to the combined results (RR = 1.50, 95% CI: 0.93 to 2.42). Patients with OSCC exhibited significant differences in alveolar bone loss, clinical attachment loss, and bleeding on probing, when compared with controls. The systematic review and meta-analysis suggested that there was a positive association between PD and prevalence of OSCC. However, according to the current evidence, a causal relation is unclear.

Zinc-coated carbonate apatite derived from avian eggshell for potential use as bone substitute. Part I: preparation and properties.

PURPOSE: To develop antibacterial bone substitutes derived from avian eggshell using microwave processing to convert natural calcium carbonate (CaCO3) into zinc-coated carbonate apatite (CHA). METHODS: Zinc-coated carbonate apatite was prepared using domestic microwave and then characterized with scanning electron microscopy (SEM), x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and energy dispersive x-ray analysis (EDXA). The trial animal study was conducted by filling different bone substitutes into 5-mm-diameter standard defects on the parietal bone of New Zealand rabbits to observe new bone formation for 8 weeks. RESULTS: SEM, XRD, FT-IR, and EDXA confirmed characteristics of zinc-coated CHA derived from avian eggshell using microwave method. Histological analysis demonstrated that the defects filled with carbonate apatite had more calcified bone and less uncalcified bone formation than other groups. CONCLUSIONS: The present research demonstrated the efficient use of microwave in the conversion of natural CaCO3 into CHA with zinc coating. The examined properties showed the potential use of the new material as an antibacterial bone substitute in oral surgery. The trial animal study implied favorable osteoconductive ability of carbonate apatite in new bone formation.

Ultrahigh Efficiency and Minimalist Intracellular Delivery of Macromolecules Mediated by Latent-Photothermal Surfaces.

Intracellular delivery of exogenous macromolecules by photothermal methods is still not widely employed despite its universal and clear effect on cell membrane rupture. The main causes are the unsatisfactory delivery efficiency, poor cell activity, poor cell harvest, and sophisticated operation; these challenges stem from the difficulty of simply controlling laser hotspots. Here, we constructed latent-photothermal surfaces based on multiwall carbon nanotube-doped poly(dimethyl siloxane), which can deliver cargoes with high delivery efficiency and cell viability. Also, cell release and harvest efficiencies were not affected by coordinating the hotspot content and surface structure. This system is suitable for use with a wide range of cell lines, including hard-to-transfect types. The delivery efficiency and cell viability were shown to be greater than 85 and 80%, respectively, and the cell release and harvest efficiency were greater than 95 and 80%, respectively. Moreover, this system has potential application prospects in the field of cell therapy, including stem cell neural differentiation and dendritic cell vaccines.

Microbiota in Human Periodontal Abscess Revealed by 16S rDNA Sequencing.

Periodontal abscess is an oral infective disease caused by various kinds of bacteria. We aimed to characterize the microbiota composition of periodontal abscesses by metagenomic methods and compare it to that of the corresponding pocket and healthy gingival crevice to investigate the specific bacteria associated with this disease. Samples from abscess pus (AB), periodontal pocket coronally above the abscess (PO), and the gingival crevice of the periodontal healthy tooth were obtained from 20 periodontal abscess patients. Furthermore, healthy gingival crevice samples were obtained from 25 healthy individuals. Bacterial DNA was extracted and 16S rRNA gene fragments were sequenced to characterize the microbiota and determine taxonomic classification. The beta-diversity analysis results showed that the AB and PO groups had similar compositions. Porphyromonas gingivalis, Prevotella intermedia, and other Prevotella spp. were the predominant bacteria of human periodontal abscesses. The abundances of Filifactor alocis and Atopobium rimae were significantly higher in periodontal abscesses than in the periodontal pocket, suggesting their association with periodontal abscess formation. In conclusion, we characterized the microbiota in periodontal abscess and identified some species that are positively associated with this disease. This provides a better understanding of the components of periodontal abscesses, which will help facilitate the development of antibiotic therapy strategies.

16S rDNA analysis of periodontal plaque in chronic obstructive pulmonary disease and periodontitis patients.

This study investigated if chronic obstructive pulmonary disease (COPD) is correlated with periodontitis via periodontal microbiota and if certain bacteria affect periodontitis as well as COPD. Moreover, the study investigated whether suffering from COPD is associated with a decrease in the richness and diversity of periodontal microbiota. Subgingival plaque was obtained from 105 patients. Bacterial DNA was isolated from 55 COPD and 50 non-COPD participants (either with or without periodontitis). 16S rRNA gene metagenomic sequencing was used to characterize the microbiota and to determine taxonomic classification. In the non-periodontitis patients, suffering from COPD resulted in a decrease in bacteria richness and diversity in the periodontal microenvironment. An increase in the genera Dysgonomonas, Desulfobulbus, and Catonella and in four species (Porphyromonas endodontalis, Dysgonomonas wimpennyi, Catonella morbi, and Prevotella intermedia) in both COPD and periodontitis patients suggests that an increase in these periodontitis-associated microbiota may be related to COPD. Three genera (Johnsonella, Campylobacter, and Oribacterium) were associated with COPD but not with periodontitis. The decrease in the genera Arcanobacterium, Oribacterium, and Streptomyces in COPD patients implies that these genera may be health-associated genera, and the decrease in these genera may be related to disease. These data support the hypothesis that COPD is correlated with periodontitis via these significantly changed specific bacteria.

A comparative analysis of metal allergens associated with dental alloy prostheses and the expression of HLA-DR in gingival tissue.

The present study aimed to provide guidance for the selection of prosthodontic materials and the management of patients with a suspected metal allergy. This included a comparison of the sensitivity of patients to alloys used in prescribed metal­containing prostheses, and correlation analysis between metal allergy and accompanying clinical symptoms of sensitized patients using a patch test. The results from the patch test and metal component analyses were processed to reach a final diagnosis. In the present study, four dental alloys were assessed. Subsequent to polishing the surface of a metal restoration, the components were analyzed using an X­ray fluorescence microscopy and spectrometry. Immunohistochemical analysis, reverse transcription­polymerase chain reaction and western blotting were used to detect the expression levels of human leukocyte antigen (HLA)­DR in gingival tissues affected by alloy restoration, and in normal gingival tissue samples. Positive allergens identified in the patch test were consistent with the components of the metal prostheses. The prevalence of nickel (Ni) allergy was highest (22.8%), and women were significantly more allergic to palladium and Ni than men (P<0.05). The protein and gene expression levels of HLA­DR in the Ni­chromium (Cr) prosthesis group were significantly higher, compared with those in the other groups (P<0.01); followed by cobalt­Cr alloy, gold alloy and titanium alloy. In conclusion, dentists require an understanding of the corrosion and allergy rates of prescribed alloys, in order to reduce the risk of allergic reactions. Patch testing for hypersensitive patients is recommended and caution is required when planning to use different alloys in the mouth.

Intra-Genomic Heterogeneity in 16S rRNA Genes in Strictly Anaerobic Clinical Isolates from Periodontal Abscesses.

BACKGROUND: Members of the genera Prevotella, Veillonella and Fusobacterium are the predominant culturable obligate anaerobic bacteria isolated from periodontal abscesses. When determining the cumulative number of clinical anaerobic isolates from periodontal abscesses, ambiguous or overlapping signals were frequently encountered in 16S rRNA gene sequencing chromatograms, resulting in ambiguous identifications. With the exception of the genus Veillonella, the high intra-chromosomal heterogeneity of rrs genes has not been reported. METHODS: The 16S rRNA genes of 138 clinical, strictly anaerobic isolates and one reference strain were directly sequenced, and the chromatograms were carefully examined. Gene cloning was performed for 22 typical isolates with doublet sequencing signals for the 16S rRNA genes, and four copies of the rrs-ITS genes of 9 Prevotella intermedia isolates were separately amplified by PCR, sequenced and compared. Five conserved housekeeping genes, hsp60, recA, dnaJ, gyrB1 and rpoB from 89 clinical isolates of Prevotella were also amplified by PCR and sequenced for identification and phylogenetic analysis along with 18 Prevotella reference strains. RESULTS: Heterogeneity of 16S rRNA genes was apparent in clinical, strictly anaerobic oral bacteria, particularly in the genera Prevotella and Veillonella. One hundred out of 138 anaerobic strains (72%) had intragenomic nucleotide polymorphisms (SNPs) in multiple locations, and 13 strains (9.4%) had intragenomic insertions or deletions in the 16S rRNA gene. In the genera Prevotella and Veillonella, 75% (67/89) and 100% (19/19) of the strains had SNPs in the 16S rRNA gene, respectively. Gene cloning and separate amplifications of four copies of the rrs-ITS genes confirmed that 2 to 4 heterogeneous 16S rRNA copies existed. CONCLUSION: Sequence alignment of five housekeeping genes revealed that intra-species nucleotide similarities were very high in the genera Prevotella, ranging from 94.3-100%. However, the inter-species similarities were relatively low, ranging from 68.7-97.9%. The housekeeping genes rpoB and gyrB1 were demonstrated to be alternative classification markers to the species level based on intra- and inter-species comparisons, whereas based on phylogenetic tree rpoB proved to be reliable phylogenetic marker for the genus Prevotella.

Antimicrobial resistance and prevalence of resistance genes of obligate anaerobes isolated from periodontal abscesses.

BACKGROUND: This study attempts to determine the antimicrobial resistance profiles of obligate anaerobic bacteria that were isolated from a periodontal abscess and to evaluate the prevalence of resistance genes in these bacteria. METHODS: Forty-one periodontal abscess samples were cultivated on selective and non-selective culture media to isolate the oral anaerobes. Their antibiotic susceptibilities to clindamycin, doxycycline, amoxicillin, imipenem, cefradine, cefixime, roxithromycin, and metronidazole were determined using the agar dilution method, and polymerase chain reaction assays were performed to detect the presence of the ermF, tetQ, nim, and cfxA drug resistance genes. RESULTS: A total of 60 different bacterial colonies was isolated and identified. All of the isolates were sensitive to imipenem. Of the strains, 6.7%, 13.3%, 16.7%, and 25% were resistant to doxycycline, metronidazole, cefixime, and amoxicillin, respectively. The resistance rate for both clindamycin and roxithromycin was 31.7%. Approximately 60.7% of the strains had the ermF gene, and 53.3% of the amoxicillin-resistant strains were found to have the cfxA gene. Two nim genes that were found in eight metronidazole-resistant strains were identified as nimB. CONCLUSIONS: In the present study, the Prevotella species are the most frequently isolated obligate anaerobes from periodontal abscesses. The current results show their alarmingly high resistance rate against clindamycin and roxithromycin; thus, the use of these antibiotics is unacceptable for the empirical therapy of periodontal abscesses. A brief prevalence of four resistance genes in the anaerobic bacteria that were isolated was also demonstrated.

[Detection of anaerobes and drug sensitivity from the periodontal pockets of patients with combined periodontal-endodontic lesions].

PURPOSE: To investigate the correlation between the composition of bacterial flora isolated from deep periodontal pockets with combined periodontal-endodontic lesions, and to test the antibiotic susceptibility of anaerobes. METHODS: Microbial samples were taken from 82 deep periodontal pockets with combined periodontal-endodontic lesions using adequate techniques, and divided into two groups: endo-perio group and perio-endo group. Antibiotic susceptibility of cultivable anaerobes were tested with agar dilution method. RESULTS: Eighty-six cultivable anaerobes were isolated, including Streptococcus spp, Prevotella spp, Actinomycetes spp, Veillonella spp, Fusobacterium spp and etc. 53.4% were gram-positive anaerobes, while 46.51% were gram-negative anaerobes. The detection rate of anaerobes in endo-perio group and that in perio-endo group had significant difference. Most isolated anaerobes were sensitive to six drugs. The resistance rates of penicillin, clindamycin, metronidazole were 6.8%, 13.9% and 2.2%. CONCLUSIONS: There is a close relationship between anaerobes and combined periodontal-endodontic lesions. Drug sensitive susceptibility should be detected prior to clinical treatment of combined periodontal-endodontic lesions.

[Distribution of anaerobes in periodontal abscess and its resistance to antibiotics].

OBJECTIVE: To isolate and culture the predominant anaerobes from the periodontal abscesses, and to test the antibiotic susceptibility and drug resistant genes of the strains. METHODS: The isolated strains were identified by both API20A biochemical method and polymerase chain reaction (PCR) method. The antibiotic susceptibility test was performed by agar dilution method. The resistant genes of the drug-resistant strains obtained were screened by PCR. RESULTS: The anaerobes were detected in 48% (28/58) of the samples and Prevotella melaninogenica (Pm) was mostly identified in 43% (12/28). API20A biochemical method had 82% (23/28) agreement with the 16SrRNA method in identification rate. Anaerobes were resistant to metronidazole, clindamycin and cefmetazole. The erythromycin-resistant methylase genes F (ermF) gene was detected in three of eight clindamycin resistant strains. None of them was found coded on bacterial plasmids. However, no metronidazole resistant gene was detected on drug resistant strains. CONCLUSIONS: Pm was the predominant species dectected in the periodontal abscess of the patients. The antibiotic agents should be used based on the genotypes and general condition of the patients.

[The effect of adiponectin on human periodontal ligament fibroblasts in vitro].

PURPOSE: To investigate the expression of adiponectin receptor in periodontal tissues and the effect of adiponectin with different concentrations on the proliferation of human periodontal ligament fibroblast cells. METHODS: Ten human healthy premolars extracted for orthodontic reasons were collected. The primary cells were isolated from human periodontal ligament and cultured by tissue block method,then passaged when the cells completely covered the bottom of petri dish. The expression of AdipoR1 and AdipoR2 in human periodontal ligament fibroblasts was detected by RT-PCR. Adiponectin (0,5,10,20ng/µL) was added to petri dish in which the cells were incubated for 24 hours.The cells were then incubated with adiponectin for 7 days,and determined by MTT assay.SPSS16.0 software package was used for statistical analysis. RESULTS: By immunocytochemical method,the cells were stained positively to antibodies against vimentin,and negatively to antibodies against cytokeratin,indicating that they were external embryo mesenchymal cells ,without epithelial cell mixation. Agarose gel electrophoresis showed Adipo R2 was positively expressed in human periodontal ligament fibroblasts. MTT assay showed that proper doses of adiponectin could promote proliferation of human periodontal ligament fibroblasts (P<0.05).The number of adherent cells of group C or group D was significantly greater than that of group A after 24 hours(P<0.05); Group B, group C,and group D had significantly more adherent cells than group A after 96 hours and 168 hours (P<0.05). CONCLUSIONS: Adiponectin receptor 2 is expressed in the periodontal tissues.The proper doses of adiponectin could promote proliferation of human periodontal ligament fibroblasts.

[Jaw bone density assessments of implant sites using spiral CT and Simplant software].

PURPOSE: To assess the bone density of dental implant sites using spiral CT and simplant software, and classify them by Lekholm and Zarb grouping. METHODS: 53 patients' jaw bone were scanned by spiral CT, the scanned images were reconstructed by the Simplant software.The bone density of 136 designed implant sites was measured and the results were recorded using Hounsfield units(HU).The data was analyzed with SPSS11.0 software package for Mann-Whitney U test, and classified by Lekholm and Zarb grouping. RESULTS: The mean bone density in all implant sites was (714.66+/-273.72) HU.The anterior mandible mean bone density was (962.96+/-92.21)HU>anterior maxilla, (786.15+/-188.74) HU>posterior mandible, (785.79+/-290.91) HU>posterior maxilla, (569.67+/-244.34)HU. Bone class IV was least in anterior mandible and most in posterior maxilla(P<0.01), accounting for 26.5% in all implant sites. CONCLUSIONS: Anterior mandible has the highest mean bone density and posterior maxilla has the lowest mean bone density. There are class I and II/III in most of the implant sites. Spiral CT is a useful tool for determining the bone density, which is important for preoperative design and postoperative assessment.

[Application of the bone quality of pre-implanted mandible through optical density measurement].

PURPOSE: To assess the bone quality of the pre-implanted mandible through an approach of the optical density after examination of the pantomography and analyze the feasibility. METHODS: Thirty males and 30 females who underwent the procedure of dental implantation were examined with the pantomography and CT scan before the procedure. The films were scanned into computerized bitmap files. Four areas of interest were selected. The mandibular angle, the posterior part of the mandibular body, the anterior part of the mandibular body and the pre-implanted area. The mean optical densities of these four areas were measured with the software ImagePro Plus. The mean optical densities of the pre-implanted area of three groups underwent Kruskal-Wallis test and LSD-t test. Then the CT values of these four areas were measured with the software SimPlant after data importation. The liner correlation analysis was carried out between the mean optical densities and CT values for the four areas of interest. RESULTS: The mean optical density of the pre-implant area was lower than that of the mandibular angle and the posterior part of the mandible body. There were significant differences between the means of optical density of the pre-implanted regions of different groups. There was a liner correlation between the optical densities and CT values of the same areas of interest. CONCLUSIONS: The approach of optical density analysis is able to classify the different divisions of mandible and its results bear the same fidelity with the SimPlant with CT scan. This approach is effective and feasible.

[Three dimensional finite element stress analysis in the vertical fractured first premolar after bonding and replantation].

PURPOSE: To evaluate the change of stress distribution after bonding and replantation of vertical fractured first maxillary premolar. METHODS: The stress distribution in two types of loading and different treatments on the vertical fractured first maxillary premolar were analyzed by three dimensional finite element. The gap was respectively filled with Clearfil SE Bond and Super Bond C & B; and vertical and lateral stress force was calculated. RESULTS: The result of the FEM study of adhesive fracture tooth indicated that the stress distribution was similar to the normal tooth, Clearfil SE Bond was better than Super Bond C & B. CONCLUSION: The treatment of bonding and replantation for vertical fractured tooth is effective.

Treatment of combined endodontic-periodontic lesions by intentional replantation and application of hydroxyapatites.

A case of combined endodontic-periodontic lesions on a mandibular first molar was treated by intentional replantation and application of hydroxyapatites. Four months after the surgery, a porcelain-mental full crown restoration was completed. The 15-month follow-up examination showed that the tooth was clinically and radiographically healthy and functioned well.