The effect of bovine trypsin on dental biofilm dispersion: an in vitro study.

To investigate the degradation effect of bovine trypsin on multispecies biofilm of caries-related bacteria and provide an experimental foundation for the prevention of dental caries. Standard strains of S. mutans, S. sanguis, S. gordonii, and L. acidophilus were co-cultured to form 24 h, 48 h, and 72 h biofilms. The experimental groups were treated with bovine trypsin for 30 s, 1 min, and 3 min. Morphological observation and quantitative analysis of extracellular polymeric substances (EPS), live bacteria, and dead bacteria were conducted using the confocal laser scanning microscope (CLSM). The morphological changes of EPS and bacteria were also observed using a scanning electron microscope (SEM). When biofilm was treated for 1 min, the minimal inhibitory concentration (MIC) of bovine trypsin to reduce EPS was 0.5 mg/mL in 24 h and 48 h biofilms, and the MIC of bovine trypsin was 2.5 mg/mL in 72 h biofilms (P < 0.05). When biofilm was treated for 3 min, the MIC of bovine trypsin to reduce EPS was 0.25 mg/mL in 24 h and 48 h biofilms, the MIC of bovine trypsin was 1 mg/mL in 72 h biofilm (P < 0.05). The ratio of live-to-dead bacteria in the treatment group was significantly lower than blank group in 24 h, 48 h, and 72 h multispecies biofilms (P < 0.05). Bovine trypsin can destroy multispecies biofilm structure, disperse biofilm and bacteria flora, and reduce the EPS and bacterial biomass in vitro, which are positively correlated with the application time and concentration.

The Effect of Bovine Trypsin on the Adhesion and pH of Dental Plaque Biofilms: An In Vitro Study.

OBJECTIVE: The aim of this study was to investigate the effect of bovine trypsin on the adhesion and pH of dental plaque biofilms. METHODS: A multispecies dental plaque biofilm model and a single-species dental plaque biofilm model were established in vitro. Three groups were tested: (1) blank control group (aseptic ultrapure water); (2) negative control group (1M Tris-HCl buffer, pH = 7.4); and (3) experimental group (bovine trypsin). Adhesion ability was measured using an automatic microplate reader and visualised by confocal laser scanning microscopy (CLSM). The pH was measured using a pH meter. The expression of gtfB, gtfC, and gtfD was analysed using quantitative real-time polymerase chain reaction. RESULTS: Adhesion ability in the experimental group was significantly lower than that in the blank group and the negative control group (P < .05); readhesion ability in the experimental group was inhibited for a certain period of time (24-hour multispecies biofilms were inhibited from 4 to 8 hours, and the 48- and 72-hour multispecies biofilms were inhibited from 2 to 6 hours; P < .05). The decrease in pH was inhibited for a certain period of time (24-hour multispecies biofilms were inhibited from 2 to 8 hours, and the 48- and 72-hour multispecies biofilms were inhibited from 1 to 8 hours; P < .05). Expression levels of gtfB, gtfC, gtfD, and ldh in the experimental group were significantly lower than those in the blank group (P < .05). CONCLUSIONS: Bacterial adhesion, and readhesion, decreasd pH, and expression of adhesion- and acid-related genes by Streptococcus mutans in biofilms could be reduced by bovine trypsin for a certain period of time.

Expert consensus on irrigation and intracanal medication in root canal therapy.

Chemical cleaning and disinfection are crucial steps for eliminating infection in root canal treatment. However, irrigant selection or irrigation procedures are far from clear. The vapor lock effect in the apical region has yet to be solved, impeding irrigation efficacy and resulting in residual infections and compromised treatment outcomes. Additionally, ambiguous clinical indications for root canal medication and non-standardized dressing protocols must be clarified. Inappropriate intracanal medication may present side effects and jeopardize the therapeutic outcomes. Indeed, clinicians have been aware of these concerns for years. Based on the current evidence of studies, this article reviews the properties of various irrigants and intracanal medicaments and elucidates their effectiveness and interactions. The evolution of different kinetic irrigation methods, their effects, limitations, the paradigm shift, current indications, and effective operational procedures regarding intracanal medication are also discussed. This expert consensus aims to establish the clinical operation guidelines for root canal irrigation and a position statement on intracanal medication, thus facilitating a better understanding of infection control, standardizing clinical practice, and ultimately improving the success of endodontic therapy.

An in vitro study on the degradation of multispecies biofilm of periodontitis-related microorganisms by bovine trypsin.

To investigate the degradation effect of bovine trypsin on multispecies biofilm of periodontitis-related bacteria and to provide an experimental reference for exploring new methods for controlling biofilms of periodontitis-related microorganisms, the multispecies biofilm of periodontitis-related microorganisms was established. Standard strains of Porphyromonas gingivalis, Fusobacterium nucleatum subsp. polymorpha, Actinomyces viscosus, and Aggregatibacter actinomycetemcomitans were co-cultured to form the biofilm. The experimental groups were treated with bovine trypsin, distilled water was applied as the blank control group, and phosphate saline buffer (pH = 7.4) as the negative control group. Morphological observation and quantitative analysis of extracellular polymeric substances (EPS), live bacteria, and dead bacteria were conducted using a laser confocal microscope. The morphological changes of EPS and bacteria were also observed using a scanning electron microscope. The results of morphological observations of modeling were as follows. EPS aggregated as agglomerates, and bacteria flora were wrapped by them, showing a three-dimensional network structure, and channel-like structures were inside the biofilm. Live bacteria were distributed on the surface of the EPS or embedded in them, dead bacteria aggregated between live flora and the bottom layer of biofilms. After being treated with bovine trypsin, the three-dimensional network structure and the channel-like structure disappeared, and the EPS and live and dead bacteria decreased. Quantitative analysis results are as follows. When biofilm was treated for 30 s, 1 min, and 3 min, the minimum effective concentrations of bovine trypsin to reduce EPS were 2 mg/ml (P < 0.05), 0.5 mg/ml (P < 0.05), and 0.25 mg/ml (P < 0.05), respectively. The minimum effective concentrations of bovine trypsin to reduce the live or dead bacteria were 2 mg/ml (P < 0.05), 0.5 mg/ml (P < 0.05), and 0.5 mg/ml (P < 0.05), respectively. There was no significant difference in the ratio of live/dead bacteria after the biofilm was treated for 30 s with bovine trypsin at the concentration of 0.25, 0.5, 1, and 2 mg/ml (P > 0.05), and the minimum effective concentration to reduce the ratio of live bacteria/dead bacteria was 0.25 mg/ml (P < 0.05) after treatment for 1 min and 3 min. Therefore, bovine trypsin can destroy biofilm structure, disperse biofilm and bacteria flora, and reduce the EPS and bacterial biomass, which are positively correlated with the application time and concentration.

[Effect of 17% ethylenediaminetetraacetic acid irrigation on the dentin adhesion of Enterococcus faecalis].

OBJECTIVE: This work aims to uncover the promoting effect of 17% ethylenediaminetetraacetic acid (EDTA) irrigation on the dentin adhesion of Enterococcus faecalis (E. faecalis). METHODS: Forty-eight half split samples and twelve dentin slices were randomly divided into three experimental groups and one control group. The experimental groups and the control group were soaked with EDTA in different time lengths and with normal saline, respectively. E. faecalis was inoculated, and its dentin adhesion was measured via scanning electron microscopy, confocal laser scanning microscopy (CLSM), colony forming unit counts, and histological Gram staining. RESULTS: According to histological Gram staining, the depth showed no statistically significant differences between 1 min group and the control group, 1 min group and 3 min groups (P>0.05). E. faecalis intruded in the dentine tubules (measured by CLSM), and the thickness of the biofilm on the dentin surface and the colony numbers of experimental groups were greater than those of the control group (P<0.05). The differences between the three experimental groups were statistically signi-ficant (P<0.05). CONCLUSIONS: EDTA (17%) irrigation can promote E. faecalis adhesion to dentin. This adhesion would in turn prolong EDTA treatment time.

[Metabonomics study of oral cancer using gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry].

Oral cancer is the sixth common cancer in the world, and precisely distinguishing health control, benign and malignant oral tumors is important for the proper and timely selection of therapeutic treatment. In the current study, the metabolic profiles of the plasma, urine and saliva of three groups, consisting of malignant oral tumor patients, benign oral tumor patients and healthy controls, were analyzed using liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry. Utilizing a partial least squares-discriminant analysis with orthogonal signal correction data filter, the three groups were discriminated based on their plasma, urine and saliva metabolic profiles. Nineteen differential metabolites were identified including 3 acylcarnitines and 4 lyso-phosphatidylcholines in plasma, 3 amino acids and 2 organic acids in urine, 4 organic acids and 3 other metabolites in saliva. The identified metabolites were studied in the context of the pathways in which they were involved and their biological activities. The results indicated that benign and malignant oral tumor patients have altered energy metabolism, disordered lipolysis compared with healthy controls. Furthermore malignant oral tumor patients even present a distorted Krebs cycle and inositol metabolism.

[An animal experiment study on the effect of periodontitis on atherosclerosis].

OBJECTIVE: To make an animal periodontitis and atherosclerosis compound model, and to study the effects of periodontitis on atherosclerosis. METHODS: 36 Japan rabbits were randomly divided into four groups: Including periodontitis model group, periodontitis and atherosclerosis compound model group, atherosclerosis model group and control group. Periodontitis model was initiated by ligating floss around teeth cervical and oral inoculating with Porphyromonas gingivalis (P. gingivalis). Atherosclerosis was established by single iliac artery of balloon-injured rabbit. Histopathological change of injured iliac artery was observed under optical microscope after hematoxylin-eosion stain. Elastica van Gieson-stained sections were used for the morphometric analysis. We measured intimal and medial lesion areas in iliac artery cross-sections as well as the intimal/medial ratio (I/M). We also analyzed P. gingivalis 16S rDNA amplification with nested-polymerase chain reaction (nested-PCR), and detect systemic proinflammatory mediators with enzyme linked immunosorbent assay (ELISA), including C-reactive protein (CRP), interleukin-6 (IL-6) and interleukin-1beta (IL-1beta). RESULTS: The serum levels of CRP, IL-6 and IL-1beta increased obviously among the compound model group than other groups (P<0.01). Histopathological observation revealed the compound model group in I/M was bigger than other groups (P<0.01). P. gingivalis 16S rDNA was detected among the periodontitis model group and the compound model group by nested-PCR. CONCLUSION: Periodontitis may accelerate intimal hyperplasia in balloon-injured iliac arteries by upgrade of systemic inflammation factors and local bacterial infection.

The intervention research on understanding of the AIDS prevention and occupational safety of the dentist in Kunming and west part of Yunnan.

OBJECTIVE: To investigate the knowledge, attitude of the AIDS prevention and occupational safety in dentist in Kunming and west part of Yunnan and evaluate the effect of education and intervention. METHOD: 165 dentists in Yunnan were tested by KABP questionnaire before education. All of the 165 dentists participated a course on AIDS prevention. After that course the same questionnaire was answered by participants. RESULT: The correct rates obviously increased. The understanding rates of the oral prevention measure were obviously improved. CONCLUSION: The knowledge of AIDS prevention is very low in dentist in Kunming and west part of Yunnan. The education intervention can effectively improve the understanding level of the AIDS prevention in dentist.