OBJECTIVE: To explore the effects of two methods of smear layer removal on the surface properties of dentin. METHODS: Sixty extracted sound third molars were collected in this study, and were prepared as uniform dentin specimens with smear layer. All specimens were randomly divided into three groups: Control group, ultrasonic treatment (UT) group and etched treatment (ET) group. Scanning electron microscope (SEM) were used to observe the surface micromorphology of all three groups. Then, the surface elements, mineral phases and functional groups were analyzed by energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and flourier transformed infrared spectrometer (FTIR) respectively. The mechanical properties, hydrophilicity and biocompatibility were also further evaluated. RESULTS: It was revealed that dentin tubules of UT and ET groups were exposed, but lots of dentin debris piled up on the surface of the control one which covered up dentin tubules on the surface. The EDX results should that the weaker peak value of calcium and phosphorus in ET group than control and UT groups. Characteristic peaks of hydroxyapatite could be seen by XRD in all of the three groups, but lower distinctive peaks of amide Ⅰ, Ⅱ and Ⅲ bands of collagen of the dentin surface in control group than in ET and UT groups. The microhardness results showed that ET group was lower than control and UT groups, the difference was significant (P < 0.05). Better hydrophilicity of ET group was investigated (P < 0.05) than control group and UT group. Cells could be observed to adhere normally to dentin surface of each group which meant that all of the three groups had good biocompatibility. CONCLUSION Both UT and ET could effectively remove the smear layer on the surface of dentin and had no adverse effect of the dentin micromorphology and biocompatibility. The ultrasonic removal of the smear layer did not influence the mineral structure, hydrophilicity and mechanical properties of dentin surface. Although ET can effectively improve the hydrophilicity of dentin but decreased mechanical properties and the content of calcium and phosphorus.
Dentin/ultrastructure* ; Humans ; Surface Properties ; Smear Layer ; Molar, Third ; Microscopy, Electron, Scanning ; Dental Etching/methods*

Peri-implantitis is a pathologic condition associated with dental plaque that occurs in the implant tissue and is characterized by inflammation of the mucous membrane surrounding the implant, followed by the progressive loss of supporting bone. In this study, a case of guided bone regeneration therapy based on plaque control of peri-implant inflammation was reported. Four years after surgery for the left second premolar implant, the patient presented with "left lower posterior tooth swelling and discomfort for more than 2 years". The X-ray periapical film showed a decrease in distal bone mineral density of implant, and the clinical diagnosis was peri-implantitis of the left second premolar. Implants underwent guided bone regeneration and regular periodontal maintenance treatment. Re-examination at 3.5 months, 11 months, 18 months, and 7 years showed that the alveolar bone height and bone mineral density were stable, and the periodontal depth became shallow. However, the gingival recession was mild. In the present case, follow-up at 7 years demonstrated that the clinical periodontal indexes could be remarkably improved after complete periodontal treatment for peri-implantitis, and the alveolar bone could be well restored and regenerated.
Humans ; Peri-Implantitis/etiology* ; Follow-Up Studies ; Bone Regeneration ; Guided Tissue Regeneration, Periodontal/methods* ; Dental Plaque/prevention & control* ; Male ; Female ; Dental Implants/adverse effects*

OBJECTIVES: This study aimed to evaluate the therapeutic effect of 1% povidone-iodine mouthwash combined with scaling and root planing in patients with stage Ⅰ/Ⅱ class A/B periodontitis, and to provide a basis for the clinical application of povidone-iodine mouthwash. METHODS: Seventy-five subjects were included in this trial and randomly divided into three groups. After full-mouth ultrasonic supragingival cleansing, scaling and root planing, the placebo group was treated with sodium chloride injection (NaCl group), the control group was treated with compound chlorhexidine mouthwash (CHX group), and the experimental group was treated with 1% povidone-iodine mouthwash (PVP-I group), and rinsed their mouths for 1 week, respectively. Subjects were tested at 1, 4, and 12 weeks after dosing for clinical indicators, microbial composition of supragingival plaque, gingival crevicular fluid inflammatory marker levels, and patient-reported outcomes. RESULTS: Sixty-three subjects completed the follow-up. After treatment, the clinical indicators, microbial indicators, and inflammatory indicators were all significantly improved (P<0.05). Comparisons among the groups showed that one week after treatment, the bleeding index and plaque index of the CHX group and the PVP-I group were lower than those of the NaCl group, and the plaque index of the CHX group was lower than that of the PVP-I group (P<0.05). There were no statistically significant differences in the other clinical indicators among the groups (P>0.05). Twelve weeks after treatment, the Shannon index of the CHX group was lower than that of the NaCl group (P<0.05), and there were no statistically significant differences in the other microbial indicators among the groups (P>0.05). Twelve weeks after treatment, the interleukin-10 concentration of the CHX group was higher than that of the NaCl group (P<0.05), and there were no statistically significant differences in the other inflammatory indicators among the groups (P>0.05). The PVP-I group had the highest scores in terms of taste and oral odor. There was no obvious staining on the tooth surfaces and mucosa in all three groups. CONCLUSIONS 1% PVP-I mouthwash combined with scaling and root planing can effectively reduce gingival inflammation and dental plaque, improve clinical symptoms in the short term. While its efficacy is not significantly inferior to that of chlorhexidine, PVP-I mouthwash is more acceptable to patients than chlorhexidine.
Humans ; Povidone-Iodine/administration & dosage* ; Mouthwashes/therapeutic use* ; Dental Scaling ; Root Planing ; Periodontitis/microbiology* ; Gingival Crevicular Fluid/chemistry* ; Anti-Infective Agents, Local/therapeutic use* ; Female ; Male ; Chlorhexidine/therapeutic use* ; Dental Plaque/microbiology* ; Middle Aged ; Adult

The reduction of nitrate to nitrite by the oral microbiota has been proposed to be important for oral health and results in nitric oxide formation that can improve cardiometabolic conditions. Studies of bacterial composition in subgingival plaque suggest that nitrate-reducing bacteria are associated with periodontal health, but the impact of periodontitis on nitrate-reducing capacity (NRC) and, therefore, nitric oxide availability has not been evaluated. The current study aimed to evaluate how periodontitis affects the NRC of the oral microbiota. First, 16S rRNA sequencing data from five different countries were analyzed, revealing that nitrate-reducing bacteria were significantly lower in subgingival plaque of periodontitis patients compared with healthy individuals (P < 0.05 in all five datasets with n = 20-82 samples per dataset). Secondly, subgingival plaque, saliva, and plasma samples were obtained from 42 periodontitis patients before and after periodontal treatment. The oral NRC was determined in vitro by incubating saliva with 8 mmol/L nitrate (a concentration found in saliva after nitrate-rich vegetable intake) and compared with the NRC of 15 healthy individuals. Salivary NRC was found to be diminished in periodontal patients before treatment (P < 0.05) but recovered to healthy levels 90 days post-treatment. Additionally, the subgingival levels of nitrate-reducing bacteria increased after treatment and correlated negatively with periodontitis-associated bacteria (P < 0.01). No significant effect of periodontal treatment on the baseline saliva and plasma nitrate and nitrite levels was found, indicating that differences in the NRC may only be revealed after nitrate intake. Our results suggest that an impaired NRC in periodontitis could limit dietary nitrate-derived nitric oxide levels, and the effect on systemic health should be explored in future studies.
Humans ; Nitrates ; Nitric Oxide ; Nitrites ; RNA, Ribosomal, 16S/genetics* ; Periodontitis/microbiology* ; Bacteria ; Dental Plaque/microbiology* ; Saliva/microbiology* ; Microbiota/genetics*

OBJECTIVES: This study aimed to compare the effectiveness of ultrasound and acoustic and laser cleaning of curved root canals. METHODS: A total of 92 molars with independent root canals with a curvature of 20°-40° were prepared and standardized at 04 25# and stained with gentian violet solution for 72 h. Among them, 52 were randomly divi-ded into four groups for final rinsing (n=13): NI group, PUI group, EDDY group, and PIPS group. Ten samples in each group were cut horizontally along the long axis perpendicular to the root and divided into curved upper, curved, and apical segments. Images were taken with a stereomicroscope and Image J measurements were taken to calculate the depth of rinse penetration. The remaining three samples from each group were split along the long axis of the dentin, photographed by scanning electron microscope to record the dentin tubule exposure and staining layer, and scored for staining layer by double-blind method. SPSS 26.0 software was used to perform statistical analysis and select the best flushing method. An extra 40 samples were randomly divided into four groups for detection of flushing fluid penetration depth (n=10): 10, 20, 30, and 40 s. RESULTS: In the upper part, the mean depth of infiltration was not significantly different between the experimental and control groups (P>0.05). The PIPS group had a significantly lower smear layer score than the control group and the EDDY group (P<0.01). In the curved segment, the mean depth of infiltration was significantly greater in the PUI group than in the control group (P<0.05); the tarnish layer score was lower in each experimental group than in the control group. At the top, the mean depth of infiltration was greater in the PUI and PIPS groups than in the control group (P<0.05), and the smear layer score was lower in the PIPS group than in the other groups (P<0.05). After the time was changed, the depth of infiltration of PUI increased only in the apical segment as the flushing time increased. CONCLUSIONS The PUI and PIPS methods facilitate the penetration of irrigation solution into the dentin canal in curved root canals, especially in the apical segment. The PIPS technique is effective in removing the smear layer in curved root canals.
Humans ; Dental Pulp Cavity ; Microscopy, Electron, Scanning ; Root Canal Irrigants ; Root Canal Preparation/methods* ; Smear Layer ; Sodium Hypochlorite ; Therapeutic Irrigation/methods* ; Double-Blind Method

Streptococcus mutans (S. mutans) is generally regarded as a major contributor to dental caries because of its ability to synthesize extracellular polysaccharides (EPS) that aid in the formation of plaque biofilm. The VicRKX system of S. mutans plays an important role in biofilm formation. The aim of this study was to investigate the effects of vicK gene on specific characteristics of EPS in S. mutans biofilm. We constructed single-species biofilms formed by different mutants of vicK gene. Production and distribution of EPS were detected through atomic force microscopy, scanning electron microscopy and confocal laser scanning microscopy. Microcosmic structures of EPS were analyzed by gel permeation chromatography and gas chromatography-mass spectrometry. Cariogenicity of the vicK mutant was assessed in a specific pathogen-free rat model. Transcriptional levels of cariogenicity-associated genes were confirmed by quantitative real-time polymerase chain reaction. The results showed that deletion of vicK gene suppressed biofilm formation as well as EPS production, and EPS were synthesized mostly around the cells. Molecular weight and monosaccharide components underwent evident alterations. Biofilms formed in vivo were sparse and contributed a decreased degree of caries. Moreover, expressional levels of genes related to EPS synthesis were down-regulated, except for gtfB. Our report demonstrates that vicK gene enhances biofilm formation and subsequent caries development. And this may due to its regulations on EPS metabolism, like synthesis or microcosmic features of EPS. This study suggests that vicK gene and EPS can be considered as promising targets to modulate dental caries.
Animals ; Biofilms ; Dental Caries ; Dental Plaque ; Rats ; Streptococcus mutans/genetics*

OBJECTIVES: To compare the treatment effects of periodontal endoscope-assisted and traditional subgingival scaling on residual pockets. METHODS: A total of 13 patients with periodontitis from Dept. of Periodontics, West China Hospital of Stomatology, Sichuan University were recruited. After 4-6 weeks of initial treatment, the residual pockets with a probing depth (PD) of ≥4 mm and attachment loss (AL) of ≥4 mm and bleeding on probing were examined with traditional (control group) and periodontal endoscope-assisted subgingival scaling (endoscopy group) in a randomly controlled split-mouth design. At baseline and 6 weeks and 3 months after treatment, plaque index (PLI), PD, AL, and bleeding index (BI) were measured. Differences in these clinical parameters within and between groups and patient-reported outcomes were compared. RESULTS: A total of the 694 sites of 251 teeth were included in this trial. Both groups showed significant improvement in each periodontal parameters 6 weeks and 3 months after treatment ( CONCLUSIONS Periodontal endoscope-assisted subgingival scaling resulted in better effects than traditional subgingival scaling when the residual pockets were in a single-rooted tooth, with a PD of ≥5 mm but without vertical alveolar bone resorption and furcation involvement.
Dental Plaque Index ; Dental Scaling ; Endoscopes ; Humans ; Periodontitis/therapy*

The aim of this study was to compare the efficiency of four final irrigation protocols in smear layer removal and bacterial inhibition in root canal systems. Thirty roots inoculated with Enterococcus faecalis were prepared with ProTaper Universal files. The teeth were disinfected by conventional needle irrigation, sonic agitation using the EndoActivator device, passive ultrasonic irrigation, or an M3 Max file. Teeth with no root canal preparation served as blank controls for the establishment of the infection baseline. Teeth with preparation but no final irrigation served as a post-instrumentation baseline. After the final irrigation, the teeth were sectioned in half. One half of each tooth was examined by scanning electron microscopy (SEM) to assess smear layer removal using a five-point scale. The other half was examined by confocal laser scanning microscopy (CLSM) using the LIVE/DEAD BackLight bacterial viability kit to evaluate the depth of bacterial survival in dentinal tubules. SEM analysis revealed no significant difference in smear layer removal throughout the whole canal among the EA, PUI, and M3 Max groups (P > 0.05). CLSM revealed that PUI achieved the greatest bacterial inhibition depth in the coronal ((174.27 ± 31.63) μm), middle ((160.94 ± 37.77) μm), and apical ((119.53 ± 28.49) μm) thirds of the canal (all P < 0.05 vs. other groups). According to this comprehensive SEM and CLSM evaluation, PUI appears to have the best infection control ability in root canal systems.
Dental Pulp Cavity ; Edetic Acid ; Humans ; Microscopy, Electron, Scanning ; Root Canal Irrigants ; Root Canal Preparation ; Smear Layer ; Sodium Hypochlorite

The oral microbial community is widely regarded as a latent reservoir of antibiotic resistance genes. This study assessed the molecular epidemiology, susceptibility profile, and resistance mechanisms of 35 methicillin-resistant Staphylococcus epidermidis (MRSE) strains isolated from the dental plaque of a healthy human population. Broth microdilution minimum inhibitory concentrations (MICs) revealed that all the isolates were nonsusceptible to oxacillin and penicillin G. Most of them were also resistant to trimethoprim (65.7%) and erythromycin (54.3%). The resistance to multiple antibiotics was found to be largely due to the acquisition of plasmid-borne genes. The mecA and dfrA genes were found in all the isolates, mostly dfrG (80%), aacA-aphD (20%), aadD (28.6%), aphA3 (22.9%), msrA (5.7%), and the ermC gene (14.3%). Classical mutational mechanisms found in these isolates were mainly efflux pumps such as qacA (31.4%), qacC (25.7%), tetK (17.1%), and norA (8.6%). Multilocus sequence type analysis revealed that sequence type 59 (ST59) strains comprised 71.43% of the typed isolates, and the eBURST algorithm clustered STs into the clonal complex 2-II(CC2-II). The staphyloccoccal cassette chromosome mec (SCCmec) type results showed that 25 (71.43%) were assigned to type IV. Moreover, 88.66% of the isolates were found to harbor six or more biofilm-associated genes. The aap, atlE, embp, sdrF, and IS256 genes were detected in all 35 isolates. This research demonstrates that biofilm-positive multiple-antibiotic-resistant ST59-SCCmec IV S. epidermidis strains exist in the dental plaque of healthy people and may be a potential risk for the transmission of antibiotic resistance.
Anti-Bacterial Agents ; therapeutic use ; Dental Plaque ; microbiology ; Female ; Humans ; Methicillin ; Methicillin-Resistant Staphylococcus aureus ; isolation & purification ; Staphylococcal Infections ; diagnosis ; Staphylococcus epidermidis ; isolation & purification

PURPOSE: The aim of this study is to evaluate the effectiveness of MnO₂-diatom microbubbler (DM) on the surface of prosthetic materials as a mouthwash by comparing the biofilm removal effect with those previously used as a mouthwash in dental clinic.MATERIALS AND METHODS: DM was fabricated by doping manganese dioxide nanosheets to the diatom cylinder surface. Scanning electron microscopy (SEM) was used to observe the morphology of DM and to analyze the composition of doped MnO₂. Stereomicroscope was used to observe the reaction of DM in 3% hydrogen peroxide. Non-precious metal alloys, zirconia and resin specimens were prepared to evaluate the effect of biofilm removal on the surface of prosthetic materials. And then Streptococcus mutans and Porphyromonas gingivalis biofilms were formed on the specimens. When 3% hydrogen peroxide solution and DM were treated on the biofilms, the decontamination effect was compared with chlorhexidine gluconate and 3% hydrogen peroxide solution by crystal violet staining.RESULTS: Manganese dioxide was found on the surface of the diatom cylinder, and it was found to produce bubble of oxygen gas when added to 3% hydrogen peroxide. For all materials used in the experiments, biofilms of the DM-treated groups got effectively removed compared to the groups used with chlorhexidine gluconate or 3% hydrogen peroxide alone.CONCLUSION: MnO₂-diatom microbubbler can remove bacterial membranes on the surface of prosthetic materials more effectively than conventional mouthwashes.
Alloys ; Biofilms ; Chlorhexidine ; Decontamination ; Dental Clinics ; Dental Plaque ; Diatoms ; Gentian Violet ; Hydrogen Peroxide ; In Vitro Techniques ; Manganese ; Membranes ; Microscopy, Electron, Scanning ; Mouthwashes ; Oral Hygiene ; Oxygen ; Porphyromonas gingivalis ; Streptococcus mutans