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Abstract To investigate the effect of Er:YAG laser treatment on lipopolysaccharide (LPS) clearance and fibroblast adhesion on titanium disks. Grade IV titanium discs (n = 216) were used and allocated to 6 groups. Group 1 was the negative control without Porphyromonas gingivalis inoculation. Discs in Groups 2–6 were incubated with P. gingivalis to form a biofilm. Group 3 received 0.12% chlorhexidine irrigation and Group 4 received titanium curettage to remove the biofilm. Group 5 was treated with Er:YAG laser irradiation and Group 6 was treated with titanium curettage plus Er:YAG laser irradiation. The contact angle and surface roughness were measured after the various treatments. The surface microstructure and residual bacteria were examined using scanning electron microscopy and confocal laser scanning microscopy, respectively. Residual LPS was examined using a limulus amoebocyte lysate assay and human gingival fibroblast adhesion was quantified using fluorescent microscopy. Curettage plus Er:YAG laser irradiation was the most effective method for removing bacteria and LPS. No significant difference in the amount of fibroblast adhesion was found between the control and Group 6. Combined use of Er:YAG laser irradiation and curettage optimizes LPS clearance and fibroblast adhesion on titanium discs.

Objectives: Titanium implants are regarded as a promising treatment modality for replacing missing teeth. Osteointegration and antibacterial properties are both desirable characteristics for titanium dental implants. The aim of this study was to create zinc (Zn)-, strontium (Sr)-, and magnesium (Mg)-multidoped hydroxyapatite (HAp) porous coatings, including HAp, Zn-doped HAp, and Zn-Sr-Mg-doped HAp, on titanium discs and implants using the vapor-induced pore-forming atmospheric plasma spraying (VIPF-APS) technique. Methods: The mRNA and protein levels of osteogenesis-associated genes such as collagen type I alpha 1 chain (COL1A1), decorin (DCN), osteoprotegerin (TNFRSF11B), and osteopontin (SPP1) were examined in human embryonic palatal mesenchymal cells. The antibacterial effects against periodontal bacteria, including Porphyromonas gingivalis and Prevotella nigrescens, were investigated. In addition, a rat animal model was used to evaluate new bone formation via histologic examination and micro-computed tomography (CT). Results: The ZnSrMg-HAp group was the most effective at inducing mRNA and protein expression of TNFRSF11B and SPP1 after 7 days of incubation, and TNFRSF11B and DCN after 11 days of incubation. In addition, both the ZnSrMg-HAp and Zn-HAp groups were effective against P. gingivalis and P. nigrescens. Furthermore, according to both in vitro studies and histologic findings, the ZnSrMg-HAp group exhibited the most prominent osteogenesis and concentrated bone growth along implant threads. Significance: A porous ZnSrMg-HAp coating using VIPF-APS could serve as a novel technique for coating titanium implant surfaces and preventing further bacterial infection.

Rheumatoid arthritis (RA) and periodontitis are suggested to be closely linked based on microbial dysbiosis, but limited subgingival bacteria have been proven in the pathogenesis of RA. We enrolled 30 RA patients and 25 controls and divided them into three groups with matched age, gender, and diabetes statuses: group AM (all of the matched participants), group PD (periodontally diseased), and group PH (periodontally healthy). Their subgingival microbial composition was determined by V3–V4 16S rRNA gene sequencing. Significant differences in subgingival microbial clustering between the RA patients and controls were observed in groups AM and PD. Among the taxa enriched in RA, Aminipila butyrica and Peptococcus simiae were the only two species displaying positive correlation to the level of anti-citrullinated protein antibodies (ACPAs) in both of the groups. Surprisingly, the median of relative abundances of A. butyrica and P. simiae were 0% in the controls of group PD. Furthermore, a gene encoding arginine deiminase with the capability to produce citrulline was addressed in the complete genome sequence of A. butyrica. This is the first study to elucidate the important roles of A. butyrica and P. simiae as periodontal bacteria leading to RA possibly through the induction of ACPA production.

A whole-genome microarray is utilized to analyze the transcription profile of the adaptive acid tolerance response (ATR) in Streptococcus mutans. An optimal acid adaption in S. mutans could be promoted by downregulation of the synthesis of the amino acid precursors in response to acid challenge.

Very severe inclination of the mandibular second molar is a difficult challenge for dentists. Severe impaction of the mandibular second molars often leads to their extraction to avoid potential damage to the root of the first molars and provide space for the eruption of the third molars. An ideal treatment is orthodontic uprighting with or without surgical uncovering, and one of the effective appliances for molar uprighting is the tip-back cantilever technique. This paper presents the successful tip-back sectional archwire orthodontic treatment of impacted mandibular second molars. [ABSTRACT FROM AUTHOR]

Background: The purpose of this study is to investigate how the components of biofilm and clinical oral status change in adolescents and to identify specific periodontal pathogens as risk markers for the onset of periodontitis. Methods: One hundred seven high school students (72 boys and 35 girls, all 15 years old) were recruited. The mesio-lingual site of the left lower first molar was selected as the examined site. Probing depth (PD), bleeding on probing (BOP), the presence of subgingival calculus, and Community Periodontal Index (CPI) were determined by examination with a WHO probe The prevalence and proportion of seven selected periodontal pathogens (Porphyromonas gingivalis, Tannerella forsythensis, Prevotella intermedia, Campylobacter rectus, Eikenella corrodens, and Actinobacillus actinomycetemcomitans serotypes b and c) were determined by indirect immunofluorescent technique, and the prevalence and proportion of spirochetes were determined by their morphology under dark-field microscopy. The relationship between the periodontal status and the bacterial condition was statistically analyzed. Results: The mean proportion of T. forsythensis was significantly higher in BOP (+) sites compared with BOP (-) sites (3.47% ± 5.35% versus 0.85% ± 1.95%) and in CPI 3 sites compared with CPI 0 sites (3.29% ± 5.28% versus 0.68% ± 1.37%). The mean proportion of C. rectus was significantly increased in BOP (+) compared with BOP (-) (2.01% ± 2.48% versus 0.79% ± 0.91%) and in CPI 3 sites compared with CPI 0 sites (2 04% ± 2.64% versus 0.80% ± 0.79%). Conclusion: The results indicated that T. forsythensis and C. rectus might be able to be used as risk markers for the onset of periodontitis. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effects of herbal medicines in treating periodontal diseases. Three Chinese herbal composites [Conth Su (CS), Chi Tong Ning (CTN) and Xi Gua Shuang (XGS)], widely used for prevention and treatment of periodontal diseases, and the major components of these composites were tested for their ability to: (1) alleviate disease progression of experimental periodontitis in hamsters, (2) inhibit bacterial growth, and (3) induce mutations. Our results indicate that in treating experimental periodontitis, there were no significant differences between the animal groups with or without the use of Chinese herbal medicines in terms of the degree of inflammation, alveolar bone resorption, and rate of repair. However, hamsters treated with CS presented earlier regenerative epithelium. CTN demonstrated superior bacterial inhibition ability among all tested herbs (MIC 0.025 g/ml); CS showed good anti-bacterial abilities at a concentration of 0.05 g/ml. It is interesting to note that while both CS and CTN were capable of inhibiting bacterial growth, none of the individual herb components showed comparable bacterial inhibition abilities. None of the tested herbal composites or their components showed signs of inducing cell mutations using the Ames test. These results indicated that traditional Chinese herbal medicines, which have been used to treat periodontal diseases for hundreds of years by Chinese people, can effectively inhibit bacterial growth without causing cell mutation. Further investigation into their possible clinical applications in periodontal therapy is encouraged. [ABSTRACT FROM AUTHOR]

Background: The purpose of this study was to determine the prevalence and distribution of Eikenella corrodens (E. corrodens) in subgingival plaque in different age and periodontitis groups and to examine whether its presence is related to periodontal diseases. Methods: A total of 273 subgingival plaque samples from 213 periodontitis patients and 60 healthy subjects were assessed. Smears from each plaque sample were made and E. corrodens was detected by means of indirect immunofluorescent technique. Mean percentage of E. corrodens per total bacteria (distribution) was calculated in each sample. The prevalence (% of positive samples) and distribution of E. corrodens were statistically analyzed based on age or diagnosis by means of Fisher's exact test and analysis of variance (ANOVA). Results: Prevalence of E. corrodens decreased by age in the healthy control group; however, prevalence did not change in periodontitis groups. Distribution of E. corrodens was highest in juvenile periodontitis (JP) (2.3 ± 1.5%) followed by post-JP (1.7 ± 2.1%1, prepubertal periodontitis (1.4 ± 1.1%), rapidly progressive periodontitis (0.8 ± 0.7%), adult periodontitis (0.7 ± 0.6%), and healthy subjects (0.3 ± 0.3%) (ANOVA, P <0.0001). The <20-year-old age group with periodontitis showed the highest distribution of E. corrodens (2.2 ± 1.6%) compared to the older age groups who were either healthy or had periodontitis (ANOVA, P<0.0001). Conclusions: Since the distribution of E. corrodens is significantly higher in JP, post-JP, and PP, E. corrodens might play an important role in the occurrence or progression of periodontitis in young patients. [ABSTRACT FROM AUTHOR]

Background: The purpose of this report was to compare the distribution of periodontal pathogens recovered from failing implants and teeth with adult and recurrent forms of periodontitis. Methods: A total of 41 consecutive microbial samples from patients with failing implants (IMP) were received at the Microbiology Testing Laboratory (MTL) of the University of Pennsylvania over a 2-year period. Paired control samples were selected from samples received concurrently by MTL from 41 patients with a diagnosis of adult periodontitis (AP) and 41 with a diagnosis of recurrent or refractory periodontitis (RP). Patients' mean ages for the 3 categories were 59, 47, and 53 years, respectively. Samples were collected with paper points or sealers and shipped in prereduced medium by express mail to the laboratory where they were processed within 48 hours from the time of collection. Culture was used for detection of A. actinomycetemcomitans, C. rectus, P. intermedia/nigrescens, E. corrodens, P. micros, Capnocytophaga and Fusobacterium sp., enteric Gram-negative rods, Enterococcus and Staphylococcus sp., and yeast. P. gingivalis and B. forsythus were detected by indirect immunofluorescence. Morphotypes were enumerated by dark-field microscopy. Results: The most frequently detected microorganisms from IMP were B. forsythus (59%), spirochetes (54%), Fusobacterium (41%), P. micros (39%), and P. gingivalis (27%). Recovery levels (mean ± SD) were 1±1, 4±5, 4±5, 9±11, 1±2, respectively. The most frequently detected organisms for AP were B. forsythus (83%), Fusobacterium (80%), spirochetes (79%), P. gingivalis (59%), P. micros (51%), and E. corrodens (37%), at levels 2±2, 5±4, 9±6, 4±5, and 6±7, respectively. Corresponding data for RP were B. forsythus (85%), Fusobacterium (83%), P. gingivalis (60%), spirochetes (59%), C. rectus (56%), and P. micros (56%), at levels of 3±2, 8±8, 4±4, 2±2, 1±1, and 9±10, respectively. Conclusions: These results indicate that the detection frequency and levels of recovery of some periodontal pathogens in failing implants are significantly different from that of teeth with periodontitis; however, the detection frequency and levels of recovery are similar in teeth affected by adult and refractory (recurrent) forms of periodontitis. [ABSTRACT FROM AUTHOR]

Demineralization of teeth with their adherent bacterial flora is a prerequisite for the localization of selected species in sections of undisturbed bacterial deposits by immunoelectron microscopy. The effect of EDTA demineralization on the immunological labeling of Gram-positive and Gram-negative oral bacteria was tested on strains of Actinomyces viscosus, A. israelii. Eikenella corrodens, Bacteroides melaninogenicus. Capnocytophaga sputigena and Wolinella recta. After 3 months in EDTA, cells prefixed in paraformaldehyde-picric acid were washed and incubated with homologous rabbit antiserum followed by goat anti-rabbit lgG to enhance the immunocoating reaction. Samples were then processed for transmission electron microscopy. Control specimens included (1) demineralized cells incubated with pre-immune rabbit sera instead of homologous antisera (2) cells stored for 3 months in PBS instead of EDTA (3) fresh cells processed for immunocoating immediately after prefixation and washing. No detectable immunocoating layer was found on the cells of the control group incubated with pre-immune rabbit serum. EDTA treated cells demonstrated an immunocoating layer of similar density and thickness to that of cells stored in PBS, or fresh cells. The results indicate that immunoelectron microscopic localization of bacterial cells may be feasible in ultrathin sections of demineralized dental specimens. [ABSTRACT FROM AUTHOR]

A total of 10 strains of Bacteroides melaninogenicus subspecies were examined by transmission electron microscopy after conventional processing, and staining with uranyl acetate and lead citrate. All strains examined had a cell periphery with a basic ultrastructure typical of that reported for other Gram-negative bacteria. However, only s.s. asaccharolyticus strains exhibited a moderately electron-dense covering layer, 16-19 nm thick, in contact with the outer membrane of the cell wall, and numerous intercellular membranous vesicles. S.s. melaninogenicus strains, in contrast to those of other subspecies, had no extramural structures, and exhibited a distinct, intercellular, fibrillar matrix. S.s. intermedius cells featured a 9-14 urn thick, electron-dense extramural layer which was separated by an electron-lucent layer of similar thickness from the outer membrane of the wall. These morphological differences may be useful in differentiating these subspecies from one another. [ABSTRACT FROM AUTHOR]

Background/purpose: Streptococcus sanguinis is an early colonizer of biofilm and plays a key role in the process of adhesion to prosthetic surfaces by facilitating the adhesion of later colonizers. The main aim of this study was to determine if S. sanguinis is affected by the gold concentration dental prosthetic alloys. Materials and methods: Five commonly used alloys with varying degrees of gold concentration were selected for this study. We evaluated the ability of S. sanguinis ATCC strain 10556 to adhere to each of these alloys by counting the number of cells that adhered to each of the tested alloys. Each alloy was also assessed for cell adherence using scanning electron microscopy. One-way analysis of variance and Student–Newman–Keuls comparison test were used for statistical analysis based on cell counts from each well for the test and control groups. Results: The highest concentration of bacterial cells adhered best to pure gold alloy (458±8) followed by 88.4% gold Je alloy (382.33±2), 56% gold Wi alloy (269±4), 2% gold Es alloy (212.33±2), and nongold Re alloy (183±3). Based on the cell counts and scanning electron microscopy observations, there was a clear correlation between gold concentration and S. sanguinis adherence. Conclusion: The findings of this study suggest that alloys with a lower gold concentration may result in lower bacterial colonization rates and may reduce the risk of invasive infections. When choosing an alloy, low gold concentrations may be a better clinical choice.