Vapor-Induced Pore-Forming Atmospheric-Plasma-Sprayed Zinc-, Strontium-, and Magnesium-Doped Hydroxyapatite Coatings on Titanium Implants Enhance New Bone Formation-An In Vivo and In Vitro Investigation.

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.

Efficacy of Er:YAG laser for the peri-implantitis treatment and microbiological changes: a randomized controlled trial.

The aims of this study were to identify the microbiological changes in the periodontal pockets following an Er:YAG laser (ERL) irradiation and mechanical debridement to compare the effectiveness of ERL irradiation to mechanical debridement for peri-implantitis treatment through randomized controlled trials. Twenty-three patients with peri-implantitis lesions were treated in either a test group, ERL set at energy level of 100 mJ/pulse, frequency of 10 Hz, pulse duration was 100 µs, and irradiated by three passages, or a control group, with mechanical debridement using an ultrasonic scaler. An examiner measured the following clinical parameters at different stages (a baseline and at 3- and 6-month post-treatment): probing depth (PD), bleeding on probing (BOP), marginal bone loss (MBL), and anaerobic bacteria counts. Linear regression, with generalized estimation equations, was used to compare the clinical parameters and anaerobic bacterial counts at different stages and between groups. The anaerobic bacterial counts significantly decreased within the control group during the follow-ups. At the 6-month follow-up, both groups showed a significant reduction in PD (test group: mean difference of 0.84 mm; control group: mean difference of 0.41 mm), and the test group showed a significantly higher PD reduction on the buccal site (1.31 mm) compared to that of the control group (0.25 mm). Both ERL and mechanical debridement treatments led to significant improvements in PD. When mechanical debridement therapy was used, significant anaerobic bacterial count reductions were observed. Future treatment of peri-implantitis should involve a combination of both of these therapies.

Subgingival Microbiome in Rheumatoid Arthritis Patients with Periodontitis.

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.

Er:YAG laser irradiation enhances bacterial and lipopolysaccharide clearance and human gingival fibroblast adhesion on titanium discs.

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.

The treatment response of barrier membrane with amoxicillin-loaded nanofibers in experimental periodontitis.

BACKGROUND: Infection control is a major determinant of guided tissue regeneration (GTR). This study aims to develop an antibiotic-loaded membrane to assist periodontal repair. METHODS: Poly(D,L-lactic acid) (PDLLA) nanofibers encapsulating amoxicillin (PDLLA-AMX) were fabricated using the electrospinning technique, and their structures, drug encapsulation efficiency, and release characteristics were assessed. The viability and behaviors of periodontal ligament (PDL) cells on nanofibers, and antibacterial capabilities of nanofibers were evaluated in vitro. Early therapeutic efficiency of the antibiotic-loaded membranes was investigated in rats with ligature-induced experimental periodontitis, and the outcomes were evaluated by gene expression, microcomputed tomography imaging, and histology within 7 days of membrane placement. RESULTS: AMX was successfully encapsulated in the PDLLA nanofibers and released in a sustained manner. After initial attachment was achieved, cells stretched out along with the directions of nanofibers. The viability and expression of migration-associated gene of PDL cells were significantly improved, and the growth of Streptococcus sanguinis and Porphyromonas gingivalis was significantly reduced in the PDLLA-AMX group compared with the controls. On PDLLA-AMX-treated sites, wound dehiscence and sulcular inflammation were reduced. Collagen fiber matrix deposition was accelerated with upregulated type I collagen and interleukin-1ß, and downregulated matrix metalloproteinase-8, whereas periodontal bone level and the expressions of vascular endothelial growth factor and core-binding factor subunit alpha-1 were equivalent to conventional membrane treatment. CONCLUSIONS: PDLLA-AMX nanofibers inhibited bacterial growth and promoted the viability and mobility of PDL cells after initial cell attachment. Membranes with PDLLA-AMX nanofibers reduced inflammation and accelerated periodontal repair at an early stage, providing good prospects for the further development of GTR membranes.

Role of GlnR in acid-mediated repression of genes encoding proteins involved in glutamine and glutamate metabolism in Streptococcus mutans.

The acid tolerance response (ATR) is one of the major virulence traits of Streptococcus mutans. In this study, the role of GlnR in acid-mediated gene repression that affects the adaptive ATR in S. mutans was investigated. Using a whole-genome microarray and in silico analyses, we demonstrated that GlnR and the GlnR box (ATGTNAN(7)TNACAT) were involved in the transcriptional repression of clusters of genes encoding proteins involved in glutamine and glutamate metabolism under acidic challenge. Reverse transcription-PCR (RT-PCR) analysis revealed that the coordinated regulation of the GlnR regulon occurred 5 min after acid treatment and that prolonged acid exposure (30 min) resulted in further reduction in expression. A lower level but consistent reduction in response to acidic pH was also observed in chemostat-grown cells, confirming the negative regulation of GlnR. The repression by GlnR through the GlnR box in response to acidic pH was further confirmed in the citBZC operon, containing genes encoding the first three enzymes in the glutamine/glutamate biosynthesis pathway. The survival rate of the GlnR-deficient mutant at pH 2.8 was more than 10-fold lower than that in the wild-type strain 45 min after acid treatment, suggesting that the GlnR regulon participates in S. mutans ATR. It is hypothesized that downregulation of the synthesis of the amino acid precursors in response to acid challenge would promote citrate metabolism to pyruvate, with the consumption of H(+) and potential ATP synthesis. Such regulation will ensure an optimal acid adaption in S. mutans.

Core-Shell poly-(D,l-Lactide-co-Glycolide)-chitosan Nanospheres with simvastatin-doxycycline for periodontal and osseous repair.

This study aimed to evaluated the potential of core-shell poly(D,l-lactide-co-glycolide)-chitosan (PLGA-chitosan) nanospheres encapsulating simvastatin (SIM) and doxycycline (DOX) for promoting periodontal and large-sized osseous defects. SIM, and/or DOX were encapsulated in PLGA-chitosan nanospheres using double emulsion technique and were delivered to sites of experimental periodontitis and large-sized mandibular osseous defects of rats for 1-4 weeks. The resultant nanospheres were ~ 200 nm diameter with distinct core-shell structure and released SIM and DOX sustainably for 28 days. DOX and SIM-DOX nanospheres significantly inhibited P. gingivalis and S. sanguinis. In experimental periodontitis sites, SIM-DOX nanospheres significantly down-regulated IL-1b and MMP-8 and significantly reduced bone loss. In mandibular osseous defects, VEGF was up-regulated, and osteogenesis was significantly augmented with SIM nanospheres treatment. In conclusion, core-shell PLGA-chitosan nanospheres released SIM and DOX sustainably. SIM-DOX and SIM nanospheres could be considered to promote the repair of infected periodontal sites and non-infected osseous defects respectively.

A new method of assessing aerosolized bacteria generated during orthodontic debonding procedures.

INTRODUCTION: The main objective of this study was to assess the efficacy of a new and innovative method of harvesting bacteria that are aerosolized during orthodontic debonding. Additionally, the protection efficacy of several commercially available masks from such aerosols was assessed in a pilot study. METHODS: Twenty-six subjects were debonded during aerosol sampling, by using an innovative collection system to harvest bonding dust liberated during debonding. Dark-field microscopy, gram-stain microscopy, and chemical identification were used to determine speciation of the collected aerosol from 23 subjects. Three additional subjects were used to test 3 commercial dental or protective masks to determine whether they provide effective protection from the aerosol. RESULTS: Twenty-one species of oral bacteria were identified by the new sampling technique. Two of the 3 masks that were tested offered no protection against the aerosolized bacteria. CONCLUSIONS: A new and effective method for collecting airborne bacteria is presented. Some conventional dental masks offer no protection from aerosolized organisms liberated during debonding procedures. Further assessment of mask efficacy is ongoing.

Surface property alterations and osteoblast attachment to contaminated titanium surfaces after different surface treatments: An in vitro study.

BACKGROUND: Studies have reported a high prevalence of peri-implantitis. The etiology of peri-implantitis remains unclear and no available treatments result in total resolution of established peri-implantitis. PURPOSE: To investigate the factors that interfere with osteoblast adhesion to contaminated titanium surfaces after different surface treatments. MATERIALS AND METHODS: Grade 4 titanium discs were randomly divided into 5 groups and each group was divided into 2 subgroups, with one contaminated with Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans), and the other contaminated with Porphyromonas gingivalis (P. gingivalis). Group 1 did not receive bacterial inoculation or surface debridement and served as a control. Group 2 received A. actinomycetemcomitans or P. gingivalis inoculation, separately. Group 3 received bacterial inoculation and titanium curette debridement, followed by normal saline irrigation. Group 4 received bacterial inoculation, curette debridement, normal saline irrigation, and ultrasonication. Group 5 received bacterial inoculation, curette debridement, normal saline irrigation, and placement in 0.12% chlorhexidine. After various surface treatments, the surface roughness and hydrophilicity of the titanium surface were measured, the number of adhered osteoblast cells was calculated, and the amount of residual lipopolysaccharide (LPS) was quantified. RESULTS: A. actinomycetemcomitans and P. gingivalis biofilms noticeably reduced surface hydrophilicity. Groups 3-5 showed decreased hydrophilicity and fewer adhered osteoblast cells compared with the control group. Although ultrasonication was more effective in removing LPS than curette debridement and chlorhexidine, cell adhesion was not as high as with clean titanium discs. CONCLUSIONS: The non-surgical treatment used in this study was not effective in removing LPS from titanium surfaces and increasing osteoblast adhesion. A more effective method to remove LPS completely is required to enhance the treatment outcome of peri-implantitis.

Comparison of the adhesion of Streptococcus sanguinis to commonly used dental alloys stratified by gold content.

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.

Controlled-release of tetracycline and lovastatin by poly(D,L-lactide-co-glycolide acid)-chitosan nanoparticles enhances periodontal regeneration in dogs.

Chronic periodontitis is characterized by inflammation of periodontal tissues, leading to bone resorption and tooth loss. The goal of treatment is to regenerate periodontal tissues including bone and cementum lost as a consequence of disease. The local delivery of tetracycline was proven to be effective in controlling localized periodontal infection without apparent side effects. Previous studies suggested that lovastatin has a significant role in new bone formation; however, the local delivery of lovastatin might enhance its therapeutic effects. A number of local delivery devices have been developed recently, including poly(D,L-lactide-co-glycolide acid) (PLGA) nanoparticles. The aim of this study was to develop a local delivery device, PLGA-lovastatin-chitosan-tetracycline nanoparticles, which allows the sequential release of tetracycline and lovastatin to effectively control local infection and promote bone regeneration in periodontitis. The size and microstructure of nanoparticles were examined by transmission electron microscopy, Nanoparticle Size Analyzer, and Fourier transform infrared spectroscopy. The release of tetracycline and lovastatin was quantified using a UV-Vis spectrophotometer. Furthermore, the cytotoxic effect and alkaline phosphatase activity of the nanoparticles in osteoblast cell cultures as well as antibacterial activity against periodontal pathogens were investigated. Finally, the bone regeneration potential of PLGA nanoparticles in three-walled defects in beagle dogs was investigated. The results indicated that PLGA-lovastatin-chitosan-tetracycline nanoparticles showed good biocompatibility, antibacterial activity, and increased alkaline phosphatase activity. The volumetric analysis from micro-CT revealed significantly increased new bone formation in defects filled with nanoparticles in dogs. This novel local delivery device might be useful as an adjunctive treatment in periodontal regenerative therapy.

A functional chitosan membrane with grafted epigallocatechin-3-gallate and lovastatin enhances periodontal tissue regeneration in dogs.

Currently used guided tissue regeneration (GTR) membranes are mainly used as a barrier to prevent epithelial cells growth into defects before new bone formation. The aim of this study was to develop a tri-layer functional chitosan (CS) membrane with epigallocatechin-3-gallate (EGCG) grafted on the outer layer for bactericidal activity, and lovastatin was included in the middle layer for controlled release. Successful EGCG grafting was demonstrated using Fourier transform infrared spectroscopy and EGCG grafting significantly enhanced adhesion and proliferation of human gingival fibroblasts. The release duration of lovastatin reached 21days. CS-Lovastatin1 produced the highest alkaline phosphatase activity and EGCG14-CS exhibited the best bactericidal activity against periodontopathic bacteria. Finally, the EGCG14-CS-Lovastatin1 membrane showed a higher percentage of bone regeneration than BioMend(®) and control groups in one-walled defects of beagle dogs. These results suggest that the EGCG14-CS-Lovastatin1 membrane has the potential to be used as a novel GTR membrane.

Eikenella corrodens in subgingival plaque: relationship to age and periodontal condition.

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%), 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.

Possible periodontal pathogens associated with clinical symptoms of periodontal disease in Japanese high school students.

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 0.83% +/- 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.

The evaluation of Chinese herbal medicine effectiveness on periodontal pathogens.

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.

Deriving fast setting properties of tetracalcium phosphate/dicalcium phosphate anhydrous bone cement with nanocrystallites on the reactant surfaces.

OBJECTIVE: This study attempts to reveal how nanocrystallites on the ceramic surfaces of non-dispersive calcium phosphate cement (nd-CPC) participate in setting processes as compared with conventional CPC (c-CPC). METHODS: The compositions and morphologies of CPC during the early setting reactions were studied with X-ray diffraction and a scanning transmission electron microscope equipped with an energy dispersive spectroscopy system. The pH values and dispersive properties of CPC during the early setting reactions were investigated as well as the compressive strength of nd-CPC after 24h of immersion with varying liquid to powder ratios. RESULTS: The mechanical strength of nd-CPC was approximately 60MPa after a 24h immersion in simulate body solution with a P/L ratio between 3.3 and 4.2g/mL. The nanocrystallites on the particle surfaces of nd-CPC were shown to grow rapidly and provided interlocking sites that allowed rapid development of the apatite phase in the cement, and were also shown to be non-dispersive in solution as determined by an injection test of c-CPC. CONCLUSIONS: The interlocking particles produced by whisker growth on the ceramic particles or new crystallites formed between the ceramic particles caused the cement to be non-dispersive in solution. The particles of reactants with nanocrystallites on surfaces also gave this cement the ability to be shaped easily as a paste during an operation or to be injected into a cavity.

Bactericidal effects of different laser wavelengths on periodontopathic germs in photodynamic therapy.

This study was an attempt to clarify whether the bactericidal effects of photodynamic therapy (PDT) are wavelength or dose-dependent. We also attempted to create an optimised protocol for a light-based bactericidal modality to eliminate periodontal pathogens. Cultures of Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum, Porphromonas gingivalis, Prevotella intermedia, and Streptococcus sanguis, were exposed to a He-Ne laser (632.8 nm) with a 30 mW power output, a 100 mW diode laser at 665 nm, or a 100 mW diode laser at 830 nm, in the presence or absence of methylene blue (MB) as a photosensitiser. A control group was also used with exposure to MB alone without laser exposure. The cultures were analysed by viable counts. The results indicated that exposure to the 100 mW laser light could eliminate up to 40% of bacteria on average. In particular, the most effective killing occurred with exposure to laser light in combination with the MB photosensitiser. The results of kinetic studies indicated that the best PDT response rate was achieved with a 60 s (energy density 21.2 J/cm(2)) exposure to the 665 nm wavelength diode laser in the presence photosensitiser. In this condition, approximately 95% of A. actinomycetemcomitans and F. nucleatum, and 99-100% of the black-pigmented bacteria ( P. gingivalis and P. intermedia) and S. sanguis were eliminated. These results showed that both wavelength and energy density are important factors, and that a low power laser of optimal wavelength and dosage, in combination with an appropriate photosensitiser, is a practical bactericidal modality. We concluded that using a diode laser of proper power and wavelength to deliver 60 s of irradiation could be a useful adjunct with mechanical debridement in the prevention of the re-colonisation of subgingival lesions by pathogenic microorganisms.

Determination of eight selected periodontal pathogens in the subgingival plaque of maxillary first molars in Japanese school children aged 8-11 years.

To prevent the onset or progression of periodontitis, we must understand when periodontal pathogens are first harbored and how they develop the biofilm that causes periodontal disease. The purpose of this study was to determine the relationship between clinical status and selected periodontal pathogens in subgingival plaque in school children. This study was conducted with 95 school children, 8-11 years old. The presence and distribution of eight selected periodontal pathogens sampled from the maxillary right first molar were determined by an indirect immunofluorescent technique and compared with clinical parameters. Of the 95 sites sampled, only one site had all eight pathogens and five sites did not have any of the eight pathogens. The mean number of positive pathogens per site was 3.5 +/- 1.8 and mean percentage of positive pathogens was 3.82 +/- 4.22%. The number and total percentage of positive pathogens were strongly correlated with the Plaque Index (PI). In addition, the number of positive pathogens was correlated to the presence of subgingival calculus. The most frequently found pathogens were Campylobacter rectus (84.2%) and Eikenella corrodens (83.2%), and the least, Actinobacillus actinomycetemcomitans serotype c (7.4%). Of the eight pathogens, the frequency and distribution of Porphyromonas gingivalis were significantly correlated with PI and the presence of calculus. In addition, seven sites with both P. gingivalis and Bacteroides forsythus showed a correlation with gingival inflammation. In conclusion, the presence of P. gingivalis or P. gingivalis and B. forsythus may be a risk marker to be sought in screening for the onset of periodontal disease.