Lesiones perirradiculares persistentes: revisión narrativa / Persistent periradicular lesions: a narrative review

La persistencia de lesiones perirradiculares luego del tra- tamiento endodóntico es un problema que requiere del clínico un conocimiento cabal de la histofisiología y de la histopato- logía del sistema de conductos radiculares del tejido pulpar y de los tejidos perirradiculares (periodonto y hueso); además de considerar siempre la posible existencia de enfermedades sistémicas que también pueden actuar como factores de in- fluencia. La presencia de bacterias remanentes a posteriori del tratamiento es considerada como una de las causas principales y más frecuentes para la perpetuación de las lesiones perirra- diculares. Sin embargo, existen otros factores causales, como la existencia de conductos laterales o accesorios infectados y no tratados, la reabsorción dentinaria interna, intercomunica- ciones, cul-de-sacs o istmos; que representan áreas de difícil acceso durante la instrumentación e irrigación. Cuando la cau- sa original se localiza en la zona perirradicular, como en los casos de actinomicosis, reacciones a cuerpo extraño, cristales de colesterol (CRCo) y granulomas o quistes con alto conte- nido de CRCo, la indicación más adecuada es el retratamiento y la cirugía periapical como complemento (AU)

The persistence of periradicular lesions after endodontic treatment is a problem that requires the doctor to have a thor- ough knowledge of the histophysiology and histopathology of the root canal system, the pulp tissue and periradicular tis- sues (periodontium and bone); as well as always considering the possible existence of systemic alterations that can also be influencing factors. Persisting bacteria within the root canal system after treatment is one of the major and most frequent causes for the perpetuation of periradicular lesions. Howev- er, there are other possible causal factors such as the exist- ence of untreated lateral or accessory canals, internal dentin resorption, intercommunications, cul-de-sacs or isthmuses; areas that represent a difficulty in access during instrumen- tation and irrigation. If the original cause is located in the periradicular area, in cases like actinomycosis, foreign-body reactions, cholesterol crystals (CRCo) and granulomas or cysts with high content of CRCo, retreatment coupled with periapical surgery is the best approach to treatment (AU)

Centipeda periodontii in human periodontitis.

This study assessed the subgingival occurrence of the flagellated, Gram-negative, anaerobic rod Centipeda periodontii in chronic periodontitis and periodontal health/gingivitis with species-specific nucleic acid probes, and evaluated the in vitro resistance of subgingival isolates to therapeutic levels of amoxicillin, metronidazole, and doxycycline. Subgingival plaque biofilm specimens from 307 adults with chronic periodontitis, and 48 adults with periodontal health/localized gingivitis, were evaluated with digoxigenin-labeled, whole-chromosomal, DNA probes to C. periodontii ATCC 35019 possessing a 10(4) cell detection threshold. Fifty-two C. periodontii subgingival culture isolates were assessed on antibiotic-supplemented enriched Brucella blood agar for in vitro resistance to either amoxicillin at 2 µg/ml, metronidazole at 4 µg/ml, or doxycycline at 2 µg/ml. A significantly greater subgingival occurrence of C. periodontii was found in chronic periodontitis subjects as compared to individuals with periodontal health/gingivitis (13.4 vs. 0 %, P < 0.003), although high subgingival counts of the organism (≥ 10(6) cells) were rarely detected (1.3 % of chronic periodontitis subjects). In vitro resistance was not found to amoxicillin or metronidazole, and to doxycycline in only 2 (3.9 %) of the 52 C. periodontii clinical isolates studied. These findings indicate that C. periodontii is not a major constituent of the subgingival microbiome in chronic periodontitis or periodontal health/gingivitis. The potential contribution of C. periodontii to periodontal breakdown in the few chronic periodontitis subjects who yielded high subgingival levels of the organism remains to be delineated. C. periodontii clinical isolates were susceptible in vitro to therapeutic concentrations of three antibiotics frequently used in treatment of human periodontitis.

The phylum Synergistetes in gingivitis and necrotizing ulcerative gingivitis.

The clinical manifestation of necrotizing ulcerative gingivitis (NUG) is distinct from that of common gingivitis in that it is characterized by local necrosis of the gingival tissues, rapid onset, pain and extensive bleeding. The phylum Synergistetes is a novel bacterial phylum consisting of Gram-negative anaerobes, with evidence of presence in biofilms associated with periodontal and endodontic infections. To date, the involvement of members of this phylum in NUG has not been investigated. This study aimed to evaluate the presence and levels of known human oral Synergistetes bacterial clusters in dental plaque from patients with NUG and compare them with those found in gingivitis. Marginal dental plaque samples from 21 NUG and 21 gingivitis patients were analysed quantitatively by fluorescent in situ hybridization and microscopy for members of two oral Synergistetes clusters (A and B) and for Jonquetella anthropi. Synergistetes cluster A bacteria were detected in all samples but at higher levels (9.4-fold) and proportions (2.5-fold) in NUG patients than in gingivitis patients. However, with regard to Synergistetes cluster B bacteria, there were no differences between NUG and gingivitis patients. J. anthropi was detected in only half of the samples and at lower levels than the other taxa. In conclusion, these data demonstrate that Synergistetes cluster A bacteria, but not cluster B bacteria or J. anthropi, are more strongly associated with NUG than with gingivitis.

Insights into the virulence of oral biofilms: discoveries from proteomics.

This review covers developments in the study of polymicrobial communities, biofilms and selected areas of host response relevant to dental plaque and related areas of oral biology. The emphasis is on recent studies in which proteomic methods, particularly those using mass spectrometry as a readout, have played a major role in the investigation. The last 5-10 years have seen a transition of such methods from the periphery of oral biology to the mainstream, as in other areas of biomedical science. For reasons of focus and space, the authors do not discuss biomarker studies relevant to improved diagnostics for oral health, as this literature is rather substantial in its own right and deserves a separate treatment. Here, global gene regulation studies of plaque-component organisms, biofilm formation, multispecies interactions and host-microbe interactions are discussed. Several aspects of proteomics methodology that are relevant to the studies of multispecies systems are commented upon.

Amniotic fluid interleukin-1 beta and interleukin-6, but not interleukin-8 correlate with microbial invasion of the amniotic cavity in preterm labor.

PROBLEM: We compared the frequency of intra-amniotic infection in preterm labor (PL) with women not in labor, and correlated infection with amniotic fluid (AF) cytokines. Detailed identification of species, especially mycoplasmata, was tried to improve our understanding of the pathogenesis of PL. METHOD OF STUDY: AF from 20 women with PL and 20 controls were evaluated. Infection was detected by PCR for Mycoplasma hominis, Ureaplasma urealyticum and 16S rRNA bacterial gene, which was cloned and sequenced for bacterial identification. Interleukin (IL)-1ß, IL-6, IL-8 and tumor necrosis factor (TNF)-α levels were measured by ELISA. RESULTS: Frequency of intra-amniotic infection is higher in PL (40.0%). Sequencing-based method identified Bacteroides fragilis, Prevotella bivia and Leptotrichia amnionii, in addition to Mycoplasma species detected by PCR. AF infection correlated with increased IL-1ß and IL-6 levels. CONCLUSION: The frequency of intra-amniotic infection, especially M. hominis, in PL women who delivered with 7 days, is high and correlates with high IL-1ß and IL-6 levels, but not IL-8.

Asociación de Aggregatibacter actinomycetemcomitans y microorganismos del complejo rojo con parámetros clínicos de pacientes con periodontitis crónica / Association of Aggregatibacter actinomycetemcomitans and red complex microorganisms with clinical parameters of patients with chronic periodontitis

Fundamento: en Latinoamérica se ha estudiado muy poco la asociación entre Aggregatibacter actinomycetemcomitans y microorganismos del complejo rojo con los parámetros clínicos de pacientes con periodontitis crónica. Objetivo: identificar la presencia de Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis y Tanerella forsythia en pacientes con periodontitis crónica, y establecer su asociación con parámetros clínicos y hábito de fumar. Método: se examinaron los parámetros clínicos (profundidad de bolsa, nivel de inserción, sangrado al sondaje, índice de placa y supuración) y la presencia de periodontopatógenosen 76 pacientes con periodontitis crónica en Medellín, Colombia. Las muestras subgingivales se procesaron mediante cultivo. Para determinar las diferencias de las variables clínicas y el hábito de fumar con la presencia o ausencia de periodontopatógenos se utilizaron pruebas de chi cuadrado y U de Mann-Whitney (P< 0.05). Resultados: se encontró A. actinomycetemcomitans, P. gingivalis y T. forsythia en el 23.7 porciento, 64.4 porciento y 40.8 porciento de los pacientes respectivamente. Los sujetos que presentaron A. actinomycetemcomitans y P. gingivalis mostraron peores parámetros clínicos, diferencias que fueron altamente significativas (P<0.0001). T. forsythia se asoció significativamente con mayor profundidad de sondaje (P=0.02), presencia de sangrado (P<0.0001) y placa bacteriana (P<0.0001). Se observó una asociación altamente significativa entre hábito de fumar y presencia de A. actinomycetemcomitans y P. gingivalis (P<0.0001). Conclusiones: P. gingivalis, T. forsythia y A. actinomycetemcomitans se asociaron con condiciones periodontales adversas. Es importante realizar exámenes microbiológicos de las poblaciones con periodontitis debido a que la composición particular de la placa subgingival puede determinar un adecuado tratamiento periodontal.

Background: the association between Aggregatibacter actinomycetemcomitans and red complex microorganisms with clinical parameters of patients with chronic periodontitis has been studied very little in Latin America. Objective: to identify the presence of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis and Tanerella forsythia in patients with chronic periodontitis, and establish their association with clinical parameters and smoking. Method: we examined clinical parameters (probing depth, attachment level, bleeding on probing, suppuration and plaque index) and the presence of periodontal pathogens in 76 patients with chronic periodontitis in Medellín, Colombia. Subgingival samples were processed by culture. Chi square and Mann-Whitney test were used to determine differences in clinical variables and smoking in the presence or absence of periodontal pathogens (P<0.05). Results: We found A. actinomycetemcomitans, P. gingivalis and T. forsythia in 23.7 percent, 64.4 percent and 40.8 percent of patients respectively. Patients whit A. actinomycetemcomitans and P. gingivalis showed worse clinical parameters, differences were highly significant (P<0.0001). T. forsythia was associated with significantly higher probing depth (P= 0.02), presence of bleeding (P<0.0001) and plaque (P<0.0001). There was a highly significant association between smoking and presence of A. actinomycetemcomitans and P. gingivalis (P<0.0001). Conclusions: P. gingivalis, T. forsythia and A. actinomycetemcomitans were associated with adverse periodontal conditions. It is important to conduct microbiological tests on populations with periodontitis because the particular composition of subgingival plaque determines an appropriate periodontal treatment.

Asociación de Aggregatibacter actinomycetemcomitans y microorganismos del complejo rojo con parámetros clínicos de pacientes con periodontitis crónica / Association of Aggregatibacter actinomycetemcomitans and red complex microorganisms with clinical parameters of patients with chronic periodontitis

Fundamento: en Latinoamérica se ha estudiado muy poco la asociación entre Aggregatibacter actinomycetemcomitans y microorganismos del complejo rojo con los parámetros clínicos de pacientes con periodontitis crónica. Objetivo: identificar la presencia de Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis y Tanerella forsythia en pacientes con periodontitis crónica, y establecer su asociación con parámetros clínicos y hábito de fumar. Método: se examinaron los parámetros clínicos (profundidad de bolsa, nivel de inserción, sangrado al sondaje, índice de placa y supuración) y la presencia de periodontopatógenosen 76 pacientes con periodontitis crónica en Medellín, Colombia. Las muestras subgingivales se procesaron mediante cultivo. Para determinar las diferencias de las variables clínicas y el hábito de fumar con la presencia o ausencia de periodontopatógenos se utilizaron pruebas de chi cuadrado y U de Mann-Whitney (P< 0.05). Resultados: se encontró A. actinomycetemcomitans, P. gingivalis y T. forsythia en el 23.7 porciento, 64.4 porciento y 40.8 porciento de los pacientes respectivamente. Los sujetos que presentaron A. actinomycetemcomitans y P. gingivalis mostraron peores parámetros clínicos, diferencias que fueron altamente significativas (P<0.0001). T. forsythia se asoció significativamente con mayor profundidad de sondaje (P=0.02), presencia de sangrado (P<0.0001) y placa bacteriana (P<0.0001). Se observó una asociación altamente significativa entre hábito de fumar y presencia de A. actinomycetemcomitans y P. gingivalis (P<0.0001). Conclusiones: P. gingivalis, T. forsythia y A. actinomycetemcomitans se asociaron con condiciones periodontales adversas. Es importante realizar exámenes microbiológicos de las poblaciones con periodontitis debido a que la composición particular de la placa subgingival puede determinar un adecuado tratamiento periodontal(AU)

Background: the association between Aggregatibacter actinomycetemcomitans and red complex microorganisms with clinical parameters of patients with chronic periodontitis has been studied very little in Latin America. Objective: to identify the presence of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis and Tanerella forsythia in patients with chronic periodontitis, and establish their association with clinical parameters and smoking. Method: we examined clinical parameters (probing depth, attachment level, bleeding on probing, suppuration and plaque index) and the presence of periodontal pathogens in 76 patients with chronic periodontitis in Medellín, Colombia. Subgingival samples were processed by culture. Chi square and Mann-Whitney test were used to determine differences in clinical variables and smoking in the presence or absence of periodontal pathogens (P<0.05). Results: We found A. actinomycetemcomitans, P. gingivalis and T. forsythia in 23.7 percent, 64.4 percent and 40.8 percent of patients respectively. Patients whit A. actinomycetemcomitans and P. gingivalis showed worse clinical parameters, differences were highly significant (P<0.0001). T. forsythia was associated with significantly higher probing depth (P= 0.02), presence of bleeding (P<0.0001) and plaque (P<0.0001). There was a highly significant association between smoking and presence of A. actinomycetemcomitans and P. gingivalis (P<0.0001). Conclusions: P. gingivalis, T. forsythia and A. actinomycetemcomitans were associated with adverse periodontal conditions. It is important to conduct microbiological tests on populations with periodontitis because the particular composition of subgingival plaque determines an appropriate periodontal treatment(AU)

Periodontal disease and preterm birth relationship: a review of the literature.

Despite medical care improves consistently, the rate of preterm birth has risen in recent years. In Italy the rate of preterm birth between the XXXIII and the XXXVI week is 13.5%, while it amounts to 1.3% for preterm birth between XXIV and the XXXII week. Consequently, the identification of risk factors for preterm birth that might be modified would have far-reaching and long-lasting effects. A significant number of preterm birth may be attributed to infections of the urogenital tract, such as bacterial vaginosis. In the last decade, great interest has been generated to support the hypothesis that sub-clinical infection at sites that are also distant from the genito-urinary tract may be an important cause of preterm labour, probably through the activation of abnormal inflammatory responses within the uterus and intrauterine tissues. There is emerging evidence of a possible relationship between maternal periodontal diseases as a potential risk factor of adverse pregnancy outcomes, like preterm low birth weight even though not all of the actual data support such hypothesis. Further studies are clearly required to clarify the causes and/or relationships linking pathologic oral conditions and adverse pregnancy outcomes. So far, from a clinical standpoint, it would appear that the assessment of the periodontal status of pregnant women during an early pregnancy might be useful in providing an important indicator of risk for future obstetric complications.

[Relationships between diabetes mellitus and periodontal disease: current knowledges and therapeutic prospects]. / Rapporti tra il diabete mellito e la malattia parodontale: conoscenze attuali e prospettive terapeutiche.

Diabetes mellitus is a disorder of the endocrine system. An important pathology of dental interest to which the diabetic patient can go encounter, especially if not controlled from the metabolic point of view, is the periodontal disease. The aim of this review is to illustrate the relation between diabetes mellitus and periodontal disease estimating the several therapeutic options on hand in the clinical daily practice. Many studies show an important association between diabetes and the pathogenesis of periodontal disease. Vascular changes caused by hyper-glycemia are associated to the development of periodontal pathogens species. Moreover, diabetics show an exacerbate host response with hyperproduction of inflammatory mediators and polymorphonuclear dysfunction. Diabetics with good metabolic control and patients with good oral hygiene show a reduced risk of periodontitis. In conclusion, diabetes mellitus (of type 1 and type 2) is an important risk factor for periodontitis. Diabetes mellitus determines changes in bacterial population and production of inflammatory mediators, and reduces the efficacy of the host response. Good controlled diabetes do not cause a major risk of periodontitis and improve the results of the periodontal initial therapy and of the eventual surgical therapy. Moreover, periodontal therapy may reduce the request of insulin in diabetics. It is reasonable a reciprocal relation between diabetes and periodontal disease.

Etiology of ventilator-associated pneumonia.

This review focuses on the top ten causes of ventilator-associated pneumonia (VAP), updating an earlier study. These pathogens have specific risk factors, different patterns of clinical resolution, and a wide range of attributable mortality. The discussion herein analyzes these aspects, placing particular emphasis on risk factors, attributable mortality, resistance, and the implications for management.

Nested PCR detection of Centipeda periodontii in primary endodontic infections.

In recent years, molecular genetic methodologies have provided significant additional knowledge about components of the microbiota associated with infections of endodontic origin. Following this research line, the purpose of the present study was to investigate the prevalence of Centipeda periodontii in primary endodontic infections using a species-specific nested PCR assay. Samples were collected from fifty teeth having carious lesions, necrotic pulps, and different forms of periradicular diseases. DNA extracted from the samples was initially amplified using universal 16S rDNA primers, and a second round of amplification used the first PCR products to detect a specific fragment of C. periodontii 16S rDNA. This species was detected in 3 (13%) of 23 asymptomatic cases, in 1 (14%) of 7 cases diagnosed as acute apical periodontitis, and in 3 (15%) of 20 pus samples aspirated from acute periradicular abscesses. There was no significant association between C. periodontii and the presence of clinical symptoms. Overall, C. periodontii was detected in 14% of the cases of endodontic infections. This is probably the hitherto first study to detect C. periodontii in primary endodontic infections. The specific role played by this bacterial species in infections of endodontic origin awaits further clarification.

Are dental diseases examples of ecological catastrophes?

Dental diseases are among the most prevalent and costly diseases affecting industrialized societies, and yet are highly preventable. The microflora of dental plaque biofilms from diseased sites is distinct from that found in health, although the putative pathogens can often be detected in low numbers at normal sites. In dental caries, there is a shift towards community dominance by acidogenic and acid-tolerant Gram-positive bacteria (e.g. mutans streptococci and lactobacilli) at the expense of the acid-sensitive species associated with sound enamel. In contrast, the numbers and proportions of obligately anaerobic bacteria, including Gram-negative proteolytic species, increase in periodontal diseases. Modelling studies using defined consortia of oral bacteria grown in planktonic and biofilm systems have been undertaken to identify environmental factors responsible for driving these deleterious shifts in the plaque microflora. Repeated conditions of low pH (rather than sugar availability per se) selected for mutans streptococci and lactobacilli, while the introduction of novel host proteins and glycoproteins (as occurs during the inflammatory response to plaque), and the concomitant rise in local pH, enriched for Gram-negative anaerobic and asaccharolytic species. These studies emphasized (a). significant properties of dental plaque as both a biofilm and a microbial community, and (b). the dynamic relationship existing between the environment and the composition of the oral microflora. This research resulted in a novel hypothesis (the 'ecological plaque hypothesis') to better describe the relationship between plaque bacteria and the host in health and disease. Implicit in this hypothesis is the concept that disease can be prevented not only by directly inhibiting the putative pathogens, but also by interfering with the environmental factors driving the selection and enrichment of these bacteria. Thus, a more holistic approach can be taken in disease control and management strategies.

Rationale for use of antibiotics in periodontics.

The purpose of this review is to provide the clinician with some practical rationale for the selection and use of antibiotics in the treatment of destructive periodontal diseases. We have attempted to integrate approximately 20 years of periodontal literature describing antibiotic therapy with personal experience and 21st century ideas. This article addresses antibiotic use during treatment of aggressive periodontitis with emphasis on juvenile disease and adult refractory diseases. The literature review revealed few large, controlled studies that compared efficacy of adjunctive antibiotic use to mechanical therapy alone. Even fewer studies evaluated the efficacy of one antibiotic relative to another. However, based on the evidence available, certain conclusions were drawn. Adjunctive use of an antibiotic along with mechanical debridement is recommended for the treatment of Actinobacillus actinomycetemcomitans-associated periodontitis as an acceptable therapeutic regimen. Due to the emergence of tetracycline-resistant A. actinomycetemcomitans, the combination of metronidazole and amoxicillin may be preferable. In aggressive refractory periodontitis, compelling evidence exists that the use of an appropriate adjunctive antibiotic frequently gives a more favorable clinical response than mechanical therapy alone. Unfortunately, the selection of antibiotic is not as clear and is probably case-dependent. Positive responses have been reported with amoxicillin/clavulanic acid, clindamycin, metronidazole, and the combination therapy metronidazole plus amoxicillin. The introduction of local delivery antibiotics specifically for the treatment of periodontitis offers a novel concept for the treatment of localized disease. The latter, in particular, may prove useful in the treatment of recurrent disease activity or where only a few individual sites are involved.

Fecal bacterial activity in symptomatic carbohydrate malabsorption: effect on the fecal short-chain fatty acid ratio.

BACKGROUND: It is still not clear why only some patients with carbohydrate malabsorption experience symptoms. In a previous study on healthy fructose malabsorbers an increased degradation of fructose in anaerobic fecal cultures from symptomatic malabsorbers was found, indicating increased bacterial activity. In the present study, the same investigation was repeated in patients with nonspecific abdominal complaints and fructose malabsorption. Moreover fecal short-chain fatty acids (SCFA), products of colonic bacterial fermentation of carbohydrates were measured. PATIENTS AND METHODS: A standard quantity of fructose (500 mg) was added to anaerobic fecal cultures from 25 patients (nine men, 16 women; median of age 53 years, range 36-69 years). The fructose degradation rate was assessed using photometry, and interpreted as representing bacterial activity in the colon. In 14 of the patients, SCFA levels were also measured using chromatography on a capillary column. RESULTS: 10 of the 25 patients had a history of symptoms after ingesting fructose-containing foods, and also showed symptoms during the test; 6 patients had symptoms either in their history or during the test; and the remaining 9 were free of symptoms. There were no differences in the H2 increase. The fructose degradation rate was higher in symptomatic malabsorbers (255 mg vs. 217 mg), but the difference was not significant. However, there was a strong inverse correlation between this bacterial activity and the acetate level, with r = -0.822 (P = 0.000) and r = -0.868 (P = 0.000) in the rank correlation. The correlation for propionate was r = 0.479 (P = 0.083), and that for butyrate was r = 0.599 (P = 0.024). CONCLUSIONS: This study failed to confirm a significant correlation between fecal bacterial activity and the occurrence of symptoms in patients with fructose malabsorption. However, the interesting correlation with the SCFA raises questions regarding possible connections between colonic bacteria, carbohydrate malabsorption, and the beneficial effect of this pattern of SCFA in several colonic diseases.

Influence of five antianaerobic antibiotics on endotoxin liberation by gram-negative anaerobes.

Endotoxin, a lipopolysaccharide (LPS), has for many years been recognized as a key effector molecule in the pathogenesis of gram-negative sepsis and septic shock. Seven strains of the Bacteroides fragilis group were studied for their ability to liberate endotoxin upon exposure to five anti-anaerobic antibiotics, trovafloxacin, cefoxitin, imipenem, meropenem and piperacillin/tazobactam, in an in-vitro experiment. The minimum inhibitory concentrations (MICs) of the antibiotics were determined by using the broth macrodilution technique. Thereafter, endotoxin liberation was detected in the filtered broth cultures of the anaerobic bacteria by the limulus amebocyte lysate (LAL) assay after exposing the organisms to four different concentrations of the antibiotics in supplemented Brucella broth. Aliquots of the broth cultures were also taken at intervals of 0, 6, 24 and 48 h for viable counts. All seven gram-negative anaerobic bacteria investigated liberated induced cell-free endotoxin in filtered broth culture many times higher than the control. There was noticeable variation in the propensity of some antibiotics to induce endotoxin liberation. At four times the MICs, cefoxitin and piperacillin/tazobactam induced negligible quantities of endotoxin after 48 h exposure, whereas the others induced high levels of endotoxin release. After exposure to all concentrations for 48 h, endotoxin activity in the test system was many times higher with the Bacteroides fragilis sensu stricto than with the rest of the species in the Bacteroides group. To varying degrees, all five antibiotics had the capacity to induce endotoxin liberation by gram-negative anaerobic bacteria. This differential endotoxin release by the B. fragilis group may, in part, explain why B. fragilis sensu stricto, more than the other Bacteroides spp., is usually associated with clinical infections and higher morbidity.

Effect of initial periodontal therapy on the frequency of detecting Bacteroides forsythus, Porphyromonas gingivalis, and Actinobacillus actinomycetemcomitans.

BACKGROUND: Porphyromonas gingivalis, Bacteroides forsythus, and Actinobacillus actinomycetemcomitans have been described as periodontopathic bacteria, and their presence in subgingival pockets can lead to development of periodontal disease. Until now, clinical parameters have been used to evaluate the effect of conventional periodontal treatment without microbiological parameters. The present study examined the microbiological effects of initial periodontal therapy using DNA probes and the polymerase chain reaction (PCR). METHODS: Twenty-six patients with periodontitis, 10 males and 16 females, were given instructions regarding oral hygiene, then thoroughly treated by conventional scaling and root planing. Bacterial samples were collected on paper points from 4 sites per patient at baseline and after initial therapy (total: 104 sites). Clinical parameters including probing depth, attachment level, and bleeding on probing were also recorded for each site at baseline and after therapy. A DNA probe kit was used to monitor the frequency of B. forsythus, P. gingivalis, and A. actinomycetemcomitans, the last of which was identified by PCR. RESULTS: At baseline, B. forsythus was the bacterium most frequently detected. DNA probe analysis also showed that more than half of the sites were colonized by both B. forsythus and P. gingivalis. Initial therapy resulted in significant clinical improvement such as significant reduction in the frequency of B. forsythus and P. gingivalis detected using the DNA probe. A. actinomycetemcomitans was difficult to detect using the DNA probe, but PCR indicated that levels of A. actinomycetemcomitans did not significantly decrease. CONCLUSIONS: These results indicate that initial conventional therapy can eliminate B. forsythus and P. gingivalis, but not A. actinomycetemcomitans. When levels of these bacteria decreased to below-detectable levels, clinical improvement was significant. These results indicate that monitoring levels of these three periodontopathic bacteria may render periodontal therapy more effective and accurate.

Cytotoxic effect of endodontic bacteria on periapical fibroblasts.

This study was conducted to investigate the effects of sonicated bacterial extracts (SBEs) from anaerobic Gram-negative bacteria on periapical fibroblast obtained from the apical portion of human periodontal ligaments. Porphyromonas endodontalis, Porphyromonas gingivalis, Prevotella intermedia, and Fusobacterium nucleatum were chosen from among the endodontic bacteria isolated from root canals having a periapical lesion and compared in terms of their cytotoxicity. The purpose of this study was to examine which bacteria are involved in the development of periapical inflammation. The anaerobes were cultured under strict anaerobic conditions, and the bacterial cells were then harvested by centrifugation after incubation. The concentrated cell suspensions were sonicated and subsequently centrifuged. An SBE was made of each of the filtered supernatants. Each SBE was added to cultures of periapical fibroblasts. The cell growth and proliferation were measured by the MTT method after 3, 5, and 7 days. The SBEs from P. endodontalis, P. gingivalis, and F. nucleatum inhibited the growth of the fibroblasts, whereas the SBE from P. intermedia did not inhibit it. The SBEs from P. gingivalis and F. nucleatum inhibited the fibroblast growth more strongly than did the P. endodontalis, P. gingivalis, and F. nucleatum may participate in the development of periapical lesions.