Diagnostic testing as a supportive measure of treatment strategy

Identification of root canal microbiota profiles of periapical tissue diseases using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

OBJECTIVES

The purpose of this study was to identify microorganisms isolated from various periapical tissue diseases using Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF-MS) and classify them via an unsupervised machine learning approach.

METHODS

A total of 150 patients with various apical conditions and teeth in need of endodontic retreatment were divided into five groups, including Retreatment, Acute Apical Abscess, Chronic Apical Abscess, Acute Apical Periodontitis, and Chronic Apical Periodontitis. Samples were collected from root canals using paper points after agitating with a #10 K file then microorganisms were identified using MALDI-TOF-MS. Data were analyzed using a hierarchical clustering method. Quadruple clusters and dendrograms were formed according to similarities and dissimilarities.

RESULTS

A total of 80 species were identified representative of six different phyla. The most similar microorganism species identified were: ''Enterococcus faecalis'' between 21 and 23-year-old female cases in Retreatment group; ''Lactobacillus rhamnosus'' between 20 and 18-year-old male cases in Symptomatic Apical Abscess cases; ''Lactobacillus paracasei'' between 26 and 40-year-old male cases in Asymptomatic Apical Abscess cases; ''Enterococcus faecalis'' between 48 and 50-year-old female cases in Symptomatic Apical Periodontitis cases; ''Lactobacillus rhamnosus'' between 48 and 60-year-old male cases in Asymptomatic Apical Periodontitis cases.

CONCLUSIONS

MALDI-TOF MS can be considered a fast and high-throughput screening technique for microbial species identification in endodontics. Thus, it will provide valuable data for future research designs regarding periapical tissue diseases. As the MALDI-TOF MS database expands and comprehensive data becomes available, the relationship between microbial profiles and disease progression will become increasingly apparent.

The use of computer-assisted FACE for minimal-invasive caries excavation

OBJECTIVES

Caries excavation is still a demanding procedure today. In the past years, methods using light-induced fluorescence have proven their ability to detect bacteria remaining in the tooth's hard tissues. However, methods to control the complete removal of infected dentine have not yet been validated. The aim of the present study was to evaluate the degree of dentine removal during caries excavation using a camera- and software-based device as a guide for fluorescence-aided caries excavation (FACE) in comparison to visual-tactile inspection and a dye-staining method.

MATERIALS AND METHODS

One hundred teeth with carious lesions (C3) were randomly allocated to four groups and excavated with the respective method as primary excavation control method. When the first method indicated complete caries excavation, a second method was used to affirm this. Subsequently, dentine samples were taken to determine residual contamination using PCR. After embedding and sectioning the teeth dentine, microhardness was measured perpendicular to the cavity floor.

RESULTS

By using the camera- and software-based device, 94 % of the cavities tested were free of bacterial contamination. All cavities excavated with the dye-staining or visual-tactile control method were free of bacterial contamination but resulted in a significantly higher dentine removal.

CONCLUSION

The camera- and software-assisted caries excavation seems to be an adequate method to remove contaminated dentine without removing affected dentine.

CLINICAL RELEVANCE

Beside its original application to monitor carious, the device is safe, effective, and easy to use for guided caries excavation and is of worth for both everyday practice and undergraduate education.

A combination of clinical and microbiological management of generalized aggressive periodontitis in primary teeth. A case report

BACKGROUND

Generalized aggressive periodontitis (GAP) in primary teeth is a rare periodontal disease that occurs during or soon after eruption of the primary teeth. An association with systemic diseases is a possibility.

CASE REPORT

A 4-year-old Brazilian girl presented with GAP involving the entire primary dentition. The patient and her parents and sister were subjected to microbiological testing to identify the microorganisms involved in the disease. The patient underwent tooth extraction to eradicate the disease and received a prosthesis for the restoration of masticatory function. After the permanent teeth erupted, fixed orthodontic appliances were place to restore dental arch form and occlusion.

CONCLUSIONS

The results show the importance of an early diagnosis of GAP and of a multidisciplinary approach involving laboratory and clinical management to treat the disease and to restore masticatory function, providing a better quality of life for patients.

Classification of root canal microorganisms using electronic-nose and discriminant analysis

BACKGROUND

Root canal treatment is a debridement process which disrupts and removes entire microorganisms from the root canal system. Identification of microorganisms may help clinicians decide on treatment alternatives such as using different irrigants, intracanal medicaments and antibiotics. However, the difficulty in cultivation and the complexity in isolation of predominant anaerobic microorganisms make clinicians resort to empirical medical treatments. For this reason, identification of microorganisms is not a routinely used procedure in root canal treatment. In this study, we aimed at classifying 7 different standard microorganism strains which are frequently seen in root canal infections, using odor data collected using an electronic nose instrument.

METHOD

Our microorganism odor data set consisted of 5 repeated samples from 7 different classes at 4 concentration levels. For each concentration, 35 samples were classified using 3 different discriminant analysis methods. In order to determine an optimal setting for using electronic-nose in such an application, we have tried 3 different approaches in evaluating sensor responses. Moreover, we have used 3 different sensor baseline values in normalizing sensor responses. Since the number of sensors is relatively large compared to sample size, we have also investigated the influence of two different dimension reduction methods on classification performance.

RESULTS

We have found that quadratic type discriminant analysis outperforms other varieties of this method. We have also observed that classification performance decreases as the concentration decreases. Among different baseline values used for pre-processing the sensor responses, the model where the minimum values of sensor readings in the sample were accepted as the baseline yields better classification performance. Corresponding to this optimal choice of baseline value, we have noted that among different sensor response model and feature reduction method combinations, the difference model with standard deviation based dimension reduction or normalized fractional difference model with principal component analysis based dimension reduction results in the best overall performance across different concentrations.

CONCLUSION

Our results reveal that the electronic nose technology is a promising and convenient alternative for classifying microorganisms that cause root canal infections. With our comprehensive approach, we have also determined optimal settings to obtain higher classification performance using this technology and discriminant analysis.

Resistance to tetracycline and β-lactams and distribution of resistance markers in enteric microorganisms and pseudomonads isolated from the oral cavity

This study evaluated the occurrence of enteric bacteria and pseudomonads resistant to tetracycline and β-lactams in the oral cavity of patients exhibiting gingivitis (n=89), periodontitis (n=79), periodontally healthy (n=50) and wearing complete dentures (n=41). Microbial identification and presence of resistance markers associated with the production of β-lactamases and tetracycline resistance were performed by using biochemical tests and PCR. Susceptibility tests were carried out in 201 isolates of enteric cocci and rods. Resistance to ampicillin, amoxicillin/clavulanic acid, imipenem, meropenem and tetracycline was detected in 57.4%, 34.6%, 2.4%, 1.9% and 36.5% of the isolates, respectively. β-lactamase production was observed in 41.2% of tested microorganisms, while the most commonly found β-lactamase genetic determinant was gene blaTEM. Tetracycline resistance was disseminated and a wide scope of tet genes were detected in all studied microbial genus.

Occurrence of yeasts, enterococci and other enteric bacteria in subgingival biofilm of HIV-positive patients with chronic gingivitis and necrotizing periodontitis

The purpose of this study was to determine the prevalence of enteric bacteria and yeasts in biofilm of 80 HIV-positive patients with plaque-associated gingivitis or necrotizing periodontitis. Patients were subjected to extra, intra oral and radiographic examinations. The oral hygiene, bleeding on probing, gingival conditions, and attachment loss were evaluated. Clinical specimens were collected from gingival crevices or periodontal pockets, transferred to VMGA III, diluted and transferred to Sabouraud Dextrose agar with 100 μg/ml of chloramphenicol, peptone water, EVA broth, EMB agar, SS agar, Bile esculin agar and Brilliant green agar. Isolation of yeasts was carried out at room temperature, for 3-7 days; and for the isolation of enteric microorganisms plates were incubated at 37°C, for 24-48 h. The yeasts identification was performed according to the carbon and nitrogen assimilation, fermentation of carbohydrates and germ tube formation. Bacteria were identified according to their colonial and cellular morphologies and biochemical tests. Yeasts were identified as Candida albicans and its occurrence was more common in patients with CD4+ below 200/mm³ and was affected by the extension of periodontal involvement (P = 0.0345). Enteric bacteria recovered from clinical specimens were identified as Enterobacter sakazakii, Enterobacter cloacae, Serratia liquefaciens, Klebsiella oxytoca and Enterococcus sp. Enterobacteriaceae and enterococci were detected in 32.5% of clinical samples from patients with necrotizing periodontitis. In conclusion, non-oral pathogenic bacteria and C. albicans were more prevalent in periodontal sites of HIV-positive patients with necrotizing periodontitis and chronic gingivitis.

Carpegen�real-time polymerase chain reaction vs. anaerobic culture for periodontal pathogen identification

BACKGROUND/AIMS

The aim of this study was to compare two methods of microbiological diagnosis, anaerobic bacterial culture and real-time polymerase chain reaction (PCR), for the detection of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, Fusobacterium nucleatum, and Treponema denticola.

METHODS

Seventy-two samples were collected from 18 patients who were suffering from aggressive periodontitis. The data obtained were compared for the two methods.

RESULTS

The results obtained with real-time PCR were different from those obtained with bacterial culture. The detection differences were 3% for A. actinomycetemcomitans, 8.33% for P. intermedia, and 12.5% for F. nucleatum. However, the differences for P. gingivalis and T. forsythia were 51.39% and 36.11%, respectively. No comparison was possible for T. denticola because it cannot be identified in culture. The variations found were the result of the better detection level (10(2) pathogens) of the PCR probe. Unlike bacterial culture, PCR allows the detection of T. denticola, which does not forming colonies and is oxygen sensitive. For F. nucleatum, T. forsythia and P. gingivalis, the real-time PCR technique was more sensitive than culture.

CONCLUSION

Good results were obtained with the real-time PCR technique for the six periopathogens targeted. This method seems to be indicated for its simplicity, rapidity and reproducibility but it cannot analyze data for an antibiotic susceptibility test. The periodontist must therefore choose one of these two methods according to his specific clinical objective: to obtain rapid, specific detection even with weak initial concentrations (but for targeted periopathogens only) or to be non-specific and analyze the pathological activity with an antibiogram.

Tuned-aperture computed tomography for detection of induced mid-buccal/lingual alveolar bone defects

BACKGROUND

The detection of bone loss in mid-buccal and lingual crests is impossible using conventional radiographs because of the superimposition of overlying anatomy and lack of three-dimensional information. The purpose of this study was to compare the diagnostic efficacy of tuned-aperture computed tomography (TACT) and conventional two-dimensional direct digital radiography (DDR) in an in vitro environment.

METHODS

A total of 45 mandibular molars had 0.8-mm lesions on mid-buccal/lingual crestal areas. Half of the sites received defects, whereas the other half served as controls. Nine DDR images were used to generate TACT slices that were further subjected to iterative restoration (TACT-IR). Eight observers used a confidence rating scale to record diagnoses. Receiver operating characteristic (ROC) analysis was done, and areas under the curves were computed (A(z)) as indicators of diagnostic accuracy. Analysis of variance (ANOVA) was used to test for effects of observer, imaging modality, and location on the detection of lesions.

RESULTS

TACT-IR performed significantly better than DDR. There was a significant difference in the accuracy of diagnosis based on observers (P <0.001).

CONCLUSION

TACT-IR appears to be the imaging modality of choice for the detection of small osseous changes on crestal bone in mid-buccal/lingual sites.

Variabilité de l'efficacité de l'érythromycine et de la spiramycine sur les pathogènes parodontaux dans les parodontites agressives. Étude in vitro comparative

AIMS

Erythromycin (ERY) and spiramycin (SPI) are the most frequently prescribed macrolides by dentists. However, the emergence of resistant anaerobic subgingival bacteria imposes an increased vigilance. This study aims to compare these macrolides efficacy on principal periopathogens.

MATERIALS AND METHODS

Twenty adult patients with aggressive periodontitis were selected and a total of 60 samples were taken from subgingival flora. Bacterial strains of Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, Fusobacterium nucleatum, Peptostreptococcus micros and Actinobacillus actinomycetemcomitans were isolated according to J. Slots's rapid identification method. The susceptibilities to ERY and SPI were studied using disk diffusion susceptibility test and minimum inhibitory concentration test (MIC test).

RESULTS

The efficiency variability of ERY and SPI on the 50 isolated anaerobic periopathogens was present either interindividually (between different patients) and intra-individually (within the same patient). While 68% of the tested anaerobic bacteria were sensitive to SPI (22% resistant), only 54% were sensitive to ERY (34% resistant). Although moderate, the efficacy of SPI seemed more regular in general than ERY: it's variation coefficient (40%) is lower than the ERY one (53%). The 7 A. actinomycetemcomitans tested showed all a high resistance.

CONCLUSION

In a general way, the spectre of activity of SPI is stacked in that of ERY. However, this study shows a better and regular activity of SPI on the main tested periopathogens. These results are in favour of the use of SPI in periodontology when penicillins and doxycycline are not useful because specific problems are identified (allergy, pregnancy...).

Antimicrobial susceptibility variation of 50 anaerobic periopathogens in aggressive periodontitis: an interindividual variability study

BACKGROUND/AIMS

The frequent use of antibiotics in developed countries has led to the emergence of widespread bacterial resistance. In this study, the interindividual variability of the antibiotic susceptibility of 50 putative microorganisms in aggressive periodontitis patients has been evaluated by means of VC (variation coefficient).

MATERIAL AND METHODS

A total of 60 microbial samples were collected from 20 adult patients diagnosed with aggressive periodontitis (2-4 samples by patient). Bacterial strains of Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, Fusobacterium nucleatum, and Peptostreptococcus micros were isolated according to Slots' rapid identification method. The susceptibilities to 10 antibiotics were studied: penicillin G (PEN), ampicillin (AMP), amoxicillin (AMX), amoxicillin/clavulanate (AMC), tetracycline (TET), doxycycline (DOX), ciprofloxacin (CIP), erythromycin (ERY), spiramycin (SPI) and clindamycin (CLIN), using the Disk Diffusion Susceptibility test (DDS test: Kirby-Bauer's modified method for anaerobic bacteria). The broth microdilution Minimum Inhibitory Concentration test was carried out as a control test.

RESULTS

Among the 50 identified bacteria, 15 were P. gingivalis, 12 P. intermedia, 8 T. forsythia, 9 F. nucleatum, and 6 P. micros. The results of the DDS test show that penicillins (especially AMC, AMP, and AMX), cyclines (especially DOX) and CLIN are highly effective against the 50 anaerobic studied bacteria. CIP and ERY have the lowest efficacy against those bacteria. CIP shows a very variable activity according to anaerobic bacteria species, being particularly inactive against P. gingivalis and very efficient against T. forsythia and P. micros. SPI is also highly efficient but not against P. micros.

CONCLUSIONS

The interindividual susceptibility of principal periodontal pathogens to antibiotics is not homogeneous and seems to vary according to bacterial species and antimicrobial molecules. This variability seems to be greater with older molecules (PEN, TET, ERY) than with more recent ones, which indicates more stable results (AMC, AMX, AMP, and DOX). P. intermedia appeared to be the bacteria most resistant to penicillins and showed the highest coefficient variation. Together with scaling and root planing, the combination of two antibiotics would therefore seem to be recommended in the treatment of aggressive periodontitis, particularly in the presence of P. intermedia.

Exploiting Molecular Methods to Explore Endodontic Infections: Part 1—Current Molecular Technologies for Microbiological Diagnosis

Endodontic infections have been traditionally studied by culture-dependent methods. However, as with other areas of clinical microbiology, culture-based investigations are plagued by significant problems, including the probable involvement of viable but uncultivable micro-organisms with disease causation and inaccurate microbial identification. Innumerous molecular technologies have been used for microbiological diagnosis in clinical microbiology, but only recently some of these techniques have been applied in endodontic microbiology research. This paper intended to review the main molecular methods that have been used or have the potential to be used in the study of endodontic infections. Moreover, advantages and limitations of current molecular techniques when compared to conventional methods for microbial identification are also discussed.