The role of Candida albicans in root caries biofilms: an RNA-seq analysis

Abstract Objective This study sought to analyze the gene expression of Candida albicans in sound root surface and root caries lesions, exploring its role in root caries pathogenesis. Methodology The differential gene expression of C. albicans and the specific genes related to cariogenic traits were studied in association with samples of biofilm collected from exposed sound root surface (SRS, n=10) and from biofilm and carious dentin of active root carious lesions (RC, n=9). The total microbial RNA was extracted, and the cDNA libraries were prepared and sequenced on the Illumina Hi-Seq2500. Unique reads were mapped to 163 oral microbial reference genomes including two chromosomes of C. albicans SC5314 (14,217 genes). The putative presence of C. albicans was estimated (sum of reads/total number of genes≥1) in each sample. Count data were normalized (using the DESeq method package) to analyze differential gene expression (using the DESeq2R package) applying the Benjamini-Hochberg correction (FDR<0.05). Results Two genes (CaO19.610, FDR=0.009; CaO19.2506, FDR=0.018) were up-regulated on SRS, and their functions are related to biofilm formation. Seven genes ( UTP20 , FDR=0.018; ITR1 , FDR=0.036; DHN6 , FDR=0.046; CaO19.7197 , FDR=0.046; CaO19.7838 , FDR=0.046; STT4 , FDR=0.046; GUT1 , FDR=0.046) were up-regulated on RC and their functions are related to metabolic activity, sugar transport, stress tolerance, invasion and pH regulation. The use of alternative carbon sources, including lactate, and the ability to form hypha may be a unique trait of C. albicans influencing biofilm virulence. Conclusions C. albicans is metabolically active in SRS and RC biofilm, with different roles in health and disease.

Using autofluorescence to detect bacterial contamination in root fractures.

OBJECTIVES: Conventional methods for detecting root fractures cannot assess their depth or bacterial contamination. This study was designed to measure the autofluorescence emitted from a root fracture, with the aim of determining whether this is a suitable method for quantifying the depth and bacterial invasion of a fracture. METHODS: This in vitro study investigated 33 mandibular second molars with periapical lesions that had been extracted after finding root fractures in endodontically treated teeth during intentional replantation or diagnostic surgery. The root fractures were scanned using a fluorescence technique, and the association between fluorescence parameters and fracture depth was analyzed. The significance of the association between the red fluorescence among autofluorescence parameters and bacterial contamination within the fracture was examined. RESULTS: When the depth of the root fractures was evaluated by micro computed tomography, the scattering of light in the fractures increased with depth, and there was a gradual increase in the quantitative fluorescence parameter indicating the deepest point (ΔFmax) in the fractures. In addition, we observed red fluorescence on the outer surface of deeper fractures. The tooth fractures exhibiting red fluorescence were evaluated for bacterial contamination associated with red-fluorescent porphyrin, which revealed bacterial invasion into these fractures. On the other hand, non-red-fluorescing fractures contained necrotic tissue, debris, and irritants. CONCLUSIONS: This viable fluorescent technique can potentially quantify the depth of root fractures and be used as a risk indicator for root fractures with periodontal inflammation. CLINICAL SIGNIFICANCE: The auto-fluorescence technique can be used to detect depth and bacterial contamination of root fractures. It is postulated that the auto-fluorescence can be used as a risk indicator of deep fractures and can replace conventional fracture detection methods.

Effect of Sweeteners on Root Dentine Demineralization Using a Microcosm Biofilm Model / Efecto de los Edulcorantes en la Desmineralización de la Dentina Radicular Utilizando un Modelo de Biofilm Microcosmo

ABSTRACT: The aim of the present study was to evaluate the effect of commercial sweeteners on root dentin demineralization using a microcosm biofilm model. Bovine dentin specimens with pre-determined surface hardness were randomized into six groups according to the studied sweeteners: sucralose, stevia, saccharin, aspartame. Sucrose was used as a positive control and an untreated group as a negative control. The specimens were submitted to biofilm development from one saliva donor and the cariogenic challenge occurred on subsequent five days, twice a day. At the end, the percentage of surface hardness loss (%SHL) and biomass was determined and submitted to ANOVA followed by Tukey's test. Sucrose presented the highest rate of demineralization, however, all sweeteners tested lead to a statistically higher root demineralization compared to the negative control (p <0.05). Sucrose caused greater demineralization in root dentin, however, the sweeteners were also able to induce it under this biofilm model.

RESUMEN: El objetivo del presente estudio fue evaluar el efecto de los edulcorantes comerciales en la desmineralización de la dentina radicular utilizando un modelo de biofilm microcosmo. Se asignaron al azar muestras de dentina bovina con una dureza de la superficie predeterminada de acuerdo con los edulcorantes estudiados: sucralosa, estevia, sacarina, aspartame. La sacarosa se utilizó como control positivo y un grupo no tratado como control negativo. Las muestras se enviaron al desarrollo de biopelículas de un donante de saliva y el desafío cariogénico se produjo en los siguientes cinco días, dos veces al día. Al final, se determinó el porcentaje de pérdida de dureza de la superficie (% PDS) y biomasa y se aplicó un estudio estadístico de ANOVA seguido de la prueba de Tukey. La sacarosa presentó la mayor tasa de desmineralización; sin embargo, todos los endulzantes probados condujeron a una desmineralización de la raíz estadísticamente mayor en comparación con el control negativo (p<0,05). La sacarosa causó una mayor desmineralización en la dentina de raíz, sin embargo, los edulcorantes también fueron capaces de inducirla bajo este modelo de biofilm.

The periodontal pocket: pathogenesis, histopathology and consequences.

The conversion of junctional epithelium to pocket epithelium is regarded as a hallmark in the development of periodontitis. Knowledge of factors contributing to the initiation and progression of pocket formation is important and may result in the development of better preventive measures and improve healing outcomes after therapeutic interventions. The periodontal pocket is a pathologically deepened gingival sulcus. In healthy periodontal conditions, the defense mechanisms are generally sufficient to control the constant microbiological challenge through a normally functioning junctional epithelium and the concentrated powerful mass of inflammatory and immune cells and macromolecules transmigrating through this epithelium. In contrast, destruction of the structural integrity of the junctional epithelium, which includes disruption of cell-to-cell contacts and detachment from the tooth surface, consequently leading to pocket formation, disequilibrates this delicate defense system. Deepening of the pocket apically, and also horizontal expansion of the biofilm on the tooth root, puts this system to a grueling test. There is no more this powerful concentration of defense cells and macromolecules that are discharged at the sulcus bottom and that face a relatively small biofilm surface in the gingival sulcus. In a pocket situation, the defense cells and the macromolecules are directly discharged into the periodontal pocket and the majority of epithelial cells directly face the biofilm. The thinning of the epithelium and its ulceration increase the chance for invasion of microorganisms and their products into the soft connective tissue and this aggravates the situation. Depending on the severity and duration of disease, a vicious circle may develop in the pocket environment, which is difficult or impossible to break without therapeutic intervention.

A Comparison of Er:YAG Laser with Photon-Initiated Photoacoustic Streaming, Nd:YAG Laser, and Conventional Irrigation on the Eradication of Root Dentinal Tubule Infection by Enterococcus faecalis Biofilms: A Scanning Electron Microscopy Study.

This study evaluated the antimicrobial efficacy of Er:YAG laser activation with photon-initiated photoacoustic streaming (PIPS), Nd:YAG laser disinfection, and conventional irrigation on Enterococcus faecalis biofilms using scanning electron microscopy (SEM). Biofilms were grown on 110 root halves and divided into the following: Groups 1 and 2 (saline and 1% NaOCl with apical position of PIPS, resp.), Groups 3 and 4 (saline and 1% NaOCl with coronal position of PIPS, resp.), Groups 5 and 6 (Nd:YAG laser after saline and 1% NaOCl irrigation, resp.) and Groups 7, 8, and 9 (conventional irrigation with 1% NaOCl, 6% NaOCl, and saline, resp.). SEM images of the apical, middle, and coronal levels were examined using a scoring system. Score differences between Groups 1 and 2 were insignificant at all levels in the remaining biofilm. Group 4 had significantly greater bacterial elimination than Group 3 at all levels. Differences in Nd:YAG laser irradiation between Groups 5 and 6 were insignificant. Groups 7 and 8 were insignificantly different, except at the middle level. Saline group had a higher percentage of biofilms than the others. In this study, PIPS activation with NaOCl eliminates more E. faecalis biofilms in all root canals regardless of the position of the fiber tip.

Persistent extra-radicular bacterial biofilm in endodontically treated human teeth: scanning electron microscopy analysis after apical surgery.

Biofilms are the main cause of endodontic failures. Even the best executed endodontic treatment can fail, when the infection is resistant to treatment or when it is located in inaccessible areas, such as the external surface of the root apex. The purpose of this study was to evaluate, by scanning electron microscopy, the presence of bacterial biofilm on endodontically treated teeth considered clinical failures and suitable for apical surgery. Root apices were collected from 20 teeth undergoing apical surgery and one negative control and analyzed under SEM. Digital photomicrographs of the root apices of 21 specimens at different magnifications were taken. Data were analyzed using descriptive statistics. Apical biofilms were observed in 100% of root canal treatments considered endodontic failure. Topographical analysis of the root apices revealed areas of resorption, microcracks, and apical foramina in 90%, 80%, and 50% of cases, respectively. Within the limits of this study, it can be concluded that endodontic failures present bacterial biofilm in areas inaccessible to conventional endodontic treatment, such as the external surfaces of the root apex.

Host-Bacterial Interactions in Post-treatment Apical Periodontitis: A Metaproteome Analysis.

INTRODUCTION: This study evaluated the bacterial and human metaproteome of root apexes and the matched inflammatory lesions from teeth with post-treatment apical periodontitis. METHODS: Root apexes and matched inflammatory lesions from root canal-treated teeth with apical periodontitis were obtained during periradicular surgery. All root canal fillings were rated as adequate on the basis of radiographs and cone-beam computed tomography. The specimens were cryopulverized and subjected to metaproteomic analysis for human and bacterial proteins by using a mass spectrometry platform that is based on nanoflow liquid chromatography coupled with linear ion trap quadrupole Velos Orbitrap. RESULTS: The metaproteome analyses revealed the presence of viable and metabolically active human and bacterial cells in both apexes and lesions. Several bacterial proteins of interest for pathogenicity and therapeutics were identified in both apexes and lesions, including proteins related to antibiotic resistance, proteolytic function, stress response, adhesion, and virulence. Many human proteins related to immune defense mechanisms were also detected in both root apex and lesion specimens, including immunoglobulins, complement system, and proteins linked to T-cell and B-cell activation, neutrophil microbicidal processes, antigen recognition/presentation, bone resorption, and protection against tissue damage. CONCLUSIONS: Occurrence of host defense factors from the innate and adaptive immune responses and bacterial virulence, survival, and resistance proteins in matched root apexes/periradicular inflammatory lesions indicates a complex and dynamic host-pathogen interaction in teeth with post-treatment apical periodontitis.

Sealing ability of MTA, CPM, and MBPc as root-end filling materials: a bacterial leakage study

ABSTRACT Objectives To evaluate the sealing ability of three root-end filling materials (white MTA, CPM, and MBPc) using an Enterococcus faecalis leakage model. Material and Methods Seventy single-root extracted human teeth were instrumented and root-ends were resected to prepare 3 mm depth cavities. Root-end preparations were filled with white MTA, CPM, and MBPc cements. Enterococcus faecalis was coronally introduced and the apical portion was immersed in BHI culture medium with phenol red indicator. The bacterial leakage was monitored every 24 h for 4 weeks. The statistical analysis was performed using the Wilcoxon-Gehan test (p<0.05). Results All cements showed bacterial leakage after 24 hours, except for the negative control group. The MBPc showed significantly less bacterial leakage compared with the MTA group (p<0.05). No significant differences were found between the CPM and the other groups. Conclusions The epoxy resin-based cement MBPc had lower bacterial leakage compared with the calcium silicate-based cements MTA and CPM.

In vivo model for microbial invasion of tooth root dentinal tubules

ABSTRACT Objective Bacterial penetration of dentinal tubules via exposed dentine can lead to root caries and promote infections of the pulp and root canal system. The aim of this work was to develop a new experimental model for studying bacterial invasion of dentinal tubules within the human oral cavity. Material and Methods Sections of human root dentine were mounted into lower oral appliances that were worn by four human subjects for 15 d. Roots were then fixed, sectioned, stained and examined microscopically for evidence of bacterial invasion. Levels of invasion were expressed as Tubule Invasion Factor (TIF). DNA was extracted from root samples, subjected to polymerase chain reaction amplification of 16S rRNA genes, and invading bacteria were identified by comparison of sequences with GenBank database. Results All root dentine samples with patent tubules showed evidence of bacterial cell invasion (TIF value range from 5.7 to 9.0) to depths of 200 mm or more. A spectrum of Gram-positive and Gram-negative cell morphotypes were visualized, and molecular typing identified species of Granulicatella, Streptococcus, Klebsiella, Enterobacter, Acinetobacter, and Pseudomonas as dentinal tubule residents. Conclusion A novel in vivo model is described, which provides for human root dentine to be efficiently infected by oral microorganisms. A range of bacteria were able to initially invade dentinal tubules within exposed dentine. The model will be useful for testing the effectiveness of antiseptics, irrigants, and potential tubule occluding agents in preventing bacterial invasion of dentine.

Complex Apical Intraradicular Infection and Extraradicular Mineralized Biofilms as the Cause of Wet Canals and Treatment Failure: Report of 2 Cases.

This article describes 2 cases that showed persistent intracanal exudation (wet canal) even after several visits of antimicrobial endodontic treatment. Histologic and histobacteriologic investigation was conducted for determination of the cause. The 2 cases involved teeth with apical periodontitis lesions, which presented persistent exudation refractory to treatment after several visits. In case 1, it was not possible to achieve a dry canal, and surgery had to be performed. In case 2, attempts to dry the canal succeeded and the canal was filled, but follow-up examination showed an enlarged apical periodontitis lesion and extraction was performed. Biopsy specimens consisting of the root apex and apical periodontitis lesion for case 1 and the whole root for case 2 were subjected to histologic and histobacteriologic analyses. Both cases showed complex bacterial infection in the apical root, affecting both the intraradicular space and the outer root surface. Case 1 showed bacterial biofilms in ramifications, on untouched walls, and extending to the external root surface to form a thick and partially mineralized structure with high bacterial density. Different bacterial morphotypes were evidenced. Case 2 had a ledge on the apical canal wall created during instrumentation, which was filled with necrotic debris, filling material, and bacteria. The walls of the apical portion of the canal were covered by a bacterial biofilm, which was continuous with a thick extraradicular biofilm covering the cementum and dentin in resorptive defects. The extraradicular biofilm showed areas of mineralization and was dominated by filamentous bacteria. The 2 cases with wet canals and treatment failure were associated with complex persistent infection in the apical part of the root canal system extending to form thick and partially mineralized biofilm structures (calculus) on the outer apical root surface.

Influence of Temperature on the Antibacterial Activity of Sodium Hypochlorite

Abstract The aim of this study was to compare the antimicrobial activity of 5.25% NaOCl, Hypoclean and Chlor-Xtra at 20 °C and 45 °C in bovine root dentin. One-hundred-and-seventy dentin tubes prepared from bovine maxillary incisors were infected for 21 days with Enterococcus faecalis. The specimens were divided into the following groups: 1. 5.25% NaOCl 20 °C; 2. Hypoclean 20 °C; 3. Chlor-Xtra 20 °C; 4. 5.25% % NaOCl 45 °C; 5. Hypoclean 45 °C; 6. Chlor-Xtra 45 °C; 7. positive control; 8. negative control. Dentin chips were collected with round burs into Brain Heart Infusion (BHI) broth. After culturing, the number of colony-forming units (CFU) was counted. Statistical analyses were performed using descriptive statistics (mean, standard deviation, median), Shapiro-Wilk test, ANOVA and Tukey test. Significance level was set at p<0.05. In all experimental groups, CFU was minimum after treatment (day 0) and the obtained results were significantly different from each other at any period (p<0.05). After treatment, the Hypoclean and Chlor-Xtra showed the lowest numbers of CFU at 20 °C and 45 °C, whereas 5.25% NaOCl showed the highest number of CFU at both temperatures. In each group, the number of CFUs increased significantly with time (p<0.05). The antibacterial activity of Hypoclean and Chlor-Xtra at 45 °C were significantly greater than other tested solutions.

Resumo O objetivo deste estudo foi comparar a atividade antimicrobiana do hipoclorito de sódio a 5,25%, Hypoclean e Cloro-Xtra a 20 °C e 45 °C em dentina radicular bovina. Um total de 170 tubos de dentina foram preparados a partir de incisivos superiores bovinos infectados por 21 dias com Enterococcus faecalis. Os espécimes foram divididos nos seguintes grupos: 1. NaOCl - 5,25% a 20 °C; 2. Hypoclean 20 °C; 3. Cloro-Xtra 20 °C; 4. NaOCl - 5,25% a 45 °C; 5. Hypoclean 45 °C; 6. Cloro-Xtra 45 °C; 7. Controle positivo; 8. Controle negativo. Raspas de dentina foram coletadas com brocas esféricas e cultivadas em infusão cérebro coração (brain heart infusion - BHI). Após a cultura, o número de unidades formadoras de colônias (UFC) foi contado. As análises estatísticas foram realizadas utilizando estatística descritiva (média, desvio padrão, mediana), teste de Shapiro-Wilk, ANOVA e teste de Tukey. O nível de significância foi estabelecido p<0,05. Em todos os grupos experimentais, o número de UFC foi mínimo após o tratamento inicial. Os resultados obtidos foram significativamente diferentes nos períodos de tempos experimentais (p<0,05). O Hypoclean e o Cloro-Xtra mostraram o menor número de UFC a 20 °C e a 45 °C, enquanto que o NaOCl - 5,25% apresentou maior número de UFC em ambas as temperaturas. Em cada grupo, o número de CFUs foi significativamente aumentado por período de tempo (p<0,05). As atividades antibacterianas do Hypoclean e Chlor-Xtra a 45 °C foram significativamente maiores do que nas outras soluções testadas.

Collagen-like peptide sequences inhibit bacterial invasion of root dentine.

AIM: To investigate the effects of peptides derived from the sequence of collagen to inhibit penetration of human or bovine dentine by species of streptococci and enterococci. METHODOLOGY: Blocks of human or bovine root dentine were infected for 14 days with bacterial cultures, in the presence or absence of various collagen-like peptide sequences. Invasion of dentinal tubules was determined from microscopic images of histochemically stained dentine thin sections. Extent of invasion was expressed as tubule invasion index (TI), or tubule invasion factor (TIF) which, in addition to the density of invasion, took into account the depth of invasion. Data were analysed by two-way anova. RESULTS: Streptococcus gordonii, Streptococcus mutans and Enterococcus faecalis were associated with heavy invasion (TI >2.5, TIF >4) of human or bovine root dentinal tubules, with E. faecalis being the most penetrative. Incorporation of peptides Gly-Pro-Ala or Gly-Pro-Hyp into the in vitro model system significantly reduced (P < 0.05) dentine invasion by the three species of highly invasive organisms. Inhibition of bacterial invasion by the peptides was dose dependent, and the peptides did not inhibit bacterial growth in culture. CONCLUSION: Specific collagen-like peptide sequences inhibited the invasion of dentine in vitro by a range of oral bacteria. The peptides likely act as competitive inhibitors blocking bacterial collagen receptors and could potentially allow for target-specific control of dentine infections.

Bacterial intensity and localization in primary molars with caries disease.

AIM: The aim was to assess the characteristics and outcomes of infections affecting the structures of carious primary molars. MATERIALS AND METHODS: Forty primary molars were used and classified according to the following clinical situation: With profound caries lesion, with bone loss at the furcation region, with perforation of the pulp chamber floor, and residual roots. The teeth were demineralized, cut, and stained with both haematoxylin-eosin and Brown and Brenn staining techniques. Assessment was performed using optical microscopy. RESULTS: Statistical analysis of the data by means of the Chi-square test suggests that there was a significant relationship (P<0.001) between the intensity and localization of infection and the level of destruction of dental structures. A significant difference was also observed in the intensity and localization of infection between the groups regarding crown, furca, and root (P<0.001). CONCLUSION: More intense and profound the infection, more severe is the dental destruction. The groups of residual roots showed the most severe bacterial infection compared to other groups.

Illosis of maxillary sinus in immunocompromised patient. Case report.

Aspergillosis, which was first discovered in late 19th century, is a relatively rare disease in the sinuses. In recent years, a number of invasive aspergillosis infections of the maxillary sinus in immunocompromised patients, as well as the non-invasive form of the disease, have been reported. They were caused by the materials used in endodontic treatment, like gutta-percha, antrolith and by foreign bodies. This paper reports a case of aspergillosis in the maxillary sinus of an immunocompromised patient. It is associated with a root fragment after a much earlier tooth extraction.

Er:YAG laser treatment in supportive periodontal therapy.

OBJECTIVE: To assess clinical and microbiological outcomes of an Er:YAG laser in comparison with sonic debridement in the treatment of persistent periodontal pockets in a prospective randomized controlled multicentre study design. MATERIAL AND METHODS: A total of 78 patients in supportive periodontal therapy with two residual pockets were included, 58 were available for the whole follow-up period. Root surfaces were instrumented either with a sonic scaler (Sonicflex(®) 2003 L) or with an Er:YAG laser (KEY Laser(®) 3). Clinical attachment levels (CAL), Probing depths (PD), Plaque control record (PCR) and Bleeding on probing (BOP) were assessed at baseline, 13 and 26 weeks after treatment. In addition, microbiological analysis was performed employing a DNA diagnostic test kit (micro-IDent(®) Plus). RESULTS: Probing depths and CAL were significantly reduced in both groups over time (p < 0.05), without significant differences between the groups (p > 0.05). BOP frequency values decreased significantly within both groups (p < 0.05), with no difference between the laser and the sonic treatment (p > 0.05). PCR frequency values did not change during the observation period (p > 0.05). Microbiological analysis failed to expose any significant difference based on treatment group or period. CONCLUSION: Employing both sonic and laser treatment procedures during supportive periodontal care, similar clinical and microbiological outcomes can be expected.

In vitro studies of the ablation mechanism of periodontopathic bacteria and decontamination effect on periodontally diseased root surfaces by erbium:yttrium-aluminum-garnet laser.

The erbium:yttrium-aluminum-garnet (Er:YAG) laser is now increasingly used in periodontal therapy. The purpose of this study was to investigate the effect of Er:YAG laser irradiation on the morphology of periodontopathic bacteria and to compare the bacterial elimination effect of the laser and the ultrasonic scaler on diseased root surfaces in vitro. Colonies of Porphyromonas gingivalis were exposed to a single-pulse Er:YAG laser at 40 mJ and were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Also, 20 pairs of periodontally diseased root surfaces with subgingival calculi of freshly extracted teeth were treated by Er:YAG laser scaling at 40 mJ/pulse (14.2 J/cm(2) per pulse) and 10 Hz with water spray or ultrasonic scaling, or were not treated. The efficiency of each treatment was determined as the area treated per second, and the treated surfaces were examined by SEM. The material scraped from the treated root surfaces was cultured in aerobic and anaerobic conditions, and the numbers of colony forming units (CFUs) were compared. SEM and TEM showed that the Er:YAG laser had easily ablated the bacterial colony, leaving an ablation spot with a crater and the surrounding affected area showing melted branch-like structures. The laser irradiation was as equally effective and efficient as the ultrasonic scaler in performing root surface debridement. The CFUs after laser treatment were significantly fewer than those after ultrasonic scaling in aerobic and anaerobic culture conditions. Er:YAG laser ablates periodontopathic bacteria with thermal vaporization, and its bacterial elimination effect on the diseased root surfaces appears to be superior to that of the ultrasonic scaler.

Biofilms and apical periodontitis: study of prevalence and association with clinical and histopathologic findings.

INTRODUCTION: This study evaluated the prevalence of bacterial biofilms in untreated and treated root canals of teeth evincing apical periodontitis. The associations of biofilms with clinical conditions, radiographic size, and the histopathologic type of apical periodontitis were also investigated. METHODS: The material comprised biopsy specimens from 106 (64 untreated and 42 treated) roots of teeth with apical periodontitis. Specimens were obtained by apical surgery or extraction and were processed for histopathologic and histobacteriologic techniques. RESULTS: Bacteria were found in all but one specimen. Overall, intraradicular biofilm arrangements were observed in the apical segment of 77% of the root canals (untreated canals: 80%; treated canals: 74%). Biofilms were also seen covering the walls of ramifications and isthmuses. Bacterial biofilms were visualized in 62% and 82% of the root canals of teeth with small and large radiographic lesions, respectively. All canals with very large lesions harbored intraradicular biofilms. Biofilms were significantly associated with epithelialized lesions (cysts and epithelialized granulomas or abscesses) (p < 0.001). The overall prevalence of biofilms in cysts, abscesses, and granulomas was 95%, 83%, and 69.5%, respectively. No correlation was found between biofilms and clinical symptoms or sinus tract presence (p > 0.05). Extraradicular biofilms were observed in only 6% of the cases. CONCLUSIONS: The overall findings are consistent with acceptable criteria to include apical periodontitis in the set of biofilm-induced diseases. Biofilm morphologic structure varied from case to case and no unique pattern for endodontic infections was identified. Biofilms are more likely to be present in association with longstanding pathologic processes, including large lesions and cysts.

Comparative evaluation of rotary ProTaper, Profile, and conventional stepback technique on reduction in Enterococcus faecalis colony-forming units and vertical root fracture resistance of root canals.

OBJECTIVE: The purpose of this in vitro study was to evaluate the effect of various root canal instrumentation techniques with different instrument tapers on cleaning efficacy and resultant vertical root fracture (VRF) strength of the roots. STUDY DESIGN: Fifty human mandibular first premolar roots were enlarged to ISO size 20, inoculated with Enterococcus faecalis [ATCC2912] for 72 hours and divided into 5 groups: group I: prepared with .02 taper hand instruments ISO size 40; group II: Profile .04 taper size 40; group III: Profile .06 taper size 40; group IV: ProTaper size F4; and group V (control group) further divided into: Va: with bacterial inoculation and no mechanical instrumentation; and Group Vb: neither bacterial inoculation nor mechanical instrumentation. Cleaning efficacy was evaluated in terms of reduction of colony forming units (CFUs). The VRF strength was evaluated using D11 spreader as wedge in an Instron testing machine. RESULTS: Root canals instrumented with ProTaper and 6% Profile instruments showed maximum reduction in CFUs, with statistically insignificant difference between them. The VRF resistance decreased in all instrumented groups. The difference of VRF between 2% and 4% taper Profile groups was statistically insignificant (P = .195). One-way analysis of variance showed that canals instrumented with ProTaper F4 showed maximum reduction in VRF resistance compared with control uninstrumented group. CONCLUSIONS: Profile 6% taper instruments offer the advantage of maximum debridement without significant reduction in root fracture resistance.

Effect of dentin treatment time with tetraclean on its residual antibacterial activity.

The goal of this study was to evaluate the effect of dentin treatment duration (10 minutes, 24 hours, and seven days) with Tetraclean on its residual antibacterial activity in bovine root dentin. Results showed that the number of colony-forming units in all three experimental groups was zero at the first culture. Furthermore, the 10-minute group and seven-day group demonstrated the highest and the lowest number of colony-forming units, respectively.

In vitro adhesion of Streptococcus sanguinis to dentine root surface after treatment with Er:YAG laser, ultrasonic system, or manual curette.

OBJECTIVE: The purpose of this in vitro study was to evaluate the dentine root surface roughness and the adherence of Streptococcus sanguinis (ATCC 10556) after treatment with an ultrasonic system, Er:YAG laser, or manual curette. BACKGROUND DATA: Bacterial adhesion and formation of dental biofilm after scaling and root planing may be a challenge to the long-term stability of periodontal therapy. MATERIALS AND METHODS: Forty flattened bovine roots were randomly assigned to one of the following groups: ultrasonic system (n = 10); Er:YAG laser (n = 10); manual curette (n = 10); or control untreated roots (n = 10). The mean surface roughness (Ra, microm) of the specimens before and after exposure to each treatment was determined using a surface profilometer. In addition, S. sanguinis was grown on the treated and untreated specimens and the amounts of retained bacteria on the surfaces were measured by culture method. RESULTS: All treatments increased the Ra; however, the roughest surface was produced by the curettes. In addition, the specimens treated with curettes showed the highest S. sanguinis adhesion. There was a significant positive correlation between roughness values and bacterial cells counts. CONCLUSION: S. sanguinis adhesion was the highest on the curette-treated dentine root surfaces, which also presented the greatest surface roughness.