Micro-CT Evaluation of Spontaneous Apexification of an Immature Tooth following Trauma.

This case reports on the micro-computerised tomography (CT) images of a periapical calcified dome following spontaneous apexification as a subsequence of trauma. An immature, maxillary central incisor was found to be non-vital one month following trauma. The tooth had minimal signs of structural damage; however, there was radiographic evidence of spontaneous apexification. The tooth suffered a second traumatic episode two years later and was decoronated to facilitate bone retention during osseous development. The patient presented with swelling and pain 36 months later, and the tooth root was extracted. The root was embedded in resin, and cross-sectional images were obtained using micro-CT. Analysis of the images provided insight into the structure of the calcified dome that formed following the first traumatic injury.

The effect of an additional application of sealer prior to backfilling in the Continuous Wave of Condensation technique.

An additional sealer application was investigated prior to backfilling with the Continuous Wave of Condensation (CWC). 105 Palatal roots were sectioned and prepared to a file size 40, 0.06 taper with Vortex Blue® files. Groups A, B and C had a single sealer application before while groups D, E and F, received a second application of dyed sealer prior to backfilling. Roots were sectioned at 2,3,4,6,7 and 8 mm from the root apex. The percentage of sealer and dentinal tubular penetration depth was calculated at each level. At each ascending level, the sealer percentage decreased for each experimental group while the number of outer third penetration depths increased when all groups were combined. An additional sealer application prior to backfilling had minimal effect on the percentage of sealer or outer third penetration depths and can be considered a clinical preference rather than an imperative step with the CWC technique.

Presentation and subsequent care of dental injuries sustained by New Zealand adults.

BACKGROUND/AIMS: Injuries to permanent teeth are common and can have lasting effects, but knowledge of their consequences is deficient because there is a lack of information from longitudinal follow-up studies of adult populations. The aim of this study was to use routinely collected adult dental trauma data from New Zealand's no-fault, Government-run social insurance scheme-the Accident Compensation Corporation-to investigate the presentation and subsequent care of dental injuries sustained by adults. METHODS: Cross-sectional analysis of all new dental injuries recorded during 2008 was followed by prospective analysis of all treatment claimed in the following five years for all new injuries recorded in June 2008 for adults aged 18+ years. Those injuries were categorised into five clinically meaningful, ordinal groups of dental injuries, ranging from least severe (Minor injury) to most severe (Severe displacement). The prospective post-injury treatment information was summarised as (1) restorations; (2) crowns and veneers; (3) completed root canal treatment (preparation and obturation of root canal[s]); (4) extraction (extraction; surgical removal); and (5) implant placement. RESULTS: Orofacial trauma details were recorded for 32 110 individuals (of all ages) in 2008; males predominated in all age groups, except for those aged 65+ years. Of the 68 890 separate injuries to permanent teeth recorded, 74.9% involved maxillary teeth, with almost 50% involving teeth 21 and 11. Some 66.9% of the dental injuries were classified as Minor; 21.7% involved Fractures or loosening, and 8.2% were Severe fractures. Displacement and Severe displacement injuries comprised 1.8% and 2.5% respectively. During June 2008, dental injuries were recorded for 1325 adults. More than 80% of those dental injuries underwent treatment during the subsequent five years, and more severe initial trauma required more complicated treatment. Minor injuries accounted for 33.5%, fractures/loosening for 50.8%, severe fractures for 1.2%, displacements for 8.8%, and severe displacements for 5.8% of the total cost of treatment provided over that five-year period. CONCLUSIONS: Although most injuries sustained were minor, their subsequent treatment burden is not only high but also greater with more severe initial trauma. The ongoing societal cost of orofacial trauma appears to be high.

Mechanical properties, and in vitro biocompatibility assessment of biomimetic dual layered keratin/ hydroxyapatite scaffolds.

A novel biomimetic dual layered keratin/hydroxyapatite (keratin/HA) scaffold was designed using iterative freeze-drying technique. The prepared scaffolds were studied using several analytical techniques to better understand the biological, structural, and mechanical properties. The developed multilayered, interconnected, porous keratin scaffold with different hydroxyapatite (HA) content in the outer and inner layer, mimics the inherent gradient structure of alveolar bone. SEM studies showed an interconnected porous architecture of the prepared scaffolds with seamless integration between the upper and lower layers. The incorporation of HA improved the mechanical properties keratin/HA scaffolds. The keratin/HA scaffolds exhibited superior mechanical properties in terms of Young's modulus and compressive strength in comparison to pure keratin scaffolds. The biocompatibility studies suggested that both keratin and keratin/HA scaffolds were cyto-compatible, in terms of cell proliferation. Furthermore, it showed that both the tested materials can served as an ideal substrate for the differentiation of Saos-2 cells, leading to mineralization of the extracellular matrix. In summary, ionic liquid based green technique was employed for keratin extraction to fabricate keratin/HA scaffolds and our detailed in vitro investigations suggest the great potential for these composite scaffolds for bone tissue engineering in future.

Investigation of a Novel Injectable Chitosan Oligosaccharide-Bovine Hydroxyapatite Hybrid Dental Biocomposite for the Purposes of Conservative Pulp Therapy.

This study aimed to develop injectable chitosan oligosaccharide (COS) and bovine hydroxyapatite (BHA) hybrid biocomposites, and characterise their physiochemical properties for use as a dental pulp-capping material. The COS powder was prepared from chitosan through hydrolytic reactions and then dissolved in 0.2% acetic acid to create a solution. BHA was obtained from waste bovine bone and milled to form a powder. The BHA powder was incorporated with the COS solution at different proportions to create the COS-BHA hybrid biocomposite. Zirconium oxide (ZrO2) powder was included in the blend as a radiopacifier. The composite was characterised to evaluate its physiochemical properties, radiopacity, setting time, solubility, and pH. Fourier-transform infrared spectroscopic analysis of the COS-BHA biocomposite shows the characteristic peaks of COS and hydroxyapatite. Compositional analysis via ICP-MS and SEM-EDX shows the predominant elements present to be the constituents of COS, BHA, and ZrO2. The hybrid biocomposite demonstrated an average setting time of 1 h and 10 min and a pH value of 10. The biocomposite demonstrated solubility when placed in a physiological solution. Radiographically, the set hybrid biocomposite appears to be more radiopaque than the commercial mineral trioxide aggregate (MTA). The developed COS-BHA hybrid biocomposite demonstrated good potential as a pulp-capping agent exhibiting high pH, with a greater radiopacity and reduced setting time compared to MTA. Solubility of the biocomposite may be addressed in future studies with the incorporation of a cross-linking agent. However, further in vitro and in vivo studies are necessary to evaluate its clinical feasibility.

Enterococcus faecalis V583 cell membrane protein expression to alkaline stress.

Enterococcus faecalis is able to adapt to alkaline conditions and is commonly recovered from teeth in which endodontic treatment has failed. The role that E. faecalis membrane proteins play in survival strategies to extreme alkaline conditions is unclear. We grew E. faecalis V583 in a chemostat at pH 8 and 11 at one-tenth the organism's relative maximum growth rate. Following membrane shaving, isotope-coding protein labels were added at the peptide level to samples and then combined. The relative proportion of membrane proteins were identified using LC-ESI mass spectrometry and MaxQuant analysis. Ratios of membrane proteins were log2 transformed, with proteins deviating by more than 1 SD of the mean considered to be up- or down-regulated. A total of six proteins were up-regulated in pH 11 including: EF0669 (polysaccharide biosynthesis family); EF1927 (glycerol uptake facilitator), and EF0114 (glycosyl hydrolase). A total of five proteins were down-regulated including: EF0108 (C4-dicarboxylate transporter); EF1838 (PTS system IIC component); EF0456 (PTS system IID component); and EF0022 (PTS mannose-specific IID component). In extreme alkaline conditions, the membrane proteins of E. faecalis seem to be involved in a shift of carbohydrate metabolism from the PTS system to glycerol, which supports the formation of a protective capsule protecting the cell.

Alkaline Tolerance and Biofilm Formation of Root Canal Isolates of Enterococcus faecalis: An In Vitro Study.

INTRODUCTION: The aim of this study was to compare the effects of glucose and glycerol (provided as principal fermentable supplements) on alkaline tolerance and biofilm-forming capabilities of root canal-derived strains of Enterococcus faecalis and those from other environments. METHODS: The planktonic growth kinetics and the biofilm-forming capabilities of E. faecalis isolates (identified by 16S ribosomal DNA sequencing) were compared when supplied with glucose and glycerol at pH levels of 8 and 11 in a microtiter plate. The metabolic activity of the biofilms plate that formed at a neutral pH level (supplied with either glucose or glycerol) was measured after subsequent adjustment to a pH level of 11. RESULTS: Ten isolates (7 from root canals and 3 from other sources) were examined. The lag phase and the doubling time increased under elevated alkalinity irrespective of either the fermentable supplement (glucose or glycerol) or the origin of the isolate. Biofilm formation and metabolic activity varied among strains, but neither was related to the source of isolation. In general, biofilm formation was enhanced when grown in glucose compared with glycerol and at a pH of 8 compared with a pH of 11 (irrespective of the fermentable supplement). The provision of glycerol did not increase either the planktonic growth rate or biofilm development compared with glucose but significantly increased the metabolic activity of biofilms, especially at a pH of 11 compared with a pH of 8. CONCLUSIONS: In the nutrient-deprived environment of a necrotic or root-filled root canal, glycerol may be an alternative energy source that can promote increased metabolic activity of E. faecalis under alkaline treatment conditions.

Development and Analysis of a Hydroxyapatite Supplemented Calcium Silicate Cement for Endodontic Treatment.

Aim: To develop an endodontic cement using bovine bone-derived hydroxyapatite (BHA), Portland cement (PC), and a radiopacifier. Methods: BHA was manufactured from waste bovine bone and milled to form a powder. The cements were developed by the addition of BHA (10%/20%/30%/40% wt), 35% wt, zirconium oxide (radiopacifier) to Portland cement (PC). A 10% nanohydroxyapatite (NHA) cement containing PC and a radiopacifier, and a cement containing PC (PC65) and a radiopacifier were also manufactured as controls. The cements were characterised to evaluate their compressive strength, setting time, radiopacity, solubility, and pH. The biocompatibility was assessed using Saos-2 cells where ProRoot MTA acted as the control. Compressive strength, solubility and pH were evaluated over a 4-week curing period. Results: The compressive strength (CS) of all cements increased with the extended curing times, with a significant CS increase in all groups from day 1 to day 28. The BHA 10% exhibited significantly higher CS compared with the other cements at all time points investigated. The BHA 10% and 20% groups exhibited significantly longer setting times than BHA 30%, 40% and PC65. The addition of ZrO2 in concentrations above 20% wt and Ta2O5 at 30% wt resulted in a radiopacity equal to, or exceeding that of, ProRoot MTA. The experimental cements exhibited relatively low cytotoxicity, solubility and an alkaline pH. Conclusions: The addition of 10% and 20% BHA to an experimental PC-based cement containing 35% ZrO2 improved the material's mechanical strength while enabling similar radiopacity and biocompatibility to ProRoot MTA. Although BHA is a cost-effective, biomimetic additive that can improve the properties of calcium silicate endodontic cements, further studies are now warranted to determine its clinical potential.

Traumatic dental injuries among New Zealanders: Findings from a national oral health survey.

BACKGROUND/AIM: Little is known about adult dental trauma experience at the population level. The aim of this study was to estimate the prevalence and associations of dental injuries in New Zealand (NZ) adults. MATERIALS AND METHOD: Information about dental and orofacial trauma in a representative sample of NZ adults (aged 18-94) was collected in a national oral health survey. As well as self-reported information, the maxillary six anterior teeth were examined for signs of dental trauma. Survey weights were used. RESULTS: Of the 40.9% (95% CI: 37.6, 44.2) who reported previous orofacial trauma, 69.1% (95% CI: 64.3, 73.5), or just over one-quarter of the sample, reported that this included a dental injury. More males than females had experienced orofacial trauma (51.3% [95% CI: 45.8, 56.8] and 31.4% [95% CI: 27.9, 35.1], respectively). The most common injury was a "chipped or broken tooth" (66.6%, 95% CI: 60.6, 72.1). Almost three-quarters had sought treatment. Clinical examination revealed an overall trauma prevalence of 23.4% (95% CI: 21.0, 26.0) with more males than females affected. Some 14.9% (95% CI: 12.8, 17.2) had one injured tooth, while 6.5% (95% CI: 5.2, 8.1) had two injured teeth. The maxillary central incisors were the most frequently affected. Most participants with clinical signs of trauma had only one of the six maxillary teeth affected. The most common clinical dental trauma observation was evidence of "treatment" or an "untreated enamel fracture", and these were more common among males and those aged 35-44 years. CONCLUSION: Traumatic dental injuries constitute an important public health issue. More emphasis on preventing them in the NZ adult population is warranted, and public awareness of State-funded cover for dental injuries may need to be bolstered to enable equitable access for injury care. Overall, a greater emphasis on prevention and the importance of initial care for dental injuries could reduce the individual and societal burden.

An Intervention Study: Does a Cognitive Reappraisal Technique Reduce the Perceived Stress in Fourth-Year Dental Students in New Zealand?

BACKGROUND: The fourth-year of the Bachelor of Dental Surgery (BDS) degree is considered the most stressful in the curriculum. Cognitive reappraisal is a self-applied method of stress management where an individual recognises his/her physiological responses to stress as a positive phenomenon helping him/her rise to the challenge, rather than a negative one in response to a threat situation. AIM: To investigate whether teaching fourth-year dental students to apply cognitive reappraisal reduces their perceived levels of stress. METHODS: A survey was emailed to all fourth-year dental students, inviting them to respond to a 20-item questionnaire adapted from the Dental Environmental Stress (DES) Survey. Respondents were randomly assigned to reappraisal intervention/experimental (EXP) and control intervention (CON) groups, and each group was asked to watch an educational video. The EXP group video educated respondents on how to apply cognitive reappraisal in stressful situations, and the CON group video described generic methods of stress management. A follow-up survey was conducted after 3 weeks. RESULTS: The respondent rate was 47.6%. Change scores were calculated by subtracting the follow-up DES scores from baseline DES scores. The average change score for the experimental group was +3.1, indicating a decrease in average perceived stress levels. Conversely, the average change score for the CON group was -1.06, indicating an increase in average perceived stress levels. However, this difference did not reach a statistical significance. CONCLUSION: EXP group has shown to have positive effects on stress management, and its effects on BDS students demonstrate promise.

Direct Restorations, Endodontics, and Bleaching: Materials and Techniques Used by General Dentists of New Zealand.

BACKGROUND: To investigate the selection and use of direct restorative materials, endodontic techniques adopted, and approaches to bleaching by general dentists in New Zealand. METHODS: A questionnaire comprising 19 sections and 125 questions was distributed via mail to 351 general dentists in New Zealand who were selected, at random, from the Dental Council of New Zealand's 2016 register. RESULTS: A total of 204 questionnaires were returned, of which 188 were usable. Direct resin composite was the most commonly used material for occlusoproximal cavity restorations in premolars (93.7%) and permanent molars (85.2%). Resin-modified glass ionomer cements (34%) and resin composite materials (31.4%) were more commonly used in the restoration of deciduous molars. Home-based vital bleaching was provided by a significant number of dentists (86%), while only 18% provided practice-based bleaching. Cold lateral condensation was the most commonly used obturation technique (55.8%), and 83% of respondents reported using rubber dam for treatments. CONCLUSIONS: The findings from this study indicate that dentists in New Zealand are adapting to new materials and technologies to provide high quality care to their patients. Aesthetic treatments such as bleaching have become an integral part of general dental practice.

Indirect Restorations and Fixed Prosthodontics: Materials and Techniques Used by General Dentists of New Zealand.

BACKGROUND: To investigate the selection and use of materials and techniques for core buildup, indirect restorations, and fixed prosthodontics by general dentists in New Zealand. METHODS: A questionnaire comprising 19 sections and 125 questions was distributed via mail to 351 general dentists in New Zealand who were selected from the Dental Council of New Zealand's 2016 register. RESULTS: The majority of the respondents (68.8%) reported using resin composite light-cured materials for the core buildup of vital posterior teeth. A large number of respondents (52%) did not use dentine pins, with the majority of them (25%) being recent graduates (<10 years). Fibre posts were used by 61.6% of the dentists surveyed. The majority of dentists (54.6%) reported using addition-cured silicone impression material for crown and bridge impressions. Glass-ionomer cements (37.5% of participants) and resin-modified glass-ionomer cements (35.8%) were the most common luting cements used. Direct resin composite veneers were the preferred material of choice rather than indirect restoration of anterior teeth (40.4%). CONCLUSIONS: The study showed that New Zealand dentists surveyed are using current state-of-the-art materials and techniques, with their choice of material being greatly influenced by clinical indications and patients aesthetic demands.

Efficacy of laser and ultrasonic-activated irrigation on eradicating a mixed-species biofilm in human mesial roots.

This study investigated the efficacy of Er,Cr:YSGG laser and ultrasonic activated irrigation on eradicating a mixed-species biofilm grown in root canals with complex anatomy. The biofilm was grown over 4-weeks in the root canals of decoronated human mandibular molar teeth. Control roots received no further treatment. The remaining roots were chemomechanically prepared using different irrigating protocols: 4% NaOCl and 15% EDTAC with ultrasonic activated irrigation and laser activated irrigation using power settings of 0.5 W and 0.75 W. Cellular viability was determined using serial plating. One tooth from each group was subjected to qualitative SEM analysis. Quantification by culturing revealed significant differences between control group and all other treatment groups. This study demonstrated that chemomechanical irrigation with laser and ultrasonic activated irrigation significantly reduced the bacterial load from complex root canal systems; however, there were no significant differences found between the experimental groups.

Demographics, Practising Arrangements, and Standards: Survey among New Zealand Dentists.

BACKGROUND: To determine the demographic profile and practising arrangements of general dentists in New Zealand. METHODS: A questionnaire comprising 19 sections with 125 questions was distributed via mail to 351 general dentists in New Zealand who were selected, at random, from the Dental Council of New Zealand's 2016 register. RESULTS: Two hundred and four questionnaires were returned, of which 188 were usable giving a response rate of 53.5%. The majority of the respondents (63.5%) were male and practice principals (56.8%). Fifty-nine percent of the practices were located in city or town centres with a wide geographic distribution. Sole practitioners accounted for 24.1% of respondents, with the mean number of dentists per practice being 3.2. The majority of respondents (71.6%) attended five or more continuing professional development courses in the past year. Ninety-one percent of respondents used a computerized management system, and 95.3% used the Internet. The use of nickel-titanium endodontic files (83.9%) and digital imaging (82.2%) was the most frequently cited clinical innovations. Articaine was the most popular local anaesthetic of choice. CONCLUSIONS: Dentistry is an ever-changing profession, with evidence that NZ dentists continue to develop, learn, and embrace advancements in technologies to supply high-quality evidence-based treatment.

Isolation and identification of Enterococcus faecalis membrane proteins using membrane shaving, 1D SDS/PAGE, and mass spectrometry.

Enterococcus faecalis is a significant nosocomial pathogen, which is able to survive in diverse environments and resist killing with antimicrobial therapies. The expression of cell membrane proteins play an important role in how bacteria respond to environmental stress. As such, the capacity to identify and study membrane protein expression is critical to our understanding of how specific proteins influence bacterial survival. Here, we describe a combined approach to identify membrane proteins of E. faecalis ATCC V583 using membranes fractionated by either 1D SDS/PAGE or membrane shaving, coupled with LC-ESI mass spectrometry. We identified 222 membrane-associated proteins, which represent approximately 24% of the predicted membrane-associated proteome: 170 were isolated using 1D SDS/PAGE and 68 with membrane shaving, with 36 proteins being common to both the techniques. Of the proteins identified by membrane shaving, 97% were membrane-associated with the majority being integral membrane proteins (89%). Most of the proteins identified with known physiology are involved with transportation across the membrane. The combined 1D SDS/PAGE and membrane shaving approach has produced the greatest number of membrane proteins identified from E. faecalis to date. These protocols will aid future researchers investigating changes in the membrane proteome of E. faecalis by improving our understanding of how E. faecalis adapts and responds to its environment.

Evaluation of Hydroxyl Radical Diffusion and Acidified Thiourea as a Scavenger during Intracoronal Bleaching.

INTRODUCTION: The diffusion of hydroxyl radicals in intracoronal bleaching is associated with a risk of invasive cervical resorption. The use of acidified thiourea has been recommended as a scavenger of residual radicals generated during intracoronal bleaching. The aims of this study were to quantify hydroxyl radical diffusion to external root surfaces after intracoronal bleaching with commonly used materials and to evaluate the effect of using acidified thiourea with hydrogen peroxide (H2O2) on hydroxyl radical diffusion. METHODS: Eighty-two human premolars were prepared, stained, root filled, and allocated to experimental and control groups as follows: group 1: sodium perborate (SP) and water (n = 21), group 2: H2O2 (n = 21), group 3: acidified thiourea and H2O2 (n = 21), group 4: neutral thiourea and H2O2 (n = 10), control group 1: negative control (water) (n = 10), and control group 2: positive control (SP and H2O2) (n = 10). Materials were placed into the pulp chamber, sealed, and placed in 5 mmol/L terephthalic acid at 37°C for 48 hours. Hydroxyl radicals were quantified using a fluorescence microplate reader and high-performance liquid chromatography with fluorescence detection. RESULTS: The H2O2 and SP mixture resulted in the greatest hydroxyl radical diffusion and was significantly greater than SP and water (P < .05) and H2O2 (P < .05). The addition of acidified thiourea resulted in higher radical diffusion, whereas the addition of neutral thiourea resulted in lower diffusion than H2O2 alone. CONCLUSIONS: The SP and water mixture resulted in the lowest hydroxyl radical diffusion, and the H2O2 and SP mixture resulted in the greatest. Although the addition of acidified thiourea to H2O2 did not reduce radicals detected, the addition of neutral thiourea had a positive effect.

Standardisation of sheep model for endodontic regeneration/revitalisation research.

OBJECTIVE: Different endodontic regeneration/revitalisation protocols have been suggested for the treatment of immature permanent teeth with pulp necrosis. Many aspects of these protocols require further investigating necessitating a suitable standardised animal model for research purposes. The focus of this study was to examine the anatomy and histology of sheep teeth at different stages of development to find an appropriate dental age for endodontic regeneration/revitalisation research. DESIGN: Sheep teeth at mature and immature dental ages were investigated. Standardized radiography, computed tomography, and histology were used to measure root length, apical-third dentine thickness and apex diameter, and to evaluate tissue development stages. RESULTS: A mature sheep tooth has an apical area which consists of a major foramen, intermediate dilatation and minor foramen. From the time of eruption to maturation no major changes occur in the incisor root lengths, but the apical foramen width decreases and the dentinal wall thickness increases. The two-tooth age exhibited the most similar features to that of an immature permanent human tooth. CONCLUSION: Sheep appears to be an appropriate animal model for endodontic regeneration/revitalization research with similar dimension and characteristics to human anterior teeth. Each dental age has its advantages and disadvantages. The two-tooth age showed the most favourable criteria making this age the most suitable for in vivo regeneration/revitalisation research.

The effect of sodium hypochlorite on Enterococcus faecalis when grown on dentine as a single- and multi-species biofilm.

Enterococcus faecalis is often involved in the aetiology of apical periodontitis after endodontic treatment. This project aimed to establish, on dentine in vitro, a multi-species biofilm containing E. faecalis, and to determine if the organism had an increased resistance to sodium hypochlorite compared with an axenic biofilm. Biofilms were established on dentine discs in flow cells with either E. faecalis alone (axenic) or together with Fusobacterium nucleatum and Streptococcus sanguinis. Following treatment with either 0.9% sodium hypochlorite or saline, the viability of E. faecalis was determined by serial plating and qualitative analysis was performed by scanning electron microscopy and confocal laser scanning microscopy. Viable counts indicated that 0.9% NaOCl is highly effective against E. faecalis grown alone and as part of a multi-species biofilm (P = 0.0005 and P = 0.001, respectively). No significant difference in its survival in the two biofilm types was found (P = 0.8276).

Endodontic bacteria from primary and persistent endodontic lesions in Chinese patients as identified by cloning and 16S ribosomal DNA gene sequencing.

BACKGROUND: Few literatures pertain to the 16S ribosomal DNA (16S rDNA) analysis of bacteria contributing to primary and persistent endodontic lesions, with no information available for the Chinese population. As such, we investigated endodontic bacteria associated with primary and persistent endodontic lesions in adult Chinese patients living in Beijing, China using 16S rDNA gene sequencing techniques. METHODS: Endodontic microbial samples were obtained from fourteen adult Chinese patients and subjected to DNA extraction. Pllymerase chain reaction (PCR) products were cloned and 100 clones from each generated library were randomly selected. Purified plasmid DNA with 16S rDNA gene inserts was sequenced, and the sequences were searched against GenBank databases using the BLASTN algorithm. Only significant identification with the highest-scored BLAST result and 99% minimum similarity was considered for phylotyping. RESULTS: More than 150 taxa were obtained. Primary endodontic infection was mainly associated with Burkholderia cepacia, Actinomyces, Aranicola spp. and Streptococcus sanguinis, whilst Burkholderia cepacia was predominant in the persistent endodontic infections. CONCLUSION: There is a difference in the species profile associated with endodontic infections of Chinese patients living in Beijing in comparison to other geographical or ethnic reports.

Qualitative comparison of sonic or laser energisation of 4% sodium hypochlorite on an Enterococcus faecalis biofilm grown in vitro.

The effectiveness of sonic activation, laser activation and syringe irrigation of 4% sodium hypochlorite in removing an Enterococcus faecalis biofilm was compared. Biofilms were grown in extracted human single rooted teeth using a flow cell apparatus. After 4 weeks' growth, teeth were subjected to each treatment using 4% sodium hypochlorite and radicular dentinal surfaces of the root canals were analysed by scanning electron microscopy. Results showed that sonic activation and syringe irrigation with sodium hypochlorite showed reduced numbers of bacterial cells on the radicular dentine but were not effective in eliminating E. faecalis in the dentinal tubules. Laser activation of sodium hypochlorite resulted in clean dentine walls and undetectable levels of bacteria within dentinal tubules. Qualitatively, sonic or laser activation of 4% NaOCl resulted in greater bacterial reduction compared with syringe irrigation, with laser activation producing the greatest overall reduction.