The human oral cavity contains a number of different habitats, including the teeth, gingival sulcus, tongue, cheeks, hard and soft palates, and tonsils, which are colonized by bacteria. The oral microbiome is comprised of over 600 prevalent taxa at the species level, with distinct subsets predominating at different habitats. The oral microbiome has been extensively characterized by cultivation and culture-independent molecular methods such as 16S rRNA cloning. Unfortunately, the vast majority of unnamed oral taxa are referenced by clone numbers or 16S rRNA GenBank accession numbers, often without taxonomic anchors. The first aim of this research was to collect 16S rRNA gene sequences into a curated phylogeny-based database, the Human Oral Microbiome Database (HOMD), and make it web accessible (www.homd.org). The HOMD includes 619 taxa in 13 phyla, as follows: Actinobacteria, Bacteroidetes, Chlamydiae, Chloroflexi, Euryarchaeota, Firmicutes, Fusobacteria, Proteobacteria, Spirochaetes, SR1, Synergistetes, Tenericutes, and TM7. The second aim was to analyze 36,043 16S rRNA gene clones isolated from studies of the oral microbiota to determine the relative abundance of taxa and identify novel candidate taxa. The analysis identified 1,179 taxa, of which 24% were named, 8% were cultivated but unnamed, and 68% were uncultivated phylotypes. Upon validation, 434 novel, nonsingleton taxa will be added to the HOMD. The number of taxa needed to account for 90%, 95%, or 99% of the clones examined is 259, 413, and 875, respectively. The HOMD is the first curated description of a human-associated microbiome and provides tools for use in understanding the role of the microbiome in health and disease.

The Human Oral Microbiome

Physical and chemical properties of a new root-end filling material.

A report of two cases

http://www.biofilling.com/article/7_2Mineral.pdf

Mineral Trioxide Aggregate: A Comprehensive Literature Review—Part III: Clinical Applications, Drawbacks, and Mechanism of Action

Sealing ability of a mineral trioxide aggregate when used as a root end filling material

Cultural studies have indicated that a subset of the oral microflora is responsible for endodontic infections. Approximately 50% of oral bacteria are unculturable, so it is likely that currently unknown bacteria are present in such infections. In this study, cultural and molecular analyses were performed on the microflora in aspirate samples collected from 5 infected root canals. 16S rDNA sequences from 261 isolates and 624 clones were identified by comparison with database sequences. Sixty-five taxa were identified, of which 26 were found by the molecular method alone. A mean of 20.2 taxa was found in each sample. A new species of Dialister was the only organism present in all 5 samples. Twenty-seven novel taxa were detected, 18 of which belonged to the phylum Firmicutes and 8 to Bacteroidetes. Culture-independent, molecular analysis has revealed a more diverse microflora associated with endodontic infections than that revealed by cultural methods alone.

Molecular and Cultural Analysis of the Microflora Associated with Endodontic Infections

Aim To assess the success rate of the root-end filling material, Mineral Trioxide Aggregate (MTA).

Methodology  Referred adult patients were recruited using strict entry criteria and randomly allocated to receive MTA or IRM. A standardized surgical technique was employed: the root end was resected perpendicularly and a root-end cavity was prepared ultrasonically and filled. A radiograph taken immediately after surgery was compared with those taken at 12 and 24 months. Customised film holders and the paralleling technique were used; radiographs were assessed by two trained observers using agreed criteria. The results from 122 patients (58 in IRM group, 64 in MTA group) after 12 months and 108 patients (47 in IRM group, 61 in MTA group) for the 24-month review period were analysed using the χ2 test.

Results  The highest number of teeth with complete healing at both times was observed when MTA was used. When the numbers of teeth with complete and incomplete (scar) healing, and those with uncertain and unsatisfactory healing were combined, the success rate for MTA was higher (84% after 12 months, 92% after 24 months) compared with IRM (76% after 12 months, 87% after 24 months). However, statistical analysis showed no significant difference in success between materials (P > 0.05) at both 12 and 24 months.

Conclusions  In this study, the use of MTA as a root-end filling material resulted in a high success rate that was not significantly better than that obtained using IRM.

A prospective clinical study of Mineral Trioxide Aggregate and IRM when used as root-end filling materials in endodontic surgery.

The role of intracanal medication as a root canal dressing is re-examined. In pulpectomy and some root canal treatments, where the root canal contains vital pulp tissue, it is doubtful whether a routine intracanal medicament is needed. In infected root canals, intracanal medication has been advocated for many purposes. An intracanal medicament is used to: (i) eliminate any remaining bacteria after canal instrumentation; (ii) reduce inflammation of periapical tissues and pulp remnants; (iii) render canal contents inert and neutralize tissue debris; (iv) act as a barrier against leakage from the temporary filling; (v) help to dry persistently wet canals. However, most of the indications for intracanal medicaments are questionable. Intracanal medicaments should only be used for root canal disinfection as part of controlled asepsis in infected root canals, and their role is secondary to cleaning and shaping of the root canal. Thorough canal debridement and adequate canal preparation are more pertinent, and their importance is emphasized. Bacteriological sampling may be necessary if a tooth does not respond to treatment, to help in the choice of intracanal medicament.

The role of intracanal medication in root canal treatment.

The adaptation and sealing ability of a light-cured glass ionomer cement when used as a retrograde root filling was assessed using a confocal optical microscope with and without a fluorescent dye. This material was compared with a conventional glass ionomer cement and amalgam. The root canals of 60 extracted human single-rooted teeth were prepared and filled with gutta-percha and sealer. All the teeth were apicected, retrograde cavities were prepared, and then divided into three groups of 20 teeth each and filled with the test materials. The light-cured glass ionomer cement was well adapted to the retrograde cavity and apicected root surface. Within the retrograde cavity the cement was often well adapted to one wall, but gaps were found on the opposite cavity wall. This was probably caused by the polymerization contraction of the material. In contrast, the amalgam retrograde root fillings were poorly adapted to the cavities, with gaps between the cavity walls and amalgam. This group exhibited the poorest sealing ability as measured by the extent of dye penetration. The conventional glass ionomer cement was often found smeared over the root face, and there were unfilled voids at the base of some retrograde cavities. The results of the dye leakage study were analysed statistically. The sealing ability of the light-cured glass ionomer cement was significantly better than that of amalgam (P less than 0.001). The dye penetration around the light-cured glass ionomer cement and the conventional glass ionomer cement was not significantly different (P greater than 0.05). However, the sealing ability of the conventional glass ionomer cement was significantly better than that of amalgam (P less than 0.05).

The adaptation and sealing ability of light-cured glass ionomer retrograde root fillings.

FULL CONTENTS: INTRODUCTION, HISTORY AND SCOPE: Introduction Modern endodontics Scope of endodontics Role of microorganisms Tissue response to root canal infection Quality assurance Recent developments References GENERAL AND SYSTEMIC ASPECTS OF ENDODONTICS: Introduction Differential diagnosis of dental pain Maxillary sinus Systemic disease and endodontics Endodontics and infective endocarditis Endodontics in patients with prosthetic hip joints Use of antibiotics in endodontics Control of pain and anxiety Analgesics Dental Practitioners' Formulary References PULP SPACE ANATOMY AND ACCESS CAVITIES: Introduction Nomenclature Accessory and lateral canals Location of apical foramina Pulp space anatomy and race Pulp space anatomy and access cavities Pulp space anatomy of primary teeth Apical enclosure References THE DENTAL PULP: Introduction Pulpal response to irritants Diagnosis of pulpal damage Pulpal irritants Management of deep caries Pulp exposure Traumatic injuries Cracked cusps Pulpal response to periodontal disease and treatment Pulpal response to intra-alveolar surgery References BASIC INSTRUMENTATION IN ENDODONTICS: Introduction Instruments for access cavity preparation Instruments for root canal preparation Instruments for filling root canals Equipment for storing instruments Sterilization of endodontic instruments Equipment for improving visibility References PREPARATION OF THE ROOT CANAL SYSTEM: Introduction Method and rationale for conventional root canal treatment Preparation of the canal Influence of root canal morphology on endodontic preparation Method of instrumentation Root canal preparation Techniques involving initial coronal preparation Techniques involving initial apical preparation Mechanized techniques of root canal preparation Other methods of preparation with future clinical potential Root canal retreatment Key points of root canal preparation References INTRACANAL MEDICATION: Introduction History Rationale and overview of a

Bun San Chong

Papers

Molecular and Cultural Analysis of the Microflora Associated with Endodontic Infections

A prospective clinical study of Mineral Trioxide Aggregate and IRM when used as root-end filling materials in endodontic surgery.

The role of intracanal medication in root canal treatment.

The adaptation and sealing ability of light-cured glass ionomer retrograde root fillings.

Harty's Endodontics In Clinical Practice