Pathologic interactions in pulpal and periodontal tissues

Both endodontic and periodontal disease are caused by a mixed anaerobic infection. The pathways for the spread of bacteria between pulpal and periodontal tissues have been discussed with controversy. This article is an attempt to provide a rational approach to the perio-endo/endo-perio question based on a review of the relevant literature. In the light of evidence, clinical concepts for the diagnosis and treatment of lesions involving both periodontal and pulpal tissues are discussed.

Combinations of bacterial species in endodontic infections

AIM

This study was undertaken to investigate combinations of bacteria found in root-canal infections of teeth with periapical bone destruction without clinical signs and symptoms.

METHODOLOGY

Endodontic samples from 58 root canals were cultured anaerobically and microorganisms were counted and identified. Eighty-one combinations of microorganisms were found and tested for a symbiotic relationship using the Fisher's exact test and Odds ratio calculation.

RESULTS

All samples contained microorganisms with a median CFU mL(-1) of 8x10(4) per sample. Strict anaerobic species accounted for 87% of the microflora. The most prevalent bacteria were Prevotella intermedia, Peptostreptococcus micros and Actinomyces odontolyticus, present in 33, 29 and 19%, respectively, of the cultured canals. A significant relationship (P<0.05) and an Odds ratio >2 were found between P. intermedia and P. micros, P. intermedia and P. oralis, A. odontolyticus and P. micros, Bifidobacterium spp. and Veillonella spp.

CONCLUSIONS

These results indicate that endodontic pathogens do not occur at random but are found in specific combinations.

Invasion of vascular cells in vitro by Porphyromonas endodontalis

AIM

The objective of this study was to determine whether laboratory strains and clinical isolates of microorganisms associated with root canal infections can invade primary cultures of cardiovascular cells.

METHODOLOGY

Quantitative levels of bacterial invasion of human coronary artery endothelial cells (HCAEC) and coronary artery smooth muscle cells (CASMC) were measured using a standard antibiotic protection assay. Transmission electron microscopy was used to confirm and visualize internalization within the vascular cells.

RESULTS

Of the laboratory and clinical strains tested, only P. endodontalis ATCC 35406 was invasive in an antibiotic protection assay using HCAEC and CASMC. Invasion of P. endodontalis ATCC 35406 was confirmed by transmission electron microscopy.

DISCUSSION

Certain microorganisms associated with endodontic infections are invasive. If bacterial invasion of the vasculature contributes to the pathogenesis of cardiovascular disease, then microorganisms in the pulp chamber represent potential pathogens.

Direct amplification of rRNA gene sequences for identification of selected oral pathogens in root canal infections

AIM

The purpose of this study was to assess the prevalence of selected oral pathogens in root canal infections and their relationship with symptoms using a highly sensitive technique, the polymerase chain reaction.

METHODOLOGY

Samples were obtained from 91 infected teeth associated with periradicular lesions, including cases of acute periradicular abscesses. DNA was extracted from the samples and analysed for the presence of target microbial species using a PCR-based identification assay.

RESULTS

All samples were positive for the presence of bacteria. Streptococcus anginosus group was detected in 16.7%, Fusobacterium nucleatum in 14.3%, and Bacteroides forsythus in 7.1% of the abscess samples. No pus sample yielded Actinomyces israelii, Actinobacillus actinomycetemcomitans or fungal species. In general, B. forsythus was found in 20% of the cases (16 of 80), S. anginosus in 12% (6 of 50), F. nucleatum in 10% (6 of 60) and A. israelii in 5% (two of 40). A. actinomycetemcomitans was not detected in any case. Fungi were present in only one of 50 cases (2%). There was no correlation between the species and symptoms.

CONCLUSIONS

Direct molecular approaches appear to be a valuable tool for the rapid and reliable diagnosis of infectious diseases, as well as for research purposes. There was no correlation between target microbial species and symptoms.

Bacterial adhesins--their role in tubule invasion and endodontic disease

Bacterial invasion of dentinal tubules is critical to the progression of dental caries and the development of pulp and periapical disease, and may also influence the progression of periodontal disease. However, little is known about the host or bacterial mechanisms involved in tubule invasion. Recent work has demonstrated that bacterial interactions with dentine, and salivary and tissue molecules influence invasion. Salivary molecules such as mucin and immunoglobulin G (IgG) co-aggregate with bacterial cells, which inhibits dentine invasion, while deposition of dentinal tubule fluid molecules e.g. albumin, IgG, or fibrinogen within dentinal tubules also inhibits invasion. Dentine invasion by streptococci has been shown to be associated with a bacterial growth response and adhesion to unmineralized collagen, which are mediated by streptococcal cell-surface antigen I/II polypeptides. These adhesins possess diverse binding properties including binding to salivary glycoprotein, other bacteria, and to collagen. Additionally, some antigen I/II polypeptides facilitate species-specific co-invasion between streptococci and obligate anaerobes that lack the ability to invade by themselves. An understanding of the mechanisms involved in bacterial invasion of dentine should allow development of new control strategies.

A mouse model of inflammatory root resorption induced by pulpal infection

OBJECTIVE

The present study was undertaken to determine the frequency and extent of apical root resorption associated with induced periradicular lesions in mice.

STUDY DESIGN

Bone and root resorption was quantified by using two- and three-dimensional micro-computed tomography (mu-CT) in the lower first molars of mice subjected to pulp exposure and infection.

RESULTS

mu-CT measurements showed significant apical resorption in exposed and infected teeth, resulting in an average distal root shortening of 12.7% (P <.001 vs unexposed). These findings were confirmed with three-dimensional reconstituted images that showed thinning and shortening of the distal root. Tartrate-resistant acid phosphatase clastic cells were associated with resorption lacunae on the cementum of root apices, as well as on bone at the periphery of the periradicular lesions. Brown and Brenn staining showed the presence of bacteria in dentinal tubules adjacent to resorbed cementum.

CONCLUSIONS

Apical root resorption is a prominent and consistent finding associated with periradicular infection in the mouse. This species represents a convenient model for studying the pathogenesis of inflammatory root resorption in vivo.

Patterns of microbial colonization in primary root canal infections

OBJECTIVE

The purpose of this study was to investigate the patterns of microbial infection of root canals in untreated teeth associated with chronic periradicular lesions by use of scanning electron microscopy.

STUDY DESIGN

Fifteen extracted teeth with extensive carious lesions, radiolucent lesions of varying sizes, and attached periradicular lesions after extraction were selected for study. After fixation, lesions were removed and the teeth were split into 2 halves. The teeth were then dehydrated, sputter-coated with gold, and then examined for the patterns of microbial colonization of the root canal system by using a scanning electron microscope.

RESULTS

All examined root canals were infected, and bacterial cells were seen in practically all areas of the root canal system. The pattern of colonization was not uniform between specimens and even within the same specimen. Most of the root canal walls of all specimens were heavily colonized by a root canal microbiota consisting of cocci and/or rods, often forming mixed communities. Spirilla were occasionally observed as single cells or as small clusters between other bacterial forms. Bacteria were often observed penetrating the dentinal tubules. Although a shallow penetration was the most common finding, bacterial cells could be observed reaching approximately 300 microm in some specimens. Yeastlike cells were observed in 1 specimen together with bacteria.

CONCLUSIONS

The root canals of teeth associated with periradicular lesions were heavily infected by bacteria and occasionally by fungi. The pattern of colonization of the root canal microbiota often showed the characteristic of a climax community, which may require special considerations regarding its elimination and prevention of clinical problems. In addition, the observed propagation of the infection to the entire root canal system in teeth associated with periradicular lesions suggests that proper therapeutic measures may be necessary to eliminate the root canal infection completely.

Antimicrobial activity of four root canal sealers against endodontic pathogens

The antibacterial effects of various types of widely used endodontic sealers have not been compared systematically on facultative or obligate anaerobic endodontic pathogens. The aim of this study was to evaluate the antimicrobial properties of four commonly used endodontic sealers: two epoxy-resin-based sealers (AH26, AH plus), one zinc-oxide eugenol-based sealer (N2), and one calcium hydroxide-based sealer (Sealapex). The testing microbes were four facultative anaerobic species (Streptococcus mutans, Streptococcus sanguis, Escherichia coli, and Staphylococcus aureus) and four obligate anaerobic species (Porphyromonas gingivalis, Porphyromonas endodontalis, Fusobacterium nucleatum, and Prevotella intermedia). The freshly mixed sealers were placed into the prepared wells of agar plates inoculated with the test microorganisms. After varying periods of incubation (2 days for facultative anaerobic species and 7 days for obligate anaerobic species), the zones of growth inhibition were observed and measured. All the sealers were distinctly different from each other in their antimicrobial activity. The sealers showed different inhibitory effects depending on the types and bacterial strains. N2 containing formaldehyde and eugenol proved to be the most effective against the microorganisms. The extreme antimicrobial potency of this root canal sealer must be weighted against its pronounced tissue toxic effect.

Strategies to treat infected root canals

Periradicular lesions are diseases either primarily or secondarily caused by microorganisms and therefore they must be prevented or treated accordingly. If the professional is well-versed in both preventing and eliminating the root canal infection, the success rate of endodontic therapy may exceed 90 percent. The present paper discusses theoretical and practical aspects of effective antimicrobial endodontic therapy and delineates strategies to effectively control root canal infections.

Antifungal effects of endodontic medicaments

The eradication of root canal infection is paramount in endodontic treatment. Because fungi are involved in some types of root canal infections, the purpose of this study was to investigate the antifungal effects of several medicaments against the following selected fungal species: Candida albicans, Candida glabrata, Candida guilliermondii, Candida parapsilosis, and Saccharomyces cerevisiae. The agar diffusion test was the method used. Calcium sulphate or zinc oxide in glycerin showed no inhibitory effects towards any selected fungal species. The pastes of calcium sulphate or calcium hydroxide in camphorated paramonochlorophenol (CPMC)/glycerin showed the most pronounced antifungal effects. Calcium hydroxide in glycerin or chlorhexidine, and chlorhexidine in a detergent also showed antifungal activity, which was, however, much lower than the pastes of calcium sulphate or calcium hydroxide in CPMC/glycerin. Strategies using medicaments that have antifungal effects may assist in the successful management of persistent or secondary endodontic infections caused by fungi.

Molecular identification of microorganisms from endodontic infections

A relatively wide range of bacteria have been isolated from root canals using standard culture techniques. However, only 50% of the bacteria in the oral cavity are cultivable (S. S. Socransky et al., Arch. Oral Biol. 8:278-280, 1963); hence, bacterial diversity in endodontic infections is underestimated. This study used a PCR-based 16S rRNA gene assay, followed by cloning and sequencing of 16S rRNA amplicons from a small subset of samples to assess the diversity of bacteria present in infected root canals. A total of 41 clinical samples from 15 de novo and 26 refractory cases of endodontic infections were assessed. Of these samples, 44% were positive by culture and 68% were positive by PCR. Eight samples were selected for further analysis. Of these, the two de novo cases yielded sequences related to those of the genera Enterococcus, Lactobacillus, Propionibacterium, and Streptococcus and two clones were related to previously uncultivated bacteria, while the sinus-associated, de novo case yielded sequences related to those of the genera Lactobacillus, Pantoea, Prevotella, and Selenomonas. The five refractory cases produced clones which were related to the genera Capnocytophaga, Cytophaga, Dialister, Eubacterium, Fusobacterium, Gemella, Mogibacterium, Peptostreptococcus, Prevotella, Propionibacterium, Selenomonas, Solobacterium, Streptococcus, and Veillonella and two clones representing previously uncultivated bacteria. The phylogenetic positions of several clones associated with the Clostridiaceae and Sporomusa subgroups of the Firmicutes grouping are also shown. This study demonstrates that molecular techniques can detect the presence of bacteria in endodontic infections when culture techniques yield a negative result and can be used to identify a wider range of endodontic-infection-related bacteria including the presence of previously unidentified or unculturable bacteria.

Detection of Slackia exigua, Mogibacterium timidum and Eubacterium saphenum from pulpal and periradicular samples using the Polymerase Chain Reaction (PCR) method

AIM

The purpose of this study was to detect Slackia exigua from root canal samples using a sensitive PCR amplification method. Mogibacterium timidum and Eubacterium saphenum were also included because of their culture-difficult properties.

METHODOLOGY

The species-specific PCR primers were prepared according to 16S rDNA sequence analysis data, and confirmed to be effective for PCR amplification as species-specific, respectively. A total of 36 clinical samples were obtained during the first visit of root canal treatment.

RESULTS

The sensitivity of detection was a minimum of 10 organisms for S. exigua and five organisms for M. timidum and E. saphenum, respectively. In seven cases of pulpitis, Sexigua was detected in two cases (29%), and M. timidum in two cases (29%), but E. saphenum was not detected. In 17 cases of root canal treatment, S. exigua was detected in seven cases (41%), M. timidum in 12 cases (71%) and E. saphenum in four cases (24%). In 12 cases of root canal retreatment, S. exigua was detected in three cases (25%), M. timidum in three cases (25%) and E. saphenum in two cases (17%).

CONCLUSIONS

S. exigua, M. timidum and E. saphenum were present in root canal systems, and may be associated with pulpal and periradicular pathosis.

Antimicrobial efficacy of chloroxylenol and chlorhexidine in the treatment of infected root canals

PURPOSE

To investigate the antimicrobial efficacy of a chlorhexidine gluconate (2.0%) and of an ethanolic chloroxylenol solution (10%) as a temporary root canal dressing against selected test microorganisms (Staphylococcus aureus, Streptococcus faecium, Escherichia coli, Candida albicans).

MATERIALS AND METHODS

Extracted single-rooted human teeth were instrumented up to size 40. After removal of the smear layer suspensions of the test microorganisms were inserted into the root canals. After incubation for 48 hrs each suspension of the test organisms was removed and the root canals were filled with one of the two different disinfectants. The teeth were then incubated for 48 hrs. Twelve teeth and three controls were used for each of the four test organisms and each of the two regimens. After incubation, each root canal was instrumented and the removed canal wall dentin was examined microbiologically.

RESULTS

With a contact time of 48 hrs between the two disinfectants and the four bacterial suspensions the medications led to a total killing of microorganisms in 82% of a total of 96 contaminated teeth. In the dentin layer situated 50 microm from the root canal, both medications achieved bacterial killing in a range from 99.9% to 99.99%, depending on the test organism. There were no significant differences (P> 0.1) between the relative antimicrobial activity of the two root canal dressings.

A prognostic model for assessment of the outcome of endodontic treatment: Effect of biologic and diagnostic variables

OBJECTIVE

Many biological variables, endodontic treatment factors, and restorative considerations have been suggested in the literature to affect the outcome of endodontic treatment. However, few attempts have been made recently to study these variables further. The purpose of this study was to identify the biologic and endodontic treatment-associated variables that are most predictive of treatment outcome for conventional endodontic therapy and to determine the magnitude of risk these variables pose on the outcome.

STUDY DESIGN

The population of this historical prospective cohort study comprised a total of 200 teeth with 441 root canals. Diagnostic and treatment information was abstracted from the original patient records. An endodontic follow-up examination was conducted 4 +/- 0.5 years after obturation. Each tooth/root was analyzed according to 3 indices of periradicular status at 2 time points. The main outcome measure was the presence of apical periodontitis. The criteria used for evaluation of the outcome were modified from Strindberg. Data were subjected to univariate and multivariate analysis. Logistic regression models were fit by using various clinical measures to determine which combination of biologic and treatment-associated factors best predicted treatment outcome.

RESULTS

The preoperative pulp diagnosis, the periapical diagnosis, the preoperative periapical radiolucency size, and the sex of the patients were revealed, by means of univariate analysis, to exert a significant influence on endodontic treatment outcome (P <.05). In the logistic regression model, the strongest effect on postoperative healing was the presence and magnitude of preoperative apical periodontitis. In the presence of this variable, no other factor contributed value to the prediction. The correct prediction of this model was 74.7% (P <.05).

CONCLUSION

The major biologic factors influencing the outcome of endodontic treatment appear to be the extent of microbiological insult to the pulp and periapical tissue, as reflected by the periapical diagnosis and the magnitude of periapical pathosis.

Aetiology of root canal treatment failure: why well-treated teeth can fail

LITERATURE REVIEW

Root canal treatment usually fails when the treatment is carried out inadequately. However, there are some cases in which the treatment has followed the highest standards yet still results in failure. In most of the cases, the endodontic failure results from persistent or secondary intraradicular infection. Extraradicular infections may also be implicated in the failure of some cases. In addition, it has been claimed that a few cases can fail because of intrinsic or extrinsic nonmicrobial factors. The purpose of this paper is to discuss the aetiology of the failure of root canal treatment, particularly in cases of well-treated root canals. Indications for the treatment of endodontic failures are also discussed.

Occurrence of Candida albicans in infections of endodontic origin

Microorganisms are recognized as the etiological agent for the majority of pulpal and periradicular disease. Although bacteria have been the most studied, fungi have also been associated with infected root canals. The purpose of this study was to evaluate the contents of infected root canals and aspirates of cellulitis/abscesses of endodontic origin for the presence of Candida albicans using the polymerase chain reaction (PCR). PCR primers specific for the 18S ribosomal RNA gene of C. albicans were used to survey 24 samples taken from infected root canals and 19 aspirates from periradicular infections of endodontic origins. The presence of C. albicans was detected in 5 of 24 (21%) samples taken from root canals, but none was detected in the periradicular aspirates. The results indicate that PCR is an extremely sensitive molecular method that may be used to identify C. albicans directly in samples from infections of endodontic origin.

Comparison of profiles of key periodontal pathogens in periodontium and endodontium

Despite the established anatomical relationship between the periodontal and pulpal tissues, bacterial migration between endodontium and periodontium is still under discussion. The objective of this study was an investigation of profiles of periodontal pathogens in pulpal and periodontal diseases affecting the same tooth by means of 16S rRNA gene directed polymerase chain reaction (PCR). 31 intact teeth with both pulp and marginal infections were investigated. The diagnosis was based on clinical and radiological examination. Samples were taken from the gingival sulcus or periodontal pocket, respectively, with sterile paper points before trepanation of the teeth. After trepanation sterile paper points and Hedstroem files were used for taking samples from the root canal. Specific PCR methods were used to detect the presence of the following pathogens: Actinobacillus actinomycetemcomitans, Bacteroides forsythus, Eikenella corrodens, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia and Treponema denticola. In addition, quantitative competitive PCR was used to determine the total bacterial count of the samples. The investigated pathogens were proven to be present in the endondontium in all disease categories. Particularly in endodontic samples of "chronic apical periodontitis" and "chronic adult periodontitis" profiles of the periodontal pathogens were found. The results confirmed that periodontal pathogens often accompany endodontic infections and supported the idea that the periodontic-endodontic interrelationships should be considered as critical pathways which might contribute to refractory courses of endodontic or periodontal diseases.

Detection of Porphyromonas endodontalis in infected root canals by 16S rRNA gene-directed polymerase chain reaction

Porphyromonas endodontalis has been isolated from the endodontic infections mainly in symptomatic teeth. This study evaluated the occurrence of P. endodontalis in both symptomatic and asymptomatic endodontic infections using 16S rRNA gene-directed polymerase chain reaction. P. endodontalis was detected in 39.5% of the cases (17 of 43 teeth). It was present in 4 of the 6 cases with acute periradicular abscess (66.7%) and in 13 of the 37 other cases (35.1%). The presence of P. endodontalis was associated with an asymptomatic periradicular lesion in 6 cases (25%) and in 10 teeth with tenderness to percussion (52.6%). P. endodontalis was also found in one asymptomatic case without evidence of periradicular pathosis. Our results indicated that, although P. endodontalis is commonly detected in symptomatic cases, it can be present in asymptomatic root canal infections. Further studies should determine if this bacterial species is really an important endodontopathogen.

Coronal microleakage

The microbiological aetiology of periapical periodontitis of endodontic origin is generally accepted. Therefore, bacterial entry into the tooth both initially and secondarily to endodontic therapy is not desirable. Dental restorations and then root fillings in series are intended to prevent recurrent bacterial entry by blocking the access cavity and pulp canal system. This paper reviews whether this intent is realized practically, and what effect an incomplete seal might have on expressed recurrent disease. The aim is to communicate more recent research findings to a wider clinical audience.

Bacteria of asymptomatic periradicular endodontic lesions identified by DNA-DNA hybridization

Possible inclusion of contaminant bacteria during surgery has been problematic in studies of periradicular lesions of endodontic origin. Therefore, in this study, two different surgical techniques were compared. A second problem is that some difficult to cultivate species may not be detected using bacteriological methods. Molecular techniques may resolve this problem. DNA-DNA hybridization technology has the additional advantage that DNA is not amplified. The purpose of this investigation was to determine if bacteria from periradicular endodontic lesions could be identified using DNA-DNA hybridization. A full thickness intrasulcular mucoperiosteal (IS) flap (n = 20) or a submarginal (SM) flap (n = 16) was reflected in patients with asymptomatic apical periodontitis. DNA was extracted and incubated with 40 digoxigenin-labeled whole genomic probes. Bacterial DNA was detected in all 36 lesions. Seven probes were negative for all lesions. In patients with sinus tract communication, in teeth lacking intact full coverage crowns, and in patients with a history of trauma 4-13 probes provided positive signals. Seven probes were positive in lesions obtained by the IS, but not the SM technique. Two probes were in samples obtained with the SM technique, but not the IS. Only Bacteroides forsythus and Actinomyces naeslundii genospecies 2 were present in large numbers using either the IS or the SM technique. The SM flap technique, in combination with DNA-DNA hybridization, appeared to provide excellent data pertaining to periradicular bacteria. These results supported other studies that provide evidence of a bacterial presence and persistence in periradicular lesions.

Intraradicular space: what happens within roots of infected teeth?

The pulpo-dentine complex is normally protected from exogenous substances in the oral cavity by the overlying enamel or cementum. Dental caries, dental trauma, enamel/dentine cracks, and restorative procedures commonly breach the integrity of enamel or cementum and may allow infection of the pulpo-dentine complex to occur, possibly leading to pulp and periapical inflammatory disease. Infection of the intraradicular space is a complex and dynamic process involving interactions between host and microbial factors. An understanding of these factors has led to the development of endodontic techniques that offer predictable success.

Identification and antimicrobial susceptibility of enterococci isolated from the root canal

Enterococci are occurring in opportunistic infections involving the oral cavity. This study has identified enterococcal species in 29 endodontic infections undergoing treatment with Ca (OH)2 dressings. The in vitro antimicrobial susceptibility of 29 isolated enterococcal strains was determined. Enterococcus faecalis was speciated for 26 isolates and Enterococcus faecium for three isolates. In vitro antimicrobial susceptibility testing revealed enterococcal isolates resistant to benzylpenicillin, ampicillin, clindamycin, metronidazole and tetracycline but sensitive to erythromycin and vancomycin. Due to low sensitivity to antimicrobial agents, enterococci may be selected in root canals undergoing standard endodontic treatment and significantly contribute to endodontic treatment failures.

Detection of Treponema denticola in endodontic infections by 16S rRNA gene-directed polymerase chain reaction

A 16S rDNA-based polymerase chain reaction (PCR) method was used to detect the occurrence of Treponema denticola in root canal infections. Samples were collected from 21 single-root teeth having carious lesions, necrotic pulps and radiographic evidences of periradicular bone loss. DNA extracted from the samples was amplified using the PCR assay, which yielded specific fragment of T. denticola 16S rDNA. T. denticola was detected in 11 of 21 cases (52.4%), regardless of the presence or absence of symptoms. Since this spirochete was found in a relatively high percentage of the endodontic infections examined and because it is a pathogenic microorganism involved in periodontal diseases, there are reasons to believe that T. denticola can also participate in the pathogenesis of periradicular lesions of endodontic origin.

[The study of histopathology and bacteriology of coronal pulp tissue in deciduous teeth with deep dentin caries]

OBJECTIVE

To study the status of coronal pulp of deciduous teeth with deep caries and causes of pulpal histopathological changes.

METHODS

45 deciduous molars with occlusal deep caries were selected at random. The patients did not receive any antibiotic for one month. The coronal pulpal histopathology was observed with optical microscopic technique. The bacteria in pulp chamber were cultured by the ways of aerobic and anaerobic culture technique. The dentinal tubular structures and bacteria within the tubules of cavity basal part dentin were studied with scanning electron microscopic technique.

RESULTS

Coronal pulp tissue of 77.8% of deciduous teeth with deep caries showed chronic inflammation to various degrees or chronic pulpitis with acute attack. There were aerobic and anaerobic mixed infection in pulp chambers of 94.9% deciduous teeth with deep caries. It was found that coccus and bacillus invaded into dentinal tubules of cavity basal part. Coccus located inside tubules with intact tubular walls, while tubular walls were destroyed the bacillus was present.

CONCLUSION

There are aerobic and anaerobic mixed infection in pulp chamber of deciduous teeth with deep caries. The coronal pulp tissue shows chronic inflammation to various extent in over 2/3 deciduous teeth with deep caries. Bacillus has stronger destructive power to dental tubules.

Current practice in endodontics

The aim of this series of six articles is to improve the quality of endodontic treatment in general dental practice by considering what is currently being taught in dental schools. This first article considers the rationale behind endodontic treatment, what we are aiming to achieve and why. It looks at the dental and medico-legal issues which dictate the standards of our practice, and sets out the programme for the series.