Root canal treatment and general health: a review of the literature

Impact of systemic health on treatment outcomes in endodontics

BACKGROUND

The healing of periapical lesions after root canal treatment (RCT) is not the result of the curative action of the treatment. The process of healing begins with inflammation, and is resolved by the clearance of the immunogen that induces the immune response. Then, the periapical tissue itself carries out the healing of the periapical lesion, by repair or by a combination of repair and regeneration, depending on the host's reparative response working properly. The ultimate objective of RCT is to achieve wound healing by removing the source of bacterial antigens and toxins, allowing chronic inflammatory tissue to become reparative tissue. Some systemic conditions increase the susceptibility of the host to infection or impair the tissue reparative response, maintaining the inflammatory process and periapical bone resorption after RCT. This can cause the failure of RCT and even the need for extraction of the affected tooth.

OBJECTIVE

To analyse the scientific literature on the possible influence of systemic conditions on the treatment outcomes in endodontics, as well as to discuss the biological mechanisms that may be involved.

METHODS

The search was carried out in PubMed, SCOPUS and EMBASE. The inclusion criteria established were original scientific articles reporting data about some systemic condition in relation to treatment outcomes in endodontics, including clinical studies and studies carried out in animal models.

RESULTS

Systemic factors (age, nutrition, stress, hormones, smoking habits), and systemic diseases, such as diabetes, cardiovascular diseases, osteoporosis, HIV infection, inflammatory bowel disease, and others, can influence or interfere in the repair of periapical tissues after RCT.

DISCUSSION

Some of these systemic diseases can alter bone turnover and fibroblast function, preventing or delaying periapical wound healing. Others can alter the microvasculature, reducing nutrients and oxygen supply to periapical tissues. As a result, these systemic conditions can decrease the success rate of RCT and provoke incomplete wound healing (typically granulomatous tissue formation) in the periapical region.

CONCLUSIONS

The results of this narrative review show worse success rate of RCT, with higher percentage of postoperative radiolucent periapical lesions and higher proportion of non-retained teeth (RFT), associated with several systemic conditions, such as smoking habits and diabetes.

Association between Endodontic Infection, Its Treatment and Systemic Health: A Narrative Review

The ‘Focal Infection Era in Dentistry’ in the late 19th and early 20th century resulted in widespread implementation of tooth extraction and limited the progress of endodontics. The theory proposed that bacteria and toxins entrapped in dentinal tubules could disseminate systemically to remote body parts, resulting in many types of degenerative systemic diseases. This theory was eventually refuted due to anecdotal evidence. However, lately there has been increased interest in investigating whether endodontic disease could have an impact on general health. There are reviews that have previously been carried out on this subject, but as new data have emerged since then, this review aims to appraise the available literature investigating the dynamic associations between apical periodontitis, endodontic treatment, and systemic health. The available evidence regarding focal infection theory, bacteraemia and inflammatory markers was appraised. The review also collated the available research arguing the associations of apical periodontitis with cardiovascular diseases, diabetes mellitus, adverse pregnancy outcome and autoimmune disorders, along with the effect of statins and immunomodulators on apical periodontitis prevalence and endodontic treatment prognosis. There is emerging evidence that bacteraemia and low-grade systemic inflammation associated with apical periodontitis may negatively impact systemic health, e.g., development of cardiovascular diseases, adverse pregnancy outcomes, and diabetic metabolic dyscontrol. However, there is limited information supporting the effect of diabetes mellitus or autoimmune disorders on the prevalence and prognosis post endodontic treatment. Furthermore, convincing evidence supports that successful root canal treatment has a beneficial impact on systemic health by reducing the inflammatory burden, thereby dismissing the misconceptions of focal infection theory. Although compelling evidence regarding the association between apical periodontitis and systemic health is present, further high-quality research is required to support and establish the benefits of endodontic treatment on systemic health.

The association of dental pulp stones to cardiovascular and renal diseases: A systematic review and meta-analysis

BACKGROUND

Pulp stone (PS) is a dystrophic calcification in the tooth's pulp chamber and was suggested in the literature to be associated with other calcifications in the body. This study aimed to investigate the association of PS to cardiovascular diseases (CVD) and renal stones (RS).

METHODS

Three databases were searched until June 2021 in addition to manual searching of Google Scholar and grey literature. Original studies were only included and critically appraised using an adapted version of the Newcastle-Ottawa scale. The odds ratio (OR) effect measure was calculated using the Mantel-Haenszel statistical test (95% confidence interval [CI]) to investigate the association of PS with CVD and or RS (p-value ˂ 0.05).

RESULTS

The database search identified 4933 studies, and 19 studies were finally included. The risk of bias was low in thirteen studies, moderate in four studies, and high in two studies. The meta-analysis of the moderate-and-low risk of bias studies revealed a significant association between PS and CVD (OR 3.35, 95% CI 1.91-5.89, P < 0.001, I² = 65%), but no association was found between PS and RS. The results also revealed an association between PS and CVD in patients older than 40 (OR 8.78, 95% CI 3.64-21.17, P < 0.001, I² = 0%).

CONCLUSIONS

The current study results showed an association between PS and CVD, but no association was found between PS and RS. PS in patients younger than 40 years, compared to older patients (> 40 years), was associated with CVD.

Survey-Based Research of Knowledge and Perception of Endodontic Treatment on an Indian Subpopulation

Objective To assess the patients' knowledge and perceptions regarding endodontic treatment.

Materials and Methods A questionnaire-based survey was conducted in a group of 400 patients, consisting of questions based on sociodemographic details as well as their knowledge about endodontic treatment. The collected data was tabulated and analyzed using methods of descriptive analysis.

Results The majority of the respondents stated their level of knowledge regarding endodontic treatment as average.

Conclusion Within the limitations of the study, an improvement in the knowledge regarding endodontic treatment among patients was observed.

Clinical Significance Population-based surveys are useful for evaluating the community and patients' mentality toward endodontic treatment. Proper information regarding the treatment modalities can be explained to the patient based on their lack of information, which is of utmost importance to develop a positive approach to root canal treatment.

Evolution of endodontic medicine: a critical narrative review of the interrelationship between endodontics and systemic pathological conditions

Endodontics has gained emphasis in the scientific community in recent years due to the increase in clinical and in animal models studies focused on endodontic medicine, which aims to evaluate the interrelationship between systemic and periapical tissues pathological conditions. These studies have shown that systemic changes can boost the pathogenesis of endodontic infection, favoring its development and progression. A contrary relationship is reported in numerous studies that affirm the potential of endodontic infection to trigger systemic damage and may lead to the worsening of pre-existing pathologies. Recently, the potential of filling materials to develop systemic changes such as neurological alterations had been evaluated, also showing that systemic diseases can negatively influence tissue responses to filling materials after endodontic treatment. Despite advances in endodontic medicine studies, there are still gaps in knowledge on the mechanisms of interactions between apical periodontitis (AP) and systemic diseases and much research to be done. In this sense, this critical narrative literature review aimed to show the evolution of studies in endodontic medicine to help the endodontist to know the role of systemic diseases in the pathogenesis of AP and the possible interference in the repair of periapical tissues after endodontic treatment, as well as to evidence the systemic complications that can be triggered or aggravated in the presence of endodontic infection.

The association between apical periodontitis and adverse pregnancy outcomes: a systematic review

BACKGROUND

The association between adverse pregnancy outcomes (APOs) and maternal apical periodontitis remains unclear as it has not been examined rigorously or reviewed systematically.

OBJECTIVE

To systematically review and critically evaluate the available evidence on the association of maternal apical periodontitis with several APOs.

METHODS

A literature search was conducted using the following electronic databases: Clarivate Analytics' Web of Science, Scopus, PubMed, and Cochrane Central Register of Controlled Trials (CENTRAL), from inception to 25 February 2021, with no language restrictions. Observational studies including longitudinal clinical trials, cohort, case-control and cross-sectional studies of prospective and retrospective design were included. Articles with duplicate or overlapping results, abstract-only papers, case reports, case series, animal studies and reviews were excluded. Two independent reviewers were involved in study selection, data extraction and appraising the included studies; disagreements were resolved by a third reviewer. The Newcastle-Ottawa Scale (NOS) and the adapted form of the NOS were used to assess the quality for case-control and cross-sectional studies, respectively.

RESULTS

Two case-control and one cross-sectional study were included in the current review. The included studies were published between 2015 and 2017, with a total of 1187 participating individuals with an approximate age range of 15 to 40 years. As the included studies reported different outcomes, the heterogeneity of data prevented a meta-analysis being undertaken. The overall quality of the evidence was 'Fair' for two out of three included studies, while one study was categorized as 'Good'.

DISCUSSION

Two out of three included primary studies had a substantial number of methodological inconsistencies and flaws, and therefore caution should be exercised in interpreting the results of this systematic review because several important covariates were not considered in the original investigations.

CONCLUSION

Based on a limited volume and 'Fair' and 'Good' quality of evidence, a positive association between maternal apical periodontitis and APOs was observed. However, more 'Good' quality clinical studies are needed to confirm the results of the current review.

FUNDING

None REGISTRATION: PROSPERO database (CRD42-2191987).

The Genetic and Epigenetic Mechanisms Involved in Irreversible Pulp Neural Inflammation

Aim

To identify the critical genetic and epigenetic biomarkers by constructing the long noncoding RNA- (lncRNA-) related competing endogenous RNA (ceRNA) network involved in irreversible pulp neural inflammation (pulpitis).

Materials and Methods

The public datasets regarding irreversible pulpitis were downloaded from the gene expression omnibus (GEO) database. The differential expression analysis was performed to identify the differentially expressed genes (DEGs) and DElncRNAs. Functional enrichment analysis was performed to explore the biological processes and signaling pathways enriched by DEGs. By performing a weighted gene coexpression network analysis (WGCNA), the significant gene modules in each dataset were identified. Most importantly, DElncRNA-DEmRNA regulatory network and DElncRNA-associated ceRNA network were constructed. A transcription factor- (TF-) DEmRNA network was built to identify the critical TFs involved in pulpitis.

Result

Two datasets (GSE92681 and GSE77459) were selected for analysis. DEGs involved in pulpitis were significantly enriched in seven signaling pathways (i.e., NOD-like receptor (NLR), Toll-like receptor (TLR), NF-kappa B, tumor necrosis factor (TNF), cell adhesion molecules (CAMs), chemokine, and cytokine-cytokine receptor interaction pathways). The ceRNA regulatory relationships were established consisting of three genes (i.e., LCP1, EZH2, and NR4A1), five miRNAs (i.e., miR-340-5p, miR-4731-5p, miR-27a-3p, miR-34a-5p, and miR-766-5p), and three lncRNAs (i.e., XIST, MIR155HG, and LINC00630). Six transcription factors (i.e., GATA2, ETS1, FOXP3, STAT1, FOS, and JUN) were identified to play pivotal roles in pulpitis.

Conclusion

This paper demonstrates the genetic and epigenetic mechanisms of irreversible pulpitis by revealing the ceRNA network. The biomarkers identified could provide research direction for the application of genetically modified stem cells in endodontic regeneration.

Bacteria Residing at Root Canals Can Induce Cell Proliferation and Alter the Mechanical Properties of Gingival and Cancer Cells

Understanding the importance of oral microbiota in human health and disease also leads to an expansion of the knowledge on functional, metabolic, and molecular alterations directly contributing to oral and systemic pathologies. To date, a compelling number of studies have documented the crucial role of some oral cavity-occurring microbes in the initiation and progression of cancers. Although this effect was noted primarily for Fusobacterium spp., the potential impact of other oral microbes is also worthy of investigation. In this study, we aimed to assess the effect of Enterococcus faecalis, Actinomyces odontolyticus, and Propionibacterium acnes on the proliferation capability and mechanical features of gingival cells and cell lines derived from lung, breast, and ovarian cancers. For this purpose, we incubated selected cell lines with heat-inactivated bacteria and supernatants collected from biofilms, cultured in both anaerobic and aerobic conditions, in the presence of surgically removed teeth and human saliva. The effect of oral bacteria on cell population growth is variable, with the highest growth-promoting abilities observed for E. faecalis in relation to human primary gingival fibroblasts (HGF) and lung cancer A549 cells, and P. acnes in relation to breast cancer MCF-7 and ovarian cancer SKOV-3 cells. Notably, this effect seems to depend on a delicate balance between the pro-stimulatory and toxic effects of bacterial-derived products. Regardless of the diverse effect of bacterial products on cellular proliferation capability, we observed significant alterations in stiffness of gingival and lung cancer cells stimulated with E. faecalis bacteria and corresponding biofilm supernatants, suggesting a novel molecular mechanism involved in the pathogenesis of diseases in oral cavities and tooth tissues. Accordingly, it is proposed that analysis of cancerogenic features of oral cavity bacteria should be multivariable and should include investigation of potential alterations in cell mechanical properties. These findings corroborate the important role of oral hygiene and root canal treatment to assure the healthy stage of oral microbiota.

Periapical Status and Quality of Root Canal Fillings in a Moroccan Subpopulation

AIM

The aim of the study was to assess the prevalence of apical periodontitis (AP) and quality of root canal fillings in an adult Moroccan subpopulation.

METHODS

In the study 508 patients were included, attending the Conservative Dentistry Clinic at the Faculty of Dentistry of Casablanca. 508 panoramic and 709 periapical radiographs were observed. The periapical status of all teeth (with the exception of third molars) was examined according to Ørstavik's periapical index. The statistical analysis was performed with the software Epi Info Version 6.04dfr, April 2001.

RESULTS

A total of 12719 teeth were examined. 45.3% of patients had apical periodontitis. 4.2% of teeth were treated endodontically and 70.4% of these treatments were inadequate. 91,5% with inadequate endodontic treatment presented apical periodontitis, while only 8,2% with adequate endodontic treatment had apical periodontitis. The lower molars and the upper premolars were the most affected teeth. The presence of apical periodontitis was correlated significantly with insufficient root canal fillings (p < 0.05).

CONCLUSIONS

The present study found a high prevalence of apical periodontitis in this Moroccan population. Inadequate root canal fillings were associated with an increased prevalence of apical periodontitis.

From focal sepsis to periodontal medicine: a century of exploring the role of the oral microbiome in systemic disease

The oral microbiome is established within a few minutes after birth and consists of stable multi-species communities that engage in a dynamic equilibrium with the host immune system. Dental caries, endodontic infections and periodontal diseases are bacterially driven diseases that are caused by dysbiotic microbiomes. Over a century ago, the focal infection theory implicated these infections in the aetiology of several systemic diseases, ranging from arthritis to neurodegenerative diseases. However, a lack of concrete evidence, combined with the urgency with which clinicians embraced this approach without regard for appropriate case selection, led to its demise within 30 years. In the last decade of the 20th century, the concept of periodontal medicine was introduced to explain the correlations that were being observed between periodontitis and cardiovascular disease, rheumatoid arthritis, Alzheimer's disease, pulmonary disease, pre-term delivery of low birth weight infants and metabolic disease. It was proposed that periodontal pathobionts played a causal role in the initiating or exacerbating certain diseases either by direct invasion or by stimulating a florid immune-inflammatory response that extended into the systemic circulation. This review will examine the strength of current evidence in establishing a causal link between oral pathobionts and systemic disease.

Effects of Cyclosporin-A-induced Immunosuppression on Periapical Lesions in Rats

Cyclosporin A (CsA) might induce immune response alterations in periapical lesions and modify bone remodeling. This study determined the changes that occur in the periapical lesions of rats during CsA administration and after CsA withdrawal. After the induction of periapical lesions, the animals were treated with CsA (0–20 mg/kg/day) for 4 wks. Lesion volumes were measured by computed tomography. Histological observations and immunohistochemical evaluations were performed with anti-CD3 and anti-CD25 antibodies. CsA administration reduced lesion volumes, and the lesions significantly expanded after CsA withdrawal. CsA inhibited the proliferation and activation of T-cells at lesion sites. The effects of CsA on T-cells were dose-dependent up to 10 mg/kg/day, after which no significant difference was evident. These results suggest that CsA inhibits periapical destruction by interfering with T-cell function in periapical lesions.

Therapeutic Potential of Gramicidin S in the Treatment of Root Canal Infections

An intrinsic clindamycin-resistant Enterococcus faecalis, the most common single species present in teeth after failed root canal therapy, often possesses acquired tetracycline resistance. In these cases, root canal infections are commonly treated with Ledermix(®) paste, which contains demeclocycline, or the new alternative endodontic paste Odontopaste, which contains clindamycin; however, these treatments are often ineffective. We studied the killing activity of the cyclic antimicrobial peptide gramicidin S (GS) against planktonic and biofilm cells of tetracycline-resistant clinical isolates of E. faecalis. The high therapeutic potential of GS for the topical treatment of problematic teeth is based on the rapid bactericidal effect toward the biofilm-forming, tetracycline-resistant E. faecalis. GS reduces the cell number of planktonic cells within 20-40 min at a concentration of 40-80 μg/mL. It kills the cells of pre-grown biofilms at concentrations of 100-200 μg/mL, such that no re-growth is possible. The translocation of the peptide into the cell interior and its complexation with intracellular nucleotides, including the alarmon ppGpp, can explain its anti-biofilm effect. The successful treatment of persistently infected root canals of two volunteers confirms the high effectiveness of GS. The broad GS activity towards resistant, biofilm-forming E. faecalis suggests its applications for approval in root canal medication.

Focal infection theory: past and present

The authors present a historical review of and current data on the role of the focal infection in the human body as well as possible development of systemic diseases against its background.

Secondary Treatment for Asymptomatic Root Canal Treated Teeth: A Cost-effectiveness Analysis

INTRODUCTION

When faced with a clinically asymptomatic root canal treated tooth with certain radiographic findings (e.g., underextended or overextended root fillings or persistent periapical lesions), clinicians need to decide between endodontically retreating the tooth before restoration or not retreating it now but possibly later on. The present study compared the cost-effectiveness of both strategies.

METHODS

A Markov model was constructed following a root canal treated, clinically asymptomatic molar with one of the described radiographic findings in a 50-year-old patient during his lifetime. Hazard functions were derived from systematically and non-systematically assessed literature, and costs were estimated for German health care. Monte Carlo microsimulations were performed for teeth with composite restorations, crowns, or post-core crowns, and costs per year of tooth retention were calculated.

RESULTS

Regardless of the radiographic findings, not performing immediate retreatment was found to be significantly less costly (589-954 Euro) and more effective (retention time, 25-29 years) than immediately performing secondary root canal treatment (1163-1359 Euro, 25-27 years). Both strategies had similar effectiveness only for teeth that received post-core crowns, whereas immediate retreatment remained more expensive. The uncertainty around the obtained strategy ranking was low.

CONCLUSIONS

The high costs for secondary root canal treatment do not seem to be outweighed by the increased risks associated with certain radiographic findings in asymptomatic teeth. Our results should be interpreted with caution because the quality of the underlying data is limited.

Experimental Abscess Formation Caused by Human Dental Plaque

Human dental plaque consists of a wide variety of microorganisms, some of which are believed to cause systemic infections, including abscesses, at various sites in the body. To confirm this hypothesis experimentally, we examined the abscess-forming ability of native dental plaque in mice, the microbial features of the infectious locus produced by the plaque, and the anti-phagocytic property of microbial isolates. Aliquots of a suspension of supragingival dental plaque containing 6 x 10(6) colony-forming unit of bacteria were injected subcutaneously into the dorsa of mice. Abscess formation was induced in 76 of 85 mice using ten different plaque samples. Thirteen microorganisms were isolated from pus samples aspirated from abscess lesions. The microbial composition of pus, examined in 17 of 76 abscesses, was very simple compared to that of the plaque sample that had induced the abscess. The majority of the isolates belonged to the Streptococcus anginosus group, normally a minor component of plaque samples. S. anginosus was the most frequently detected organism and the most prevalent in seven abscesses, and Streptococcus intermedius and Streptococcus constellatus were predominant in one and three abscess samples, respectively. Each isolate of S. anginosus group produced abscesses in mice, and heat-treated supragingival dental plaque influenced the abscess-forming ability of S. anginosus isolate. These isolates possessed a high antiphagocytic capacity against human polymorphonuclear leukocytes. Our results suggest that human supragingival dental plaque itself is a source of the infectious pathogens that cause abscess formation.

Oral microbiota and systemic disease

It is well known that bacteria are the primary cause of infectious diseases, however, evidence is emerging that these organisms are also indirectly responsible for several diseases including cancer and rheumatoid arthritis. The oral cavity is home to several million bacteria that can cause two major diseases-periodontitis and caries. The relationship between periodontopathic bacteria and systemic diseases has been explored for several years. The concept of the oral cavity as a source of distant infection has been debated for at least a century. This review will discuss the historic aspects of the development of the focal infection theory, the reasons for its demise, its re-emergence and current status.

Prevalence of apical periodontitis and quality of root canal fillings in population of Zagreb, Croatia: a cross-sectional study

AIM

To determine the prevalence of apical periodontitis and assess the quality of endodontic fillings in the population of the city of Zagreb, Croatia.

METHODS

A total of 1462 orthopantomograms from new patients at 6 different dental practices was analyzed during 2006 and 2007. The presence of periapical lesions was determined by using the periapical index score (PAI). The quality of endodontic fillings was assessed according to the filling length and homogenicity. Data were analyzed using t test and ANOVA with Scheffe post-hoc test.

RESULTS

There were 75.9% of participants with endodontically treated teeth and 8.5% of all teeth were endodontically treated. Only 34.2% of endodontically treated roots had adequate root canal filling length, while 36.2% of root canal fillings had homogenous appearance. From the total number of teeth with intracanal post, 17.5% had no visible root canal filling. Using PAI 3 as a threshold value for apical periodontitis, periapical lesions were detected in 8.5% of teeth. Adequate quality of root canal fillings was associated with a lower prevalence of periapical lesions.

CONCLUSION

We found a large proportion of endodontically treated teeth with apical periodontitis and a correlation between the quality of endodontic filling and the prevalence of periapical lesions. This all suggests that it is necessary to improve the quality of endodontic treatment in order to reduce the incidence and prevalence of apical periodontitis.

Interferon gamma in the etiology of atherosclerosis and periodontitis

Clinical observations and a few research reports seem to suggest that intraoral infection as well as periodontal teeth could potentially lead to systemic infections including atherosclerosis. The aim of our investigations was to determine whether periodontal disease might aggravate atherosclerosis and whether interferon-gamma (IFNG), widely recognized as a potent multifunctional cytokine, might serve as a marker of the process. This is the first research based on tissue material such as atheromata and periodontal pocket granulation tissue. The study population consisted of 15 patients with periodontitis and atherosclerosis. Control group comprised 15 non-atherosclerotic patients with periodontitis. IFNG, IFNGR1 and IFNGR2 expression was analysed using qRT-PCR profiling in the inflammatory granulation tissue and atheroma. Granulation tissue samples obtained from non-atherosclerotic group showed a significant increase in IFNG and a decrease of IFNGR1, IFNGR2 expression whereas granulation tissue and atheromata of patients with systemic disease demonstrated lower IFNG and higher IFNGR1 and IFNGR2 expression.

Gemella morbillorum in primary and secondary/persistent endodontic infections

OBJECTIVE

To investigate the presence of Gemella morbillorum by culture or nested PCR in primary and secondary/persistent endodontic infections.

STUDY DESIGN

Microbial samples were taken from 50 cases with primary and 50 cases with secondary/persistent endodontic infections. Microbiologic techniques were used for culture and identification. The DNA extracted from the samples was analyzed for the presence of the target species using species-specific primers.

RESULTS

Culture and polymerase chain reaction (PCR) identified the species in 23 and 77, respectively, of 100 root canals. Culture yielded the test organism in 19 of 50 (38%) of root canal samples from primary and in 4 of 50 (8%) from secondary/persistent infections. PCR yielded the test organisms in 41 of 50 (82%) and 36 of 50 (72%) of the, respectively, primary and secondary/persistent root canal infections studied.

CONCLUSION

Gemella morbillorum was identified more frequently in primary endodontic infections than in secondary/persistent ones. A higher frequency of the target species was detected by PCR than by culture.

Endodontics and infective endocarditis – is antimicrobial chemoprophylaxis required?

The purpose of this review is to evaluate the evidence implicating nonsurgical endodontic procedures in inducing infective endocarditis (IE). The literature is reviewed and findings about dental procedures that elicit bacteraemia [in particular root canal treatment (RCT)], sequelae of bacteraemia, relationship between IE and RCT and variation between antibiotic prophylaxis (AP) guidelines are highlighted. At present, there is still significant debate as to which dental procedures require chemoprophylaxis and what antibiotic regimen should be prescribed. Currently, there are insufficient primary data to know whether AP is effective or ineffective against IE. Practitioners are bound by current guidelines and medico-legal considerations. Thus, the profession requires clear, uniform guidelines that are evidence-based.

Consequences of and strategies to deal with residual post-treatment root canal infection

Bacterial sampling of prepared root canals is used to determine the presence and character of the remaining microbiota. However, it is likely that current sampling techniques only identify organisms in the main branches of the root canal system whereas it is unlikely that they can sample areas beyond the apical end-point of preparation and filling, or in lateral canals, canal extensions, apical ramifications, isthmuses and within dentinal tubules. Thus, it may be impossible by current techniques to identify residual post-treatment root canal infection. In histologic observations of root apices, bacteria have been found in inaccessible inter-canal isthmuses and accessory canals often in the form of biofilms. There is no in vivo evidence to support the assumption that these bacteria can be entombed effectively in the canal system by the root filling and thus be rendered harmless. As a consequence of this residual root infection, post-treatment apical periodontitis, which may be radiographically undetectable, may persist or develop as a defence mechanism to prevent the systemic spread of bacteria and/or their byproducts to other sites of the body. Histologic observation of root apices with surrounding bone removed from either patients or human cadavers has demonstrated that post-treatment apical periodontitis is associated with 50-90% of root filled human teeth. Thus, if the objective of root canal treatment is to eliminate apical periodontitis at a histological level, current treatment procedures are inadequate. It is essential that our knowledge of the local and systemic consequences of both residual post-treatment root infection and post-treatment apical periodontitis be improved. The continued development of treatments that can effectively eliminate root infection is therefore a priority in clinical endodontic research. Post-treatment disease following root canal treatment is most often associated with poor quality procedures that do not remove intra-canal infection; this scenario can be corrected via a nonsurgical approach. However, infection remaining in the inaccessible apical areas, extraradicular infection including apically extruded dentine debris with bacteria present in dentinal tubules, true radicular cysts, and foreign body reactions require a surgical intervention.

C-Reactive Protein and Serum Amyloid A in a Canine Model of Chronic Apical Periodontitis

Increased levels of systemic inflammatory markers have been observed in patients with chronic dental diseases, such as marginal periodontitis. A canine model was used to determine if a systemic inflammatory response was evident during chronic apical periodontitis (CAP). Dental pulps in 10 dogs were exposed and infected with dental plaque to induce CAP. Blood samples were drawn preoperatively and postinfection when CAP was seen radiographically. In three of the 10 dogs, an intravenous challenge of Porphyromonas gingivalis A7436 was given subsequent to the development of CAP. An ELISA assay was used to measure the levels of C-reactive protein (CRP) and serum amyloid A (SAA) as markers of systemic inflammation. During CAP the levels of CRP and SAA were not statistically different from the preoperative values as determined by the Friedman test (p < 0.05). One dog, which had an unplanned trauma-induced laceration of the paw 2 days before blood sampling, showed a 40-fold increase in CRP. The 3 dogs challenged by intravenous P. gingivalis A7436 showed elevated levels of CRP, consistent with an acute phase response. These data demonstrate that the canine model provides a useful means for studying the systemic effects of apical periodontitis, and show that CAP is not associated with elevated CRP or SAA.

Quantification of endotoxins in necrotic root canals from symptomatic and asymptomatic teeth

The purpose of this investigation was to quantify the concentration of endotoxin in necrotic root canals and investigate the possible relationship between the concentration of endotoxin and endodontic signs and symptoms. Samples were collected from root canals of 50 patients requiring endodontic treatment due to necrosis of the pulpal tissue. Anaerobic techniques were used to determine the number of c.f.u. in each sample. A quantitative chromogenic Limulus amoebocyte lysate assay was used to measure the concentration of endotoxin in each sample. The presence of c.f.u. was detected by culture in all samples (range 10(2)-5x10(6)). In samples from cases of patients with spontaneous pain, the mean c.f.u. was 1.43x10(6) while in asymptomatic cases it was 9.1x10(4). Endotoxin was present in all the samples studied [range 2390.0-22100.0 endotoxin units (EU) ml-1]. The mean concentration of endotoxin in samples from patients with spontaneous pain was 18540.0 EU ml-1 while in asymptomatic cases it was 12030.0 EU ml-1. Asymptomatic cases generally had lower levels of endotoxin (i.e. a negative association). A positive association was found between endotoxin and symptomatic cases (e.g. spontaneous pain, tenderness to percussion, pain on palpation, swelling and purulent exudates). This study showed that endotoxin is present in high concentrations in root canals of symptomatic teeth. There was a positive correlation between the concentration of endotoxin in the root canal and the presence of endodontic signs and symptoms.

Light microscopic study of periapical lesions associated with asymptomatic apical periodontitis

The purpose of the study has been to evaluate the degree of chronic inflammation in tissues surrounding the apex of the tooth root in patients with apical periodontitis in the remission phase. The material included 37 apical granulomas and radicular cysts obtained as a result of apiectomy, and 20 teeth which were removed together with the focus of the periapical inflammation. Routine histological techniques, as well as the immunofluorescent and immuno-chemical methods were used to examine the material. Despite the absence of clinical symptoms in 23 of 57 cases, the morphological signs of chronic inflammation were observed in the apical area of the tooth root. Morphological signs of viral invasion of epithelial and stromal cells in the radicular cyst wall were revealed in six cases. The presence of the virus of Herpes simplex I in epithelial cells (five cases) and adenoviral invasion (one case) was confirmed by immuno-fluorescent and immuno-chemical methods. Histological examination often reveals morphological signs of an active inflammatory process in the periapical tissues of patients treated during clinical remission. In our opinion, the presence of viruses in the epithelial cells of the radicular cyst may contribute to the persistence of the active stage of the inflammatory process.

Canal preparation with Hero 642 rotary Ni-Ti instruments compared with stainless steel hand K-file assessed using computed tomography

AIM

To compare ex vivo root canal preparation with conventional stainless steel K-files and Hero 642 rotary Ni-Ti instruments.

METHODOLOGY

Mesiobuccal canals of 20 maxillary first molars (with angles of curvature between 25 degrees and 35 degrees ) were used. After preparation with Hero 642 rotary instruments and stainless steel K-files, the amount of transportation that occurred was assessed using computed tomography. The teeth were scanned by computed tomography before instrumentation. One millimetre thick slices were prepared from the apical end point to the pulp chamber. The first two sections were 3 mm from the apical end of the root (apical level) and 3 mm below the orifice (coronal level). A further section (mid-root level) was recorded, dividing the distance between the sections of apical and coronal levels into two equal lengths. Ten teeth were instrumented using Hero 642 rotary instruments and another 10 teeth were instrumented using stainless steel K-files. Following the completion of the instrumentation, the teeth were again scanned and compared with the cross-sectional images taken prior to canal preparation. Amount of transportation and centreing ability was assessed. Student's t-test was used for statistical analysis.

RESULTS

Less transportation occurred with Hero 642 rotary instruments than stainless steel K-files at the mid-root and coronal levels (mid-root: P < 0.05 and coronal: P < 0.001). Hero 642 rotary instruments had better centreing ability than K-files at all three levels (apical: P < 0.05, mid-root: P < 0.05 and coronal: P < 0.001).

CONCLUSIONS

Hero 642 rotary instruments transported canals less, especially at the middle and coronal thirds of the root canals than stainless steel K-files. Hero 642 instruments had better centreing ability.

Additive antimicrobial activity of calcium hydroxide and chlorhexidine on common endodontic bacterial pathogens

It is an established procedure to use calcium hydroxide [Ca(OH)2] as a therapeutic component to achieve sterilization of infected root canals. Unfortunately, some bacterial species are relatively resistant to Ca(OH)2 and are therefore associated with treatment failures. The objective of this study was to identify combinations of substances that improve antimicrobial activity. Ca(OH)2 was used as a suspension or as a component of gutta-percha points. Efficacy of killing was compared for (a) Ca(OH)2 suspension alone; (b) zinc oxide (ZnO) points alone; (c) Ca(OH)2 suspension combined with ZnO points; (d) Ca(OH)2 suspension combined with ZnO/chlorhexidine points; and (e) Ca(OH)2 points combined with ZnO/chlorhexidine points. Common endodontopathogenic bacterial species (Enterococcus faecalis, Fusobacterium nucleatum, Peptostreptococcus micros, Porphyromonas gingivalis, Streptococcus intermedius) in pure cultures served as target organisms. In the in vitro assay, the antibacterial substances and approximately 10(7) colony forming units of test bacteria were co-incubated in diluted human serum under growth conditions appropriate for the single bacterial species. Samples were taken on days 0, 1, 2, 4, 7, and 14 of incubation and viable counts determined. Gram-negative bacteria were sufficiently killed by Ca(OH)2 alone. Combinations with other agents did not improve the killing kinetics. For the inactivation of the Gram-positive bacteria P. micros and S. intermedius, a combination of Ca(OH)2 and ZnO/chlorhexidine, killed the bacteria faster than Ca(OH)2 alone. For E. faecalis, combining Ca(OH)2 suspension with ZnO/chlorhexidine points lead to a faster decrease in the overall number of viable bacteria, but no test conditions lead to the complete loss of culture viability. The results of this study support the use of a combination of Ca(OH)2 and chlorhexidine for faster eradication of P. micros and S. intermedius from infected root canals.

Endodontic infections: concepts, paradigms, and perspectives

Overwhelming evidence indicates that periradicular diseases are infectious disorders. The question now is no longer whether microorganisms are involved in the pathogenesis of such diseases, but which specific microbial species are. The list of microorganisms involved in periradicular diseases keeps expanding and has the potential to become increasingly more accurate during the next few years. Molecular methods have contributed significantly to the knowledge about the microbial species involved. Undoubtedly, a great deal of additional research is needed to define the specific role played by suspected endodontic pathogens in the etiology of each form of periradicular disease and to determine the best therapeutic measures for the pathogen's eradication. In addition, there is an emergent need to define markers that permit the clinician to know when he or she should conclude the treatment and to predict the outcome of the treatment. Although endodontic procedures and some acute endodontic infections can cause bacteremia, there is no clear evidence that microorganisms from the root canal can cause diseases in remote sites of the body. However, there is a risk in some compromised individuals, and prophylactic measures should be taken. Prescription of systemic antibiotics in endodontic therapy is rarely necessary. Because of the emergence of bacterial resistance against most known antibiotics, their use in endodontics should be highly limited and restricted to a few cases.

Hemisection for treatment of an advanced endodontic-periodontal lesion: a case report

AIM

To emphasize the importance of primary endodontic treatment when dealing with endo-perio lesions and to demonstrate the considerable healing potential of the endodontic aspect.

CASE REPORT

After several years of unsuccessful symptomatic periodontal treatment, an advanced endo-perio lesion on a right-mandibular first molar was successfully treated by root-canal treatment and hemisection after the re-evaluation of the lesion. This successful treatment appeared to have a positive effect on the patient's general well-being.

KEY LEARNING POINTS

The origin of a combined endo-perio lesion is indicated by its clinical and radiographic appearance. The periodontal situation is often misinterpreted. The prognosis for the endodontic element of treatment is excellent. Local pathologic processes in the oral cavity may affect a patient's general health.

Penetration of propylene glycol into dentine

AIM

This study aimed to evaluate penetration of propylene glycol into root dentine.

METHODOLOGY

Safranin O in propylene glycol and in distilled water were introduced into root canals with and without artificial smear layer. Dye diffusion through dentinal tubules was determined spectrophotometrically. The time required for dye to exit through the apical foramen using propylene glycol and distilled water as vehicles was also determined. The extent and areas of dye penetration on the split surfaces of roots were assessed using Adobe Photoshop and NIH Image Software.

RESULTS

Propylene glycol allowed dye to exit faster through the apical foramen. The area and depth of dye penetration with propylene glycol was significantly greater than with distilled water (P < 0.0001). Smear layer significantly delayed the penetration of dye.

CONCLUSION

Propylene glycol delivered dye through the root canal system rapidly and more effectively indicating its potential use in delivering intracanal medicaments.

The perceived benefit of endodontic retreatment

AIM

There is substantial variation amongst dentists in the management of symptom-free periapical lesions in root-filled teeth. It has been suggested that this variation can be understood as clinicians' choice of different cut-off points on a continuous periapical health scale (the 'Praxis Concept (PC) theory'). Based on this suggestion, an individual's inclination to propose retreatment can be expressed in the Retreatment Preference Score (RPS). In the present study it was hypothesized that: (i) the PC theory is valid amongst experienced endodontists; and that (ii) interindividual variation in RPS can be explained by a corresponding variation in the perceived benefit of endodontic retreatment.

METHODOLOGY

The RPS was determined for 16 experienced Swedish endodontists. The retreatment benefit (RTB) was defined as the gain in utility when a root-filled tooth with a persistent periapical lesion ('health state B') moved to a state where the lesion had healed ('health state A'). For each individual the utility values of the two health states were measured by means of the standard gamble technique.

RESULTS

The RPS and RTB were found to be subjected to substantial inter- and intrarater variation. The decision makers acted in accordance with the PC theory. No significant correlation between RPS and RTB was detected.

CONCLUSIONS

Findings suggest that the PC theory is valid amongst endodontic experts. The study did not support the notion that the more potential utility that could be produced, the more the individual dentist should tend to perform retreatment. However, alternative consequentialist strategies focusing low risk taking may be involved.