Root anatomy and canal configuration of the permanent mandibular first molar: Clinical implications and recommendations

Root canal anatomy may present clinicians with a complex clinical challenge that requires diagnostic approaches, access modification, and clinical skills to successfully localize, negotiate, disinfect, and seal the root canal system. This article discusses the clinical implications of endodontic therapy on permanent mandibular first molars. The number of roots on the mandibular first molar is directly related to ethnicity. Canal morphology has a significant effect on treatment protocol: Mesial roots present two canals on a regular basis, adopting 2-2 and 2-1 as the most common configurations. A third canal is present in 2.6% of the population. The most common configuration in the distal root is type I (62.7%), followed by type II (14.5%) and type IV (12.4%). Diagnosis and treatment of complex root canal systems often require specialized training that may be beyond the scope of the average general practitioner. Access modifications are required to find extra roots and/or canals. The instrumentation of the third root requires a different access and small, flexible instruments, given the curvature that is usually present buccally in the apical third. The incidence of isthmuses is 55% in the mesial root and 20% in the distal root. This anatomical configuration should be taken into consideration during endodontic treatment as well as during periapical surgery.0.710 JCR (2012) Q4, 68/83 Dentistry, oral surgery & medicin

Effect of EDTA, sonic, and ultrasonic activation on the penetration of sodium hypochlorite into simulated lateral canals: An in vitro study

The purpose of this study was to evaluate the penetration of 5.25% sodium hypochlorite alone or in combination with 17% EDTA in simulated lateral canals using sonic and ultrasonic activation. Four hundred and eighty simulated lateral canals were created in 80 single rooted cleared teeth by inserting 06 K-files at 2, 4.5 and 6 mm of working length. Samples were mounted on clear silicon to simulate the presence of surrounding periodontal tissues and its effects on fluid dynamics and then randomly assigned to four experimental groups: 1 (n = 20) 5.25% NaOCl + sonic activation; 2 (n = 20) 5.25% NaOCl + ultrasonic activation; 3 (n = 20) 5.25% NaOCl + 17% EDTA + sonic activation and 4 (n = 20) 5.25% NaOCl + 17% EDTA + ultrasonic activation. Sonic activation was delivered using the Endoactivator® inserted 2 mm short of working length and activated for 1 minute. Ultrasonic activation was performed with a stainless steel ultrasonic file inserted 2 mm short of working length and passively activated for 3 cycles of 20 seconds each. Samples were evaluated by direct observation of the images recorded under the operating microscope and by radiographic evaluation after irrigation with a contrast solution. Sonic and ultrasonic activation resulted in a better irrigation of the lateral canals at 4.5 and 2 mm from working length compared to traditional needle irrigation alone. Traditional needle irrigation alone demonstrated significantly less penetration of irrigant into the lateral canals and was limited to the level of penetration of the needle. In conclusion, the addition of EDTA did not result in better penetration of irrigants into the lateral canals.Sin financiación2.953 JCR (2009) Q1, 5/64 Dentistry, oral surgery & medicineUE

Root anatomy and canal configuration of the permanent mandibular first molar: A systematic review

Introduction: The main goal of endodontic therapy is to prevent or heal apical periodontitis. However, root canal anatomy might present a clinical challenge directly related to the treatment outcome. The purpose of this study was to review published literature related to root anatomy and root canal configuration of the permanent mandibular first molar. Methods: An exhaustive search was undertaken to identify published literature related to the root anatomy and root canal morphology of the permanent mandibular first molar by using key words. The search of the MEDLINE database included all publications from 1966-May 2010. Selected articles were then obtained and reviewed. Data evaluated and summarized in the data sheet included methodology, population, number of teeth per study (power), number of root canals, type of root canal configuration, and identification of number of apical foramina. Results: Forty-one studies were identified including a total of 18,781 teeth. The incidence of a third root was 13% and was strongly correlated with the ethnicity of the studied population. Three canals were present in 61.3%, 4 canals in 35.7%, and 5 canals in approximately 1%. Root canal configuration of the mesial root revealed 2 canals in 94.4% and 3 canals in 2.3%. The most common canal system configuration was Vertucci type IV (52.3%), followed by type II (35%). Root canal configuration of the distal root revealed type I configuration in 62.7%, followed by types II (14.5%) and IV (12.4%). The presence of isthmus communications averaged 54.8% on the mesial and 20.2% on the distal root. Conclusions: The number of roots on the mandibular first molar is directly related to ethnicity. Root canal morphology and configuration might present the clinician with a complex anatomy requiring more diagnostic approaches, access modifications, and clinical skills to successfully localize, negotiate, disinfect, and seal the root canal system. (J Endod 2010;36:1919-1931)3.291 JCR (2010) Q1, 3/77 Dentistry, oral surgery & medicin

Cohort Study of Airway Mycobiome in Adult Cystic Fibrosis Patients: Differences in Community Structure between Fungi and Bacteria Reveal Predominance of Transient Fungal Elements.

The respiratory mycobiome is an important but understudied component of the human microbiota. Like bacteria, fungi can cause severe lung diseases, but their infection rates are much lower. This study compared the bacterial and fungal communities of sputum samples from a large cohort of 56 adult patients with cystic fibrosis (CF) during nonexacerbation periods and under continuous antibiotic treatment. Molecular fingerprinting based on single-strand conformation polymorphism (SSCP) analysis revealed fundamental differences between bacterial and fungal communities. Both groups of microorganisms were taxonomically classified by identification of gene sequences (16S rRNA and internal transcript spacer), and prevalences of single taxa were determined for the entire cohort. Major bacterial pathogens were frequently observed, whereas fungi of known pathogenicity in CF were detected only in low numbers. Fungal species richness increased without reaching a constant level (saturation), whereas bacterial richness showed saturation after 50 patients were analyzed. In contrast to bacteria, a large number of fungal species were observed together with high fluctuations over time and among patients. These findings demonstrated that the mycobiome was dominated by transient species, which strongly suggested that the main driving force was their presence in inhaled air rather than colonization. Considering the high exposure of human airways to fungal spores, we concluded that fungi have low colonization abilities in CF, and colonization by pathogenic fungal species may be considered a rare event. A comprehensive understanding of the conditions promoting fungal colonization may offer the opportunity to prevent colonization and substantially reduce or even eliminate fungus-related disease progression in CF

High Individuality of Respiratory Bacterial Communities in a Large Cohort of Adult Cystic Fibrosis Patients under Continuous Antibiotic Treatment.

Routine clinical diagnostics of CF patients focus only on a restricted set of well-known pathogenic species. Recent molecular studies suggest that infections could be polymicrobial with many bacteria not detected by culture-based diagnostics

Apical negative pressure irrigation versus conventional irrigation plus triantibiotic intracanal dressing on root canal disinfection in dog teeth

Objective. The aim of this study was to compare in vivo the efficacy of 2 root canal disinfection techniques (apical negative pressure irrigation versus apical positive pressure irrigation plus triantibiotic intracanal dressing) in immature dog teeth with apical periodontitis. Study design. Two groups of root canals with pulp necrosis and apical periodontitis were evaluated according to the disinfection technique: group 1: apical negative pressure irrigation (EndoVac system); and group 2: apical positive pressure irrigation (conventional irrigation) plus triantibiotic intracanal dressing. The first sample (S1) was collected after lesions were radiographically visible, and the second sample (S2) was collected after apical negative pressure irrigation (group 1) or conventional irrigation/triantibiotic dressing (group 2). All samples were seeded in a culture medium for anaerobic bacteria. Colony-forming unit counts were analyzed statistically by the Mann-Whitney test (alpha = .05). Results. Microorganisms were present in 100% of canals of both groups in S1. In S2, microorganisms were absent in 88.6% of group 1`s canals and 78.28% of group 2`s canals. There was no significant difference between the groups in either S1 (P = .0963) or S2 (P = .0566). There was significant (P < .05) bacterial reduction from S1 to S2 in both groups. Conclusion. In immature teeth with apical periodontitis, use of the EndoVac system can be considered to be a promising disinfection protocol, because it provided similar bacterial reduction to that of apical positive pressure irrigation (conventional irrigation) plus intracanal dressing with the triantibiotic paste, and the use of intracanal antibiotics might not be necessary. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010;109:e42-e46

Multidimensional Scaling (MDS) plots from bacterial community composition observed in 72 sputum samples.

<p>Bubbles indicate relative abundances of the 4 most prevalent OTUs in the cohort: <i>P</i>. <i>aeruginosa</i> in green, <i>S</i>. <i>aureus</i> in orange, alpha-hemolytic <i>Streptococcus</i> (<i>Streptococcus</i> -1) in yellow, <i>R</i>. <i>mucilaginosa</i> in blue. 2D Stress values are given in each plot and reveal moderate stress. <b>(A)</b> Merged bubble plots from all four dominant OTUs, coloured bubbles indicating the individual abundances. <i>P</i>. <i>aeruginosa</i> as well as <i>S</i>. <i>aureus</i> have priority, whereas the abundances for <i>R</i>. <i>mucilaginosa</i> and alpha-hemolytic <i>Streptococcus</i> are in the background. (<b>B)</b> Individual MDS plots for each dominant OTU. Numbers indicate individual patients. Letters are according the order of sputum collection.</p