Association between the presence of distolingual root in mandibular first molars and the presence of C-shaped mandibular second molars: a CBCT study in a Taiwanese population.

OBJECTIVES: The purpose of this study was to assess the prevalence of C-shaped canals in permanent mandibular second molars (SMs) and to determine whether its appearance was associated with the presence of distolingual root (DLR) in permanent mandibular first molars (FMs). METHOD AND MATERIALS: Three hundred and eighty patients were qualified for evaluation of their FMs and SMs using cone beam computed tomography. The prevalence, distribution pattern, external root morphology, and the internal root canal anatomy of the examined molars were recorded and analyzed. Furthermore, the association between the root canal configurations of SMs and the appearance of DLR in FMs was also assessed. RESULTS: The prevalence of SMs with C-shaped root canals was 44.7%. The most common root canal configuration type of the one-rooted SMs with C-shaped anatomy was C3 (45.6%), followed by C2 and C1. The frequency of C-shaped canals in SMs was 45.4% in Non-DLR group, 52.8% in unilateral DLR group, and 33.9% in bilateral DLR group, respectively. Moreover, the prevalence of C-shaped root canals in SMs with the presence of bilateral DLRs in FMs was significantly lowered. CONCLUSION: The association between the presence of DLR in FMs and C-shaped canal configurations in neighboring SMs was surveyed, and the prevalence of C-shaped root canals in SMs with the presence of bilateral DLRs in FMs was found to be significantly lowered.

Nonsurgical root canal therapy of large cyst-like inflammatory periapical lesions and inflammatory apical cysts.

It is a general belief that large cyst-like periapical lesions and apical true cysts caused by root canal infection are less likely to heal after nonsurgical root canal therapy. Nevertheless, there is no direct evidence to support this assumption. A large cyst-like periapical lesion or an apical true cyst is formed within an area of apical periodontitis and cannot form by itself. Therefore, both large cyst-like periapical lesions and apical true cysts are of inflammatory and not of neoplastic origin. Apical periodontitis lesions, regardless of whether they are granulomas, abscesses, or cysts, fail to heal after nonsurgical root canal therapy for the same reason, intraradicular and/or extraradicular infection. If the microbial etiology of large cyst-like periapical lesions and inflammatory apical true cysts in the root canal is removed by nonsurgical root canal therapy, the lesions might regress by the mechanism of apoptosis in a manner similar to the resolution of inflammatory apical pocket cysts. To achieve satisfactory periapical wound healing, surgical removal of an apical true cyst must include elimination of root canal infection.

Endosseous implants versus nonsurgical root canal therapy: a systematic review of the literature.

For this article, the authors identified and reviewed the current literature, addressing two treatment options for endodontically involved teeth: root canal therapy and restoration versus extraction and the placement of a dental implant. The literature was evaluated as a basis for making treatment decisions. PubMed was queried for all studies that compared nonsurgical root canal therapy (NSRCT) and restoration with the extraction of teeth and placement of a dental implant. This search was supplemented by searching the bibliographies of these studies to ensure that all relevant studies were included. A total of 38 studies were found that directly compared NSRCT and restoration with extraction and placement of a dental implant. The literature is discussed in terms of outcomes for both treatment options, considerations in treatment plan decision-making, or the opinions of the authors.

One-appointment endodontic therapy: biological considerations.

BACKGROUND: The authors conducted a literature review to present the best available biological evidence concerning one-appointment endodontic therapy for asymptomatic teeth with apical periodontitis. TYPES OF STUDIES REVIEWED: Because of recent advances in technology, such as rotary engines and nickel-titanium instruments, some practitioners are performing one-appointment endodontic therapy for asymptomatic teeth with apical periodontitis. The authors reviewed the literature, which revealed only a small number of randomized, controlled clinical trials that have been conducted on one-appointment versus multiple-appointment endodontic therapy. RESULTS: As the apical canal preparation is enlarged, a greater percentage of bacteria is eradicated from infected root canals. In addition, sufficiently large apical root canal enlargement facilitates the delivery of antimicrobial irrigant to the apical portion of the canal. However, an association between positive or negative preobturation root canal culture results and the outcome of endodontic treatment has not been well-established. CLINICAL IMPLICATIONS: The best available evidence, based on a systematic literature review, indicates that one-appointment endodontic therapy may be feasible in selected cases of apical periodontitis in asymptomatic teeth. However, additional randomized, controlled clinical trials are required.

Histological study of periradicular tissue responses to uninfected and infected devitalized pulps in dogs.

Uninfected necrotic tissue, such as that which follows a myocardial or cerebral infarct, is capable of inducing an inflammatory reaction. Eventually, the infarct is organized by granulation tissue. Why then, does uninfected devitalized pulp tissue, such as in traumatized teeth, not cause periradicular inflammation and does not become organized by granulation tissue? Four beagle dogs were used in this experiment. A total of 48 teeth, which included 24 maxillary and 24 mandibular incisors, were aseptically devitalized, leaving residual pulp tissues in the root canals, and equally divided into two groups. Group A (24 uninfected): A sterile cotton pellet was placed deep into the canal orifice before the pulp chamber and access opening were closed with a layer of zinc-oxide eugenol cement followed by glass ionomer cement. Group B (24 infected): The teeth were left open to the oral cavity for 7 days and then closed with a cotton pellet and zinc-oxide eugenol and glass ionomer cement. The animals were sacrificed one year after the experiment and prepared for histological examination of periradicular tissue responses to uninfected and infected devitalized pulp tissues. The results indicate that uninfected devitalized pulp tissues did not continuously release inflammatory mediators and cause persistent periradicular inflammation over a period of one year. However, infected devitalized pulp tissues induced various degrees of periradicular inflammation. Only the apical few millimeters of uninfected devitalized pulp tissue in the root canals were organized by granulation tissue from vital periodontal ligament tissue.

Do procedural errors cause endodontic treatment failure?

BACKGROUND: This article reviews the effect of endodontic procedural errors, such as underfilling, overfilling, root perforations and separated instruments, on the outcome of endodontic therapy. TYPES OF STUDIES REVIEWED: Filling the root canal more than 2 millimeters from the radiographic apex (underfilling) or beyond the radiographic apex (overfilling), perforations of the root canal system and instrument separation are possible complications of endodontic therapy. Although these procedural errors may have different causes, they all may affect the outcome of treatment. RESULTS: Endodontic procedural errors are not the direct cause of treatment failure; rather, the presence of pathogens in the incompletely treated or untreated root canal system is the primary cause of periradicular pathosis. Procedural errors typically are due to several factors. Among them is a lack of understanding of the root canal anatomy, the principles of mechanical instrumentation and tissue wound healing. CLINICAL IMPLICATIONS: Procedural errors impede endodontic therapy, thus increasing the risk of treatment failure, especially in teeth with necrotic pulps and periradicular lesions. However, procedural errors often are preventable.

The crisis in endodontic education: current perspectives and strategies for change.

The current status of dental education in the United States and Canada with respect to faculty recruitment and retention is reviewed; poor salaries and lack of interest are major reasons for dwindling numbers. The pros and cons of an academic career and what the American Association of Endodontists' (AAE) and other constituencies have done to help alleviate the problem are presented. The results of an on-line survey to full-time endodontic educators on their perspectives on education are presented; personal fulfillment, sharing knowledge, giving back to the profession, and passion for teaching were reasons for teaching whereas income disparity, lack of mentoring, and high demands of the job were reasons against an academic career. The final phase of the paper proposes various strategies on how the AAE and its membership, dental schools, and the American Board of Endodontics (ABE) can further work together to alleviate the critical problems facing endodontic education.