ENDO, 01/2015

Aim: The aim of this article was to review the effect of chlorhexidine (CHX) against other irrigants on the bond strength between resin-bonded root canal fillings and dentin. Materials and methods: A literature analysis was performed using the Web of science core collection, Biosis citation index, Biosis preview and Medline electronic databases (articles published in English up to 8 May 2014) with the search terms and combinations as follows: 'chlorhexidine AND dentin OR sealer OR root canal filling OR bond strength'. Publications were included if the effects of chlorhexidine irrigation on the bond strength between bonded root canal fillings and dentin were stated and if other irrigants were compared. Results: The search identified 1296 publications of which eight fulfilled the review's inclusion criteria. Conclusions: The effect of using CHX as an irrigant depends on the other preparations used as part of the irrigation protocol. The available data suggests that a final CHX irrigant enhances dentin bond strength if sodium hypochlorite is the main irrigant, and when CHX gel is used together with phosphoric acid. There is, however, insufficient data to enable a sound conclusion to be reached regarding the effect of CHX as a main irrigant. Keywords: bond strength, chlorhexidine, resin-bonded, root canal filling, root canal irrigation

Despite its high prevalence in adult populations, endodontic infections in individuals with systemic involvement, such as Human Immunodeficiency virus (HIV) infection, have been the subject of only a few studies. The aim of the present review was to answer the following questions: 1) Does highly active antiretroviral therapy (HAART) alter the clinical manifestation of endodontic infections? 2) Does HIV infection interfere in the development/repair of periradicular lesions? 3) Can HIV infection promote changes in the endodontic microbiota? Although there is plenty of information available regarding the different aspects of the endodontic infection, few studies were performed in HIV-infected individuals. Hence, the true impact of HIV infection on the clinical, immunological and microbiological aspects of the endodontic infection still needs to be clarified. In fact, it is mandatory to understand all aspects associated with endodontic infection and HIV infection in order to establish an adequate diagnosis, prognosis and endodontic treatment plan. The present review suggests that the clinical aspects of endodontic infections in HIV patients have changed with the introduction of HAART; HIV infection does not interfere in the development/repair of periradicular lesions; there is a significant difference in the endodontic microbiota found in HIV- and non-HIV-infected patients, with regard to both the prevalence and the proportion of specific microorganisms. Keywords: endodontic treatment, highly active antiretroviral therapy, HIV infection, periradicular lesions, viral load

Aim: To determine and classify the position of the mesial root canal orifices on the pulp chamber floor and examine their possible correlation with the radicular pattern in mandibular first molars. Materials and Methods In total, 110 extracted mandibular first molars were obtained and the positions of the orifices and the radicular pattern were observed using an operating microscope. Results: Of the mesial root canals, 61 (55.5%) had an independent pattern and 49 (44.5%) had a confluent radicular pattern. In canal orifices with symmetrical positions on the pulp chamber floor, the interorificial distance was key: 88% of canals were confluent at distances between 1 and 2 mm and 95.3% were independent at distances > 2 mm. In asymmetric positions, the canals had an independent pattern regardless of distance, with a percentage of 82.4%. Analysis of the independent and confluent radicular patterns showed a significant difference with the interorificial distance (P = 0.0004). Conclusion: A significant correlation was seen between the position of the mesial root canal orifices on the pulp chamber floor and an independent or confluent radicular pattern in the mandibular first molars. Keywords: dental operating microscope, mandibular molars, root canal morphology, root canal pattern

Aim: To evaluate the ex vivo effectiveness of four different rotary systems in removing filling material from curved root canals, and to determine the time required to do so. Materials and methods: Forty-eight curved mesiobuccal root canals of first and second mandibular molars were prepared, obturated, and randomly divided into four groups (n = 12), according to the retreatment rotary system used for filling material removal, as follows: R-Endo, Mtwo Retreatment, D-RaCe, and ProTaper. The amount of remaining filling material was assessed in buccolingual and mesiodistal radiographs using Image Tool 3.0 software. The Kruskal-Wallis test was used to compare differences between the groups. The time required for filling material removal was recorded using a digital stopwatch. Results: There was no statistically significant difference between the groups with regard to the amount of remaining filling material (P > 0.05). Filling material removal using Mtwo files (mean 3.30 min) was significantly faster than using the ProTaper (5.47 min), D-RaCe (4.69 min) and R -Endo (4.48 min) systems (P < 0.05). Conclusion: All retreatment rotary systems produced similarly clean canals, but the Mtwo Retreatment system was faster. Keywords: gutta-percha, NiTi instruments, retreatment, root canal preparation

Aim: To evaluate potential tooth colour alteration effect of five root canal sealers using a bovine tooth model and the interaction of formaldehyde with bismuth compounds. Materials and methods: A preliminary test was performed to assess the interaction of bismuth oxide in contact with formaldehyde. Seventy bovine teeth were sectioned into blocks and cavities were created. Each cavity was filled with either: AH Plus, Acroseal, MTA Fillapex, Sealer 26, Endofill and then sealed with composite. Triple antibiotic paste and unfilled samples were used as the positive and negative controls, respectively. All the specimens were immersed in water. The colour was assessed with a spectrophotometer at different intervals: immediately after filling, 24 h, 15 days and 30 days after filling. The colour change and the luminosity were calculated. The statistical analysis was performed using non-parametric Kruskal-Wallis and Dunn test (P < 0.05). Results: The bismuth oxide in contact with formaldehyde exhibited a black colour. All the sealers caused tooth colour alteration after the evaluated periods, with grey staining and low luminosity values observed with Sealer 26 samples. Conclusions: All the evaluated sealers caused tooth colour alteration. The tooth staining was visually detected for Sealer 26 and might be associated with the formaldehyde released and its interaction with the radiopacifier bismuth oxide. Keywords: discolouration, formaldehyde, root canal sealers, spectrophotometer, tooth staining

Aim: The aim of this survey was to assess US dentists' practice for sterilising or disinfecting new endodontic files and gutta-percha. Materials and methods: A random sample of general dentists and endodontists from all 50 US states were contacted either by email (Survey Monkey) or by post, and asked to complete a questionnaire on sterilisation and disinfection practices for new endodontic files and gutta-percha. Results: A total of 105 questionnaires were returned, with a response rate of 4.2% and 25% for email and post, respectively. Sixty-one percent of endodontists and 56% of general dentists answered 'yes' or 'sometimes' to the query regarding sterilisation of new endodontic files prior to use. The difference in the responses of specialists and general dentists was not statistically significant, despite the fact that general dentists were statistically more likely to answer that they were 'very' or 'somewhat' concerned about the effects of sterilisation on the structural integrity of endodontic files. Half of the general dentists responded 'yes' or 'sometimes' to disinfection of new gutta-percha cones, with endodontists (59%) statistically more likely to do so than general dentists (32%). Equal percentages (84% each) of endodontists and general dentists responded that they place endodontic files and gutta-percha on a sterile work surface in the dental operatory. Conclusions: The results indicate that a majority of the respondents use endodontic files and/or gutta-percha straight out of the manufacturers' packaging. There is a need to reinforce education about existing recommendations and rationale for sterilisation/disinfection of endodontic instruments and materials before use as part of the infection control process. Keywords: disinfection, endodontic files, gutta-percha, sterilisation, survey

Intrusive luxation of a permanent tooth causes extensive damage to the surrounding bone and soft tissues, in addition to resulting in a high incidence of pulpal necrosis and the potential for root resorption. When coupled with additional challenges, such as immature apical root development and a lateral luxation, thorough treatment planning and timing of treatment choices are imperative to retain the tooth in symptom-free function. This case report addresses these clinical challenges that are highlighted in a 7-year-old female patient. Keywords: intrusion, lateral luxation, orthodontics, pulpal necrosis, resorption

Aim: Evaluation of the push-out bond strength of bioceramic root canal sealer (EndoSequence BC) in comparison to a resin-based (AH Plus) sealer and a zinc oxide-eugenol-based (Kerr EWT) sealer. Materials and methods: Sixty-three roots were randomly divided into three groups (n = 21) according to the root canal sealer: group 1, EndoSequence BC; group 2, AH Plus; and group 3, Kerr EWT. Two millimetre-thick horizontal sections from the coronal, middle, and apical thirds of each root were sliced for the push-out bond strength measurement using a universal testing machine after 7, 14 and 30 days. Modes of failure were evaluated using a scanning electron microscope. Statistical analysis was performed using Kruskal-Wallis test and Mann-Whitney U test (P ≤ 0.05). Results: The EndoSequence BC samples showed the highest mean push-out bond strength values after 1 and 4 weeks, followed by AH Plus and Kerr EWT. After 2 weeks, the AH Plus samples showed the highest mean push-out bond strength values followed by EndoSequence BC. Statistically, there was a greater significant difference between the push-out bond strength mean values of the three sealers at each time interval (P < 0.001). Conclusion: The time after obturation and the basic composition of the sealer are important factors in determining the bond strength of the sealer to the root canal wall. Keywords: bioceramic, resin-based, zinc oxide-eugenol-based root canal sealer