Magnification in undergraduate endodontic teaching in the UK and Ireland: a survey of teaching leads in Endodontology.

AIM: To investigate the use of magnification in undergraduate endodontic teaching in dental schools within the UK and Ireland and identify factors that may impact on levels of adoption. METHODOLOGY: An electronic questionnaire was distributed to teaching leads in undergraduate endodontics in all UK and Ireland dental schools. RESULTS: Completed questionnaires were received from 15 of 18 course leads. The study revealed magnification is not universally embedded within the undergraduate curricula, and the majority of schools had no expectation for students to use magnification, although it was encouraged. The study provided insight into teaching staff factors, student factors and institutional factors that impact upon the adoption of magnification in undergraduate endodontic teaching. Although course leads utilized magnification in their own practice, this did not translate into institutional expectation for students to use magnification. Barriers to adoption of such an institutional expectation included cost and lack of staff training. CONCLUSIONS: Magnification has become viewed as an essential part of endodontic practice. The dental operating microscope has the most significant impact on endodontic visualization; however, the use of dental loupes in nonsurgical endodontics could be considered the minimum standard. The pedagogical dilemma faced by dental educators training undergraduates to behave in a manner that they themselves would not, cannot be rationalized on the basis of cost and lack of staff training. It is proposed that although significant, these barriers are not insurmountable and the use of dental loupe should become an expectation in undergraduate training in the UK and Ireland.

Pulp sensibility and vitality tests for diagnosing pulpal health in permanent teeth: a critical review.

The aim of this review was to critically appraise the literature related to pulp vitality and sensibility testing in order to determine the diagnostic accuracy of pulp tests with reference to a gold standard or control group. Implications of the results for research and clinical practice are also explored. The MEDLINE (Ovid), MEDLINE (PubMed), Embase and Cochrane databases were searched for English-language clinical trials in humans in which in vivo studies were designed to evaluate or compare the accuracy of selected pulp sensibility and pulp vitality tests in determining the state of pulpal health in permanent teeth. Studies were included only if the results were compared to a control group or to a valid gold or reference standard. Eight studies were identified. Shortcomings in research design were found to influence the findings. The limited number of studies investigating pulp vitality tests was insufficient to answer the research question. It was concluded from this critical appraisal of the literature that laser Doppler flowmetry appeared to be the most accurate method for diagnosing the state of pulpal health and came closest to serving as a gold standard. Pulp vitality tests proved superior to pulp sensibility tests for early and accurate assessments of the pulpal health of traumatized teeth. When accurately used and interpreted, pulp sensibility tests provide valuable diagnostic information, particularly when an electric pulp test is used in combination with either CO2 snow or Endo-Ice.

Rethinking root canal treatment: understanding the difference between preventing and treating endodontic infection.

Root canal treatment is a frequently performed procedure aimed to address pulpal and peri-radicular disease. It comprises a number of clinical steps regardless of the initial diagnosis. The emphasis of each step varies according to whether there is a vital pulp (non-infected) or if the pulp system contains necrotic, infected tissue and there is peri-apical pathology. This article aims to discuss the differences in performing root canal treatments on teeth with vital and non-vital pulps. The reader should understand the differences between performing a root canal treatment in teeth with vital pulps and those with infected root canal spaces and peri-radicular pathology.

Undergraduate endodontic education: what are the challenges?

To deliver the knowledge and skills required to equip undergraduate students for practice is a significant responsibility; graduates must be familiar with the diagnosis and treatment of pulpal and periradicular diseases and the preservation and restoration of pulpally compromised teeth. A greater understanding of the microbiological processes involved in endodontics and developments in instruments and materials have transformed our approaches to root canal treatment. Information technology has revolutionised certain aspects of education and has had an effect on endodontic teaching. Dental graduates will be expected to treat an increasingly elderly population and will enter a climate in which remuneration for root canal treatment could have a significant effect on the number of cases treated and the pattern of referral. Teachers of endodontics at the majority of dental schools are taxed by competing demands for time in packed curricula, a lack of availability of natural teeth for classroom exercise and a lack of suitable patients. The debate as to whether endodontics should be a specialist subject in its own right has rumbled on for three decades. Compared with the situation in the 1970s, there are now well defined curricula guidelines to which those involved in teaching can refer and map teaching in their schools against agreed norms. These create the potential for students to graduate with the knowledge and skills at a sound level of competence to carry out endodontic procedures and with a deeply engrained understanding of the need for continuing professional development.

Effect of retained fractured instruments on tooth resistance to vertical fracture with or without attempt at removal.

AIMS: To investigate the effect of retained fractured endodontic instruments on root strength and to evaluate the effectiveness of several root filling materials in reinforcing roots that had undergone unsuccessful attempt at removal of fractured instruments. METHODOLOGY: Seventy five mandibular premolar roots were divided into five groups. In group A (control), canals were prepared to a size F5-ProTaper instrument and filled with gutta-percha and TubliSeal sealer fragments. In the experimental groups (B, C, D and E), 4 mm of F5-ProTaper instruments were fractured in the apical one-third of the canal and then treated as follows: in group B, the fragments were left in situ without attempt at removal, and canals were filled with gutta-percha and TubliSeal sealer (GP No Removal). In groups C, D and E, an attempt at removal of the fragment was simulated by preparing a staging platform coronal to the fragment using modified Gates Glidden burs (No 2-5). Canals in group C were filled with gutta-percha and TubliSeal sealer (GP Removal), group D filled with Resilon (Resilon Removal) and group E with mineral trioxide aggregate (MTA Removal). Roots then underwent vertical fracture. Data were analysed using the one-way anova at P<0.05. RESULTS: Roots in the GP Removal group had significantly lower values for mean force for fracture (404.9 N). There was no significant difference between the control group and GP No Removal (765.2 and 707.8, respectively). Resilon Removal and MTA Removal groups (577.3 and 566.6 N) were not significantly different from the GP No Removal group. CONCLUSIONS: Leaving fractured instruments in the apical one-third of the canal does not appear to affect the resistance of the root to vertical fracture; Resilon and MTA appear to compensate for root dentine loss that occurred as a consequence of attempts at retrieval of fractured instruments when used as canal filling materials.

The impact of different viewing conditions on radiological file and working length measurement.

AIM: To determine the effect of different viewing conditions and observer experience upon the accuracy of file and working length measurements using analogue intra-oral radiographs. METHODOLOGY: Twenty-five observers from a range of clinical backgrounds examined working length analogue periapical radiographs of 30 extracted teeth. Each participant measured both file (FL) and working length (WL) on each of the radiographs using three different viewing conditions consisting of a viewing box, a viewing box with film masking and a viewing box with film masking and x2 magnification. Statistical analysis was conducted to derive interobserver reliability by intraclass correlation coefficients, and multiple linear regression models were fitted to compare the mean differences between the joint consensus between specialists and estimated values for file length and working length for each of the three viewing conditions. RESULTS: Multiple regressions models were fitted and found significant differences between the use of the viewing box alone and a viewing box with masking (FL P = 0.001; WL P < 0.001) and the use of the viewing box alone and with a viewing box employing masking and magnification (FL P < 0.001; WL P = 0.002). Intraclass correlation coefficient showed a high level of agreement between all observers; however, no statistically significant differences were found between the five observers groups for either mean file length or working length values. CONCLUSIONS: The results of this study are in agreement with National and European guidelines, which recommend the use of a viewing box, magnification and masking for radiographic interpretation.

Vertical fracture resistance of roots after ultrasonic removal of fractured instruments.

AIMS: To investigate ex vivo root resistance to vertical fracture after fractured instruments were ultrasonically removed from different locations in the root canal. MATERIALS AND METHODS: Fifty-three canine roots were weighed and divided into four groups. Eight roots served as a control group in which canals were instrumented to a size F5-ProTaper instrument. In the experimental groups, F5-ProTaper fragments were fractured in the coronal, middle and apical one-thirds, and then removed ultrasonically. The time required for removal was recorded. Roots were reweighed, and canals were shaped to a size F5-ProTaper and filled with GuttaFlow. After incubation, roots underwent a vertical fracture test in which the force at fracture was recorded. The difference in root mass before and after treatment (fractured file removal or canal preparation) was calculated. Data were analysed using the Kruskal-Wallis, Mann-Whitney post-hoc and regression tests at P < 0.05. RESULTS: The highest root-mass loss was recorded when fragments were removed from the apical one-third (46.04 mg) followed by the middle and coronal (27.7 and 13.5 mg, respectively); these differences were significant (P < 0.05). There were significant differences in the force required for vertical fracture amongst the experimental groups (P < 0.05) with the lowest mean force recorded in the apical-third group (107.1 N) followed by the middle and coronal (152.6 and 283.3 N, respectively). The highest mean force was recorded in the control group (301.5 N) which was not significantly different from that in the coronal group (P = 1.00). A negative exponential correlation (r = 0.669) existed between the root-mass loss and the force required to fracture the roots. CONCLUSION: Whilst removal of fractured instruments from the coronal one-third of the root canal can be considered as a safe procedure, removal from deeper locations renders the root less resistant to vertical fracture.

Endodontists experience using ultrasonics for removal of intra-canal fractured instruments.

AIM: To investigate the experience of UK endodontists with aspects of ultrasonic use for removal of intra-canal fractured instruments. METHODOLOGY: A questionnaire form comprising both close-ended and partially close-ended questions with a covering letter explaining the aims of the study and indicating that all information would remain confidential and anonymous were sent to 180 endodontists working in the UK. Non respondents received a reminder with a differently worded covering letter. After collecting the responses, data were entered into SPSS software through which frequencies were determined and the chi-square test at the 0.05 level of significance, when required, was applied. RESULTS: Overall, 97% of endodontists reported the use of ultrasonics for removal of fractured instruments. The majority of them (78%) used ultrasonics with a coolant at least some of the time. Forty-seven per cent of users activated tips at medium to maximum power settings. The greatest proportion (53%) activated the tips for approximately 10 s. CONCLUSIONS: Endodontists reported different techniques when using ultrasonics for removal of fractured instruments.

The influence of coronal tooth tissue in the diagnosis of apical pathosis.

AIM: To assess the influence of the status of the crown of the tooth on the observers' periapical radiological assessment. METHODOLOGY: Seven clinical tutors, eight postgraduate students and seven undergraduate students were recruited. Each evaluated 24 periapical radiographs comprising 12 radiographs with teeth restored with small to medium coronal restorations and 12 radiographs displaying teeth which were either heavily restored or exhibited gross caries. Two viewing sessions, separated by several weeks, were undertaken using ideal viewing conditions. In the first viewing teeth were examined in their entirety and in the second the coronal aspects of the teeth were obscured. RESULTS: An analysis of variance found no significant differences between the groups of observers during the first viewing. When the crowns were masked, undergraduate students had a significantly lower sensitivity (P = 0.008) compared with postgraduates and clinical tutors. Paired t-tests found a significant increase in the sensitivity of the postgraduate students between the first and second viewing (P = 0.037). Mean sensitivity and specificity for the undergraduates decreased from 0.67 to 0.63 and 0.64 to 0.60 for the first and second viewing, respectively, whilst mean sensitivity for postgraduates and clinical tutors increased from 0.59 to 0.79 and 0.69 to 0.80, respectively. Specificity increased from 0.72 to 0.78 for the postgraduates between viewings, whilst the tutors recorded 0.80 for each viewing. CONCLUSION: The status of coronal tooth tissue had a major impact on the diagnostic accuracy of the observers with limited radiological experience supporting the need for earlier radiological training within the undergraduate curriculum.

Opinions and attitudes of endodontists and general dental practitioners in the UK towards the intracanal fracture of endodontic instruments: part 1.

AIM: To investigate the attitudes and opinions of general dental practitioners (GDPs) and endodontists in the UK towards fracture of endodontic instruments. It was hypothesized that there would be no significant difference between GDPs and endodontists regarding their experience of fracture of endodontic instruments. METHODOLOGY: A pilot questionnaire was carried out on 20 postgraduate dental students to ensure that the questions were easily understood. This was followed by a further pilot survey on a group of GDPs and endodontists (50) to facilitate sample size calculation. The sample size comprised 330 systematically selected GDPs, and all endodontic specialists working in the UK (170). The questionnaire comprised both close-ended and partially close-ended questions in four categories: demographics; pattern of practice and experience of instrument fracture; management of fractured instruments; and unsuccessful management of fractured instruments. Nonrespondents were sent another two mailings (first and second reminders). After collecting the responses, data were analysed using chi-square and Linear-by-Linear Association tests at the 0.05 level of significance. RESULTS: The overall response rate was 75% (82.82% for endodontists and 70.92% for GDPs). Overall, 88.8% of respondents had experienced fractured instruments with a significantly higher proportion of endodontists (94.8%) compared with that of GDPs (85.1%). CONCLUSION: Both endodontists and GDPs were aware of most factors contributing to endodontic instrument fracture. With experience and knowledge, fracture of endodontic instruments was associated with the number of root canal treatments performed.

Cleaning endodontic files in a washer disinfector.

AIMS: The aim of this study was to compare the cleanliness of endodontic files that had been cleaned in a washer disinfector according to the file holding mechanism within the machine. METHODOLOGY: Selected canals of extracted teeth were filed with new, unused files. One set of files (size 15 to 40) was used for each canal. A total of 192 files were used for cleaning and shaping. The files were divided into three groups. The first group was a control group containing 30 files, which were not cleaned in the washer disinfector. The second and the third groups were the experimental groups with 81 files in each group. These files were cleaned in the washer disinfector using different holding mechanisms (file holder or cleaning basket) for each group. The files were examined for visible debris under a light microscope at x45 magnification. RESULTS: None of the 162 cleaned files were totally free of organic debris. Comparison of the debris scores in the two experimental groups showed that the files in the cleaning basket group were significantly cleaner than those in the file holder group. The files in both test groups were significantly cleaner than those in the control group. CONCLUSIONS: Endodontic files cannot be totally cleaned using a washer disinfector alone. The instrument holding mechanism within the machine has a significant effect on the cleanliness of the files after one intensive cleaning cycle.

Factors contributing to the separation of endodontic files.

Cleaning and shaping of the root canal system is essential for successful endodontic treatment. However, despite improvements in file design and metal alloy, intracanal file separation is still a problematic incident and can occur without any visible signs or permanent deformation. Only a few studies have reported high success rates of fractured file removal using contemporary techniques. Conflicting results have been reported regarding the clinical significance of retaining separated files within root canals. An understanding of the mechanisms of, factors contributing to, file fracture is necessary to reduce the incidence of file separation within root canals. This article reviews the factors that are of utmost importance and in light of these, preventive procedures and measures are suggested.

Opinions and attitudes of endodontists and general dental practitioners in the UK towards the intra-canal fracture of endodontic instruments. Part 2.

AIM: To investigate the attitudes of general dental practitioners (GDPs) and endodontists in the UK towards management of fractured endodontic instruments. METHODOLOGY: A questionnaire was sent to 330 systemically selected GDPs and all endodontists working in the UK (170). It was accompanied by a covering letter explaining the aims of the study and indicating that all the information given would remain confidential. Those who did not respond to the first mailing were sent another two mailings. Data were analysed using chi-square test at P

Comparison of an ultrasonic cleaner and a washer disinfector in the cleaning of endodontic files.

The aim of this study was to compare the amount of residual organic debris on endodontic instruments that had been cleaned in either an ultrasonic bath or a washer disinfector prior to sterilisation. A total of 90 endodontic files of varying sizes were used to clean and shape root canals in extracted teeth and were then placed in endodontic file holders. Test group 1 (36 files) were ultrasonically cleaned for 10 min and test group 2 (36 files) were cleaned in a washer disinfector. A control group (18 files) were not cleaned at all. Following sterilisation, all the files were visually inspected under a light microscope and scored using an established scale. The results showed that both test groups had significantly less residual debris than the control group. Comparing the test groups, the files that had been cleaned ultrasonically had significantly less debris than those cleaned in the washer disinfector. The design of the instrument holder may have been a factor in this result. More research is needed into the use of washer disinfectors in the cleaning of small dental instruments that have a complex surface structure.

The effect of pre-soaking and time in the ultrasonic cleaner on the cleanliness of sterilized endodontic files.

AIMS: To assess whether pre-soaking files in an enzymatic cleaner prior to ultrasonic cleaning had any effect on cleanliness and also to assess the effect of the time that endodontic files spend in an ultrasonic bath prior to sterilization on their overall cleanliness. METHODOLOGY: Twenty root canals in a total of ten patients were cleaned and shaped using conventional techniques. Following use, some of the files were pre-soaked and then ultrasonically cleaned for either 5, 10, 30 or 60 min. Other files had no pre-soaking and were then ultrasonically cleaned. There were two control groups, one where the files were pre-soaked and not ultrasonically cleaned and the other where the files were neither pre-soaked nor ultrasonically cleaned. All files were then subjected to a standard packing and autoclaving process. Following autoclaving, the files were examined using a light microscope at a magnification of 40x. The cutting section of each file was divided into two parts, the tip and the shaft, for visualization under the microscope. Any debris or cement on the files was scored using a modification of the scale used by Smith et al. (Journal of Hospital Infection, 51, 2002, 233). The data were analysed using one-way analysis of variance. RESULTS: Pre-soaking had no significant effect on the cleanliness of the files (P = 0.18 at the tip, P = 0.93 at the shaft). Ultrasonic cleaning had a significant effect on the cleanliness of the files (P < 0.00) but there was not a linear relationship between cleanliness and the ultrasonic cleaning time. There was little benefit in extending the ultrasonic cleaning time beyond 5 min. Calcium hydroxide deposits on two files were resistant to ultrasonic cleaning. CONCLUSIONS: There is no benefit in pre-soaking endodontic files prior to ultrasonic cleaning. The optimum time for ultrasonic cleaning was between 5 and 10 min. Further ultrasonic exposure, up to 60 min, did not improve cleanliness. Although a majority of files were free from debris following ultrasonic cleaning, a substantial minority still retained debris. This supports the case for endodontic files being single-use only.

A laboratory comparison of three imaging systems for image quality and radiation exposure characteristics.

AIM: To measure and compare the relationships between image quality and X-ray exposure for three types of intraoral imaging system (conventional film, phosphor plate system and CCD-based system). METHODOLOGY: Kodak 'Insight' F-speed film, Digora FMX (phosphor plate system) and Visualix USB (CCD system) were used to produce series of radiographic images of two tooth-bearing jaw specimens (maxillary molar and mandibular molar regions) at a range of X-ray exposures from 10 ms to 2000 ms (all at 6 mA and 60 kV). Digital images were viewed from a computer monitor and films viewed on a conventional light box. Five observers scored each image using a five-point subjective image quality scale (0-4). RESULTS: Optimum image quality (4) was seen for conventional film. Neither digital system achieved this score at any exposure, achieving in both cases a maximum mean score of 3.1 (adequate visualization). The two digital systems, however, provided adequate visualization at substantially lower exposure times. Dose reduction over conventional film for maximum quality images with Visualix USB was 20%, but for Digora FMX it was 70%. All three systems gave acceptable (quality score of two or higher) images over a broad range of exposures. CONCLUSIONS: In terms of subjective image quality, F-speed film performed better than the two digital systems, but this must be weighed against the ability of the two digital systems to give adequate image quality at lower radiation doses.

An in vitro comparison of pH changes in root dentine following canal dressing with calcium hydroxide points and a conventional calcium hydroxide paste.

AIM: This study aimed to measure and compare pH changes at apical and cervical sites on the external root surface of extracted teeth dressed with calcium hydroxide in two different formulations. METHODOLOGY: Root canals of 45 single-rooted extracted human teeth were accessed and shaped using a step-down technique with rotary instrumentation. Standard cavities were prepared on the external root surface at specific apical and cervical sites. The teeth were randomly allocated to three groups. Teeth in group A were dressed with calcium hydroxide points, those in group B were dressed with an aqueous calcium hydroxide paste and teeth in group C were left unfilled. Following storage in humid conditions, the pH of the dentine at apical and cervical sites was measured at baseline and then at 24 h, 72 h, 1 week, 10 days, 2 weeks and 3 weeks. RESULTS: The pH of the root dentine at both apical and cervical sites was significantly greater (P < 0.001) in teeth dressed with aqueous calcium hydroxide paste compared with those dressed with calcium hydroxide points, when averaged out across all time periods. For all groups, there was a significant difference between the mean apical and cervical pH values for each tooth with lower values for the apical sites (P < 0.001). CONCLUSION: The results of this study indicate that an aqueous calcium hydroxide paste was more effective than calcium hydroxide points at raising the pH on the external root surface of extracted teeth.

Management of tooth surface loss.

This part of the series is devoted to tooth surface loss (TSL) not caused by caries or trauma. The management of this form of generalised TSL is included in this series because knowledge of occlusion is needed for both the diagnosis and, when indicated, treatment. There are, however, many other factors involved in the management of generalised TSL other than those associated with 'occlusion'. These will also be discussed.