Alison Qualtrough

Three-dimensional Evaluation of Effectiveness of Hand and Rotary Instrumentation for Retreatment of Canals Filled with Different Materials

The aim of this study was to measure the remaining filling volume of different obturation materials from root-filled extracted teeth by using 2 removal techniques. Eighty single-rooted teeth were collected and decoronated, and the root canal was prepared by using the ProTaper nickel-titanium rotary files. The teeth were randomly allocated into 4 groups, and each group was obturated by using a different material. Group 1 was filled with gutta-percha and TubliSeal sealer, group 2 was filled with EndoRez points and EndoRez sealer, group 3 was filled with RealSeal points and RealSeal sealer, and Group 4 was filled with a gutta-percha point and GuttaFlow sealer. Teeth were scanned with a micro-computed tomography scan, and then root fillings were removed by using ProTaper retreatment files or hand K-files. Teeth were scanned again, and volume measurements were carried out with micro-computed tomography software. Statistical analysis showed significant differences between the 2 removal techniques for gutta-percha and for both techniques between gutta-percha and the other groups. The present study showed that all tested filling materials were not completely removed during retreatment by using hand or rotary files. Gutta-percha was more efficiently removed by using hand K-files.

Evaluation of Root Canal Obturation: A Three-dimensional In Vitro Study

The aim of the study was to measure percentage of volume of voids and gaps in root canals obturated with different obturation materials by using micro-computed tomography (micro-CT). Forty-eight single-rooted teeth were collected and decoronated, and root canals were prepared by using rotary files. The roots were randomly allocated into 4 groups, and each group was obturated by using cold lateral compaction with a different material (gutta-percha and TubliSeal sealer, EndoRez points and EndoRez sealer, RealSeal points and RealSeal sealer, and a gutta-percha point and GuttaFlow sealer). Roots were scanned with micro-CT, and volume measurements for voids and gaps in the obturated roots were carried out by using specialized CT software. Percentage of gaps and voids was calculated. Statistical analysis showed that gutta-percha exhibited an overall significantly lower percentage (1.02%) of voids and gaps. The present study showed that none of the root canal filled teeth were gap-free. Roots filled with gutta-percha showed less voids and gaps than roots filled with the remaining filling materials.

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 <or= 0.05. RESULTS The overall response rate was 75%. Only 18.5% of respondents reported that they would retrieve instruments located in the apical third of root canals with a significantly higher proportion of endodontists (25.9%) compared with that of GDPs (14%) doing so. A significantly higher proportion of endodontists (98.5%) used ultrasonics for removal of fractured instruments compared with GDPs (75.8%). The most common complication of fractured instrument retrieval was thought to be excessive removal of dentine (67%). The majority of respondents (88.5%) reported that they would leave the unsuccessfully removed file in situ and obturate the root canal. CONCLUSION Both endodontists and GDPs were aware of the limitations of root canal anatomy when removal of fractured instruments was considered. Excessive removal of dentine, the most common complication associated with the removal process, suggests the need for more conservative techniques. Both endodontists and GDPs demonstrated a conservative approach when management of fractured instruments failed. Further studies regarding attitudes of GDPs and endodontists towards some specific aspects of fractured instruments management are required.

Time-dependence of coronal seal of temporary materials used in endodontics.

The aim of this in vitro study was to compare parametrically the coronal seal ability over different periods of times of four restorative materials used to seal the pulpal access cavity after endodontic treatment. One hundred and thirty-five mandibular premolars were divided randomly into three time groups (1, 2 and 4 weeks), each of which was in turn divided into four subgroups. Each subgroup was restored using one of four restorative materials: Coltosol, glass ionomer cement (GIC), zinc phosphate (ZP) cement, or intermediate restorative material (IRM) cement. The root canals were prepared using the crown-down technique, and obturated using lateral condensation. Following placement of the restorative material, the samples were incubated in distilled water at 37 degrees C and were subjected to 50 thermocycles (0 +/- 4, 56 +/- 4C). After immersing in (2%) methylene blue dye for 24 h, teeth were longitudinally sectioned and examined under a stereomicroscope. The results showed that Coltosol and GIC cement were significantly superior in sealing ability to ZP and IRM cements (P < 0.05). There was no significant difference between GIC cement and Coltosol. Both Coltosol and GIC after 1 week were significantly better than 4 weeks. There was no significant difference in the seal ability at different time periods when ZP and IRM cements were used.

A microcomputed tomography scanning study of root canal space: changes after the ultrasonic removal of fractured files.

This in vitro study aimed to investigate the effect of ultrasonic removal of endodontic fractured files on tooth structure. Fifty-three canine roots were cleaned and weighed. They were scanned by a microcomputed tomography scanner producing two-dimensional images that were reconstructed into two-dimensional slices, and, finally, the canal volume was measured. In a control group, canals were prepared to F5-size ProTaper (Dentsply Ltd, Surrey, UK). In three experimental groups, F5-fractured files were ultrasonically removed from three root canal locations: coronal, middle, and apical. All roots were reweighed and rescanned. Reconstruction and analysis were performed to remeasure the canal volume. The differences in root mass (weight) and canal volume between before and after treatment were calculated. The highest change increase in canal volume was found when fractured files were removed from the apical part followed by middle and coronal. A positive correlation existed between canal volume and root mass changes. Microcomputed tomography scanning can reliably determine changes in canal volume resulting from fractured-file removal.

The use of outreach clinics for teaching undergraduate restorative dentistry.

Aim: To examine the experience of being an outreach teacher of undergraduate restorative dentistry; to describe the desirable characteristics of such teachers; and to consider the management of outreach teaching. Design: A three year pilot of an outreach course in fourth year restorative dentistry began in 2001. Students spent one day per week treating adults in NHS community dental clinics, run by Primary Care Trusts (PCTs). Action research involved monitoring meetings with students, clinic staff (dental teachers and nurses), and PCT clinical service managers. These data are supplemented by an independent evaluation involving interviews with dental school academic staff, and an account by an outreach teacher. Results: Outreach is a different and more demanding context for teaching restorative dentistry than the dental hospital, characterised by isolation, management responsibility, pressure, a steep learning curve, and stress. The desirable characteristics of outreach teachers are those which enable them to cope in this environment, together with a student-centred teaching style, and the appropriate knowledge. Management of teaching passed to the PCTs and this created an additional workload for them in relation to staffing, risk, and service-based issues. Four teaching surgeries were the maximum for a satisfactory level of patient care and student supervision. A key issue for the dental school is quality. The changes to teaching and the teaching environment introduced during and after the pilot to address problems identified are described. Conclusion: In developing facilities to enable students to benefit from the advantages of outreach, dental schools should recognise that the characteristics of the outreach environment need to be taken into account during planning, that staff selection is a critical success factor, and that an ongoing proactive approach to organisational arrangements and to the support of teaching staff is necessary.

The failure rate of NHS funded molar endodontic treatment delivered in general dental practice

Objective To describe the quality and record the outcomes of root canal therapy on mandibular, first permanent molar teeth provided by GDPs working according to NHS contracts.Design Descriptive, retrospective cohort study.Setting Twelve general dental practices in Salford, North West England.Subjects and method All patients aged 20-60 years attending the practices who had received a NHS-funded root filling in a mandibular first permanent molar between January 1998 and December 2003. The radiographic quality of root fillings in the teeth was assessed by an endodontic specialist and categorised into optimal, suboptimal and teeth which had no radiograph, or an unreadable radiograph. Teeth were also dichotomised into those restored with a crown and those restored with an intracoronal restoration. Failure as an outcome was defined as if a tooth was extracted, the root filling was replaced or periradicular surgery was performed on the tooth. Crude failure rates per 100 years were calculated for optimally, sub-optimally root filled teeth and for those with no or an unreadable radiograph, and according to how the tooth was coronally restored. Survival was assessed using Kaplan-Meier curves and Cox proportional hazards were used to determine factors linked with increased failures.Results One hundred and seventy-four teeth were included in the study, of which 16 failed. The crude failure rates per 100 years with a root filled tooth were very low and differed little (p = 0.9699) for optimally (2.6), sub-optimally (2.5) root filled teeth and for those with no or an unreadable radiograph (2.9), with approximately one in 37 root filled mandibular first molar teeth failing each year. The majority of root fillings fail within the first two years (N = 10, 62.5%). Some 67 teeth (38.5%) were restored with a crown, none of which failed during the follow up period compared to those with a plastic restoration (p = 0.0004).Conclusions The very low failure rates have significant implications for the design of research studies investigating outcomes of endodontic therapy. The similar failure rates for teeth that had optimal and suboptimal root fillings suggest that endodontic treatment is not as technique sensitive as previously thought. The results also support the notion that the coronal restoration is more important than radiographic appearance of the root filling.

Factors Affecting Temperature Rise on the External Root Surface During Ultrasonic Retrieval of Intracanal Separated Files

Temperature rise (TR) on the external root surface during ultrasonic removal of separated files (SFs) from 50 lower incisors roots of 10-mm length was investigated. CPR ultrasonic tips (Obtura-Spartan, Fenton, MO) were used dry to retrieve F2 ProTaper (Dentsply, Surrey, UK) segments fractured 2.5 mm from the coronal access in five groups: CPR2, CPR5, and CPR6 at power setting 1 and CPR5 at power settings 2.5 and 5. Temperature changes were inspected at 30-second intervals up to 120 seconds at three different sites: two at mesiodistal and buccolingual surfaces adjacent to the most coronal aspect of the SF and the third adjacent to the most apical aspect. Overall, the highest mean TR was at the buccolingual root surface followed by that at the mesiodistal and the more apical site surfaces. At power setting 1, CPR6 produced a significantly lower TR than CPR5, and both can be used for 120 and 60 seconds, respectively. Power setting 5 is not recommended for the removal of SF because this induces a hazardous TR.

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.

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.