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This article describes the diagnosis and treatment of a case of extensive apical external root resorption in the presence of a large periradicular lesion. The diagnosis was made in retrospect because the result of the resorption mimicked an immature root. The treatment consisted of the use of calcium hydroxide to induce apexification. Healing was obtained after 24 months.
In this study, the effects of pulsed Nd:YAG laser irradiation on the apical seat and periapical region of instrumented root canals were investigated. One hundred and ninety-two teeth, including incisors and molars (239 root canals), in 18 healthy adult beagle dogs were used. After extirpation of the pulp under anaesthesia, each root canal was shaped up to at least a size 40 K-file, and then laser irradiated using the following parameters: 1 W, 15 pps for 2, 3, and 4 s; 2 W, 15 pps for 2 s. The effectiveness of debris removal and carbonization on the root canal walls immediately laser irradiation were examined and inflammation of the periapical region at 1, 2, and 4 weeks after laser irradiation was examined using light microscopy. Effective debris removal was observed in most cases in the laser-treated groups and was dependent on irradiated energy. Carbonization was observed in the irradiated root canals except at the parameter of 1 W for 2 s. Periapical inflammation was observed at 1 W for 2 s to the same extent as in the control group (P > 0.01). These results suggest that the pulsed Nd:YAG laser is useful for debris removal with no adverse effects immediately after extirpation of the pulp if appropriate parameters are selected.
The results of an in vivo histological study involving apical and periapical tissues following root canal therapy after different observation periods demonstrated the most favourable histological conditions when the instrumentation and obturation remained at or short of the apical constriction. This was the case in the presence of vital or necrotic pulps, also when bacteria had penetrated the foramen and were present in the periapical tissues. When the sealer and/or the gutta-percha was extruded into the periapical tissue, the lateral canals and the apical ramifications, there was always a severe inflammatory reaction including a foreign body reaction despite a clinical absence of pain.
AIM: The aim of this study was to investigate the effect of surface morphology of root ends resected with various bur configurations on fibroblast attachment. METHODOLOGY: Seventy-two human single-rooted teeth were collected and decoronated. The root canals were instrumented, and then obturated with thermoplasticized gutta-percha using AH-26 as the sealer. The roots were randomly divided into eight different groups, and apical root-end resections were performed using eight different instruments, which included high and low speed burs and a scalpel blade. After each root was resected, the surface area of the root end was measured. Cultured human periodontal ligament fibroblasts were radiolabelled and then allowed to attach, in vitro, to the root-ends. Cell attachment to the resected root-ends was determined by counting in a liquid scintillation system and expressed as the number of decays per min/mm2 (DPM/mm2) of root surface. RESULTS: There was no significant difference in fibroblast attachment to the root-ends prepared with various instruments. CONCLUSIONS: These findings indicate that the choice of instrument for root-end resection has little influence on the initial attachment of fibroblasts, and thus may have little effect on healing following root-end resection.
AIM: The aim of this study was to evaluate the effects that various commonly used instruments have on root surface morphology, the obturating material, and the interface between the obturation and the root canal walls following root-end resection in vitro. METHODOLOGY: Sixty human single-rooted teeth with fully formed apices were collected and decoronated. The root canals were instrumented, and then obturated with thermoplasticized gutta-percha using AH-26 as the sealer. The roots were randomly divided into 12 different groups, and apical root-end resections were performed using eight different instrument configurations, and two different directions in which the bur moved across the root face in relation to its direction of rotation. Epoxy resin replicas of the resected root ends were examined using scanning electron microscopy. RESULTS: Each instrument produced a characteristic surface finish on the resected root end that mirrored its cutting profile. Irrespective of the design of the bur used, smearing and shredding of the gutta-percha across the root face occurred only when the handpiece was moved across the root face in reverse direction in relation to the direction of rotation of the bur. CONCLUSIONS: To ensure minimal disruption and distortion of the root filling and to prevent shredding of the gutta-percha interface, care should be taken to ensure that the final pass of the bur across the root canal is in the correct direction in relation to its direction of rotation.
AIM: The purpose of this study was to evaluate the sealing ability of two contemporary endodontic obturation and restorative techniques and materials. METHODOLOGY: Seventy-nine extracted human single-rooted teeth were distributed randomly in two experimental groups of 36 and 37 specimens (groups 1 and 2, respectively), one group of three positive controls and one of three negative controls. The teeth were radiographed preoperatively, accessed, and instrumented. After smear layer removal, the teeth in group 1 were obturated using the System B and Obtura and were restored coronally with Core Paste using Tenure as a bonding agent. The teeth in group 2 were obturated using the Microseal technique and were restored coronally with amalgam using Panavia 21 as a bonding agent. All teeth in groups 1 and 2 were coated with three layers of nail varnish on all of their surfaces apart from the apical 4.0 mm and the coronal area above the cemento-enamel junction. The positive control teeth were obturated, restored coronally and completely coated with varnish, whereas the negative control teeth were not obturated, restored coronally, nor coated with varnish. The teeth were radiographed postoperatively and retained in saline solution for 10 days. For the next 10 days they were submerged in India ink. Subsequently all teeth were demineralized, dehydrated and rendered transparent. Dye penetration was measured using a stereomicroscope. RESULTS: All materials and techniques provided minimal to zero dye penetration, apart from one specimen in the Core Paste group that showed 4.0 mm of dye penetration. The Wilcoxon rank sum test and t-test showed no statistically significant differences and all materials and techniques tested presented with a high degree of acceptability. CONCLUSIONS: It was concluded that these contemporary techniques and materials provide equally good results, but long-term studies are needed for outright inferences to be drawn relative to their clinical performance.
AIM: The aim of this investigation was to study the root canal anatomy of maxillary first and second molar teeth from an Irish population sample using a clearing technique. METHODOLOGY: Eighty-three extracted permanent maxillary right first molars and 40 permanent right maxillary second molars were included in this investigation. The specimens were demineralized and then cleared using methyl salicylate. The following observations were made: number of roots, prevalence of fusion, types of root canals using Vertucci's classification, presence and position of lateral canals, presence and position of transverse anastomoses, number and position of apical foramina and the frequency of occurrence of apical deltas. RESULTS: Eleven per cent of maxillary first molars and 43% of maxillary second molars had fused roots. A total of 78% of mesiobuccal roots in maxillary first and 58% in maxillary second molars had two canals. Sixty-two per cent of maxillary first and 50% of maxillary second molars had two apical foramina. There was a significant inverse relationship between age and the occurrence of two canals and between age and the occurrence of transverse anastomoses in both tooth morphotypes (P < or = 0.05). CONCLUSIONS: It is concluded that a significant proportion of the first and second molar specimens studied had two canals in the mesiobuccal root (78% and 58%, respectively) and that the occurrence of two canals and transverse anastomoses decreased significantly with increasing age.
AIM: The aim of this investigation was to assess canal cleaning following shaping with hand files of greater taper. METHODOLOGY: Thirty mesial canals and 30 distal canals in mandibular molars were prepared with .08 and .10 hand files of greater taper, respectively. Following initial preparation, 0.02 instruments were used incrementally shorter in a stepback manner. In half the canals instrumentation was performed to size 35 1 mm short of the canal terminus. In the other half the series was continued through to size 60 using stepback increments of half to one millimetre as appropriate (foramen size was maintained at size 20 in all groups). Sodium hypochlorite (4.5%) and REDTA (17%) were used as irrigants for all groups. Cleaning efficacy was evaluated by scoring the amount of remaining debris using a light microscope (x50) and calibrated eyepiece micrometer (range 0-3). RESULTS: Canals stepped back through to a size 60 were significantly cleaner than those instrumented to a size 35 only (Mann-Whitney P < 0.05). CONCLUSION: Refining the apical region of canal preparation by stepping back through to a size 60 reduced remaining debris following shaping with files of greater taper.
AIM: This study evaluated the removal of smear layer at the apical stop by pulsed Nd:YAG laser irradiation with or without black ink, and the degree of apical leakage after obturation in vitro. METHODOLOGY: Sixty extracted human single-rooted teeth were used in this study. The teeth were instrumented up to a size 40 K-file, and then divided into three groups of 20 teeth each: group 1 was unlased as a control group; group 2 was treated with a laser; group 3 was treated with a laser and black ink. The laser was operated at 2 W and 20 pp for 2 s, and irradiation was performed twice with a 30-s interval. In each group, 10 teeth for the leakage study were obturated and immersed in rhodamine B solution for 48 h at 37 degrees C, and the others were used for evaluation of remaining smear layer. All teeth were bisected longitudinally and observed by stereoscopy or scanning electron microscopy. RESULTS: The smear layer in the laser-treated groups almost melted or evaporated, and was removed significantly compared with the control group (P < 0.05). Leakage was observed in 60% of samples in group 1 and in 20% of samples in group 2. No leakage was observed in group 3, which was significantly different from the control (P < 0.05). CONCLUSIONS: These results suggest that pulsed Nd:YAG laser irradiation with black ink increases the removal of smear layer compared with that without black ink, and reduces apical leakage after obturation significantly.
AIM: The aim of this study was to compare the efficacy of root canal preparation using two automated rotary nickel-titanium instrumentation techniques with a double flared balanced forces hand preparation technique, using stainless steel files in extracted human teeth. METHODOLOGY: Sixty root canals in extracted human teeth were matched for curvature, length and diameter and divided evenly between three groups (group 1 = double flare using Flexofiles, group 2 = rotary nickel-titanium using McXIM instruments and group 3 = rotary nickel-titanium using Profile .04 Taper Series 29 instruments). The instruments were used according to the manufacturer's instructions in a torque controlled motor and handpiece (groups 2 and 3) and according to a predetermined procedure in group 1. A standardized radiographic technique using mercury as a contrast medium was used to evaluate the canal shape before and after preparation in the plane of maximum curvature. The pre- and postoperative radiographic images were compared against each other and with a predicted 'ideal preparation' calculated from a projection of the final instrument dimensions. The outcome measures were changes in canal dimensions as quantified by measuring the changes in the position of the inner and outer wall at 1 mm intervals. Alteration in canal curvature could be inferred by comparison with the ideal preparation. RESULTS: The degree of canal curvature did not influence the effectiveness of any of the techniques. The results showed no statistically significant differences in the outcome measures between the groups (two-way ANOVA). There were no significant differences in canal wall position changes at any level except the apical three, where significantly less change occurred in all groups (P = 1%). Instruments fractured in three canals, with acute curves in groups 2 and 3. CONCLUSIONS: Canal curvatures were equally and well maintained following preparation in all the groups, as long as the instrument did not fracture.
AIM: To assess the reliability of routine single radiographs in the diagnosis of inflammatory apical root resorption by correlating the radiographic and histological findings. METHODOLOGY: The material comprised serial and step serial sections of plastic-embedded root-apices with attached apical periodontitis lesions that were prepared for a previous study and the diagnostic radiographs. The histological sections of 114 specimens were analysed by light microscopy and categorized into three groups: (i) those without any resorption (0); (ii) those with moderate resorption (+); and (iii) those with severe resorption (+ +). The radiographs were examined by a separate examiner and graded with a similar categorization of no resorption (0); moderate (+); and severe (+ +) apical resorption. RESULTS: Radiographically, 19% of the teeth were diagnosed as having apical inflammatory root resorption, whereas histologically, 81% of the teeth revealed apical inflammatory root resorption. A correlative radiographic and histological assessment (n = 104) revealed a coincidence of diagnosis in 7% of the specimens and noncoincidence of diagnosis in 76% of the specimens. CONCLUSIONS: The results indicate that routine single radiographs are not sufficiently accurate or sensitive to consistently diagnose apical root resorptive defects developing as a consequence of apical periodontitis.
AIM: To describe the role of calcium hydroxide in infection control during complex endodontic retreatment. SUMMARY: A case is presented in which two conventional endodontic treatments and two surgical interventions failed to bring periapical healing. Despite this history, a further conventional treatment augmented by long-term disinfection with calcium hydroxide finally delivered a successful outcome. KEY LEARNING POINTS: Periapical healing follows proper intracanal infection control. Despite repeated surgical and nonsurgical intervention, careful retreatment can often bring healing. Calcium hydroxide has long-acting antimicrobial and soft-tissue dissolving activity. It is a helpful adjunct in endodontic retreatment.
AIM: The purpose of this study was to examine the presence of bacteria on the apical root surfaces of untreated teeth associated with chronic periradicular lesions. METHODOLOGY: Twenty-seven extracted teeth with extensive carious lesions, radiolucent lesions of varying sizes and attached periradicular lesions after extraction, were selected for study. Following fixation, lesions were removed and the apical 5-mm portion of each root was sectioned. Root tips were dehydrated, sputter-coated with gold, and then examined for the occurrence of bacteria on the apical root surfaces using a scanning electron microscope. RESULTS: Bacterial cells were usually observed close to the apical foramen, but restricted to the root canal. Morphologically, these bacteria consisted of cocci and rods. A dense bacterial aggregate composed mainly of rods was observed within the root canal and surrounding the apical foramen of one specimen. Beyond the apical foramen, other bacterial morphological types were recognized, including coaggregations of cocci and filaments, characterizing a fully developed 'corn cob'. CONCLUSIONS: Extraradicular bacteria were observed in one tooth out of 27 (4% of the cases).
AIM: The purpose of this study was to compare the efficacy in vitro of gutta-percha removal from obturated root canals using ProFiles. METHODOLOGY: Forty-eight human root canals with curvatures ranging between 25 and 45 degrees were instrumented by a standardized method to an apical ISO size 30 and 0.04 taper. They were obturated with vertically condensed gutta-percha. Retreatment was performed with the following techniques: K-Flexofiles with chloroform; Hedstrom files with chloroform; ProFiles 0.04 taper with chloroform; ProFiles 0.04 taper alone. The time for each method was measured. A microfocal macroradiographic technique was used to evaluate the amount of debris remaining within the root canals after the retreatment procedure. Roots were divided into apical, middle and coronal parts and scored on a scale of 0 (no debris) to 3 (> 50% of walls covered with debris) by trained observers on two separate occasions. RESULTS: The scores for debris remaining within root canals for K-Flexofiles with chloroform and ProFiles with chloroform were the lowest and not significantly different at all three levels of the roots examined (P > 0.05), and Hedstrom files with chloroform and ProFiles with chloroform were not significantly different in the apical part. In general, coronal parts were cleaner than apical parts. The difference in scores at the three levels between ProFiles with chloroform and ProFiles alone were each significant (P < 0.01). Instrumentation using ProFiles with chloroform (mean 6.42 min) was significantly faster than using hand files (mean 11.67 min) (P < 0.01). CONCLUSION: The results indicated that ProFiles or hand files with chloroform produced similarly clean canals, but that ProFiles were faster.
AIM: To describe the preparation of Large Root canals with small apical diameters by the GT file technique. SUMMARY: Large Root canals with small apical diameters can usually be prepared with one to three GT files; one to nine clinical steps, and one to five minutes of clinical time. Following proper access, pulp tissue should be removed, and lubricant applied to prevent pulp compaction and blockage. Initial crown-down enlargement is accomplished with up to three standard GT rotary files 0.10, 0.08 and 0.06 taper, running at 300 r.p.m., and with light touch. Care should be taken not to overload instruments, and they should be withdrawn, cleaned and inspected whenever they bind. Sometimes, the shaping objective is achieved with a single instrument; often waves of instrumentation are required before the shaping objective file cuts to length. Prior to cone-fit, the apical resistance form is confirmed with conventional files, employed as feeler gauges of the tapering form created at the canal terminus. Regardless of the shaping time, canals should be soaked with sodium hypochlorite solution for at least 30 min for effective cleaning. KEY LEARNING POINTS: Large Root canals with small apical diameters should be prepared to shaping objectives 0.08 or 0.10 taper. Compacted pulp tissue causes many canal blockages. It should be removed early, and canals should be well lubricated. Large Root canals with small apical diameters should be prepared in crown-down sequence, with recapitulation of steps until the shaping objective is achieved. Apical resistance form should always be confirmed before cone-fit. Canals should be exposed to sodium hypochlorite for at least 30 min for effective cleaning.
AIM: To describe the application of GT files in roots with abrupt curvatures. SUMMARY: Most dentists interpret obstructions to instrument progress as calcification, rather than abrupt curvature. Basically, there are not any apically calcified canals, only clinicians who are not clever enough or patient enough to sneak to patency. Dentists should be on their guard and sensitive to the 'rubber band' sensation of residual pulp tissue, and the 'loose resistance' sensation of the curved or ledged canal. Residual pulp tissue should be removed and the canal lubricated. The ledged or curved canal will only be helped by file bending. The size 10 file test is the key to identify canals requiring pre-bent instruments. The canal should first be flared short of the obstruction, before shaping the canal after it with regular, pre-bent K-files. Pre-bent GT hand-files can then be used with care to blend the apical and more coronal regions for final shape. Cone-fit may then require chilling and pre-bending GP cones (pre-bend more than one), before packing the canal. KEY LEARNING POINTS: Root canals do not calcify apically. File progress is prevented by pulp tissue, abrupt curvatures or ledging. Loose resistance to the passage of a size 10 file shows the canals that require instrument pre-bending. This test should be repeated at intervals during the preparation. Even NiTi GT files can be pre-bent for use in abrupt curves. Gutta percha cones can be pre-bent after chilling.
AIM: The purpose of this study was to compare Quantec SC rotary instruments and hand files for removal of gutta-percha during retreatment. METHODOLOGY: Twenty maxillary central incisors with a single straight canal were selected. The canals were instrumented and filled before the teeth were randomly divided into two groups of 10 specimens each. In group 1 Quantec SC rotary instruments were used for filling removal and in group 2, hand files and solvent. The following factors were evaluated: time taken to reach working length, time for gutta-percha removal, total time, apically extruded material during filling removal and number of fractured instruments. Radiographs were taken and the teeth were grooved longitudinally and split. The canal walls of each half and the radiographs were evaluated visually for cleanliness. They were then digitized using a scanner and the residual debris assessed. The analysis was carried out in the cervical, middle and apical thirds separately as well for the whole canal. RESULTS: The time for root filling removal was significantly less when Quantec SC was used (P < 0.05). The amount of apically extruded material was not significantly different between the groups (P > 0.05). Direct evaluation of the canal walls revealed that hand files and solvent demonstrated better cleanliness in the cervical third and in whole canal (P < 0.05). Radiographic analysis demonstrated that hand files performed significantly better when viewed in a mesiodistal direction (P < 0.05). CONCLUSIONS: Although Quantec SC instruments took less time, hand instruments and solvent cleaned canals more effectively.
AIM: The purpose of this scanning electron microscope (SEM) study was to compare the cleanliness of the root canal walls following either a manual or a rotary technique of canal instrumentation. The hypothesis was that a rotary technique would produce a cleaner root canal. METHODOLOGY: Manual filing was performed on 10 extracted teeth using stainless steel S-files (Sjodings, Sendoline, Sweden). Powered instrumentation was carried out on a further 10 extracted teeth, using ProFile rotary nickel-titanium files in a handpiece (250 r.p.m.) according to the manufacturer's instructions. A solution of 0.5% sodium hypochlorite was used for irrigation. The roots were cut longitudinally and the canal walls were examined for debris and smear layer at the apical, middle and coronal level. RESULTS: Significantly less debris was found in the apical region using the manual filing technique (P < 0.05); no significant differences could be found at the other levels. Overall, significantly less debris was found on the root canal walls using the manual technique when the data from the three levels were compared (P = < 0.05). CONCLUSIONS: The manual technique employed in this study produced cleaner root canal walls than the rotary ProFile technique.