Itzhak Abramovitz

The Unpredictability of Seal After Post Space Preparation: A Fluid Transport Study

A root canal filling remaining after post space preparation is commonly expected to provide adequate seal. Coronal leakage of 30 endodontically treated teeth was measured before post space preparation using a fluid transport assay. In 10 of these teeth post space was prepared, using a two-step procedure, first to a remaining filling of 6 mm and then to 3 mm, with the leakage studied after each step. In 10 teeth the removal was done in one step to a remaining length of 3 mm. The other 10 teeth, with intact root canal fillings, served as controls and were tested twice for leakage. A significant difference was found between the sealing ability of intact fillings and that of partially removed ones (p < 0.05). The difference between the sealing ability of 3 and 6 mm remaining length group was not statistically significant. The lack of statistical differences between the 6 mm and 3 mm fillings was due to a great variability which existed among the 3 mm remaining fillings. These results suggest that 3 to 6 mm fillings provided a seal inferior to that of intact root canal fillings. Reduction of the fillings to 3 mm resulted in an unpredictable seal.

Correlation Between Remaining Length of Root Canal Fillings After Immediate Post Space Preparation and Coronal Leakage

The seal provided by root canal fillings after post space preparation was studied using a pressure-driven radioactive tracer assay. The coronal part of root canal fillings was immediately removed, using a hot plugger, to a remaining length of either 3, 5, 7, or 9 mm. Intact root canal fillings of 14 mm served as control. Application of air pressure of 130 mm Hg to the tracer solution drove it through the fillings and into phosphate-buffered saline surrounding the apex. Leakage gradually increased for 28 days, and differences in the leakage through 3 to 9 mm fillings were demonstrated. In a passive system by which an additional group of teeth were tested none of these differences could be detected. It was concluded that: (a) root canal fillings of 3, 5, and 7 mm have an inferior seal, compared with that of an intact filling; (b) the sealing is proportional to the length of the remaining filling; and (c) a passive system is unable to detect these differences, even when conducted for as long as 28 days.

The efficacy of five techniques for removing root filling material: microscopic versus radiographic evaluation.

AIM   To test and compare the efficacy of five methods for the removal of root filling material and to test the hypothesis that radiographs fail to represent the real extent of remaining material on canal walls. METHODOLOGY   Fifty maxillary anterior single-rooted teeth with straight root canals were selected. The coronal third of each root canal was prepared with Gates-Glidden drills to number 3, whilst the apical two-thirds were prepared with manual K-files to size 40. Root fillings were performed using lateral compaction with gutta-percha and AH-26. After full setting, the coronal third of the root filling was removed with Gates-Glidden drills and the teeth divided into five groups (n=10). The remaining root filling material was then removed with either Hedström files and chloroform (25 μL), using size 40 as the last file, SafeSider files, using a NiTi Pleezer reamer with a 0.06 taper followed by size 40 reciprocating file, with or without chloroform, or ProTaper Universal retreatment files (D2, D3) with or without chloroform. Reaching working length with no more gutta-percha on the last file was defined as the endpoint for all procedures. The presence of remaining filling material was first evaluated radiographically and then by the microscopic evaluation of split roots. The time required to accomplish the procedure was also recorded. anova and anova with repeated measures were used for statistical analysis of the results. RESULTS   Overall, 11-26% of the canal wall remained covered with filling material; no significant difference was found between the groups. The mechanized methods were faster than manual removal of filling material (P < 0.01); the use of solvent did not speed up the mechanized procedures. Radiographic evaluation failed to adequately and reliably detect the extent of filling material remaining on the canal walls, which was later observed by microscopic evaluation. CONCLUSIONS   All methods left root canal filling material on the canal walls. Radiographic evaluation failed to detect the extent of remaining root filling material, which could only be detected using microscopy.

The Effect of Immediate Vs. Delayed Post Space Preparation on the Apical Seal of a Root Canal Filling: A Study in an Increased-Sensitivity Pressure-Driven System

A 5 mm remaining length of root canal filling, after post space preparation, is commonly assumed to maintain sealing ability similar to that of the intact filling. Post spaces were prepared either immediately using hot pluggers, or later, using drills. The sealing ability of the fillings, 5 mm remaining length, were compared with each other and with an intact root canal filling control, using radioactive tracer in a pressure-driven system. When no pressure was applied, no differences could be detected between either of the groups and the control. When a pressure of 120 mm Hg was applied to the same teeth, the control group clearly maintained a better seal than each of the experimental groups, which did not significantly differ from each other. These results suggest that (a) the pressure-driven system was more sensitive than the passive leakage assay that failed to detect differences even at 14 days; (b) a remaining root canal filling of 5 mm was inferior to the intact root canal filling; and (c) the immediate post space preparation with hot pluggers did not differ from a delayed preparation with drills.

The effectiveness of a self-adjusting file to remove residual gutta-percha after retreatment with rotary files.

AIM To test the efficacy of a two-stage retreatment method in which the Self-Adjusting File (SAF) is used to remove root canal filling residue left in the canal after using ProTaper Universal retreatment files. METHOD One of the curved mesial canals of 25 extracted mandibular molars was instrumented up to ProTaper F2, followed by NiTi K-files up to size 45 and filled. Radiographs of these canals served as a pre-treatment control, which was later compared with those of the same canals after each stage of the retreatment procedure. Stage 1 consisted of ProTaper Universal D1-D3 retreatment files, which were used to remove the bulk of root filling material, followed by stage 2 in which a SAF file was applied to remove the remaining root canal filling residue. The amount of the radiopaque material in each third of the canal was evaluated before and after each stage, using bucco-lingual and mesio-distal radiographs. The amount of residue was expressed as the per cent of the root canal filled area, as measured in the pre-treatment control. The difference between the control and results of the first and second stages of retreatment was analysed using the Wilcoxon signed-rank test. RESULTS Radiopaque residue was present after the use of the ProTaper Universal rotary files in 7.8 (± 12.9)%, 12.9 (± 13.9)% and 34.7 (± 22.8)% of the coronal, mid-root and apical areas, respectively. Following the supplementary application of the SAF, the amounts of residue were reduced to 2.6 (± 3.7)%, 4.1 (± 5.7)% and 6.7 (± 9.4)% of the coronal, mid-root and apical canal areas, respectively (P < 0.01 for the coronal and mid-root and P < 0.001 for the apical third). CONCLUSION No system removed the root filling materials entirely. The use of the SAF after rotary instrumentation using ProTaper Universal retreatment files resulted in a significant reduction in the amount of filling residue in curved canals of mandibular molars.

Case selection for apical surgery: a retrospective evaluation of associated factors and rational.

Endodontic failures associated with poor quality of endodontics respond favorably to retreatment. Nevertheless, under certain clinical conditions, apicoectomy should be the preferred procedure. A retrospective survey of 200 roots that were referred for apical surgery revealed that 83% of the roots were inadequately obturated, including 8.5% with no root canal filling at all. In 49 of the roots in this group (24.5% of the referred cases) nonsurgical retreatment was judged by an endodontist as either impossible or improbable because it might jeopardize the root integrity. Retreatment should have been the preferred treatment modality for the rest of the group, provided that coronal restorations could be safely bypassed or removed. Posts were found in 63 of these teeth, however 35 of them were either short or loosely fitting and could safely be removed. The rest of the posts were longer than 5 mm, which might have presented a problem if their removal was attempted. In 45% of the 200 cases in the present study, surgical intervention was justified. The rest of the cases (55%) should have either been subjected to a follow-up (10.5%) or retreated nonsurgically by a skilled endodontist (44.5%). These results indicate that referring dentists may not appreciate the retreatment possibilities offered by modern endodontics, and they emphasize the need for a shift of concept: endodontists should be involved in the decision making before referring a patient to surgery.

Failure of treatment of impacted canines associated with invasive cervical root resorption

OBJECTIVES To propose invasive cervical root resorption (ICRR) as an unrecognized and/or overlooked etiologic factor in the failure of response of an impacted tooth to orthodontic traction and to underline the importance of cone beam computerized tomography (CBCT) for early and accurate diagnosis of ICRR. MATERIALS AND METHODS Fourteen patients (age 13-21 years) with impacted canines (15 canines) that had failed to respond to orthodontic forces and that exhibited ICRR formed the case series for this investigation. The initial diagnosis, treatment, clinical and radiographic expression of failure, and adverse effects on adjacent teeth were analyzed. RESULTS Initial diagnosis had been performed on plane radiographs. The orthodontist was absent during surgery in 11 patients. Nine canines had been exposed by open procedures. ICRR was not related to the severity of impaction. Its diagnosis was made on existing radiographs, new films, and/or new CBCT. The severity of the lesions was Class 3 or 4, and the teeth were finally extracted. Loss of anchorage characterized 11 patients. Apical resorption of the roots of adjacent teeth was diagnosed in 9 patients. CONCLUSIONS ICRR is a frequently undiagnosed or unrecognized cause of failure of orthodontic resolution of impacted canines and should be distinguished from replacement resorption. CBCT should be used for its early detection and accurate assessment of potential damage to adjacent anchor teeth.

In vitro biocompatibility of endodontic sealers incorporating antibacterial nanoparticles

The main cause of endodontic disease is bacteria. Disinfection is presently achieved by cleaning the root canal system prior to obturation. Following setting, root canal filling is devoid of any antibacterial effect. Endodontic sealers with antimicrobial properties yet biocompatible may enhance root canal therapy. For this purpose, quaternized polyethylenimine nanoparticles which are antibacterial polymers, biocompatible, nonvolatile, and stable may be used. The aim of the present study was to examine the impact of added QPEI on the cytotoxicity of AH Plus, Epiphany, and GuttaFlow endodontic sealers. The effect of these sealers on the proliferation of RAW264.7 macrophage and L-929 fibroblast cell lines and on the production of TNFa from macrophages was examined. Cell vitality was evaluated using a colorimetric XTT assay. The presence of cytokines was determined by two-site ELISA. Results show that QPEI at 1% concentration does not impair the basic properties of the examined sealers in bothmacrophages and fibroblast cell lines. Incorporation of 1% QPEI into the sealers did not impair their biocompatibility. QPEI is a potential clinical candidate to improve antibacterial activity of sealers without increasing cytotoxicity

Rapid Kill—Novel Endodontic Sealer and Enterococcus faecalis

With growing concern over bacterial resistance, the identification of new antimicrobial means is paramount. In the oral cavity microorganisms are essential to the development of periradicular diseases and are the major causative factors associated with endodontic treatment failure. As quaternary ammonium compounds have the ability to kill a wide array of bacteria through electrostatic interactions with multiple anionic targets on the bacterial surface, it is likely that they can overcome bacterial resistance. Melding these ideas, we investigated the potency of a novel endodontic sealer in limiting Enterococcus faecalis growth. We used a polyethyleneimine scaffold to synthesize nano-sized particles, optimized for incorporation into an epoxy-based endodontic sealer. The novel endodontic sealer was tested for its antimicrobial efficacy and evaluated for biocompatibility and physical eligibility. Our results show that the novel sealer foundation affixes the nanoparticles, achieving surface bactericidal properties, but at the same time impeding nanoparticle penetration into eukaryotic cells and thereby mitigating a possible toxic effect. Moreover, adequate physical properties are maintained. The nanosized quaternary amine particles interact within minutes with bacteria, triggering cell death across wide pH values. Throughout this study we demonstrate a new antibacterial perspective for endodontic sealers; a novel antibacterial, effective and safe antimicrobial means.

Antibacterial temporary restorative materials incorporating polyethyleneimine nanoparticles.

OBJECTIVES Temporary restorative materials (TRMs) often rapidly lose their dimensional stability and antibacterial properties after exposure to humidity and bacterial infection. Quaternary ammonium polyethyleneimine (QPEI) nanoparticles (NP) are long-lasting, stable, biocompatible, and nonvolatile antibacterial polymers. In the present study, we incorporated QPEI NP into standard TRMs and examined their influence on dimensional stability and their ability to reduce bacterial leakage. METHOD AND MATERIALS A modified split-chamber model was used in vitro to test calcium sulfate-based and zinc oxide-eugenol- based TRMs (Coltosol and IRM, respectively). Both materials were tested with and without 2% wt/wt incorporated QPEI NP for fluid and bacterial leakage. RESULTS The calcium sulfate-based TRM displayed the lowest microleakage and highest antibacterial resistance. Two-way A NOVA analysis of the fluid transport test results showed that incorporation of 2% wt/wt QPEI NP significantly increased the sealing ability of both TRMs (P < .01). Analysis of survival curves by the Kaplan-Meier method showed that the calcium sulfate-based TRM with 2% wt/wt QPEI NP survived the bacterial load significantly more effectively than did the zinc oxide-eugenol-based TRM (P < .0001). CONCLUSION Incorporation of 2% w/w QPEI NP may prominently improve the sealability and the antibacterial properties of TRMs. TRMs incorporating antibacterial nanoparticles may be clinically advantageous for sealing the endodontic access cavity to avoid reinfection of the root canal system during endodontic treatment.