Effect of a separated rotary instrument on bacterial penetration of obturated root canals

OBJECTIVE: The purpose of this study was to determine the effect of a separated rotary instrument on the time required for bacterial penetration of obturated root canals METHODOLOGY: Twenty-six extracted human mandibular premolars with single canals were used in this study. Group 1 consisted of teeth that contained a separated size 40 K3 rotary file, and were obturated with gutta-percha and AH-26 sealer to the level of the separated file. Group 2 consisted of teeth that were obturated similar to Group 1 but without a separated file. The negative control canals were obturated and had the entire root surface sealed with nail varnish. The positive controls were obturated without sealer. Enterococcus faecalis was placed in the access chamber daily, and penetration was determined when turbidity was noted in the culture broth. RESULTS: The results showed no significant difference between Groups 1 and 2. However, differences between the experimental groups and control groups were statistically significant. CONCLUSION: Under the conditions of the present study, the separated instrument itself does not play a significant role in the sealing ability of the obturation material.     

Effect of gravity and capillarity on human saliva penetration in coronally unsealed obturated root canals

AimThe purpose of this study was to evaluate the effect of gravity and capillarity on penetration of human salivary bacteria into the entire length of obturated root canals, and to demonstrate the dye penetration configuration.Materials and methodsFifty single-rooted premolars were decoronated, prepared to a standardized length of 15 mm, instrumented, and randomly divided into two groups (A and B) of 25 teeth each. Each group consisted of experimental (15 samples) and negative and positive controls (five samples each). The experimental groups were obturated with gutta-percha and root canal sealer. The positive control groups were obturated with a single cone of gutta-percha and root canal sealer. The outer surfaces (except for the apical 2 mm) were covered with two layers of nail varnish. An apparatus containing Brain Heart Infusion broth was designed, in which the teeth were placed. The samples in Group A were placed upside down, while Group B was placed normally. The coronal portions of the samples were placed in contact with fresh saliva. The number of days required for bacteria to penetrate the entire length of canals was determined. The samples were then immersed in India ink to determine the dye penetration configuration. Data were analyzed using Student’s t-test.ResultsThe extent of dye penetration was significantly greater in Group B compared to Group A, and they were in a pattern rather than linear form.ConclusionsGravity and capillarity insignificantly affected bacterial leakage. Although gravity and capillarity did not affect bacterial penetration when applied to the coronal access of endodontically treated teeth, it seems that they can promote penetration of India ink into the canal after the bacterial test on the same tooth.     

Human saliva penetration of root canals obturated with two types of mineral trioxide aggregate cements

The sealing ability of orthograde mineral trioxide aggregate (MTA) root canal filling against human saliva was assessed in vitro. Leakage of gray-colored MTA, white-colored MTA and vertically condensed gutta-percha and sealer were compared. Forty-three extracted single-rooted human teeth were serially instrumented to a file size 40/0.06 at the apex and obturated with either gray-colored MTA (group A), white-colored MTA (group B), or gutta-percha and Kerr Canal Sealer EWT (group C). The teeth were then mounted in a model to test for saliva leakage. After 42 days, one root in group A (9.1%), four roots in group B (36.4%), and nine roots in group C (81.8%) showed saliva leakage. Statistically, a significant difference was found between group A and group C (p < 0.001). No statistical difference was found between group A and group B. Out of the root samples that leaked, the one sample in group A leaked after 36 days. Of the four samples in group B, one sample leaked after 32 days, one sample after 33 days, and two samples after 39 days. All nine samples in group C had leaked after 19 days. It appears that under the conditions of this study both MTA preparations may be more resistant to human saliva leakage than vertically condensed gutta-percha and sealer.     

Bacterial microleakage of barrier materials in obturated root canals

The bacterial microleakage of four current restorative materials (glass ionomer cement, polycarboxylate cement, resin modified glass ionomer cement, and flowable composite resin) used as a base over obturated root canals were evaluated during a 5-month period. Sixty single-rooted mandibular premolars were obturated with cold lateral compaction of gutta-percha. The teeth were randomly divided into five groups of 10 teeth each and positive and negative control groups of five. The access openings were filled with one of the tested barrier materials in four groups. In group 5, no barrier material was placed. Samples were incorporated in a model system using Staphylococcus epidermidis as a microbial marker. Results were analyzed with Kaplan-Meier survival analysis (p = 0.05). The sealing ability of all tested materials was better when compared with group 5 (no barrier material) (p < 0.05). Within the limitations of this study, the glass ionomer cement leaked significantly less when compared with the flowable composite resin (p < 0.05).     

Bacterial leakage versus dye leakage in obturated root canals

AIM: The aim of this study was to compare in vitro bacterial and dye leakage tests, commonly used to determine the seal of root canal fillings. METHODOLOGY: Ninety-six single-rooted teeth had their crowns removed at the cemento-enamel junction and their roots instrumented to ISO size 60 within 1 mm of the apex. Three groups of 30 roots were obturated by lateral condensation using gutta-percha and one or other of the sealers. AH26, Ketac Endo, or Roth's 801 sealer. Three roots were used as negative controls and three roots as positive controls. The roots were then exposed at their coronal end first for 38 days to soy broth containing Staphylococcus epidermidis and thereafter for 48 h to basic fuchsin. Bacterial leakage was recorded when the challenging organism could be recovered from the apical end. Dye leakage was checked by microscopy of transverse sections of the apical tip at the end of the experiment. RESULTS: For the bacterial experiment, there was no significant difference amongst the three sealer groups. The dye experiment showed significantly greater leakage in the AH26 compared to the Ketac Endo group. No correlation between the results of the two tests could be seen. CONCLUSIONS: The results of this study suggest that the molecular size of the penetrating agent may not be the relevant parameter when attempting to determine an appropriate test for the sealability of root canal fillings.     

Sealer distribution in root canals obturated by three techniques

AIM: The aim of this study was to observe sealer distribution in root canals filled by different root filling techniques. METHODOLOGY: AH26 (0.05 mL) dyed with carbon black powder was placed into the prepared root canals of maxillary central incisors using a lentulo spiral. Thereafter the canals were obturated using three different gutta-percha root-filling techniques. Horizontal sections were cut in the apical and middle portions of the filled canals. Images of the cross sections were scanned and the percentage of sealer coated canal perimeter (PSCP) was measured using a computer digital imaging system. RESULTS: At 3 mm from the apex, the PSCP after lateral condensation was similar to that after vertical condensation (P > 0.05). At 6 mm from the apex, however, the PSCP was significantly higher after lateral condensation than after vertical condensation (P < 0.05). At both levels the PSCP was significantly higher after single cone (no condensation) than after the other two condensation techniques (P < 0.0001). CONCLUSIONS: Sealer may be removed from the canal wall by the condensation procedures.     

Gap volume and sealer penetration of C-shaped root canals obturated with cold hydraulic technique and calcium silicate sealer

This study compared the gap volume and sealer penetration in C-shaped root canals prepared with adaptive core rotary files and obturated with cold hydraulic compaction using calcium-silicate sealer, warm vertical hybrid compaction, or lateral compaction using epoxy-resin sealer. Thirty-six extracted mandibular molars with pulpal floor configuration Types I and III were used. The teeth were prepared using XP-Shaper and XP-Finisher and obturated with: group 1: cold hydraulic compaction/calcium silicate, group 2: warm vertical hybrid compaction/epoxy resin, or group 3: lateral compaction/epoxy resin. The gap volume was evaluated using μ-CT. The sealer penetration depth and area were evaluated using confocal laser scanning microscopy. The gap volume in groups 1, 2, and 3 was 0.82%, 0.24%, 0.80%, respectively, which were not significantly different (p > 0.05). The gap volumes in the obturated C-shaped canals were not significantly different among the CHC/CSBS, WHC/ERS, or LC/ERS groups. CHC/CSBS was the most convenient technique.     

The effect of MTAD on the coronal leakage of obturated root canals

The purpose of this study was to evaluate the effect of smear-layer removal using MTAD on coronal leakage of obturated root canals using a dye-leakage test. Fifty, extracted, single-rooted, human teeth were cleaned and shaped and divided into 5 equal groups of 10 each. The smear layer in groups 1 to 3 was left intact. The smear layer in groups 4 and 5 was removed using 17% EDTA or MTAD, respectively. After obturation of root canals, the access opening to each canal was filled with India ink for 48 h. The depth of coronal-dye penetration was measured using the Sigmascan software. ANOVA showed statistically significant differences among the groups (p < 0.05). Samples treated with MTAD yielded significantly less leakage than samples treated with sodium hypochlorite. The amount of dye penetration was not statistically different between teeth treated with MTAD or EDTA (p = 0.062).     

Intraorifice sealing of gutta-percha obturated root canals to prevent coronal microleakage

A study was conducted to evaluate Cavit, Intermediate Restorative Material, and Super-EBA as intraorifice filling materials to prevent coronal microleakage. Root canal instrumentation and obturation was done on 74 extracted single-rooted teeth. Three and one-half millimeters of the gutta-percha was removed from the coronal aspect of the root canal and replaced with one of the three filling materials. The teeth were suspended in scintillation vials containing trypticase soy broth, and human saliva was added to the pulp chambers. Microbial penetration was detected as an increase in turbidity of the broth corresponding to bacterial growth. At the end of 90 days, the results showed that 15% of the Cavit-filled orifices leaked, whereas 35% of the Intermediate Restorative Material and Super-EBA-filled orifices leaked. The gutta-percha obturated root canals that received an intraorifice filling material leaked significantly less than the obturated, unsealed control group--all of which leaked in < 49 days.     

In vitro radiographic representation of the extent of voids within obturated root canals

The aim of this study was to determine whether radiographs provide an accurate representation of the degree of root canal obturation following a cold lateral condensation technique. A total of 40 extracted single-rooted lower premolar teeth were prepared using either a standardized step-back technique or an ultrasonic device by one of two operators. The four groups, each of 10 teeth were obturated using lateral condensation by a third operator. To assess apical leakage the obturated teeth were coated with nail varnish to within 2 mm of the apex and immersed in methylene blue for 48 h. The teeth were then radiographed in bucco-lingual and mesio-distal planes prior to subsequent sectioning in a bucco-lingual plane. Sections and radiographs were analysed using an image analysis apparatus to determine the proportion of root canal occupied by gutta-percha, void and/or sealer. Mean percentages of void calculated from the bucco-lingual radiographs, mesio-distal radiographs and tooth sections were 4.14%, 5.98% and 4.98%, respectively. Statistical analysis showed no significant differences between the radiographic views and the tooth sections (P > 0.05). Both planes of radiograph accurately represented the proportion of void when compared with the tooth section.     

A new instrument for drying root canals

Summary. A new method for drying root canals is reported in which an 'Apical Broach', which resembles a K-file without flutes, is used. Absorbent cotton is wound around it to create an instrument suitable for drying root canals. The apical broachcotton instrument can be made at the chairside and is economical.     

Leakage of bovine serum albumin in root canals obturated with super-EBA and IRM

The aim of this study was to determine the leakage of SuperEBA and intermediate restorative material (IRM) in root canal samples, with or without orthograde filling, by evaluating bovine serum albumin (BSA) microleakage using spectrophotometry. Thirty-five single-rooted teeth were divided into five groups, instrumented, and had apices resected. Root-end cavities in groups I and II were filled with SuperEBA and IRM. The samples from the groups III, IV, and V were filled with gutta-percha and sealer. In groups IV and V, root-end cavities were filled with SuperEBA and IRM. After 60 days, the greatest microleakage of BSA was observed in group II (4.1 +/- 0.0011 ng), followed by group III (3.4 +/- 0.0064 ng), and then group I (2.6 +/- 0.0019 ng). Samples from groups IV and V leaked the least (0.7 +/- 0.0014 ng). Significantly less leakage (p < 0.05) occurred in samples filled with orthograde and root-end fillings than did in samples filled only with an orthograde approach and the samples with IRM root-end fillings.     

Bacterial leakage in obturated root canals following the use of different intracanal medicaments

Abstract – The aim of this study was to examine whether intracanal medication prior to root canal obturation has an inhibitory effect on corono-apical penetration of bacteria. 93 single rooted teeth were instrumented and sterilized with ethylene oxide. They were assigned to three control groups and four test groups with n =20 each. For one week, they were dressed with different medicaments: The first group with a 5% chlorhexidine gel, the second with Ledermix, the third with a fresh mix of calcium hydroxide and water and the fourth without any medication. After obturation (lateral condensation, AH26) the roots were fixed between a top and a bottom chamber. The top chamber contained 3 mL trypticase soy broth with 10⁸ Staphylococcus epidermidis CFU's/mL, whereas the bottom chamber contained sterile trypticase soy broth. For one year, the mounts were incubated at 37°C. They were checked on a regular basis for turbidity in their bottom chambers indicating bacterial growth. None of the test samples leaked for three months. After one year, the calcium hydroxide group had only 6 leaking samples whereas the chlorhexidine group had 14, the Ledermix group 15, and the unmedicated group had 13 leaking samples. It may be concluded that under the conditions of this study, calcium hydroxide was the medicament of choice to avoid bacterial penetration of the root canal. Ledermix did not perform better than no pre-medication. Chlorhexidine was superior to Ledermix in the second third of the observation period.     

Bacterial leakage in obturated root canals following the use of different intracanal medicaments

The aim of this study was to examine whether intracanal medication prior to root canal obturation has an inhibitory effect on corono-apical penetration of bacteria. 93 single rooted teeth were instrumented and sterilized with ethylene oxide. They were assigned to three control groups and four test groups with n = 20 each. For one week, they were dressed with different medicaments: The first group with a 5% chlorhexidine gel, the second with Ledermix, the third with a fresh mix of calcium hydroxide and water and the fourth without any medication. After obturation (lateral condensation, AH26) the roots were fixed between a top and a bottom chamber. The top chamber contained 3 mL trypticase soy broth with 10(8) Staphylococcus epidermidis CFU's/mL, whereas the bottom chamber contained sterile trypticase soy broth. For one year, the mounts were incubated at 37 degrees C. They were checked on a regular basis for turbidity in their bottom chambers indicating bacterial growth. None of the test samples leaked for three months. After one year, the calcium hydroxide group had only 6 leaking samples whereas the chlorhexidine group had 14, the Ledermix group 15, and the unmedicated group had 13 leaking samples. It may be concluded that under the conditions of this study, calcium hydroxide was the medicament of choice to avoid bacterial penetration of the root canal. Ledermix did not perform better than no premedication. Chlorhexidine was superior to Ledermix in the second third of the observation period.     

Effect of Nd:YAG laser irradiation on the apical leakage of obturated root canals: an electrochemical study

AIM: The purpose of this laboratory study was to evaluate the effect of Nd:YAG laser irradiation on the apical leakage of obturated root canals using an electrochemical method. METHODOLOGY: Forty extracted single-rooted teeth were selected and the anatomic crown of each tooth was removed. The specimens were randomly divided into four groups. In group 1, the root canals were prepared with K-files and irradiated with Nd:YAG laser (5 W, 20 Hz) via a 300 microns optical fibre. Then the root canals were obturated with laterally condensed gutta-percha and Pulp Canal Sealer EWT. In group 2, the root canals were treated with the same method as those of group 1 but without laser irradiation. In group 3, the root canals were prepared with ProFiles, laser irradiated and then obturated with vertically condensed gutta-percha and Pulp Canal Sealer EWT. In group 4, the root canals were treated with the same method as those of group 3 but without laser irradiation. The electric resistance between standard and experimental electrodes in the canals was measured over a period of 10 days. RESULTS: At 2 h, groups 1 and 3 irradiated with laser had significantly less apical leakage than group 2 (P < 0.05). After 10 days, group 4 had the highest leakage, followed by groups 2, 1 and 3; the differences between the groups was statistically significant (P < 0.05). CONCLUSIONS: Laser irradiation following root canal preparation reduced apical leakage following root canal obturation.     

Human saliva coronal microleakage in obturated root canals: an in vitro study.

This study assessed salivary penetration through obturated root canals as related to time by using two methods of analysis--histological examination and dye penetrations. A total of 160 human maxillary anterior teeth were instrumented to size 60 Hedstrom file. Ten of the teeth were not obturated; 150 teeth were obturated by lateral condensation of gutta-percha and Roth's root canal sealer. Fifty of these teeth received intermediate restorative material temporaries to a thickness of approximately 3 mm. All teeth were immersed in 50 ml of whole human saliva and kept at 37 degrees C and 100% humidity. The saliva was changed daily. At 2, 7, 14, 28, and 90 days, 32 teeth were removed from the saliva. Of these, two were unobturated and were examined for bacterial penetration by culturing of the apical one-third. Ten teeth without temporaries were immersed in Pelikan ink for 2 days to demonstrate the extent of salivary penetration. These teeth were decalcified and cleared to allow direct measurement of dye penetration. Decalcified serial 7-microns-thick sections were prepared from the remaining 20 teeth, 10 with and 10 without intermediate restorative material temporaries. The sections were stained with hematoxylin and eosin stain and Brown and Hopps stain. Saliva penetration assessed in histological sections was significantly less than was visualized with dye analysis. Salivary penetration at 3 months was significantly greater than at the four earlier study periods. This amount of salivary penetration was considered to be clinically significant. The results strongly suggest retreatment of obturated root canals that have been exposed to the oral cavity for at least 3 months.