Apical Penetration Research Articles

Antimicrobial Efficacy of Different Concentrations of Sodium Hypochlorite in the Elimination of Enterococcus Faecalis: An In-vitro Study

Introduction: Primary teeth are equally important as permanent teeth. Endodontic therapy aids in the preservation and maintenance of extremely carious primary teeth. For root canal therapy to be successful, root canals must be properly prepared and effectively irrigated. Sodium Hypochlorite (NaOCl) has been the gold standard for root canal treatment of primary teeth. However, there are a few drawbacks to using higher concentrations of sodium hypochlorite, such as toxic reactions from its apical penetration. In addition, an excess of irrigation fluid via the apical region could harm the permanent tooth underneath. Therefore, it is crucial to select the proper concentration to preserve the delicate balance between effectiveness and safety. Aim: The present in-vitro study was conducted in the city of Chennai, Tamil Nadu, between March and June 2022. The study aimed to evaluate the effectiveness of lower concentrations of sodium hypochlorite, such as 1%, 0.5%, and 0.25%, against Enterococcus faecalis. Materials and Methods: The antibacterial activity of different concentrations of sodium hypochlorite (1%, 0.5%, and 0.25%) against Enterococcus faecalis was performed using Muller Hinton agar. Three Mueller Hinton agar plates were prepared and sterilised for 15 minutes for each concentration. The volumes used were 25 μL, 50 μL, and 100 μL, respectively. E. faecalis was swabbed and poured into the sterilised plates. The plates were incubated for 24 hours at 37°C. After incubation, the plates were examined, and their zone of Inhibition was determined. ANOVA test was applied with Post-hoc Tukey’s analysis. Results: One-way ANOVA test showed that there was a significant difference with a p-value <0.001 in all three groups. Post-hoc Tukey’s analysis was done, and the test showed that the highest zone of inhibition was seen with 1% sodium hypochlorite at 100 μL, with zone diameter of 39 mm, and the least zone of inhibition was seen with 0.25% sodium hypochlorite solution at 25 μL, with zone diamter of 22 mm. Conclusion: The results of the present study show that a 1% sodium hypochlorite solution can be used to successfully disinfect root canals, indicating its potential as an effective antimicrobial agent in endodontic procedures.

Syringe irrigation in confluent canals: A sequential computational fluid dynamics assessment.

This study aims to assess the influence of root canal preparation, irrigation needle design and its placement depth in the irrigation flow of confluent canals during syringe irrigation. A mandibular molar presenting two confluent canals in its mesial root was sequentially prepared and scanned by micro-computed tomography after mechanical preparation up to ProTaper Next system sizes X2 (25/.06v), X3 (30/.07v) and X4 (40/.06v). In each of the root canal preparation models, a side-vented and an open-ended needle at 5, 3 and 2 mm from the working length were included, and irrigation flow was assessed by a validated computational fluid dynamics model. The results revealed that the irrigant flowed out of the confluent canals mainly through the canal that did not have the needle. Apical penetration and renewal of the irrigant were most efficiently achieved with the use of a 30G open-ended needle and a 30/.07v preparation.

Salivary Gene Expression of RANK, RANKL, and OPG in Type 1 Diabetes Mellitus and Periodontal Disease Patients.

The relationship between type 1 diabetes mellitus (T1DM) and periodontal disease may exhibit by the alteration of bone metabolism. However, evidence for this relationship is scarce and inconclusive. Thus, the aims of the present study were to investigate salivary receptor activator of nuclear factor kappa-β (RANK), receptor activator of nuclear factor kappa-β ligand (RANKL), osteoprotegerin (OPG) gene expression and the RANKL:OPG ratio in T1DM and non-T1DM. Secondary objective was to determine the relationships of RANK, RANKL and OPG gene expression to clinical parameters of T1DM and periodontal disease. Twenty patients with T1DM and twenty age-matched non-T1DM were recruited. Clinical periodontal parameters were measured. Total RNA was isolated from non-stimulated saliva, and the relative gene expressions of RANK, RANKL, OPG and RANKL:OPG ratio were determined by quantitative real-time polymerase chain reaction. The T1DM group had significantly higher mean periodontal parameters than the non-T1DM group, while the mean plaque scores of both groups were not significantly different. There was a trend of higher relative gene expression of RANK, RANKL, and the RANKL:OPG ratio and lower expression of OPG in T1DM group but no statistic significant different when compared to non-T1DM. In the T1DM group, RANKL:OPG correlated with the percentage of bleeding sites, whereas RANK, RANKL, and HbA1c levels correlated with pocket depth. Bone metabolisms demonstrating by decreased OPG gene expression and upregulated of RANK, RANKL, RANKL:OPG with higher pocket depth and bleeding in T1DM may play an important role in periodontal destruction in T1DM.

COMPARISON OF THREE BIOCERAMIC SEALERS IN TERMS OF DENTINAL SEALING ABILITY IN THE ROOT CANAL

Objective: The main objective of endodontic treatment is to prevent further infection or reinfection by eliminating microorganisms within theroot canal system. Proper endodontic treatment could prevent apical and coronal penetration of fluids and microorganisms. Endodontic sealer isvital components of root canal obturation to establish a fluid-tight seal. Bioceramic-based root canal sealers are considered to be an advantageoustechnology in endodontics and have been found to be both biocompatible and comparable to other commercial sealers. The aim of this study was tocompare the adhesion of three bioceramic sealers within the root canal system.Methods: Endodontically treated teeth were obturated using three types of bioceramic sealers and then divided into three groups. Specimens werethen observed using a scanning electron microscope, and the attachment distance was measured using ImageJ.Results: The three groups exhibited were statistically significant differences (p<0.05) in dentinal sealing ability. Calcium phosphate silicate-basedsealer showed the highest sealing ability, followed by pure tricalcium silicate-based bioceramic sealers and then tricalcium silicate and resin-basedbioceramic sealers.Conclusion: The sealing ability of calcium phosphate silicate-based sealer is superior to that of both pure tricalcium silicate-based and tricalciumsilicate- and resin-based sealer.

Age-Dependence of Flow Homeostasis in the Left Ventricle.

Background: Intracardiac flow homeostasis requires avoiding blood stasis and platelet activation during its transit through the cardiac chambers. However, the foundations of intraventricular blood washout and its exposure to shear stresses have been poorly addressed. We aimed to characterize and quantify these features in a wide population of healthy subjects and assess the relationships of these indices with age.Methods: We used color-Doppler echocardiography and custom post-processing methods to study 149 healthy volunteers from 26 days to 80 years old. From the intraventricular flow-velocity fields we obtained personalized maps of (1) the residence time of blood in the LV, and (2) the shear index, a metric accounting for the strongest occurrence of shear stresses inside the chamber. From these maps we derived quantitative indices of the overall intraventricular blood washout and shear exposure. We addressed the age-dependence of these indices and analyzed their relationship with age-related changes in filling-flow.Results: The entire intraventricular blood pool was replaced before 8 cycles. Average residence time of blood inside the LV was <3 cycles in all subjects and followed an inverse U-shape relationship with age, increasing from median (IQR) of 1.0 (0.7 to 1.2) cycles in the 1st year of life to 1.8 (1.4–2.2) cycles in young adults (17–30 years old), becoming shorter again thereafter. Shear index showed no relation with age and was bounded around 20 dyn·s/cm2. Regions with the longest residence time and highest shear index were identified near the apex. Differences in the degree of apical penetration of the filling waves and the duration of the late-filling phase explained the age-dependence of residence time ( = 0.48, p < 0.001).Conclusions: In average, blood spends 1 to 3 beats inside the LV with very low shear stress rates. The apical region is the most prone to blood stasis, particularly in mid-aged adults. The washout of blood in the normal LV is age-dependent due to physiological changes in the degree of apical penetration of the filling waves.

In vitro study of the periapical sealing ability of three root canal sealing cement

Objective: The objective of this study was to determine the sealing ability of different root canal cement: resin AH Plus®, calcium hydroxide Sealapex®, and eugenol zinc oxide Pulp Canal Sealer® by measuring the apical penetration of a dye. Methods: One hundred straight single-canal teeth were biomechanically prepared to 0.5 mm of the apical foramen. The teeth were divided into four groups, three experimental groups, with thirty teeth in each group, and a control group, with ten teeth. The following sealants were selected: AH Plus®, Sealapex®, and Pulp Canal Sealer®. The root canal was not sealed in the control group. Lateral condensation was performed on the experimental groups using gutta-percha. The teeth were immersed in Indian ink to determine leakage. Results: In the experimental groups, ink penetration was observed in about 50% of the teeth. The lowest mean penetration was observed in the AH Plus® group (30.9 (±42.9)), and the highest was observed in Pulp Canal Sealer® (94.35 [±79.9]), (P

HVAD Thrombosis - Searching for the Source

Today sintering of inflow cannulae in left ventricular assist devices (LVAD) is accepted as standard to ensure good myocardial ingrowth, preventing thrombus formation at the apical penetration site. Various studies like the ADVANCE trial compared the formerly polished pump of the HeartWare HVAD and the sintered version commercialized since 2012, investigating the incidence of pump thrombosis and thromboembolic complications. Though this is of essential clinical importance, it is only a surrogate for inflow cannula thrombus development.

Influence of the Calcium Hydroxide Intracanal Dressing on Dentinal Tubule Penetration of Two Root Canal Sealers.

Objective:The aim of this study was to evaluate the effect of a calcium hydroxide (CH) dressing on the tubular penetration of two endodontic sealers, AH Plus (Dentsply Maillefer, Ballaigues, Switzerland) and MTA Fillapex (Angelus, Londrina, Brazil).Methods:Seventy-two mandibular premolars with a single root canal were prepared with ProFile.04 rotary instruments (Dentsply Maillefer) and divided into four groups. In two groups, an intracanal CH dressing was placed for 15 days. The obturations were performed with lateral condensation of gutta-percha in combination with one of the tested sealers. The roots were transversely sectioned at the apical and middle levels. The percentage of sealer penetration in the root canal walls and the percentage of impregnated dentin area in the transverse sections were obtained using confocal laser scanning microscopy. Statistical analysis was performed using one-way analysis of variance (ANOVA) and Games-Howell test.Results:The CH dressing reduced the mean value of tubular penetration in the middle third of teeth obturated with AH Plus (P<0.01), whereas no difference was observed at the apical sections for both sealers.Conclusion:The CH dressing did not interfere with the apical penetration of both tested sealers, however, decreased the tubular penetration in the middle third of the AH Plus root canal fillings. Overall, MTA Fillapex presented higher tubular penetration than AH Plus obturations.

Effect of apical preparation on different needle depth penetration

AimShaping should be complemented by antiseptic solution. These are often delivered using a needle and syringe. But apical penetration of the irrigation solution is of only 1mm beyond its tip. The aim of our study was to evaluate the influence of the apical preparation on the penetration depth of some needles. Methodology24 teeth were divided randomly into two groups and prepared in continuous rotation (350rpm) with Revo-S® or ProTaper® to sizes AS 30, 35 and 40 and F1, F2 and F3 respectively. Four types of endodontic needles were used. Three sizes of stainless steel needles: 25, 27 and 30 gauge and one of nickel–titanium needle: 30 Gauge. Each needle was inserted and its length of penetration measured before the root canal preparation and after the finishing files. ResultsMultivariate analysis of variance showed significant differences for the finishers (p<0.0001) and the kind of needle (p<0.0001). The PLSD Fisher's test can highlight the differences between the six types of apical shaping used (independently of the needle type). The same differences were observed between the four types of needle (independently of the apical finish) (p=0.0232).Variance analysis between the four different needles is statistically significant for each apical shaping (p<0.0001×6). Variance analysis among the six types of finish is statistically significant for each type of needle (p<0.0001×4). ConclusionsThis study shows that the apical preparation influences the penetration depth of needles. The 27 gauge needles reach the last millimetre only with the Revo-S® system shaped with AS 40. Finally, the 30 gauge needles reach it for all finishers except the ProTaper® F1.

Comparison of Pro Root Mineral Trioxide Aggregate and Calcium Enriched Mixture Cement Microleakage as Root End Filling Material: An in Vitro Analysis of Dye Penetration

Background: Sealing ability is an essential factor for retrograde filling material in successful endodontic apical surgery. The aim of this in vitro study was to evaluate dye microleakage of Mineral Trioxide Aggregate (MTA) and Calcium Enriched Mixture (CEM cement) as root end filling material. Objectives: The aim of this in vitro study was to compare sealing ability of these two root end filling materials using the dye penetration method. Materials and Methods: Eighty-six single rooted teeth were randomly divided into two study (n = 40) groups and two positive and negative control (n = 3) groups. After decoronation closely to the cementum enamel junction, the root canals were shaped by the crown down technique and obturated by gutta-percha and AH26 sealer with the lateral condensation method. Furthermore, 3 mm of root ends were resected and 3 mm root-end cavities were prepared by ultrasonic microsurgical tip. Root-end cavities were filled with each of the mentioned materials. Methylene blue dye was used for determination of dye leakage. Chi-2 analysis and t-test were used to compare groups. Results: The mean apical penetration of dye in the MTA group was 0.94 mm while in the CEM cement group this was 1.17 mm. Eighty percent of the MTA group and 75% of the CEM cement group didn’t have any dye leakage. The P level was greater than 0.05 (0.592). Conclusions: There was no significant statistical difference between MTA and CEM cement in sealing ability (P > 0.05).

An investigation of a potential confounder in ex vivo microbiological studies - the bulk flow of fluid through apical foramina during tooth extraction

To investigate the factors affecting bulk flow of dye and bacterial suspensions into and out of apical foramina during simulated tooth extraction, using an ex vivo model. Sixty extracted, single-rooted, human teeth were accessed, root canals located and in 50 the pulps dissolved; 10 teeth with attached periapical lesions were preserved. The size of apical foramina was determined digitally. The teeth were mounted in vials with polyvinylsiloxane impression material. Part 1: different dyes were inoculated in the coronal half of root canals or cervical 'gingival' margin, respectively, in separate experiments using the same teeth. Tooth extraction movements were simulated and apical penetration of the dye solutions with and without coronal restorations were examined in each case (20 teeth re-used 4 × ). Part 2: the same procedures were repeated on 30 more teeth but using a standard inoculum of Acidovorax sp. Part 3: 10 teeth with attached periapical lesions were inoculated with Acidovorax sp. in the absence of coronal restorations. Bacterial leakage into the periapical lesions was assessed. Coronal restorations significantly reduced the flow of dyes (P=0.002) or bacterial suspension (P=0.001) out of the canals and bacterial suspension into (P=0.02) the canals during simulated tooth extraction. The 'size of apical foramina' were positively correlated with passage of bacterial suspension out of the canal (P=0.04) and from the gingival trough into the canal (P=0.008), in the presence of a coronal restoration. The presence of coronal restorations, the size of apical foramina and presence of native canal contents with attached periapical lesions, all influenced fluid flow into and out of canals during simulated tooth extraction movements.

Auswirkungen der Konizität der Aufbereitung auf die Dichtigkeit von 4 Wurzelkanalfüllmethoden in vitro

The aim of this study was to investigate the influence of the preparation taper on the apical leakage of 4 different root canal obturation techniques. A total of n = 165 human straight teeth roots were divided to groups of 15 each and prepared using rotating Ni/Ti and hand instruments to ISO 40 and tapers of 0.02, 0.04 and 0.06. The roots were filled using a central cone technique, lateral condensation, vertical condensation and continuous wave technique (System-B® and Obtura®). The roots were blinded and coated with nail varnish except 1mm above the apex. After immersion in methylene blue, five sections of 0.8 mm step length were done in the apical region. All roots were then cut at a point 6 mm above the apex. The residual root was then exposed to a second dye immersion. Three serial cuts were done in this middle part of the roots. All cuts were digitised. Penetration depth and penetration degree around the root filling were calculated for the middle part of the root and the apical region separately. Results were compared using MANOVA and a significance level of p = 0.05. There was no influence of taper on penetration depth (p = 0.42), apical penetration degree (p = 0.535) or mid root penetration degree (p = 0.054). We found no influence of the filling method on apical penetration degree (p = 0.141) but highly significant influence on the mid root penetration degree (p < 0.001) and the apical penetration depth (p<0.001). The combination of taper and filling method showed a significant influence on apical penetration degree (p = 0.013) and depth (p = 0.031) but no significant influence in the middle part of the root (p = 0.539). The quality of root canal obturation depends on the combination of preparation taper and filling method. The single cone technique shows best results using a taper of 0.02. For lateral condensation technique a taper of 0.04 seems to be more optimal. Vertical condensation techniques perform independently of the preparation taper. None of the filling methods performed superior to the others.

Apical root canal anatomy of canine teeth in cats

Abstract Objective To determine the apical anatomy of canine teeth in cats. Sample Population 70 permanent canine teeth of cats. Procedure The teeth were extracted, cleaned, and radiographed, and the root canals were stained with India ink, then cleared in methyl salicylate. The apical root canal anatomy was studied by examining dental radiographs and microscopic measurements performed on the cleared specimens. Results Apical root canal anatomy in cats has the same "sprinkler-rose" appearance as seen in dogs. The mean length of the radiodense apex on radiographs was 2.8 ± 1.2 mm. The mean lengths of the apical ramifications were 1.9 ± 0.4 and 1.6 ± 0.4 mm for upper and lower canine teeth, respectively; mean numbers of apical ramifications were 13 ± 6 and 12 + 5, respectively; and mean ratios (length of ramifications/length of root) were 0.16 ± 0.03 and 0.15 ± 0.04, respectively. There was significant (P &lt; 0.05) difference in the length of apical ramifications between upper and lower canine teeth and significant (P &lt; 0.05) positive correlation between the length of the root and the length of apical ramifications for all canine teeth. Conclusion Primary apical foramen is not present in mature canine teeth of cats. Clinical Relevance There is little risk of apical penetration by files during endodontic therapy of canine teeth of cats; however, the multiple foramina require that apical instrumentation is thorough to prevent soft tissue remnants causing failure of the procedure. (Am J Vet Res 1996;57:1545–1548)

Evaluation of the apical condensation of gutta-percha by a tapered/calibrated spreader/plugger

This study compared a tapered, calibrated spreader/plugger instrument (M-series) to noncalibrated spreaders and pluggers in achieving apical condensation of gutta-percha in 20 single-rooted human teeth. The distances between the tip of the instruments and the tip of the master gutta-percha were measured. Results showed no significant difference in apical penetration between the D-11 spreader and finger plugger, also no difference between the M-spreader and M-plugger. The mean distance was significantly larger for the D-11 spreader than that for the M-spreader or M-plugger at 99% confidence level. The mean distance of the finger pluggers was significantly higher than that for the M-spreader at the 95% confidence level. Microleakage evaluation of the obturated teeth did not show a statistically significant difference between all four instruments used in this in vitro study.

Results of a multicenter study of the modified hook[mdash ]titanium Greenfield filter

Initial efforts to modify the stainless steel Greenfield filter for percutaneous insertion led to development of a titanium Greenfield filter, which could be inserted by use of a 12F carrier. This device functioned well as a filter but had an unacceptable 30% rate of migration, tilting, and penetration. Therefore a titanium Greenfield filter with modified hooks was developed and has been tested in 186 patients at 10 institutions. Successful placement occurred in 181 (97%); placement of the remainder was precluded by unfavorable anatomy. A contraindication to anticoagulation was the most frequent indication for insertion (75%). All but two were inserted percutaneously, predominantly via the right femoral vein (70%). Initial incomplete opening was seen in four patients (2%), which was corrected by guide wire manipulation and asymmetry of the legs in 10 (5.4%). Insertion site hematoma occurred in one patient, and apical penetration of the cava during insertion occurred in a second patient. Both events were without sequelae. Follow-up examinations were performed at 30 days at which time 35 deaths had occurred. Recurrent embolism was suspected in six patients (3%) and two of three deaths were confirmed by autopsy. Filter movement greater than 9 mm was seen in 13 patients, (11%) and increase in base diameter greater than or equal to 5 mm was seen in 17 patients (14%). CT scanning showed evidence of caval penetration in only one patient (0.8%). Insertion site venous thrombosis was seen in 4/46 (8.7%) patients screened. The modified hook titanium Greenfield filter is inserted percutaneously or operatively through a sheath, eliminating concern for misplacement from premature discharge.(ABSTRACT TRUNCATED AT 250 WORDS)

Results of a multicenter study of the modified hook—titanium Greenfield filter

Initial efforts to modify the stainless steel Greenfield filter for percutaneous insertion led to development of a titanium Greenfield filter, which could be inserted by use of a 12F carrier. This device functioned well as a filter but had an unacceptable 30% rate of migration, tilting, and penetration. Therefore a titanium Greenfield filter with modified hooks was developed and has been tested in 186 patients at 10 institutions. Successful placement occurred in 181 (97%); placement of the remainder was precluded by unfavorable anatomy. A contraindication to anticoagulation was the most frequent indication for insertion (75%). All but two were inserted percutaneously, predominantly via the right femoral vein (70%). Initial incomplete opening was seen in four patients (2%), which was corrected by guide wire manipulation and asymmetry of the legs in 10 (5.4%). Insertion site hematoma occurred in one patient, and apical penetration of the cava during insertion occurred in a second patient. Both events were without sequelae. Follow-up examinations were performed at 30 days at which time 35 deaths had occurred. Recurrent embolism was suspected in six patients (3%) and two of three deaths were confirmed by autopsy. Filter movement > 9 mm was seen in 13 patients, (11%) and increase in base diameter ≥5 mm was seen in 17 patients (14%). CT scanning showed evidence of caval penetration in only one patient (0.8%). Insertion site venous thrombosis was seen in 4/46 (8.7%) patients screened. The modified hook titanium Greenfield filter is inserted percutaneously or operatively through a sheath, eliminating concern for misplacement from premature discharge. The modified hook design has reduced the incidence of migration and caval penetration, but proper orientation of the carrier in the vena cava is necessary to avoid leg asymmetry. No evidence was found of filter occlusion, but longer follow-up is needed to confirm late patency equivalent to the standard Greenfield filter.

Statistical Models for Evaluating the Penetrating Ability of Endodontic Instruments

An in vitro study was conducted to evaluate the penetrating ability of hand instruments (No. 10 K-file and "Pathfinder") and an automated device with a No. 08 (Canal Finder System) file in 270 extracted curved and narrow molar roots. The roots were randomly allocated to six groups, each one corresponding to a different permutation of the three instruments. The experiment was performed in three sequential stages, and Stages II and III were undertaken only in roots where no apical penetration was achieved in the previous stage(s). Statistical models were designed to fit the resulting clinical data. The No. 08 Canal Finder System and No. 10 K-file proved to be similar in their penetrating ability in Stage I (with estimated probabilities of 71.1% and 68.8%, respectively). The No. 08 Canal Finder was found to be the most efficient in Stage II and especially in Stage III, with a probability of penetration of 20.7%, compared with 9.8% for the "Pathfinder" and 7.4% for the No. 10 K-file.

The effect of standard or serial preparation on single cone obturation.

Summary. This leakage study, in vitro, used methylene blue dye as a marker to detect the extent of apical fluid penetration after buccal roots from maxillary first bicuspids were instrumented either by the standard technique or serially, and obturated with laterally condensed gutta‐percha and sealer, a single gutta‐percha master cone and sealer, or sealer alone. The linear extent of dye penetration was measured after the roots were split longitudinally. In this study the laterally condensed gutta‐percha and sealer technique resulted in the least apical penetration of dye. The single gutta‐percha cone and sealer technique groups had less dye penetration than the groups where obturation was with sealer alone. The use of the standard or serial technique of preparing canals resulted in no significant difference in the quality of obturation using a single gutta‐percha cone with sealer or using sealer alone.

Access to subgingival plaque by disclosing agents using mouthrinsing and direct irrigation.

Teeth destined for extraction and exhibiting periodontal pockets had reference grooves cut on the proximal surfaces at the level of the gingival margin. A disclosing agent was then applied either as a mouthrinse or by direct irrigation at the entrance of the pocket. After extraction, the extent of apical penetration of the solution was measured from the reference point. Subsequently, the tooth was stained enabling similar measurements from the reference point to the level of the apical plaque border and the coronal level of the residual periodontal ligament. Analysis of these measurements indicated that neither mouthrinsing nor direct irrigation routinely achieved penetration of the solution to the apical plaque border. While mouthrinsing failed to achieve any significant penetration of pockets, the direct irrigation technique was partially effective. It was concluded that direct irrigation offers promise as a mode of application of chemical agents to subgingival plaque.

An in vivo evaluation of the penetration of an irrigating solution in root canals

Nineteen roots with vital pulps and 19 roots with necrotic pulp tissue were hiomechanically cleansed according to a standardized procedure of instrumentation. A radiopaque material was used as an irrigant to delineate apical penetration in vivo. Extrusion of the irrigant occurred in cases with vital pulps and in cases with necrotic pulp tissue. The solution was confined to the instrumented space in vital cases, whereas the irrigating agent occupied random dimensions of the periapical lesions in some teeth with necrotic pulp tissue. The solution reached the apex of the preparation sooner in teeth with necrotic pulps than in teeth with vital pulps.