Root canal preparation in 3-rooted maxillary premolars through hand, rotary, and reciprocating techniques: a microcomputed tomography evaluation.

Endodontic management of 3-rooted maxillary premolars is a challenge due to their complex anatomy and narrow root canal walls. This study aimed to evaluate, by microcomputed tomography (µCT), the apical enlargement and centering ability promoted by hand, rotary, and reciprocating instrumentation in 3-rooted maxillary premolars. Eighteen teeth were divided into 3 groups (n = 6) according to the preparation technique: crown-down hand, rotary, and reciprocating instrumentation. Instruments with similar apical diameters were used (25 and 40 mm for buccal and palatal canals, respectively). Centering ability and canal enlargement were evaluated through the comparison of µCT images obtained before and after instrumentation. Distances of 0, 2, 4, and 6 mm from the apical stop were considered. Differences between canal areas before and after instrumentation were calculated. In addition, distances between the original canal center and the prepared canal center at the apical stop were measured in both the mesiodistal and buccopalatal directions. Significant differences in enlargement areas and centering ability among the techniques were determined using 2-way analysis of variance and Tukey post hoc test (P > 0.05). Root canal enlargement was similar for all techniques. Excessive enlargement was observed in only a few specimens, and root perforation did not occur. Some specimens presented untreated canal areas. In mesiobuccal and distobuccal roots, reciprocating instrumentation promoted more centered preparations than hand instrumentation when measured in the mesiodistal direction (P > 0.05). There were no other statistically significant differences. The results established that hand, rotary, and reciprocating techniques presented similar safety margins for instrumentation of the apical third of 3-rooted maxillary premolars. Reciprocating instrumentation presented some advantages over hand preparation regarding centering ability.

Three-rooted premolar analyzed by high-resolution and cone beam CT.

OBJECTIVES: The aim of this study was to analyze the variations in canal and root cross-sectional area in three-rooted maxillary premolars between high-resolution computed tomography (µCT) and cone beam computed tomography (CBCT). MATERIALS AND METHODS: Sixteen extracted maxillary premolars with three distinct roots and fully formed apices were scanned using µCT and CBCT. Photoshop CS software was used to measure root and canal cross-sectional areas at the most cervical and the most apical points of each root third in images obtained using the two tomographic computed (CT) techniques, and at 30 root sections equidistant from both root ends using µCT images. Canal and root areas were compared between each method using the Student t test for paired samples and 95 % confidence intervals. RESULTS: Images using µCT were sharper than those obtained using CBCT. There were statistically significant differences in mean area measurements of roots and canals between the µCT and CBCT techniques (P < 0.05). Root and canal areas had similar variations in cross-sectional µCT images and became proportionally smaller in a cervical to apical direction as the cementodentinal junction was approached, from where the area then increased apically. CONCLUSION: Although variation was similar in the roots and canals under study, CBCT produced poorer image details than µCT. CLINICAL RELEVANCE: Although CBCT is a strong diagnosis tool, it still needs improvement to provide accuracy in details of the root canal system, especially in cases with anatomical variations, such as the three-rooted maxillary premolars.

Comparative study of Vertucci and Ahmed classifications to evaluate the main root canal configuration of mandibular incisors in a Brazilian population.

This study aimed to compare the main root canal configurations of mandibular incisors (MI) in a Brazilian population using Vertucci and Ahmed et al. classifications. One hundred and sixty-five human permanent MI were scanned using a micro-CT. Two examiners classified the samples according to Vertucci and Ahmed et al. classification. Kappa coefficient was employed. The majority of MI had a single root canal (52.1%). Type III Vertucci and 1 MI1-2-1 Ahmed et al. was the most common 2-canal MI (20%). In the apical third, the presence of one, two and three canals was found in 81.8%, 15.2% and 3% respectively. In the cervical and middle thirds, one, two and three canals were found in 86%, 12.2% and 1.8% respectively. Ahmed et al. classification was able to classify the entire sample studied, whereas 11 teeth (6.66%) did not fit Vertucci's classification.

LPS levels in root canals after the use of ozone gas and high frequency electrical pulses.

The present study aims to verify the effect of ozone gas (OZY® System) and high frequency electric pulse (Endox® System) systems on human root canals previously contaminated with Escherichia colilipopolysaccharide (LPS). Fifty single-rooted teeth had their dental crowns removed and root lengths standardized to 16 mm. The root canals were prepared up to #60 hand K-files and sterilized using gamma radiation with cobalt 60. The specimens were divided into the following five groups (n = 10) based on the disinfection protocol used: OZY® System, one 120-second-pulse (OZY 1p); OZY® System, four 24-second-pulses (OZY 4p); and Endox® System (ENDOX). Contaminated and non-contaminated canals were exposed only to apyrogenic water and used as positive (C+) and negative (C-) controls, respectively. LPS (O55:B55) was administered in all root canals except those belonging to group C-. After performing disinfection, LPS samples were collected from the canals using apyrogenic paper tips. Limulus Amoebocyte Lysate (LAL) was used to quantify the LPS levels, and the data obtained was analyzed using one-way ANOVA. The disinfection protocols used were unable to reduce the LPS levels significantly (p = 0.019). The use of ozone gas and high frequency electric pulses was not effective in eliminating LPS from the root canals.

In vitro antibacterial activity of a silicone-based endodontic sealer and two conventional sealers.

The aim of this study was to evaluate whether the modification in the silver component is capable of providing GuttaFlow 2 with antibacterial activity against Enterococcus faecalis compared with epoxy resin-based (AH Plus) and zinc oxide and eugenol-based (Endofill) sealers. The antibacterial activity was evaluated using a reference strain of E. faecalis (ATCC 29212). Freshly mixed sealers were subjected to the agar diffusion test (ADT), while the direct contact test (DCT) was performed after materials setting. ADT results were obtained through measurements, in millimeters, of the inhibition zones promoted by the materials, using a digital caliper. In DCT, values of CFU/mL promoted by the three sealers were compared in three experimental periods (1 min, 1 h, and 24 h). The data were analyzed using Kruskal-Wallis and Dunn post-hoc tests (p < 0.05). In both ADT and DCT, GuttaFlow 2 presented no effect against E. faecalis, while Endofill and AH Plus showed similar inhibition zones. Endofill was the only material capable of reducing bacterial growth in DCT. In conclusion, modifications in the silver particle of GuttaFlow 2 did not result in a sealer with antibacterial effect against E. faecalis.

Bovine Pulp Tissue Dissolution Ability of Irrigants Associated or Not to Ultrasonic Agitation.

The aim of this study was to evaluate the tissue dissolution ability of different irrigating solutions associated or not to ultrasonic agitation. Ninety bovine pulp fragments (n=10 per group) were weighed and then placed individually in Eppendorf test tubes containing the following irrigants: G1- 2.5% sodium hypochlorite (NaOCl); G2- 2.5% NaOCl + ultrasonic agitation (US); G3- 2.5% NaOCl + 0.2% cetrimide (CTR); G4- 2.5% NaOCl + 0.2% CTR + US; G5- 400 ppm Sterilox (SX); G6- SX + US; G7- 0.2% CTR; G8- 0.2% CTR + US; G9- saline solution. Two blinded observers assessed the samples continuously for the first 4 h, and then every hour for the next 12 h. Dissolution speed was calculated by dividing the initial pulp weight (mg) by the period of time until complete dissolution (min). Data were compared by ANOVA and Tukey post hoc test with a 5% significance level. G1 to G4 dissolved pulp fragments completely and G2 was significantly faster than the other groups. G5 to G9 did not exhibit dissolving activity. In conclusion, only groups containing NaOCl were capable of pulp tissue dissolution, which was enhanced by ultrasonic agitation, but did not alter when 0.2% cetrimide was associated. This isolated solution and Sterilox showed no dissolving capacity, regardless the use of ultrasound.

Effect of different irrigating solutions and photo-activated therapy for in vivo root canal treatment.

This study aimed to evaluate histologically the effect of irrigation with 400 ppm Sterilox, 2% and 5% sodium hypochlorite (NaOCl), with and without photo-activated therapy (PAD), in a single-visit root canal treatment of dog's teeth with apical periodontitis (AP). Ten dogs were randomly divided into two groups (n=5): with and without PAD, and the root canals into four subgroups, according to the irrigating solution: SX (400 ppm Sterilox), SH2 (2% NaOCl), SH5 (5% NaOCl) and SS (saline solution) as positive control. A total of 134 root canals were opened and left exposed to the oral environment for 14 days and then sealed for 60 days for AP induction. Then, root canals were treated according to each proposed disinfecting protocol and filled in the same session. After 120 days, the dogs were euthanized and the periapical inflammatory events were evaluated under light microscopy. Qualitative data were submitted to Kruskal-Wallis and Mann-Whitney tests (α=0.05). PAD did not produce significant differences in the scores for apical inflammation when used after chemo-mechanical preparation (p>0.05). The irrigating solutions SX, SH2 and SH5 without PAD were statistically different from SS (p<0.05) that presented the greatest scores for apical inflammation. PAD did not show any additional effect for the treatment of root canals with pulp necrosis and AP in a single visit and 400 ppm Sterilox may be considered an alternative to NaOCl in root canal treatment.

Are bovine teeth a suitable substitute for human teeth in in vitro studies to assess endotoxin load in root canals?

The present study aimed to determine the feasibility of using bovine teeth as a suitable alternative for human teeth, in experiments involving in vitro endotoxin contamination. Twenty bovine central incisors and 20 human single-root premolars had their dental crowns removed and root lengths set at 16 mm. Root canals were prepared up to #60 K-file size and sterilized with cobalt-60 gamma irradiation (20 kGy, 6 h). The teeth were randomly divided into four groups: G1-bovine teeth (bovine negative control, n = 10), G2-human teeth (human negative control, n = 10), G3-bovine teeth, inoculated with Escherichia coli (055:B55) LPS, and G4-human teeth inoculated with E. coli LPS. The G1 and G2 groups were exposed to apyrogenic water. After the teeth had been incubated at 37 °C and atmospheric humidity for 24 h, the samples of solutions in the main canals were collected with apyrogenic absorbent paper tips. LPS levels were quantified using Limulus Amebocyte Lysate assay. The data obtained were statistically analyzed using one-way ANOVA, with a significance level of 5%. A high amount of endotoxin was detected in the inoculated human teeth (G4) when compared to the sterilized teeth (G2), as well as in the inoculated bovine teeth (G3) when compared to the inoculated human teeth (G4). However, there was no statistical difference between bovine teeth before and after the E. coli endotoxin inoculation. Therefore, under the mentioned experimental conditions, the use of bovine teeth should not be a choice for laboratory research on endotoxin contamination.

QMix® irrigant reduces lipopolysacharide (LPS) levels in an in vitro model.

The presence of endotoxin inside the root canal has been associated with periapical inflammation, bone resorption and symptomatic conditions.Objectives To determine, in vitro, the effect of QMix® and other three root canal irrigants in reducing the endotoxin content in root canals.Material and Methods Root canals of single-rooted teeth were prepared. Samples were detoxified with Co-60 irradiation and inoculated with E. coli LPS (24 h, at 37°C). After that period, samples were divided into 4 groups, according to the irrigation solution tested: QMix®, 17% EDTA, 2% chlorhexidine solution (CHX), and 3% sodium hypochlorite (NaOCl). LPS quantification was determined by Limulus Amebocyte Lysate (LAL) assay. The initial counting of endotoxins for all samples, and the determination of LPS levels in non-contaminated teeth and in contaminated teeth exposed only to non-pyrogenic water, were used as controls.Results QMix® reduced LPS levels, with a median value of 1.11 endotoxins units (EU)/mL (p<0.001). NaOCl (25.50 EU/mL), chlorhexidine (44.10 EU/mL) and positive control group (26.80 EU/mL) samples had similar results. Higher levels were found with EDTA (176.00 EU/mL) when compared to positive control (p<0.001). There was no significant difference among EDTA, NaOCl and CHX groups. Negative control group (0.005 EU/mL) had statistically significant lower levels of endotoxins when compared to all test groups (p<0.001).Conclusion QMix® decreased LPS levels when compared to the other groups (p<0.001). 3% NaOCl, 2% CHX and 17% EDTA were not able to significantly reduce the root canal endotoxins load.

Effect of superoxidized water and sodium hypochlorite, associated or not with EDTA, on organic and inorganic components of bovine root dentin.

INTRODUCTION: This study aimed to evaluate the effects of Sterilox (Sx), a superoxidized water, 5% and 2% sodium hypochlorite (5NaOCl and 2NaOCl), and 17% EDTA (E) on the organic and inorganic components of bovine dentin. METHODS: Eighty bovine incisors were randomly divided into 8 groups (n = 10): 5NaOCl, 5NaOCl + E, 2NaOCl, 2NaOCl + E, Sx, Sx + E, E alone, and distilled water (H2O). Root canal instrumentation was performed by using the corresponding irrigant. The apical 15 mm was longitudinally sectioned into 2 fragments, one for light microscopy analysis in slides stained with picrosirius red (organic component) and the other for scanning electron microscopy analysis (inorganic component). Scores data obtained in the light microscopy analysis were submitted to the Kruskal-Wallis test, followed by multiple comparisons test (P < .05). Scanning electron microscopy images were analyzed descriptively. RESULTS: The chemical solution 5NaOCl had a greater effect on the organic component of dentin in area and depth than 2NaOCl. The chemical solutions 5NaOCl + E, 5NaOCl and 2NaOCl + E caused the greatest change in the collagenous organic matrix near the root canal lumen. The chemical solution 2NaOCl showed similar behavior to Sx, associated or not with E, promoting more superficial disorganization of collagen in a smaller area. Demineralization was observed in all groups in which E was used. However, areas of erosion and open dentinal tubules were detected only when it was combined with NaOCl. CONCLUSIONS: Five percent NaOCl promoted the most extensive damage to the organic component of dentin, and when associated to EDTA, dentinal erosion could be seen. Considering these specific aspects, 2% NaOCl and Sx had milder effects on bovine root dentin.

Accuracy of cone-beam computed tomography and periapical radiography in apical periodontitis diagnosis.

INTRODUCTION: This study aimed to investigate the correlation and the agreement between periapical radiography (PR) and cone-beam computed tomography (CBCT) correlating to histologic findings in the diagnosis of apical periodontitis (AP). METHODS: One hundred thirty-four premolar root canals from 10 dogs were treated after AP induction. Four months later, the animals were killed, and standard digital PRs were obtained. The area of AP was measured by using ImageJ software. CBCT (i-CAT) images from each arch were obtained, and AP area and volume were measured by using Osiri-X software. The apical inflammatory infiltrate was evaluated under light microscopy. The correlation between imaging methods was evaluated by using the Pearson coefficient. The Bland-Altman method was used to assess the agreement between PR and CBCT data. The Spearman coefficient was used to correlate the imaging data and histologic findings. RESULTS: Despite a strong correlation between PR and CBCT areas, the agreement limits were very broad (95% limits of agreement, 0.19-1.08). PR only measured, on average, 63% of CBCT values. Although there was a strong correlation between PR area and CBCT volume, the Bland-Altman method suggests that the larger the CBCT volume, the more underestimated the PR value. When APs had a volume smaller than 6 mm(3), the PR estimation of CBCT data was unpredictable. A positive correlation was found for PR area, CBCT area, CBCT volume, and histology data. CONCLUSIONS: The diagnosis of AP based on PR data is clinically limited, and it should not be used for scientific investigations.

Management of type III dens invaginatus in a mandibular premolar: a case report.

Dens invaginatus is a well-known malformation of teeth, which probably results from an invagination of enamel organ into dental papilla during tooth development. The endodontic treatment of invaginated teeth may be challenging due to difficulties in accessing the root canals and also due to complex variations of internal morphology. This article presents the endodontic management and follow-up in a rare case of right mandibular second premolar with Oehlers' type III dens invaginatus. The result of cold pulp testing was positive for this tooth but it was associated to a sinus tract and periapical lesion. Herein, it is described the root canal therapy of this tooth combined with periapical surgery, emphasizing the importance of proper diagnosis and planning by using cone beam computed tomography (CBCT). This case report presents the proper periapical healing 6 months after the combination of nonsurgical and surgical treatments. It also shows that CBCT is an important auxiliary examination to avoid errors in diagnosis and subsequent treatment of dental anomalies.

Effect of super-oxidized water, sodium hypochlorite and EDTA on dentin microhardness.

The present study aimed to evaluate the influence of the following irrigating solutions on the microhardness of root canal dentin: 2% sodium hypochlorite (2NaOCl), 5% sodium hypochlorite (5NaOCl), super-oxidized water (400 ppm Sterilox - Sx) and 17% EDTA (E). Eighty roots from bovine incisors were randomly divided into 8 groups (n=10): 2NaOCl, 5NaOCl, Sx, and 2NaOCl + E, 5NaOCl + E, Sx + E (associated with E as final irrigant for 5 min), E solely and distilled water (dH2O) as the negative control. Root canal preparation was performed by hand instruments, using one of the irrigation protocols for 30 min. Then, 5 mm of the cervical root third were cut out from each sample and subjected to the Vickers microhardness test, at two points, one at approximately 500-1000 µm from the root canal lumen (distance 1), and the other at approximately 500-1000 µm from the external root surface (distance 2). Data were analyzed by Wilcoxon and Kruskal-Wallis tests at 5% significance level. Microhardness values at distance 1 were significantly lower than those at distance 2 for all groups, except 5NaOCl and 5NaOCl + E groups (p>0.05). EDTA showed the lowest microhardness values. However, no statistically significant difference was detected among groups at distance 1 and EDTA was significantly different only from Sx at distance 2. In conclusion, all tested solutions showed lower microhardness at the most superficial root canal dentin layer compared to the one found near the external root surface, except 5NaOCl and 5NaOCl + E; EDTA promoted lower microhardness values in comparison to Sterilox at this site.

Cutting efficiency of conventional and martensitic nickel-titanium instruments for coronal flaring.

INTRODUCTION: This study aimed at evaluating the influence of rotational speed and number of uses on the cutting efficiency of 4 nickel-titanium coronal flaring instruments against 2 substrates, bovine dentin and acrylic blocks. METHODS: BioRaCe BR0, HyFlex CM1, ProFile OS#2, and ProTaper Sx were used in simulated lateral action against both substrates at 250 and 500 rpm up to 5 times, producing 5 notches in each block. Notch areas and lengths were measured under a stereomicroscope, and data were compared by using parametric tests (α = 0.05). RESULTS: Against both substrates, HyFlex CM1 and ProFile OS#2 were the most and the least cutting efficient instruments, respectively (P < .05). Against acrylic, area and length values at 500 rpm were significantly higher than those at 250 rpm for all brands. Against dentin, significant differences were detected between 250 and 500 rpm for HyFlex CM1 and ProTaper Sx (area) and for BioRace BR0, HyFlex CM1, and ProTaper Sx (length). Regarding cutting efficiency loss, area and length for notches 1 and 2 (first notches) and 4 and 5 (last notches) were similar against acrylic. Against dentin, length values for notches 1 and 2 were significantly higher than those for notches 4 and 5 in ProFile OS#2 and ProTaper Sx. A strong correlation was detected between the overall results obtained on acrylic and dentin for area and length (P < .0001), although further analysis showed that data against acrylic were a poor predictor of data against dentin after repeated use. CONCLUSIONS: HyFlex CM1 was the most cutting efficient instrument in lateral action. An increase in rotational speed improved the cutting efficiency. Results against acrylic showed a high correlation to data against dentin, but acrylic may not be a proper substrate when the intention is to assess cutting efficiency loss with repeated use.

Dentin inhibits the antibacterial effect of new and conventional endodontic irrigants.

INTRODUCTION: This in vitro study aimed to compare the antibacterial effect of a new irrigant, QMiX, with that of conventional irrigation solutions in the presence or absence of dentin powder. METHODS: Dentin powder was prepared from bovine incisors and sterilized. The following irrigants were tested against Enterococcus faecalis (ATCC 29212): 6% sodium hypochlorite (NaOCl), 1% NaOCl, QMiX, 2% chlorhexidine gluconate (CHX), and 17% EDTA. Sterilized saline solution was used as negative control. Survival of bacteria exposed to the irrigants in the presence or absence of dentin was monitored under planktonic conditions. Colony-forming units were counted, and log-transformed numbers were analyzed by using Kruskal-Wallis and Mann-Whitney tests. P values less than .05 were considered significant. RESULTS: In the absence of dentin, after 10 seconds of contact with the bacterial suspension, 6% NaOCl showed the lowest bacterial count; the difference to the negative control was significant. After 30 seconds, 6% NaOCl displayed 0 colony-forming units per milliliter, whereas 1% NaOCl and QMiX showed reduced number of colonies in comparison with the negative control. After 1 minute, both concentrations of NaOCl presented no bacterial growth and QMiX reduced the number of colonies, but EDTA and CHX had bacterial counts similar to the negative control. Dentin had a significant inhibitory effect on 6% NaOCl (10 seconds), 1% NaOCl (10 seconds and 1 minute), and QMiX (10 seconds and 1 minute). After 6 hours, both concentrations of NaOCl, QMiX, and CHX killed all bacteria, regardless of the presence of dentin. CONCLUSIONS: Six percent NaOCl was the most effective irrigant against E. faecalis. Saline and EDTA had no measurable antibacterial effect. Dentin delayed the antibacterial activity of NaOCl and QMiX but did not completely prevent their action.

Apical resorption in teeth with periapical lesions: correlation between radiographic diagnosis and SEM examination.

This study correlated the radiographic findings and scanning electron microscopy (SEM) images of external apical resorption (EAR) in teeth with periapical lesions. Standard radiographs were taken from 45 teeth with periapical lesions before their extraction. Using a radiographic examination, the root apex of each tooth was classified according to the EAR into the following categories: radiographic external apical resorption (REAR) absent, superficial and deep. The apical root surface was also examined with SEM. Photomicrographs of EARs were classified as periforaminal (PEAR) and foraminal (FEAR) in three degrees: 0, 1 and 2. REAR was present in 72.5% of cases, of which 20% were deep. Based upon SEM analysis, PEAR and FEAR occurred in 75.6% and 66.7% of cases respectively; 51.2% and 59% respectively, of these teeth received a score of 2. Only 15.4% of the specimens were unaffected by EAR. When teeth with periapical lesions were examined for EAR with both radiography and by SEM, there was no correlation between the findings.

Effectiveness of lateral and secondary canal filling with different endodontic sealers and obturation techniques

Objective: this study aimed to compare the performance of the new endodontic sealer GuttaFlow 2 (GF2) with two conventional sealers - AH Plus (AHP) and EndoFill (EF) - for filling artificial lateral and secondary canals with the following two obturation techniques: cold lateral condensation (CLC) and Tagger's hybrid technique (THT). Materials and method: sixty single-rooted human teeth were selected and subjected to root canal preparation. Next, specimens were subjected to a diaphanization method. During this process, artificial lateral and secondary canals were produced at 2, 5, 9, and 12 mm from the root apex. The specimens were randomly assigned into six groups (n = 10) according to endodontic sealer (GF2, AHP, or EF) and obturation technique (CLC or THT). The filling of lateral and secondary canals was analyzed by stereomicroscopy. The images were obtained and transferred to the ImageJ software. The mean filling percentages were calculated considering total linear measurements of artificial canals and their filled portions. Data were compared by two-way Anova, followed by Bonferroni Post-Hoc Test, at 5% significance level. Results: all materials showed the ability to penetrate into artificial lateral and secondary canals. There was no significant difference (P>0.05) between sealers and obturation techniques. Only GF2 showed a significantly improved flow into lateral canals when compared to secondary canals (P<0.05). Conclusion: GF2 shows proper flow for filling ramifications of the main root canal, but presents no advantage over conventional zinc oxide-eugenol-based or epoxy resin-based filling materials.

Clinically relevant dimensions of 3-rooted maxillary premolars obtained via high-resolution computed tomography.

INTRODUCTION: This study aimed to characterize the dimensions of a selection of 3-rooted maxillary premolars through high-resolution computed tomographic analysis considering measures of clinical interest for root canal treatment, such as root wall thickness, canal diameters, and distances between 2 canals in fused roots and between the root apex and foramen. METHODS: Fifteen 3-rooted human maxillary premolars extracted for therapeutic reasons were individually scanned using a high-resolution desktop high-resolution computed tomographic system. Starting from the apical foramen, the selected cross-sectional images corresponding to each millimeter of the roots were evaluated. Measures of clinical interest were determined using Image J software (version 1.41; National Institutes of Health, Bethesda, MD). RESULTS: Root wall thickness as thin as 0.4 and 0.6 mm was detected in the apical portion of buccal and palatal roots, respectively. In the cervical portion, buccal roots had narrower root walls (0.817-1.670 mm) compared with palatal roots (1.361-2.720 mm). In all thirds, the palatal canal was wider compared with the mesiobuccal and distobuccal canals. In the buccopalatal direction, all roots had thicker root walls toward the furcation, whereas in the mesiodistal direction the mesiobuccal and distobuccal roots had the thinnest walls along their distal and mesial aspects, respectively. Both buccal canals revealed dentin apposition 2 mm from the canal orifice, resulting in cervical constriction. Generally, the distance between the root apex and the foramen was greater in distobuccal roots in comparison with the others with a tendency for foramina to be eccentric. CONCLUSIONS: Three-rooted premolars are a clinical challenge not just because of their low frequency and difficulties regarding diagnosis and root canals access but also because of their fragile roots. These phenomena are critical in terms of the amount of dentin removed during the preparation of root canals and during post space preparation.

Influence of the instrumentation technique and apical preparation diameter on calcium hydroxide filling in simulated curved canals.

OBJECTIVE: This study evaluated the influence of the instrumentation technique and apical preparation size on the filling capacity of a calcium hydroxide (CH)-based paste. MATERIALS AND METHODS: Fifty simulated curved canals were prepared in acrylic blocks (five groups; n = 10 each). In three groups, the canals were preflared with Gates-Glidden drills and the apical stop was prepared with #25, 30 or 35 Flexofile files. In the other two groups, the canals were prepared with ProTaper rotary instruments and the apical stop was prepared with F1 and F2. A CH paste was injected into the canals using a special syringe. The four sides of the blocks were scanned with the root curvature to the mesial, buccal, distal and palatal faces. The amount (%) of filling in the total canal area and in the apical 5 mm was obtained [analysis of variance (ANOVA); Tukey's test; α = 0.05]. Qualitative analysis of apical filling was done (absence vs. presence of filling deficiencies) (chi-square test; α = 0.05). RESULTS: There was no significant difference in canal filling among the groups at any block side. Presence of voids was associated with the simulated mesial and distal faces. CONCLUSIONS: An effective canal filling with the CH paste was not achieved in all cases. Canal filling failure occurred mostly in the apical third. Filling deficiencies can be better visualized in canals with mesial and distal root curvatures.

An in vivo radiographic evaluation of the accuracy of Apex and iPex electronic Apex locators.

The aim of this study was to evaluate in vivo the clinical applicability of two electronic apex locators (EALs) - Apex (Septodont) and iPex (NSK) - in different groups of human teeth by using radiography. The working lengths (WLs) of 100 root canals were determined electronically. The EAL to be used first was chosen randomly and a K-file was inserted into the root canal until the EAL display indicated the location of the apical constriction (0 mm). The K-file was fixed to the tooth and a periapical radiograph was taken using a radiographic film holder. The K-file was removed and the WL was measured. The same procedure was repeated using the other EAL. Radiographs were examined with the aid of a light-box with lens of ×4 magnification by two blinded experienced endodontists. The distance between the file tip and the root apex was recorded as follows: (A) +1 to 0 mm, (B) -0.1 to 0.5 mm, (C) -0.6 to 1 mm, (D) -1.1 to 1.5 mm, and (E) -1.6 mm or greater. For statistical purposes, these scores were divided into 2 subgroups according to the radiographic apex: acceptable (B, C, and D) and non-acceptable (A and E). Statistically significant differences were not found between the results of Apex and iPex in terms of acceptable and non-acceptable measurements (p>0.05) or in terms of the distance recorded from file tip and the radiographic apex (p>0.05). Apex and iPex EALs provided reliable measurements for WL determination for endodontic therapy.