Fracture incidence of WaveOne Gold files: a prospective clinical study.

AIM: This prospective clinical study evaluated the incidence of instrument fracture observed after single-file root canal treatment of molars using WaveOne Gold instruments. METHODOLOGY: Three standardized, experienced and calibrated specialists treated 750 maxillary and mandibular molars with curvatures less than 45° (2691 root canals) over a 12-month period. All the treatments were performed in a single session. A total of 1104 WaveOne Gold instruments were used, including 38 small, 750 primary, 228 medium and 88 large instruments. Intracanal procedures were performed according to the manufacturer's recommendations, and each instrument was used in a single clinical case. The instruments were examined after their removal from the canal, under an operating microscope at 8× magnification. RESULTS: No fractures were observed in any of the 1104 instruments used. CONCLUSIONS: No fractures of WaveOne Gold reciprocating instruments occurred during root canal preparations performed in maxillary and mandibular molars with curvatures less than 45° when used strictly according to the manufacturer's recommendations and applied in a single clinical case.

Evaluation of several instrumentation techniques and irrigation methods on the percentage of untouched canal wall and accumulated dentine debris in C-shaped canals.

AIM: To evaluate the effect of instrumentation using Reciproc Blue (RB; VDW, Munich, Germany) and XP-endo Shaper (XP-S; FKG Dentaire, La Chaux-deFonds, Switzerland) systems on the area of untouched canal wall (AUCW), accumulated hard-tissue debris (AHTD) and the efficacy of three irrigation protocols on percentage reductions (red%) of AHTD within C-shaped canals of mandibular molars. METHODOLOGY: Seventy mandibular molars with C-shaped canals were scanned, matched and assigned to two shaping groups (n = 35): RB and XP-S. Following instrumentation, specimens were triple-matched with respect to the amount of remaining debris and assigned to three irrigation subgroups (n = 10): syringe-and-needle irrigation (SNI), XP-endo Finisher (XP-F; FKG Dentaire) and passive ultrasonic irrigation (PUI). The AUCW% and AHTD% after instrumentation and the red% of AHTD after irrigation were calculated from micro-computed tomography. Data were analysed using comparisons for two groups (RB vs. XP-S) or multiple subgroups followed by pairwise comparison procedures (SNI vs. XP-F vs. PUI) at α = 0.05. RESULTS: For RB and XP-S, 33.04% and 30.45%, respectively, of the canal wall remained untouched (P > 0.05). For both groups, the apical third had larger AUCW% than the coronal third (P < 0.05). Instrumentation with RB left more debris (2.8%) than XP-S (1.1%) (P < 0.05). The PUI and XP-F subgroups had higher mean red% of AHTD than the SNI subgroup; the difference was significant for RB (P < 0.05) but not for XP-S. CONCLUSIONS: Both RB and XP-S systems were associated with similar AUCW after instrumenting C-shaped canals. RB left significantly greater levels of AHTD compared with XP-S. PUI and XP-F irrigation removed more debris than SNI when using the RB system.

Comparative accuracy of the Clearing Technique, CBCT and Micro-CT methods in studying the mesial root canal configuration of mandibular first molars.

AIMS: To compare the accuracy of the clearing technique and cone beam computed tomography (CBCT) in the assessment of root canal configurations using micro-computed tomography (micro-CT) imaging system as the reference standard. METHODOLOGY: Thirty-two mesial roots of mandibular first molars, selected on the basis of micro-CT scans (voxel size: 19.6 µm) and presenting several canal configurations, were evaluated using 2 CBCT scanners (voxels sizes: 120 µm and 150 µm) followed by the clearing technique. Two examiners analysed the data from each method and classified the anatomical configuration of the mesial canal according to Vertucci's system. Data were compared using Fisher's exact and chi-square tests. Reliability for each assessment was verified by the kappa test, and significance level was set at 5%. RESULTS: Kappa value indicated a high level of agreement between the examiners. Detection of type I configurations was significantly lower in cleared teeth (P < 0.05), whilst type II root canals were detected in all specimens by both tests (P > 0.05). In mesial roots with variable anatomical configurations, CBCT and the clearing method were significantly less accurate than the reference standard (P < 0.05). CONCLUSION: Within the tooth population studied, accuracy of identifying mesial root canal configuration was influenced greatly by the evaluation method and the type of anatomy. Detection of type I configurations in cleared teeth was significantly lower, whilst type II configurations were detected in all specimens by both methods. In mesial roots with variable anatomical configurations, neither CBCT nor clearing methods were accurate for detecting the actual root canal anatomy.

A comparison of four gutta-percha filling techniques in simulated C-shaped canals.

AIM: To compare four gutta-percha filling techniques in simulated C-shaped canals based on filling quality at three cross-sectional levels, filling time and the apical extrusion of gutta-percha. METHODOLOGY: Forty resin simulated C-shaped canals were constructed and filled using one of four techniques: cold lateral compaction (LC), ultrasonic compaction (UC), single cone with injectable gutta-percha (Obtura II(™) ) (IT) and core-carrier (Thermafil(®) ) (CC). Cross sections were made at 1 (L1), 3 (L3) and 6 (L6) mm from the canal terminus. Areas of gutta-percha, sealer and voids in each cross section were measured using an image analysis system. Data were analysed using a univariate general linear model and post hoc test (Dunnett's T3). Data on time taken to fill canals was evaluated using the Bonferroni post hoc test. RESULTS: CC had more gutta-percha and less sealer compared with IT at L1 (P < 0.05). LC had marginally significantly less gutta-percha than CC at this level (P = 0.049). At level 3 mm, significantly more gutta-percha and less sealer were present in IT compared with LC (P < 0.05). The techniques showed no difference in quality at L6. The time for LC (20.72 min) was three times longer than for both IT (6.11 min) and CC (6.67 min), whereas for UC (26.92 min), it was four times longer (P < 0.001). Finally, the four techniques were not different in the occurrence of apical extrusion of gutta-percha. CONCLUSIONS: The core-carrier technique was the most effective technique when assessed by gutta-percha area in this simulated C-shaped canal.

Micro-CT evaluation of C-shaped mandibular first premolars in a Brazilian subpopulation.

AIM: To describe morphometric aspects of the internal anatomy of C-shaped mandibular premolars from a Brazilian subpopulation using micro-CT analysis. METHODOLOGY: First mandibular premolars with radicular grooves (n = 123) were scanned using a micro-computed tomography system. After cross-section analysis, 83 specimens were identified with a C-shaped canal and selected for micro-CT analysis. Number and location of canals according to Vertucci's classification, distances between anatomic landmarks, occurrence of apical deltas, furcation canals, prevalence of C-shaped cross-sections at five levels as well as 2-dimensional analysis (Area, perimeter, roundness, aspect ratio, major and minor diameters) were performed for the more prevalent anatomical features. Data were compared statistically using Kruskal-Wallis tests (α = 0.05). RESULTS: The more prevalent anatomical types according to Vertucci's classification were Type I (13%), III (8%), V (37%) and VII (2%). Mean distances from the furcation to the cemento-enamel junction were in the range of 5.36-5.65 mm. Apical deltas and furcation canals were present in 36 (43%) and 27 (33%) specimens, respectively. C-shaped cross-sections were more prevalent at the middle (56%) and apical middle levels (81%). Overall, significant differences were found in the 2-dimensional analyses between single canals at the apical third and buccal and lingual canals of Vertucci's V classification (P < 0.05). CONCLUSIONS: In this Brazilian subpopulation, C-shaped canal configuration of the root canal system was found in 67% of extracted first mandibular premolars with radicular grooves. Vertucci's types I and V were the most prevalent anatomical variations. C-shaped cross-sections were more prevalent in the middle third, and the presence of apical deltas was the most common feature in the apical third.

Alteration in the inherent metallic and surface properties of nickel-titanium root canal instruments to enhance performance, durability and safety: a focused review.

The expanded use of nickel-titanium (NiTi) rotary instruments in root canal procedures has led to the development of a wide variety of shapes, designs and applications. Root canal anatomy has not changed, however, and the same challenges exist in both initial treatment and the revision of unacceptable treatment. These challenges include application with high levels of achievement and low to no levels of adverse effects, such as instrument fracture, root canal wall ledging, dentine wall perforation and so forth. To that end, many manufacturers have been seeking ways to alter the presently available and wide range of root canal instrument designs, with a focus on altering the surface of the alloy or altering the alloy microstructure with post-machining or post-twisting heat treatment. This focused review will address the impact that these modifications have had on instrument flexibility, resistance to cyclic fatigue and cutting efficiency.

Three-dimensional morphological analysis of C-shaped canals in mandibular first premolars in a Chinese population.

AIM: To investigate and compare the unique anatomical features and positioning of C-shaped canals in mandibular first premolars with and without radicular grooves in a Chinese population. METHODOLOGY: A total of 327 extracted mandibular first premolars including 146 with radicular grooves and 181 without radicular grooves from a Chinese population were scanned by µCT-50 or µCT-80. After reconstruction, canal systems were classified according to a modified Vertucci method and the anatomical features evaluated. The data were analysed by one-way anova test, Chi-square test and Fisher's exact test (P < 0.05). RESULTS: Of 146 mandibular first premolars with a radicular groove, 97 had C-shaped canals, the predominant anatomical canal type being Vb (P < 0.001), which was characterized by an oval canal in the coronal part and a semicolon or continuous C-shape beneath the groove. Of the 181 mandibular first premolars without a radicular groove, no C-shaped canal system was observed, and the percentage of Ia (97.8%) was significantly higher than those of other types (P < 0.001). CONCLUSION: In teeth from a Chinese population, mandibular first premolars with radicular grooves had a high incidence of C-shaped canal systems with anatomical variations along the root.

The efficacy of pre-operative oral medication of lornoxicam and diclofenac potassium on the success of inferior alveolar nerve block in patients with irreversible pulpitis: a double-blind, randomised controlled clinical trial.

AIM: To determine the effect of administration of pre-operative lornoxicam (LNX) or diclofenac potassium (DP) on the success of inferior alveolar nerve blocks (IANB) in patients with irreversible pulpitis in a double-blind randomised controlled trial. METHODOLOGY: One hundred and fourteen patients with irreversible pulpitis of a mandibular posterior tooth participated. Patients indicated their pain scores on a Heft Parker visual analogue scale, after which they were randomly divided into three groups (n = 38). The subjects received identical capsules containing 8 mg LNX, 50 mg DP or cellulose powder (placebo, PLAC), 1 h before administration of IANB with 2% lidocaine containing 1 : 200 000 epinephrine. Lip numbness was assessed after 15 min, following which the teeth were tested with cold spray and their responses (negative or positive) were recorded. Access cavities were then prepared and success of IANB was defined as the absence of pain during access preparation and root canal instrumentation. The data were analysed using chi-squared tests. RESULTS: The percentages of teeth giving a negative response to cold test were 42.8% (PLAC), 78.5% (LNX) and 67.8% (DP), with no significant differences amongst the groups (P > 0.05). The success rates for the IANB in descending order were 71.4% (LNX), 53.5% (DP) and 28.5 (PLAC). A significant (P < 0.001) difference was found between the LNX and the PLAC groups only. CONCLUSIONS: Pre-operative administration of LNX significantly improved the efficacy of IANB in patients with irreversible pulpitis, whilst the effect of pre-medication with DP was not significantly different from the PLAC.

Analysis of the gutta-percha filled area in C-shaped mandibular molars obturated with a modified MicroSeal technique.

AIM: To analyse the gutta-percha filled area of C-shaped molar teeth root filled with the modified MicroSeal technique with reference to the radiographic features and the C-shaped canal configuration. METHODOLOGY: Twenty-three mandibular second molar teeth with C-shaped roots were classified according to their radiographic features as: type I--merging, type II--symmetrical and type III--asymmetrical. The canals were root filled using a modified technique of the MicroSeal system. Horizontal sections at intervals of 600 mum were made 1 mm from the apex to the subpulpal floor level. The percentage of gutta-percha area from the apical, middle and coronal levels of the radiographic types was analysed using the Kruskal-Wallis test. Complementary analysis of the C-shaped canal configurations (C1, C2 and C3) determined from cross-sections from the apical third was performed in a similar way. RESULTS: No significant differences were found between the radiographic types in terms of the percentage of gutta-percha area at any level (P > 0.05): apical third, type I: 77.04%, II: 70.48% and III: 77.13%, middle third, type I: 95.72%, II: 93.17%, III: 91.13% and coronal level, type I: 98.30%, II: 98.25%, III: 97.14%. Overall, the percentage of the filling material was lower in the apical third (P < 0.05). No significant differences were found between the C-shaped canal configurations apically; C1: 72.64%, C2: 79.62%, C3: 73.51% (P > 0.05). CONCLUSIONS: The percentage of area filled with gutta-percha was similar in the three radiographic types and canal configuration categories of C-shaped molars. These results show the difficulty of achieving predictable filling of the root canal system when this anatomical variation exists. In general, the apical third was less completely filled.

Dislocation resistance of ProRoot Endo Sealer, a calcium silicate-based root canal sealer, from radicular dentine.

AIM: To examine the dislocation resistance of three root canal sealers from radicular dentine with and without immersion in a simulated body fluid (SBF), using a modified push-out test design that produced simulated canal spaces of uniform dimensions under identical cleaning and shaping conditions. METHODOLOGY: Sixty single-rooted caries-free human canine teeth were used. Standardized simulated canal spaces were created using 0.04 taper ProFile instruments along the coronal, middle and apical thirds of longitudinal tooth slabs. Following NaOCl/ethylenediamine tetra-acetic acid cleaning, the cavities were filled with ProRoot Endo Sealer, AH Plus Jet or Pulp Canal Sealer. After setting, half of the cavities were tested with a fibre-optic light-illuminated push-out testing device. The rest were immersed in SBF for 4 weeks before push-out evaluation. Failure modes were examined with stereomicroscopy and field emission (FE)-scanning electron microscopy. RESULTS: Location of the sealer-filled cavities did not affect push-out strengths. ProRoot Endo Sealer exhibited higher push-out strengths than the other two sealers particularly after SBF storage (P < 0.001). Failure modes were predominantly adhesive and mixed for Pulp Canal Sealer and AH Plus Jet, and predominantly cohesive for ProRoot Endo Sealer. Spherical amorphous calcium phosphate-like phases that spontaneously transformed into apatite-like phases were seen in the fractured specimens of ProRoot Endo Sealer after SBF storage. CONCLUSIONS: When tested in bulk without a main core, both 'sealer type' and 'SBF storage' were significant in affecting push-out results. The ProRoot Endo Sealer demonstrated the presence of spherical amorphous calcium phosphate-like phases and apatite-like phases (i.e. ex vivo bioactivity) after SBF storage.

Microscopic appearance and apical seal of root canals filled with gutta-percha and ProRoot Endo Sealer after immersion in a phosphate-containing fluid.

AIM: To investigate the sealing quality of ProRoot Endo Sealer, a calcium silicate-based sealer and its morphologic characteristics after immersion in a phosphate-containing fluid (PCF). METHODOLOGY: Single-rooted canals were filled with gutta-percha and either ProRoot Endo Sealer or two commercially available zinc oxide eugenol (ZOE)-based and epoxy resin-based sealers. The sealers were allowed to set for 6 days and the filled teeth were immersed in PCF for 24 h before fluid leakage evaluation. After initial leakage evaluation at the 7th day, each filled root was restored and reimmersed in PCF for 28 days before the second phase of leakage evaluation at 35 days. Cryofractured specimens of additional teeth filled with the three sealers were examined using scanning electron microscopy after immersion in PCF for the two periods. RESULTS: One-way repeated measures anova and Tukey test revealed significant differences between the ZOE-based sealer at 35 days and the calcium silicate-based sealer at 35 days (P < 0.001), and between the ZOE-based sealer at 7 days and the calcium silicate-based sealer at 35 days (P = 0.001). No difference was found between the epoxy resin-based sealer and the calcium silicate-based sealer after both storage periods. Cryofractured calcium silicate-based sealer specimens demonstrated apatite-like crystalline deposits along the apical and middle thirds of the canal walls via transformation from amorphous calcium phosphate-like precursors. CONCLUSIONS: ProRoot Endo Sealer is comparable in sealing quality to the epoxy resin-based sealer and seals better than the ZOE-based sealer after immersion in PCF. The calcium silicate-based sealer also demonstrates ex vivo bioactivity when it comes into contact with phosphate ions.

Prevalence, location, and patency of accessory canals in the furcation region of permanent molars.

One hundred and two extracted permanent molars were debrided in 3% H2O2, sealed at the apex, and placed in a vacuum chamber. Safranin dye was introduced into the teeth that were placed in a vacuum of 525 mm of Hg. Observations were made of the external root surface to determine any staining due to patent accessory canals. Accessory canals were demonstrated in the "furcation region" in 28.4% of the total sample; 29.4% in mandibular molars, and 27.4% in maxillary molars. Of the total sample 25.5% exhibited canals in the "furcation" only, while 10.2% exhibited canals on the lateral root surface. Communication between the pulp chamber and the external surface was noted via dentinal tubules, especially when the cementum was denuded. The salient biologic and pathologic ramification of these aberrant canals were discussed along with the need to establish a differential diagnosis in order to determine the proper sequence of treatment should pulpal-periodontal disease exist.

Survey of endodontic retreatment methods used to remove intraradicular posts.

A survey was conducted to determine the frequency and popularity of contemporary methods used in endodontic retreatment to remove intraradicular posts. Opinions and rationales were also sought for the choice of surgical management instead of nonsurgical retreatment. A questionnaire was sent to 571 active Diplomates of the American Board of Endodontics with 324 members responding (56.7%). Hand instruments, such as hemostats or special forceps, were the most commonly used, often in conjunction with ultrasonic or sonic vibration to loosen the post or break down the cement interface. A wide range of rationales was identified for the use of surgical retreatment methods, with failure to remove the post after reasonable nonsurgical efforts being the most often cited.

Revisiting the post puller.

The removal of an intraradicular post is frequently part of retreatment and the fabrication of a new coronal restoration. This article highlights the use of a post puller for safe and effective removal of an intraradicular post in conjunction with retreatment.

The dental hygienist as a co-therapist in the endodontic practice.

This paper explores the potential contributions to patients, the practice, the endodontist, and the dental hygienist that may be realized by the employment of one or more dental hygienists to serve as endodontic co-therapists in the delivery of endodontic treatment. An endodontic co-therapist is an individual who participates with the endodontist in the assessment, planning, implementation, and evaluation of treatment much like the periodontal co-therapist relationship that exists between periodontists and dental hygienists. Dental hygienists are ideal individuals for this role because of their education in basic, clinical, and behavioral sciences. Suggestions are provided for which services could be delegated by the endodontist to the dental hygienist during each phase of care. Advantages of this contemporary approach to the delivery of endodontic treatment are also addressed.

Effects of calcium hydroxide and transforming [correction of tumor] growth factor-beta on collagen synthesis in subcultures I and V of osteoblasts.

Collagen protein synthesis by osteoblasts is influenced by transforming growth factor-beta (TGF-beta 1) and is essential to bone formation. The effectiveness of TGF-beta 1 depends on efficient delivery of the growth factor to target cells, adequate binding to cell surface receptors, and an optimum environment for promotion of collagen synthesis. The effects of calcium hydroxide (Ca(OH)2), TGF-beta 1, and Ca(OH)2/TGF-beta 1 co-administration on total protein, collagen protein, and noncollagen protein synthesis by early (subculture I) and late (subculture V) osteoblast cultures were tested. TGF-beta 1 significantly increased all protein synthesis in subculture I osteoblasts (p = 0.001; p < 0.001; p = 0.019). Ca(OH)2/TGF-beta 1 co-administration significantly increased total protein and collagen protein levels in subculture I osteoblasts as well (p = 0.048; p = 0.012). TGF-beta 1 increased total protein and collagen protein synthesis significantly in subculture V cells (p = 0.025; p = 0.01). These data indicate that co-administration of Ca(OH)2 and TGF-beta 1 enhances collagen synthesis by osteoblasts and may have implications for the clinical setting.

In vivo evaluation of root canal sealer distribution.

The effectiveness of sealer placement and its distribution in the prepared root canal system by an energized ultrasonic file was evaluated in vivo. One hundred patients had sealer placed into prepared root canals with either the master gutta-percha cone or an ultrasonic file. Before placement of sealer with the file, canals were irrigated, debrided, and flushed with water for 10 s and an energized #20 ultrasonic file at 1.0 mm from the working length. Canals were obturated with gutta-percha using lateral condensation, and evaluations were based on the presence or absence of sealer-filled accessory canals. Chi-square analysis showed that a statistically significant difference existed in the number of radiographically visible accessory canals filled when the ultrasonic file was used to place the sealer.

Histologic assessment of healing after the use of a bioresorbable membrane in the management of buccal bone loss concomitant with periradicular surgery.

Histological and morphometric assessment of periradicular wound healing was made after the use of a bioresorbable membrane over a buccal dehiscence. The third and fourth premolar teeth of nine dogs were resected and buccal defects created. Teeth were assigned randomly to the membrane or control group. One tooth in each quadrant received a membrane, covering both roots. The other tooth received no further treatment and served as a control. The animals were killed and specimens were assessed at two time periods: 9 wk and 27 wk. The 27-wk membrane group exhibited significantly more (p = 0.004) connective tissue height than the control group or either of the 9-wk groups. The amount of regenerated alveolar bone was significantly greater for the 27-wk membrane group than for the control (p = 0.001) and 9-wk groups. Mean junctional epithelium measurements were significantly greater (p = 0.012) for the control. The use of a bioresorbable membrane enhances bone regeneration when a buccal defect exists at the time of periradicular surgery.