J Bagh College Dentistry Vol. 29(3), September 2017 In Vitro The Effect Restorative Dentistry 17 In Vitro The Effect of Canals Instrumented With Three Rotary Ni-Ti Systems on The Dislocation Resistanceo Guttafusion® Versus Single Cone Obturation Technique Rafal S. Ameen, B.D.S. (1) Raghad A. Al Hashimi, B.D.S., M.Sc., Ph.D. (London, UK) (2) ABSTRACT Background: Complete seal of the root canal system following its chemo-mechanical debridement plays a pivotal role for achieving successful endodontic treatment. This can be established by reducing the gaps between the core filling material and root canal wall. Aim: To assess and compare the dislocation resistance of root canals obturated with GuttaFusion® and TotalFill BC sealer versus single cone obturation technique and TotalFill BC sealer after instrumentation of the canals with WaveOne, ProTaper Next and ProTaper Universal system. Material and Method: Sixty extracted human permanent mandibular premolars were conducted in the current study. The teeth were decorated and left the root with 15mm length; the roots were divided randomly into three main groups, twenty roots in each group. The roots were instrumented with different rotary systems using crown down technique according to the groups: (Group I) was instrumented with WaveOne files. (Group II) was instrumented with ProTaper Next system and (Group III) was instrumented with ProTaper Universal system. For each group the same irrigation regimen was used, 3 mL of 5.25% sodium hypochlorite and 3 mL of 17% EDTA to remove the smear layer. Then, Group I was also subdivided randomly into two subgroups of ten samples each, (Group I A) obturated with single cone gutta-percha and (Group I B) filled with GuttaFusion®. Group II was divided into (Group II A) obturated with single cone gutta-percha and (Group II B) filled with GuttaFusion®. Group III was divided into (Group III A) obturated with single cone gutta-percha and (Group III B) obturated with GuttaFusion®. In the present study, TotalFill BC sealer was used for all the tested groups. Then, the roots were embedded in clear acrylic resin and each root sectioned into three sections of 2mm thick (apical, middle and coronal). The push-out bond strength values represented by (MPa) unit was calculated by dividing the load on the surface area and the last was measured in collaboration with AutoCAD system software program. Failure mode analysis was carried out to examine the type of failure in each sample by using a stereomicroscope. Results: The results showed highly significant differences among the main groups that instrumented with different rotary systems (WaveOne, ProTaper Next and ProTaper Universal system). There were highly significant differences between the two obturation techniques of the subgroups (single cone gutta-percha versus GuttaFusion®). However; Gutta-Fusion® showed highest bond strength value than single cone obturation technique. The coronal third slices of all groups showed highest value of bond strength in comparison to the middle thirds and apical thirds. In the meantime, the middle third slices showed bond strength higher than that of the apical thirds for all groups. Statistical analysis was performed by using two way ANOVA and LSD tests. Conclusions: The instrumentation techniques and the obturation materials significantly affected the push-out bond strength values of obturation system. The highest value was appointed in root canals instrumented with ProTaper Universal System; obturated with GuttaFusion® and BC sealer, whereas, the lowest bond strength was appeared at canals instrumented with ProTaper Next; obturated with single cone gutta-percha and BC sealer. Keywords: BC sealer, GuttaFusion®, push-out bond, WaveOne system, ProTaper Next, ProTaper Universal. (J Bagh Coll Dentistry 2017; 29(3):17-25) INTRODUCTION Three-dimensional seal of the root canal space is one of the fundamental goals of successful endodontic treatment, therefore various obturation materials and techniques were developed to fill root canal system and obliterate any voids or space within it in order to prevent reinfection of the tooth with bacteria and their by-product (1). In this study, three rotary systems were employed for preparation of the root canals including, WaveOne (reciprocation motion), ProTaper Next (continuous rotation) and ProTaper Universal (continuous rotation) due to its improved cutting efficiency and safety in comparison with stainless steel files (2). (1) Master Student, Department of Conservative Dentistry, College of Dentistry, University of Baghdad. (2) Assistant Professor, Department of Conservative Dentistry, College of Dentistry, University of Baghdad. In addition, TotalFill BC sealer was used for all the experimental groups since; it has been reported that the hydrophilic sealer uses moisture of the root space for completing setting reaction (3). Moreover, this sealer was adapted perfectly to dentine and formation of a chemical bond with inorganic phase of dentine (4). In this study, half of the tested groups were obturated using single cone technique, which uses larger master cone that closely match the geometry of the last rotary NiTi files that used during instrumentation; thereby it is facilitating the root canal filling (5). Nevertheless, gutta- percha is not adhered to the root canal wall compromising the concept of three-dimensional seal, therefore; a nother obturation techniques have been introduced over the past decade to improve the seal of the root canal system. J Bagh College Dentistry Vol. 29(3), September 2017 In Vitro The Effect Restorative Dentistry 18 However, a three-dimensional seal is important for reducing diseases associated with root canal treatment (6). Thus, carrier based gutta-percha technique is an effective method for obturation of the rest prepared canal with a GuttaFusion® in which the core made from chains of crosslinked polymer of gutta-percha that coated with flowale gutta percha without need for metal or plastic core. The benefit of carrier is to condense gutta-percha which is heated by special devise to enhance its flow into the canal (7). So, half of the groups were obturated with GuttaFusion®. This study was designed to compare the push-out bond strength exhibited by root fillings performed with either GuttaFusion® and BC sealer or single cone gutta-percha and BC sealer after instrumentation of root canals with either WaveOne (WO) (reciprocating file) or ProTaper Next and Pro Taper Universal (rotation files). The null hypothesis stated that there is no effect of either instrumentation technique or obturation method on the push-out bond strength value. MATERIAL AND METHOD Sample selection Sixty extracted human mandibular permanent premolars were selected from different health centers according to specific criteria. The age (18- 24 years) while the status of the pulp, gender and extraction reason were not being considered and the criteria for selection of teeth included the following: straight root canal, mature, patent, centrally located apical foramen and roots devoid of any resorptions (8, 9). Sample preparation After extraction, all the teeth were stored in distilled water. Afterward, sharp periodontal curette was used to remove remnants of soft tissue on the root surface and magnifying eye lens (10X) was used to verify the root surfaces and any visible cracks or fractures saw by using a light cure device (10). Then, the teeth were decorated and left the root with 15mm length using diamond cut off saw with the use of the water coolant to minimize the formation of smear Fig. 1 (11). Then a size 10 k- file (Dentsply, Maillefer, Switzerland) was used to ensure straight canal, patency and central position of apical foramina. The exact location of the apical foramen was determined by advancing the size 10 k-file into the canal until it was visualized at the apical foramen (10). Then Silicon rubber base impression material (heavy-body) was mixed according to manufacturer’s instructions (base and catalyst) and inserted inside the plastic containers, then the root was inserted in center of the heavy body to facilitate handling of the roots during instrumentation and obturation procedure (10). Study design The selected teeth were randomly divided into the following 6 subgroups (n = 60): 1. Group I A: WaveOne instrumentation (Dentsply, Maillefer, Switzerland), followed by obturation using single cone gutta-percha (Dentsply, Maillefer, Switzerland) and TotalFill BC sealer (Brasseler, Savannah, USA). 2. Group I B: WaveOne instrumentation (Dentsply, Maillefer, Switzerland), followed by obturation using GuttaFusion® (VDW, Germany) and TotalFill BC sealer (Brasseler, Savannah, USA). 3. Group II A: ProTaper Next instrumentation (Dentsply, Maillefer, Switzerland) followed by obturation using single cone gutta-percha (Dentsply, Maillefer, Switzerland) and TotalFill BC sealer (Brasseler, Savannah, USA). 4. Group II B: ProTaper Next instrumentation (Dentsply, Maillefer, Switzerland) followed by obturation using GuttaFusion® (VDW, Germany) and TotalFill BC sealer (Brasseler, Savannah, USA). 5. Group III A: ProTaper Universal instrumentation (Dentsply, Maillefer, Switzerland) followed by obturation using single cone gutta-percha (Dentsply, Maillefer, Switzerland) and TotalFill BC sealer (Brasseler, Savannah, USA). 6. Group III B: ProTaper Universal instrumentation (Dentsply, Maillefer, Switzerland) followed by obturation using GuttaFusion® (VDW, Germany) and TotalFill BC sealer (Brasseler, Savannah, USA). Root canal instrumentation 1. Group I (A and B) WaveOne System instrumentation: (20sample) Firstly, WaveOne primary file was connected to endo-motor (smart X) (Densply, Maillefer Switzerland) to produce glide path for large WO file (black) which is 40\08 (12). The irrigation regimen which used for all groups was 3 mL of 5.25% NaOCl (Cerkamed, Poland). The smear layer was removed with 3 mL of 17% aqueous EDTA solution (Dental Produits Dentaires SA, Switzerland) for one minute and followed with a final flush with 3 ml of distilled water (9). 2. Group II (A and B) ProTaper Next instrumentation: (20sample) The endo-motor X-smart (Densply, Maillefer Switzerland) was worked at speed of 300 rpm and torque of 2.0 Ncm with X1 20/04. Then, X2 J Bagh College Dentistry Vol. 29(3), September 2017 In Vitro The Effect Restorative Dentistry 19 25/06, X3 30/07, were used in same manner to provide glide path for X4 40/06 (12). 3. Groups III (A and B) ProTaper Universal instrumentation (20sample) Firstly, the canal was instrumented with (S1), 17/04 with endo-motor X-smart (Densply, Maillefer Switzerland) which was operated at speed of 250 rpm and torque of 3.0 Ncm then, (S2) 20/02 was used with speed of 250 rpm and torque of 1.0 Ncm, while F1 20\ 07 was worked at speed of 250 rpm and torque of 1.5 Ncm while F2 25\08, F3 30\09, F4 40\06 were used respectively at constant speed of 250 rpm and constant torque of 2.0 Ncm (12). Samples obturation: I.Group I A, II A, III A obturation with single cone technique: The canal was dried with a corresponding paper point size # 40 (Dentsply, Maillefer, Switzerland).At this time, the canal was ready for obturation with single cone obturation material(Dentsply, Maillefer, Switzerland) and a TotalFill sealer (Brasseler, Savannah, USA) that dispensed through its auto mix syringe tip into the coronal third of the root canal according to the manufacturer's instructions (8), afterwards a single cone gutta-perch size #40 was slowly inserted to full working length of the canal. For these groups (IA, IIA and III A) a heated plugger (Medesey, Italy) was used to remove the access gutta-percha out of the orifice of the canal (13). I. Group I B, II B, III B obturation with GuttaFusion®: These groups were obturated with GuttaFusion® after drying the canal with a corresponding paper point size #40(Dentsply, Maillefer, Switzerland) Fig. 2. Next, TotalFill sealer (Brasseler, Savannah, USA) was dispensed through its auto- mix syringe tip into the coronal third of the root canal according to the manufacturer's instructions and hand file size #15 coated with a thin layer of BC sealer dispensed on glass slab, then the file was lightly coat the canal wall with existing sealer. Afterward, the holder of GuttaFusion® oven was raised to hold the GuttaFusion® obturator size # 40 then pushed down to start thermoplasticizing the obturator Fig. 3. Then the oven gave visual and acoustic warning signals which indicated that the obturator was ready to be used. Afterward, the obturator was took out from the obturater holders which can be released easily by pushing it down and placed within the canal to the full working length. Afterward, the obturator handle was bending to right and left until separation took place and then, core material condensated with plugger (14). Then, the root was radiographed within their silicon rubber base mold to ensure adequate obturation, then moistened gauze with normal saline was wrapped each group. Afterward, all samples were stored in an incubator for 7 days at 100% humidity and 37 OC to ensure complete setting of the sealer (15). Teeth sectioning The samples were embedded in clear orthodontic resin after the period of storage (16). Firstly, a cylinder mold with four holes was prepared from silicon material (OOMOO® Smooth-On, East Texas), each hole has 25 mm depth and 10 mm width .In general, the width of the cylinder was 6 cm while, the depth of it was 25mm. The root was inserted in the base (center) of each hole with the aid of dental surveyor; however, the coronal surface of the root was fixed with sticky wax to the dental surveyor to ensure accurate and central placement of the root and perpendicular sectioning to the long axis of the roots. As recommended by the manufacturers, the acrylic was prepared by mixing powder and liquid. Evaporation of monomer was prevented by covering the jar. Afterward, the material was left for few minutes to reach the workable stage. Afterward, the freshly prepared cold cure acrylic paste was loaded in cylinder hole and pushed with spatula to ensure that the acrylic sample was devoid from any void with complete coverage of the root with acrylic Fig. 4 (17). Then, after complete setting of the acrylic sample; it was removed from the cylinder hole and each sample was sectioned horizontally into 2 mm thick slices at each of the three-thirds (coronal, middle and apical) of the root using a diamond disc with continuous water flow to minimize smearing Fig. 5 (11). Push-out test After measuring of the apical side diameter of the slice, the cylindrical metal punch tip (either 0.4, 0.6 or 0.8 mm in diameter) was selected to cover as much as possible of the root filling, yet avoiding any contact with the canal walls (18). After placement of specimens on base, the load was applied by the punch in apico-coronal direction using a universal testing machine at speed 0.5mm/min Fig. 6. The push-out bond strength value represented by (MPa) unit was calculated by dividing the load in Newton on the surface area (mm2) that calculated in collaboration with Auto CAD system software program (19). Afterward, a stereomicroscope examined the root canal wall of each samples at 25X magnification to determine the failure mode (20). Bond strength MPa = Debonding force (N)/ interfacial area mm2 J Bagh College Dentistry Vol. 29(3), September 2017 In Vitro The Effect Restorative Dentistry 20 The interfacial area (mm2) was calculated by 0.5(circumference of coronal aspect + circumference of apical aspect) * thickness (21). Analysis of failure modes Stereomicroscope (Hamilton, Altay) was used to inspect a slice at 25x magnification to determine the failure mode. Each sample was evaluated and placed into one of three failure modes (22) Type I: adhesive failure, either at the sealer-dentin (S/D) or between the sealer-core (S/C) interfaces, Type II: cohesive failure, within the filling material (sealer or core material), Type III: mixed failure, which contains both adhesive and cohesive failures. Figure 1: Length of tooth was measured with a digital caliper Figure 2: GuttaFusion® gutta-percha size # 40 & TotalFill sealer Figure 3: GuttaFusion® oven with GuttaFusion® after pressed its handle Figure 4: Central placement of the root with a cylinder hole Figure 5: a. Sectioning of the specimen, b. the specimen measured with digital caliper Figure 6: Universal testing machine RESULTS Mean values and standard deviation for all groups are presented in (Table 1). Analysis of variance (ANOVA) test was performed and showed that the highest and the lowest mean values of push-out bond strength were seen in (Group III B) at coronal third of root canal that instrumented with PTU system and filled with GuttaFusion® (5.017 MPa) and (Group II A) at apical level of canal filled with single cone gutta- percha after its instrumented with PTN (1.645 MPa) respectively Fig. 7. Other mean values of the study groups were swing between these values. a b J Bagh College Dentistry Vol. 29(3), September 2017 In Vitro The Effect Restorative Dentistry 21 Analysis of variance (ANOVA) test was preformed to compare between the obturation systems at each level and to identify if there is any statistically significant differences (regarding push-out bond strength) between two obturation systems within each level. Highly significant differences (p≤0.01) were found at all levels and the results showed the followings: 1. ANOVA test showed that among each site, there is highly significant effect of Group, Subgroup and interaction effect of Group* Subgroup on the variability of push-out bond strength with strong Coefficient of determination was found in the coronal site. 2. It was found at each site, ProTaper Universal system has the highest mean of push-out bond strength followed by WaveOne system. While, ProTaper Next system showed the lowest push-out bond strength with highly significant difference among them (regarding instrumentation techniques). 3. There was a highly significant difference of subgroups that obturated with GuttaFusion® than single cone obturation material at all level regardless the instrumentation techniques. However, Group I A (WO instrumentation, single cone obturation) showed highly significant difference than Group II A (PTN instrumentation, single cone obturation). While Group I A (WO instrumentation, single cone obturation) showed no significant difference than Group III A (PTU instrumentation, single cone obturation). While, Group I B(WO instrumentation, GuttaFusion® obturation) was showed no significant difference than Group II B (PTN instrumentation, GuttaFusion® obturation). While Group III B (PTU instrumentation, GuttaFusion® obturation) showed a highly significant difference than Group I B and Group II B Table 12. 4. There was a highly significant difference between all levels within all groups. The least significance difference test (LSD) was performed to evaluate the significant differences between each obturation system at each level and showed that: at each site and each Subgroup; there is highly significant difference between Groups except between (WO and PTU instrumentation with single cone obturation technique) and (WO and PTN instrumentation with GutaFusion® obturation) however, the result was found to be statistically not significant. The coronal third slices of the groups showed a highest value of bond strength in comparison to the middle thirds and apical thirds. In the meantime, the middle third slices showed bond strength higher than the apical thirds for all groups (Table 3) (Fig. 7). Figure 7: The mean value of push-out bond strength of two obturation systems The failure mode of the samples is presented in (Table 4). In this study the predominant mode of failure for canal instrumented with different rotary system (WO, PTN, PTU system and obturated with single cone gutta percha) was adhesive failure mainly at dentine / sealer interface. In addition the same groups showed fewer mixed failures followed by cohesive failure mainly within sealer when compared to the other techniques. However, the predominant mode of failure for canal instrumented with previous rotary systems and obturated with Gutta-Fusion® was mixed failure followed by cohesive failures mainly within gutta-percha and then adhesive failure was less frequent at all the sections of all subgroups that obturated with GuttaFusion®. J Bagh College Dentistry Vol. 29(3), September 2017 In Vitro The Effect Restorative Dentistry 22 Table 1: Descriptive statistics of push-out bond strength (Mean, ±SD, Max, Min) of tooth sites by groups and subgroups. Site Group Subgroup Single cone (A) GuttaFusion® (B) Total Min. Max. Mean ±SD Min. Max. Mean ±SD Min. Max. Mean ±SD Apical WO 1.87 2.80 2.46 0.30 3.30 4.26 3.61 0.29 1.87 4.26 3.03 .66 PTN 1.23 2.09 1.65 0.33 3.19 4.06 3.47 0.28 1.23 4.06 2.56 .98 PTU 1.74 2.65 2.22 0.33 4.22 5.20 4.51 0.30 1.74 5.20 3.36 1.21 Total 1.23 2.80 2.11 0.47 3.19 5.20 3.86 0.55 1.23 5.20 2.98 1.02 Middle WO 2.32 3.24 2.65 0.29 3.45 4.37 3.94 0.34 2.32 4.37 3.30 .73 PTN 1.46 2.29 1.88 0.31 3.36 4.31 3.78 0.34 1.46 4.31 2.83 1.03 PTU 2.00 2.96 2.40 0.36 4.46 5.37 4.84 0.30 2.00 5.37 3.62 1.29 Total 1.46 3.24 2.31 0.45 3.36 5.37 4.19 0.57 1.46 5.37 3.25 1.07 Coronal WO 2.54 3.28 2.82 0.28 3.55 4.40 4.02 0.29 2.54 4.40 3.42 .68 PTN 1.56 2.36 1.96 0.27 3.75 4.38 4.00 0.22 1.56 4.38 2.98 1.07 PTU 2.25 3.14 2.68 0.30 4.55 5.35 5.02 0.29 2.25 5.35 3.85 1.23 Total 1.56 3.28 2.49 0.47 3.55 5.35 4.35 0.55 1.56 5.35 3.42 1.07 Total WO 1.87 3.28 2.64 0.32 3.30 4.40 3.86 0.35 1.87 4.40 3.25 .70 PTN 1.23 2.36 1.83 0.32 3.19 4.38 3.75 0.35 1.23 4.38 2.79 1.03 PTU 1.74 3.14 2.44 0.37 4.22 5.37 4.79 0.36 1.74 5.37 3.61 1.24 Total 1.23 3.28 2.30 0.48 3.19 5.37 4.13 0.58 1.23 5.37 3.22 1.06 Table 2: Push-out bond strength variability of subgroups in each group by site by using two ways ANOVA Site Group Subgroup F Sig. Single cone GuttaFusion® Mean SE Mean SE Apical Wave one 2.455 .097 3.609 .097 70.872 .000 Protaper Next 1.645 .097 3.471 .097 177.445 .000 ProTaper Universal 2.220 .097 4.508 .097 278.595 .000 Middle Wave one 2.654 .102 3.940 .102 79.571 .000 Protaper Next 1.879 .102 3.781 .102 174.057 .000 ProTaper Universal 2.404 .102 4.837 .102 284.810 .000 Coronal Wave one 2.824 .087 4.022 .087 94.152 .000 Protaper Next 1.959 .087 3.999 .087 273.008 .000 ProTaper Universal 2.682 .087 5.017 .087 357.675 .000 Df=1. Table 3: LSD tests for push out bond strength among groups by subgroups at three sites Site Subgroup Group Group Sig. Apical Single cone WaveOne ProTaper Next .000 ProTaper Universal .092 ProTaper Next ProTaper Universal .000 GuttaFusion® WaveOne ProTaper Next .319 ProTaper Universal .000 ProTaper Next ProTaper Universal .000 Middle Single cone WaveOne ProTaper Next .000 ProTaper Universal .089 ProTaper Next ProTaper Universal .001 Gutta Fusion® WaveOne ProTaper Next .275 ProTaper Universal .000 ProTaper Next ProTaper Universal .000 Coronal Single cone WaveOne ProTaper Next .000 ProTaper Universal .255 ProTaper Next ProTaper Universal .000 Gutta Fusion® WaveOne ProTaper Next .853 ProTaper Universal .000 ProTaper Next ProTaper Universal .000 J Bagh College Dentistry Vol. 29(3), September 2017 In Vitro The Effect Restorative Dentistry 23 Table 4: failure mode for different subgroups Groups Adhesive Cohesive Mixed Group I A 57% 20% 23% Group II A 73% 5% 22% Group III A 70% 10% 20% Group I B 16% 21% 63% Group II B 26% 30% 44% Group III B 13% 30% 57% DISCUSSION Successful endodontic treatment is depending on the adhesion of obturation material to the root canal wall which is advantageous for two reasons. First, it must remove any void that permit fluid leakage between core material and dentine in static situation and the second reason is enabling obturation material to resist its dislodgement during subsequent manipulation in dynamic situations (23).The null hypothesis was rejected since both the instrumentation technique and obturation method was affecting the push-out bond strength. Amara et al in 2012 stated that push-out test is popular method for measuring the effectiveness of adhesion between dentine wall and intra-canal material (24). There was a highly significant difference between Group I, II, III (B) that obturated with carrier based obturation materials (Gutta- Fusion®) and Group I, II, III (A)(single cone obturation technique). An explanation for these results could be attributed to the decreased sealing ability of obturation materials when the thickness of sealer is increased regardless of the instrumentation technique. Initially, single cone obturation technique consists of placement of master cone obturation material that matched the last taper and size of file used in instrumentation (25). It was found that Group I A (canal instrumented with WO, single cone obturation) showed higher push out bond strength value than Group II A (PTN instrumentation and single cone obturation). An explanation for that taper of master large file (WO) is 08 and this is different from taper of PTN that 06. This led to enlargement of the apical third (especially the last 3 mm) of root canals to an 8% taper which is necessary for irrigation displacement and is enhancing a better sealing ability and long-term success for root canal obturations (26). This agree with Wu who found that reciprocation has better performance than continuous movements (Wu etal., 2000) (27) and (De-Deus et al., 2013) (18). Thus, the results disagreed with (Pawer et al., 2016) (9). While, Group I A (that instrumented with WO and single cone obturation) showed no significant differences with Group III A (instrumented with PTU, single cone obturation). This might be due to absence of a significant difference with 0.06 and 0.08 final taper (26).While, Group III A (PTU instrumentation with single cone obturation) showed highly significant differences than Group II A (PTN instrumentation and single cone obturation). Thus result might be related to difference in cross section or mode of rotation since, PTU has a convex triangle cross-section and symmetric rotation while, PTN has a patented, off-centred rectangular cross-section and asymmetric ‘Swaggering’ rotation (28). This result disagrees with (Li et al., 2014b) who indicated that the ProTaper Next is more efficient in cleaning and shaping the canal more than ProTaper Universal (29). Moreover, Group III B (canal instrumented with PTU, GuttaFusion® obturation) showed highly significant difference compared with Group I B and II B (canal instrumented with WO and PTN, GuttaFusion® obturation). Thus might be due to using of multiple files in some cases to shape and finish the canal completely resulting in more cleaned canal (30). In contrast, there was no significant difference between group I B and II B (canal instrumented with WO and PTN and obturated with GuttaFusion®) as in previous study on the shaping ability of rotary instrument; it was found that there were no significant differences between ProTaper Next and the WaveOne (31). Thus agreed with (Zogheib et al., 2012) (26). Independent of the preparation technique and obturation material, the coronal third showed the highest value of bond strength than the middle third. The apical third showed the lowest value of bond strength due to differences in the internal anatomy of each level of the root canal (32). This disagreed with (Babb et al., 2009) (33). After that, each slice was examined under stereomicroscope X 25 to determine the failure mode. In general, the predominant failure mode for canal instrumented with different rotary system (WO, PTN and PTU) and obturated with single cone gutta-percha was adhesive failure mainly at dentine / sealer interface. This may be related to the high amount of sealer relative to J Bagh College Dentistry Vol. 29(3), September 2017 In Vitro The Effect Restorative Dentistry 24 cone volume since, the sealer was not compacted against the root canal wall resulting in void that might be facilitate the separation of sealer from dentine surface (34).In addition the same groups showed fewer mixed failures followed by cohesive failure mainly within sealer when compared to the other techniques. 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Annali di Stomatologia 2014; 5(3): 91-7. الخالصة مختلفة استخدمت تقنيات ارتباط ختم ثالثي األبعاد لنظام قناة الجذرهو أحد األهداف األساسية للمعالجة اللبية. وقد أجريت هذه الدراسة لتقييم قوة الدفع للخارج لقوة WaveOne, ProTaper Next, ProTaperلختم القنوات الجذرية التي تم تحضيرها باستخدام ثالثة أنظمة دواره مصنوعة من النيكل والتيتانيوم والتي تتضمن Universal)) يسية، كان هناك عشرون ئئي إلى ثالث مجموعات ربشكل عشوا ملم. ثم قسمت الجذور51ستين جذرمقلوع من الضواحك السفلية تم قطعه و ترك الجذر مع طول WaveOneيسية األولى مع ئيسية، والتي تم تحضيرها باستخدام انظمه دوارة مختلفة وفقا للمجموعات: تم تحضيرأسنان المجموعة الرئجذر في كل مجموعة ر لكل . ProTaper Universal يسية األخيرة فقد حضرت باستخدامئاما المجموعة الر ProTaper Next يسية الثانية تم تحضيرها باستخدامئوالمجموعة الر لمدة دقيقة واحدة ثم EDTA ٪51مل من 3ثم يتم غسلها ب %1..1مل من هايبوكلورات الصوديوم بتركيز 3مجموعة تم استخدام نفس نظام الغسل باستخدام .مل من الماء المقطر 3تغسل القنوات ب شكل عشوائي إلى مجموعتين فرعيتين لكل منهما عشرة عينات ، وتمالء المجموعة الفرعية االولى مع تقنية المخروط االحادي بعد ذلك تقسم المجموعة األولى ب وأيضا قسمت المجموعة الثانية إلى مجموعتين فرعيتين، وتمالء واحدة مع تقنية المخروط االحادي ، بينما GuttaFusion ®وتمأل المجموعة الفرعية الثانية مع . ثم تقسم المجموعة الثالثة عشوائيا إلى مجموعتين فرعيتين. واحدة تمالء مع تقنية المخروط االحادي و GuttaFusion ®ء المجموعة الفرعية الثانية مع تمال GuttaFusion .®االخرى تمالء مع ملم )القمي، .فة وكل جذر قطعت منه ثالثة اجزاء ذات سمك بعد ذلك، وضعت الجذور في الحاضنة لمدة سبعة أيام، ثم صبت الجذورفي مادة االكريليك الشفا ملم | دقيقة. تم احتساب 5.1العنقي باستخدام جهاز اختبار عالمي بسرعة -العنقي(وتثبت هذه العينات على قاعدة و يسلط عليها الحمل في االتجاه القمي و الوسطي ميغاباسكال عن طريق قسمة قوة الحمل على المساحة التي يتم احتسابها باستخدام اعلى قوة ارتباط لمادة الحشوة قبل ازاحتها التي تقاس بوحدة (.(AutoCADبرنامج ,WaveOne, ProTaper Next) يسية التي حضرت مع انظمة دوارة مختلفةئبين المجموعات الر جداتم إجراء التحليل اإلحصائي وأظهرت النتائج اختالف كبير ProTaper Universal) هناك اختالفات كبيرة جدا بين التقنيتين المستخدمة لمأل قنوات الجذورالمجموعات الفرعية )مخروط احادي ، وكانت اعلى لقوة ارتباط حشوة الجذر من الجزء الوسطي وأظهر هذا األخير قيمة عالية لقوة ( و بالنسبة الجزاء الجذر فقد اظهر الجزءالعنقي قيمةGuttaFusion®مقابل .ذرمن الجزء القميارتباط حشوة الج https://www.ncbi.nlm.nih.gov/pubmed/?term=Ozsu%20D%5BAuthor%5D&cauthor=true&cauthor_uid=25512732 https://www.ncbi.nlm.nih.gov/pubmed/?term=Karatas%20E%5BAuthor%5D&cauthor=true&cauthor_uid=25512732 https://www.ncbi.nlm.nih.gov/pubmed/?term=Arslan%20H%5BAuthor%5D&cauthor=true&cauthor_uid=25512732 https://www.ncbi.nlm.nih.gov/pubmed/?term=Topcu%20MC%5BAuthor%5D&cauthor=true&cauthor_uid=25512732 https://www.ncbi.nlm.nih.gov/pubmed/?term=Kim%20YK%5BAuthor%5D&cauthor=true&cauthor_uid=19345809 https://www.ncbi.nlm.nih.gov/pubmed/?term=Weller%20RN%5BAuthor%5D&cauthor=true&cauthor_uid=19345809 https://www.ncbi.nlm.nih.gov/pubmed/?term=Pashley%20DH%5BAuthor%5D&cauthor=true&cauthor_uid=19345809 https://www.ncbi.nlm.nih.gov/pubmed/?term=Tay%20FR%5BAuthor%5D&cauthor=true&cauthor_uid=19345809 https://www.ncbi.nlm.nih.gov/pubmed/?term=Tay%20FR%5BAuthor%5D&cauthor=true&cauthor_uid=19345809