Effect of dowel space preparation and composite cement thickness on retention of a prefabricated dowel

PURPOSE: This investigation examined what effect cement thickness had on retention of prefabricated endodontic dowels luted with a composite resin cement (Panavia 21 OP; J Morita, Irvine, CA) into canals previously obturated with gutta percha and a eugenol-based sealer. MATERIALS AND METHODS: Sixty-four single-rooted teeth were decoronated, filed, cleaned, and sequentially shaped with sizes 2-5 Gates Glidden drills (Dentsply/Maillefer, Tulsa, OK) and 0.12 taper rotary instrumentation. Teeth were then divided into 4 groups of 16 specimens each. All specimens were obturated with gutta percha and a eugenol-based sealer. Dowel space preparation and dowel cementation were completed 1 week after obturation. Ten-millimeter-deep dowel spaces were prepared using dowel drills with 4 different diameters: size 5 Parapost drill (Group 1; Coltene/Whaledent, Mahwah, NJ); size 5.5 Parapost drill (Group 2; Coltene/Whaledent); size 6 Gates Glidden drill (Group 3; Dentsply/Maillefer); size 6 Parapost drill (Group 4; Coltene/Whaledent). Size 5 Paraposts were then cemented with Panavia 21 OP. After 48 hours of storage, specimens were mounted in polyvinyl chloride (PVC) pipe with acrylic, and the dowels were removed in tensile mode using a universal testing machine at 1 mm/min, with data recorded in kilograms. RESULTS: (all values in kilograms) Group 1 (Parapost 5) mean = 15.07, 95% confidence interval (CI) = +/-6.11; Group 2 (Parapost 5.5) mean = 25.60, 95% CI = +/-7.39; Group 3 (Gates-Glidden 6) mean = 43.15, 95% CI = +/-7.81; Group 4 (Parapost 6) mean = 37.75, 95% CI = +/-6.35. Analysis of variance and Bonferroni tests revealed that Group 3 had significantly greater mean retention strength values than Group 1 and Group 2 (p <.05), and that Group 4 had significantly greater mean retention strength values than Group 1 (p <.05). CONCLUSIONS: Paraposts cemented with Panavia 21 OP showed significantly greater retention in oversized dowel spaces compared with dowel spaces prepared with the manufacturers' matched dowel-drill set.     

Effect of eugenol-containing and resin endodontic sealers on retention of prefabricated metal posts cemented with zinc phosphate and resin cements

PurposeThe aim of this study was to compare the effects of two endodontic sealers on the retention of posts cemented with zinc phosphate or resin cement.Materials and methodsCrowns of 72 mandibular premolars were removed at the cementoenamel junction. Root canals were prepared and specimens were randomly divided into two groups of 36. In each group, 12 specimens were obturated with gutta percha only; 12 specimens with gutta percha/ZOE sealer and 12 specimens with gutta percha/AH26. In the first group, 10 mm Post spaces were prepared with Peeso reamers size 4 and, size 5 stainless steel Paraposts were cemented in with zinc phosphate. In the second group, 10 mm Post spaces were prepared with Fiber Lux size 5.5 drills and size 5 Paraposts were cemented with Panavia F_2.0. After mounting in resin blocks, posts were pulled out by universal testing machine at 1 mm/min and results were analyzed by two-way ANOVA and Dunnett test.ResultsMean forces (in Newtons) required to remove posts cemented with zinc phosphate in canals obturated without sealer, with ZOE, and with AH26 sealers were 270 ± 83, 281 ± 128 and 266 ± 67, respectively; and for posts cemented with Panavia F_2.0 were 520 ± 290, 464 ± 212 and 229 ± 108, respectively. Statistical analysis showed that AH26 significantly reduced retention of posts cemented with Panavia F_2.0 (p < 0.05).ConclusionDifferent sealers had no significant effect on retention of posts cemented with zinc phosphate. However posts cemented with Panavia F_2.0 showed reduced retention in canals obturated with AH26.     

Effect of ultrasonic vibration and various sealer and cement combinations on titanium post removal

The purpose of this study was to determine the effect of ultrasonic vibration on the force required to remove prefabricated posts. Ninety-six extracted human canines were divided into eight groups, which were prepared and obturated with gutta-percha and either a eugenol-containing (Roth's 801 Elite) or eugenol-free (AH26) sealer. Titanium #6 Parapost XH posts were cemented with either zinc phosphate or Panavia 21 resin cement. One half of the sample was subjected to ultrasonic vibration for 16 min at the post-dentin interface, whereas the other half received no vibration (controls). Each combination of sealer, cement, and vibration status was subjected to tensile load to failure using an Instron testing machine. Posts cemented in teeth obturated with gutta-percha and AH26 sealer demonstrated significantly greater resistance to dislodgement, compared with teeth obturated with gutta-percha and Roth's 801 Elite sealer. There was no statistical difference in retention of posts cemented with either zinc phosphate or Panavia 21, regardless of the sealer used. Additionally ultrasonic vibration increased post retention for both cements.     

Effect of endodontic sealers on dowels luted with resin cement

PURPOSE: This study evaluated the retention of prefabricated parallel-sided dowels luted with resin cement in extracted teeth that were obturated with gutta percha using a eugenol sealer or a calcium hydroxide sealer. MATERIALS AND METHODS: Extracted maxillary incisor roots (N = 51) were instrumented to simulate conventional root canal therapy and divided into 3 groups (n = 17). One group was not obturated. Second and third groups were obturated with gutta percha using a eugenol-containing or calcium hydroxide-containing sealer. Gutta percha was removed using a heated plugger, and dowel spaces were prepared to a 7 mm depth. Dowel space walls were acid etched and primed, and prefabricated stainless steel dowels were luted using resin cement. After 24 hours, the load required to dislodge each dowel along a path parallel to its long axis was measured and recorded. A one-way analysis of variance (alpha = 0.05) was performed to identify differences in the means among groups. The incidence of failure within the cement or at the dentin-cement interface was also recorded. RESULTS: No statistically significant difference was found among the control (159.9 +/- 96.3 N), eugenol sealer (153.1 +/- 77.3 N), and calcium hydroxide sealer (192.0 +/- 89.3 N) groups. Nearly all specimens displayed adhesive failure at the dentin-resin cement interface. CONCLUSIONS: Conventional endodontic obturation using a eugenol-containing or a calcium hydroxide-containing endodontic sealer did not affect retention of prefabricated stainless steel dowels luted with resin cement.     

Effect of three root canal sealers on the retentive strength of endodontic posts luted with a resin cement

AIM: This investigation examined what effect three different sealers had on retention of endodontic posts (Parapost) luted with a resin cement (Panavia 21 OP). METHODOLOGY: Sixty-four single-rooted teeth were decoronated, filed, cleaned, and shaped with a size 5 Gates-Glidden drill and 0.12 taper G.T. rotary instrumentation (Dentsply/Tulsa Dental). Teeth were then divided into four groups of 16 each. Group 1 was not obturated, and served as a control. The other three groups were obturated with gutta-percha using a different sealer for each group. Group 2 used a eugenol containing sealer (Kerr Pulp Canal Sealer), group 3 a resin sealer (AH-26), and group 4 a calcium hydroxide sealer (Sealapex). After 1 week's storage at 100% humidity, 10-mm deep post spaces were prepared with a size 6 Gates-Glidden drill, and size 5 Paraposts were cemented. Following 48 h of storage, samples were mounted in a PVC pipe with acrylic, and the posts were removed vertically using a universal testing machine at 1 mm min-, with data recorded in kilograms. RESULTS: The mean values of force required to remove the posts were: group 1 = 61.80, SD = 16.21; group 2 = 43.14, SD = 14.66; group 3 = 48.54, SD = 17.84; group 4 = 53.52, SD = 18.77. Using anova and Bonferroni tests, group 1 demonstrated significantly greater mean retention strength values than group 2, but no other significant differences existed between groups. CONCLUSION: The chemical formulation of root canal sealers did not significantly affect the retention of endodontic posts luted with resin cement.     

Effect of different root canal obturating materials on push-out bond strength of a fiber dowel

Purpose: During dowel space preparation, the instrumentation forms a thick smear layer along with sealer‐occluded dentinal tubules. The purpose of this study was to evaluate the effect of different obturating materials on push‐out bond strength of a fiber dowel. Materials and Methods: Fifty human uniradicular teeth were decoronated and prepared using the step‐back technique. The specimens were divided into five groups on the basis of obturating materials: group I received no obturation; group II (ZOE) gutta‐percha and zinc oxide eugenol sealer; group III (ZOAH) gutta‐percha and AH plus sealer; group IV (GF) GuttaFlow; and group V (RE) with Resilon Epiphany system. Dowel spaces were made with manufacturer's provided drills, and a fiber dowel was luted. Horizontal slices were obtained from the middle third, and push‐out bond strength (S) was evaluated. Statistical analysis was carried out using one‐way ANOVA and post hoc Tukey's test. Results: The push‐out bond strength values in the control group, ZOE, ZOAH, GF, and RE were 9.303 ± 0.565 MPa, 8.859 ± 0.539 MPa, 8.356 ± 0.618 MPa, 9.635 ± 0.435 MPa, and 8.572 ± 0.256 MPa, respectively. There was no statistically significant difference between the S values of all the groups (p > 0.05). Conclusion: There was no effect of different tested obturating materials on the push‐out bond strength of fiber dowels; however, further studies should be conducted.     

An evaluation of sealing ability of endodontic materials as root canal sealers

An in vitro dye leakage study was carried out to compare the apical microleakage of vitapex (calcium hydroxide based paste) when used with single gutta percha cone with that of dentalis KEZ (calcium hydroxide and zincoxide eugenol based sealer) and zincoxide-eugenol sealer when used with laterally condensed gutta percha obturation technique. One hundred single rooted human anterior teeth were instrumented and randomly divided into three experimental groups of 30 teeth each and two control groups of 5 teeth each. Teeth in the first group were obturated using a single master gutta percha cone and vitapex as root canal sealer and those of second group were obturated with laterally condensed gutta percha using dentalis KEZ as sealer. Third experimental group was filled with laterally condensed gutta-percha using zinc-oxide eugenol as sealer. Teeth were then suspended in 2% methylene blue. After this, teeth were demineralized dehydrated and cleared. Linear dye penetration was determined under stereomicroscope (x10) with calibrated eye piece. Results of this study showed that calcium hydroxide based endodontic material leaked comparatively less as compared to zinc oxide Eugenol sealer. Vitapex with single gutta-percha cone provided an adequate apical Seal against dye penetration.     

Retention of posts cemented with various dentinal bonding cements

This investigation evaluated the retention of preformed posts with four different cements: C & B Metabond, Panavia, All-Bond 2, and Ketac-Cem. Sixty intact maxillary canines were selected for the study. The clinical crowns were removed and endodontic therapy done on each root, which was then prepared to receive prefabricated posts. The 60 samples were divided into four groups of 15, and the posts in each group were cemented with one of the four cements. The roots were mounted in acrylic resin blocks and the posts were separated from the canals with an Instron testing machine. Analysis of the forces needed to dislodge the posts with analysis of variance and Student-Newman-Keuls test disclosed that C & B Metabond cement was the most retentive (p < 0.05). No difference in retention was recorded between Ketac-Cem and Panavia cements. All-Bond 2 cement was the least retentive of cements.     

糊剂输送方式对根尖封闭性影响的研究

目的比较根充糊剂输送方式对根尖封闭性的影响。方法选择100颗离体单根管前牙，使用手用Protaper镍钛器械逐步后退法预备根管，并制备桩腔。样本随机分为5组。A组为主尖输送糊剂，B组为K锉输送糊剂，C组为侧压针输送糊剂，D组为阳性对照组，E组为阴性对照组。其中3个实验组再各分为2个亚组：a亚组（副尖不带糊剂）与b亚组（副尖带糊剂）。使用葡萄糖氧化酶比色测定法测定微渗漏实验第1、2、4、7、10、15、20、25、30天时的根尖微渗漏情况，对不同糊剂输送方式下的根尖封闭性能进行比较。结果不同实验组间的微渗漏差异有统计学意义（F=4.832，P=0.001），各亚组间的微渗漏差异无统计学意义（P>0.05），其中Aa组及Ab组的微渗漏最小。结论不同糊剂输送方式对根尖封闭性有影响，主尖输送糊剂可以获得最好的即刻根尖封闭效果；副尖带与不带糊剂根管治疗后的根尖封闭性能无显著差异。为了获得较好的根尖封闭效果并简化临床操作，推荐使用主尖带糊剂、副尖不带糊剂的糊剂输送方式。     

An in vitro comparative evaluation of fracture resistance of endodontically treated teeth obturated with different materials

The aim of this study was to evaluate the in vitro effect of various obturating materials on fracture resistance of root canal treated teeth. Sixty freshly extracted human mandibular premolars were used. After standardizing the length to 13 mm, the teeth were biomechanically prepared and divided into four groups based on type of obturating materials used. Teeth were embedded in acrylic resin and fracture strength was measured using a universal testing machine. Data obtained was evaluated statistically using one-way ANOVA and the unpaired t-test. Teeth obturated with AH Plus and gutta percha showed higher fracture resistance than those obturated with Resilon-Epiphany. The results suggested that the group obturated with gutta percha and zinc oxide-eugenol sealer had the lowest fracture resistance. No statistically significant difference was found between the unobturated (control) group and the zinc oxide-eugenol group.     

Effectiveness of hand and rotary instrumentation for removing a new synthetic polymer-based root canal obturation material (Epiphany) during retreatment

Aim To evaluate the effectiveness of hand and rotary instrumentation for removal of vertically compacted Epiphany and gutta‐percha during retreatment. Methodology Sixty extracted single‐rooted maxillary central incisors were enlarged to size 40 using FlexMaster instruments. The teeth were randomly divided into four groups of 15 specimens each. The canals of two groups were obturated using vertically compacted Epiphany. The others were filled with vertically compacted gutta‐percha and AH Plus sealer. One Epiphany group and one gutta‐percha group was reinstrumented with Gates Glidden burs and Hedström files. In the other two groups, obturation material was removed using Gates Glidden burs and RaCe rotary instruments. After clearing the roots, the area of remaining obturation material on the root canal wall was measured using a computer image analysis program. Statistical analysis was performed using Repeated Measures Analysis of Variance and anova . Results Retreatment of specimens obturated with gutta‐percha showed significantly more remaining obturation material than specimens filled with Epiphany (P < 0.05). No difference was found between the removal with Hedström files and with RaCe instruments (P > 0.05). Regarding the mean time of retreatment and time required for reaching the working length, Hedström files were significantly faster than RaCe instruments (P < 0.05). The times did not depend on the kind of obturation material (P > 0.05). Conclusions Vertically compacted Epiphany in combination with Epiphany Root Canal Sealant was removed more effectively than gutta‐percha and AH Plus sealer. Hedström files were more rapid than RaCe rotary instruments.     

Comparison of Two Luting Agents Used for the Retention of Cast Dowel and Cores

PURPOSE: The first purpose of this study was to compare the retentive values of zinc phosphate and Panavia F resin cements when used for luting cast dowel and cores. The second purpose was to determine whether the use of a lubricant when making the resin pattern for a custom dowel and core would have an effect on the final retention of dowels cemented with either zinc phosphate or Panavia F cements. METHODS AND MATERIALS: Sixty-three caries-free extracted single-rooted human teeth were randomly divided into three groups of 21. Root canal preparations were standardized for all 63 teeth. Clinical protocols for fabricating and cementing dowel and core restorations were examined, comparing zinc phosphate and Panavia F resin cements. Direct dowel patterns were fabricated using the Para Post system and cast in a noble metal alloy. Group I dowel spaces were lubricated with GC lubricant prior to dowel pattern fabrication and cleaned with Cavidry solvent before cementing the cast dowel and core with zinc phosphate cement. Group II dowel spaces were rinsed with water only prior to dowel pattern fabrication. The dowels and cores in this group were cemented with Panavia F resin cement. Group III dowel spaces were lubricated with GC lubricant prior to dowel pattern fabrication; the dowel spaces were cleaned with Cavidry solvent before the cast dowel and cores were cemented with Panavia F cement. The tensile force necessary to remove the cast dowel and cores was determined using a universal testing machine. Results were statistically analyzed using one-way ANOVA and Tukey's HSD test. RESULTS: The dowels and cores in Group I had significantly higher retentive values than either of the two Panavia F groups (p< or = 0.001). No difference in retentive values (p > 0.05) was found between dowels luted with either of the lubricating agents in the Panavia F groups. CONCLUSIONS: Zinc phosphate cement had higher retentive values when cementing cast dowel and cores than Panavia F. The type of lubricant used for the resin dowel fabrication (water or GC lubricant that was removed with a solvent) had no effect on the retention of cast dowels cemented with Panavia F.     

Post retention: the effect of sequence of post-space preparation, cementation time, and different sealers.

Many endodontic sealers contain constituents that have been shown to inhibit the polymerization of resin cements. This may be important when prefabricated posts are cemented at the same appointment as root canal obturation. This study evaluated the effects of cementing posts with a resin cement immediately or at a delayed time period after obturation using Roth's 801 Elite Grade or AH26 sealer cements. The contribution of mechanical post-space preparation was also assessed as a critical variable. One hundred twenty extracted canines were randomly divided into eight experimental groups. The variables evaluated were the order of post preparation (either before or after obturation), the type of sealer used, and the time of post cementation. All teeth received a stainless steel #6 Parapost XP cemented with a resin cement, Panavia 21. Each experimental group underwent tensile testing for retention using an Instron universal testing machine. For both sealers posts cemented in teeth in which the canal was obturated before post-space preparation and thus had sealer-contaminated dentin removed by the space preparation procedure had significantly higher retentive values than those obturated after post-space preparation in which contaminated dentin might remain. Sealer used and time of cementation had no specific effect on retention. Achieving a clean, "freshened" dentinal surface during mechanical post-space preparation seems to be a critical variable for post retention when a resin cement is used.     

Leakage along warm gutta-percha fillings in the apical canals of curved roots

Abstract – The aim of this study was to investigate the leakage along the apical portion of warm gutta‐percha obturated curved canals. Human mandibular premolars with single, curved (21°–40°) canals were prepared using the Lightspeed technique. Two groups of prepared canals, matched according to curvature and prevalence of apical transportation, were obturated by two techniques. Coronal gutta‐percha was removed immediately after root obturation was completed to simulate the procedure for post space preparation. Leakage along the apical 3 mm of root filling was measured with a fluid transport device. Vertical condensation of warm gutta‐percha and Pulp Canal Sealer provided less leakage than Thermafil plastic obturators and AH26 sealer (P=0.002).     

An in vitro evaluation of the contents of root canals obturated with gutta percha and AH-26 sealer or Resilon and Epiphany sealer

The purpose of this study was to compare the contents of root canals obturated with gutta percha and AH-26 sealer (Dentsply, Tulsa, OK) to canals obturated with the Resilon and Epiphany (Pentron, Wallingford, CT) system. Canal contents were assessed by determining the percentage of canal space occupied by core material, sealer, voids, and debris. Forty extracted human maxillary anterior teeth were instrumented, and the teeth were randomly assigned to either the gutta percha/AH 26 group or the Epiphany/Resilon group. Canals were obturated, and the teeth were subsequently embedded in resin and sectioned horizontally at 2, 4, and 6 mm from the anatomic apex. Sections were photographed by using a low vacuum scanning electron microscope. Image-J (Wayne Rasband; National Institute of Health, Bethesda, MD) software was used to quantify the proportion of core material, sealer, voids, and debris in each canal. Percentages and statistical comparisons for each method were compared. There were no significant differences found among the two groups in terms of the percentage of core (p = 0.9), sealer (p = 0.58), debris (p = 0.999), or voids (p = 1.00). Additionally, there were no differences in the percentage of core material, sealer, debris, or voids at any of the examined levels (2, 4, or 6 mm).     

Effect of Obturating Systems,Dowel Materials,and Adhesive Luting Techniques on the Resistance to Fracture of Endodontically Treated Teeth

Purpose: The aim of this study was to assess the role of obturating systems, dowel materials, and adhesive techniques on the resistance to fracture of endodontically treated teeth. Material and Methods: Eighty maxillary central incisors were selected and randomly divided into two groups according to the obturating system (n = 40); group I: gutta‐percha and Roeko sealer; group II: RealSeal. Both groups were further subdivided into two subgroups; subgroup A: using ceramic dowels (Cosmopost); subgroup B using fiber dowels (Easy Post). Each subgroup was assigned to two divisions according to the adhesive luting technique; division V (total‐etch) Variolink II resin cement; division U (self‐adhesive) RelyX Unicem. Composite core build‐up was made using a core former. Each specimen was loaded 2 mm from its incisal edge on the palatal side at a 135° angle with the long axis of the tooth using a universal testing machine with a load cell of 5 KN at a crosshead speed of 0.5 mm/min until fracture. Failure loads were recorded in N. Scanning electron microscopic examination at the dentin/resin interface (1000x) was performed. Three‐way ANOVA was used to test the effect of obturating system, dowel material, adhesive technique, and their interactions (obturating system * dowel material, obturating system * adhesive, dowel material * adhesive, obturating system * dowel material * adhesive). Duncan's test was used for pairwise comparison. The significance level was set at p≤ 0.05. Statistical analysis was performed with SPSS 16.0. Results : The mean resistance to fracture (617.4 N) was statistically significantly higher in the ceramic dowel with gutta‐percha and Variolink (GP/C/V) group than in the other groups. The RealSeal and RelyX fiber dowel group's mean resistance was the lowest and was significantly lower than the other groups. Conclusions : In this study, three factors played a part in enhancing the resistance to fracture of endodontically treated teeth. High resistance to fracture was achieved when ceramic dowels were luted with total‐etch technique in gutta‐percha‐obturated teeth.     

Root canal adhesive filling in dogs' teeth with or without coronal restoration: a histopathological evaluation

The purpose of this study was to evaluate in vivo the response of the periradicular tissues after endodontic treatment and root filling with Epiphany/Resilon (Penntron Clinical Technologies, LLC, Wallingford, CT) or gutta percha and new Sealapex (SybronEndo, Glendora, CA) in dogs' teeth with or without coronal restoration. Teeth without coronal restorations were used to assess the influence of continuous exposure to the oral environment on the periradicular tissues. Sixty root canals with vital pulps in three dogs were instrumented and obturated in a single session and randomly assigned to one of four groups as follows. group 1: root canal filling with Epiphany/Resilon with coronal restoration, group 2: root canal filling with Sealapex sealer and gutta percha with restoration, group 3: root canal filling with Epiphany/Resilon without restoration, and group 4: root canal filling with Sealapex sealer and gutta percha without coronal restoration. After 90 days, the animals were euthanized, and the maxillas and mandibles were removed and submitted for histologic processing. Longitudinal sections were obtained and stained with hematoxylin and eosin, Mallory's trichrome, and Brown and Brenn stains and examined under light microscopy. There were significant differences found between the four groups (p < 0.05). The results showed that roots canals filled with Epiphany/Resilon, with coronal restoration, had significantly less periradicular inflammation than roots canals filled with gutta percha and Sealapex, with coronal restoration (p = 0.021). No significant difference was observed in the intensity of inflammation between roots canals filled with Epiphany/Resilon with no restoration and roots filled with gutta percha and Sealapex with restoration (p = 0.269). Roots canals filled with gutta percha and Sealapex sealer without coronal restoration showed the greatest degree of periradicular inflammation.     

Effect of new obturating materials on vertical root fracture resistance of endodontically treated teeth

The aim of this study was to compare vertical forces at fracture of teeth obturated with different materials. Single-rooted teeth were divided into five groups. The first group served as a negative control. The remaining four groups were shaped using ProTaper rotary files (Dentsply Maillefer, Ballaigues, Switzerland). The second group was obturated with gutta percha and a zinc oxide sealer. The third group was obturated with EndoRez points and EndoRez sealer (both from Ultradent, South Jordan, UT). The fourth group was obturated with Resilon (Pentron Clinical Technologies, Wallingford, CT) and RealSeal sealer (Pentron Clinical Technologies). The fifth group was obturated with Guttaflow (Colténe/Whaledent, Altst?tten, Switzerland). Roots were then fixed into a universal testing machine and loaded with a spreader until fracture. It was found that forces at fracture were statistically significantly higher in the Resilon and EndoRez groups. It was concluded that obturation of roots with resin-based obturation materials (Resilon and EndoRez) increased the resistance of root canal filled teeth to vertical root fracture.     

The effect of two root canal sealers on the retentive strength of glass fibre endodontic posts

This study was undertaken to examine the effect of eugenol-containing and non-eugenol-containing root canal sealers on the retention strength of glass fibre endodontic posts (ParaPost Fibre White) luted with a resin cement (ParaPost cement). We also examined the mode of failure that occurred visually by using scanning electron microscopy. Seventy-two single rooted, recently extracted, premolar teeth were root canal treated and randomly divided into two groups. Group 1 was obturated with gutta percha and a calcium hydroxide-based sealer (Sealapex, Kerr). Group 2 was obturated with gutta percha and a eugenol-based sealer (Tubli-Seal Kerr). The teeth were stored for 1 week in distilled water at 37 degrees C and then prepared for 9 mm posts with a 1.40-mm drill. The matching glass fibre post was luted with a resin cement following the manufacturer's instructions. The samples were stored for 1 week and thermocycled. The posts were removed from the root canals using a calibrated testing machine in tensile mode. The mean dislodging force for group 1 was 190.46 N and for group 2 was 183.8 N, with standard deviations of 54.9 and 56.0 N respectively. The t-test indicated no significant difference between the two groups. Failure of the posts occurred mainly within the resin layer. This study showed that under experimental conditions there was no statistically significant difference between Sealapex sealer and Tubli-Seal sealer on the retention of glass fibre posts using a resin cement.     

An in vitro investigation of Thermafil obturation at different temperatures

Abstract – The apical leakage of lower premolars obturated with Thermafil at three different temperatures was investigated in vitro. The temperatures were determined after calibration of the Thermaprep oven. The root canals of 35 extracted teeth were prepared chemomechanically and divided into three groups of 10 each with a control group of five. The root canals of the experimental group were obturated using plastic Thermafil obturators at three different temperatures 144, 120 and 100 C with the controls being obturated using laterally condensed gutta percha. The teeth were suspended in indian ink for 28 days prior to being cleared and the degree of apical leakage assessed. The results showed no significant difference (p > 0.05) in the apical leakage of the teeth obturated with Thermafil compared to laterally condensed gutta percha. There was a trend towards less leakage in the teeth obturated with Thermafil at the lower temperatures, this, however, was not significant (p > 0.05).