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Cementoenamel Junction (cementoenamel + junction)
Selected AbstractsEvaluation of fracture resistance in simulated immature teeth using resilon and ribbond as root reinforcements , An in vitro studyDENTAL TRAUMATOLOGY, Issue 4 2009Hiremath Hemalatha Material and Methods:, Sixty five freshly extracted human maxillary anterior teeth were prepared with a Peeso no. 6 to simulate immature teeth (Cvek's stage 3 root development). After instrumentation, each root was irrigated with sodium hypochlorite and with ethylene diamino tetra acetic acid to remove the smear layer. To simulate single visit apexification technique a 4,5 mm white Pro Root mineral trioxide aggregate plug was placed apically using schilder carrier. The teeth were divided into three experimental groups and one control group. Group I , control group (root canals instrumented but not filled); Group II , backfilled with thermoplastisized gutta-percha using AH plus sealer; Group III , reinforced with Resilon using epiphany sealer; Group IV , reinforced with Ribbond fibers using Panavia F luting cement. A Universal Testing Machine was used to apply a load, at the level of the lingual cementoenamel junction with a chisel-shaped tip The peak load to fracture was recorded and statistical analysis was completed using student's t -test. Results:, Values of peak load to fracture were 1320.8, 1604.88, 1620, and 1851newtons for Group I to Group IV respectively. The results of student's t -test, revealed no significant difference (P > 0.05,) between Group II and Group III. Comparison between Group IV and Group III and between Group IV and Group II revealed highly significant difference (P > 0.001). Conclusions:, Teeth reinforced with Ribbond fibers using Panavia F luting cement showed the highest resistance to fracture. Resilon could not strengthen the roots and showed no statistically significant difference when compared with thermopasticised gutta-percha in reinforcing immature tooth when tested with universal testing machine in an experimental model of immature tooth. [source] Bond strength of AH Plus and Epiphany sealers on root dentine irradiated with 980 nm diode laserINTERNATIONAL ENDODONTIC JOURNAL, Issue 9 2008E. Alfredo Abstract Aim, To evaluate the bond strength of AH Plus and Epiphany sealers to human root canal dentine irradiated with a 980 nm diode laser at different power and frequency parameters, using the push-out test. Methodology, Sixty canine roots were sectioned below the cementoenamel junction to provide 4-mm-thick dentine discs that had their root canals prepared with a tapered bur and irrigated with sodium hypochlorite, ethylenediaminetetraacetic acid and distilled water. The specimens were assigned to five groups (n = 12): one control (no laser) and four experimental groups that were submitted to 980 nm diode laser irradiation at different power (1.5 and 3.0 W) and frequency (continuous wave and 100 Hz) parameters. Half of specimens in each group had their canals filled with AH Plus sealer and half with Epiphany. The push-out test was performed and data (MPa) were analysed statistically by anova and Tukey's test (P < 0.05). The specimens were split longitudinally and examined under SEM to assess the failure modes after sealer displacement. Results, The specimens irradiated with the diode laser and filled with AH Plus had significantly higher bond strength values (8.69 ± 2.44) than those irradiated and filled with Epiphany (3.28 ± 1.58) and the nonirradiated controls (3.86 ± 0.60). The specimens filled with Epiphany did not differ significantly to each other or to the control (1.75 ± 0.69). There was a predominance of adhesive failures at Epiphany,dentine interface (77%) and mixed failures at AH Plus,dentine interface (67%). Conclusions, The 980 nm diode laser irradiation of root canal dentine increased the bond strength of AH Plus sealer, but did not affect the adhesion of Epiphany sealer. [source] Taurodontism: a review of the condition and endodontic treatment challengesINTERNATIONAL ENDODONTIC JOURNAL, Issue 5 2008H. Jafarzadeh Abstract Taurodontism can be defined as a change in tooth shape caused by the failure of Hertwig's epithelial sheath diaphragm to invaginate at the proper horizontal level. An enlarged pulp chamber, apical displacement of the pulpal floor, and no constriction at the level of the cementoenamel junction are the characteristic features. Although permanent molar teeth are most commonly affected, this change can also be seen in both the permanent and deciduous dentition, unilaterally or bilaterally, and in any combination of teeth or quadrants. Whilst it appears most frequently as an isolated anomaly, its association with several syndromes and abnormalities has also been reported. The literature on taurodontism in the context of endodontics up to March 2007 was reviewed using PubMed, MEDLINE and Cumulative Index to Nursing & Allied Health Literature. Despite the clinical challenges in endodontic therapy, taurodontism has received little attention from clinicians. In performing root canal treatment on such teeth, one should appreciate the complexity of the root canal system, canal obliteration and configuration, and the potential for additional root canal systems. Careful exploration of the grooves between all orifices particularly with magnification, use of ultrasonic irrigation; and a modified filling technique are of particular use. [source] Fracture strength of bovine incisors after intra-radicular treatment with MTA in an experimental immature tooth modelINTERNATIONAL ENDODONTIC JOURNAL, Issue 9 2007E. A. Bortoluzzi Abstract Aim, To evaluate, using an experimental immature tooth model, the fracture resistance of bovine incisors submitted to different reinforcement treatments with mineral trioxide aggregate (MTA). Methodology, An immature tooth model was created by sectioning the coronal and apical portions of 40 bovine incisors 8 mm above and 12 mm below the cementoenamel junction. The root canals were irrigated with 1.0% sodium hypochlorite. They were enlarged both coronally and apically using number 703 carbide burs (ISO: 500,104-168-007-021) and their internal diameter was standardized to 2.1 mm. The specimens were assigned to four groups (n = 10): GI-control (without filling); GII-apical MTA plug + filling with gutta-percha and endodontic sealer; GIII-filling with MTA; GIV-apical MTA plug + filling with MTA + metallic post (Reforpost I). A polyether impression material was used to simulate the periodontal ligament. The specimens were submitted to a compressive load at a crosshead speed of 0.5 mm min,1 in a servo-hydraulic universal testing machine (MTS 810) applied at 45° to the long axis of the tooth until failure. Data were submitted to statistical analysis by the Kruskal,Wallis test at 5% significance level. Results, GIV presented the highest fracture resistance (32.7N) and differed significantly from the other groups (P < 0.05). No statistically difference was found between GII (16.6N) and GIII (23.4N) (P > 0.05). GIII had a significantly higher fracture resistance than GI (P < 0.05). Conclusions, The use of MTA + metallic post as an intra-radicular reinforcement treatment increased the resistance to fracture of weakened bovine teeth in an experimental immature tooth model. [source] Three phosphor plate systems and film compared for imaging root canalsINTERNATIONAL ENDODONTIC JOURNAL, Issue 4 2001A. C. Shearer Abstract Aim The aim of this study was to compare three phosphor plate intraoral imaging systems (Digora (DA), Digident (DT), Denoptix (DX)) and E-speed conventional film (CF) for the imaging of root canals. Methodology Sixty extracted permanent teeth were exposed using CF, DA, DT and DX. The length of root canal visible from its most apical extent to a line drawn at the level of the cementoenamel junction was measured and this was expressed as a percentage of the distance between the radiographic apex and the cementoenamel line. All images were examined concurrently by two examiners. Films were viewed under standardized conditions and DA, DT and DX images were viewed directly from the monitor screen. The images on the monitor were enhanced to give the subjectively clearest image. Results The mean percentage of canal visible on CF was 90%, DA 78%, DT 81% and DX 83%. The difference was significant for CF,DA (P < 0.001) and CF,DT (P = 0.001). There was no statistically significant difference for CF,DX or between any of the three phosphor plate imaging systems. Conclusions It is concluded that a greater length of root canal was visible on conventional film than on three phosphor plate imaging systems and that this may be of clinical significance. [source] Fracture Resistance of Endodontically Treated Teeth Restored with Three Different Prefabricated Esthetic PostsJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 1 2003PAULO C. A. MACCARI DDS ABSTRACT Purpose: This study was undertaken to evaluate the role of composition of prefabricated esthetic posts in fracture resistance of endodontically treated teeth in vitro. Materials and Methods: Thirty human, single-rooted teeth (maxillary central incisors and canines) with similar root dimensions, extracted for therapeutic reasons, were used in this study. The crowns were removed below the cementoenamel junction to obtain a standard root length of 17 mm. The roots were endodontically treated following the conventional manual technique and randomly assigned to three groups (n = 10) according to the post used: Aestheti-Post, Bisco, Schaumberg, Illinois; FibreKor Post, Jeneric/Pentron, Wallingford, Connecticut; and CosmoPost, Ivoclar Vivadent, Schaan, Liechtenstein. The root canals were rendered patent, and the root preparations were standardized through flaring with the manufacturers' drills included in the respective kits. The posts were cemented with an adhesive system and a resin cement (All-Bond 2 and C & B, Bisco, respectively), according to the manufacturers' directions. Composite resin (Tetric Ceram, Ivoclar Vivadent) crowns were built up using a preformed polyester matrix, and the specimens were mounted in metallic rings with cold-cure acrylic resin and kept in saline solution at 4°C for 24 hours. Fracture resistance was then determined using an EMIC DL-2000 universal testing machine. The crosshead speed was 0.5 mm/min with the 45-degree compressing load at the middle third of the crown. Data were analyzed using one-way analysis of variance and Tukey'stest (p<.001). Results: Mean fracture resistance was as follows: Aestheti-Post, 83.5 kgf; FibreKor Post, 85.7 kgf; and CosmoPost, 36.5 kgf. The fracture strength of CosmoPost was significantly lower than that of the other posts. Teeth restored with CosmoPost had post fractures, and in three specimens, those were associated with root fractures. Teeth restored with the other two posts presented fractures on the composite crowns. CLINICAL SIGNIFICANCE Compared with ceramic posts, carbon-fiber and glass-fiber prefabricated esthetic posts provide endodontically treated teeth higher fracture resistance. [source] The effect of retainer thickness on posterior resin-banded prostheses: a finite element studyJOURNAL OF ORAL REHABILITATION, Issue 11 2004T.-S. Lin summary, According to its design concept, a resin-bonded prosthesis, compared with the conventional fixed partial denture, is a weak and unstable structure. Therefore, a resin-bonded prosthesis induces a higher failure rate, especially in the posterior region. Recently, adhesion agents have been profoundly improved. However, the design guidelines of posterior resin-bonded prostheses (RBP) have seldom been evaluated from a biomechanical perspective. The objective of this study was to investigate the biomechanical effects of the retainer thickness on posterior RBP using the finite element method. A solid model of a posterior mandibular resin-bonded prosthesis, which employed the second molar and second premolar as the abutment teeth, was constructed and meshed with various retainer thickness (ranging from 0·2 to 1·0 mm). Horizontal and vertical loadings of 200 N were applied respectively at the central fossa of the pontic to examine the stress level at the interface between the retainer and abutment teeth. All exterior nodes in the root, below the cementoenamel junction were fixed as the boundary condition. The results showed that horizontal loading would induce higher interfacial stresses than the vertical loading which indicated that the horizontal component of the occlusal force plays a more important role in evaluating the debonding phenomenon. Further, the peak interfacial stresses increased as the retainer thickness decreased and, based on the fitted relation between retainer thickness and interfacial stresses, a 0·4 mm retainer thickness was suggested as the minimum required to prevent severe interfacial stresses increasing. [source] Evaluation of penetration and adaptation of three different sealers: a SEM studyJOURNAL OF ORAL REHABILITATION, Issue 9 2003S. Sevimay Summary, In this study, dentinal penetration and adaptation of three endodontic sealers were evaluated by using scanning electron microscope (SEM). Seventeen recently extracted, human maxillary anterior teeth were used. After the crowns were removed from the cementoenamel junction, the root canals were instrumented. The teeth were then randomly divided into three groups of five roots each and two teeth were used as controls. The smear layer was removed with EDTA and NaOCl. The canals were obturated with AH 26, CRCS, RSA sealers and gutta-percha using lateral condensation technique. Each root was sectioned longitudinally and then prepared for SEM evaluation. The SEM results showed that AH 26 was the best sealer penetrating into dentinal tubules and adapted to dentinal walls when compared with the CRCS and RSA. The CRCS and RSA occluded the orificies of dentinal tubules. The RSA showed that the penetration was less than AH 26 and more than CRCS. [source] Fracture Resistance of Endodontically Treated Teeth: Three Walls versus Four Walls of Remaining Coronal Tooth StructureJOURNAL OF PROSTHODONTICS, Issue 1 2009Siriporn Arunpraditkul DDS Abstract Purpose: The purpose of this study was to evaluate the fracture resistance of endodontically treated teeth between those with four walls and those with three walls of remaining coronal tooth structure and the effect of the site of the missing coronal wall. Materials and Methods: Thirty-two endodontically treated second mandibular premolars were decoronated, leaving 3 mm above the cementoenamel junction (CEJ). A 0.5-mm-wide chamfer was prepared 1 mm above the CEJ. The teeth were randomly divided into four groups. Group 1 had four walls of coronal tooth structure, whereas groups 2, 3, and 4 had only three walls, missing the buccal, lingual, and mesial wall, respectively. The cast dowel and cores and crowns (Ni,Cr alloy) were cemented with zinc phosphate cement. A compressive load was applied 45° to the long axis, 2 mm below the buccal cusp, with an Instron machine until failure at a crosshead speed of 5 mm/min. Failure load (kg) and mode of failure were recorded. Data were analyzed with one-way ANOVA and Scheffé tests (p < 0.05). Results: Group 1 had the highest fracture resistance (1190.3 ± 110.5 kg), significantly different from the other groups (p < 0.05) (group 2: 578.5 ± 197.4 kg; group 3: 786.6 ± 132.8 kg; group 4: 785.4 ± 289.9 kg). There were no significant differences among the test groups. The mode of failure in group 1 was a horizontal root fracture, whereas that of the other groups was either vertical or oblique fracture. Conclusions: Teeth with four walls of remaining coronal dentine had significantly higher fracture resistance than teeth with only three walls. The site of the missing coronal wall did not affect the fracture resistance of endodontically treated teeth. [source] | ||||||||||