Evaluation of fracture resistance in root canal-treated teeth restored using different techniques.

OBJECTIVE: This study aimed to evaluate the effects of different coronal restoration techniques on fracture resistance of root canal-treated mandibular premolars with mesio-occluso-distal (MOD) cavities. MATERIALS AND METHODS: A total of 105 mandibular premolars were selected and randomly distributed into seven groups (n = 15). MOD cavities were prepared except the control group. Root canal treatments were performed. Each tooth was embedded in acrylic resin. Groups were classified as follows; G1: intact teeth (control), G2: unfilled MOD cavity, G3: MOD + composite resin, G4: 10-mm-long fiber post + composite resin, G5: 5-mm-long fiber post + composite resin, G6: Ribbond in the occlusal surface + composite resin, and G7: horizontal fiber post + composite resin. Specimens were loaded using a universal testing machine until fracture occurs. Fracture loads were recorded and statistical interpretations were made (α = 0.05). RESULTS: In Groups 1, 6, and 7, the greatest fracture resistance was shown and there were no significant differences among these groups (P > 0.05). No significant differences were detected among the Groups 3, 4, and 5 (P > 0.05), whereas the fracture resistances of Groups 1, 6, and 7 were significantly greater than these three groups (P < 0.05). Group 2 had the lowest fracture resistance of all groups (P < 0.05). CONCLUSION: Usage of horizontal post or occlusal Ribbond usage increased the fracture resistance of root canal-treated premolars with MOD cavities.

The effects of different irrigation protocols on removing calcium hydroxide from the root canals.

OBJECTIVE: The aim of this study was to evaluate the efficiencies of different irrigation protocols and solutions in the removal of calcium hydroxide (Ca[OH]2). MATERIALS AND METHODS: Sixty-eight maxillary incisors were used. Root canals were prepared and filled with Ca(OH)2. Two control (n = 4) and six experimental groups (n = 10) were adjusted: Group 1:1% peracetic acid (PAA) + master apical file (MAF); Group 2: 17% ethylenediaminetetraacetic acid (EDTA) + MAF; Group 3: 9% 1-hydroxyethylidene-1,1-bisphosphonate (HEBP) + MAF; Group 4: 1% PAA + ultrasonic activation (UA); Group 5: 17% EDTA + UA; Group 6: 9% HEBP + UA. The cleanliness of root canal thirds were evaluated with scanning electron microscopy. Statistical analysis were performed (α = 0.05). RESULTS: At coronal thirds; PAA + UA was superior to EDTA + MAF, HEBP + MAF; and PAA + MAF was superior to EDTA + MAF, HEBP + MAF (P < 0.05). At middle thirds; PAA + MAF and PAA + UA were superior to EDTA + MAF and EDTA + UA; and, PAA + UA was superior to HEBP + MAF (P < 0.05). There were no significant differences among the rest of the experimental groups (P > 0.05). CONCLUSION: Complete removal of Ca(OH)2could not be achieved by none of the irrigants at all root thirds.

Radiographic assessment of the technical quality and periapical health of root-filled teeth performed by general practitioners in a Turkish subpopulation.

AIM: The aim of this study was to evaluate by means of radiographs the technical quality of root fillings performed by dental practitioners. METHODS AND MATERIAL: Standardized periapical radiographs were made on 484 patients who received endodontic treatment in private practice. A total of 831 endodontically treated teeth with 1448 roots were evaluated for technical quality of the root canal filling and the periapical status of the teeth. Also, the apical status of each root-filled tooth was assessed according to the length, density, and taper of root fillings, and the presence of apical transportation, broken root instruments, and overfilled sealer or gutta-percha material was recorded for each root canal. RESULTS: Of the endodontically treated teeth 26.6% had healthy periapical tissues, while technically good endodontic treatment constituted 12.8%. Based on the treatment success, there was no significant difference between the tooth groups. Statistical analysis of the data did not demonstrate statistically significant differences between the various parameters that were evaluated (P < 0.05). CONCLUSIONS: Technical quality of root fillings in a population who received treatment in private practice was poor and was consistent with a low prevalence of apical health. The probable reasons for this failure are multifactorial and may be improved if the operators improve their skills with continuing postgraduate education programs.

Push-out bond strength of two new calcium silicate-based endodontic sealers to root canal dentine.

AIM: To assess the push-out bond strength of two new calcium silicate-based endodontic sealers in the root canals of extracted teeth. METHODOLOGY: Thirty extracted single-rooted central incisors of similar sizes were selected randomly and distributed to three groups (n = 10). All canals were instrumented using ProTaper rotary instruments to achieve tapered canal walls. Irrigation was performed using 5 mL 2.5% NaOCl between each instrument, and the smear layer was removed using 5 mL 17% EDTA. The canals were filled with three different sealers using a cold lateral compaction technique: group 1: AH Plus + gutta-percha, group 2: I Root SP + gutta-percha and group 3: MTA Fillapex + gutta-percha. Three horizontal sections were prepared at a thickness of 1 mm ± 0.1 in the apical, middle and coronal parts of each root. The test specimens were subjected to the push-out test method using a Universal Test Machine (Instron, Canton, MA, USA) that carried 1-mm, 0.5-mm and 0.3-mm plungers for coronal, middle and apical specimens, respectively. The loading speed was 1 mm min(-1) . The push-out data were analysed by two-way analysis of variance (anova) and the post hoc Holm-Sidak test, with significance set at P < 0.05. RESULTS: In the coronal specimens, there was no significant difference between the sealers. In the middle and apical segments, there was no significant difference between I Root SP and AH Plus groups. However, the I Root SP and AH Plus had significantly higher bond strength values than the MTA Fillapex (P < 0.05). In terms of root segments, the bond strengths in the middle specimens and the apical specimens were higher compared with the bond strengths in the coronal specimens (P < 0.05). There were no significant differences between the bond strengths in the middle and apical specimens. CONCLUSION: MTA Fillapex had the lowest push-out bond values to root dentine compared with other sealers.

Resistance to fracture of roots filled with three different techniques.

AIM: To compare the fracture resistance of roots filled with different materials. METHODOLOGY: Thirty-four freshly extracted human maxillary central incisor teeth with similar dimension were selected. Crowns were sectioned at the cemento-enamel junction, and the length of the roots were adjusted to 13 mm. Following the preparation of the root canals and final irrigation with EDTA and saline, the 10 root canals in group 1 were filled with Resilon cones and Epiphany sealer, the 10 root canals in group 2 were filled with gutta-percha and AH 26 and the 10 root canals in group 3 were filled with gutta-percha and MCS Canal Sealer. All materials were used with a cold lateral condensation technique. Four root canals remained unfilled and were used as a control group. Tests for fracture strength were performed using a universal testing machine and a round tip that had a diameter of 4 mm. The force was applied vertically with a constant speed of 1 mm min(-1). For each root, the force at the time of fracture was recorded in Newtons. Results were evaluated statistically with ANOVA and Tukey Honestly Significant Difference (HSD) tests. RESULTS: The mean force of fracture values was 1043 N, 967 N, 859 N and 517.5 N for groups 3, 1 and 2 and the control group, respectively. There was a significant difference (P < 0.01) between the experimental groups and the control group. No significant differences were found between the three experimental groups. CONCLUSIONS: All the materials used in the present study reinforced the prepared root canals.

Radiographic technical quality of root fillings performed by dental students in Turkey.

AIM: To evaluate the radiographic technical quality of root fillings performed by undergraduate students at a dentistry faculty in Turkey. METHODOLOGY: A random sample of 2000 records of patients who received dental treatment at the Faculty of Dentistry, University of Gazi between 2000 and 2003 was investigated. The final sample consisted of 1,893 root-filled teeth with 3,692 root canals in 1,654 dental patients. For each root-filled tooth, at least three periapical radiographs were examined: preoperative, working length determination and postoperative. The length, density and taper of root fillings were recorded. The length of root fillings was recorded as adequate, short or overfilled. Density of root fillings was recorded as adequate or inadequate. Taper of root fillings was recorded as adequate or inadequate. Results were evaluated statistically using one-way analysis of variance (anova) and chi-square analysis. RESULTS: Sixty-nine per cent, 53.2% and 68.3% of root fillings had adequate length, density and taper, respectively; only 33% of teeth fulfilled these three criteria at the same time. The relationship between the length, density and taper of the root filling and the presence of canal curvature was statistically significant (P < 0.001). There was no significant difference between maxillary and mandibular teeth according to the adequacy of the root fillings. The highest percentage of adequate root fillings was found in maxillary canines (51.5%). CONCLUSIONS: The percentage of adequate root fillings performed by undergraduate students was only 33%.

Effect of bonded restorations on the fracture resistance of root filled teeth.

AIM: To evaluate the fracture resistance of root filled maxillary premolars restored with different techniques. METHODOLOGY: One hundred and twenty single-rooted maxillary premolar teeth were divided randomly into six groups of 20 teeth and subjected to the following procedures: group 1: intact teeth. Group 2: endodontic access cavities prepared. Group 3: MOD cavities were prepared, root canals were filled and no restoration was placed. Group 4: teeth were prepared as group 3 and restored conventionally with amalgam. Group 5: teeth were prepared as group 3 and restored with amalgam using a bonding material. Group 6: teeth were prepared as group 3 and restored with composite resin using the same bonding material. Teeth were embedded in acrylic resin and the loads for fracture strength were applied vertically with a constant speed of 1 mm min(-1). Data were evaluated statistically with anova and Tukey's tests. RESULTS: The mean force of fracture values were 1191.41, 599.86, 233.03, 494.72, 962.81 and 856.48 N for groups 1, 2, 3, 4, 5 and 6, respectively. The fracture resistance of group 5 was similar to group 1 (P > 0.05). The mean force at fracture of group 5 and group 6 was not significantly different. The fracture resistance of groups 5 and 6 was significantly higher than group 4 (P < 0.001). CONCLUSIONS: The group, restored with conventional amalgam, had the weakest resistance to fracture when compared with the bonded restorations. No statistically significant differences were found between the bonded amalgam and composite resin groups.