Mahir Günday

Dentinal wall adaptation of thermoplasticized gutta-percha in the absence or presence of smear layer: a scanning electron microscopic study.

The dentinal adaptation of injected thermoplasticized gutta-percha and thermoplasticized gutta-percha resulting from Ultrafil and Thermafil systems was evaluated by scanning electron microscopy and compared with adaptation obtained with the lateral condensation of gutta-percha. Each method was evaluated with and without the smear layer removed. Scanning electron microscopic observations showed the thermoplasticized gutta-percha resulting from either system to have better dentinal wall adaptation than lateral condensation of gutta-percha in either the absence or presence of the smear layer. In the absence of smear layer, the adaptation of gutta-percha was improved in all groups. Although sealer was used, removing the smear layer was found to enhance the ability of the thermoplasticized gutta-percha to enter the patent tubules.

Evaluation of Sealing Properties of Thermafil and Ultrafil Techniques in the Absence or Presence of Smear Layer

The apical sealing abilities of two thermoplasticized gutta-percha techniques were evaluated. A total of 128 single-rooted teeth were divided into six groups in which Ultrafil, Thermafil, and lateral condensation techniques, with and without the smear layer, were used to obturate 20 roots in each group. The roots were implanted subcutaneously in rats for 90 days to expose the materials to vital tissue and tissue fluids. The roots were recovered, immersed in 1% methylene blue for 2 wk, cleared, and the dye penetration was measured using a dissecting microscope. Thermafil showed the least leakage with smear layer present and Ultrafil the least with it absent. The two thermoplasticized gutta-percha techniques both showed significantly less leakage than lateral condensation with and without the smear layer. Removing the smear layer reduced the leakage significantly in all groups.

Effect of calcium hydroxide and combinations of ledermix and calcium hydroxide on inflamed pulp in dog teeth

The effects of Ledermix+calcium hydroxide (Ca(OH)2) or Ca(OH)2 alone on inflamed pulp tissues of dogs were studied. Fifty-nine upper incisor teeth of 10 dogs were used. Class V cavities were prepared and filled with amalgam after placement of decayed dentin particles. After 7 days, the decayed dentin and alloy were removed, and the pulps of the teeth were exposed. Ledermix and Ca(OH)2 mixtures or Ca(OH)2 alone were applied to the cavities. At the end of 7, 30, and 90 days, the teeth were extracted and examined histopathologically. Inflammation was found to be more prevalent in the 7- and 30-day groups that were treated with the Ledermix+Ca(OH)2 combination, whereas fibrosis and necrosis were nearly similar in both groups. In the 90-day groups, no inflammation was seen. No difference between the two 90-day groups with regard to reparative dentin was found.

Effect of various mixing and placement techniques on the flexural strength and porosity of mineral trioxide aggregate.

INTRODUCTION The aim of this study was to evaluate the effect of mechanical and manual mixing as well as the effect of ultrasonic agitation during placement on the flexural strength and porosity of mineral trioxide aggregate (MTA). METHODS White ProRoot MTA and white MTA Angelus were used. One gram of each powder was mixed with a 0.34-g aliquot of distilled water. Specimens were mixed either by mechanical mixing of capsules for 30 seconds at 4500 rpm or by a saturation technique and application of a condensation pressure of 3.22 MPa for 1 minute. The mixed slurries of all materials were loaded into 2 × 2 × 25 mm molds for testing flexural strength and 3 × 4 mm molds for evaluation of porosity. Half of the specimens were placed in the stainless steel molds by using indirect ultrasonic activation. All specimens were incubated for 4 days. Micro-computed tomography was used to determine the porosity of each specimen, and a 3-point bending test was used to evaluate flexural strength. Tukey honestly significant difference and independent t tests were carried out to compare the means at a significance level of P < .05. RESULTS Irrespective of mixing and placement techniques applied, the flexural strength values of ProRoot MTA were significantly greater than those of MTA Angelus (P < .05). A medium negative correlation was found between flexural strength values and total porosity percentage. CONCLUSIONS Although mechanical mixing of encapsulated cements was quicker and provided more consistent mixes, this technique along with ultrasonic agitation was not associated with a significant advantage in terms of flexural strength and total porosity over manual mixing.

Evaluation of smear layer removal after use of a canal brush: an SEM study

OBJECTIVE The objective of this study was to evaluate smear layer removal after using the new CanalBrush (Coltene/Whaledent GmbH+Co. KG, Germany). STUDY DESIGN Twenty extracted maxillary anterior teeth were randomly divided into 2 equal groups. The canals of the teeth in each group were instrumented with ProTaper Universal rotary files (Dentsply Maillefer, Switzerland). Following each file use, the root canals in both groups were irrigated with 5.25% NaOCl and 15% EDTA. At the end of instrumentation, the canals in group 2 were flushed with 15% EDTA, then a CanalBrush was used for 30 seconds, and a final irrigation was conducted with 5.25% NaOCl. All teeth were processed for scanning electron microscopy (SEM), and the removal of the smear layer was examined in the apical, middle, and coronal thirds. Analyses of SEM images were performed by 2 independent evaluators in a blinded manner and using a 4-point scoring system. RESULTS The middle and apical thirds of the root canals in group 2 showed lower average scores than those in group 1, but the difference was not statistically significant. There was no significant difference in the coronal score between the groups (P > .05). CONCLUSIONS Irrigating with brushing tended to produce cleaner canal walls, but irrigating brushing was not significantly better than irrigation alone in removing the smear layer on the canal walls.

Effect of Varying Water-to-Powder Ratios and Ultrasonic Placement on the Compressive Strength of Mineral Trioxide Aggregate

INTRODUCTION The purpose of this study was to compare the compressive strength of mineral trioxide aggregate (MTA) when mixed with 2 different water-to-powder (WP) proportions using either hand or ultrasonic placement. METHODS Tooth-colored ProRoot MTA (Dentsply Maillefer, Ballaigues, Switzerland) and white MTA Angelus (Angelus Soluçoes Odontologicas, Londrina, Brazil) were investigated. One gram of each MTA powder was mixed with either 0.34 or 0.40 g distilled water. The 4 groups were further divided into 2 groups of 5 specimens for each of the following techniques: conventional (ie, hand placement) and placement using indirect ultrasonic activation for 30 seconds. All specimens were subjected to compressive strength testing after 4 days. The results were statistically analyzed with multivariate analysis of variance and Tukey Honestly Significant Difference tests at a significance level of P < .05. RESULTS The mean compressive strength values of ProRoot MTA (84.17 ± 22.68) were significantly greater than those of MTA Angelus (47.71 ± 14.29) (P < .01). Specimens mixed with the 0.34 WP ratio had higher compressive strength values (72.85 ± 25.77) than those mixed with the 0.40 WP ratio (56.69 ± 24.85) (P < .05). The highest compressive strength values were recorded for ProRoot MTA specimens that were mixed in the 0.34 WP ratio, and then the samples were placed with ultrasonic activation (mean = 91.35 MPa). The lowest values were recorded for MTA Angelus samples that were mixed in the 0.40 WP ratio, and the specimens were placed without ultrasonic activation (mean = 36.36 MPa). Ultrasonic activation had no significant difference in terms of compressive strength. CONCLUSIONS When using ProRoot MTA and MTA Angelus, higher WP ratios resulted in lower compressive strength values. Ultrasonication had no significant effect on the compressive strength of the material regardless of the WP ratio that was used. Therefore, adherence to the manufacturers recommended WP ratio when preparing MTA for use in dental applications is advised.

Direct composite laminate veneers: three case reports.

Re-establishing a patient’s lost dental esthetic appearance is one of the most important topics for contemporary dentistry. New treatment materials and methods have been coming on the scene, day by day, in order to achieve such an aim. Most dentists prefer more conservative and aesthetic approaches, such as direct and indirect laminate veneer restorations, instead of full-ceramic crowns for anteriors where aesthetics is really important. Laminate veneers are restorations which are envisioned to correct existing abnormalities, esthetic deficiencies and discolo-rations. Laminate veneer restorations may be processed in two different ways: direct or indirect. Direct laminate veneers have no need to be prepared in the laboratory and are based on the principle of application of a composite material directly to the prepared tooth surface in the dental clinic. Indirect laminate veneers may be produced from composite materials or ceramics, which are cemented to the tooth with an adhesive resin. In this case report, direct composite laminate veneer technique used for three patients with esthetic problems related to fractures, discolorations and an old prolapsed restoration, is described and six-month follow-ups are discussed. As a conclusion, direct laminate veneer restorations may be a treatment option for patients with the esthetic problems of anterior teeth in cases similar to those reported here.

A scanning electron microscopic study of external root resorption in replanted dog teeth

Root resorption after replantation of mature permanent dog incisors was examined by scanning electron microscopy. Three groups consisting of three extracted teeth each were kept in a saline solution for 5, 30, and 120 min before replantation. The first group was replanted with the pulp intact. The second and third groups were replanted after root canal filling by Calciobiotic Root Canal Sealer. After 90 days, the teeth were extracted and the apical root surfaces were examined. Severe inflammatory root resorption was observed in the first (intact pulp) group. For the root canal filled teeth, the degree of root resorption was observed to be much less in those kept in saline for 30 min than in those kept for 120 min.

Comparison of apical sealing of two canal sealers between immediate versus delayed post space preparation

The effect of post space preparation on the sealing ability of a root canal filling is important because the sealer is crucial for preserving the apical seal. The question of how, when, and how much of the gutta-percha should be removed is a debate when preparing a post space. This study is aimed to compare the effect of immediate versus delayed post space preparation on the apical seal using AH Plus and EndoREZ sealers. Forty four single rooted teeth were prepared using the step-back technique and were obturated with combinations of gutta-percha/AH Plus and gutta-percha/EndoREZ using the lateral compaction technique. Four teeth were used as positive/negative controls. After the teeth were divided randomly into six groups, post spaces were prepared either immediately after filling or after storage of the obturated teeth in saline at 37°C for one week. The post space preparation procedure was performed using hot pluggers or Gates Glidden drills leaving a 5 mm of root canal filling in the apical part. Leakage was determined by a computerized fluidfiltration device. Immediate and delayed post space preparation of the gutta-percha/AH Plus groups had mean leakage values of 4.97 µl.cmH2O.min-1.10-4 and 4.94 µl.cmH2O.min-1.10-4, respectively. The respective mean leakage values of immediate and delayed post space preparation of the gutta-percha/EndoREZ groups were 4.97 µl.cmH2O.min-1.10-4 and 5.57 µl.cmH2O.min-1.10-4. The mean leakage value obtained in the positive control group was 398.16 µl.cmH2O.min-1.10-4, whereas there was no fluid filtration in the negative control group. Better sealing was achieved in the guttapercha/AH Plus delayed group in comparison to the other groups. Delayed post space preparation in the gutta-percha/EndoREZ group showed the highest percentage of leakage.

Fractographic analysis of ProTaper and Mtwo systems: Breakage and distortion in severely curved roots of molars

Aim: This study evaluated the distortion and fracture mode of ProTaper and Mtwo rotary instruments following their use in severely curved root canals in extracted human teeth. Materials and Methods: A total of 30 mesial canals of mandibular molars were allocated into two groups that were balanced in terms of angle and radius of curvature. Canals were prepared by either ProTaper or Mtwo systems. Each set of instruments was changed after the third canal. Longitudinal and fractographic examinations of the instruments were carried out by scanning electron microscopy. Images were evaluated according to distortion and mode of fracture. Chi-square analysis and Fisher′s exact test were carried out at a significance level of P < 0.05. Results: No significant difference was found between fracture and distortion percentage of ProTaper and Mtwo rotary instruments (P > 0.05). Fractographic analysis revealed that all of the Mtwo instruments demonstrated torsional failure and all but one of the ProTaper instruments (S1) showed torsional failure. Conclusion: Fractographic examination of the fractured surface revealed shear fracture was the predominant mode of failure. Root canal curvature was an essential parameter influencing the susceptibility of instruments to fracture.