Teeth In Experimental Groups Research Articles

Fracture strength and color stability of direct composite veneer using different materials

Aim: The purpose of this study was to compare the fracture resistance and color stability of three different restoration materials: Nano composite, flowable composite, and Nanohybid composite.
 Materials and Methods: 45 removed human maxillary premolar teeth for orthodontic treatment were chosen. The teeth were divided into three experimental groups, each consisting of fifteen teeth: Direct composite veneers constructed of Nano - composites were employed to fix the teeth in Group A. (Z350 XT, 3M, USA). Group B: Flowable composite was used to directly veneer teeth (G-aenial Universal flo GC, Japan). Group C: Direct composite veneers made of Nanohybid composite were used to reconstruct teeth (G-aenial GC, Japan). Each tooth in groups A, B, and C had a copyplast template made prior to preparation using a 1 mm thick vacuum-pressed polyethylene plastic template. Standard preparations (intra enamel) were made for all teeth in experimental groups using ceramic veneer set burs. By injecting flowable composite via a hole formed in a copyplast template, Group B is restored. In Groups A and C, the buccal third (Bucco-palatally) of the template was filled with restorative material using a plastic tool before being positioned on the tooth and squeezed until it made contact with the unprepared tooth surface. All specimens' baseline colors were assessed using a spectrophotometer (Vita Easyshade, Ivoclar VivadentAG, Schaan, Liechtenstin). After baseline color measurement, each group of laminate veneers were subjected to immersion solutions (Tea bags, Lipton). Each specimen's color values were once again measured with the same spectrophotometer,
 
 and the color change values (ΔE) were computed. Using a universal testing equipment, the fracture strength was evaluated.

Evaluation and comparison of efficacy of different storage media in maintaining the viability of periodontal ligament cells-in vitro study

Aim: Aim of the study is evaluate the efficacy of HBSS, Green tea extract and Aloe Vera gel as storage media in maintaining the viability of periodontal ligament cell. Material and Method: Fifty- five human teeth with closed apices and with apparently normal periodontium were extracted as atraumatically as possible for orthodontic reasons were collected for study. Teeth were randomly divided into positive control group, negative control group, three experimental group. Teeth in experimental groups were dried for 30 minutes (including time taken for curetting coronal PDL cells), followed by a 45-minute immersion in one of the three storage solution groups. The teeth in positive control group after extraction was immediately treated with collagenase. The teeth in negative control group were bench- dried for 8 hours, with no follow- up storage solution time, and then placed in the collagenase. Result: HBSS is the best medium for the maintaining the viability of the PDL Cells.But easier availability and cost effectiveness, GTE and Aloe Vera Gel can be advocated as a viable storage medium. Conclusion: It can be concluded that GTE and Aloe Vera Gel can be advocated as a viable storage medium.

Incidence of dentinal defects during root canal preparation with hand files using different irrigants: An in vitro study.

Introduction:The purpose of this in vitro study was to compare the incidence of dentinal defects during root canal preparation with hand files using different irrigants.Materials and Methods:A total of 120 extracted mandibular incisors were randomly divided into onecontrol group and five experimental groups (n = 20) depending on the irrigant used. Biomechanical preparation was not done in control group. Teeth in experimental groups were prepared with hand K-files to a master apical file #35 with 1-mm increments step-back up to #50. In Group 2, saline was used as an irrigant. In Groups 3, 4, 5, and 6, 3% sodium hypochlorite (NaOCL), SmearClear, 17% ethylenediaminetetraacetic acid (EDTA), and 2% chlorhexidine (CHX), respectively, were used as an irrigant. Specimens were sectioned perpendicular to the long axis at 3, 6, and 9 mm from the apex. Sections were observed under a digital stereomicroscope at 30× magnification. Two-tailed t-test was used for statistical analysis.Results:There was a statistically significant difference between the six groups. Group 5 (17% EDTA) had the highest number of dentinal defects, followed by Group 3 (3% NaOCl), Group 4 (SmearClear), and Group 6 (2% CHX).Conclusions:17% EDTA causes more dentinal defects as compared to 3% NaOCl, SmearClear, 2% CHX, and saline.

Effect of glide path and apical preparation size on the incidence of apical crack during the canal preparation using Reciproc, WaveOne, and ProTaper Next systems in curved root canals: A stereomicroscope study.

This study evaluated the effect of creating a glide path and apical preparation size on the incidence of apical cracks during canal preparation in mandibular molar teeth with curved canals. One hundred and forty extracted teeth were used. The teeth were randomly assigned to one control group or six experimental groups (n = 20 per group) for canal preparation. No preparation was performed on teeth in the control group. In three of the six experimental groups, a glide path was not created; a glide path was created on the curved mesial canals of all teeth in the remaining three experimental groups. All teeth in experimental groups were then instrumented with the following systems: Reciproc, WaveOne (WO), and ProTaper Next (PTN). Digital images of the apical root surfaces of these teeth were recorded before preparation, after instrumentation with size 25 files, and after instrumentation with size 40 files. The images were then inspected for the presence of any new apical cracks and propagation. There was no significant difference between the experimental groups during canal preparation using size 25 files (p > 0.05). Reciproc and WO caused more new apical cracks than did PTN during canal preparation using size 40 files (p < 0.05). However, canal preparation using size 40 files did not cause propagation of existing cracks (p > 0.05). Performing a glide path prior to canal preparation did not change the incidence of apical crack during preparation. Additionally, increasing apical preparation size may increase the incidence of apical crack during canal preparation. SCANNING 38:585-590, 2016. © 2016 Wiley Periodicals, Inc.

Apical Extrusion of Intracanal Bacteria following use of Two Engine-driven Instrumentation Techniques: An in vitro Study.

The aim of the present study was to compare in vitro the amount of debris extruded apically from extracted teeth, using Twisted files and ProTaper rotary during two different instrumentation systems. Forty-five human single-rooted mandibular premolar teeth were randomly divided into three groups and contaminated with Enterococcus faecalis. The teeth in experimental groups were instrumented until reaching the working length with ProTaper rotary instruments and Twisted files with XSmart and XSmart Dual groups. Debris extruded from the apical foramen was collected into glass vials and the amount of bacteria was calculated. The data obtained were analyzed using Kruskal-Wallis one-way analysis of variance and Mann-Whitney U tests, with p = 0.05 as the level for statistical significance. The XSmart Dual group extruded comparatively lesser bacteria compared to the XSmart group. Lesser amount of bacterial extrusion was seen when Twisted files were used compared to the ProTaper files (p < 0.05). Under the circumstances of this in vitro study, it can be concluded that all instrumentation techniques produced measurable apical extrusion of debris. So, it is upon the practitioner to decide which system best fits their individual needs and their level of skill and experience that will provide the best possible endodontic care for our patients. The newer instrument designs, including noncutting tips, different cross sections, radial lands, and variable tapers, are better for the clinicians to improve working safety, to reduce the working time, and to create a greater flare within the preparations.

Apical sealing ability of bioceramic paste and mineral trioxide aggregate retrofillings: a dye leakage study.

Introduction: This study compared the apical sealing ability of a bioceramic based root canal repair filling material (iRoot FS) with mineral trioxide aggregate (MTA). Methods and materials: Forty single-canal teeth were prepared and randomly divided into two experimental groups ( n =18) and two control groups ( n =2). Teeth in experimental groups were retrofilled with either MTA or iRoot FS. After setting of the retrofillings, all roots were exposed to 0.2% Rhodamine B solution for 48 h and were then washed for 12 h before longitudinal sectioning. The extent of dye penetration was measured under fluorescence microscope. Results: The mean leakage values in MTA and iRoot FS samples were 35.63 and 35.15 µm, respectively. There was no significant differences between the two materials in this regard ( P =0.584). Conclusion: According to dye leakage results, iRoot FS had similar apical sealing ability to MTA and might be considered as a promising root-end filling material.

Comparison of the Initial Repeated Bond Strength among Three Orthodontic Bonding Systems

One of the problems that often occurred during orthodontic treatment is bracket failure. This is usually the result either of the patient’s accidentally, applying inappropriate forces to the bracket or of a poor bonding technique. Thus, a significant number of teeth have to be rebonded in an orthodontic practice. Objective: The aim of this study was to evaluate the in vitro initial repeated shear bond strength of the three adhesive systems at two and five minutes after placement of a bracket. Materials and Methods: The three bonding agent adhesives are System1+, Rely-a-bond, Unite. Two hundred and forty human premolar teeth were divided into two groups, a control and an experimental group. Each group was further divided into three subgroups for bonding brackets with the three different adhesives. Only the teeth in the experimental group were sequentially bonded and debonded two times with the same adhesive. The teeth in control and experimental groups were tested for shear bond strength (at two and five minutes after the bracket was bonded) with an Instron testing machine. Results: The studies were found that : (1) there were differences between the shear bond strength of each adhesive in the control and experimental group. Unite had the highest shear bond strength followed by Rely-a-bond and System1+ at two minutes and five minutes, (2) the experiment group ( rebonded brackets) had higher shear bond strength than control group and Unite had in significant difference (p&lt;0.05) of initial repeated bond strength with System1+ and Rely-a-bond at two minutes and five minutes and (3) there were mostly significant difference (p&lt;0.05) between repeated shear bond strength at two minutes and repeated shear bond strength at five minutes. Conclusion: There were significant difference of the initial repeated shear bond strength of each adhesive. The orthodontists should be aware of applying force for tooth movement into the repeated bonding brackets.

Comparison of the fracture resistance of reattached incisor tooth fragments using 4 different materials

To evaluate and compare the fracture resistance of reattached teeth using four different materials. 150 extracted human permanent maxillary incisors were randomly divided into five groups of 30 teeth each of one control and four experimental groups. Teeth in experimental groups were sectioned 2.5 mm from incisal edge and reattached using four different materials. The reattached teeth were subjected to evaluate fracture resistance. The mean fracture resistance of reattached teeth using resin modified glass ionomer cement, compomer, composite resin and dual curing resin cement was 8.10 ± 2.34, 11.15 ± 3.36, 17.11 ± 3.99 and 14.13 ± 3.71 kg respectively. Results showed highly significant difference between the groups ( P < 0.001). Fracture resistance of reattached teeth in the different groups varied from 24-51% of that for an intact tooth. Reattachment with composite resin provides highest fracture resistance ( P < 0.05). Reattachment with resin-modified glass ionomer cement was the weakest ( P < 0.05).

Efficacy of the enamel matrix derivative to induce cementogenesis in vital and endodontically treated teeth with osseous dehiscence defects

This experiment assessed the efficacy of the enamel matrix derivative (EMD) to regenerate cementum in vital and endodontically treated teeth with osseous dehiscence defects. Five adult female beagle dogs were used. Thirty maxillary teeth (bilateral maxillary canines and second and fourth premolars) were randomly divided into two experimental groups (groups A and B, containing 12 teeth each) and one control group (group C). Endodontic treatment was only performed on teeth in group A compared with teeth in groups B and C. Buccal osseous dehiscence defects were surgically created in teeth from all groups. Teeth in the experimental group were treated with the EMD, whereas the controls were not. After 5 months, the animals were sacrificed and block sections of the teeth in experimental and control groups were processed for histological analysis. Newly regenerated cementum was observed in all teeth in groups A and B. No cementum regeneration was observed in group C. There was a significant difference in cementum generation between the experimental and control groups (P < 0.001). EMD therapy induces cementogenesis in vital and endodontically treated teeth with osseous dehiscence defects.

Effects of Nd:YAG laser on micro-tensile bond strength of single bond adhesive system for non-carious sclerotic dentin

To investigate the effect of Nd:YAG laser on microtensile bond strength of single bond adhesive system for non-carious sclerotic dentin. Ten human molars with occlusal wearing were cut into equal halves (nearly 12 mm(2)), and randomly divided into experimental group and control group. The teeth in experimental group were processed with Nd:YAG laser (1 W, 10 Hz), and then applied with Scotchbond and filled with Z350 resin. In control group, the teeth were processed with single bond and filled with Z350 resin. The specimens were sectioned, and the microtensile bond strengths of each sample was tested by a universal testing machine. The bond strength of the experimental group [(26.11 ± 1.62) MPa] was significantly higher than that of the control group [(22.27 ± 2.16) MPa], P < 0.05. Stero-microscope examination indicated that most of the fractures occurred in dentin-resin interface. Nd:YAG laser can increase the microtensile bond strength of single bond adhesive system in non-carious sclerotic dentin.

Pulsed Nd:YAG laser-aided debonding for removing the metal brackets

To explore the possibility of pulsed Nd:YAG laser-aided debonding for removing orthodontic metal brackets and to compare the method with the conventional mechanical debonding method. Fifty healthy premolars extracted for orthodontic purpose were randomly divided into five groups (10 teeth in each group). There were four experimental groups and one control group. Every tooth was bonded with bracket. Laser was used to irradiate the teeth in experimental groups with different electric currents (13.0, 13.5, 14.0, 14.5 A). During the irradiation, the brackets received 4.9 N of force until the brackets off. The time needed for debonding and the temperature change of the pulp cavity were recorded. The teeth in control group were debonded using mechanical method. The adhesive remnant index (ARI) was calculated using stereomicroscope and imagetool software. All samples were examined with a scanning electron microscope. The time taken between the four groups were (67.70 ± 7.18), (35.90 ± 4.28), (24.90 ± 3.76), (6.90 ± 2.33) s, highly statistical difference was found in the time needed for debonding (P < 0.01). The temperature in the pulp cavity among the four groups were (20.97 ± 3.10), (12.75 ± 3.14), (8.99 ± 2.47), (2.91 ± 1.88)°C, and statistical differences were found in temperature change of the pulp cavity (P < 0.05). ARI of three experimental groups and the control group were (8.55 ± 5.02)%, (15.42 ± 7.37)%, (5.55 ± 3.79)%, (13.72 ± 6.69)%, and (74.36 ± 29.44)%. The enamel surface of the control group was coarse with deep scratchs. The enamel surface was smooth and clean in the experimental groups. Pulsed Nd:YAG laser-aided debonding for removing metal brackets was feasible. Laser-aided debonding was better than conventional mechanical debonding method. The method reduced the damage to the enamel surface.

Coronal microleakage in root canals obturated with lateral compaction, warm vertical compaction and guttaflow system.

Root canal obturation seals the root canal system to prevent re-entry and/or growth of microorganisms. The provision of an appropriate restoration to coronally seal the access cavity affects the success of endodontic treatment. The purpose of this study was to evaluate the coronal microbial leakage in root canals that were either filled by lateral compaction, GuttaFlow or warm vertical compaction. In this ex vivo study, 80 single-rooted human extracted teeth were randomly divided into three experimental groups (n=20) and two positive and negative control groups (n=10). The teeth in experimental groups were obturated with cold lateral compaction, GuttaFlow system or warm vertical compaction techniques. After sterilization of the whole system with gamma-ray, saliva leakage was tested using a split-chamber model. Specimens were monitored every 24 hours for 30 days. The data were analyzed using log-rank and Kaplan-Meier survival analysis tests. There were no significant differences in impeding saliva leakage between the three experimental groups (P>0.05). Under the conditions of this ex vivo study, it can be concluded that the sealing ability of cold lateral compaction, warm vertical compaction and GuttaFlow system was comparable.

Detection of Vertical Root Fractures of Different Thicknesses in Endodontically Enlarged Teeth by Cone Beam Computed Tomography versus Digital Radiography

Introduction This study was performed to compare the accuracy of cone beam computed tomography (CBCT) scans and digital radiography (DR) for detecting simulated vertical root fractures (VRFs) with different thicknesses in extracted human teeth. Methods Eighty teeth were endodontically prepared and divided into 4 groups, 3 experimental and 1 control. The teeth in experimental groups were artificially fractured and fixed together with different thicknesses of 0.2 mm (0.2-mm VRF group), 0.4 mm (0.4-mm VRF group), and smaller than 0.2 mm (crack group). Teeth in control group were kept intact. Three observers evaluated the DR and CBCT images in terms of accuracy for VRF detection. Results No significant differences in detection rate were noted among the observers ( P > .5). The overall accuracy for detecting VRFs was significantly higher for CBCT scans compared with DR ( P < .001). CBCT scans were more accurate in detecting 0.2-mm VRFs (70%) and 0.4-mm VRFs (90%) as compared with DR (43.3% and 60%, respectively). Conclusions The results of this study showed that CBCT scans are effective for detecting VRFs of different thicknesses.

Comparison of Various Root Planing Instruments: Hand and Ultrasonic—Standard Smooth and Diamond Coated: An in vivo Study

ABSTRACT Aim and objective This study was conducted to evaluate and compare the effectiveness of various root planing instruments, namely the curette, standard smooth ultrasonic tip and diamond coated ultrasonic tip under conditions of nonsurgical root debridement. Materials and methods A total of 20 incisors from 14 patients, with a pocket depth of 5 to 10 mm, indicated for extraction were selected for the study. Teeth selected were randomly assigned to one of the two groups, experimental group A and experimental group B. The proximal surfaces of teeth in experimental group A was instrumented with either Gracey curette or standard smooth ultrasonic tip and in experimental group B with either Gracey curette or diamond coated ultrasonic tip, randomly. Teeth were extracted without injuring the experimental area. The surface area under treatment was photographed at 10X and the percentage of residual calculus was evaluated. Teeth were processed for viewing under scanning electron microscope. Photomicrographs were graded for degree of cleanliness, Remaining Calculus Index (RCI) and Roughness and Loss of Tooth Substance Index (RLTSI) by an independent examiner. Results Percentage of residual calculus as evaluated using stereomicroscope did not show any statistical significance within the groups and among all the three instruments. Scanning electron microscopic assessment for the degree of cleanliness showed better cleanliness for curette compared to standard smooth ultrasonic tip. Remaining calculus was significantly higher for standard smooth ultrasonic tip compared to curette. Diamond coated ultrasonic tip showed greater roughness and loss of tooth substance. Conclusion Within the limits of this in vivo study, diamond coated ultrasonic tip removed a greater amount of root surface and created a rougher surface compared to the curette and standard smooth ultrasonic tip. The amount of root surface removed with diamond coated ultrasonic inserts suggests that they should be used with caution.

Crown cementing strategy for naval divers

Background: A large number of personnel working in hyperbaric environment such as divers and submariners during escape drills report to the out patient department with split teeth, displacement of restoration and pain during ascent after diving. These symptoms are probably attributable to dental barotraumas. Therefore, a need was felt to undertake a study in this area, with a specific interest for treating these patients. Methods: Sixty extracted single rooted premolar teeth were prepared and full cast crowns were cemented. Out of these, 20 were prepared with zinc phosphate, 20 with glassionomer and 20 with resin cement. After seven days of storage, each of the teeth in experimental group was pressure cycled 15 times to 3 atmospheres after which the force required to dislodge the crowns was tested on an Instron testing machine. Result: A significant difference was found (student's t test p value<0.01) between the force required to dislodge the crowns with zinc phosphate cemented control group (141.70 ± 38.62) and experimental group (16.92 ± 10.13). Similarly a significant difference was observed in the glassionomer cemented control group (184.33 ± 25.33) and experimental group (90.50 ± 34.07). On the other hand, no difference was found between the resin cemented control group (289.15 ± 81.48 ) and experimental (279.43±87.48) group. Conclusion: Within the limitations of this study and based on the results, it was concluded that environmental pressure cycling affected the retention of crowns cemented with zinc phosphate and glassionomer cement. Panavia resin cement used in this study appeared to be unaffected by environmental pressure cycling. On the basis of the results of this study, dental surgeons should consider cementing fixed prosthesis with resin cements for patients who are exposed to marked variations in environmental pressure, such as divers and submariners during escape drills.

Effect of Immediate and Delayed Post Preparation on Apical Microleakage by Using Methacrylate-based EndoREZ Sealer with or without Accelerator

The purpose of this study was to evaluate the effect of immediate and delayed post space preparation on the apical sealing ability of EndoREZ, a methacrylate-based dual-cured resin sealer, with or without accelerator. Fifty extracted human teeth were endodontically prepared and randomly divided into 6 groups. Teeth in experimental groups 1, 2, 3, and 4 (n = 10) were filled with resin-coated gutta-percha and either EndoREZ with accelerator (A+) or EndoREZ without accelerator (A−) by the lateral compaction technique. In group1 (A+) and group2 (A−), the post space was prepared immediately at the time of obturation. In groups 3 (A+) and 4 (A−), the post space was prepared after storage in 100% humidity at 37°C for 1 week. Groups 5 and 6 (n = 5) represented positive and negative control groups, respectively. Leakage was determined by computerized fluid filtration device. Complete leakage was observed in group 5, and no leakage was evident in group 6 ( P = 1.000). In experimental groups, mean apical microleakage values (μL/cmH 2O/min −1) were as follows: group 1, 2.77 ± 0.79 a; group 2, 2.88 ± 1.38 a; group 3, 19.95 ± 7.85 c; group 4, 6.20 ± 2.09 b (different letters indicate significantly different groups, P < .005). Immediate post space preparation achieved better sealing than delayed post preparation at the apical end, regardless of whether the EndoREZ accelerator was used. There was no significant difference between the (A+) and (A−) in immediate post space preparation. However, more leakage was found when using (A+) than (A−) in delayed post preparation. Under the conditions of this study, it was concluded that EndoREZ accelerator seems not to provide clinicians with any advantage for rapid transition from endodontic treatment to post-endodontic restorative procedures immediately after completion of root canal therapy.