Scanning electron microscopic evaluation of the influence of manual and mechanical glide path on the surface of nickel-titanium rotary instruments in moderately curved root canals: An in-vivo study.

AIM: The aim of this study was to evaluate the influence of manual versus mechanical glide path (GP) on the surface changes of two different nickel-titanium rotary instruments used during root canal therapy in a moderately curved root canal. MATERIALS AND METHODS: Sixty systemically healthy controls were selected for the study. Controls were divided randomly into four groups: Group 1: Manual GP followed by RaCe rotary instruments, Group 2: Manual GP followed by HyFlex rotary instruments, Group 3: Mechanical GP followed by RaCe rotary instruments, Group 4: Mechanical GP followed by HyFlex rotary instruments. After access opening, GP was prepared and rotary instruments were used according to manufacturer's instructions. All instruments were evaluated for defects under standard error mean before their use and after a single use. The scorings for the files were given at apical and middle third. STATISTICAL ANALYSIS USED: Chi-squared test was used. RESULTS: The results showed that there is no statistical difference between any of the groups. Irrespective of the GP and rotary files used, more defects were present in the apical third when compared to middle third of the rotary instrument. CONCLUSION: Within the limitations of this study, it can be concluded that there was no effect of manual or mechanical GP on surface defects of subsequent rotary file system used.

Comparative evaluation of the sealing ability of different obturation systems used over apically separated rotary nickel-titanium files: An in vitro study.

AIM: The study was designed to investigate the sealing ability of two obturation systems (cold laterally compacted gutta percha and Obtura II) over different apically separated rotary nickel-titanium files (RACE and K3 system) using dye extraction method. MATERIALS AND METHODS: Sixty-two mandibular premolars were divided into 2 groups of 30 teeth each, and 2 teeth served as negative controls. In Groups A and B, roots were prepared using RACE and K3 system, respectively, and were further subdivided into 4 subgroups. In subgroups A1, B1 and A2, B2 (n = 10 each), files were separated at 3 mm from the tip in apical 3(rd) of the canal. In subgroups A3, B3 and A4, B4 (n = 5), instruments were not separated. Subgroups A1, A3, B1, B3 and A2, A4, B2, B4 were obturated by lateral condensation method and Obtura II techniques, respectively. The sealing ability of the obturated specimens were tested using dye extraction method. The values for each group were recorded and analysis of variance (ANOVA), Student "t" test (two-tailed, independent), and Leven's test were performed. RESULTS: Group A1 showed significantly less leakage than B1. No statistical significant difference between Groups A2 and B2 and Groups A3 and B3, respectively, were observed. Group A4 showed significantly less leakage than B4. CONCLUSION: Groups obturated with Obtura II showed less leakage than the lateral condensation technique irrespective of presence or absence of fractured NiTi rotary system.

The prevalence of bilateral three-rooted mandibular first molar in Indian population.

INTRODUCTION: The purpose of the present study was to evaluate the prevalence of bilateral three-rooted mandibular first and second molars in Indian population. MATERIALS AND METHODS: A total of 215 patients were screened bilaterally for mandibular first and second molar and 430 samples of periapical radiographs were obtained. The gender, symmetry, and prevalence of three-rooted mandibular first and second molars were recorded. The correlation between left and right side occurrences and distribution were recorded and analysed using Z-test. RESULTS: The results showed that 33 teeth had three-rooted mandibular first molars, 16 male and 17 female (P=0.442). Overall, 21 teeth of right jaw and 12 teeth of left jaw (P=0.103) showed presence of an extra-root. The prevalence of three-rooted mandibular first molars was 7.67% and second molar was 0.23%. The bilateral frequency distribution was 3.72% for the first molar. There was no statistically significant difference between right side and left side mandibular molars. Also, gender did not show a significant relationship with this variant. CONCLUSION: The endodontic treatments of first mandibular molars require a careful clinical approach in Indian population as a high racial prevalence of 7.67% three-rooted molars was found. However, in the same population, 0.23% mandibular second molars had three roots.

A comparative analysis of restorative materials used in abfraction lesions in tooth with and without occlusal restoration: Three-dimensional finite element analysis.

OBJECTIVES: The present comparative analysis aimed at evaluating the mechanical behavior of various restorative materials in abfraction lesion in the presence and absence of occlusal restoration. MATERIALS AND METHODS: A three-dimensional finite-element analysis was performed. Six experimental models of mandibular first premolar were generated and divided into two groups (groups A and B) of three each. All the groups had cervical abfraction lesion restored with materials and in addition group A had class I occlusal restoration. A load of 90 N, 200 N, and 400 N were applied at 45° loading angle on the buccal inclines of buccal cusp and Von Mises stresses was chosen for analysis. RESULTS: In all the models, the values of stress recorded at the cervical margin of the restorations were at their maxima. Irrespective of the occlusal restoration, all the materials performed well at 90 N and 200 N. At 400 N, only low-shrink composite showed stresses lesser than its tensile strength indicating its success even at higher load. CONCLUSION: Irrespective of occlusal restoration, restorative materials with low modulus of elasticity are successful in abfraction lesions at moderate tensile stresses; whereas materials with higher modulus of elasticity and mechanical properties can support higher loads and resist wear. SIGNIFICANCE: The model allows comparison of different restorative materials for restoration of abfraction lesions in the presence and absence of occlusal restoration. The model can be used to validate more sophisticated computational models as well as to conduct various optimization studies.

An in vitro evaluation of fracture strength of endodontically treated teeth with simulated flared root canals restored with different post and core systems.

PURPOSE: The objective of this study is to evaluate the fracture strength and mode of failure of endodontically treated teeth with flared canals restored with two fiber reinforced systems (glass fiber and quartz fiber) and one base metal cast post and core system. MATERIALS AND METHODS: Forty five anterior teeth were decoronated at cemento-enamel junction and were endodontically treated. Post space was prepared and randomly divided into three groups according to post system. Specimens were loaded at 45° in a universal testing machine at a cross head speed of 0.5 mm/min until failure. The mode of failure was classified as repairable or non-repairable. RESULTS: Teeth restored with cast posts have fracture strength twice that of teeth restored with fiber posts. Fiber-reinforced posts failed at a certain compressive force but they were repairable unlike the non-repairable fracture seen with cast posts. CONCLUSION: The results of this study showed that, fracture strength and mode of failure in anterior teeth with flared canals varied according to the type of post used to support a crown.

Comparison of 2% chlorhexidine and 5.25% sodium hypochlorite irrigating solutions on postoperative pain: a randomized clinical trial.

AIM: To compare the levels of postoperative pain after cleaning and shaping of root canals using two different root canal irrigants for debridement. MATERIALS AND METHODS: Forty patients with irreversible pulpitis, pulp necrosis and non-vital teeth exhibiting acute apical periodontitis requiring root canal treatment were included. At random, canals were cleaned and shaped with the following protocols. 2% chlorhexidine solution in group I and 5.25% sodium hypochlorite solution in group II were used as an irrigants. Access cavities were closed with a sterile cotton pellet and cavit. The patients recorded degree of pain at various time intervals after cleaning and shaping on a visual analogue scale for 1 week. RESULTS: The mean pain score for group I was between 0.65 and 3.35 and for group II was between 0.95 and 4.50. There was significant difference in the pain level between the two groups only at 6 th hour postoperatively (P<0.05) and the pain was more in sodium hypochlorite group. CONCLUSIONS: More pain was present in teeth irrigated using 5.25% sodium hypochlorite when compared to that in teeth irrigated using 2% chlorhexidine solution. Significant difference in pain level was present only at 6th hour postoperatively, and at all other periods (24 th hour, 4 th and 7 th days) there was no significant difference in pain level between the two groups.

Infinite to finite: an overview of finite element analysis.

The method of finite elements was developed at perfectly right times; growing computer capacities, growing human skills and industry demands for ever faster and cost effective product development providing unlimited possibilities for the researching community. This paper reviews the basic concept, current status, advances, advantages, limitations and applications of finite element method (FEM) in restorative dentistry and endodontics. Finite element method is able to reveal the otherwise inaccessible stress distribution within the tooth-restoration complex and it has proven to be a useful tool in the thinking process for the understanding of tooth biomechanics and the biomimetic approach in restorative dentistry. Further improvement of the non-linear FEM solutions should be encouraged to widen the range of applications in dental and oral health science.

The effect of one-step and multi-step polishing systems on surface texture of two different resin composites.

OBJECTIVE: The purpose of this in-vitro study was to evaluate the surface roughness of two direct resin composites polished with one-step and multi-step polishing systems. MATERIALS AND METHODS: The resin composites examined in this study include minifill-hybrid composite Esthet-X (DENTSPLY/Caulk, Milford, DE, USA) and packable composite Solitaire II (Heraeus Kulzer, Inc., Southbend). A total of 42 discs (10 x 2 mm), 21 specimens of each restorative material were fabricated. Seven specimens per composite group received no polishing treatment and served as control. For each composite group, the specimens were randomly divided into two polishing systems: One-step PoGo (Dentsply/Caulk, Milford, DE, USA) and multi-step Super Snap (Shofu, Inc. Kyoto, Japan). Polishing systems were applied according to the manufacturer's instructions after being ground wet with 1200 grit silicon carbide paper. The surface roughness values were determined using a profilometer. RESULTS: Data was subjected to student's t test at a significance level of 0.05. The smoothest surfaces were achieved under Mylar strips in both the composite groups. Mean Ra values ranged from 0.09 to 0.3 mum for Esthet-X group and from 0.18 to 0.3 mum for Solitaire II with different polishing systems. The ranking of the order of surface roughness on the basis of the type of composite was as follows: Esthet-X < Solitaire II for PoGo system and Esthet-X = Solitaire II for Super Snap; and the ranking for the polishing system was: PoGo < Super Snap (P

Electrosurgery in aesthetic and restorative dentistry: A literature review and case reports.

Electrosurgery has been used in dentistry for more than half a century. There is abundant literature on electrosurgery dating back more than a century. During the past three decades, a substantial increase in minimally invasive surgery and microvascular surgery prompted greater use of electrosurgery. Although this surge in utilization has resulted in new applications, equipment features, problems and solutions, the use of electrosurgery in the field of restorative dentistry has remained relatively unchanged. The presence of conflicting and sometimes confusing information on electrosurgical wound healing in the dental literature is the most likely reason. This article briefly explains the literature review of electrosurgery and clinical application of electrosurgery in aesthetic and restorative dentistry.

The influence of different composite placement techniques on microleakage in preparations with high C- factor: An in vitro study.

OBJECTIVE: This study evaluated the marginal leakage around class-I cavity preparations restored with Nanofilled composite (Filtek Z-350 A2 shade, 3M ESPE, USA) and a self-etch adhesive (Xeno III, DENTSPLY/Caulk) using different composite placement techniques. MATERIALS AND METHODS: Standardized class-I cavities were prepared on 36 caries-free, extracted human premolars and were randomly assigned to three groups: (1) Horizontal incremental curing was done; each increment of thickness 1.5 mm was cured one after the other using curing unit (T-LED, Elca Technology, Italy). (2) Concave surface was obtained with a ball burnisher on the first increment and cured for 20 seconds; subsequently, the next increment was placed and similarly cured. (3) Cavities were filled with resin, short of the occlusal surface; two cuts (mesiodistal and buccolingual) were made through the condensed resin and cured for 20 seconds, followed by addition of resin in the gaps created by the cuts and additional curing for 20 seconds. The specimens were stored in distilled water for three months and then subjected to thermocycling, followed by immersion in 0.5% methylene blue dye for 24 hours. The teeth were sectioned longitudinally and evaluated for microleakage under stereomicroscope, and the scores obtained were analysed with Fisher Exact test and Kruskal-Wallis nonparametric test. RESULTS: There was no statistically significant difference among three groups. CONCLUSION: None of the techniques was capable of eliminating the microleakage in preparations with a high C-factor.