Cone-beam computed tomographic evaluation to estimate the prevalence of palatogingival groove in the maxillary anterior teeth and its radiographic characteristics: An institutional retrospective study

Aim

The purpose of the study was to radiographically evaluate the prevalence of palatogingival groove (PG) in the East Indian population in the maxillary anterior teeth in different genders, its unilateral/bilateral presentation, classified based on its radiographic characteristics, to determine the prevalence of different types, which could help in future treatment planning.

Study Design

The design of the study was a retrospective study.

Materials and Methods

Analysis of 429 maxillary anterior teeth (144 central incisors, 145 lateral incisors, and 139 canines) in 72 cone-beam computed tomography scans was done (31 males and 41 females, mean age 27.3 ± 7.63). Demographic details of patients and characteristics of PG, i.e. location, extension, depth, and type, were recorded. The presence of alveolar bone loss and periapical pathology was noted.

Results

An overall prevalence of PG was found to be 2.33% (n = 10), with PG being detected in 2 (1.388%) central incisors, 8 (5.51%) lateral incisors, and 0 (0%) canines. Eight of the patients had a unilateral presence, while one patient reported with bilateral presence, implying a significantly higher predilection of unilateral occurrence (P = 0.02). The prevalence was found to be higher in females (n = 8). The teeth were categorized as either having Type I (6 teeth), Type II (3 teeth), or Type III (1 teeth). Three of the 10 PGs were present in the mesial, six in the mid-palatal, and one in the distal portion of the palatal surface.

Conclusions

The prevalence of PG in the maxillary incisors in this cohort is 2.33%. The maxillary lateral incisors are the most affected teeth. Unilateral presentation is more common.

Comparative evaluation of the shear bond strength of lithium disilicate veneers using one light-cure and two dual-cure resin cement: An in vitro study

Aim

The present in vitro study aimed to comparatively evaluate the shear bond strength (SBS) of one light-cure and two dual-cure resin cement to bond lithium disilicate veneers.

Materials and Methods

Thirty maxillary central incisors (n = 30) were procured and randomly divided into three groups of adhesive/resin cement systems, into groups of 10 each (n = 10); Group A: Adper Single Bond 2/RelyX Veneer Cement, Group B: Prime and Bond NT/Calibra, and Group C: Excite DSC/Variolink II. All the tooth samples were etched and respective bonding agent was applied. Similarly, all the laminate veneer specimens were etched, silanated, and treated with respective bonding agents before cementation with the respective resin cement. The SBS was measured in a universal testing machine with a cross-head speed of 1 mm/min.

Statistical Analysis

Data obtained were analyzed using the one-way analysis of variance and post hoc Tukey's test at a 5% significance level.

Results

The highest SBS was demonstrated by Group C (18.8 ± 0.92 Mpa), followed by Group B (18.4 ± 0.74) Mpa, and the least by Group A (17.4 ± 0.75 MPa). Significant differences were found between Group A, Group B, and Group C, respectively. However, Group B and Group C did not differ significantly from each other.

Conclusions

Dual-cure resin cement have higher SBS than the light-cure variants.

An evaluation of elution of leachable components from composite resins after light curing by light emitting diode and halogen light: An in vitro study

Objectives

The purpose of our study was to determine the amount of eluted triethyleneglycol dimethacrylate (TEGDMA) and to compare the eluted TEGDMA in different composite resins after light curing with conventional halogen light curing unit and light emitting diode (LED).

Materials and Methods

The present study was conducted on the two types of composite resins, which were divided equally into four groups - Group I: Denoted as Hybrid-LED, Group II: Denoted as Microhybrid-LED, Group III: Denoted as Hybrid-Halogen Group IV: Denoted as Microhybrid-Halogen. Polymerized specimens of hybrid and microhybrid composite resins were stored in air tight centrifuge tubes at 37°C for 24 h, then extract the monomers in high-performance liquid chromatography (HPLC) grade acetonitrile and water and incubated at 37°C for 24 h. All extracts were analyzed by HPLC. Eluted TEGDMA was detected by ultraviolet detector. The results obtained for TEGDMA were computed and analyzed using the one-way ANOVA and independent samples F-test at significance level 0.05.

Results and Conclusions

Elution of TEGDMA from all the samples of Group III (Hybrid-Halogen) was greatest and from Group II (Microhybrid-LED) was lowest. The sequence of TEGDMA elution was Group III > Group I > Group IV > Group II. From our results, we can conclude that the LED light curing unit may be more efficient than standard halogen light curing unit. The extractable quantities of composite resin components should be minimized. Furthermore, all ingredients of a dental composite should be declared by the manufacturers, in order to identify those substances in a product which may cause adverse side effects in patients and dental personnel.

Magnetoelectric Coupling through the Spin Flop Transition in Ni_{3}TeO_{6}

We combined high field optical spectroscopy and first principles calculations to analyze the electronic structure of Ni_{3}TeO_{6} across the 53 K and 9 T magnetic transitions, both of which are accompanied by large changes in electric polarization. The color properties are sensitive to magnetic order due to field-induced changes in the crystal field environment, with those around Ni1 and Ni2 most affected. These findings advance the understanding of magnetoelectric coupling in materials in which magnetic 3d centers coexist with nonmagnetic heavy chalcogenide cations.

Comparative Evaluation of the Etching Pattern of Er,Cr:YSGG & Acid Etching on Extracted Human Teeth-An ESEM Analysis

INTRODUCTION

Etching of enamel and dentin surfaces increases the surface area of the substrate for better bonding of the tooth colored restorative materials. Acid etching is the most commonly used method. Recently, hard tissue lasers have been used for this purpose.

AIM

The aim of the present study was to evaluate and compare the etching pattern of Er,Cr:YSGG and conventional etching on extracted human enamel and dentin specimens.

MATERIALS AND METHODS

Total 40 extracted non-diseased teeth were selected, 20 anterior and 20 posterior teeth each for enamel and dentin specimens respectively. The sectioned samples were polished by 400 grit Silicon Carbide (SiC) paper to a thickness of 1.0 ± 0.5 mm. The enamel and dentin specimens were grouped as: GrE1 & GrD1 as control specimens, GrE2 & GrD2 were acid etched and GrE3 & GrD3 were lased. Acid etching was done using Conditioner 36 (37 % phosphoric acid) according to manufacturer instructions. Laser etching was done using Er,Cr:YSGG (Erbium, Chromium : Ytrium Scandium Gallium Garnet) at power settings of 3W, air 70% and water 20%. After surface treatment with assigned agents the specimens were analyzed under ESEM (Environmental Scanning Electron Microscope) at X1000 and X5000 magnification.

RESULTS

Chi Square and Student "t" statistical analysis was used to compare smear layer removal and etching patterns between GrE2-GrE3. GrD2 and GrD3 were compared for smear layer removal and diameter of dentinal tubule opening using the same statistical analysis. Chi-square test for removal of smear layer in any of the treated surfaces i.e., GrE2-E3 and GrD2-D3 did not differ significantly (p>0.05). While GrE2 showed predominantly type I etching pattern (Chi-square=2.78, 0.05<p>0.10) and GrE3 showed type III etching (Chi-square=4.50, p<0.05). The tubule diameters were measured using GSA (Gesellschaft fur Softwareentwicklung und Analytik, Germany) image analyzer and the 't' value of student 't' test was 18.10 which was a highly significant result (p<.001). GrD2 had a mean dentinal tubule diameter of 2.78μm and GrD3 of 1.09μm.

CONCLUSION

The present study revealed type I etching pattern after acid etching, while type III etching pattern in enamel after laser etching. The lased dentin showed preferential removal of intertubular dentin while acid etching had more effect on the peritubular dentin. No significant differences was observed in removal of smear layer between the acid etched and lased groups. Although diameter of the exposed dentinal tubules was lesser after lased treatment in comparison to acid etching, further long term in vivo studies are needed with different parameters to establish the usage of Er,Cr:YSGG as a sole etching agent.

An ex-vivo comparative study of root-end marginal adaptation using grey mineral trioxide aggregate, white mineral trioxide aggregate, and Portland cement under scanning electron microscopy

Context:

Where nonsurgical endodontic intervention is not possible, or it will not solve the problem, surgical endodontic treatment must be considered. A major cause of surgical endodontic failures is an inadequate apical seal, so the use of the suitable substance as root-end filling material that prevents egress of potential contaminants into periapical tissue is very critical.

Aims:

The aim of the present ex-vivo study was to compare and evaluate the three root-end filling materials of mineral trioxide aggregate (MTA) family (white MTA [WMTA], grey MTA [GMTA] and Portland cement [PC]) for their marginal adaptation at the root-end dentinal wall using scanning electron microscopy (SEM).

Materials and Methods:

Sixty human single-rooted teeth were decoronated, instrumented, and obturated with Gutta-percha. After the root-end resection and apical cavity preparation, the teeth were randomly divided into three-experimental groups (each containing 20 teeth) and each group was filled with their respective experimental materials. After longitudinal sectioning of root, SEM examination was done to determine the overall gap between retrograde materials and cavity walls in terms of length and width of the gap (maximum) at the interface. Descriptive statistical analysis was performed to calculate the means with corresponding standard errors, median and ranges along with an analysis of variance and Tukey's test.

Results:

The least overall gap was observed in GMTA followed by PC and WMTA. While after statistically analyzing the various data obtained from different groups, there was no significant difference among these three groups in terms of marginal adaptation.

Conclusion:

GMTA showed the best overall adaptation to root dentinal wall compared to PC and WMTA. Being biocompatible and cheaper, the PC may be an alternative but not a substitute for MTA.

Comparative evaluation of different forms of calcium hydroxide in apexification

Background:

One out of every two children sustains a dental injury most often between 8 and 10 years of age. Majority of these teeth subsequently become non-vital and most often with immature apex. Management of these teeth is an enormous challenge for lack of apical stop. Calcium hydroxide in various formulations has maximum literature support in favor of successful apexification or induced apical closure.

Aim:

The aim of the following study is to determine the efficacy of calcium hydroxide in a different formulation to induce apexification.

Materials and Methods:

The present study was undertaken on 51 children of 8-10 years of age (both sexes) at Dr. R Ahmed Dental College and Hospital from April 2006 to March 2007. All children had one or two maxillary permanent central incisor (s), non-vital and apices open. In all the cases, apexification was attempted with either calcium hydroxide mixed with sterile distilled water, or calcium hydroxide plus iodoform in methyl cellulose base, or calcium hydroxide plus iodoform in polysilicone oil base. The success of apexification was determined on the basis of clinical and radiographic criteria.

Results:

In the pre-operative asymptomatic cases (72.55%), failure occurred in only 5.45% cases and pre-operative symptomatic cases failure rate was as high as 35.71%. Success rate was 94.6% in cases with narrow open apices, whereas 64.28% in wide open apices. In cases with pre-existing apical radiolucencies, successful apexification occurred in 63.63% and success rate was 92.5% in the cases without pre-existing apical radiolucencies. Average time consumed for apexification was minimum with calcium hydroxide plus iodoform in polysilicone oil base.

Conclusion:

The overall success rate observed to be 86.27%, which is in close proximity to the findings of most of the previous studies across the globe.

Comparative evaluation of the efficacy of different irrigants including MTAD under SEM

Context:

During biomechanical preparation, a smear layer is formed which occludes the openings of dentinal tubules and disfavors the penetration of irrigants. Hence, such layers should be removed. It becomes more challenging when we approach the apical third of the root canal.

Aim:

The aim was to compare the efficacy of different irrigants including ethylenediaminetetraacetic acid (EDTA), EDTA along with ultrasonication, citric acid, and mixture of tetracycline isomer, an acid, and a detergent (MTAD) as final irrigants where sodium hypochlorite (NaOCl) was used in each experimental group during root canal preparation with special emphasis on the apical third.

Settings and Design:

Forty-five human upper anterior teeth were selected and divided into one control group (group 1) and four experimental groups (group 2 to group 5), each containing nine teeth. All the four experimental groups were irrigated with 5.25% NaOCl solution during preparation, whereas test irrigants (5 mL) as the final solution used in each experimental group were 17% EDTA, 17% EDTA along with ultrasonication, 25% citric acid, and MTAD, respectively. The samples were prepared and observed under a scanning electron microscope (SEM). The photomicrographs were recorded and evaluated with a scoring system.

Statistical Analysis Used:

Data were analyzed using Kruskal-Wallis test and Dunn's test (P = 0.05).

Results:

None of the combined irrigants was found completely effective. All the test irrigants including MTAD worked well in the middle and cervical third, whereas MTAD showed excellent results in the apical third as compared to the other groups.

Healing of the periapical lesion in posterior teeth with mineral trioxide aggregate using orthograde technique - Two case reports

Conventional root canal treatment (RCT) of the teeth has long shown high success rate. However, the endodontic treatment of a pulpless tooth with periapical radiolucency of a considerable size always has a question of success. In modern days, surgical exploration is avoided, especially in the posterior teeth. These types of cases may be successfully managed by orthograde Mineral Trioxide Aggregate (MTA) placement in the apical third of the root followed by proper obturation. The objective of our present case reports was to evaluate the periapical pathology of posterior teeth clinically and radiographically by using MTA in orthograde way and avoiding traumatic surgical exploration. In the first case, the patient reported with intraoral sinus and pus discharge related to tooth #45. On radiograph, open apex (blunderbuss) was found along with periapical radiolucency. In the second case, the patient reported with pain and swelling related to tooth #26, having large periapical radiolucency related to the palatal canal. On vitality test, both the teeth responded negative, i.e., non-vital. Conventional RCT was planned in both the cases with orthograde MTA- Angelus (Angelus, Londrina, PR, Brazil) apical plug followed by the proper obturation with gutta-percha (G.P.), and after that the patients were kept on periodic follow-up and the outcome-based clinical and radiographic criteria were assessed. The post-obturation assessment at 1-month interval showed changes in the size of radiolucency with a gradual decrease, and after 6 months a remarkable decrease of radiolucency or the defect was almost filled with bone formation visible around the roots.

Observations of Co4+ in a higher spin state and the increase in the Seebeck coefficient of thermoelectric Ca3Co4O9

Ca3Co4O9 has a unique structure that leads to exceptionally high thermoelectric transport. Here we report the achievement of a 27% increase in the room-temperature in-plane Seebeck coefficient of Ca3Co4O9 thin films. We combine aberration-corrected Z-contrast imaging, atomic-column resolved electron energy-loss spectroscopy, and density-functional calculations to show that the increase is caused by stacking faults with Co4+-ions in a higher spin state compared to that of bulk Ca3Co4O9. The higher Seebeck coefficient makes the Ca3Co4O9 system suitable for many high temperature waste-heat-recovery applications.

Ab-initio adsorption study of chitosan on functionalized graphene: critical role of van der Waals interactions

We investigate the adsorption process of an organic biomolecule (chitosan) on epoxy-functionalized graphene using ab-initio density functional methods incorporating van-der-waals (vdW) interactions. The role of London dispersion force on the cohesive energy and conformal preference of the molecule is quantitatively elucidated. Functionalizing graphene with epoxy leads to weak hydrogen-bond interactions with chitosan. Binding energy values increase by over an order of magnitude after including vdW corrections, implying that dispersive interactions dominate the physisorption process. Conformal study show binding upto 30 kcal/mol when the molecule is oriented with the hydroxyl group approaching the functionalized graphene. Our study advances the promise of functionalized graphene for a variety of applications.

Effect of substrate on the atomic structure and physical properties of thermoelectric Ca₃Co₄O₉ thin films

The incommensurately layered cobalt oxide Ca(3)Co(4)O(9) exhibits an unusually high Seebeck coefficient as a polycrystalline bulk material, making it ideally suited for many high temperature thermoelectric applications. In this paper, we investigate properties of Ca(3)Co(4)O(9) thin films grown on cubic perovskite SrTiO(3), LaAlO(3), and (La(0.3)Sr(0.7))(Al(0.65)Ta(0.35))O(3) substrates and on hexagonal Al(2)O(3) (sapphire) substrates using the pulsed laser deposition technique. X-ray diffraction and transmission electron microscopy analysis indicate strain-free growth of films, irrespective of the substrate. However, depending on the lattice and symmetry mismatch, defect-free growth of the hexagonal CoO(2) layer is stabilized only after a critical thickness and, in general, we observe the formation of a stable Ca(2)CoO(3) buffer layer near the substrate-film interface. Beyond this critical thickness, a large concentration of CoO(2) stacking faults is observed, possibly due to weak interlayer interaction in this layered material. We propose that these stacking faults have a significant impact on the Seebeck coefficient and we report higher values in thinner Ca(3)Co(4)O(9) films due to additional phonon scattering sites, necessary for improved thermoelectric properties.

Non surgical perforation repair by mineral trioxide aggregate under dental operating microscope

Root perforation repair has historically been an unpredictable treatment modality, with an unacceptably high rate of clinical failure. Recent developments in the techniques and materials utilized in root perforation repair have dramatically enhanced the prognosis of both surgical and nonsurgical procedures. Mineral Trioxide Aggregate is a relatively new material that is being successfully used to repair perforations. Technological advancements such as the use of a Dental Operating Microscope for correction of these inevitable procedural errors are a major breakthrough in dentistry today. This article presents one clinical case of nonsurgical root perforation repair by Mineral Trioxide Aggregate, using the Dental Operating Microscope.

Management of intrusive luxation with immediate surgical repositioning

Intrusive luxation is one of the most severe forms of traumatic injuries in which the affected tooth is forced to displace deeper into the alveolus. As a consequence of this type of injury, maximum damage occurs to the pulp and all the supporting structures. This report presents a case of severe intrusive luxation of mature maxillary central and lateral incisor in a 40-year-old male. The intruded tooth was immediately repositioned (surgical extrusion) and splinted within hours following injury. Antibiotic therapy was initiated at the time of repositioning and maintained for 5 days. Pulp removal and calcium hydroxide treatment of the root canal was carried out after repositioning. Splint was removed 2 months later. Definitive root canal treatment with Gutta percha was accomplished at a later appointment. Clinical and radiographic examination 6, 12 and 24 months after the surgical extrusion revealed satisfactory progressive apical and periodontal healing.

Chromium III exposure inhibits brain Na+K+ATPase activity of Clarias batrachus L. involving lipid peroxidation and deficient mitochondrial electron transport chain activity

The present study elucidated the role of lipid peroxidation and diminished mitochondrial electron transport chain activity in partial dysfunction of brain Na+K+ATPase of Clarias batrachus exposed to chromium III ions. The fish were exposed to 10% and 20% of the derived 96 h LC50 value, 5.69 mg/L and 11.38 mg/L, respectively, and sampled on 20, 40 and 60 days. Exposure to chromium III on fish brain demonstrated an increased lipid peroxidation, production of protein carbonyl and reactive oxygen species and loss of protein thiol groups in synaptosomal fraction with decreased activity of Na+K+ATPase, partial inactivation of mitochondrial electron transport chain activity and energy depletion.

Assessment of the impact of pesticide residues on microbiological and biochemical parameters of tea garden soils in India

The main aim of this study was to assess the impact of pesticidal residues on soil microbial and biochemical parameters of the tea garden soils. The microbial biomass carbon (MBC), basal (BSR) and substrate induced respirations (SIR), beta-glucosidase activity and fluorescein diacetate hydrolyzing activity (FDHA) of six tea garden soils, along with two adjacent forest soils (control) in West Bengal, India were measured. The biomass and its activities and biochemical parameters were generally lower in the tea garden soils than the control soils. The MBC of the soils ranged from 295.5 to 767.5 micro g g(- 1). The BSR and SIR ranged from 1.65 to 3.08 mu g CO2-C g(- 1) soil h(- 1) and 3.08 to 10.76 micro g CO2-C g(- 1)h(- 1) respectively. The beta-glucosidase and FDHA of the soils varied from 33.3 and 76.3 micro g para-nitrophenol g(- 1) soil h(- 1) and 60.5 to 173.5 micro g fluorescein g(- 1)h(- 1)respectively. The tea garden soils contained variable residues of organophosphorus and organochlorine pesticides, which negatively affected the MBC, BSR, SIR, FDHA and beta -glucosidase activity. Ethion and chlorpyriphos pesticide residues in all the tea garden soils varied from 5.00 to 527.8 ppb and 17.6 to 478.1 ppb respectively. The alpha endosulfan, beta endosulfan and endosulfan sulfate pesticide residues in the tea garden soils ranged from 7.40 to 81.40 ppb, 8.50 to 256.1 ppb and 55 to 95.9 ppb respectively. Canonical correlation analysis shows that 93% of the total variation was associated with the negative impact of chlorpyriphos, beta and alpha endosulfan and endosulfan sulfate on MBC, BSR and FDHA. At the same time ethion had negative impact on SIR and beta-glucosidase. Data demonstrated that the pesticide residues had a strong impact on the microbial and biochemical components of soil quality.

Intradiploic haematoma behaving as a progressive mass lesion

A 17-year-old boy presented with a slowly growing right frontal bone swelling over an 8-year period. The swelling resulted in marked proptosis and reduced his visual acuity and eye movements. He was found to have clotting factor VIII deficiency. A chronic intradiploic haematoma as the cause of the swelling was a surprise finding.

Perception of an aggressor and his victim as a function of their relationship and retaliation

Two experiments, using a simple incident of aggression described in a passage, were conducted to study the evaluation of an aggressor (Study II) and his victim (Study I) as a function of their relationship. Both studies used a 2 (subjects' sex) × 2 (aggressor superior to victim vs aggressor subordinate to victim) × 2 (retaliating vs nonretaliating victim) factorial design, with 20 college students per cell as subjects ( N = 320). The nonretaliating victim was rated more positively than the retaliating victim on all dimensions. The aggressor tended to be more favorably judged when the victim was a superior rather than a subordinate, although this was not true of all conditions or of all dimensions.