The Rayleigh-Taylor instability of a viscous fluid layer with viscosity stratification

The effects of viscosity stratification and surface tension on Rayleigh-Taylor (RT) instability in a finite thickness layer of an incompressible viscous fluid bounded above by a denser fluid and below by a rigid impermeable surface have been studied using linear stability analysis. A relation for the RT-instability growth rate is found by calculating the eigenvalues of the stability equation. It is shown that the shape of the dispersion curve is controlled by the ratio of surface tension to the stress gradient, with the layer thickness and the viscosity stratification affecting the rate of growth of the instability. The growth rate, infact, is shown to increase with increase in viscosity stratification and the thickness of the fluid layer. The results are shown to revert to those of the case of a viscous fluid layer in the absence of viscosity stratification

Lycopene and intralesional betamethasone injections in the management of oral submucous fibrosis

Aims and Objectives: This study was conducted to determine the efficacy of lycopene in the management of oral submucous fibrosis (OSMF) and to compare its efficacy with intralesional betamethasone injections. Materials and Methods: Forty-four patients were divided randomly into two groups. Group I subjects were treated with 10,000 mcg of lycopene (Lyconex) daily, in two equally divided doses, for two months. Group II subjects were given intralesional injections of betamethasone. Both the groups were assessed in terms of mouth opening and burning sensation. Results: A significant improvement in mouth opening was seen in both the groups and the improvement was better in Group I. The mean improvement in mouth opening in Group I was 37.62% (12 mm) at the end of the study, which was statistically highly significant and weekly evaluation revealed that this high significance was from the third week onward, and Group II patients (only intralesional steroids) showed an average improvement of 13% (3.9 mm) at the final follow-up visit. Conclusion: Lycopene (Lyconex) is better than intralesional betamethasone injections in improving mouth opening and decreasing burning sensation

The effects of transcutaneous electric nerve stimulation (TENS) on salivary flow: A study

Aim: This study was undertaken to evaluate the effectiveness of transcutaneous electric nerve stimulation (TENS) as a means of stimulating salivary function in healthy adult subjects. Materials and Methods: Fifty healthy adult subjects with no history of salivary gland disorder were enrolled in the protocol. The TENS electrode pads were placed externally on the skin overlying the parotid glands. Unstimulated saliva was collected for 5 min into graduated tubes. TENS unit was then activated and the stimulated saliva collected for an additional 5 min. Statistical Analysis Used: A paired "t" test was applied to look for statistically significant differences as a group between the amount of unstimulated and TENS-stimulated samples of saliva. Results: Forty-three out of 50 subjects demonstrated increased salivary flow when stimulated via the TENS unit. The mean unstimulated salivary flow rate was 0.354 ml/min (SD 0.19) and the mean stimulated salivary flow rate was 0.49 ml/min (SD 0.24). Statistical analysis of flow rates utilizing the paired t test demonstrated the difference to be statistically significant (P < 0.001). Conclusion: The TENS unit was effective in increasing the salivary flow in two-thirds of healthy adult subjects. A further study in a cohort of patients with salivary gland disorders is warranted

Odontoameloblastoma: A rare case with unusual presentation

The odontoameloblastoma (OA), also known as ameloblastic odontoma, is a very rare odontogenic tumor that is similar to ameloblastoma in its locally aggressive behavior. OA includes odontogenic ectomesenchyme in addition to odontogenic epithelium that resembles an ameloblastoma both in structure and in behavior. Its clinical presentation, however, often mimics the more innocuous odontoma, and hence, the recognition of its aggressive nature is commonly only ascertained after its histopathologic diagnosis following enucleation. This paper presents a rare case of OA with unusual clinical and radiological features

Correlation of blood glucose level in gingival crevicular blood and finger capillary blood using glucometer

Aim: The aim of the study was to assess the reliability of gingival crevicular blood (GCB) glucose level compared with finger capillary blood (FCB) glucose level using a glucose self-monitoring device (Contour ® TS). Materials and Methods: One hundred randomly selected patients with gingivitis (45 subjects) and periodontitis (55 subjects) were included in the study. The mean age of the study group subjects was 35.39 ± 11.97 years (range 17-70 years). The blood glucose values obtained from GCB elicited during routine periodontal probing and those of peripheral finger stick blood glucose were recorded using a glucose self-monitoring device (glucometer) during fasting and postprandial phases. Statistical analysis was done using Student′s "t" test and Karl Pearson′s product moment correlation. The regression analysis was then performed to compare the GCB and FCB blood glucose readings using the approach of Bland and Altman. Results: There was no statistically significant difference (t = 1.443, P = 0.152) between the fasting GCB and FCB glucose values, but it was significant during postprandial measurement (t = 6.893, P < 0.001). Pearson′s correlation showed a positive correlation between the two measurements (r = 0.893, P < 0.001). Bland-Altman regression analysis revealed sufficient agreement between the two values. Conclusion: The results suggest that GCB collected during diagnostic periodontal examination may be an excellent source of blood for glucometric analysis. Thus, it can be used as a chairside investigative procedure

Dental age estimation by Demirjian′s and Nolla′s method: A comparative study among children attending a dental college in Lucknow (UP)

Introduction: Estimation of age is an important aspect of forensic science. The assessment of age is useful in forensic odontology and in treatments plans of orthodontic and pedodontic patients. Aims and Objectives: The aim of the study was to determine dental age from orthopantomograph using Demirjian′s method and Nolla′s method. It was also to evaluate the interrelationship between chronological and dental age according to both these methods and to evaluate which technique was better. Materials and Methods: The study was conducted in the Department of Oral Medicine and Radiology of Babu Banarasi Das College of Dental Sciences (UP, Northern India). A total of 300 subjects (150 girls and 150 boys) of age group from 6 years to 15 years were enrolled. These subjects were grouped by a difference of 1 year into 10 groups (each group comprised of 30 subjects: 15 males and 15 females). For every individual included in the study a panoramic radiograph was taken, with standard parameters and adequate protective measures. Results: The results imply that Demirjian′s method is applicable to all age groups and for both genders with better accuracy than Nolla′s method, which had a limited utility in younger age group. Thus Demirjian′s method is a better method when compared to Nolla′s method in Northern Indian population

In vivo comparison of Kodak E-speed film and direct digital imaging system for assessment of interproximal bone loss

Aims: To evaluate the diagnostic accuracy of direct digital radiography as compared to a conventional radiographic film for the assessment of interproximal bone loss with intrasurgical measurements as the gold standard. Materials and Methods: A total of 100 patients, with untreated moderate-to-advanced periodontal disease, were included in the study. The presurgical radiographs were made using a Kodak E-speed film and a Dexis digital sensor simultaneously, for sites with interproximal bone loss. At the time of surgery, the distance from the cementoenamel junction to the bone defect (CEJ-BD) was measured for 331 interproximal defects. The radiographs were randomized and then linear measurements were taken for the same sites in both conventional and digital radiographs. Stastistical Analysis: Comparison between the conventional, digital, and intrasurgical measurements was done statistically using the Student′s t-test. The agreement and correlation among the methods was assessed using the weighted Kappa measure of agreement and Pearson′s correlation, respectively. Results: The results showed that the conventional (5.15 ± 2.19 mm) and digital analyzing techniques (5.13 ± 2.19 mm) underestimated the interproximal bone loss, as compared to the intrasurgical measurements (6.07 ± 2.05 mm) (p < 0.001). The difference between conventional and digital radiographic methods was found to be statistically insignificant (p = 0.92). Conclusion: Under normal clinical use, the alveolar bone levels revealed on intraoral direct digital radiographs and Kodak E speed film were almost same. Therefore, the digital radiographic system can be routinely used in clinical practice as an alternative to conventional film