Effect of Ultrasonic Instrumentation on the Retentive Strength of Zirconia Crowns Luted with Glass Ionomer and Adhesive Resin Cements With and Without Air Abrasion: An Invitro Study

INTRODUCTION: Great technical advancement in ultrasonic apparatuses over the last few years has permitted their increased use and dissemination among professionals of various specialties. This technological evolution was possible because of the piezoelectric properties of some crystals or metals. Accidental debonding of cemented crowns have been reported with the use of ultrasound. This occurs because in patients with fixed crowns the active tip of the ultrasound apparatus may come in contact with the border of the crown, altering the bond strength of the cement. AIM AND OBJECTIVE: The aim of this study is to analyse the retentive strength of zirconia crowns cemented with glass ionomer and adhesive resin cements subjected to air abrasion and ultrasonic instrumentation for various periods of time. JUSTIFICATION FOR STUDY: This study may decipher how much precaution should be taken while doing ultrasonic scaling on the cemented ceramic crowns and also as a way to analyse ultrasonic debonding of cemented crowns. METHODOLOGY: No of samples: 60 samples. Sixty recently extracted intact human maxillary & mandibular molar teeth was selected. Teeth preparation were standardized by giving 12◦ taper. Ceramic copings were manufactured using CAD/CAM. The sixty teeth was divided into two groups of 30 each (n=30). Each group was subdivided into two groups of 15 each (n=15). Each subdivided group was subgrouped into three subgroups of 5 each (n=5). After this procedure thirty Copings (n=30) were sandblasted using alumina 100μm. Cementation with GIC & self adhesive resin was performed according to the manufactures instructions. After this procedure, the specimens were submitted to ultrasonic instrumentation for different periods of time 0minute, 3minutes and 5 minutes. Retentive strength tests was performed with an Instron universal testing machine. Statistical analysis was performed using Post-hoc Tukey HSD analysis. STATISTICAL ANALYSIS: The data was subjected to statistical analysis by Multiple Comparison of mean and standard deviation of retentive strength of two cements used for the luting of zirconia copings to natural teeth within Groups A, B after various intervals of ultrasonic vibration using Anova followed by Post-hoc Tukey HSD analysis. RESULT: The comparison of these values using post hoc tukey analysis shows that there is a statistically significant difference in the tensile bond strength among these six groups. It can be clearly inferred that air abraded zirconia copings luted with dual cure self adhesive resin cement subjected to ultrasonic vibration for a period of 0 min ( Group C1) and vibration for a period of 3 minutes (Group C2) almost exhibit the same highest tensile bond strength. Zirconia copings without air abrasion luted using Glass ionomer cement subjected to ultrasonic vibration for a period of 5 minutes exhibit lowest tensile bond strength. (Group B3). CONCLUSION: The tensile bond strength of air abraded zirconia copings luted using dual cure self adhesive resin cement shows highest bond strength than other groups. It can be recommended that dual cure self adhesive resin cement can be used for the cementation of zirconia crowns subjected to air abrasion in clinical situations in order to achieve a more durable bond with the tooth structure and also debonding of crowns from the prepared tooth while conventional oral prophylaxis procedure by ultrasonic scaling can be minimized by using dual cure resin luting cement

Antifungal and Cytotoxic Activities of Some Marine Sponges Collected from the South East Coast of India

The present work describes the biological activities using the marine sponges collected from kanyakumari. The sponges are such as the Callyspongia diffusa, Echinodictyum gorgonoides, Callyspongia reticutis, Gelliodes cellaria, and Thalysias vulpine. It is revealed that the sponges showed the antifungal activity against the various fungal strains such as the Aspergillus niger, Pencillium notatum,and Candida albicans by using the agar well diffusion method. The sponge crude extracts seems to have effective cytotoxic property that was detected by Brine shrimp assay. Hence it is assumed that the marine sponges act as the vital source for the development of anticancer drugs

Estimation of Fano factor for oversquare HPGe detector

Fano factor is a quantity used to measure the departure of the observed variance in the number of charge carriers produced from that predicted using poison statistics. Fano factor varies with the detector type. In case of proportional counters and semiconductor detectors, it is substantially less than unity, whereas, for scintillator detectors, it would be unity. Even in case of semiconductor detectors, it varies with the type and the shape of the detector. Another source of fluctuations that gives the overall resolution of the detector is preamplifier noise. Oversquare coaxial HPGe detectors are a recent development in the field. Literature on the Fano factor of oversquare large volume coaxial detector is not available. In this work, the Fano factor and the electronic noise of an oversquare HPGe coaxial detector are estimated after optimizing the shaping parameters. The Fano factor for the oversquare HPGe detector is estimated as 0.1291 keV, which agrees with the ideal value of 0.13 by 99.98%. The preamplifier noise was found to be 0.048 keV which is 35% lesser than the reported value

Biomarkers as ecological indices in monitoring the status of market fish

Abstract Background Environmental contamination has become a major concern over the past few decades, drawing the attention of numerous researchers from both developed and developing nations. The aquatic system serves as the primary sink for the disposal of garbage, which has a negative impact on the aquatic environment and biota. The reality is that heavy metals cannot be totally removed from the ecosystem because they can bioaccumulate and grow in strength as they move up the food chain. Particularly heavy metals can build up in the tissues of aquatic animals, and as a result, tissue concentrations of heavy metals may be harmful to both human and animal health. Our study aimed to elucidate the possible use of biomarkers in monitoring and assessing the heavy metals contaminants among fresh water fish. Results From the present study, we conclude that glutathione peroxidase can be used as the bioindicator for nickel and iron contamination. Ultimately, these studies focus on measuring levels of pollution that may induce irreversible ecological changes to aquatic ecosystems. Till now the level of toxicity was moderate, and it was progressing toward the danger. Efforts can be made to control the activities that release pollutants unnaturally into the environment from both public and government so that the clean and clear environment can be maintained. Conclusions The work concludes that a multiparameter analysis is needed to assess and monitor the ecological status of the aquatic environment