Osseoperception: An Implant Mediated Sensory Motor Control- A Review.

Osseointegration of dental implants has been researched extensively, covering various aspects such as bone apposition, biomechanics and microbiology etc however, physiologic integration of implants and the associated prosthesis in the body has received very little attention. This integration is due to the development of a special sensory ability, which is able to restore peripheral sensory feedback mechanism. The underlying mechanism of this so-called 'osseoperception' phenomenon remains a matter of debate. The following article reveals the histological, neurophysiologic and psychophysical aspects of osseoperception. A comprehensive research to provide scientific evidence of osseoperception was carried out using various online resources such as Pubmed, Google scholar etc to retrieve studies published between 1985 to 2014 using the following keywords: "osseoperception", "mechanoreceptors", "tactile sensibility". Published data suggests that a peripheral feedback pathway can be restored with osseointegrated implants. This implant-mediated sensory-motor control may have important clinical implications in the normal functioning of the implant supported prosthesis.

A Comparative Evaluation of Shear Bond Strength Between Two Commercially Available Heat Cured Resilient Liners and Denture Base Resin with Different Surface Treatments.

BACKGROUND: Soft denture liners are widespread materials used in prosthetic dentistry. Their mechanical properties have to meet several key requirements such as adequate bond to denture base resins in order to provide right function of masticatory system and oral hygiene. AIM: To evaluate and compare the shear bond strength between two commercially available liners and polymethyl methacrylate (PMMA) denture base resin with different surface treatments. MATERIALS AND METHODS: The two soft denture liners - Luci-Sof (silicone based liner) and Super-Soft (acrylic based liner) and a polymethyl methacrylate denture base resin (Trevalon) were chosen for the study. A total of 80 samples were made, 40 each for each of the two materials under investigation. The 40 samples were further divided into four groups, containing 10 samples each. Group I: Consisted of an untreated surface of polymethyl methacrylate which acted as the control. Group II: The surface of polymethyl methacrylate surface was sandblasted. Group III: The polymethyl methacrylate surface was treated with monomer. Group IV: The lining material was processed with acrylic resin dough. The samples after thermocycling for 500 cycles with temperatures from 5° ± 1°C to 55° ± 1°C and a 60 sec dwell time were subjected to shear loading on universal testing machine at crosshead speed of 20mm/sec. A Scanning Electron Microscope and stereomicroscope analysis of the bond interface between the liner and the denture base was conducted for all the groups of the two materials under study. STATISTICAL ANALYSIS: Data was analyzed using independent samples t-test, analysis of variance (ANOVA) and Post-Hoc Analysis. A significance level of α = 0.05 was used for statistical analyses. RESULTS: The bond strength was significantly different between Super- Soft and Luci-Sof (p<0.05) for all surface treatments. The scanning electron microscopy observations showed that the application of surface treatments modified the surface of the denture base resin. CONCLUSIONS: Super-Soft exhibited significantly higher bond strength than Luci-Sof. It was observed that Super-Soft when packed with the pre-polymerized samples produced highest bond strength values among all the groups for both the materials under study. The lowest bond strength was achieved for pre-polymerized samples when packed with Luci-Sof.

Student apathy for classroom learning and need of repositioning in present andragogy in Indian dental schools.

BACKGROUND: In the world of technology, when today's student is approaching the on-line /distance learning in the open universities and doing on-line self-assessment, the classroom learning is vanishing slowly. Globally, teachers are taking efforts to improve the pedagogy by implementing effective methods to retain the classroom teaching and student attendance. The present study aims at shedding some light on the need of changing the adult education strategies (andragogy), which can effectively improve the student attendance for lectures. METHODS: It is an observational study, and the conceptual framework of it is based on beliefs, opinions and personal experiences of the respondents. Triangulation method is used for collecting the data. The data is achieved from three groups of concerned population who could provide valid results to support the study. It is collected by interviewing 10 senior faculty members who are/were the 'education experts' in the universities, while the main concerned groups of present educational stream, i.e. 'institution-teachers' and the 'students', were given questionnaires. 570 teacher respondents and 200 student respondents are the main participants of this study. RESULTS: As per data, it has been observed that senior faculty (90%) and students (93.25%) feel need of student motivation more than the institutional teachers (52.44%). P-values were obtained using Chi-Square test for testing the significance of difference between agreement and disagreement for a specific question. CONCLUSIONS: In India, Universities have already sensed the need of 'teacher development programmes'. But teachers in dental colleges, demand more efforts to be taken by universities and managements in this regard and expect better educational policies to give them accessibility to prove themselves.

Force-frequency relation in frog-ventricle is dependent on the direction of sodium/calcium exchange in diastole.

AIM: Force of contraction increases with stimulus-frequency in mammalian and amphibian hearts under control conditions. Here, we have analysed the mechanism of the force-frequency relation (FFR) in frog-ventricle. METHODS: Circular strips of frog-ventricle were subjected to field-stimulation with frequencies in the range 0.03-0.2 Hz and force recorded on a chart-recorder. In another protocol, varying rest-periods were imposed while the preparation beat steadily at 0.2 Hz and the effect of rest on post-rest beat amplitude was noted. RESULTS: Under control conditions, a positive FFR and a rest-induced decay of contraction amplitude (RID) were seen in the frequency range 0.03-0.2 Hz. With cadmium, nifedipine, nickel (40 micromol L(-1)), ryanodine and adrenaline (all drugs at 10 micromol L(-1) concentration, except nickel), the positive FFR and RID seen under control conditions persisted. When the bathing solution contained ouabain (10 micromol L(-1)) or low external sodium (40 mmol L(-1)), or high external calcium (5 mmol L(-1)), the FFR turned negative in the frequency range stated above and there were rest-induced potentiations (RIP). CONCLUSION: When the conditions favour a net leak of calcium in diastole from intracellular stores via the calcium-extrusive mode of sodium-calcium exchanger (NCX), FFR is positive. An increase in frequency lessens the diastolic interval and therefore the diastolic calcium leak, thereby augmenting force. On the other hand, interventions which favour the calcium-acquisitive mode of NCX during diastole, changed the pattern of RID to RIP and converted FFR from positive to negative. With net diastolic calcium uptake, there is better store-filling and therefore higher force at lower frequencies.