A comparative evaluation of masticatory load distribution in different types of prosthesis with varying number of implants: A FEM analysis.

Aim: To identify the optimal number and position of implants to reduce stress concentration on the implant, denture, and attachment system for sustaining an overdenture prosthesis. Materials and methods: By incorporating one to eight indigenous implants with bar-type attachments, eight 3D finite element models of mandibular overdentures were created. All models received a 200 N vertical load, and the biomechanical characteristics of peri-implant bone were assessed. Result: The study observed that with a vertical load of 200 N, the maximum equivalent stress around peri-implant tissue in all models was within the physiological tolerance threshold of bone. The von Mises stress values ranged from 116.18 MPa to 536.7 MPa. Conclusion: The three-implant-supported overdenture model revealed superior peri-implant stress, stability, cost-effectiveness, and hygiene maintenance outcomes. Placing a third implant in the mid-symphysis region may offer a practical solution to reduce rotations in two-implant-supported overdentures.

Peri-implant stress distribution assessment of various attachment systems for implant supported overdenture prosthesis by finite element analysis - A systematic review.

Background: Various attachments like ball, bar-clip, magnetic attachments are used in implant supported overdentures. Finite Element Analysis (FEA) a newly innovated technology has been used in dental implantology to evaluate stress distribution patterns. There is little evidence available regarding the stress distribution in peri-implant region for implant supported overdentures. The purpose of the review was to generate scientific evidence on peri-implant stress distribution in FEA model with different types of attachments employed in implant supported overdentures. Materials and methods: Systematic review was conducted as per the Preferred Reporting Items for Systematic Reviews Guidelines and Meta-Analyses statement (PRISMA). A comprehensive search was undertaken by two reviewers from January 2020 to June 2020 with no year limits to published articles. Only in-vitro FEA studies were included. Following electronic databases were searched for published studies- PubMed, Web of Science. Characteristics of the studies tabulated and analysis of articles was done to compare different attachment systems. Results: Locator attachments showed better stress distribution than ball attachment system in all the studies but one. Two studies showed results in favour of ball attachment compared to bar-clip attachment system when stress was evaluated distal to the implants. No significant difference in terms of stress concentration could be generated between ball versus magnetic/equator versus locator attachment system due to less number of studies and conflicting results. Conclusion: Various studies showed different results due to heterogenicity in selected attachment systems and study designs. Locator attachments showed favourable stress distribution around peri-implant bone than other attachments.

A comparative evaluation of neurophysiological activity, active tactile sensibility and stereognostic ability of complete denture prosthesis, and implant-supported prosthesis wearer-A pilot study.

AIM: The study aimed to evaluate the effect of implant-supported prosthesis in completely edentulous participants in terms of osseoperception ability, neural activity, and stereognostic ability in comparison to removable prosthetic options. MATERIALS AND METHODS: A total sample of 18 patients, irrespective of gender and age were allocated into three groups according to the three-treatment protocol (upper and lower complete denture, upper complete denture opposing lower implant-retained overdenture, implant-supported fixed prosthesis in both arches). Four weeks after completion of the treatment procedure active tactile sensibility (ATS) was checked by using varying thicknesses (12, 40, 80, 100, 200 µ) of articulating foils and papers. Functional magnetic resonance imaging (fMRI) was performed to record neurophysiological activity in cerebral cortex in all the participants. Various forms of test pieces (heat cure acrylic resin) were used to evaluate stereognostic ability. Data regarding the neurophysiological activity were analyzed by using Krushkal-Wallis test and p ≤ 0.05 was considered to be statistically significant. Data from stereognostic ability test procedure and ATS were compared by using chi-squared test and p ≤ 0.05 was considered to be statistically significant. RESULTS: Statistically significant difference was found in between the articulating foils in terms of true negative responses as the foil thickness increased in participants wearing complete denture in both the arches (p = 0.004) and implant-supported fixed prosthesis in both the arches (p = 0.010). Participants in implant-supported fixed prosthesis group showed significantly more activation in primary motor cortex (right side), somatosensory cortex (left side), angular gyrus (both sides), temporal lobe (left) compared to other groups. No significant difference found in thalamus and premotor cortex region in between the participants of different groups. No statistically significant difference found in between the groups in terms of true responses identifying correct shapes. Mean number of correct responses in stereognostic ability test were 4.16 (83.33%), 3.5 (70%), 3.83 (76.66%) for participants of complete denture group, upper complete denture opposing lower implant retained overdenture group, and implant-supported fixed prosthesis group, respectively. CONCLUSION: Primary motor cortex, somatosensory cortex, and other regions of brain were diffusely activated in participants wearing implant-supported fixed prosthesis in both the arches. Less number of false responses were recorded in participants of implant-supported fixed prosthesis group and upper complete denture opposing lower implant-retained overdenture group in ATS test compared to participants wearing complete denture in both the arches.

Genetic Association of ACE2 rs2285666 Polymorphism With COVID-19 Spatial Distribution in India.

Studies on host-pathogen interaction have identified human ACE2 as a host cell receptor responsible for mediating infection by coronavirus (COVID-19). Subsequent studies have shown striking difference of allele frequency among Europeans and Asians for a polymorphism rs2285666, present in ACE2. It has been revealed that the alternate allele (TT-plus strand or AA-minus strand) of rs2285666 elevate the expression level of this gene upto 50%, hence may play a significant role in SARS-CoV-2 susceptibility. Therefore, we have first looked the phylogenetic structure of rs2285666 derived haplotypes in worldwide populations and compared the spatial frequency of this particular allele with respect to the COVID-19 infection as well as case-fatality rate in India. For the first time, we ascertained a significant positive correlation for alternate allele (T or A) of rs2285666, with the lower infection as well as case-fatality rate among Indian populations. We trust that this information will be useful to understand the role of ACE2 in COVID-19 susceptibility.

Semiprecision attachment: a connecting link between the removable and fixed prosthesis.

Oral rehabilitation of partially edentulous arches requires careful treatment planning before any prosthodontic intervention. The connection of the metal framework of fixed (fixed dental prosthesis (FPD)) and removable partial denture using adhesive attachments is a good alternative prosthetic option when solely fixed prosthesis (FPD or implant) cannot be used due to anatomical limitation. Attachments are the tiny interlocking devices that act as a hybrid link to join removable prosthesis to the abutment and direct the masticatory forces along the long axis of the abutment. This joint acts as a non-rigid stress breaker, which helps in distributing the occlusal load. Precision and semiprecision attachment have always been bordered by an aura of mystery due to technique sensitive procedure and lack of knowledge. The following case describes a combined contemporary and conventional approach and treatment sequence with the use of attachments for the rehabilitation of partially edentulous arches.

Identification and phylogenetic characterization of bovine ephemeral fever virus (BEFV) of Middle Eastern lineage associated with 2018-2019 outbreaks in India.

Bovine ephemeral fever virus (BEFV) is an evolving arbovirus reported across tropical, subtropical and temperate climatic zones globally. This study reveals prominent BEFV outbreaks in India, emerging annually during monsoons in subtropical areas accompanied by a congenial abundance of the vector population. PCR-based detection of viral genomic RNA in the blood samples collected during outbreaks of 2018-2019 for the first time confirmed the presence of BEFV in India. Phylogenetic analysis based on the glycoprotein gene of BEFV showed the current isolates to have high sequence homology with Middle Eastern lineage with nearly 97%, identity to Turkey (BEFV Ad12/TUR) and Israel (Israel 2006) isolates.

The peopling of Lakshadweep Archipelago.

The archipelago of Lakshadweep is considered as a stopover to the maritime route since ancient time. It is not very clear when the human first occupied these islands, however in the long history of the islands, the local legends suggest that Lakshadweep has been ruled by different kingdoms. To have a better understanding of peopling of Lakshadweep, we have analysed 557 individuals from eight major islands for mitochondrial DNA and 166 individuals for Y chromosome markers. We found a strong founder effect for both paternal and maternal lineages. Moreover, we report a close genetic link of Lakshadweep islanders with the Maldives, Sri Lanka and India. Most of the Lakshadweep islands share the haplogroups specific to South Asia and West Eurasia, except Minicoy Island that also shares haplogroups of East Eurasia. The paternal and maternal ancestries of the majority of island populations suggest their arrival from distinct sources. We found that the maternal ancestry was closer to South Indian populations, whereas the paternal ancestry was overwhelmed with the haplogroups, more common in the Maldives and North of India. In conclusion, our first genetic data suggest that the majority of human ancestry in Lakshadweep is largely derived from South Asia with minor influences from East and West Eurasia.

Reconstructing the population history of the largest tribe of India: the Dravidian speaking Gond.

This corrects the article DOI: 10.1038/ejhg.2016.198.

Reconstructing the population history of the largest tribe of India: the Dravidian speaking Gond.

The Gond comprise the largest tribal group of India with a population exceeding 12 million. Linguistically, the Gond belong to the Gondi-Manda subgroup of the South Central branch of the Dravidian language family. Ethnographers, anthropologists and linguists entertain mutually incompatible hypotheses on their origin. Genetic studies of these people have thus far suffered from the low resolution of the genetic data or the limited number of samples. Therefore, to gain a more comprehensive view on ancient ancestry and genetic affinities of the Gond with the neighbouring populations speaking Indo-European, Dravidian and Austroasiatic languages, we have studied four geographically distinct groups of Gond using high-resolution data. All the Gond groups share a common ancestry with a certain degree of isolation and differentiation. Our allele frequency and haplotype-based analyses reveal that the Gond share substantial genetic ancestry with the Indian Austroasiatic (ie, Munda) groups, rather than with the other Dravidian groups to whom they are most closely related linguistically.

Prevalence and Risk Factors for Oral Potentially Malignant Disorders in Indian Population.

Objective. To assess the prevalence of oral potentially malignant disorders and to determine the potential risk factors for its development in Indian population. Materials and Methods. This cross-sectional study was carried out on 1241 individuals in Indore, Madhya Pradesh. A questionnaire was designed to record information about sociodemographic characteristics, oral hygiene practices, dietary habits, and risk factors for oral potentially malignant disorders. Oral mucosal lesions were examined by a skilled person. Results. The overall prevalence of oral potentially malignant disorders was found to be 13.7% with oral submucous fibrosis (8.06%) found to be more common and erythroplakia (0.24%) found to be least prevalent. Results of Logistic Regression analysis showed that males (OR = 2.09, P value < 0.0001) who were ever consumers of tobacco (OR = 2.06, P value = 0.030) and areca nut chewing (OR = 2.64, P value = 0.004) were more likely to develop oral potentially malignant disorders compared to never consumers. Diabetic (OR = 2.21, P value = 0.014) and underweight individuals (OR = 2.23, P value = 0.007) were more likely to suffer from oral potentially malignant disorders. Conclusion. The study reinforces the association of tobacco and areca nut consumption with oral potentially malignant disorders. An association of oral potentially malignant disorders with diabetes and BMI was confirmed by this study.

Unravelling the distinct strains of Tharu ancestry.

The northern region of the Indian subcontinent is a vast landscape interlaced by diverse ecologies, for example, the Gangetic Plain and the Himalayas. A great number of ethnic groups are found there, displaying a multitude of languages and cultures. The Tharu is one of the largest and most linguistically diverse of such groups, scattered across the Tarai region of Nepal and bordering Indian states. Their origins are uncertain. Hypotheses have been advanced postulating shared ancestry with Austroasiatic, or Tibeto-Burman-speaking populations as well as aboriginal roots in the Tarai. Several Tharu groups speak a variety of Indo-Aryan languages, but have traditionally been described by ethnographers as representing East Asian phenotype. Their ancestry and intra-population diversity has previously been tested only for haploid (mitochondrial DNA and Y-chromosome) markers in a small portion of the population. This study presents the first systematic genetic survey of the Tharu from both Nepal and two Indian states of Uttarakhand and Uttar Pradesh, using genome-wide SNPs and haploid markers. We show that the Tharu have dual genetic ancestry as up to one-half of their gene pool is of East Asian origin. Within the South Asian proportion of the Tharu genetic ancestry, we see vestiges of their common origin in the north of the South Asian Subcontinent manifested by mitochondrial DNA haplogroup M43.