Multilocus sequence typing of Clostridium perfringens strains from neonatal calves, dairy workers and associated environment in India.

Clostridium perfringens is a globally recognized zoonotic pathogen. We report isolation and genotyping of C. perfringens from neonatal calves, dairy workers and their associated environment in India. A total of 103 fecal samples from neonatal calves, 25 stool swabs from the dairy workers and 50 samples from their associated environment were collected from two dairy farms. C. perfringens was detected in 26 out of 103 (25.2%) neonatal calf samples, 7 out of 25 (28%) human stool samples and 17 out of 50 (34%) environmental samples. C. perfringens type A strains were predominant in neonatal calves (24/26; 92.3%) and associated environment (15/17; 88.2%). In contrast, strains from dairy workers mostly belonged to type F (5/7; 71.4%), which also carried the beta2 toxin gene. Seventeen strains were analyzed by multilocus sequence typing (MLST) for studying genotypic relationship along with 188 C. perfringens strains available from public databases. A total of 112 sequence types (STs) were identified from 205 C. perfringens strains analyzed. A Clonal complex (CC) represented by three STs (ST 98, ST 41 and ST 110) representing predominantly type F (18/20 strains) were mostly associated with human illnesses. Among predominant STs, ST 54 was associated with enteritis cases in foals and dogs and ST 58 associated with necrotic enteritis in poultry. Seventeen Indian strains were assigned to 13 STs. Genetic relatedness among strains of calves, dairy worker and associated environments indicate inter-host transfers and zoonotic spreads.

Expression and purification of an immunogenic SUMO-OmpC fusion protein of Salmonella Typhimurium in Escherichia coli.

Salmonella is found to be a major causes of food borne diseases globally. Poultry products contaminated with this pathogen is one of the major sources of infections in humans. Outer membrane protein C (OmpC) of Salmonella Typhimurium is a promising DNA vaccine candidate to mitigate Salmonella infection in poultry. However, the large-scale production of bioactive recombinant OmpC (rOmpC) protein is hindered due to the formation of inclusion bodies in Escherichia coli. The objective of this work was to attain high level expression of rOmpC protein, purify and evaluate its functional properties. The ompC gene was optimized and fused with small ubiquitin-related modifier (SUMO) gene for high level expression as soluble protein. The fusion protein with ~58 kDa molecular weight was observed on SDS-PAGE gel. The expression levels of rOmpC fusion protein reached maximum of 38% of total soluble protein (TSP) after 8 h of 0.2% rhamnose induction. Protein purification was carried out using nickel nitrilotriacetic acid (Ni-NTA) purification column. Western blot were performed to analyse expression and immunoreactivity of rOmpC fusion protein. The results indicate that SUMO fusion system is ideal for large scale production of functional rOmpC fusion protein expression in E. coli.

Occurrence, antimicrobial susceptibility patterns and genotypic relatedness of Salmonella spp. isolates from captive wildlife, their caretakers, feed and water in India.

Occurrence of Salmonella spp. in captive wild animal species in India is largely unknown. The purpose of this study was to determine the occurrence of different Salmonella serotypes, antimicrobial resistance patterns and genotypic relatedness of recovered isolates. A total of 370 samples including faecal (n = 314), feed and water (n = 26) and caretakers stool swabs (n = 30) were collected from 40 different wild animal species in captivity, their caretakers, feed and water in four zoological gardens and wildlife enclosures in India. Salmonellae were isolated using conventional culture methods and tested for antimicrobial susceptibility with the Kirby-Bauer disc diffusion method. Salmonella isolates were serotyped and genotyping was performed using enterobacterial repetitive intergenic consensus (ERIC) PCR and 16S rRNA sequencing. Animal faecal samples were also subjected to direct PCR assay. Salmonella was detected in 10 of 314 (3.1%) faecal samples by isolation and 18 of 314 (5.7%) samples by direct PCR assay; one of 26 (3.8%) feed and water samples and five of 30 (16.7%) caretakers stool swabs by isolation. Salmonella was more commonly isolated in faecal samples from golden pheasants (25%; 2/8) and leopard (10%; 2/20). Salmonella enterica serotypes of known public health significance including S. Typhimurium (37.5%; 6/14), S. Kentucky (28.5%; 4/14) and S. Enteritidis (14.3%; 2/14) were identified. While the majority of the Salmonella isolates were pan-susceptible to the commonly used antibiotics. Seven (43.7%; 7/16) of the isolates were resistant to at least one antibiotic and one isolate each among them exhibited penta and tetra multidrug-resistant types. Three S. Kentucky serotype were identified in a same golden pheasants cage, two from the birds and one from the feed. This serotype was also isolated from its caretaker. Similarly, one isolate each of S. Typhimurium were recovered from ostrich and its caretaker. These isolates were found to be clonally related suggesting that wildlife may serve as reservoir for infections to humans and vice versa. These results emphasise the transmission of Salmonella among hosts via environmental contamination of feces to workers, visitors and other wildlife.

Development and evaluation of isothermal amplification assay for the rapid and sensitive detection of Clostridium perfringens from chevon.

Loop-mediated isothermal amplification (LAMP) is a promising, simple, rapid and sensitive molecular detection method. In the present study, LAMP assay was developed for detecting Clostridium perfringens in chevon. Primers were designed to detect the cpa gene of C. perfringens. A panel of 19 bacterial strains, including 3 C. perfringens and 16 other strains, were included in this study to standardize and evaluate the LAMP assay. No false positive amplification was observed indicating 100% specificity of the assay. The detection limit of LAMP and conventional PCR in the DNA extracted from pure C. perfringens was 0.34 pg and 3.4 pg, respectively. This revealed that LAMP assay is 10 times more sensitive than conventional PCR. The sensitivity of the LAMP assay for the detection of C. perfringens in raw chevon was found to be 1.2 × 102 CFU/g after 6-h enrichment and 1.2 × 105 CFU/g without enrichment in artificial spiking studies. Improved C. perfringens detection of 12 CFU/g within 12 h was obtained proving that LAMP assay is significantly faster than traditional methods that take >2 d. The developed LAMP assay also detected the targeted organism in clinical and environmental samples with the sensitivity and specificity of 97% and 84%, respectively with Kappa agreement of 0.824 respects to PCR assay. This method shows immense potential for routine diagnosis and monitoring of C. perfringens in food, environment and clinical samples. This is the first report in which the LAMP assay was optimized for the detection of C. perfringens in chevon.

Diversity of toxin-genotypes among Clostridium perfringens isolated from healthy and diarrheic neonatal cattle and buffalo calves.

The diversity of toxin-genotypes of C. perfringens in neonatal calves was determined in this study. A total of 682 fresh faecal samples comprising 559 healthy and 123 diarrheic neonatal calves (cattle and buffalo) were collected from various farms in Northern India. The samples were processed for isolation of C. perfringens and toxin-genotyping by multiplex PCR. The overall prevalence of C. perfringens was 37.2%. The most predominant toxin-genotype was type A (59.7%) and the least prevalent was type C. There was no association between toxin genotypes and diarrhea of cattle and buffalo neonatal calves (P > .05). Also, 38 (14.6%) and 16 (6.1%) isolates out of the 259 carried enterotoxin (cpe) and beta 2 toxin (cpb2) genes, respectively. Ten different toxin-genotypes were identified, and iota toxin gene was not detected in any of the sample.

Prevalence and molecular typing of Clostridium perfringens in captive wildlife in India.

The prevalence of Clostridium perfringens in captive wildlife in India has not been reported. The objective of the study was to determine the fecal prevalence of C. perfringens in captive wildlife in India. The prevalence in captive wild ruminants, non-ruminants, birds and caretakers were 34.1%, 36%, 22.5% and 6.7%, respectively. Toxinotyping of C. perfringens indicated that the predominant type was type A with a prevalence rate of 69.7%, followed by type A with cpb2 gene (28.3%) and type B (2.%).

Development and Evaluation of Simple Dot-Blot Assays for Rapid Detection of Staphylococcal Enterotoxin-A in Food.

The present study was aimed to develop and evaluate dot-blot assays for rapid detection of staphylococcal enterotoxin-A (SEA) in food. Dot blots were developed in two formats, indirect and sandwich utilizing mouse monoclonal anti-SEA and rabbit polyclonal anti-SEA antibodies. In indirect dot-blot format, recombinant SEA was directly coated on NCM dot-blot strip and detection was carried out by anti-SEA antibodies. In sandwich dot-blot format, SEA was trapped between anti-SEA capture and detection antibodies. Both the dot-blot assays exhibited a sensitivity of ~48 ng ml-1 when tested in different food matrices. The developed assays were highly specific as no cross-reactivity was detected with other classical staphylococcal enterotoxins, toxigenic bacteria and foodborne pathogens. Sensitivity and specificity of developed indirect and sandwich dot-blot assays with respect to PCR was found to be 100 and 99%, respectively. The results shows that the developed dot-blot assays can be used as rapid preliminary screening tests for detection of SEA in food or determining the toxigenic potential of staphylococci, especially in resource-limited settings.

Antimicrobial resistance and typing of Salmonella isolated from street vended foods and associated environment.

The present study was carried out to find out the occurrence and types of Salmonella present in street vended foods and associated environment, and their resistance pattern against various antibiotics. About 1075 street vended food and associated environment samples were processed for isolation and confirmation of different Salmonella spp. by targeting gene specific invA gene and serotype specific Sdf I, Via B and Spy genes by PCR. Selected Salmonella isolates were screened for antibiotic resistance by using Baeur-Kirby disk diffusion test. Out of 1075 samples, only 31 (2.88%) isolates could be amplified the invA gene of which 19 could be recovered from meat vendors; 8 from egg vendors while remaining 4 from milk vendors. Though, majority of Salmonella recovered from raw foods the ready-to-eat food like chicken gravy and rasmalai also showed its presence which pose a serious public health threat. Overall, 19, 6 and 1 isolates of S. Typhimurium, S. Enteritidis and S. Typhi could be detected by PCR while remaining 5 isolates could not be amplified suggesting other type of Salmonella. Selected Salmonella isolates were completely resistance to Oxacillin (100%) followed by Cefoxitin (30.43%) and Ampicillin (26.10%). Thus, it is observed that the street vended foods of animal origin and associated environment play an important role in transmission of food borne pathogens including Salmonella.

Contribution of protein isoaspartate methyl transferase (PIMT) in the survival of Salmonella Typhimurium under oxidative stress and virulence.

The enteric pathogen Salmonella Typhimurium (ST) survives inside the oxidative environment of phagocytic cells. Phagocyte generated oxidants primarily target proteins and modify amino acids in them. These modifications render the targeted proteins functionally inactive. Conversion of Asp to iso-Asp is one of the several known oxidant mediated amino acids modifications. By repairing iso-Asp to Asp, protein-isoaspartyl methyltransferase (PIMT) maintains the activities of proteins and thus helps in cellular survival under oxidative stress. To elucidate the role of PIMT in ST survival under oxidative stress, we have constructed a pimt gene deletion strain (Δpimt strain) of ST. The Δpimt strain grows normally in various culture media in vitro. However, in comparison to wild type ST, the Δpimt strain is found significantly (p<0.001) more susceptible to H2O2 and hypochlorite (HOCl). Further, the Δpimt mutant strain shows hypersusceptibility (p<0.001) to INF-γ stimulated macrophages. This susceptibility is reversed by pharmacological inhibition of reactive oxygen species (ROS) but not reactive nitrogen species (RNS) production. Further, plasmid based complementation enhances the survival of Δpimt mutant strain against oxidants in vitro and also inside the macrophages. In mice model, the LD50 for wild type ST and mutant Δpimt has been 1.73×10(4) and 1.38×10(5), respectively. Further, the mutant strain shows reduced dissemination to spleen and liver in mice. Following infection with a mixture of wild type ST and the Δpimt mutant (co-infection experiment), we recover significantly (p<0.001) less numbers of mutant bacteria from the spleen and liver of mice.

Development of loop-mediated isothermal amplification test for the diagnosis of contagious agalactia in goats.

Contagious agalactia is a highly infectious disease affecting sheep and goats, mainly caused by Mycoplasma agalactiae. Although various tests are available for diagnosis of contagious agalactia, none of them is credited with the capacity to provide rapid and cost-effective diagnosis. This article reports the development of loop-mediated isothermal amplification (LAMP) test targeting the p40 gene of M. agalactiae, for the diagnosis of classical contagious agalactia. Optimum amplification was obtained at 58 °C in 70 min. The developed test was found to be 100-fold more sensitive than PCR and detected up to 20-fg level of DNA. The test was also superior to conventional PCR in detecting from artificially contaminated milk, i.e. 10(4)-fold more sensitive. The developed LAMP test could detect up to 10 cfu/ml of artificially contaminated milk, indicating its potential for being developed as a field test for rapid and sensitive diagnosis.

Evaluation of recombinant outer membrane protein based vaccine against Salmonella Typhimurium in birds.

Food-borne diseases caused by Salmonella enterica from poultry sources represent an important public health problem and no reliable control by vaccination has proved effective despite research. The aim of the present study was to evaluate the use of recombinant OmpC protein for immunization of birds to elucidate its protection against virulent Salmonella Typhimurium. The recombinant OmpC protein was prepared after cloning and expressing ompC gene and was characterized by SDS-PAGE and Western blot analyses. The protein preparations were tested as vaccine candidate in layer birds by comparing the immune response, protection and organ clearance against crude lysate and control. The biologically functional recombinant 43 kDa truncated OmpC protein proved to be a good immunogen which induced a significantly high humoral immune response than control. At the same time, it primed a stable cell-mediated immune response. A protective index (based on faecal shedding of organism) of rOmpC based preparations ranged between 50 and 75% as observed for 3 weeks after challenge. Therefore, the protein preparations conferred satisfactory protection against challenge infections with virulent strains of S. Typhimurium as evidenced by limited faecal shedding and minimal detection of Salmonella from edible tissues and eggs. These findings suggest the possibility to explore the use of S. enterica OMP protein for the production of novel vaccine.

Comparative evaluation of displacement and stress distribution pattern during mandibular arch distalization with extra and inter-radicular mini-implants: a three-dimensional finite element study.

OBJECTIVE: To compare the initial stress distribution and displacement on mandibular dentition using extra and inter-radicular mini-implants for arch distalization, by means of finite element analysis. METHODS: For this study, two finite element models of the mandible were designed. The models consisted of periodontal ligament (PDL) and alveolar bone of all teeth until second molars. In the Case 1, bilateral extra-radicular buccal-shelf stainless steel mini-implants (10.0-mm length; 2.0-mm diameter) were placed between first and second permanent molars. In the Case 2, bilateral inter-radicular stainless steel mini-implants (10.0-mm length; 1.5-mm diameter) were placed between second premolar and first permanent molar. Power hook was attached between canine and first premolar at a fixed height of 8mm. In the two cases, 200g of distalization force was applied. ANSYS v. 12.1 software was used to analyze and compare von Mises stress and displacement in the mandibular dentition, PDL and bone. RESULTS: Higher stresses were observed in mandibular dentition with the inter-radicular implant system. The amount of von Mises stress was higher for cortical bone (85.66MPa) and cancellous bone (3.64MPa) in Case 2, in comparison to cortical bone (41.93MPa) and cancellous bone (3.43MPa) in Case 1. The amount of arch distalization was higher for mandible in Case 1 (0.028mm), in comparison to Case 2 (0.026mm). CONCLUSION: Both systems were clinically safe, but extra-radicular implants showed more effective and controlled distalization pattern, in comparison to inter-radicular implants, in Class III malocclusion treatment.

Antibiotic resistance pattern among the Salmonella isolated from human, animal and meat in India.

The present study was conducted to study the antibiotic resistance pattern among nontyphoidal Salmonella isolated from human, animal and meat. A total of 37 Salmonella strains isolated from clinical cases (human and animal) and meat during 2008-2009 belonging to 12 serovars were screened for their antimicrobial resistance pattern using 25 antimicrobial agents falling under 12 different antibiotic classes. All the Salmonella isolates tested showed multiple drug resistance varying from 5.40% to 100% with 16 of the 25 antibiotics tested. None of the isolates were sensitive to erythromycin and metronidazole. Resistance was also observed against clindamycin (94.59%), ampicillin (86.49%), co-trimoxazole (48.65%), colistin (45.94%), nalidixic acid (35.10%), amoxyclave (18.90%), cephalexin, meropenem, tobramycin, nitrofurantoin, tetracycline, amoxicillin (8.10% each), sparfloxacin and streptomycin (5.40% each). Isolates from clinical cases of animals were resistant to as many as 16 antibiotics, whereas isolates from human clinical cases and meat were resistant to 9 and 14 antibiotics, respectively. Overall, 19 resistotypes were recorded. Analysis of multiple antibiotic resistance index (MARI) indicated that clinical isolates from animals had higher MARI (0.25) as compared to isolates from food (0.22) and human (0.21). Among the different serotypes studied for antibiogram, Paratyhi B isolates, showed resistance to three to 13 antibiotics, whereas Typhimurium strains were resistant to four to seven antibiotics. Widespread multidrug resistance among the isolates from human, animal and meat was observed. Some of the uncommon serotypes exhibited higher resistance rate. Considerable changes in the resistance pattern were also noted. An interesting finding was the reemergence of sensitivity to some of the old antibiotics (chloromphenicol, tetracycline).

Detection of novel sequence types and zoonotic transmission potentiality among strains of Shiga toxigenic Escherichia coli (STEC) from dairy calves, animal handlers and associated environments.

Shiga toxigenic Escherichia coli (STEC) is one of the most important food-borne zoonotic bacterial pathogens responsible for causing gastrointestinal infections, haemorrhagic colitis and haemolytic uremic syndrome. The present study was aimed to isolate and characterize STEC from neonatal dairy calves, animal handlers and their surrounding environment and to establish the genetic relationship among isolates by multilocus sequence typing (MLST). A total number of 115 samples were collected and processed for the isolation of E. coli. The occurrence rate of E. coli was 92.2% (106/115), of which, 18 were typed as STEC. Antibacterial susceptibility analysis revealed 11 (61.1%) strains as multiple drug-resistant (MDR). MLST analysis has delineated 16 sequence types (STs) including nine novel STs. Among STs, ST58 dominated with three strains and was recovered from the environment and neonatal calves. Strains from neonatal calves and humans showed genetic relatedness with significant bootstrap support values indicative of zoonotic transmission potentiality. Analysis of 211 global isolates belonging to 61 STs indicated predominant STs (ST 21, ST 33 and ST 3416) that can be either host-specific (ST 33 and ST 3416) or can be shared among human and bovine hosts (ST 21). The MLST analysis indicates genetic relatedness among isolates and the results predispose inter-host transmission and zoonotic spread.

Proposed low-density lipoprotein cholesterol goals for secondary prevention and familial hypercholesterolemia in India with focus on PCSK9 inhibitor monoclonal antibodies: Expert consensus statement from Lipid Association of India.

BACKGROUND: Rates of atherosclerotic cardiovascular disease (ASCVD) are strikingly high in India compared to Western countries and are increasing. Moreover, ASCVD events occur at a younger age with only modest hypercholesterolemia, most commonly with low levels of high-density lipoprotein cholesterol. The course of ASCVD also appears to be more fulminant with higher mortality. OBJECTIVE: In light of these issues, the Lipid Association of India (LAI) endeavored to develop revised guidelines with more aggressive low-density lipoprotein cholesterol (LDL-C) goals in secondary prevention and for patients with familial hypercholesterolemia compared to guidelines in the United States and other countries. METHODS: Owing to the paucity of clinical outcomes data in India, it was necessary to place major emphasis on expert opinion as a complement to randomized placebo-controlled data generated mostly in non-Indian cohorts. To facilitate this process, the LAI conducted a series of 19 meetings among 162 lipid specialists in 13 cities throughout India over a period of 11 months before formulating this expert consensus statement. RESULTS: The LAI recommends an LDL-C goal <50 mg/dL in all patients in secondary prevention or very high-risk primary prevention but proposes an optional goal ≤30 mg/dL in category A extreme-risk patients (eg, coronary artery disease + familial hypercholesterolemia) and a recommended goal ≤30 mg/dL in category B extreme-risk patients [coronary artery disease + (1) diabetes and polyvascular disease/≥3 major ASCVD risk factors/end organ damage, or (2) recurrent acute coronary syndrome within 12 months despite LDL-C <50 mg/dL, or (3) homozygous familial hypercholesterolemia]. CONCLUSIONS: More aggressive LDL-C goals are needed for prevention of ASCVD in India, as described in this expert consensus statement. Use of statins and ezetimibe needs to increase in India in combination with improved control of other ASCVD risk factors. Proprotein convertase subtilisin kexin type 9 inhibitors can improve LDL-C goal achievement in patients with refractory hypercholesterolemia.

Left atrial isomerism associated with aneurysmal enlargement of right atrial appendage: A case report with literature review.

We present a prenatally diagnosed case of heterotaxy syndrome (HS) in which left atrial isomerism (LAI) was associated with an aneurysmal enlargement of the right atrial appendage (RAA). Although LAI is usually associated with complex cardiac and extracardiac anomalies, the association of LAI and right atrial appendage aneurysm (RAAA) is exceptional. Congenital RAAA itself is an idiopathic, very rare cardiac anomaly characterized by the enlargement of the appendage in the absence of any other cardiac or extra-cardiac defect. The prognosis of the heterotaxy is poor with associated major cardiac malformations and even cases with minor cardiac anomalies are at risk postnatally for complications like biliary atresia, intestinal rotational abnormalities, and immune disorders. In this case, the prenatal diagnosis of the isomerism was mainly based on the abnormalities of caval veins. Although no typical complex cardiac anomaly was present, the HS was associated with biliary atresia, polysplenia, and malrotation of the gut. Associated RAAA further imposed an additional risk of complications such as tachyarrhythmias, thromboembolic events, and aneurysmal rupture.

Survivability of highly pathogenic avian influenza virus (H5N1) in naturally preened duck feathers at different temperatures.

Ducks are the "Trojan Horses" for Asian H5N1 avian influenza viruses (AIV) and attain carrier status without displaying overt infection. These birds help in the spread of the virus among the poultry and human population through direct or indirect contact. Preen oil is the secretion of preen gland of water birds such as ducks. In a process called preening, the water birds spread preen oil across their feather and body. Preen oil has been known to play a significant role in the accumulation of various pathogens including Highly Pathogenic Avian Influenza (HPAI) from water onto feathers. However, the studies are scarce on the role of preen oil in the survivability of HPAIV. We conducted a simulative study to analyse the effect of preen oil on the survivability of the HPAI virus (H5N1) on duck feathers. Duck feather samples along with relevant controls were spiked with the H5N1 virus at two different initial concentrations (104 EID50 and 106 EID50 ), stored at 37°C, 25°C and 10°C temperatures and tested at regular intervals for percent infectivity by egg culture method and qRT-PCR. The infectivity and viral load were significantly higher in naturally preened duck feathers in comparison to the three preen oil deficit controls at both low and high initial concentrations of virus (104 EID50 and 106 EID50 ). Maximum persistence was seen at 10°C in naturally preened duck feathers spiked with 106 EID50 concentration of viruses. It was also seen that depletion of preen oil from duck feathers reduced the persistence of the virus. These results demonstrate that preen oil plays a significant role in survivability and protection of HPAIV on duck feathers. This study herein will present new avenues in understanding one of the epidemiological niches of HPAIV.

Captive wildlife from India as carriers of Shiga toxin-producing, Enteropathogenic and Enterotoxigenic Escherichia coli.

Shiga toxin-producing Escherichia coli (STEC), Enteropathogenic E. coli (EPEC), and Enterotoxigenic E. coli (ETEC) make up an important group of pathogens causing major animal and public health concerns worldwide. The aim of this study was to determine the prevalence of different pathotypes of E. coli in captive wildlife. We analyzed 314 fresh fecal samples from captive wildlife, 30 stool swabs from animal caretakers, and 26 feed and water samples collected from various zoological gardens and enclosures in India for the isolation of E. coli, followed by pathotyping by multiplex PCR. The overall occurrence rate of E. coli was 74.05% (274/370). The 274 E. coli isolates were pathotyped by multiplex PCR targeting 6 genes. Of them, 5.83% were pathotyped as EPEC, 4.74% as STEC, and 1.09% as ETEC. The 16S rRNA genes from the selected isolates were amplified, sequenced, and a phylogenetic tree was constructed. The phylogenetic tree exhibited indiscriminate genetic profiling and some isolates from captive wild animals had 100% genetic identity with isolates from caretakers, suggesting that captive wildlife may serve as a reservoir for infection in humans and vice-versa. The present study demonstrates for the first time the prevalence of these E. coli pathotypes in captive wildlife in India. Our study suggests that atypical EPEC strains are more frequent than typical EPEC strains in captive wildlife. Discovering the implications of the prevalence of these pathotypes in wildlife conservation is a challenging topic to be addressed by further investigations.

Comparative evaluation of displacement and stress distribution pattern during mandibular arch distalization with extra and inter-radicular mini-implants: a three-dimensional finite element study

ABSTRACT Objective: To compare the initial stress distribution and displacement on mandibular dentition using extra and inter-radicular mini-implants for arch distalization, by means of finite element analysis. Methods: For this study, two finite element models of the mandible were designed. The models consisted of periodontal ligament (PDL) and alveolar bone of all teeth until second molars. In the Case 1, bilateral extra-radicular buccal-shelf stainless steel mini-implants (10.0-mm length; 2.0-mm diameter) were placed between first and second permanent molars. In the Case 2, bilateral inter-radicular stainless steel mini-implants (10.0-mm length; 1.5-mm diameter) were placed between second premolar and first permanent molar. Power hook was attached between canine and first premolar at a fixed height of 8mm. In the two cases, 200g of distalization force was applied. ANSYS v. 12.1 software was used to analyze and compare von Mises stress and displacement in the mandibular dentition, PDL and bone. Results: Higher stresses were observed in mandibular dentition with the inter-radicular implant system. The amount of von Mises stress was higher for cortical bone (85.66MPa) and cancellous bone (3.64MPa) in Case 2, in comparison to cortical bone (41.93MPa) and cancellous bone (3.43MPa) in Case 1. The amount of arch distalization was higher for mandible in Case 1 (0.028mm), in comparison to Case 2 (0.026mm). Conclusion: Both systems were clinically safe, but extra-radicular implants showed more effective and controlled distalization pattern, in comparison to inter-radicular implants, in Class III malocclusion treatment.

RESUMO Objetivo: Comparar a distribuição da tensão inicial e o deslocamento na dentição inferior usando mini-implantes extra e inter-radiculares para distalização da arcada, por meio da análise de elementos finitos. Métodos: Dois modelos de elementos finitos da mandíbula foram criados, os quais consistiram de ligamento periodontal (PDL) e osso alveolar de todos os dentes até os segundos molares. No Caso 1, mini-implantes extra-radiculares de aço inoxidável (10,0 mm de comprimento; 2,0 mm de diâmetro) foram colocados bilateralmente na buccal-shelf entre o primeiro e o segundo molares permanentes. No Caso 2, mini-implantes de aço inoxidável inter-radiculares (comprimento de 10,0 mm; diâmetro de 1,5 mm) foram colocados bilateralmente entre o segundo pré-molar e o primeiro molar permanentes. Um Power hook foi preso entre o canino e o primeiro pré-molar a uma altura fixa de 8mm. Nos dois casos, foi aplicada força de distalização de 200g. O software ANSYS v. 12.1 foi usado para analisar e comparar a tensão de von Mises e o deslocamento na dentição inferior, ligamento periodontal e osso. Resultados: Maiores tensões foram observadas na dentição inferior com o sistema de implantes inter-radiculares. A quantidade de tensões de von Mises foi maior para osso cortical (85,66MPa) e osso esponjoso (3,64MPa) no Caso 2, em comparação com osso cortical (41,93MPa) e osso esponjoso (3,43MPa) no Caso 1. A quantidade de distalização da arcada inferior foi maior no Caso 1 (0,028 mm), em comparação com o Caso 2 (0,026 mm). Conclusão: Ambos os sistemas foram clinicamente seguros, mas os implantes extra-radiculares mostraram um padrão de distalização mais eficaz e controlado, em comparação com os implantes inter-radiculares, para tratamento da má oclusão de Classe III.