Current Issue : July - September Volume : 2018 Issue Number : 3 Articles : 5 Articles
Abstract Background: Angulated implants may result in inaccurate impressions, and the impression technique may affect the accuracy of the definitive cast. This study was designed to compare the dimensional accuracy of casts obtained from three impression techniques for three definitive lower casts with implants at different angulations. Methods: Three Osseolink implants were placed in three reference models with different angles (parallel, 15�° and 30�°). Impressions of each model were made with three techniques (n = 10 per group): indirect, unsplinted direct, and acrylic resin-splinted direct technique. Impressions were poured with type IV dental stone. Inter-implant distances were measured for casts using a coordinate measuring machine, and the deviations from the reference models ( r) were calculated. Data were analyzed using one-way ANOVA followed by post hoc tests to detect significance between groups ( =0.05). Results: This study showed that the deviations in micrometers from the reference model were the least for acrylic resin-splinted direct technique ( r1 = 49.96, r2 = 50.36) versus indirect ( r1 = 93.8, r2 = 90.9) and unsplinted direct techniques (( r1=67.07, r2 = 68.66) in 30�° angulated implant situation (p value < 0.0001 for both r1and r2). In 15�° * angulated implants, both the acrylic resin-splinted direct ( r1 = 44.64, r2 = 45.58) and unsplinted direct techniques ( r1 = 47.39, r2 = 55.28) were more accurate than indirect technique ( r1 = 64.8, r2=68.3)(p value < 0.0001 for * both r1and r2). While in parallel condition, no difference was found between all three techniques (p value = 0.085, 0.056 for r1and r2, respectively). Conclusions: The impression technique affected the accuracy of definitive casts. The acrylic resin splinted direct technique produced the most accurate casts, followed by direct unsplinted and indirect techniques. Furthermore, implant angulation affected the impression accuracy. When implant angulation increased from parallel implants to 30�°, the forces of deformation increased, which resulted in increased distortion. Keywords: Direct technique, Indirect technique, Internal connection implant, Splinting procedure \n\nCast accuracy obtained from different... (PDF Download Available). Available from: https://www.researchgate.net/publication/324606063_Cast_accuracy_obtained_from_different_impression_techniques_at_different_implant_angulations_in_vitro_study [accessed Jun 22 2018]....
A literature review of finite element analysis (FEA) studies of dental implants with their model validation process\nwas performed to establish the criteria for evaluating validation methods with respect to their similarity to biological\nbehavior. An electronic literature search of PubMed was conducted up to January 2017 using the Medical Subject\nHeadings ââ?¬Å?dental implantsââ?¬Â and ââ?¬Å?finite element analysis.ââ?¬Â After accessing the full texts, the context of each article was\nsearched using the words ââ?¬Å?validââ?¬Â and ââ?¬Å?validationââ?¬Â and articles in which these words appeared were read to determine\nwhether they met the inclusion criteria for the review. Of 601 articles published from 1997 to 2016, 48 that met the\neligibility criteria were selected. The articles were categorized according to their validation method as follows: in vivo\nexperiments in humans (n = 1) and other animals (n = 3), model experiments (n = 32), othersââ?¬â?¢ clinical data and past\nliterature (n = 9), and other software (n = 2). Validation techniques with a high level of sufficiency and efficiency are still\nrare in FEA studies of dental implants. High-level validation, especially using in vivo experiments tied to an accurate\nfinite element method, needs to become an established part of FEA studies. The recognition of a validation process\nshould be considered when judging the practicality of an FEA study....
Background: Until now, sinus floor elevation represents the gold standard procedure in the atrophic maxilla in\norder to facilitate dental implant insertion. Although the procedure remains highly predictive, the perforation of the\nSchneiderian membrane might compromise the stability of the augmented bone and implant success due to\nchronic sinus infection. The aim of this retrospective cohort study was to show that a membrane tear, if detected\nand surgically properly addressed, has no influence on the survival of dental implants and bone resorption in the\naugmented area.\nMethods: Thirty-one patients with 39 perforations could be included in this evaluation, and a control group of 32\npatients with 40 sinus lift procedures without complications were compared regarding the radiographically\ndetermined development of bone level, peri-implant infection, and implant loss.\nResults: Implant survival was 98.9% in the perforation group over an observation period of 2.7 (�± 2.03) years\ncompared to 100% in the control group after 1.8 (�± 1.57) years. The residual bone level was significantly lower in\nthe perforation group (p = 0.05) but showed no difference direct postoperatively (p = 0.7851) or in the follow-up\nassessment (p = 0.2338). Bone resorption remained not different between both groups (p = 0.945). A two-stage\nprocedure was more frequent in the perforation group (p = 0.0003) as well as peri-implantitis (p = 0.0004).\nConclusions: Within the limits of our study, the perforation of the Schneiderian membrane did not have a negative\nimpact on long-term graft stability or the overall implant survival....
Background: Dental implants are frequently applied to unilateral defects in the mandible. However, implant\nplacement in the molar region of the mandible can be difficult due to anatomical structure. The aim of this study\nwas to evaluate the distribution of occlusal force in a mandibular shortened dental arch (SDA) with implants.\nMethods: Three-dimensional finite element (FE) models of the mandible with varying numbers of teeth and implants\nwere constructed. Models Im6 and Im67 contained one and two implants in the defect of the left molar region,\nrespectively. Models Im456 and Im4567 contained three and four implants in the defect of the left premolar and molar\nregions, respectively. Model MT67 contained a defect in the molar region with no implant placed. Model MT7\nrepresented natural dentition without a left second molar, as a control. Modification of the condition of\nocclusal contacts assuming the intercuspal position was performed before analysis under load 400 N; therefore, the\nload condition as total force on the occlusal surface was 400 N. FE analyses were subsequently performed under load\nconditions of loads 100, 200, and 800 N. The distribution of reaction forces on the occlusal surface and the mandibular\ncondyle was investigated.\nResults: Force distribution in models Im67 and Im4567 appeared to be symmetrical under all load conditions. Occlusal\nforce distribution in models Im6 and Im456 was similar to that in model MT7. However, the occlusal force at the\nsecond premolars on the defect side in those models was larger under loads 100 and 200 N. Conversely, the occlusal\nforce on the first molars was much larger than that in model MT7 under load 800 N.\nConclusions: Within the limitations of this theoretical study, we demonstrated that restoration with the same number\nof implants as missing teeth will show almost symmetric occlusal force distribution, and it will produce less\nbiomechanically stress for a unilateral defect of the mandible. However, if restoration of a missing second\nmolar with an implant is impossible or difficult, then an SDA with implants may also be acceptable except\nfor individuals with severe bruxism....
Background: Non-nutritive sucking habits may adversely affect the orofacial complex. This systematic literature\nreview aimed to find scientific evidence on the effect of pacifier sucking on orofacial structures.\nMethods: A search on MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and Web of Science\ndatabases was conducted to find all pertinent articles published from inception until February 2018, based on the\nPreferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The quality of the studies\nwas evaluated using the risk of bias judgements in non-randomized studies of interventions (ROBINS-I).\nResults: Among the 2288 articles found, 17 articles met the selection criteria: seven prospective cohort studies, nine\ncross-sectional studies, and one randomized clinical trial. Using ROBINS-I, 12 studies were evaluated to have a\nserious overall risk of bias and five, a moderate one.\nThese studies claimed a strong association between a pacifier sucking habit and the presence of an anterior open\nbite and posterior crossbite. Functional/orthodontic pacifiers were shown to cause significantly less open bites than\nthe conventional ones.\nConclusions: High level of evidence of the effect of sucking habits on orofacial structures is missing. The available\nstudies show severe or moderate risk of bias; hence, the findings in the literature need to be very carefully evaluated.\nThere is moderate evidence that the use of pacifier is associated with anterior open bite and posterior crossbite, thus\naffecting the harmonious development of orofacial structures.\nFunctional/orthodontic pacifiers reduce the prevalence of open bite when compared to the conventional ones, but\nevidence is needed concerning the effects on posterior crossbite. Well-designed randomized controlled trials are\nneeded to further analyze the effects of functional/orthodontic and conventional pacifiers on orofacial structures....
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