Different Numbers Of Implants Research Articles

Does the prosthesis weight matter? 3D finite element analysis of a fixed implant-supported prosthesis at different weights and implant numbers.

PURPOSEThis study evaluated the influence of prosthesis weight and number of implants on the bone tissue microstrain.MATERIALS AND METHODSFifteen (15) fixed full-arch implant-supported prosthesis designs were created using a modeling software with different numbers of implants (4, 6, or 8) and prosthesis weights (10, 15, 20, 40, or 60 g). Each solid was imported to the computer aided engineering software and tetrahedral elements formed the mesh. The material properties were assigned to each solid with isotropic and homogeneous behavior. The friction coefficient was set as 0.3 between all the metallic interfaces, 0.65 for the cortical bone-implant interface, and 0.77 for the cancellous bone-implant interface. The standard earth gravity was defined along the Z-axis and the bone was fixed. The resulting equivalent strain was assumed as failure criteria.RESULTSThe prosthesis weight was related to the bone strain. The more implants installed, the less the amount of strain generated in the bone. The most critical situation was the use of a 60 g prosthesis supported by 4 implants with the largest calculated magnitude of 39.9 mm/mm, thereby suggesting that there was no group able to induce bone remodeling simply due to the prosthesis weight.CONCLUSIONHeavier prostheses under the effect of gravity force are related to more strain being generated around the implants. Installing more implants to support the prosthesis enables attenuating the effects observed in the bone. The simulated prostheses were not able to generate harmful values of peri-implant bone strain.

Impact of Implant Number on Mandibular Implant-Supported Profile Prostheses: A Systematic Review.

To assess studies on edentulous patients rehabilitated using mandibular implant-supported profile prostheses and analyze the impact of different numbers of implants used on the implant survival rate, peri-implant bone loss, and prosthesis survival rate. This systematic review adhered to the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) statement and was registered on PROSPERO. The PubMed/MEDLINE database was searched for articles published before July 18, 2016. The study attempted to answer the following PICO question: In edentulous patients, do full-arch fixed prostheses supported by three implants have a satisfactory implant survival rate, marginal bone loss, and prosthesis survival rate compared with those supported by different numbers of implants? Evidence levels of each study were evaluated using the Oxford Centre for Evidence-Based Medicine (OCEBM); methodologic quality was evaluated using the Methodological Index for Nonrandomized Studies (MINORS) scale and Cochrane Risk of Bias Tool. Descriptive statistics were performed when applicable. Implant survival curves were constructed using the Kaplan-Meier method, and marginal bone loss was analyzed using the Kruskal-Wallis, Dunn's, and Mann-Whitney tests. This analysis included 21 published studies of 4,712 implants and 1,245 mandibular implant-supported profile prostheses in 1,245 patients. The patients were grouped by the number of implants used: group 1 (three implants) had an implant survival rate of 90%; group 2 (four implants) had a rate of 95%; and group 3 (five implants) had the lowest rate, 74%. Groups 1 and 3 had the lowest first-year bone losses (median: 0.73 and 0.70 mm, respectively), and were significantly different from group 2 (median: 1.31 mm; P < .001). Despite the limitations in the studies with low levels of evidence and the methodology of MeSH term research, it was concluded that the implant survival rate and first-year bone loss of full-arch fixed prostheses supported by three implants were satisfactory. However, the prosthesis survival rate was inferior to that of other groups, which suggests a longer follow-up of these rehabilitations.

Influence of implant number on the movement of mandibular implant overdentures

Statement of problemThe rotational movement of an implant overdenture (IOD) has a negative effect on the perceived masticatory ability of the denture wearer. However, the influence of implant number on the movement of IODs has not been investigated. PurposeThe purpose of this in vitro study was to evaluate the denture movement of mandibular IODs anchored by different numbers of implants. Material and methodsAn edentulous mandibular test model with artificial mucosa and 5 experimental overdentures (N=5) was fabricated. The locator attachment system with blue nylon inserts was chosen for this study. Three implant positions were prepared: anterior midline (1-IOD), bilateral lateral incisor regions (2-IOD), and anterior midline and bilateral canine regions (3-IOD). Vertical loads of 50 N were applied to the mid-anterior region, the left canine region, the left premolar region, and the left first molar region. The vertical and horizontal displacements at the right distal edge and the vertical displacements at the loading point were measured. The displacement values were statistically analyzed using a 1-way analysis of variance and the post hoc Tukey honest significant difference test with the implant number as a factor. In addition, the values of the vertical and horizontal displacements at the distal edge of the overdenture were statistically compared using a paired t test, and the values of the vertical displacement at the distal edge of the overdenture were statistically analyzed by a repeated measures analysis of variance and the post hoc Tukey honest significance difference test with the loading point as a factor (a=.05). ResultsUpon anterior loading, the 2-IOD showed significantly larger vertical displacements at the right distal edge than the 1-IOD or 3-IOD (P<.01). The horizontal displacements at the right distal edge were small compared with the vertical displacements at the same point, although the displacement of the 2-IOD was significantly larger than that of the 1-IOD upon anterior loading (P=.03). The magnitude of the vertical displacement at the loading point of the 2-IOD was significantly larger than that of the 3-IOD upon anterior loading (P<.01). No statistically significant differences were shown under the other conditions for each loading (P>.05). ConclusionsWithin the limitations of this in vitro study, the following conclusions were drawn: During mastication with the anterior teeth, the use of 2 implants for anchoring an IOD increased the rotation of the denture base more than the use of 1 or 3 implants. The horizontal movements of the IODs were small compared with the vertical movements. Denture movement under the occlusal force in the molar region was smaller than that in the anterior region.

Remodeling of the Mandibular Bone Induced by Overdentures Supported by Different Numbers of Implants.

The objective of this study was to investigate the process of mandibular bone remodeling induced by implant-supported overdentures. computed tomography (CT) images were collected from edentulous patients to reconstruct the geometry of the mandibular bone and overdentures supported by implants. Based on the theory of strain energy density (SED), bone remodeling models were established using the user material subroutine (UMAT) in abaqus. The stress distribution in the mandible and bone density change was investigated to determine the effect of implant number on the remodeling of the mandibular bone. The results indicated that the areas where high Mises stress values were observed were mainly situated around the implants. The stress was concentrated in the distal neck region of the distal-most implants. With an increased number of implants, the biting force applied on the dentures was almost all taken up by implants. The stress and bone density in peri-implant bone increased. When the stress reached the threshold of remodeling, the bone density began to decrease. In the posterior mandible area, the stress was well distributed but increased with decreased implant numbers. Changes in bone density were not observed in this area. The computational results were consistent with the clinical data. The results demonstrate that the risk of bone resorption around the distal-most implants increases with increased numbers of implants and that the occlusal force applied to overdentures should be adjusted to be distributed more in the distal areas of the mandible.

Stress on implant-supported fixed prostheses with different numbers of abutments after the application of acrylic resin

Statement of problemClinical procedures and laboratory processing techniques inevitably induce stress in the implant/abutment/prosthesis system and may have negative effects when different numbers of implants are used. PurposeThe purpose of the study was to evaluate the tension on the abutments of implant-supported fixed prostheses and to determine the effect of the application of an esthetic veneer (acrylic resin) and the number of abutments (5 or 4). Material and methodsFour palladium-silver alloy cast bars were fabricated to simulate implant-supported fixed complete prostheses. Strain gauges were fixed on the abutments to measure the tension before and after the application of the esthetic veneer. The values of tension were measured in models with 5 or 4 abutments. Data were analyzed with a repeated measures ANOVA. ResultsNo statistically significant differences were found for the main factors (esthetic veneer, P=.22; number of abutments, P=.14) despite the large effect size. ConclusionsThe results of this study suggest that the tension in the abutments of an implant-supported fixed prosthesis is not affected by the application of acrylic resin veneering or by reducing the number of abutments.

Hardware complications related to the surgical fixation of slipped capital femoral epiphyses.

Slipped upper femoral epiphysis is a disabling condition with an annual incidence of 2-13 per 100,000. In situ surgical fixation is the preferred initial treatment for both stable and unstable slipped capital femoral epiphysis (SCFE) cases. The main aim is to avoid further slippage and complications such as osteonecrosis and chondrolysis. The choice of medical implants in managing this condition has changed along the years from large nail-like devices to cannulated screws. The biomechanical properties of different fixation techniques have been studied. All implants have been associated with complications that can occur intraoperatively as well as in the early and late postoperative periods. This report examines a number of different implants used and identifies complications and ways on how to avoid such complications. It also looks at the complications directly related to medical implants in the management of SCFE. We looked at published literature in peer-reviewed journals describing the use of the different medical implants and the documented complications. We also examined literature that suggests ways on how to avoid and manage these complications. A review of the current literature is presented in this text.

Influence of implant number on the biomechanical behaviour of mandibular implant-retained/supported overdentures: A three-dimensional finite element analysis

ObjectiveThe aim of this study was to evaluate strain distribution in peri-implant bone, stress in the abutments and denture stability of mandibular overdentures anchored by different numbers of implants under different loading conditions, through three-dimensional finite element analysis (3D FEA). MethodsFour 3D finite element models of mandibular overdentures were established, using between one and four Straumann implants with Locator attachments. Three types of load were applied to the overdenture in each model: 100N vertical and inclined loads on the left first molar and a 100N vertical load on the lower incisors. The biomechanical behaviours of peri-implant bone, implants, abutments and overdentures were recorded. ResultsUnder vertical load on the lower incisors, the single-implant overdenture rotated over the implant from side to side, and no obvious increase of strain was found in peri-implant bone. Under the same loading conditions, the two-implant-retained overdenture showed more apparent rotation around the fulcrum line passing through the two implants, and the maximum equivalent stress in the abutments was higher than in the other models. In the three-implant-supported overdenture, no strain concentration was found in cortical bone around the middle implant under three loading conditions. Conclusions and clinical significanceSingle-implant-retained mandibular overdentures do not show damaging strain concentration in the bone around the only implant and may be a cost-effective treatment option for edentulous patients. A third implant can be placed between the original two when patients rehabilitated by two-implant overdentures report constant and obvious denture rotation around the fulcrum line.

Circulating concentrations and pattern of luteinizing hormone and follicle-stimulating hormone in circulation are changed by the circulating concentration of 17 beta-estradiol in the bovine male and female.

The objectives of the present study were 1) to determine whether 17 beta-estradiol (E2) regulation of tonic secretion of LH and FSH is sexually differentiated in the bovine and 2) to evaluate the effects of various physiological concentrations of E2 on the profiles and concentrations of gonadotropins in circulation. This was accomplished by administering different numbers of implants containing E2 to gonadectomized bovine males and females. Mean age at initiation of the study was 18.5 mo. Animals received 1, 2, 4, 8, or 16 implants of E2 or a sham implantation. Mean concentrations of LH in circulation and amplitude of LH pulses were similar between males and females after administration of E2. There was a cubic response for mean concentrations of LH and amplitudes of LH pulses across the dosages of E2 administered; lower concentrations of E2 had little effect, whereas higher concentrations of E2 suppressed both mean LH and amplitude of LH pulses. A linear decline in frequency of LH pulses occurred as concentrations of E2 in circulation increased. A treatment x sex interaction resulted for mean concentrations of FSH in circulation. Low doses of E2 resulted in a greater enhancement of circulating concentrations of FSH in males than in females. Tonic secretion of LH in bovine males and females responded in a similar manner to administration of various physiological concentrations of E2; however, a differential response between sexes was observed for FSH.