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Author: Igor Linetskiy
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Languages : en
Pages :
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Short implants are indispensable in posterior maxilla with insufficient bone height. Implant design, bone quality and degree of bone loss predetermine safe functional load transfer to adjacent bone. Adequate bone strains are key stimuli of bone turnover, but their extreme magnitudes lead to implant failure. Computer simulation allows to correlate bone and implant parameters with bone strain spectrum and to evaluate implant perspective.The aim of the study was to evaluate the impact of plateau implants and bone quality on strain levels in adjacent bone at several levels of bone loss to assess implant prognosis.Cortical and cancellous bone first principal strains (FPSs) were selected to evaluate bone turnover around fully and partially osseointegrated 4.5 (N), 5.0 (M) and 6.0 mm (W) diameter and 5.0 mm length Bicon SHORTu00ae implants at five levels of bone loss from 0.2 to 1.0 mm. Implant 3D models were placed crestally in corresponding posterior maxilla segment models with type III bone and 1.0 mm cortical crestal and sinus bone layers. The models were designed in Solidworks 2016 software. All materials were assumed as linearly elastic and isotropic. Elasticity modulus of cortical bone was 13.7 GPa, cancellous bone u2013 1.37 GPa. Bone-implant assemblies were analyzed in FE software Solidworks Simulation. A total number of 4-node 3D FEs was up to 3,450,000. 120.92 N mean maximal oblique load (molar area) was applied to the center of 7 Series Low 0u00b0 abutment. Maximal FPSs were correlated with 3000 microstrain minimum effective strain pathological (MESp) to evaluate bone turnover around the implants.Maximal FPSs for osseointegrated implants (1800u20263270 microstrain) were found in the cancellous bone at the first fin edge. For implants with bone loss, they were observed at the same location and were significantly dependent on bone loss level (2140u20263600, 2300u20264100, 2800u20264900, 3500u20265900 and 4200u20267000 microstrain for 0.2, 0.4, 0.6, 0.8 and 1.0 mm bone loss). Maximal FPSs were also substantially dependent on implant diameter: diameter increase from 4.5 to 6.0 mm have led to 41, 44, 43, 41, 40% FPS decrease for 0.2, 0.4, 0.6, 0.8 and 1.0 mm bone loss. Comparing to the osseointegrated implants, the following FPS increase on five bone loss levels was determined: for N implants it was 10, 25, 50, 80 and 114%, for M implants u2013 12, 32, 62, 92, 131%, for W implants u2013 19, 28, 56, 94 and 133%.Bone turnover was found to be significantly influenced by implant diameter and bone loss level. 4.5 mm diameter implant is not recommended for type III bone because bone strains exceed 3000 microstrain threshold even for the osseointegrated implant. 6.0 mm diameter implant caused positive bone turnover balance for up to 0.6 mm bone loss, while 5.0 mm u2013 only for up to 0.3 mm bone loss. Clinicians should consider these findings in treatment with short plateau implants.
Author: Igor Linetskiy
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Short implants are indispensable in posterior maxilla with insufficient bone height. Implant design, bone quality and degree of bone loss predetermine safe functional load transfer to adjacent bone. Adequate bone strains are key stimuli of bone turnover, but their extreme magnitudes lead to implant failure. Computer simulation allows to correlate bone and implant parameters with bone strain spectrum and to evaluate implant perspective.The aim of the study was to evaluate the impact of plateau implants and bone quality on strain levels in adjacent bone at several levels of bone loss to assess implant prognosis.Cortical and cancellous bone first principal strains (FPSs) were selected to evaluate bone turnover around fully and partially osseointegrated 4.5 (N), 5.0 (M) and 6.0 mm (W) diameter and 5.0 mm length Bicon SHORTu00ae implants at five levels of bone loss from 0.2 to 1.0 mm. Implant 3D models were placed crestally in corresponding posterior maxilla segment models with type III bone and 1.0 mm cortical crestal and sinus bone layers. The models were designed in Solidworks 2016 software. All materials were assumed as linearly elastic and isotropic. Elasticity modulus of cortical bone was 13.7 GPa, cancellous bone u2013 1.37 GPa. Bone-implant assemblies were analyzed in FE software Solidworks Simulation. A total number of 4-node 3D FEs was up to 3,450,000. 120.92 N mean maximal oblique load (molar area) was applied to the center of 7 Series Low 0u00b0 abutment. Maximal FPSs were correlated with 3000 microstrain minimum effective strain pathological (MESp) to evaluate bone turnover around the implants.Maximal FPSs for osseointegrated implants (1800u20263270 microstrain) were found in the cancellous bone at the first fin edge. For implants with bone loss, they were observed at the same location and were significantly dependent on bone loss level (2140u20263600, 2300u20264100, 2800u20264900, 3500u20265900 and 4200u20267000 microstrain for 0.2, 0.4, 0.6, 0.8 and 1.0 mm bone loss). Maximal FPSs were also substantially dependent on implant diameter: diameter increase from 4.5 to 6.0 mm have led to 41, 44, 43, 41, 40% FPS decrease for 0.2, 0.4, 0.6, 0.8 and 1.0 mm bone loss. Comparing to the osseointegrated implants, the following FPS increase on five bone loss levels was determined: for N implants it was 10, 25, 50, 80 and 114%, for M implants u2013 12, 32, 62, 92, 131%, for W implants u2013 19, 28, 56, 94 and 133%.Bone turnover was found to be significantly influenced by implant diameter and bone loss level. 4.5 mm diameter implant is not recommended for type III bone because bone strains exceed 3000 microstrain threshold even for the osseointegrated implant. 6.0 mm diameter implant caused positive bone turnover balance for up to 0.6 mm bone loss, while 5.0 mm u2013 only for up to 0.3 mm bone loss. Clinicians should consider these findings in treatment with short plateau implants.
Author: Mehdi Amirhosseini
Publisher: Linköping University Electronic Press
ISBN: 9176852385
Category :
Languages : en
Pages : 50
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Aseptic loosening is the main cause of failure of orthopedic prostheses. With no pharmaceuticals to prevent or mitigate periprosthetic bone degradation, a surgery to replace the loose implant with a new one is the only choice to restore patients’ function. Most studies on mechanisms for aseptic loosening investigate wear debris particle-induced osteolysis. However, pathological loading conditions around unstable implants can also trigger osteoclast differentiation and bone loss. In the first study, global gene expression changes induced by mechanical instability of implants, and by titanium particles were compared in a validated rat model for aseptic loosening. Microarray analysis showed that similar signaling pathways and gene expression patterns are involved in particle- and instability-induced periprosthetic osteolysis with an early onset innate immune response as a hallmark of osteolysis induced by mechanical instability. Further, effects of potential therapeutics on restriction of excessive osteoclast differentiation were evaluated. Wnt signaling pathway is known to regulate bone remodeling. In the second study, effects of inactivation of glycogen synthase kinase 3 beta (GSK-3?), a negative regulator of canonical Wnt signaling, on instability-induced periprosthetic osteolysis were examined using our rat model for aseptic loosening. Inhibition of GSK-3? led to a decrease in osteoclast numbers in the periprosthetic bone tissue exposed to mechanical instability while osteoblast perimeter showed an increase. This was accompanied by higher bone volume fraction (BV/TV) in animals treated with the GSK-3? inhibitor. In the third study, potential beneficial effects of two selective inhibitors of cyclindependent kinase 8/19 (CDK8/19) on bone tissue were evaluated. CDK8/19 is a Mediator complex-associated transcriptional regulator involved in several signaling pathways. CDK8/19 inhibitors, mainly under investigation as treatments for tumors, are reported to enhance osteoblast differentiation and bone formation. We show in this study, for the first time, that inhibition of CDK8/19 led to marked suppression of osteoclast differentiation from bone marrow macrophages in vitro through disruption of the RANK signaling. In mouse primary osteoblasts downregulation of osteopontin mRNA, a negative regulator of mineralization, together with increased alkaline phosphatase activity and calcium deposition indicated that osteoblast mineralization was promoted by CDK8/19 inhibition. Moreover, local administration of a CDK8/19 inhibitor promoted cancellous bone regeneration in a rat model for bone healing. These studies contribute to better understanding of mechanisms behind mechanical instability-induced periprosthetic osteolysis and propose potential therapeutics to restrict bone loss with effects on both osteoclasts and osteoblasts.
Author: Georg Watzek
Publisher: Quintessence Publishing (IL)
ISBN:
Category : Medical
Languages : en
Pages : 200
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Book Description
Bone quality is one of the most important factors in the successful osseointegration of dental implants. However, the concepts of bone quality and compromised bone have never been well defined in the field of implant dentistry. To provide a clear definition of these terms, the contributors to this volume have compiled data from almost two decades of experimental and case studies, resulting in a comprehensive review of the current knowledge regarding the placement of implants in compromised bone. The book also presents specific considerations for placing implants in different types of compromised bone, such as aged, underdeveloped, and irradiated bone. A useful work of reference for implant students, practicing implant clinicians, and implant-oriented researchers.
Author: Larisa Linetska
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Bone loss is the most essential cause of dental implant failure. Comparing to the conventional implants, short implants may fail more rapidly because of their reduced length, especially in case of crestal placement. 0.2 mm mean annual bone loss was recommended as a criterion for implant success. Due to bone loss, even under physiological functional loading, bone overload may occur, which, in turn, provokes complementary bone loss. These processes significantly worsen implant long-term prognosis.The aim of this study was to evaluate and compare load-carrying capacities of the spectrum of fully and partially osseointegrated Bicon short implants to establish their prognosis in posterior maxilla under oblique functional loading.The concept of ultimate functional load (UFL) was proposed (Demenko et al., 2011) to compare load-carrying capacities of fully and partially osseointegrated (0.2 mm annual bone loss) 5.0 (S), 6.0 (M) and 8.0 mm (L) length and 5.0 mm diameter Bicon SHORTu00ae implants. Their 3D models were placed crestally and bicortically in corresponding posterior maxilla segment models with type III bone. They were designed in Solidworks 2016 software and had 1.0 mm cortical crestal and sinus bone layers. Implant and bone were assumed as linearly elastic and isotropic. Elasticity moduli of cortical/cancellous bone were 13.7/1.37 GPa. Bone-implant assemblies were analyzed in FE software Solidworks Simulation. 4-node 3D FEs were generated with a total number of up to 2,532,000. 120.92 N oblique load was applied to the center of 7.0 mm abutment. Von Mises stresses (MESs) were evaluated for bone-implant assemblies to determine UFL magnitudes for fully and partially osseointegrated implants and compare them.Maximal MESs for fully osseointegrated implants (26u202631 MPa) were found on the surface of crestal cortical bone. For partially osseointegrated implants they were discovered in migrating critical points inside crestal cortical bone (27u202632 and 41u202646 MPa for 0.2 and 1.0 mm bone loss). For fully osseointegrated implants, UFL magnitudes were 396u2026465 N. For partially osseointegrated implants and 0.2 bone loss, UFL magnitudes were 377u2026447 N, while for 0.4 mm u2013 356u2026417 N, for 0.6 mm u2013 327u2026366 N, for 0.8 mm u2013 314u2026356 N, and for 1.0 mm u2013294u2026336 N. So, after 5 years in function (1.0 mm bone loss), the following reduction of implant load-carrying capacity was determined: 26, 27 and 28% for S, M and L implants. Thus, all UFL magnitudes were much higher than mean maximal functional loading (120.92 N). Furthermore, for all scenarios, UFL magnitudes were above 275 N maximal functional loading for molar area. Finally, the difference between UFL magnitudes for S and M implants was approximately 5%. Short implant prognosis in terms of gradual bone loss is of crucial importance in implant dentistry. Studied Bicon SHORTu00ae implants were found moderately sensitive to bone loss, at least for 5 years in function and 1.0 mm cortical bone thickness. They were also capable to withstand 275 N maximum functional loading for molar area. Their load-carrying capacity was not substantially dependent on implant length, at least within 5u20268 mm, so this extends their application, especially in bone loss.
Author: KArin Gisel Bedoya
Publisher:
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Languages : en
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The use of short implants has gained popularity in the last years, since they have demonstrated high long-term survival and success rates. Also, they allow to reduce treatment time, morbidity and costs compared to bone regeneration procedures. Adequate primary stability and osseointegration are of extreme importance for long-term success of implant therapies.The aim of this study was to assess the relationship between insertion torque (primary stability), premature osseointegration failure and bone loss in patients with short morse taper implants after a 1-year follow-up.6-8mm of vertical bone and 6mm of horizontal bone, evaluated by tomographic examination, were included. A total of 20 morse taper 4 and 5mm in diameter and 5 and 6mm in length dental implants were installed in 11 patients. During implant placement procedures, insertion torques were recorded using a torque wrench and implants were left submerged. After 6 months, second-stage surgeries were performed, signs of premature osseointegration failures evaluated (absence of mobility), provisional crowns delivered and x-rays taken. 1-year after loading, control x-rays were taken. Bone levels were measured in x-rays from the implant platform to marginal bone using ImageJ 1.52d analysis software (National Institutes of Health, Bethesda, USA). Loading and follow-up x-rays were compared to assess the amount of bone loss. Data collected was analyzed using different statistical tests in the SPSS software (IBM Statistics version 21).The mean follow-up time after implant placement was 18.75 u00b1 7 months. Three implants were excluded (15%), two due to mechanical failures and one due to biological failures. Mean values for mesial bone measurements at loading (0.95u00b1 0.74) and at control x-rays (0.88 u00b1 0.83), and for distal bone levels at loading (1.12u00b1 0.92) and at control x-rays (1.08 u00b1 0.91) were used to calculate the amount of bone loss in mesial (0.146) and distal sites (0.326), respectively. Correlation values between insertion torque, mesial (r=-0.240) and distal bone loss (r=0.127) were calculated, as well as for insertion torque and osseointegration (r=0.291).Initial and follow-up values for bone loss showed no statistical differences, thus short implants showed stable bone levels after one year of installation. No relation between insertion torque and bone loss nor insertion torque and osseointegration was found, meaning that initial torque has no direct influence on the amount of bone loss and does not predict osseointegration failures. This study demonstrates the success of short implants in a short-term period.
Author: Harry K. Genant
Publisher: Springer
ISBN:
Category : Medical
Languages : en
Pages : 636
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With contributions by numerous experts
Author: Young-Jun Lim
Publisher:
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Languages : en
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Background : Short implants are considered to be the simpler and more effective alternative to complicated bone graft surgery in clinical situations with reduced alveolar bone height. But, a considerable number of clinicians still hesitate to use short implants questioning about their prognoses mainly due to the reduced contact area between the bone and implant and unfavorable crown to implant ratio compared to longer implants. Aim : The aim of the study is to evaluate the clinical and radiographic outcomes of short implants supporting fixed prostheses in posterior regions. Methods : A retrospective study design was adopted. 69 short implants(intra-bony length u2264 8 mm) supporting fixed prostheses in posterior regions of 56 patients were included. The implant success rate and periimplant marginal bone loss were evaluated. The effects of associated factors on the implant performance were analyzed. Results : A total of 3 implants failed. 2 implants were lost before loading and 1 implant was lost at 7 months after loading. The mean follow up was 30.1 months(SD=11.8 months). Success rate was 95.7% and 94.6% for the implant and patient-based analysis respectively. The average marginal bone loss after 1 year of follow-up was 0.02 u00b1 0.16 mm at mesial and 0.03 u00b1 0.14 mm at distal aspect. No relationship was observed between the studied variables and the marginal bone loss. Conclusions: High survival rates for short implants in posterior regions could be achieved with minimal marginal bone loss in this study. Within the limits of the short term follow up, a short implant (u2264 8 mm ) may be considered as a predictable treatment modality for posterior region with reduced bone height.
Author: Herekar Manisha
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Languages : en
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Statement of problem: The peri-implant bone level has been used as one of the criteria to assess the success of dental implants. Bone resorption was accepted as a physiologic response to second-stage implant uncovering An average of 1.2 mm of bone loss around submerged two-piece implants in the first year following restoration was noted. The concept of platform switching was proposed to reduce crestal bone loss around implants. Purpose: This study was attempted to study the influence of platform switching on the marginal bone level alterations around implantsMaterials and Methods: 60 implant sites were divided into two groups i.e a test group and a control group. The test group comprised of platform switched implants and the control group comprised of platform matched implants Radiologic assessment was done at varying time intervals after uncovering of the implant.Results: A Comparison of mean bone loss between platform matched and platform switched abutment as noted on the mesial side showed a non-significant difference (p value=0.92) while on the distal side statistically significant difference was noted. Comparison of the results between 2 groups at 1,2 4,6 months of post abutment placement on the distal side showed a statistically significant difference. (p value=0.024).Conclusion: It was noted that bone loss is more in platform matched abutments as compared to platform switched abutments. It can thus be concluded that platform switching results in peri-implant bone preservation and also has esthetic benefits.
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Languages : en
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BackgroundImplant-supported rehabilitation of the edentulous posterior jaws can be a challenging situation due to a relevant atrophy of the residual bone. An alternative approach to bone regenerative procedures is the use of short implants (intrabony implant length greater than or equal to 6 mm). It represents a less-invasive treatment with growing evidence of acceptable long-term survival rates.AimTo evaluate the survival and the marginal bone loss of 5 mm and 6 mm short implants supporting conventionally and immediately non functionally loaded fixed rehabilitations. Data are presented at 1 and 2-year follow-up from the prosthetic loading.Materials and Methods36 patients were consecutively included. Inclusion criteria were the absence of one or more maxillary or mandibular molar and premolar associated to alveolar bone atrophy (height between 6 mm and 8 mm, width at least 8 mm). Fifty-six 5mm and 6mm short implants were positioned (of these, 17 implants immediately non functionally loaded in 13 patients). Implants were positioned subcrestally and were treated with 4.1 mm immediate platform switching applied to the cover screw if submerged, healing screw or prosthetic abutment when not submerged or immediately loaded. Implant survival and marginal bone loss (MBL) were measured at 1 and 2-year follow-up from the prosthetic loading. Anatomical crown to implant (C/I) ratio was measured as well. The correlations between MBL and the use of low profile abutments, C/I ratio and single/multiple units restorations were assessed using mixed statistical models.ResultatsThe analysis included 11 males and 25 females (median age 62 years, IQR 54-68). Loading was immediate in 17 implants (30%). Low profile abutment was used in 18 implants (32%). Mean C/I ratio was 2.5 (SD 0.6). Implant-based survival was 96% at 1 year (immediate loading 94%; conventional loading 97%) and 88% at 2 years (immediate loading 94%; conventional loading 85%). 4 of these implant failures occurred in 1 patient between the first and the second year after conventional loading. Mean MBL was 0.17 mm (SD 0.30) at 1 year and 0.22 (SD (0.33) at 2 years. MBL at 1 year was not associated with immediate loading (mean difference 0.06 mm, 95%CI -0.25 to 0.13; p=0.54) vs traditional loading. MBL at 2 year was not associated with immediate loading (mean difference 0.06 mm, 95%CI -0.28 to 0.16; p=0.61) vs traditional loading. Low profile was not associated with MBL at 1 year (p=0.42) or at 2 years (p=0.72). C/I ratio was not associated with MBL at 1 year (p=0.42) or at 2 years (p=0.69).Conclusions and Clinical ImplicationsWithin the limitations of this case series, short implants showed acceptable survival rate and MBL. Comparable results were observed between immediate and conventional loading. Further evaluations with a longer follow up are required.
Author: John N. Fordham
Publisher: Springer Science & Business Media
ISBN: 1447107594
Category : Medical
Languages : en
Pages : 234
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The importance of osteoporosis in the United Kingdom as a cause of death and disability is now well recognised. There are in excess of 200,000 osteoporotic-related fractures in the UK per annum asso ciated with an estimated cost of £942,000,000. Following hip fracture it is known that about 50% of patients are unable to live indepen dently and about 20% of such patients die within the first 6 months. These figures, compelling as they are, reflect poorly on current medical practices which manifestly have failed to identify patients with low bone density at risk of fracture. The hope is that the techni cal advances which have enabled bone mineral density, and other allied indices, to be measured with high precision and accuracy offers the chance of identifying patients at risk of fracture and guiding the clinician to make treatment decisions which may reduce the patients' risk of fracture. In the UK, services for identifying patients at risk of fracture are still in their infancy and are not uniformly available throughout the country. This situation is, however, likely to improve particularly fol lowing the publication of the Royal College of Physicians report "Osteoporosis -clinical guidelines for prevention and treatment" and the recognition in "Our Healthier Nation" that osteoporosis pre vention should be included as a target to achieve a reduction of 20% in accidents by 2010.
