Barrier membranes are commonly used as part of the dental surgical technique guided bone regeneration(GBR)and are often made of resorbable collagen or non-resorbable materials such as PTFE.While collagen membranes do ...Barrier membranes are commonly used as part of the dental surgical technique guided bone regeneration(GBR)and are often made of resorbable collagen or non-resorbable materials such as PTFE.While collagen membranes do not provide sufficient mechanical protection of the covered bone defect,titanium reinforced membranes and non-resorbable membranes need to be removed in a second surgery.Thus,biodegradable GBR membranes made of pure magnesium might be an alternative.In this study a biodegradable pure magnesium(99.95%)membrane has been proven to have all of the necessary requirements for an optimal regenerative outcome from both a mechanical and biological perspective.After implantation,the magnesium membrane separates the regenerating bone from the overlying,faster proliferating soft tissue.During the initial healing period,the membrane maintained a barrier function and space provision,whilst retaining the positioning of the bone graft material within the defect space.As the magnesium metal corroded,it formed a salty corrosion layer and local gas cavities,both of which extended the functional lifespan of the membrane barrier capabilities.During the resorption of the magnesium metal and magnesium salts,it was observed that the membrane became surrounded and then replaced by new bone.After the membrane had completely resorbed,only healthy tissue remained.The in vivo performance study demonstrated that the magnesium membrane has a comparable healing response and tissue regeneration to that of a resorbable collagen membrane.Overall,the magnesium membrane demonstrated all of the ideal qualities for a barrier membrane used in GBR treatment.展开更多
An ideal fixation system for guided bone(GBR)regeneration in oral surgery must fulfil several criteria that includes the provision of adequate mechanical fixation,complete resorption when no longer needed,complete rep...An ideal fixation system for guided bone(GBR)regeneration in oral surgery must fulfil several criteria that includes the provision of adequate mechanical fixation,complete resorption when no longer needed,complete replacement by bone,as well as be biocompatible and have a good clinical manageability.For the first time,a biodegradable magnesium fixation screw made of the magnesium alloy WZM211 with a MgF2 coating has been designed and tested to fulfill these criteria.Adequate mechanical fixation was shown for the magnesium fixation screw in several benchtop tests that directly compared the magnesium fixation screw with an equivalent polymeric resorbable device.Results demonstrated slightly superior mechanical properties of the magnesium device in comparison to the polymeric device even after 4 weeks of degradation.Biocompatibility of the magnesium fixation screw was demonstrated in several in vitro and in vivo tests.Degradation of the magnesium screw was investigated in in vitro and in vivo tests,where it was found that the screw is resorbed slowly and completely after 52 weeks,providing adequate fixation in the early critical healing phase.Overall,the magnesium fixation screw demonstrates all of the key properties required for an ideal fixation screw of membranes used in guided bone regeneration(GBR)surgeries.展开更多
The successful application of magnesium(Mg)alloys as biodegradable bone substitutes for critical-sized defects may be comprised by their high degradation rate resulting in a loss of mechanical integrity.This study inv...The successful application of magnesium(Mg)alloys as biodegradable bone substitutes for critical-sized defects may be comprised by their high degradation rate resulting in a loss of mechanical integrity.This study investigates the degradation pattern of an open-porous fluoride-coated Mg-based scaffold immersed in circulating Hanks’Balanced Salt Solution(HBSS)with and without in situ cyclic compression(30 N/1 Hz).The changes in morphological and mechanical properties have been studied by combining in situ high-resolution X-ray computed tomography mechanics and digital volume correlation.Although in situ cyclic compression induced acceleration of the corrosion rate,probably due to local disruption of the coating layer where fatigue microcracks were formed,no critical failures in the overall scaffold were observed,indicating that the mechanical integrity of the Mg scaffolds was preserved.Structural changes,due to the accumulation of corrosion debris between the scaffold fibres,resulted in a significant increase(p<0.05)in the material volume fraction from 0.52±0.07 to 0.47±0.03 after 14 days of corrosion.However,despite an increase in fibre material loss,the accumulated corrosion products appear to have led to an increase in Young’s modulus after 14 days as well as lower third principal strain(εp3)accumulation(-91000±6361μεand-60093±2414μεafter 2 and 14 days,respectively).Therefore,this innovative Mg scaffold design and composition provide a bone replacement,capable of sustaining mechanical loads in situ during the postoperative phase allowing new bone formation to be initially supported as the scaffold resorbs.展开更多
文摘Barrier membranes are commonly used as part of the dental surgical technique guided bone regeneration(GBR)and are often made of resorbable collagen or non-resorbable materials such as PTFE.While collagen membranes do not provide sufficient mechanical protection of the covered bone defect,titanium reinforced membranes and non-resorbable membranes need to be removed in a second surgery.Thus,biodegradable GBR membranes made of pure magnesium might be an alternative.In this study a biodegradable pure magnesium(99.95%)membrane has been proven to have all of the necessary requirements for an optimal regenerative outcome from both a mechanical and biological perspective.After implantation,the magnesium membrane separates the regenerating bone from the overlying,faster proliferating soft tissue.During the initial healing period,the membrane maintained a barrier function and space provision,whilst retaining the positioning of the bone graft material within the defect space.As the magnesium metal corroded,it formed a salty corrosion layer and local gas cavities,both of which extended the functional lifespan of the membrane barrier capabilities.During the resorption of the magnesium metal and magnesium salts,it was observed that the membrane became surrounded and then replaced by new bone.After the membrane had completely resorbed,only healthy tissue remained.The in vivo performance study demonstrated that the magnesium membrane has a comparable healing response and tissue regeneration to that of a resorbable collagen membrane.Overall,the magnesium membrane demonstrated all of the ideal qualities for a barrier membrane used in GBR treatment.
文摘An ideal fixation system for guided bone(GBR)regeneration in oral surgery must fulfil several criteria that includes the provision of adequate mechanical fixation,complete resorption when no longer needed,complete replacement by bone,as well as be biocompatible and have a good clinical manageability.For the first time,a biodegradable magnesium fixation screw made of the magnesium alloy WZM211 with a MgF2 coating has been designed and tested to fulfill these criteria.Adequate mechanical fixation was shown for the magnesium fixation screw in several benchtop tests that directly compared the magnesium fixation screw with an equivalent polymeric resorbable device.Results demonstrated slightly superior mechanical properties of the magnesium device in comparison to the polymeric device even after 4 weeks of degradation.Biocompatibility of the magnesium fixation screw was demonstrated in several in vitro and in vivo tests.Degradation of the magnesium screw was investigated in in vitro and in vivo tests,where it was found that the screw is resorbed slowly and completely after 52 weeks,providing adequate fixation in the early critical healing phase.Overall,the magnesium fixation screw demonstrates all of the key properties required for an ideal fixation screw of membranes used in guided bone regeneration(GBR)surgeries.
文摘The successful application of magnesium(Mg)alloys as biodegradable bone substitutes for critical-sized defects may be comprised by their high degradation rate resulting in a loss of mechanical integrity.This study investigates the degradation pattern of an open-porous fluoride-coated Mg-based scaffold immersed in circulating Hanks’Balanced Salt Solution(HBSS)with and without in situ cyclic compression(30 N/1 Hz).The changes in morphological and mechanical properties have been studied by combining in situ high-resolution X-ray computed tomography mechanics and digital volume correlation.Although in situ cyclic compression induced acceleration of the corrosion rate,probably due to local disruption of the coating layer where fatigue microcracks were formed,no critical failures in the overall scaffold were observed,indicating that the mechanical integrity of the Mg scaffolds was preserved.Structural changes,due to the accumulation of corrosion debris between the scaffold fibres,resulted in a significant increase(p<0.05)in the material volume fraction from 0.52±0.07 to 0.47±0.03 after 14 days of corrosion.However,despite an increase in fibre material loss,the accumulated corrosion products appear to have led to an increase in Young’s modulus after 14 days as well as lower third principal strain(εp3)accumulation(-91000±6361μεand-60093±2414μεafter 2 and 14 days,respectively).Therefore,this innovative Mg scaffold design and composition provide a bone replacement,capable of sustaining mechanical loads in situ during the postoperative phase allowing new bone formation to be initially supported as the scaffold resorbs.
