fulltext.study @t Gmail

Bioresorbable devices made of forged composites of hydroxyapatite (HA) particles and poly l-lactide (PLLA). Part II: practical properties of miniscrews and miniplates

Paper ID Volume ID Publish Year Pages File Format Full-Text
13542 876 2001 15 PDF Available
Title
Bioresorbable devices made of forged composites of hydroxyapatite (HA) particles and poly l-lactide (PLLA). Part II: practical properties of miniscrews and miniplates
Abstract

Miniscrews and miniplates made of forged composites composed of raw hydroxyapatite (u-HA) particles (particle size 0.2–20 μm, averaging 3.0 μm, Ca/p=1.69 and containing CO32−) and a poly l-lactide (PLLA, about 180 kDa, containing residual 0.05 wt% lactide) with osteological bioactivity such as direct bonding to bone and osteoconductivity, total resorbability and radiopacity were examined for various mechanical properties in order to evaluate their usefulness for cranio-, oral and maxillo-facial as well as plastic and reconstructive surgeries with PLLA-only or titanium devices. The composites containing u-HA particles at 30 wt% for miniscrews and 40 wt% for miniplates were selected based on total mechanical strengths and bioactivity, respectively. It was found that the composite devices generally had slightly different mechanical properties than forged PLLA-only devices of which strengths are ranked the highest among the reinforced PLLA-only ones that having been used in many clinical cases to date, in spite of their approximate 2 or 3 times lower absolute strengths than those of titanium ones. However, a remarkable distinction that makes the composite miniplates stand above the titanium ones was confirmed on their fatigue resistance to alternate bendings such that they retained 70% of their initial strength even after 60 times without revealing any damage, whereas the metallic devices fully broke off at only 8 times. This behavior was similar to that of forged PLLA-only devices but is unique as composites made of organic polymers divided by inorganic particles. In addition, profile plates such as L-, T-, X, T, C-, Mesh-, Box-, and Barhole types which were processed by forging twice exhibited nearly directional isotropy in strength and could be deformed in situ at ordinary temperatures to adjust their shapes along the surface undulations of the skull, mandible, maxilla, zygomatic bone and the like without thermoforming and did not return to their original shapes inside an alive body due to the high PLLA’s Tg (65°C) over an alive body temperature (37°C). Since it had already been confirmed in previous papers that these stiff and tough composites have the osteological bioactivity which is missing from both PLLA-only and titanium ones, and radiopacity which is wanting in PLLA-only ones, these various small and thin screws and plates have conclusively less objectionable practicality for use in oral-maxillo and craniofacial as well as plastic and reconstructive surgeries.

Keywords
Miniplates and miniscrews; Cranio, oral and maxillofacial; Hydroxyapatite; Poly l-lactide; Bioactive; Bioresorbable
First Page Preview
Bioresorbable devices made of forged composites of hydroxyapatite (HA) particles and poly l-lactide (PLLA). Part II: practical properties of miniscrews and miniplates
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us
Publisher
Database: Elsevier - ScienceDirect
Journal: Biomaterials - Volume 22, Issue 23, December 2001, Pages 3197–3211
Authors
, ,
Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us