| 摘要: | 本研究乃利用燒結的方法製作多孔性氫氧基磷灰石(HA)燒結體，加入聚左乳酸(PLLA)後製成PLLA/HA的複合材，探討作為生物硬組織可吸收性修補材料之物理性質及組織變化。複合材是以砂糖及食鹽當作Filler/Binder，與HA混合後壓製(39kgf/cm2)成型，再以高溫燒結的方法製作多孔性的氫氣基磷灰石(HA)燒結體，浸入分子量7.5萬的聚左乳酸(PLLA)，從濃度2%到20%，讓聚左乳酸(PLLA)能漸漸地浸入HA燒結體的內外孔洞上，最終製成多孔質PLLA/HA複合材。再以DSC, X-ray, 及MTS檢測，DSC和X-ray可以證明PLLA和HA在處理後沒有轉變其他物質，MTS測出本複合材強度可達12 MPa。體外實驗顯示出時間越久，pH値越低，乳酸也持續釋放。
複合材試樣滅菌後，以Beagle Dog為主進行活體實驗，即把PLLA/HA及pure HA分別植入14隻Beagle Dog下顎骨angle部的2x4x2 mm3缺陷，以及一個不放任何材料的control組，在1, 2, 3, 4, 9, 16, 26週後取出觀察比較。組織反應方面，以control組修復的最快，在9週時就長滿新骨；其次是不加PLLA的HA燒結體，雖然在初期有些微纖維組織干擾，在26週時也長滿一半新骨；最差的則是加上PLLA的HA燒結體，雖然在偏光顯微鏡的觀察下，PLLA隨著時間順利降解，但事實上一直到26週，才長滿骨細胞，而且整個骨組織的空腔常常包了纖維組織。所以本研究發現，PLLA雖然可以增加HA燒結體的強度，在組織方面卻造成不必要的困擾。
The purpose of this study was to investigate tissue responses of porous poly(L-lactide) (PLLA)/ hydroxyapatite (HA) composites as biodegradable materials. The porous HA was obtained by mixing HA with the same amounts of sucrose as binder and salt as filler, pressing the mixure under 39 kgf/cm2 for 5 minutes, melting the sucrose at 220 C and sintering under 1345C for 10 hours then. The obtained porous HA was immersed into graded PLLA solution series[1%, 5%, 10%, 20%] while the used PLLA was prepared via a thermal degradation method. Differential scanning calorimeter, material testing system, X-ray diffractometer were used to measure the physical properties of the composites. In vitro study suggested that PLLA might provide the acid environment to help HA to dissolve.
After sterilization, the composites are implanted into the 2x4x2 mm3 defects on mandible bones of 14 Beagle dogs. Two kinds of implants were used — HA with PLLA and without PLLA. 1, 2, 3, 4, 9, 16, 26 weeks after implantation, the samples were examined histologically by light microscopy. The results showed that new bone formation happened most fast in control groups, then HA-without-PLLA groups, slowest in HA-with-PLLA groups. PLLA/HA may not be good materials for bone grafts but the improved bending strength may be an advantage as implants. |
