植體周圍骨頭條件的變化對共振頻率測量值的影響

Abstract

目的：共振頻率分析目前已廣泛使用於評估植體周圍骨頭硬度與植體的穩定度，其中OsstellTM將共振頻率轉換成ISQ值的應用最廣。許多的研究顯示ISQ值與植體暴露高度或周圍骨質密度有高度相關性。然而，植體周圍的皮質骨或海綿骨如何影響ISQ值，或植體周圍不同部位骨質的缺陷是否會影響ISQ測量值卻不得而知。因此，本實驗旨在利用不同組合已知密度的人造骨並在植體周圍不同部位製造骨缺陷來探究其中的影響。 材料與方法：實驗共分六組，每組有五個樣本。每一組均以直徑3mm之鑽針鑽孔，並鎖入Branemark® (Nobel Biocare AB, Göteborg, Sweden ) TiUniteTM MK III 3.75 x 10 mm植體。A組為對照組，於兩側貼有50pcf人造骨的15pcf人造骨塊單純鑽洞並植入植體。B、C組除了在模擬海綿骨人造骨塊兩側貼上50 pcf人造骨外，在植體鑽入處(側)也有50 pcf人造骨貼覆。B、C兩組的差異在B組內由15 pcf人造骨構成海綿骨部分，C組則由40 pcf人造骨構成內部海綿骨部分。D、E、F組中，人造骨的組成與A組同：D組，模擬植體鎖入後鄰近植體平台(platform)旁有一新月型深3mm的缺口。E組，製造一個缺口位於植體植入處靠其中一側長邊的鄰面上，使得植體穿入後於植體中段螺紋處旁有一缺陷。F組，在預鑽孔時鑽深14mm，使植體根尖產生一缺陷。在鎖入植體後將OsstellTM轉接器(transducer)依照廠商指示固定在植體上，每一個樣本轉接器分別以垂直樣本長邊對著相對骨缺陷一側的方向(Av1)、平行樣本長邊的方向(Ap)與Av1相對180度(Av2)等三種方向進行測量，每一個方向均測量其共振頻率值三次。實驗結果使用SPSS 15.0 套裝統計軟體，同一組內針對轉接器不同方向的比較分析使用無母數相關性樣本分析Wilcoxon test，而不同組間不論是轉接器相同方向或不同方向的比較分析是使用無母數獨立樣本分析Mann-Whitney U test。 結果：實驗結果在A組與B組的比較中，有統計上有顯著的結果（p＜0.05）。在B、C組間的比較無統計上顯著的結果，只有B組與C組各自在L型轉接器不同方向測量值的比較時，在轉接器於兩不同方向測量值的比較有統計上顯著結果（p＜0.05）。在D、E、F與對照組間轉接器方向相同時的比較，統計結果上均無明顯差異，只有在D組內Dv1與Dp間有統計上顯著的差異( p＜0.05 )。 結論：由實驗結果推論在植體周圍的海綿骨與皮質骨中，皮質骨對ISQ測量值的影響較大。在轉動L型轉接器時，位於植體平台旁新月形的缺陷，會讓L型轉接器在不同的方向測到不同的結果，但位於植體中段或根尖的缺陷，不會影響L型轉接器測量的值。

Objectives: ISQ readings from Osstell machine (resonance frequency analysis) have been used widely to represent the stiffness of peri-implant supporting bone and implant stability. ISQ has been related to bone height and bone quality. However, it is not clear how the cortical layer or trabecular bone contributes to ISQ and whether a bony defect neighboring to an implant affects ISQ. This study's aim was to answer the above questions. Material and Methods: Sawbones with 15pcf, 40 pcf and 50pcf densities were cut into blocks with different sizes respectively and combined into different assembles to represent the trabecular bone block and cortical layer. Six different groups were tested: Group A, 15pcf trabecular bone block with 50 pcf cortical layer on both sides as controlled group. Group B, 15pcf trabecular bone block with 50 pcf cortical layer on top and both sides. Group C, 40pcf trabecular bone block with 50 pcf cortical layer on top and both sides. Groups D,E,F were all made by 15pcf trabecular bone block with 50 pcf cortical layer on both sides. Group D had a defect created near the implant platform. Group E had a defect created near the midportion of implant. Group F had a defect created near the apical portion of implant. All the sample were invested with hard stone on both end to protect the sample from distortion when fixation with 10 kg force on the drilling machine. An implant (Branemark&reg; TiUniteTM MK III 3.75x10mm , Nobel Biocare AB, G&ouml;teborg, Sweden) was screwed at the center of 40x10 mm surface of each bone block after a 3mm drilling site preparation. Each group had 5 samples. An L-shaped OsstellTM transducer was attached to the implant and each sample was tested 3 times with the transducer in M-D or B-L direction. Within the same group, nonparametric related sample test (Wilcoxon test) was performed. Nonparametric independent sample test (Mann-Whitney U test) was applied when data between two groups to detect significant difference. Results:The results showed that significant differences between group A and B were found, but no significant different between group B and C. The direction of transducer could affect ISQ if samples with a cortical layered on top or defects appearing neighbor to the implant plateform (p< 0.05). Conclusion: The findings suggest that cortical bone and trabecular bone contribute differently to ISQ and defects in supporting bone may affect ISQ. Further experiments are necessary to understand ISQ.