【Chris Chang Ortho】569. Infra-Zygomatic Crest Miniscrews

Objectives: Assess the 6mo survival (success) rate for infra-zygomatic crest (IZC) bone screws (BSs) relative to patient age, insertion angle, sinus penetration and terminal insertion torque.
Materials and Methods: 100 consecutive patients (27 males, 73 females; mean age 25.8 years, range 11.0–53.8 years) received IZC BSs bilaterally (n=200). Each BS was routinely loaded with up to 14 oz (397g, 389cN), reactivated monthly, and followed for 6mo. Terminal insertion torque was measured, and radiographs were assessed to determine length of the BS engaged in bone, and depth of penetration into the maxillary sinus.
Results: Compared to non-penetrating IZC BSs, the mean results for the 96 (48%) BSs that did penetrate the sinus were: 3.23mm of sinus penetration, 21.3% decrease in terminal insertion torque, and 31.5% less bone contact at the BS osseous interface. Perforation prevalence increased with age from 35.7% (11-19yr) to 62.5% (＞30yr) (p＜.01). Terminal insertion torque increased from 11-19 to 20-29yr due to increasing bone density with age, but then decreased at ＞30yr because of increased incidence of sinus penetration (p＜.05). Sinus penetration had no significant effect on IZC BS survival. About 5% of the devices did fail when the final insertion torque was significantly (p＜.05) decreased to 7.37N-cm compared to the mean torque of 11.63N-cm for successful BSs.
Conclusions: Both sinus perforation and IZC bone quality increased with age. Sinus penetration did not significantly affect the 6mo survival rate of IZC BSs because the loss of bone quantity at the interface was offset by the age-related increase in bone quality at the IZC site.
KEY WORDS: Sinus perforation; Terminal insertion torque; Infra-zygomatic crest; Bone screws; Skeletal anchorage; Primary stability.

目標：評估 IZC 骨釘在六個月內，相對於病患年齡、植入角度、上頜竇穿透程度、及植體終端扭矩等因素之成功率。
研究材料及方法：本研究連續選取100名雙側皆植入 IZC 骨釘的患者 (27位男性、73位女性，平均年齡 25.8，年齡範圍 11.0-53.8 歲) (骨釘總數：200支)。每支骨釘定期每月活化，最高加載 14oz (397g, 389cN)，並持續追蹤六個月。依照植體終端扭矩的測量結果和X-光成像，判斷骨釘與骨質接合的長度、以及其穿透上頜竇的深度。
結果：與無穿透上頜竇之骨釘相比，穿透上頜竇的 96 支骨釘 (48%) 平均數據為：3.23mm 之穿透長度，植體終端流失 21.3% 之扭矩，且在骨釘及骨質交界處少了 31.5% 之骨質接合力。穿透的發生率隨著年齡增加，由 35.7% (11-19歲) 提高至 62.5% (大於30歲) (p＜.01)。植體終端扭力在 11-19 及 20-29歲區間中，因骨密度隨年齡增長而跟著增加，但在大於30歲的患者中，因穿透率提高致使終端扭矩減弱 (p＜.05)。上頜竇穿透並不影響 IZC 骨釘之成功率，然而研究中約有 5% 的骨釘因終端扭矩大幅降低至 7.37N-cm 而失敗 (p＜.05)，相較之下成功案例之平均扭矩則為 11.63N-cm。
結論：隨著年齡，上頜竇穿透發生率及 IZC 處之骨質量皆會提升。上頜穿透在持續六個月的研究中對 IZC 骨釘之成功率無顯著影響，原因在於 IZC 位置之骨質量隨年紀而提升，抵銷了骨釘與骨質交界處發生的骨質流失。
關鍵字：上頜竇穿透，植體終端扭矩，IZC，骨釘，骨性錨定，骨質初級穩定度。

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