使用錐狀射束電腦斷層攝影與根尖X光影像暨碎形維度法分析垂直牙根斷裂及根尖病灶變化

Abstract

牙齒發生垂直牙根斷裂會因為症狀多樣化且沒有明顯影像證據而困擾牙醫師，臨床牙醫師莫不希望透過問世15年的牙科電腦斷層攝影，以及現今影像醫學技術，協助明確且快速診斷。由於牙齒發生垂直牙根斷裂會造成周邊牙周韌帶的破壞，造成齒槽骨吸收，同時牙齒牙根也會產生斷裂，但是透過根尖X光影像來檢視牙齒是否有產生斷裂，也因為斷裂紋太細致，以致於無法在平面X光影像診斷出來；雖然牙科電腦斷層攝影可以提供立體的影像，但是牙醫師對於垂直牙根斷裂的牙齒牙根斷裂裂縫大小毫無概念，對於牙科電腦斷層攝影相對匹配的解析度大小也無從選擇，造成病人接受了不必要的放射檢查與醫療資源浪費。 本實驗主要是收集臨床上因為垂直牙根斷裂的牙齒，透過不同解晰度的錐狀射束電腦斷層攝影，來找出垂直牙根斷裂牙齒最大裂縫尺度，進而讓牙醫師知道如何在不同解晰度中，選擇最適當牙科電腦斷層攝影。在以碎形維度的影像處理方式，來檢視牙齒的根尖X光影像上骨樑，首先透過根管治療結果評估，來確認牙齒周邊齒槽骨的消失與增長模式，是否與臨床根管治療結果一致，進而發現垂直牙根斷裂周邊齒槽骨破壞的模式。 實驗結果發現每顆垂直牙根斷裂牙齒的裂縫大小都不一致，而且型態不盡相同，一半以上大於100μm，雖然有少數案例大於200μm或是只有20μm。而糗小臼齒牙根如果有兩條裂紋或是斷裂紋延伸到牙根尖3mm，牙齒的裂縫相對也是大於100μm。對於碎形維度法在垂直牙根斷裂牙齒的根尖X光影像影像的應用；首先我們收集臨床根管治療成功與失敗案例的根尖X光影像，在根管治療成功的案例，根尖齒槽骨的碎形維度值是增加；相對失敗的案例，根尖齒槽骨的碎形維度值是減少的。同時我們發現牙齒發生垂直牙根斷裂，周邊齒槽骨雖然沒有統計上的顯著變化，但是比較術前術後的根尖X光影像，我們也發現有減少的趨勢。 透過本實驗，可以提供臨床牙醫師判斷是否需要使用牙科電腦斷層攝影診斷垂直牙根斷裂的依據，減少病人不必要的X光放射劑量；；同時透過碎形維度法，也可以提供臨床牙醫師透過根尖X光影像，來診斷牙齒垂直牙根斷裂的新方法。

When the teeth vertical root fracture occurs, it cause damage the surrounding periodontal ligament and alveolar bone resorption quickly. The dentist can not make a correct diagnosis from immediately from these diverse symptoms and no obvious evidence of the image. The purpose of the experiment through medical imaging methods such as fractal dimension in the periapical radiography help dentists diagnose vertical root fracture. Then we used different cone -beam computed tomography with different resolution and find out the width of fracture space of vertical root fracture teeth. Thus dentists realise to choose the proper resolution dental computed tomography to diagnosis vertical root fracture. It was found that the variable width of fracture space between each vertical root fracture teeth. Although some teeth the width of fracture vrthere are over than 200μm or less than 20μm, but more than half of fracture teeth the maximum width larger than 100μm. If the premolar occurred vertical root fracture, the width of fracture space over 100μm company with the fracture line extending to apical 3mm or two fractur line exist in the same root. We also test fractal dimension method in the successful and failure endodontic treatment teeth. The fractal dimension increased in the successful endodontic tx teeth of root apex bone and the failure tx teeth of the border of reaction bone. The fractal dimension decreased in the country in the failure endodontic tx teeth of root apex bone and thesuccessful tx teeth of the border of reaction bone. We have found that fractal dimension values were decreasing trend from four regions of interesting area around the root surrounding alveolar bone although without statistically significant change from two periapical radiiography. The dentists know how to choise dental computed tomography to diagnosis of vertical root fracture teerth through this experiment. We may usd fractal dimension method to help diagnosis vertical root fracture from periapical radiography in the future.