臺灣博碩士論文加值系統

齒顎矯正利用牙齒的移動來達到改變咬合及牙齒排列的目的。矯正的機制、力量大小、方向、牙周支持組織中骨密度和骨重塑的過程都會影響牙齒移動方向和距離。在過去的研究中，已經發現骨密度會影響矯正的速度，並且由傳統的組織切片證明在矯正牙齒移動的方向上的壓力側會造成骨密度吸收，相反方向的張力側會造成骨沉積的現象。由最新的有限元素分析法也可以從電腦中模擬矯正期間骨頭和牙周韌帶的變化。但對於真實人體上的骨生理並沒有實際的臨床人體試驗數據。在牙科用電腦斷層掃描的發明下，減少了斷層掃描影像的輻射劑量，以方便利用影像來做判讀及分析的工作。因此本實驗可以利用降低輻射的牙科用電腦斷層掃描影像實際運用在真實人體身上來探討微觀下骨頭在矯正前後的密度變化。本實驗就是利用牙科用電腦斷層掃描影像來探討牙根周圍骨密度在矯正前後變化的情形與牙齒移動方向的相關性。

本實驗利用牙科用電腦斷層掃描儀器(i-CAT)照射八位中國醫藥大學矯正科患者口內上顎右上犬齒到左上犬齒六顆前牙在矯正前和單純leveling and alignment七個月後牙根周圍骨密度，並用Mimics軟體將測量的六顆前牙每顆牙分成上、中、下三段，每一段又分成頰、顎、近心、遠心面，分別記錄，再比較前後兩次測量結果分析牙根周圍骨密度改變情形，與牙齒移動方向的相關性。

本實驗結果發現在矯正七個月後牙根周圍骨密度會降低。並且有57%的牙齒在牙齒移動的壓力側方向上的骨密度改變量會大於其他面，此結論符合矯正壓力側會造成骨吸收的理論。

In orthodontic theory, the ideal occlusion can be achieved by bone remodeling during orthodontic treatment. In the previous studies, most of them are histological studies on animal or human bone blocks. In the recent years, Finite Element Method (FEM) has adopted to show the details of bone remodeling during orthodontic treatment, however, none of them can exactly prove the real bone biology in the human body. In this study, we used dental cone beam computed tomography (CBCT) to evaluate the bone biology during orthodontic treatment. The most advantage of CBCT is that its radiation dose is much less than that of computed tomography. Therefore, we can get the bone density data in 7 months to analyze the bone density variations during orthodontic treatment. The purposes of this study were (a) to measure the variations of bone density before and after the orthodontic leveling and alignment, and (b) to find the correlation between the bone density and direction of tooth movement. Eight patients were selected from the Department of Orthodontics, China Medical University Hospital, Taiwan in this study. Six upper anterior teeth from canine to canine were chosen, and each tooth was divided into three levels (coronal, middle, apex) and four parts (buccal, palatal, mesial, and distal). The above data were collected before and after the orthodontic treatment by CBCT machine (i-CAT), and were further detected via the Mimics software approach.
The results indicated that (1) the bone density around these teeth decreased during orthodontic treatment, and (2) the reducing amount of the bone density were more obviously on the direction of tooth movement in almost 57% of the observed teeth. The discoveries of this study coincided with “the pressure-tension theory”, which stated the bone resorption mainly occurred at the pressured side.

目錄
中文摘要.........................................................................................................................I
英文摘要.......................................................................................................................II
誌謝..............................................................................................................................III
目錄..............................................................................................................................IV
圖目錄.......................................................................................................................XIII
表目錄...........................................................................................................................X

第一章 前言 1
1.1 研究背景 1
1.2 文獻回顧 2
1.2.1 矯正造成牙齒移動的時間分期 3
1.2.1.1依牙齒移動速率分期 3
1.2.1.2依矯正施力期間分期 3
1.2.2 矯正造成牙齒移動的機制 4
1.2.2.1The pressure-tension theory 5
1.2.2.2 The bone-bending theory 5
1.2.2.3 Bioelectric signals in orthodontic tooth movement 6
1.2.2.4牙齒移動之生化反應機制 6
1.2.3 矯正期間齒槽骨周圍組織的變化 8
1.2.3.1 骨重塑的機制 9
1.2.3.2 牙根重塑 10
1.2.3.3牙周韌帶重塑 10
1.2.4 齒槽骨骨質的分類 11
1.2.5牙齒移動與牙根周圍骨密度及施力大小的關係 12
1.2.5.1 牙根周圍骨密度對牙齒移動的影響 12
1.2.5.2 施力力量大小對牙齒移動的影響 13
1.2.6骨密度的測量方式 14
1.2.6.1雙能量電子吸收儀 14
1.2.6.2 超音波 14
1.2.6.3 電腦斷層掃描 15
1.2.6.4 牙科用電腦斷層掃描(CBCT) 15
1.2.7 CBCT的優缺點與在牙科之應用 16
1.2.7.1 CBCT的優點 16
1.2.7.2 CBCT對金屬影像散射程度比較 17
1.2.7.3 CBCT的精準度探討 17
1.2.7.4 CBCT與CT的輻射劑量比較 17
1.2.7.5 CBCT在牙科的應用 19
1.3研究動機及目的 19

第二章 研究材料與方法 21
2.1研究流程概述 21
2.2材料 22
2.2.1病患的來源和條件 22
2.2.2 病患電腦斷層掃描影像取得之標準化 23
2.3矯正器和矯正線的介紹 23
2.4 CBCT儀器(I-CAT)掃描參數設定 24
2.5 牙根周圍骨密度測量方式 24
2.6 CBCT準確度驗證 36
2.6.1儀器精準度驗證 36
2.6.1.1 標準假體於矯正前與矯正後之驗證 36
2.6.1.2 對照組前後驗證 37
2.6.2 量測軟體驗證 37
2.6.3 組內差異驗證 37
2.6.4 組間差異驗證 37
2.7 統計分析 37

第三章 結果 39
3.1患者矯正前後齒顎排列差異 39
3.2患者矯正前後牙根周圍骨密度的改變率 41
3.3患者矯正前牙根周圍分區骨密度 46
3.4患者矯正後牙根周圍分區骨密度 50
3.5患者矯正前後牙根周圍分區骨密度改變量與矯正後牙齒移動方向間關係53

第四章 討論 56
4.1 CBCT與其他測量骨量工具及方法的探討 56
4.2假體物選擇與量測方式準確度之探討 57
4.2.1標準假體的選擇 57
4.2.2比較沒有做矯正者的生理與矯正者的不同 57
4.3矯正後牙根周圍骨密度會變低之可能性探討 57
4.4牙齒移動方向與周圍骨密度影響相關性之探討 59
4.4.1 pressure and tension theory vs Melsen 提出之理論 59
4.4.2牙根分上、中、下三段與pressure and tension theory之相關性 60
4.4.3牙根分頰、顎、近心、遠心四面與pressure and tension theory之相關性 60
4.4.4矯正後牙根周圍骨密度有增加情形之探討 61
4.4.5不同牙齒與pressure and tension theory之相關性 62
4.5本研究之限制 62
4.5.1樣本數量的限制 62
4.5.2單牙根的限制 63
4.5.3骨重塑過程的限制 63
4.5.4目前尚無追蹤樣本的限制 63

第五章 結論與未來展望 64
5.1結論 64
5.2未來展望 64

參考文獻 65


圖目錄
圖1-1矯正、牙齒與牙周支持組織(齒槽骨的關係) 1
圖1-2牙齒移動與齒槽骨壓力側吸收，張力側沉積 8
圖1-3 LEKHOLM AND ZARB 骨密度的分類 11
圖1-4 MICRO CT下牙根被吸收的情形 13
圖2-1 照射CBCT影像的時間 21
圖2-2 流程圖 22
圖2-3 病人照射CONE BEAM CT時的頭部位置 23
圖2-4 重新定位之設定 25
圖2-5 重新定位完成 25
圖2-6 測量部位定義 26
圖2-7牙根周圍定義 27
圖2-8 紅色為頰側 藍色為顎側 粉紅色為近心側 綠色為遠心側 28
圖2-9 利用軟體RESLICE PROJECT將牙齒重新定位 28
圖2-10找出牙根尖點做一連線並設定參數 29
圖2-11利用THRESHOLDING的功能框住牙根，排除牙周韌帶 29
圖2-12利用CROP MASK框住想要測量的牙根 30
圖2-13利用EDIT MASK中的ERASE擦去不接近牙周韌帶的部分 30
圖2-14利用EDIT MASK中的DRAW填補牙周韌帶空缺，控制只有1PIXEL的體積 31
圖2-15利用CAVITY FILL填滿內層 31
圖2-16利用MORPHOLOGY OPERATIONS中DILATE 3 個 PIXEL 32
圖2-17利用BOOLEAN OPERATIONS得到待量測的牙根周圍骨範圍 32
圖2-18排除非海綿骨HU值範圍以下的組織或是空氣 33
圖2-19找出欲測量的牙根周圍是否有密度小於海綿骨的組織或空氣 33
圖2-20 找出HU範圍在-1024 到148間的密度區塊 34
圖2-21得到可以確定是牙根周圍有海綿骨密度以上的骨頭範圍 34
圖2-22利用CROP MASK功能將牙根周圍分成四份 35
圖2-23將牙根分成頰側、顎側、近心側、遠心側以不同顏色標示 35
圖2-24完成並記錄 36
圖3-1 PATIENT #1矯正前後齒顎排列差異。左：矯正前，右：矯正後 39
圖3-2 PATIENT #2矯正前後齒顎排列差異。左：矯正前，右：矯正後 39
圖3-3 PATIENT #3矯正前後齒顎排列差異。左：矯正前，右：矯正後 39
圖3-4 PATIENT #4矯正前後齒顎排列差異。左：矯正前，右：矯正後 40
圖3-5 PATIENT #5矯正前後齒顎排列差異。左：矯正前，右：矯正後 40
圖3-6 PATIENT #6矯正前後齒顎排列差異。左：矯正前，右：矯正後 40
圖3-7 PATIENT #7矯正前後齒顎排列差異。左：矯正前，右：矯正後 40
圖3-8 PATIENT #8矯正前後齒顎排列差異。左：矯正前，右：矯正後 41
圖3-9 PATIENT #1矯正前後牙根周圍骨密度的改變率 41
圖3-10 PATIENT #2矯正前後牙根周圍骨密度的改變率 42
圖3-11 PATIENT #3矯正前後牙根周圍骨密度的改變率 42
圖3-12 PATIENT #4矯正前後牙根周圍骨密度的改變率 43
圖3-13 PATIENT #5矯正前後牙根周圍骨密度的改變率 43
圖3-14 PATIENT #6矯正前後牙根周圍骨密度的改變率 44
圖3-15 PATIENT #7矯正前後牙根周圍骨密度的改變率 44
圖3-16 PATIENT #8矯正前後牙根周圍骨密度的改變率 45
圖4-1矯正前後剖面圖與矯正前後依骨性不動點之疊影 61
圖4-2牙齒移動量改變不大之矯正前後齒顎排列差異 62

表目錄
表1-1 CBCT與CT輻射劑量之比較 18
表3-1 PATIENT #1矯正前牙根周圍分區骨密度 46
表3-2 PATIENT #2矯正前牙根周圍分區骨密度 46
表3-3 PATIENT #3矯正前牙根周圍分區骨密度 47
表3-4 PATIENT #4矯正前牙根周圍分區骨密度 47
表3-5 PATIENT #5矯正前牙根周圍分區骨密度 48
表3-6 PATIENT #6矯正前牙根周圍分區骨密度 48
表3-7 PATIENT #7矯正前牙根周圍分區骨密度 49
表3-8 PATIENT #8矯正前牙根周圍分區骨密度 49
表3-9 PATIENT #1矯正後牙根周圍分區骨密度 50
表3-10 PATIENT #2矯正後牙根周圍分區骨密度 50
表3-11 PATIENT #3矯正後牙根周圍分區骨密度 51
表3-12 PATIENT #4矯正後牙根周圍分區骨密度 51
表3-13 PATIENT #5矯正後牙根周圍分區骨密度 51
表3-14 PATIENT #6矯正後牙根周圍分區骨密度 52
表3-15 PATIENT #7矯正後牙根周圍分區骨密度 52
表3-16 PATIENT #8矯正後牙根周圍分區骨密度 52
表3-17 PATIENT #1矯正前後牙根周圍分區骨密度改變量與矯正後牙齒移動方向 53
表3-18 PATIENT #2矯正前後牙根周圍分區骨密度改變量與矯正後牙齒移動方向 53
表3-19 PATIENT #3矯正前後牙根周圍分區骨密度改變量與矯正後牙齒移動方向 54
表3-20 PATIENT #4矯正前後牙根周圍分區骨密度改變量與矯正後牙齒移動方向 54
表3-21 PATIENT #5矯正前後牙根周圍分區骨密度改變量與矯正後牙齒移動方向 54
表3-22 PATIENT #6矯正前後牙根周圍分區骨密度改變量與矯正後牙齒移動方向 55
表3-23 PATIENT#7矯正前後牙根周圍分區骨密度改變量與矯正後牙齒移動方向 55
表3-24 PATIENT #8矯正前後牙根周圍分區骨密度改變量與矯正後牙齒移動方向 55
表4-1 牙根分段符合比率 60

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