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標題: | 不同去鍵結技術對陶瓷托架黏著斷裂模式的影響 Effects of Different Debonding Techniques on the Adhesive Failure Modes of Ceramic Brackets |
作者: | Hsing-Yu Chen 陳幸妤 |
指導教授: | 林俊彬 |
關鍵字: | 陶瓷托架,去鍵結,預裂, ceramic bracket,debonding,pre-crack, |
出版年 : | 2005 |
學位: | 碩士 |
摘要: | 陶瓷托架(ceramic bracket)為因應美觀需求所發展的美觀托架。陶瓷的性質非常堅硬且脆,這兩種性質和陶瓷托架本身與牙齒表面的高鍵結強度造成了臨床使用的一些困難。包括在去鍵結(debonding)的過程中,有托架斷裂和造成牙釉質受損的問題。因而有許多廠商不斷的做一些研究和開發去改變陶瓷托架的托架座(bracket base)的設計,或者引進一些新的去鍵結方法來配合各種不同設計的新型陶瓷托架的設計。
本研究的目的是要評估口外實驗中臨床上常用的陶瓷托架以雙重聚合(dual-cured)矯正黏著劑黏於牙釉質表面,去鍵結所需要的力量大小以及斷裂模式(failure mode)。實驗使用之托架包括單晶型的矯正托架(Inspire, Ormco, Orange, CA),和有含去球體區域(ball reduction band)之單晶型托架(Inspire Ice, Ormco, Orange, CA)以及多晶型的矯正托架(Clarity, 3M Unitek, Monrovia, CA)。矯正托架都是使用上顎第一小臼齒的托架,都是以相同的鍵結樹脂系統黏在已拔下來的人類小臼齒上,所有標本都在攝氏37度的蒸餾水中水浴隔夜。 在第一部份的實驗,每一種托架各以十個標本,由同一位操作者由手工操作的方式遵照廠商所建議去鍵結的方法來去鍵結以便模擬臨床。Clarity使用How pliers,Inspire和Inspire Ice則使用廠商提供的拋棄式特殊塑膠鉗來移除托架。第二部分則是將廠商所建議使用的鉗架在自製模擬臨床去鍵結的標準化模具上,再配合Instron萬用測試機標準化去鍵結步驟,以模擬臨床去鍵結的型態。每一托架各以二十個標本來做實驗,以力量位移圖記錄去鍵結所需的力量。第三部份是用二十個Inspire矯正托架以高頻率超音波之切割模式在托架牙齦端以及兩個線角處,於托架底和牙釉質的交界面作預裂(pre-crack),再以和Inspire托架相同的去鍵結步驟作拆除托架的動作。另外以二十個Clarity矯正托架則在托架近心端和遠心端,於托架底和牙釉質的交界面作預裂,再以和Clarity托架相同的去鍵結步驟作拆除托架的動作。以力量位移圖記錄去鍵結所需的力量。所有牙齒和矯正托架都以立體光學顯微鏡和掃描式電子顯微鏡觀察。 研究結果顯示,第一部分用手去鍵結:三種廠牌的托架呈現的都是一種混合型態的斷裂模式,大多數的斷裂都發生在托架和黏著層的交界面。三種廠牌托架產生托架斷裂且殘留在牙齒表面的比例與組別有顯著相關(p=0.0057)。Inspire,Inspire Ice和Clarity托架分別佔60%、20%和0%,Inspire和Inspire Ice的托架斷裂都發生在托架底部靠咬合面端。在三組中都沒有發生牙釉質斷裂的情形。 第二部分用Instron去鍵結,拆除托架所需要的力量大小,依序Inspire為25.72牛頓,Inspire Ice為17.92牛頓,Clarity為76.89牛頓。三種廠牌的斷裂模式和第一部分相同,以發生在托架和黏著層的交界面為大部分。三種廠牌托架產生托架斷裂且殘留在牙齒表面的比例與組別有顯著相關(p=0.0473)。Inspire,Inspire Ice和Clarity托架分別佔65%、15%和10%。Clarity的托架斷裂發生在托架翼和托架垂直溝槽,Inspire和Inspire Ice的托架斷裂都發生在托架底部靠咬合面端。在三組中都沒有發生牙釉質斷裂的情形。 比較新型含去球體區域的Inspire Ice矯正托架和舊型Inspire托架,顯示顯著減少拆除托架所需的力量(p=0.0125)和降低托架斷裂且殘留在牙齒表面的情形(p=0.0044)。顯示新型的托架設計已有改善部分去鍵結時的問題。 第三部分以超音波作預裂(pre-crack)的部分,拆除托架所需要的力量大小,pre-crack Inspire為16.66牛頓,pre-crack Clarity為39.02牛頓。斷裂模式仍以托架和黏著層的交界面為主。作過超音波預裂的Inspire托架,托架發生斷裂的情形為5%;作過預裂的Clarity托架,沒有托架發生斷裂。兩組都沒有牙釉質斷裂的情形發生。 作過超音波預裂的Inspire托架和原始的Inspire托架相比,顯示顯著減少拆除托架所需的力量(p=0.0039)和降低托架斷裂且殘留在牙齒表面的情形(p=0.0012)。作過超音波預裂的Clarity托架和原始的Clarity托架相比,亦顯示顯著減少拆除托架所需的力量(p=0.0015)和降低托架斷裂且殘留在牙齒表面的情形(p=0.0471)。結果顯示在托架底部和牙釉質之交界面以超音波作預裂,不需犧牲鍵結強度(bonding strength),但在去鍵結時,又可以較小的力量達到去鍵結,顯著降低托架斷裂且殘留在牙齒表面的比例,又無牙釉質斷裂的發生,可有效減少陶瓷矯正托架去鍵結時的問題,是一值得繼續發展和研究的去鍵結技術。 Ceramic brackets were developed because of requirements for good esthetics. Ceramics are very hard and brittle. The combinations of these properties and high bond strengths have led to significant problems. Reports of bracket fracture and enamel damage during debonding have raised questions about the safety of the various procedures used to remove these brackets. The various manufactures have therefore been continued to modify the base designs of ceramic brackets and have introduced new debonding techniques for each particular brand of bracket. The objectives of this study were to evaluate in vitro debonding forces and failure modes of currently used ceramic brackets bonded to enamel with a dual-cured orthodontic adhesive. Conventional monocrystalline ceramic brackets (Inspire, Ormco, Orange, CA), a new design of monocrystalline ceramic brackets with a ball reduction area (Inspire Ice, Ormco, Orange, CA), and polycrystalline ceramic brackets (Clarity, 3M Unitek, Monrovia, CA) were bonded to extracted human premolars using the same bonding system. Brackets for the upper first premolars were chosen in this study. All bonded specimens were placed in distilled water overnight at 37˚C and were randomly assigned to 3 parts of the experiment. In part 1, 30 specimens, 10 of each type, were removed with debonding pliers recommended by the manufacturers. Inspire and Inspire Ice ceramic brackets were removed by a set of disposable plastic pliers that suggested by the manufacturer. Clarity ceramic brackets were removed using How pliers. In part 2, 60 specimens, 20 of each type, were used in the test. All specimens were tested on an Instron universal testing machine to determine the debonding force and to standardize debonding procedures. A specially designed set-up with disposable plastic pliers was used to debond the Inspire and Inspire Ice brackets to simulate clinical debonding procedures. Another set-up and How pliers were used to debond the Clarity ceramic brackets. In part 3, 20 Inspire and 20 Clarity ceramic brackets were used. An ultrasonic tip with a cutting mode was used to make pre-cracks at the gingival side and 2 gingival line angles of the Inspire brackets between the base of the bracket and the enamel. The debonding procedure was the same as that of the Inspire ceramic brackets. The ultrasonic tip was used to make pre-cracks at the mesial and distal sides of the Clarity brackets between the base of the bracket and the enamel. The debonding procedure was the same as that of the Clarity ceramic brackets. All teeth were examined using optical microscopy and scanning electron microscopy. The following results were obtained. In part 1, all groups showed a mixed mode of failure when examined under scanning electron microscope (SEM). Most of the test brackets failed at the bracket-adhesive interface. A cohesive bracket fracture and remains on the enamel surface were noted for all three types of ceramic brackets (60% of Inspire, 20% of Inspire Ice and 0% of Clarity). The ceramic fractures of Inspire and Inspire Ice were located on the occlusal aspect of the base. No enamel damage was found after the brackets were removed. In part 2, the mean debonding forces of Inspire, Inspire Ice and Clarity were 25.72, 17.92, and 76.89 N, respectively. All groups showed a mixed mode of failure when examined under SEM. Most of the test brackets failed at the bracket-adhesive interface. A cohesive bracket fracture and remains on the enamel surface were noted for all three types of ceramic brackets (65% of Inspire, 15% of Inspire Ice and 10% of Clarity). The cohesive ceramic fractures of Clarity were located at the wing and at the vertical debonding slot. The ceramic fractures of Inspire and Inspire Ice were located on the occlusal aspect of the base. No enamel damage was found after the brackets were removed. The results of a comparison of the Inspire and Inspire Ice ceramic brackets indicated that a significantly reduced force was needed to remove the Inspire Ice brackets(p=0.0125)and risk of bracket fracture during debonding was also reduced (p=0.0044). Therefore, the new design of Inspire Ice ceramic brackets with a ball reduction band may reduce part of the problems of debonding. In part 3, the mean debonding forces of the pre-cracked Inspire and pre-crack Clarity brackets were 16.66 and 39.02 N, respectively. All groups showed a mixed mode of failure when examined under SEM. Most of the test brackets failed at the bracket-adhesive interface. Cohesive ceramic bracket fracture and fractures remaining on the enamel surface was found 5% of the pre-cracked Inspire ceramic brackets and 0% of the pre-cracked Clarity ceramic brackets. Ceramic fractures of the pre-cracked Inspire brackets were located on the occlusal aspect of the base. No enamel damage was found after the brackets were removed. The results of a comparison between the pre-cracked Inspire and the conventional Inspire ceramic brackets indicated that a significantly reduced force was needed to remove the pre-cracked brackets(p=0.0039)and reduced risk of bracket fracture during debonding(p=0.0012). Results of a comparison between the pre-cracked Clarity and the conventional Clarity ceramic brackets also significantly reduced force needed to remove the bracket(p=0.0015)and that was reduced risk of bracket fracture during debonding (p=0.0471). Pre-cracking at the bracket-enamel interface by cutting with a ultrasonic tip is helpful to reduce the debonding force and the risk of bracket fracture. No enamel damage was noted under SEM when ultrasonic used. This technique is helpful in reducing problems of debonding and is worthy of further development. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/35046 |
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顯示於系所單位: | 臨床牙醫學研究所 |
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