CAD/CAM一体化纤维桩核修复薄弱根管的冠向微渗漏研究

目的：观察计算机辅助设计与制作（CAD／CAM）一体化纤维桩核修复薄弱根管的冠向微渗漏大小。方法：选择单根管前磨牙60颗,完善根管治疗后制备成薄弱根管形态。分组制作粘接 CAD／CAM一体化纤维桩核（A 组）、预成单支纤维桩＋流体树脂核（B 组）和铸造金钯金属桩核（C 组）,每组20颗。印度墨水染色4周后脱矿脱水透明化处理,体视显微镜下观察染料渗入情况并分析统计学差异。再将标本完全脱矿,观察微渗漏产生的界面。结果：3种桩核修复薄弱根管后根管壁与桩核之间均存在微渗漏,A 组与 C 组冠方微渗漏无显著性差异（P ＞0．05）,均明显小于 B 组（P ＜0．05）。A 组、C 组微渗漏多产生在桩核与树脂水门汀之间,B 组则多出现于树脂水门汀与根管壁之间。结论：CAD／CAM一体化纤维桩核修复薄弱根管的冠方微渗漏多产生于桩核与粘接剂界面,大小与金属桩组相似且均明显小于单支纤维桩＋树脂核组。     

两种粘接剂粘固铸造桩核后备牙时机对冠方微渗漏影响的研究

目的：比较两种粘接剂粘固铸造金属桩核及粘固后不同间隔时间预备对冠方微渗漏的影响。方法：60颗离体单根管下颌前磨牙行截冠、根管预备和充填后制作铸造桩核,随机分为A、B两组,每组30颗,A组为玻璃离子水门汀粘接剂组,B组为树脂粘接剂组。每组再随机分为1、2、3三个亚组,每组10颗,其中A1、A2、B1、B2为实验组,分别在桩核粘固后5min、30min开始备牙,A3、B3组作为对照组,桩核粘固后不进行预备。所有样本浸入印度墨水染色两周后沿近远中向纵行剖开,在体视显微镜下观察冠方微渗漏情况。结果：A1、A2组微渗漏差异无统计学意义（p〉0．05）,但均大于A3组（p〈0．05）;B2、B3组微渗漏差异无统计学意义（P〉0．05）,均小于B1组（P〈0．05）;A1组微渗漏大于B1组、A2组大于B2组（P〈0．05）,A3、B3组微渗漏差异无统计学意义（P〉0．05）。结论：玻璃离子粘固铸造桩核后备牙间隔时间应大于30min,树脂粘固后备牙间隔时间可为30mill;相同间隔时间备牙时,高速手机振动对树脂粘接剂冠方微渗漏影响小于玻璃离子水门汀。     

不同根管封闭剂及清洗方法对纤维桩粘接强度的影响

目的 研究不同根管封闭剂和清洗方法对纤维桩粘接强度的影响,探讨二者对纤维桩粘接强度是否存在交互影响作用。方法 48颗离体下颌前磨牙行完善根管治疗后,根据根管封闭剂随机分为两组,A组采用Endofil封闭剂（丁香酚类）,B组采用AH-plus封闭剂（树脂类）。桩道预备后每组再根据根管清洗方法分为3个亚组（每组8颗）：A1、B1组采用0.9%NaCl溶液清洗;A2、B2组采用17%乙二胺四乙酸（EDTA）+5.25%NaClO+0.9%NaCl溶液清洗;A3、B3组采用17%EDTA+5.25%NaClO+0.9%NaCl溶液+超声清洗。采用RelyX^TMUnicem树脂粘接剂黏固纤维桩1周后,行薄片推出实验。对结果进行三因素方差分析及Turkey检验。采用扫描电子显微镜（SEM）观察根管内壁的超微形态。结果 6组的纤维桩粘接强度分别为A1组（7.96±2.23） MPa,A2组（9.95±2.89）MPa,A3组（18.88±3.69）MPa,B1组（11.41±3.71）MPa,B2组（14.00±4.04）MPa,B3组（19.14±3.27）MPa。三因素方差分析表明：不同的根管封闭剂与清洗方法具有交互作用（P<0.05）; B1组粘接强度大于A1组,B2组大于A2组（P<0.05）,B3与A3组无明显差异（P>0.05）。SEM显示A3、B3组的根管内壁玷污层最少,牙本质小管完全开放。结论 采用0.9%NaCl溶液、17%EDTA+5.25%NaClO+0.9%NaCl溶液清洗根管时,使用丁香酚类根管封闭剂较树脂类根管封闭剂的纤维桩粘接强度降低;超声联合17%EDTA+5.25%NaClO+0.9%NaCl溶液清洗根管,两种根管封闭剂对纤维桩粘接强度的影响无明显差异。     

三种桩封闭根管冠方能力的实验研究

目的 研究纤维桩与金属桩根管冠方封闭能力的差异.方法 45颗离体前牙根管充填后随机分成A、B、C组,每组15颗牙齿.分别用石英纤维桩(A组)、预成金属螺纹桩(B组)和铸造平滑桩(C组)进行修复.经30万次负荷加载后制成透明标本,显微镜下观察并测量每组标本冠方的微渗漏长度,对数据进行统计分析.结果 A组15颗牙只观察到2颗渗漏,螺纹桩组和铸造桩组30颗牙全部发生渗漏.平均渗漏长度:A组为(0.057±0.168)mm;B组为(2.136±0.678)mm;C组为(2.358±0.838)mm,方差分析结果表明3组之间差异有统计学意义,F=315.491,P<0.001.结论 纤维桩对根管冠方的封闭能力优于金属桩.     

比较2种根管充填糊剂对根尖封闭性的作用

目的用染料渗透法测量根管微渗漏的程度,比较2种根管充填糊剂在根管充填后不同时间进行桩腔预备后对根尖部的封闭能力。方法选取90颗成人的上颌中切牙,逐步后退法预备根管,侧向加压技术充填根管,充填剂分别用Cortisomol糊剂（A组）和氧化锌丁香油糊剂（B组）,每组45颗上颌中切牙。根据根管充填后桩腔预备时间将A组上颌中切牙随机分为A1组、A2组和A3组,每组15颗,A1组为根管充填后即刻进行桩腔预备,A2组为根管充填后2周进行桩腔预备,A3组为根管充填后4周进行桩腔预备。根据根管充填后桩腔预备时问将B组上颌中切牙随机分为B1组、B2组和B3组,每组15颗,B1组为即刻进行桩腔预备,B2组为根管充填后2周进行桩腔预备,B3组为根管充填后4周进行桩腔预备。进行桩腔预备后用染料渗透法评价各组根尖渗透能力。结果Cortisomot组（A组）与氧化锌丁香油组（B组）在根管充填后相同时间进行桩腔预备后,根尖微渗漏的差异具有统计学意义（P〈0．01）。A组在根管充填后即刻、2周、4周时进行桩腔预备,其根尖微渗漏的差异具有统计学意义（P〈0．01）。B组在根管充填后即刻、2周、4周时进行桩腔预备,其根尖微渗漏的差异无统计学意义（P〉0．05）。结论Cortisomol根管充填糊剂的封闭作用效果比氧化锌丁香油糊剂好。     

不同冲洗剂对桩腔预备后牙本质清洗能力及树脂突的影响

目的比较不同根管冲洗剂对桩腔预备后根管内牙本质表面玷污层去除和牙本质小管开放的影响。方法将30个完成根管充填的上颌前牙经桩腔预备后,根据根管冲洗剂不同随机分成A、B、C 3组。A、B、C组分别使用3%过氧化氢（H2O2）、15%乙二胺四乙酸（EDTA）、15%EDTA加3%次氯酸钠（NaClO）作为冲洗剂。冲洗后每组选取8个标本通过扫描电镜（SEM）观察牙本质表面玷污层和牙本质小管开放情况,另选2个标本在粘接纤维桩后用于观察树脂突。结果A、B、C组牙本质清洁效果（Berg值）分别为3.89±0.36、1.77±0.30、1.25±0.21;牙本质小管直径分别为（2.53±0.19）、（3.11±0.23）、（3.83±0.52）μm。3组间牙本质表面清洁效果和牙本质小管开口差异均有统计学意义（P<0.05）。C组出现明显的牙本质过蚀。各组间的树脂突形成有很大差异,以B组最优。结论桩腔预备后用15%EDTA冲洗桩腔能有效去除玷污层,使牙本质小管开放,利于树脂黏固剂有效渗入牙本质小管和胶原纤维网。     

MTAD作为根管冲洗剂的效果评价

目的探讨应用MTAD作为根管冲洗剂去除根管壁玷污层的效果,以及对根管充填后根尖微渗漏的影响。方法采集因正畸或牙周病拔除的前磨牙,截冠后统一工作长度16 mm,按照冲洗液使用的不同,随机分为A、B、C 3组,每组12颗。A:生理盐水;B:MTAD;C:5.25%NaClO+15%EDTA。采用机用Protaper镍钛根管锉进行根管机械预备,分别用相应冲洗液冲洗,根管预备后每组4颗牙齿用于制备扫描电镜标本,观察根管表面玷污层和牙本质小管暴露的情况。每组剩余8颗进行根管充填,1周后,采用液体转移法,测量各样本根管微渗漏。实验数值采用SPSS 19.0软件包进行分析。结果 A组沉积大量玷污层,牙本质小管被遮蔽,B、C组玷污层得到有效的清除,牙本质小管开放。根管充填后,A组和B组之间,A组和C组间的微渗漏值有统计学差异(P<0.05),B组合C组之间无统计学差异(P>0.05),其中A组的微渗漏值最大。结论 MTAD冲洗剂可以替代5.25%NaClO+15%EDTA联用,能有效地去除根管充填过程中产生的玷污层,增强根管充填后的根尖封闭性。     

桩道预备及桩核修复对根尖封闭性的影响

目的比较即刻、延迟桩道预备及桩核修复对根尖封闭性的影响。方法选择60颗离体下颌单根管前磨牙,使用ProTaper镍钛锉和冠向下法进行根管预备。将样本分为5组,除阳性对照组外其余样本均用AH-Plus封闭剂、侧方加压法进行根管充填。A组为即刻桩道预备组,B组为延迟桩道预备组,C组为无桩道预备组,D组为阳性对照组,E组为阴性对照组。其中A、B组再各分为2个亚组,A1、B1组为桩道预备后采用暂封材料封闭,A2、B2组为桩道预备后立即行纤维桩核修复。使用印度墨水染色法测定各组牙齿的根尖微渗漏情况,体视显微镜下测量染料渗入根管内壁的长度,并行统计学分析。结果A1、A2、B1、B2、C组染料渗入长度分别为（0.52±0.47）、（0.49±0.44）、（1.17±0.77）、（1.12±0.54）、（0.23±0.40）mm,阳性对照组染料渗入根管全长,阴性对照组无染料渗入。经统计学分析,A1与A2、B1与B2组间染料渗入长度没有统计学差异（P>0.05）;但B1、B2组的染料渗入长度与A1、A2、C组间的差异有统计学意义（P<0.05）,B组渗入长度较长;A1、A2和C组间的差异无统计学意义（P>0.05）。结论延迟桩道预备会削弱充填材料及AH-Plus封闭剂封闭根尖的能力。     

不同方法预备根管对根管治疗后牙齿冠渗漏的影响

目的采用3种不同方法预备根管,评价其对根管治疗后牙齿冠渗漏的影响。方法48颗单根管离体牙随机分为4组,使用不同的根管预备方法去除根管壁的玷污层。A组为对照组,采用生理盐水和过氧化氢溶液冲洗根管;B组采用乙二胺四乙酸（EDTA）凝胶和5.25%次氯酸钠溶液冲洗;C组采用Odontoson-M型超声波治疗仪荡洗;D组采用脉冲Nd: YAG激光照射。每组取2颗牙,于扫描电子显微镜（SEM）下观察冠部玷污层的去除情况;其余10颗牙采用Obtura Ⅱ高温注射式热牙胶垂直加压法充填根管,氧化锌丁香油黏固剂封闭根管口,浸于质量浓度20 g·L-1亚甲基蓝溶液中染色7 d,脱水脱钙制作透明牙标本,体视显微镜下测量染料渗入的深度。结果SEM观察：A组
整个根管内壁被覆玷污层及大量碎屑,牙本质小管被堵塞;B组与C组根管内壁清洁,玷污层消失,牙本质小管开放;D组根管内壁牙本质小管封闭或半封闭,玷污层熔融消失。A、B、C、D组染料渗入深度分别为（2.15±0.38）、（1.75±0.28）、（2.04±0.40）、（1.73±0.36）mm。A组的渗入深度明显高于B、D组,其差异有统计学意义（P<0.05）。结论使用不同的方法预备根管去除玷污层,可以减少根管治疗后牙齿的冠渗漏。     

不同桩核系统及根管重塑对漏斗形根管下颌前磨牙抗折特性的研究

目的探讨不同桩核及根管重塑对漏斗形根管下颌前磨牙抗折特性的影响。方法将36颗离体下颌前磨牙随机分为A、B、C、D共4组,每组9颗。A、B、C组设为实验组,预备成漏斗形根管,A组用预成玻璃纤维桩复合树脂核修复,B组用预成钛合金平行螺纹桩复合树脂核修复,C组用复合树脂根管重塑铸造桩核修复;D组（对照组）采用正常根管预备,行铸造桩核修复。桩核修复后,4组均行铸造全冠修复。在电子万能试验机上以与牙体长轴成30°方向,以1 mm·min-1速度加载至样本折裂,分析4组样本的抗折载荷和折裂模式。折裂模式分为可修复性和不可修复性。对抗折载荷行单因素方差分析,对折裂模式采用Fisher′s确切概率法分析。结果A、B、C、D组的抗折载荷分别为（1.39±0.56）、（1.17±0.40）、（1.21±0.30）、（1.31±0.56）kN,4组间的差异无统计学意义（P>0.05）。A、B、C、D组产生不可修复性折裂的样本分别为6、8、9、9颗,4组间折裂模式的差异也无统计学意义（P>0.05）。结论不同桩核系统对下颌前磨牙漏斗形根管残根的抗折特性没有影响,复合树脂重塑可作为漏斗形根管残根修复的一种选择。     

Microleakage and marginal gap of adhesive cements for noble alloy full cast crowns

Very limited comparative information about the microleakage in noble alloy full cast crowns luted with different types of adhesive resin cements is available. The purpose of this study was to evaluate the microleakage and marginal gap of two self-adhesive resin cements with that of other types of adhesive luting cements for noble alloy full cast crowns. Fifty noncarious human premolars and molars were prepared in a standardized manner for full cast crown restorations. Crowns were made from a noble alloy using a standardized technique and randomly cemented with five cementing agents as follows: 1) GC Fuji Plus resin-modified glass ionomer cement, 2) Panavia F 2.0 resin cement, 3) Multilink Sprint self-adhesive resin cement, 4), Rely X Unicem self-adhesive resin cement with pretreatment, and 5) Rely X Unicem with no pretreatment. The specimens were stored in distilled water at 37°C for two weeks and then subjected to thermocycling. They were then placed in a silver nitrate solution, vertically cut in a mesiodistal direction and evaluated for microleakage and marginal gap using a stereomicroscope. Data were analyzed using a nonparametric Kruskal-Wallis test followed by Dunn multiple range test at a p<0.05 level of significance. The Rely X Unicem (with or with no pretreatment) exhibited the smallest degree of microleakage at both tooth-cement and cement-crown interfaces. The greatest amount of microleakage was found for Panavia F 2.0 resin cement followed by GC Fuji Plus at both interfaces. No statistically significant difference in the marginal gap values was found between the cementing agents evaluated (p>0.05). The self-adhesive resin cements provided a much better marginal seal for the noble alloy full cast crowns compared with the resin-modified glass ionomer or dual-cured resin-based cements.     

Influence of marginal fit and cement types on microleakage of all-ceramic crown systems

The purpose of this study was to evaluate the effects of both marginal fit and cementing with different luting agents on the microleakage of all-ceramic crown systems. Thirty-six extracted upper central incisors were prepared for full-coverage crowns and were divided into three groups. Group 1: CAD/CAM-fabricated ZrO2, Group 2: Heat-pressed lithium-disilicate, and Group 3: Cast Cr-Co copings as the control group. Copings were made following standard techniques, and groups were assigned cementation with either self-adhesive resin cement (A) or glass-ionomer luting cement (B). The specimens were subjected to thermocycling, immersed in basic fuchsin solution, sectioned mesiodistally and buccolingually. The surface of each section was digitally photographed under a stereomicroscope. Microleakage was scored using a five-point scale, and the marginal gap was measured using image analysis software. Data were statistically analyzed using 2-way ANOVA, Kruskal-Wallis, and Mann-Whitney U tests (α: 0.05). The marginal discrepancy of each group was 82.7 ± 7 μm, 92.6 ± 4 μm and 96.5 ± 7 μm respectively. Group 1 showed significantly smaller gaps than Group 3 (P = 0.042). Self-adhesive resin cement (A) showed a lower level of microleakage than glass-ionomer luting cement (B) in all groups (P = 0.029). Microleakage scores of '0' were 83% for 1A, 50% for 1B, 50% for 2A, 16% for 2B, 33% for 3A and none for 3B. Marginal discrepancy and cement type both had significant effects on microleakage. Lower levels of microleakage were recorded with self-adhesive resin cement, while CAD/CAM-fabricated ZrO2 copings showed smaller marginal discrepancy and less microleakage in comparison to cast Cr-Co.     

三种水门汀粘接纵裂磨牙封闭效果的体外研究

目的:评价纵裂磨牙应用3种水门汀进行粘接内固定的实验效果,并观察裂隙内的微渗漏情况。方法:选用人离体磨牙60颗,随机分为新鲜纵裂组和陈旧纵裂组,分别为裂隙密合和面裂隙保持2mm间隙。后将两组牙齿分别以玻璃离子、自粘接树脂水门汀Unicem和超级粘接剂粘接纵裂的裂隙(n=10),待材料凝固后行全冠牙体预备,观察预备体是否会复裂,并以树脂冠修复。全部试件置入37℃生理盐水中7d,并4℃-55℃冷热循环500次后,放置于0.5%的品红溶液中染色7d,观察裂隙封闭程度并在根管显微镜下观察微渗漏情况,采用SPSS 17.0软件包对数据进行统计学处理。结果:新鲜纵裂组中,牙体预备后均未复裂,超级粘接剂能完全封闭裂隙,Unicem和玻璃离子均不能渗入裂隙,染料渗入长度分别为(1.28±0.43)mm、(2.36±0.35)mm和(3.64±0.95)mm,三组间差异有统计学意义(P<0.05);陈旧纵裂组中,牙体预备后均未复裂,超级粘接剂能完全封闭裂隙,Unicem和玻璃离子均不能渗入到根尖,染料渗入长度分别为(2.15±0.40)mm、(3.13±0.81)mm和(3.85±0.70)mm,三组间差异有有统计学意义(P<0.05)。结论:相对于玻璃离子和树脂水门汀Unicem,超级粘接剂在粘接固定纵裂磨牙时的流动渗入能力较好,边缘微渗漏较少。     

Tensile bond strength of glass fiber posts luted with different cements

Proper selection of the luting agent is fundamental to avoid failure due to lack of retention in post-retained crowns. The objective of this study was to investigate the tensile bond strength and failure mode of glass fiber posts luted with different cements. Glass fiber posts were luted in 40 mandibular premolars, divided into 4 groups (n = 10): Group 1--resin-modified glass ionomer RelyX Luting; Group 2--resin-modified glass ionomer Fuji Plus; Group 3--resin cement RelyX ARC; Group 4--resin cement Enforce. Specimens were assessed by tensile strength testing and light microscopy analysis for observation of failure mode. The tensile bond strength values of each group were compared by ANOVA and Tukey test. The significance level was set at 5%. The failure modes were described as percentages. The following tensile strength values were obtained: Group 1--247.6 N; Group 2--256.7 N; Group 3--502.1 N; Group 4--477.3 N. There was no statistically significant difference between Groups 1 and 2 or between Groups 3 and 4, yet the resin cements presented significantly higher tensile bond strength values than those presented by the glass ionomer cements. Group 1 displayed 70% of cohesive failures, whereas Groups 2, 3 and 4 exhibited 70% to 80% of adhesive failures at the dentin-cement interface. We concluded that resin cements and glass ionomer cements are able to provide clinically sufficient retention of glass fiber posts, and that glass ionomer cements may be especially indicated when the application of adhesive techniques is difficult.     

不同粘接剂对金属烤瓷冠边缘微渗漏影响的研究

目的 评价4种不同粘接剂在金属烤瓷冠修复中的微渗漏情况.方法 制作16个金属烤瓷冠,随机分成4组,分别采用玻璃离子黏固剂、树脂加强玻璃离子黏固剂、PanaviaF粘接剂和super-Bond C&B粘接剂黏固于前磨牙,经温度循环试验后,将样本浸入2%品红溶液中24 h,用体视显微镜观察牙-黏固剂界面边缘微渗漏状况,并进...     

SEALING ABILITY OF CEMENTS IN ROOT CANALS PREPARED FOR INTRARADICULAR POSTS

This research evaluated the sealer ability of 2 temporary filling materials (white Cimpat and IRM) and 1 restorative cement (glass ionomer), in canals prepared for root posts. Sixty human palatal roots of maxillary first molars were used. They were divided into 3 groups, according to the cements used: Group I (Cimpat), Group II (IRM) and Group III (glass ionomer). The roots were rendered impermeable, filled with the respective cements and soon after immersed into 0.2% Rhodamine B dye and maintained for 72 hours in an oven for 37°C. Microleakage was measured with a light microscope, cutting the roots longitudinally in buccolingual direction. The results showed that Group I presented significantly more leakage than Groups II and III, which were not significantly different from each other.     

In vitro shear bond strength of cementing agents to fixed prosthodontic restorative materials

STATEMENT OF PROBLEM: Durable bonding to fixed prosthodontic restorations is desirable; however, little information is available on the strength of the bond between different cements and fixed prosthodontic restorative materials. PURPOSE: This study determined the shear-bond strength of cementing agents to high-gold-content alloy castings and different dental ceramics: high-strength aluminum oxide (Procera AllCeram), leucite-reinforced (IPS Empress), and lithium disilicate glass-ceramic (IPS Empress 2). MATERIAL AND METHODS: Prepolymerized resin composite cylinders (5.5 mm internal diameter, n=20) were bonded to the pretreated surfaces of prosthodontic materials. High-gold-content alloy and high-strength aluminum oxide surfaces were airborne-particle-abraded, and pressable ceramics were hydrofluoric acid-etched and silanized prior to cementing. The cementing agents tested were a zinc-phosphate cement (Fleck's zinc cement), glass ionomer cements (Fuji I, Ketac-Cem), resin-modified glass ionomer cements (Fuji Plus, Fuji Cem, RelyX Luting), resin cements (RelyX ARC, Panavia F, Variolink II, Compolute), and a self-adhesive universal resin cement (RelyX Unicem). Half the specimens (n=10) were tested after 30 minutes; the other half (n=10) were stored in distilled water at 37 degrees C for 14 days and then thermal cycled 1000 times between 5 degrees C and 55 degrees C prior to testing. Shear-bond strength tests were performed using a universal testing machine at a constant crosshead speed of 0.5 mm/min. Statistical analysis was performed by multifactorial analysis of variance taking interactions between effects into account. For multiple paired comparisons, the Tukey method was used (alpha=.05). RESULTS: In a 3-way ANOVA model, the main factors substrate, cement, time, and all corresponding interactions were statistically significant (all P <.0001). In subsequent separate 1-way or 2-way ANOVA models for each substrate type, significant differences between cement types and polymerizing modes were found (all P <.001). None of the cement types provided the highest bonding values with all substrate types. CONCLUSION: After 14 days of water storage followed by thermal cycling, only the self-adhesive universal resin cement (RelyX Unicem) and 2 of the resin cements (Panavia F and Compolute) exhibited strong bond strengths to specific prosthodontic materials. In contrast, zinc-phosphate, glass ionomer, and resin-modified glass ionomer cements showed the lowest values of all tested cementing agents after 14 days of water storage followed by thermal cycling.     

Microleakage on Class V glass ionomer restorations after cavity preparation with aluminum oxide air abrasion

This in vitro study assessed the marginal microleakage on class V cavities prepared with aluminum oxide air abrasion and restored with different glass ionomer cements. The cavities were prepared on the buccal and lingual surfaces of 15 sound third molars with an air- abrasion device (Kreativ Mach 4.1; New Image) using a 27.5-microm aluminum oxide particle stream, and were assigned to 3 groups of 10 cavities each. The restorative materials were: group I, a conventional glass ionomer cement (Ketac-Fil); groups II and III, resin-modified glass ionomer cements (Vitremer R and Fuji II LC, respectively). After placement of the restorations, the teeth were stored in distilled water at 37 degrees C for 24 h, polished and then submitted to a thermocycling regimen of 500 cycles, isolated, immersed in 0.2% Rhodamine B solution for 24 h, included and serially sectioned. Microleakage was assessed by viewing the specimens under an optical microscope connected to a color video camera and a computer. The images obtained were digitized and analyzed for microleakage using software that allows for a standard quantitative assessment of dye penetration in millimeters. Statistical analysis was done using the Kruskall-Wallis and Wilcoxon tests. Means of dye penetration (%) were: occlusal - I: 25.76 +/- 34.35, II: 20.00 +/- 42.16, III: 28.25 +/- 41.67; cervical - I: 23.72 +/- 41.84; II: 44.22 +/- 49.69, III: 39.27 +/- 50.74. No statistically significant differences (p>0.05) were observed among either the glass ionomer cements or the margins. In conclusion, class V cavities restored with either conventional or resin-modified glass ionomer cements after preparation with aluminum oxide air abrasion did not show complete sealing at the enamel and dentin/cementum margins.     

应用扫描电镜对金属烤瓷冠不同粘接剂边缘微渗漏的比较研究

目的:评价不同粘接剂粘固金属烤瓷冠的边缘微渗漏情况,为临床选择粘接剂提供实验依据.方法:选取传统的玻璃离子粘接剂、树脂加强型玻璃离子粘接剂、Panavia F粘接剂和Super-Bond C&B粘接剂4种材料,应用于离体牙金属烤瓷冠的粘接,用扫描电镜测量粘接剂与牙组织面间微缝隙的缝隙宽度.数据处理用SPSS 11.5软...     

An In Vitro Evaluation of the Microleakage under Complete Metal Crowns Using Three Adhesive Luting Cements

Despite the material advancements and precise laboratory techniques, cement lines are inevitable in fixed prosthodontics which leads to increased dependence on the integrity of the cement to maintain the marginal seal. The material class of luting agent is known to influence microleakage. Studies of cement dissolution and disintegration have produced varying results. Hence, this study was done to evaluate marginal leakage under complete metal crowns using three adhesive cements, two resin cements (one self cure, one dual cure) and a glass ionomer cement. Metal crowns were prepared on sixty intact extracted premolars and were randomly divided into three groups of twenty each, with each group using a different cement for luting. All the samples were then subjected to thermocycling and were sectioned using a diamond saw. Reflected Binocular Stereomicroscope at 100× magnification was used to study the extent of microleakage at both metal cement (MC) and tooth cement (TC) interface, at two opposite margins of each sectioned specimen. Data was analyzed with a one way analysis of variance. For comparison among the groups multiple comparison Bonferroni test was done. Within group data was analysed with independent student t test. Between three groups, metal crowns cemented with multilink cement showed significantly less microleakage at both the interfaces. Glass ionomer cement recorded maximum combined microleakage amongst three cements irrespective of the interfaces. Within group, glass ionomer and multilink cement showed more microleakage at MC interfaces than at TC interface. A complex interaction between variables related to dental restoration, luting agent and tooth structure probably influence microleakage. In vitro studies must always be followed by in vivo studies before definite conclusion can be drawn.