Er, Cr: YSGG激光照射后牙体硬组织抗酸性变化的研究

目的 对Er，Cr：YSGG激光照射后牙体硬组织人工龋蚀的抗酸性变化进行体外研究，为其临床应用提供有价值的理论依据。方法 牙釉质标本采用6W，牙本质标本采用4W Er，Cr：YSGG激光照射6s，0．1mol／L乳酸脱矿，原子吸收分光光度计检测脱矿液中溶解的钙离子浓度，能谱分析仪进行原子含量分析，扫描电镜观察牙体硬组织表面结构变化。结果 Er，Cr：YSGG激光照射后牙釉质和牙本质的钙离子溶出浓度均显著低于对照组，钙含量在牙釉质和牙本质均显著高于对照组，磷含量在牙釉质和牙本质标本中都增高，但仅在牙釉质组差异有统计学意义，钙／磷重量比差异均无统计学意义。激光照射后釉质表面不平呈鳞片状，无玷污层，釉质结构清晰可见；牙本质小管开放，无熔融及碳化。结论 Er，Cr：YSGG激光照射后牙体硬组织抗酸性增强，而且激光照射不对牙体硬组织造成热损伤。     

Er,Cr:YSGG激光制备对牙体抗剪切强度影响的实验研究

目的　比较Er,Cr:YSGG激光与传统高速手机两种切割方法对牙体抗剪切强度的影响 ,分析Er,Cr:YSGG激光是否可以提高牙面的黏结强度。方法　选取新鲜离体牛上中切牙 4 6颗 ,分为两组 ,分别采用Er,Cr :YSGG激光和高速手机切割牙体。通过分组对照 ,进行抗剪切强度实验、扫描电镜观察、能谱分析及X线衍射分析。结果　Er,Cr:YSGG激光组的抗剪切强度高于高速手机组 (P <0 .0 0 1) .扫描电镜下观察 ,激光组的牙体表面清洁、粗糙 ,无玷污层存在 ,牙本质小管口开放 ,无裂化、熔融等热损伤迹象 ;能谱分析与X线衍射分析结果表明 ,两组样本在表面成分、结构上无明显差异。结论　Er,Cr:YSGG激光制备牙体不会引起牙体组织成分及结构的改变 ;Er,Cr:YSGG激光制备后的牙体抗剪切强度高于高速手机制备后的牙体 ,Er,Cr:YSGG激光制备牙体可以提高牙体的黏接强度。     

Er,Cr:YSGG激光照射对牙本质玷污层的清除作用

目的 :观察不同能量与照射距离的Er ,Cr :YSGG激光照射后 ,牙本质表面形态变化和玷污层的去除情况。方法 :选用离体第一前磨牙 ,金刚砂片垂直于牙长轴在冠中 1/3处横断 ,制 1.5mm厚牙片 ,不同照射距离 ( <2mm ,3mm) ,不同能量 ( 1、2、3、4、6W )激光照射牙本质 ,常规制SEM标本后扫描电镜观察。结果 :照射距离 <2mm ,2～ 6W能量的激光均能有效去除牙本质表面玷污层 ,牙本质小管管径减小或部分封闭 ,随着能量增高 ,管间牙本质去除逐渐增多 ;照射距离 3mm时 ,大于 4W的激光也能有效去除玷污层。结论 :照射距离 <2mm ,能量为 2～ 3W ,与照射距离 3mm ,能量大于 4W ,可作为Er ,Cr :YSGG激光用于去除牙本质表面玷污层的参考参数。     

Er,Cr:YSGG激光对乳牙硬组织粘接性能影响的研究进展

Er,Cr:YSGG激光以其能够安全、精确地切割牙体硬组织而成为近年来激光牙科学的研究热点.Er,Cr:YSGG激光照射后牙体硬组织的表面形态、成分及结构均发生改变,这些变化对后续修复材料粘接力的影响目前还存在争议.本文从Er,Cr:YSGG激光用于牙体硬组织切割的机制、乳牙组织的结构特点、Er,Cr:YSGG激光处理对乳牙牙体硬组织粘接力的影响、Er,Cr:YSGG激光在儿童口腔领域应用的安全性、优势及展望做一综述.     

不同能量Er,Cr∶YSGG激光照射对牙体硬组织抗酸作用的体外研究

目的:探讨Er,Cr∶ YSGG激光照射能量与牙体硬组织抗酸性之间的关系.方法:采用2.5、3.5、5W激光照射牙釉质样本,2、3、4W激光照射牙本质样本.经0.1 mmol/L乳酸液浸泡24 h后检测钙磷溶出量,能谱仪检测样本表面钙磷原子百分比,SEM观察表面形态.结果:除2.5W牙釉质组,其余牙釉质和牙本质实验组钙磷溶出量显著低于对照组(P＜0.05),实验组间无明显差异.激光照射后牙釉质钙磷比增加,牙本质钙磷含量均无变化.SEM观察显示实验组样本表面粗糙,釉柱间隙增大,牙本质小管口周牙本管突出成袖口状.结论:一定能量的Er,Cr∶YSGG激光照射可使牙硬组织抗酸性提高.     

Er,Cr:YSGG激光在根管治疗中的应用进展

铒、铬:钇钪镓石榴石(erbium,chromium:yttrium scandium gallium garnet laser,Er,Cr:YSGG)激光在牙科领域主要应用于根管治疗术、牙周疾病、龋病、牙本质过敏症、牙髓切断术等。本文从根管封闭性、灭菌、空穴效应和对根尖周组织影响四个方面对Er,Cr:YSGG激光在根管治疗中的研究进展作一综述。文献复习结果表明,Er,Cr:YSGG功率为2~4 w,20 Hz时,可以较好清除牙本质小管玷污层,从而提高材料与牙本质之间的密闭性;Er,Cr:YSGG能量产生的热效应具有灭菌作用,而牙体的光导性使冲洗液能够进入更深的组织,进一步提高灭菌效果;Er,Cr:YSGG还具有空穴效应,破坏深处溶液的表面张力,从而可以清除深层的玷污层与细菌;但是在相同功率下Er,Cr:YSGG如果使用不当,Er,Cr:YSGG产生的热效应会对根尖周组织造成一定伤害,因此,合理的Er,Cr:YSGG使用时间长短和在水冷却条件下是重要的。     

不同参数的Er：YAG激光离体牙窝洞预备的形态学观察

目的：观察Er：YAG激光对离体人牙进行窝洞预备后的形态学改变,比较不同的能量设置及不同的水气比作用下的预备效果。方法：将10个无龋的离体磨牙随机分为5组（n＝2）,分别用不同Er：YAG激光参数进行窝洞预备。扫描电镜下观察牙釉质和牙本质的形态学改变。结果：经Er：YAG激光照射后,牙釉质呈现出一个粗糙不平的表面,牙本质层清洁,小管开放。在总功率相近的情况下,当水冷却降到50％或切割牙釉质时脉冲能量增加到700 mJ、切割牙本质时脉冲能量增加到400 mJ时,牙釉质及牙本质表面可发生部分熔融改变。结论：Er：YAG激光使用合适的参数进行牙体硬组织的切割安全有效,但在功率相近的情况下,水冷却不足或能量过大（牙釉质＞700 mJ,牙本质＞400 mJ）可损伤牙体组织。     

不同能量Er,Cr:YSGG激光照射牙骨质后的形态学分析

目的:观察不同能量的Er,Cr:YSGG激光照射根面后的牙骨质表面形态变化,探讨此激光用于牙周病治疗及根面充填前预处理的可行性。方法:选用离体第一前磨牙,使用水冷却高速钻,釉牙骨质界向下延伸6mm区域,获取厚2mm,面积约6×5mm2标本,不同能量(1、2、3、4、5W)激光垂直照射根面,常规制SEM标本后扫描电镜观察。结果:随着能量的增加,可观察到牙根表面由较为平坦的凹陷至逐渐加深的弹坑样改变,大部分表面玷污层被去除。1W、2W激光照射后,照射区域较为平坦,牙骨质结构完整与清晰,3W、4W组,照射区内(弹坑内部),牙骨质呈现波浪状,片层状外观。5W组可见牙骨质丧失,牙本质小管的暴露。各组均未发现熔融,碳化现象。结论:Er,Cr:YSGG激光照射根面后,可去除牙骨质表面玷污层,并在微观上形成表面凹陷和基底较为平坦的弹坑,低能量的此激光(4W以下)临床上有望用于牙周治疗的根面处理中,1～2W激光更适用于修复前根面的预处理。     

Er.Cr.YSGG激光在龋病治疗中的应用研究

Er．Cr．YSGG激光是新一代水动力生物激光系统,在龋病治疗中的应用正不断深入。本文对其去除龋坏牙体组织的能力、原理,清除玷污层和蚀刻牙体硬组织能力及应用的安全性进行综述。     

Er.Cr:YSGG激光封闭牙本质小管的实验室研究

目的研究Er.Cr:YSGG激光封闭牙本质小管的效果。方法选取新鲜离体的人后牙35颗,制备成70个2 mm×2mm×2 mm牙本质小片,随机分为即刻组和磨损组,两组内除阴性对照不作任何处理外,分别以Gluma脱敏剂,无水条件下0.5、1.5、2.5、3.5、4.5 W的Er.Cr:YSGG激光处理,磨损组则再通过模拟刷牙实验后,用扫描电镜观察。结果随着Er.Cr:YSGG激光输出能量的增加,牙本质表面的碳化现象越明显,牙本质小管开口越来越少,当输出能量为4.5 W时,牙本质小管开口已不可见,即刻组与磨损组未见明显差异。而Gluma脱敏剂处理,即刻组未见牙本质小管开口开口,磨损组牙本质小管开口增多。结论Er.Cr:YSGG激光封闭牙本质小管的作用随着输出能量的增加而逐渐增加,与Gluma脱敏剂相比,封闭效果更为持久。     

Er,Cr:YSGG激光备洞对兔牙髓组织热休克蛋白70表达的影响

目的观察Er,Cr:YSGG激光用于牙体窝洞制备后兔牙髓的形态学变化及热休克蛋白70(heat shockprotein70 HSP70)的表达情况。方法用Er,Cr:YSGG激光在家兔前牙制备V类洞并常规充填,普通高速牙钻备洞作对照,分别于术后4h、24h处死实验动物,组织切片经HE染色及免疫组化染色,镜下观察。结果 Er,Cr:YSGG激光备洞后牙髓轻到中度炎症反应,与牙钻对照组无明显差异。备洞后24h,激光组成牙本质细胞HSP70中到强阳性表达,成纤维细胞、血管内皮细胞中度阳性表达。牙钻组成牙本质细胞及相邻成纤维细胞强阳性表达,血管内皮细胞强阳性表达,对照组HSP70表达高于Er,Cr:YSGG激光实验组,差别有统计学意义(P<0.05)。结论 Er,Cr:YSGG激光备洞对牙髓刺激小,有很好的临床使用价值。     

Atomic analysis and knoop hardness measurement of the cavity floor prepared by Er,Cr:YSGG laser irradiation in vitro

In the present study, the compositional changes and knoop hardness of the cavity floor prepared by Er,Cr:YSGG laser irradiation was compared with that of the conventional bur cavity. Fifteen laser and 15 bur cavities were cross-sectioned, and subjected to atomic analysis by SEM-EDX and knoop hardness test. Statistical analyses were performed using the Mann-Whitney U-test; a value of P < 0.01 was considered significant. Surface characteristics of the prepared cavities were also investigated by light microscopy and scanning electron microscopy (SEM). The results showed that the quantities of Ca (Ca weight %) and P (P weight %) were increased significantly in the laser cavity floor but no significant differences were found between the Ca/P ratio and knoop hardness number of laser and bur cavities. The SEM observation revealed that the lased cavity surface was irregular and there was also the absence of a smear layer; the orifice of dentinal tubules was exposed. Er,Cr:YSGG laser device is considered as one of the most effective and safe devices for cavity preparation because of its many advantages. This includes easy delivery system, minimal thermal damage to the surrounding tissues, minimal thermal-induced changes of dental hard tissue compositions, and favourable surface characteristic.     

A laser-powered hydrokinetic system for caries removal and cavity preparation

BACKGROUND: Laser systems have been developed for the cutting of dental hard tissues. The erbium, chromium:yttrium-scandium-gallium-garnet, or Er,Cr:YSGG, laser system used in conjunction with an air-water spray has been shown to be efficacious in vitro for cavity preparation. METHODS: The authors randomly selected subjects for cavity preparation with conventional air turbine/bur dental surgery or an Er,Cr:YSGG laser-powered system using a split-mouth design. They prepared Class I, III and V cavities, placed resin restorations and evaluated subjects on the day of the procedure and 30 days and six months postoperatively for pulp vitality, recurrent caries, pain and discomfort, and restoration retention. Sixty-seven subjects completed the study. RESULTS: There were no statistical differences between the two treatment groups for the parameters measured with one exception; there was a statistically significant decrease in discomfort levels for the laser system at the time of cavity preparation for subjects who declined to receive local anesthetic. CONCLUSIONS: The Er,Cr:YSGG laser system is effective for preparation of Class I, III and V cavities and resin restorations are retained by lased tooth surfaces. CLINICAL IMPLICATIONS: Hard-tissue cutting lasers are being introduced for use in operative dentistry. In this study, an Er,Cr:YSGG laser has been shown to be effective for cavity preparation and restoration replacement.     

Compositional and structural changes of human dentin following caries removal by Er,Cr:YSGG laser irradiation in primary teeth

In this in vitro study, the compositional and structural changes of human dentin, and knoop harness of cavity floor following the removal of dental caries by Er,Cr:YSGG laser irradiation in primary teeth was compared with that of the conventional bur cavity. The results confirmed that laser irradiation revealed minimal thermal damage to the surrounding tissues, minimal thermal induced changes of dental hard tissue compositions, and favorable surface characteristic.     

Comparative evaluation of surface topography of tooth prepared using erbium,chromium: Yttrium,scandium, gallium,garnet laser and bur and its clinical implications

Background:

Erbium, chromium: Yttrium, scandium, gallium, garnet (Er, Cr: YSGG) laser has been successfully used in the ablation of dental hard and soft tissues. It has been reported that this system is also useful for preparing tooth surfaces and etching, but no consensus exist in the literature regarding the advantage of lasers over conventional tooth preparation technique.

Materials and Methods:

Labial surfaces of 25 extracted human maxillary central incisors were divided into two halves. Right half was prepared with diamond bur and left half with Er, Cr; YSGG laser and a reduction of 0.3–0.5 mm was carried out. Topography of prepared surfaces of five teeth were examined under scanning electron microscope (SEM). The remaining samples were divided into 4 groups of 10 specimens each based on the surface treatment received: One group was acid etched and other was nonetched. Composite resin cylinders were bonded on prepared surfaces and shear bond strength was assessed using a universal testing machine.

Results:

The SEM observation revealed that the laser prepared surfaces were clean, highly irregular and devoid of a smear layer. Bur prepared surfaces were relatively smooth but covered with smear layer.Highest bond strength was shown by laser prepared acid etched group, followed by bur prepared the acid etched group. The bur prepared nonacid etched group showed least bond strength.

Conclusions:

Er, Cr: YSGG laser can be used for preparing tooth and bond strength value achieved by laser preparation alone without surface treatment procedure lies in the range of clinical acceptability.Key Words: Acid etching, bond strength, erbium, chromium: Yttrium, scandium, gallium, garnet laser, laser etching, scanning electron microscope     

Er,Cr:YSGG laser pretreatment of primary teeth for bonded fissure sealant application: a quantitative microleakage study

PURPOSE: Laser pretreatment of dental hard tissues prior to preventive or restorative procedures has been a subject of research. Unground primary enamel bears a prismless superficial layer which is known to be acid resistant. This in vitro study was conducted in order to evaluate the potential use of Er,Cr:YSGG laser in the pretreatment of occlusal surfaces of primary teeth prior to bonded fissure sealant application. MATERIALS AND METHODS: Occlusal surfaces of human primary mandibular molars were used (n =140). After pretreatment with Er,Cr:YSGG laser (group A) or not (group B), occlusal fissures were treated with one of the following in each of 7 subgroups (n = 10): 1. phosphoric acid-etch only; 2. Clearfil SE Bond; 3. FL Bond; 4. Adper Prompt L-Pop; 5. NRC+Prime & Bond NT; 6. One-Up Bond F; 7. Xeno III. All teeth were sealed with Fissurit F. The specimens were thermocycled (1000 times) and stored thereafter in distilled water at 37 degrees C for 8 months. Following immersion in 0.5% basic fuchsin solution, three bucco-lingual sections were made from each tooth. They were digitally photographed and the extent of dye penetration along the enamel-sealant interface was measured (in mm) with image analysis software. RESULTS: There was no difference between the Er,Cr:YSGG laser pretreated group (group A) and the nonlased grou (group B) (p > 0.05). The lowest microleakage values were observed in subgroups A1 and B1. Within the laser pretreated group, subgroups A1, A4, and A5 showed lower microleakage scores when compared to subgroups A2, A3, A6, and A7 (p < 0.05). As for the nonlased group, subgroups B1, B3, B4, and B5 demonstrated significantly lower microleakage scores than subgroups B2, B6, and B7 (p < 0.05). CONCLUSION: Er,Cr:YSGG laser pretreatment was not found to influence the resistance to microleakage of bonded fissure sealant application in primary teeth.     

两种不同牙体预备方法对前牙瓷贴面粘接效果的临床对比研究

目的：对46例242颗牙瓷贴面的临床观察,比较Er,Cr：YSGG激光和金刚砂车针进行前牙预备及瓷贴面的粘接效果。方法：选择242颗需要美容修复的前牙,使用Er,Cr：YSGG激光或金刚砂车针分别进行牙体预备,进行IPS Empress铸瓷贴面修复,每半年进行复查,对修复体密合性、脱落率和破损率进行评价。结果：经过2年的复查,经Er,Cr：YSGG激光进行牙体预备的贴面,其脱落率绝大多数低于4％;金刚砂车针进行牙体预备的贴面,其脱落率绝大多数高于4％。二者的边缘封闭性和破损率大致相同。结论：在前牙区瓷贴面修复中,Er,Cr：YSGG激光进行牙体预备能够获得较为理想的粘接效果。