型盒石膏型腔表面上分离剂涂不上去的处理方法

当型盒浸泡在热水中时间过长，打开型盒，内部的蜡型已溶化成液体。同时烫溶的蜡液已浸入石膏中。如在涂分离剂前不采取补救措施，分离剂很难均匀涂在石膏型腔表面上，由于分离剂涂的不好，填塞塑料后石膏吸收了塑料单体，致使热处理后的义齿在基托组织面粘着很多石膏，而...     

全口义齿按原形快速翻制法

一、复制工作模型:将原全口义齿取下洗净、擦干,于基托组织面内外用毛笔均匀涂一薄层不含气泡之分离剂,且灌注石膏模型。在石膏尚未硬固前,将义齿及模型以调拌石膏一并装入中型盒底层,要求基托非组织面暴露于石膏外。二、制作弹性膏全口义齿阴模;于底层型盒石膏及义齿基托、牙冠表面用毛笔均匀涂一薄层液状石腊。将调拌好尚有流动性的部分弹性膏用震颤法逐渐快速复盖义齿牙冠及基托,防止产生空     

应用常用架作全口义齿自凝塑料口外垫底的体会

操作程序一、取模:取模前将上下颌义齿基托组织面磨粗糙,调拌流动性较好的弹性印模料,放入义齿基托组织面,戴入患者口内,嘱患者作正中咬(牙合),印模料凝固后从口内取出义齿,用盐水灌模型.二、上(牙合)架:石膏模凝固后.将上下颌义齿对正咬(牙合),上(牙合)架.三、填胶:(牙合)架上的石膏凝固后,将上下颌义齿取下,去除印模料.模型的组织面涂分离剂.在上下颌义齿基托的组织面涂布调好的自凝塑胶,放     

全口义齿的基托成型

全口义齿基托成型关系到义齿基托加工精度。基托成型传统采用装盒法,通过装盒、烫盒、冲蜡、充填树脂、压盒、热处理、出盒、磨光等步骤将义齿基托蜡型替换成树脂基托。注塑法是另外一种义齿基托成型技术,制作过程简便,加工精度更高,并且能够保存无牙颌石膏模型,但是需要特殊设备。本文详细描述了上述2种临床基托成型技术,并且比较了两者的优缺点。     

基托折裂简易固定法

将拆断的基托按原位对合好后用手压紧,然后将雕刻刀的尖头在酒精灯上烧红后,立即在断裂处烫烧,可每隔1.5cm烫一处,基其余的断裂处可用熔化的蜡覆盖,烫热处的塑料会将基托牢牢地粘到一块,最后在基托的组织面填放石膏,待石膏凝固后,将折裂处表面的蜡制除即可打磨固定。     

塑料热处理方法对义齿基托组织面粗糙度 的影响

据文献报道,有25％～74％的义齿基托组织面粗糙与质量不好,对义齿床粘膜有损害作用。作者研究热处理方法对于塑料表面质量的影响,共检查32个塑料标本。实验方法:用同一的石膏在相同条件下调拌制成石膏模型,用基托蜡片制作32个蜡型标本,30×50×3mm大小。分两组,第1组在前一天装盒,去蜡以后,放在干燥箱内,升温到60℃保持12小时     

介绍一种用热钢丝固定折断基托的方法

在修理义齿基托折断时,常规用细签或火柴棍加蜡固定进行修理。经临床应用,我们认为这种修理方法存在着一定的不足:(1)用蜡固定折断之基托,固定不牢固,不能当即在患者口内试戴;(2)蜡固定灌注石膏后,因石膏具有一定的膨胀性,常使折断处出现裂缝,使义齿产生一定的变形     

锡锑合金修复缺失牙间隙过小

我们用锡锑合金代替塑料,修复缺失的牙齿,效果较好。适用于一个双尖牙或一个磨牙缺失,而缺隙变小,但能容纳卡环的体部。重度磨耗牙冠变短,不愿意接受固定义齿修复所致的去髓术者。作法:基牙预备与制取印模同可摘义齿。在石膏代型缺隙龈向处均匀刮除1mm厚度,涂分离剂。常法设计与弯制卡环,用蜡在缺隙处将卡环体部固定在代型上,缺隙处用蜡根据咬合情况雕出蜡牙;牙槽嵴有吸收者,应基托与蜡牙一同雕出,以便整体铸造。在蜡牙的颊或舌侧面作铸道针。常法包埋,去蜡。     

不同聚合方法对基托树脂挠曲强度影响的实验研究

目的在实验室条件下比较2种义齿基托树脂经过4种聚合方法处理后基托树脂的挠曲强度,为临床选择适宜的聚合方法提供依据。方法用金属模具制备相同尺寸的蜡型96个,失蜡后使用2种品牌的义齿基托树脂填胶,用4种方法进行热处理使其固化,用万能力学实验机检测基托树脂的挠曲强度．用双因素方差分析和多重比较进行统计学处理。结果两种基托树脂的挠曲强度具有显著差异（P〈0.01）,不同聚合方法间基托树脂的挠曲强度除电热法与一组水浴方法存在显著差异外．其余组间无显著差异。结论基托树脂的挠曲强度和材料的性能有关,不同聚合方法对基托树脂的挠曲强度没有显著影响。     

全口义齿基托的临床检查和调改

全口义齿初戴应该包括一套完整的对义齿基托检查、调改的临床操作步骤,其目的是保证义齿基托与患者口腔组织良好适合。义齿基托检查需要非常仔细并且准确,可以通过以下材料和方法按顺序进行:基托边缘通过边缘指示蜡进行;基托组织面采用压力指示剂检查;基托磨光面也可以通过压力指示剂检查患者发音情况来调改。本文通过临床图片详细介绍了全口义齿基托在临床初戴与调改的整个过程。     

应用激光扫描法测量激光快速成形技术制作全口义齿钛基托的适合性研究

目的:评价新型激光快速成形方法制作全口义齿钛基托的适合性.方法:应用激光快速成形技术制作标准上半口无牙颌钛基托,将制作的基托置于无牙颌模型上,蜡封闭边缘后,装盒;待石膏凝固后,取出无牙颌模型,再次在型盒内灌制超硬石膏模型.待模型结固后,将两个模型分别置于LSH600三维激光扫描仪工作台上的同一位置并固定,利用三维激光扫...     

不同磨光方法对弹性义齿基托表面粗糙度影响的实验研究

目的:研究不同磨光处理对弹性义齿基托表面粗糙度的影响,为临床选择合适的磨光方法提供参考。方法:常规制作弹性基托试件90个,随机分为3组,分别采用硅橡胶磨头(1#-3#),金刚砂磨头(001#、002#),砂纸卷(500目、1000目、1500目)粗磨,采用布轮沾水,布轮沾抛光蜡,布轮沾抛光蜡和亮托抛光浆细磨抛光,利用表面粗糙度检查仪测定其粗糙度,扫描电镜观察磨光后的表面形貌,然后对检测结果进行统计学分析。结果:表面粗糙度检查仪检测:不同粗磨方法样本组的表面粗糙度(Ra值)的平均值比较:砂纸组<硅橡胶磨头组<金刚砂组,统计学上存在显著性差异(P<0.001);各组抛光方法表面粗糙度(Ra值)的平均值比较:布轮沾抛光膏和亮托抛光浆组<布轮沾抛光膏组<布轮沾水组,统计学上存在显著性差异(P<0.001)。扫描电镜观察:经金刚砂粗磨,试件表面粗糙,划痕较多,较深;经硅橡胶磨头粗磨,试件表面较光滑,划痕较浅;经1500目砂纸粗磨,试件表面最光滑,划痕最浅。经布轮沾水抛光,试件表面粗糙,划痕较多,较深;经布轮沾抛光蜡抛光,试件表面较光滑,划痕较浅;经布轮沾抛光蜡和亮托抛光浆抛光,试件表面最平滑。结论:经砂纸;硅橡胶磨头;金刚砂处理弹性义齿试件,获得不同的表面粗糙度,经1500目砂纸和硅橡胶磨头处理的试件表面平滑。经布轮沾抛光蜡,布轮沾亮托抛光浆抛光弹性义齿试件表面,表面粗糙度得到显著降低,试件表面平滑。弹性义齿试件不同的粗磨和抛光方法之间存在交互作用,经1500目砂纸粗磨和布轮沾抛光蜡和亮托抛光浆处理后,可以获得较低的粗糙度值,试件表面最平滑。     

Comparison of the Dimensional Accuracy of Injection-Molded Denture Base Materials to that of Conventional Pressure-Pack Acrylic Resin

Purpose : This study compared the linear dimensional changes of 3 injection-molded denture base materials to that of conventionally processed polymethylmethacrylate (PMMA) resin.
Materials and Methods : An impression of an aluminum maxillary edentulous arch was made with a condensation silicone impression material (Denture Elasticon) to fabricate a gypsum master cast that was replicated as a silicone mold. A maxillary complete denture with acrylic teeth was waxed to full contour on the master cast and replicated to make 40 wax dentures. ERA attachments cast in metal (Rexillium) with indices milled into the centers were waxed into 3 positions in each denture for recording dimensional measurements of the wax denture. Ten dentures were allocated to each of 4 groups; Group 1 was processed using conventionally processed PMMA (Microlon), Group 2 used injection-molded PMMA (SR-lvocap), Group 3 employed injection-molded nylon (Valplast), and Group 4 used injection-molded styrene (Northern). All processed specimens were stored at room temperature (25°C, ambient humidity) for 1 week (while still on the master cast) before anteroposterior and cross-arch measurements were made using the ERA reference points with a digital caliper. After separation from the master cast and following water storage at 37°C for 7 days additional measurements were made.
Results : An analysis of the results showed that the effect of processing was not the same for the 3 dimensions studied, regardless of which dimension was considered ( p < 0.0001). The pattern of dimensional changes associated with the material type was not the same between the wax and processing stages as it was for the change between the processing and decasting stages ( p < 0.0001).
Conclusions : Processing the denture base materials produced unequal deformation in different dimensions (anterior-posterior and cross-arch). Each material tested also responded differently to the processing stages.     

丙酮及甲基丙烯酸甲酯表面处理对基托树脂与软衬材料粘接效果的影响

目的 研究丙酮及甲基丙烯酸甲酯表面处理对基托树脂与软衬材料间微渗漏、粘接强度及基托树脂抗弯强度的影响.方法 制备30 mm×30 mm×2 mm树脂块36块,根据随机数字表随机均分为3组,每组12块,丙酮组:树脂块粘接面浸泡于丙酮溶液中30 s;甲基丙烯酸甲酯组:树脂块粘接面浸泡于甲基丙烯酸甲酯溶液中180 s;对照组:不进行表面处理.两树脂块间衬以2 mm软衬材料后粘接,冷热循环5000次,浸泡于131Ⅰ溶液中24h后计数γ射线,即微渗漏数.制备36块30 mm×10 mm ×7.5 mm树脂块,分组及表面处理同上.两树脂块间衬以3 mm软衬材料后粘接,冷热循环5000次后,测试拉伸强度,即粘接强度.制备18块65 mm× 10 mm×3.3 mm树脂块,分组及表面处理同上,涂布软衬材料粘接剂后测试抗弯强度.结果 丙酮组和甲基丙烯酸甲酯组的微渗漏数(520.0±562.2和493.5±447.9)均小于对照组(1369.5±590.2,P＜0.05);丙酮组和甲基丙烯酸甲酯组粘接强度[(1.5±0.4)和(1.4±0.5) MPa]均大于对照组[(0.9±0.2) MPa,P＜0.05];两实验组间微渗漏数和粘接强度差异均无统计学意义(P＞0.05);3组抗弯强度差异均无统计学意义(P＞0.05).结论 丙酮及甲基丙烯酸甲酯表面处理可减少软衬材料与基托树脂间微渗漏,增加两者间粘接强度,未导致基托树脂抗弯强度下降.     

Cytotoxicity of denture base resins: effect of water bath and microwave postpolymerization heat treatments

PURPOSE: This study compared the effect of two postpolymerization heat treatments on the cytotoxicity of three denture base resins on L929 cells using 3H-thymidine incorporation and MTT assays. MATERIALS AND METHODS: Sample disks of Lucitone 550, QC 20, and Acron MC resins were fabricated under aseptic conditions and stored in distilled water at 37 degrees C for 48 hours. Specimens were then divided into three groups: (1) heat treated in microwave oven for 3 minutes at 500 W; (2) heat treated in water bath at 55 degrees C for 60 minutes; and (3) no heat treatment. Eluates were prepared by placing three disks into a sterile glass vial with 9 mL of Eagle's medium and incubating at 37 degrees C for 24 hours. The cytotoxic effect from the eluates was evaluated using the 3H-thymidine incorporation and MTT assays, which reflect DNA synthesis levels and cell metabolism, respectively. RESULTS: The components leached from the resins were cytotoxic to L929 cells when 3H-thymidine incorporation assay was employed. In contrast, eluates from all resins revealed noncytotoxic effects as measured by MTT assay. For both MTT assay and 3H-thymidine incorporation, the heat treatments did not decrease the cytotoxicity of the materials tested. CONCLUSION: Resins were graded by 3H-thymidine incorporation assay as slightly cytotoxic and by MTT assay as noncytotoxic. Cytotoxicity of the denture base materials was not influenced by microwave or water bath heat treatment.     

Effect of pre-processing surface treatments of acrylic teeth on bonding to the denture base

Summary  The aim of this study was to examine the bond strength between acrylic teeth after various surface treatments and processing with either a heat- or microwave-polymerized denture base material. Specimens were prepared and tested according to the methods described in American National Standard/American Dental Association Specification No.15 (Synthetic Polymer Teeth) using a special assembly. Three brands of acrylic teeth were used with the following treatments: control (no treatment), grinding and grinding plus sandblasting. Treatment groups were further divided into two denture base processing subgroups: heat-polymerized and microwave-polymerized methods. Denture base processing to the acrylic teeth was performed according to the manufacturer's recommendations. Bond strength test was performed using a universal testing machine with five specimens and each specimen is composed of six anterior teeth per experimental group. Data were analysed using a three-way anova and the Scheffe' F -test post hoc pair wise comparison at the 95% significance level. The mean bond strength values ranged from 33.1 ± 4.1 to 51.6 ± 2.5 MPa. The bond strength values of sandblasted surfaces were significantly higher than those of the ground surface and the control ( P  < 0.05). Combined (acrylic tooth and denture base resin) cohesive failures were disclosed in all tested samples. Acrylic tooth surface pre-processed surface treatment with grinding plus sandblasting and processed with a heat-polymerized denture base provided the greatest bond strength between acrylic tooth and denture base.     

The evaluation of microleakage and bond strength of a silicone-based resilient liner following denture base surface pretreatment

STATEMENT OF PROBLEM: The failure of adhesion between a silicone-based resilient liner and a denture base is a significant clinical problem. PURPOSE: The purpose of this study was to examine the effects of denture base resin surface pretreatments with different chemical etchants preceding the silicone-based resilient liner application on microleakage and bond strength. The initial effects of chemical etchants on the denture base resin in terms of microstructural changes and flexural strength were also examined. MATERIAL AND METHODS: Forty-two polymethyl methacrylate (PMMA) denture base resin (Meliodent) specimens consisting of 2 plates measuring 30 x 30 x 2 mm were prepared and divided into 7 groups (n = 6). Specimen groups were treated by immersion in acetone for 30 (A30) or 45 (A45) seconds, methyl methacrylate monomer for 180 (M180) seconds, and methylene chloride for 5 (MC5), 15 (MC15) or 30 (MC30) seconds. Group C had no surface treatment and served as the control. Subsequently, an adhesive (Mollosil) and a silicone-based resilient denture liner (Mollosil) were applied to the treated surfaces, and all specimens were immersed in the radiotracer solution (thalium-201 chloride) for 24 hours. Tracer activity (x-ray counts), as a parameter of microleakage, was measured using a gamma camera. For bond-strength measurement, 84 rectangular PMMA specimens (10 x 10 x 40 mm) were surface-smoothed for bonding and treated with the different chemical etchants using the same previously described group configurations. The adhesive and the silicone-based denture liner were applied to the treated surfaces. Tensile bond-strength (MPa) was measured in a universal testing machine. Flexural strength measurement was performed with 49 PMMA specimens (65 x 10 x 3.3 mm according to ISO standard 1567) in 7 groups (n = 7), with 1 flat surface of each treated with 1 of the chemical etchants preceding adhesive application. The flexural strength (MPa) was measured using a 3-point bending test in a universal testing machine. The data were analyzed by 1-way analysis of variance and the Tukey HSD test (alpha = .05). RESULTS: Significant differences were found between the groups in terms of microleakage (P < .0001). The lowest microleakage was observed in group M180 (30,000 x-ray counts) and the highest in the control group (44,000 x-ray counts). The mean bond strength to PMMA resin ranged from 1.44 to 2.22 MPa. All treated specimens showed significantly higher bond strength than controls (P < .01). The flexural strength values all significantly differed (P < .05). All experimental specimens that had chemical surface treatments showed lower flexural strength than controls (P < .05). CONCLUSION: Treating the denture base resin surface with chemical etchants increased the bond strength of silicone-based resilient denture liner to denture base and decreased the microleakage between the 2 materials. Considering the results of both tests together, the use of methyl methacrylate monomer for 180 seconds was found to be the most effective chemical treatment.     

EFFECT OF POST-POLYMERIZATION HEAT TREATMENTS ON THE CYTOTOXICITY OF TWO DENTURE BASE ACRYLIC RESINS

Introduction:

Most denture base acrylic resins have polymethylmethacrylate in their composition. Several authors have discussed the polymerization process involved in converting monomer into polymer because adequate polymerization is a crucial factor in optimizing the physical properties and biocompatibility of denture base acrylic resins. To ensure the safety of these materials, in vitro cytotoxicity assays have been developed as preliminary screening tests to evaluate material biocompatibility. ³H-thymidine incorporation test, which measures the number of cells synthesizing DNA, is one of the biological assays suggested for cytotoxicity testing. Aim: The purpose of this study was to investigate, using ³H-thymidine incorporation test, the effect of microwave and water-bath post-polymerization heat treatments on the cytotoxicity of two denture base acrylic resins.

Materials and Methods:

Nine disc-shaped specimens (10 x 1 mm) of each denture base resin (Lucitone 550 and QC 20) were prepared according to the manufacturers'' recommendations and stored in distilled water at 37°C for 48 h. The specimens were assigned to 3 groups: 1) post-polymerization in a microwave oven for 3 min at 500 W; 2) post-polymerization in water-bath at 55° C for 60 min; and 3) without post-polymerization. For preparation of eluates, 3 discs were placed into a sterile glass vial with 9 mL of Eagle''s medium and incubated at 37°C for 24 h. The cytotoxic effect of the eluates was evaluated by ³H-thymidine incorporation.

Results:

The results showed that the components leached from the resins were cytotoxic to L929 cells, except for the specimens heat treated in water bath (p<0.05). Compared to the group with no heat treatment, water-bath decreased the cytotoxicity of the denture base acrylic resins.

Conclusion:

The in vitro cytotoxicity of the tested denture base materials was not influenced by microwave post-polymerization heat treatment.     

不同类型义齿清洁剂对着色热凝基托树脂和树脂人工牙的清洁效果

目的:比较不同类型义齿清洁剂对着色热凝基托树脂和树脂人工牙的清洁效果.方法:将40块规格相同的热凝基托树脂试件和40颗贺利氏树脂人工中切牙,浸泡于咖啡、绿茶和酱油的混合液中4周,各随机分为4组(n=10),按使用说明分别浸泡在Polident、Steradent清洁片配成的溶液、质量分数为0.5％次氯酸钠溶液和蒸馏水(对照组)中4h,使用色差仪和电子比色仪分别测量热凝基托树脂和树脂人工牙着色前后、清洁剂浸泡后的色度值,计算试件处理前后的色差(△E)并进行统计学分析.结果:在着色前后,4组热凝基托树脂和4组树脂人工牙△E无统计学差异(P＞0.05).在着色后与清洁后的△E值,0.5％次氯酸钠组＞ Polident组和Steradent组＞蒸馏水组(P＜0.05);Polident组与Steradent组之间无统计学差异(P＞0.05).在着色前与清洁后,蒸馏水组的△E大于其他3组(P＜0.05);其他3组之间无统计学差异.结论:0.5％次氯酸钠、Polident和Steradent对着色热凝基托树脂和树脂人工牙均有有效的清洁效果,其中0.5％次氯酸钠优于Polident和Steradent,Polident和Steradent效果相同.