不同的(牙合)向会聚度对Finesse全瓷冠的适合性影响的研究

目的:评估不同的(牙合)向会聚度对Finesse全瓷冠适合性的影响,为临床应用提供理论依据.方法:在(牙合)向会聚度分别为5°、10°、15°的超硬人造石代型上分别制作全瓷冠各10个,粘结(玻璃离子 3.5kg静止固位力)、包埋、片切.以体式显微镜测量边缘适合性AMO,边缘浮升量PMO,轴壁适合性AWA,(牙合)面适合性OA,通过单因素方差和q检验,进行统计分析.结果:各组的边缘适合性均在临床要求范围内.5°组、10°组、15°组的AMO分别为109μm滋m、66μm滋m、69μm滋m;5°组与10°组、15°组的AMO,PMO,OA相比较时存在显著性差异(P《0.05),10°组与15°组无显著性差异(P》0.05).结论:Finesse热压铸型陶瓷冠具有良好的适合性,能满足临床应用要求.为保证较高的适合性,临床应采用10°到15°的牙体预备.     

不同制作方法对Finesse全瓷冠的适合性影响的研究

目的:评估不同的制作方法对F inesse全瓷冠的适合性的影响,为临床应用提供理论依据。方法:分别用3种方法即常规脱模法,带模铸造法,代型隙料法制作全瓷冠,粘结(玻璃离子3.5 kg静止固位力),包埋,片切。测量边缘适合性AMO,边缘浮升量PMO,轴壁适合性AWA,牙合面适合性OA,通过单因素方差和q检验,统计分析。结果:带模组、代型组、脱模组的AMO分别为53μm、66μm、120μm,脱模组与带模组,代型组相比较AMO、PMO、OA均有显著性差异(P<0.05),带模组,代型组的AMO、PMO、OA相比较时无显著性差异P>0.05。结论:F inesse热压铸型陶瓷冠具有良好的适合性,能满足临床应用要求,为保证较高的适合性,临床应用隙料法和带模铸造法来制作F inesse全瓷冠。     

不同轴面聚合度对cercon全瓷冠边缘适合性的影响研究

目的：研究不同聚合度牙体设计对cercon全瓷冠边缘适合性的影响。方法：以上颌第一磨牙为实验对象,于牙体釉牙骨质界下2mm处做标记后完全埋入自凝塑料中。将离体牙模型在牙科研磨仪上分别制备成轴面聚合度为4。、8。、12。,用肩台车针预备成90。肩台,宽约1rflm,骀面为120。～140。。硅橡胶取离体牙印模,翻制树脂代型：（日本日进齿科材料有限公司）15个,颈缘打磨光滑,分成3组,每组各5个,分别是牙体聚合度4。（4。组）,牙体聚合度8。（8。组）,牙体聚合度12。（12。组）。冠粘结后于体视显微镜下（’总放大倍数为30）观测并记录冠的边缘间隙。结果：4。Cercon全瓷组的边缘平均间隙为（33．70士5．53）弘m,8。Cercon全瓷组的边缘平均间隙为（28．90土9．55）应m,12。Cercon全瓷组的边缘平均间隙为（27．40士4．19）肚m。各组间的边缘适合性存在显著差异（P〈O．01）。组间两两比较采用简单相关t_检验分析,4。组与8。组间存在显著差异（P〈O．05）,4。组与12。组间也存在显著差异（P〈O．01）,而8。组与12。组之间没有显著差异。所有全瓷冠的边缘间隙均〈100／zm。组间两两比较采用简单相关t一检验分析,4。,8。,12。组间P〈O．01,有显著差异,8。与12。组间,P〉O．05无显著性差异。结论：随着牙体轴壁聚合度的增大Cercon全瓷组的边缘间隙越小即边缘适合性越好,但聚合度从8。增大到12。全瓷冠的边缘适合性改善不明显。在本实验的研究范围内可以认为8。聚合度可以提供Cercon全瓷组较好的边缘适合性。     

粘接对全瓷冠边缘适合性影响的研究进展

近年来,随着陶瓷材料的技术革新及人们对美观要求的日益增高,全瓷冠的临床应用逐渐增多.良好的边缘适合性是全瓷冠获得临床成功的一项重要指标.粘接剂作为全瓷冠修复体与牙预备体之间的介质,是影响边缘适合性的重要因素.在全瓷材料不断研究与开发的同时,粘接对全瓷冠边缘适合性的影响也成为学者们关注的问题.本文就粘接对全瓷冠边缘适合性影响的研究进展作一综述.     

GI—I型粉浆涂塑铝瓷核冠适合性研究

用ＳＭＩ体视显微镜和片切测量法测定了ＧＩ－Ｉ型粉浆涂塑铝瓷核冠粘固前的边缘浮出量，粘固后的粘固剂厚度以及代型隙料的厚度。结果表明：粘固前的边缘浮出量迷２０．３８μｍ；粘固后的核冠整体的粘固剂厚度为３９．６６μｍ；采用代型隙料技术，涂刷两层隙料，可获得良好的边缘适合性。     

全瓷冠边缘适合性研究进展

目的全瓷修复体以其良好的美学效果而在临床上广泛应用,其修复体边缘适合性是评价全瓷冠成功的一个重要指标。本文从研究方法、黏结因素、牙体预备及加工工艺等临床角度对全瓷冠边缘适合性的影响因素作一综述。     

全瓷冠预备体聚合度对全瓷冠边缘适合性及抗压强度的影响

目的:探讨牙体预备设计对IPSEmpress2全瓷冠边缘适合性及抗压强度的影响。方法:制作三组聚合角度(4°、8°、12°)的复合树脂牙体代型,每组8个;在牙体代型上分别制作IPSEmpress2全瓷冠;粘结后采用体视显微镜测量冠的边缘适合性;然后使用万用测力机测试其抗压强度。结果:4°、8°、12°三组聚合度的全瓷冠边缘间隙均值分别为75.2μm、61.1μm、57.2μm,4°组与8°组间及4°组与12°组间均存在显著差异(P<0.05);而8°组与12°组间无显著差异(P>0.05)。4°、8°、12°三组聚合度的全瓷冠抗压强度均值分别为1879.9N、2097.3N、2091.7N,各组间抗压强度差异无显著性(P>0.05)。结论:聚合度从4°增大到8°时,IPSEmpress2全瓷冠的边缘间隙减小即边缘适合性越好,但聚合度从8°增大到12°边缘适合性改善不明显。牙体轴壁聚合度的增大并不能显著提高采用粘结系统粘结的全瓷冠的抗压强度。     

不同数字印模方式影响全瓷冠边缘适合性的研究

目的 研究硅橡胶印模扫描、直接光学印模和传统的物理印模对计算机义齿辅助设计与制作全瓷冠边缘适合性的影响。方法 用数控车床制备聚甲基丙烯酸甲酯材质下颌第一磨牙标准全冠预备体16个,采用硅橡胶制取精细印模,超硬石膏灌注翻制成石膏模型。分别采用扫描全冠预备体、硅橡胶印模和石膏模型获取数字化模型,制作48个氧化锆全瓷冠。采用间隙印模测量法评价3组冠的边缘间隙,应用SPSS 17.0软件对实验数据进行统计分析。结果 直接扫描组、硅橡胶印模组、超硬石膏组的全瓷冠边缘间隙测量结果分别为（69.18±9.47）、（81.04±10.88）、（84.42±9.96） μm。直接扫描组与硅橡胶印模组、超硬石膏组差异有统计学意义（P<0.05）,硅橡胶印模组与超硬石膏组之间差异无统计学意义（P>0.05）。结论 直接扫描、硅橡胶印模扫描、石膏模型扫描法全瓷冠的边缘适合性均在临床可接受范围之内,硅橡胶印模扫描可作为临床上获取数字模型的方式之一。     

GI-Ⅰ型粉浆涂塑铝瓷核冠适合性研究

用SMI体视显微镜和片切测量法测定了GI-I型粉浆涂塑铝瓷核冠粘固前的边缘浮出量、粘固后的粘固剂厚度以及代型隙料的厚度.结果表明:粘固前的边缘浮出量为20.38μm;粘固后的核冠整体的粘固剂厚度为39.66μm;采用代型隙料技术,涂刷两层隙料(Vita-Pt interspace vanish,厚度47.33μm),可获得良好的边缘适合性.     

不同光学印模法对全瓷冠边缘和内部适合性影响的实验研究

目的研究Cerec 3D/Inlab MC XL系统不同光学印模法对Cerec Blocs全瓷冠边缘和内部适合性的影响。方法制备1个右侧下颌第一磨牙全冠预备体模型,复制32个石膏代型。采用随机抽样法,16个代型用于冠粘接,16个代型用于光学印模采集,其中直接法和间接法各选取8个,分别制作8个Cerec Blocs全瓷冠。采用修正美国公共卫生服务（USPHS）标准和扫描电镜（SEM）法评价冠的适合性,SAS 9.1软件对实验数据进行统计分析。结果修正USPHS法显示87.5%的边缘测试点临床可接受,直接法与间接法边缘适合性比较差异无统计学意义（P>0.05）;SEM法显示所有冠的边缘测试点均小于120 μm,直接法与间接法边缘和内部适合性比较差异均无统计学意义（P>0.05）,但直接法在近中、颊面、舌面、面的适合性优于间接法（P<0.05）;直接法远中轴面适合性较差,与近中轴面比较差异有统计学意义（P<0.01）。结论光学印模法对Cerec Blocs冠边缘适合性无影响,但对内部适合性有一定影响,全瓷冠边缘适合性均在临床可接受范围内。     

GI-Ⅱ型渗透陶瓷底层冠适合性及轴面聚合度对适合性的影响研究

目的　研究GI-Ⅱ型渗透陶瓷底层冠的适合性以及牙体预备时轴面聚合度对适合性的影响。方法分别为 1 5个具有三种不同聚合度 (5 、1 0 、1 5 )的上前磨牙制备GI -Ⅱ型渗透陶瓷底层冠 ,粘结后测定底冠适合性。结果　 5 、1 0 、1 5 聚合度牙体预备底层冠绝对边缘间隙量分别为 1 0 5μm、66 .2 0 μm、69.37μm。聚合度从 5 增加到 1 0 时适合性显著提高 ,1 0 以上则提高不显著。结论　GI -Ⅱ型渗透陶瓷底层冠具有良好的适合性 ,牙体预备时聚合度对GI -Ⅱ型渗透陶瓷底层冠适合性有显著影响     

基牙不同轴面聚合度对GI-Ⅱ全瓷冠抗碎裂载荷影响的研究

目的：研究3种不同的牙体轴面聚合度（5°,10°,15°）对GI-Ⅱ全瓷冠抗碎裂载荷的影响,为临床全瓷冠基牙预备找到较合适的轴面控制角度提供参考依据。方法：制备3组离体牙的轴面聚合度分别为5°,10°,15°,在其上制作GI-Ⅱ全瓷冠,固定形成试件后加压直至冠碎裂,采集数据后进行单因素方差分析。结果：5°与10°的轴面聚合度对GI-Ⅱ全瓷冠的抗碎裂载荷的影响无差别（P〉0.05）;而15°组与5°、10°组相比较则有显著性差异（P〈0.05）。结论：超过一定范围的轴面聚合度对GI-Ⅱ全瓷冠的抗碎裂载荷能力是有影响的。     

Marginal adaptation of all-ceramic crowns on implant abutments

Background: Studies focusing on the marginal accuracy of all‐ceramic crowns on implant abutments are in short supply. Purpose: This study evaluated the marginal accuracy of all‐ceramic crowns on different implant abutments. Materials and Methods: Ninety‐six standardized maxillary central incisor crowns (48 alumina and 48 zirconia) were fabricated for each of the six test groups (n = 16) (Ti1, titanium abutments–alumina crowns; Ti2, titanium abutments–zirconia crowns; Al1, alumina abutments–alumina crowns; Al2, alumina abutments–zirconia crowns; Zr1, zirconia abutments–alumina crowns; Zr2, zirconia abutments–zirconia crowns). The crowns were adhesively luted using a resin luting agent. The marginal gaps were examined on epoxy replicas before and after luting as well as after masticatory simulation at 200× magnification. Results: The geometrical mean (95% confidence limits) marginal gap values before cementation, after cementation, and after masticatory simulation were group Ti1: 39(37–42), 57(53–62), and 49(46–53); group Ti2: 43(40–47), 71(67–76), and 64(59–69); group Al1: 57(54–61), 87(85–90), and 67(65–69); group Al2: 66(63–69), 96(90–101), and 75(72–78); group Zr1: 54(51–57), 79(76–82), and 65(63–67); and group Zr2: 64(60–68), 85(80–91), and 75(70–81). The comparison between non‐cemented and cemented stages in each group demonstrated a significant increase in the marginal gap values after cementation in all groups (p < .001), while the comparison between cemented and aged stages in each group showed a significant decrease in the marginal gap values in groups Al1, Al2, and Zr1 (p < .0001). This reduction was not significant for groups Ti1, Ti2, and Zr2 (p > .05). Conclusion: The marginal accuracy of all tested restorations meets the requirements for clinical acceptance.     

Influence of different convergence angles and tooth preparation heights on the internal adaptation of Cerec crowns

STATEMENT OF PROBLEM: Because of an imagining principle called active triangulation in the Cerec system, a shadow is cast distal to the illuminated objects. This distal shadow may be enlarged when the occlusal-cervical height of the prepared tooth is increased. Depth data of the shadow are unreliable, so the internal fit of Cerec crowns has been questioned. PURPOSE: This study evaluated the influence of different convergence angles and tooth preparation heights on the internal adaptation of Cerec crowns. MATERIAL AND METHODS: Tooth preparations were made on typodont teeth with different combinations of convergence angles and occlusal-cervical heights: Group I = 20 degrees angle, 6 mm height; Group II = 20 degrees angle, 4 mm height; Group III = 12 degrees angle, 6 mm height; and Group IV = 12 degrees angle, 4 mm height. Ten Cerec crowns were fabricated for each type of tooth preparation. Measurements of the internal fit were performed with the cement space replica technique and an image analysis system. Three-way analysis of variance was used to analyze the differences in cement space with different tooth preparations and the number of times that milling tools were used to prepare the Cerec crowns (P<.05). Multiple comparisons were made to evaluate differences between groups (P<.0083). RESULTS: Cerec crowns with a 12 degrees convergence angle demonstrated the best internal fit (cement space in Groups III and IV = 121 +/- 41 microm and 115 +/- 42 microm, respectively). The difference between the 2 convergence types was within the range of the scanning error (25 microm) produced by the Cerec camera. The number of times that milling tools were used had no significant effect on internal fit (P=.78). Tooth preparation height equal to or shorter than 6 mm occlusal-cervically with both 12 degrees and 20 degrees convergence angles also had no significant effect on internal fit (P>.0083). Cement space at distal walls (185 +/- 28 microm) was the thickest among all axial walls (P=.0001) and was twice as thick as that at the facial (90 +/- 14 microm) and palatal walls (92 +/- 15 microm). CONCLUSION: Within the limitations of this study, there was little difference in the internal fit of Cerec crowns prepared with convergence angles of 12 degrees and 20 degrees. Distal shadows influenced the thickness of the cement spaces, particularly at the distal walls. However, tooth preparations with an occlusal-cervical height not greater than 6 mm did not exaggerate the effect of the distal shadows.     

Measuring abutment convergence angles using stereovision dental image processing system

PURPOSE

The purpose of this study was to develop a dental image processing system using a three-dimensional (3D) camera and stereovision technology. The reliability of the system for measuring axial wall convergence angles was evaluated.

MATERIALS AND METHODS

The new system predicted 3D coordinate points from 2D images and calculated distances and angles between points. Two examiners measured axial wall convergence angles for seven artificial abutments using a traditional tracing-based method (TBM) and the stereovision-based method (SVBM). Five wax abutment models of simplified abutment forms were made and axial wall convergence angles of wax models were measured by both methods. The data were statistically analyzed at the level of significance, 0.05.

RESULTS

Intraclass correlation coefficients showed excellent intra-examiner and inter-examiner reliabilities for both methods. Bland-Altman plots and paired t-tests showed significant differences between measurements and true values using TBM; differences were not significant with SVBM.

CONCLUSION

This study found that the SVBM reflected true angle values more accurately than a TMB and illustrated an example of 3D computer science applied to clinical dentistry.     

Influence of abutment substrate and ceramic thickness on the colour of heat-pressed ceramic crowns

All-ceramic crowns made of leucite-based heat-pressed ceramics are widely used to restore non-vital teeth in conjunction with various post and core materials. However, as some light passes through the ceramic, the colour of the abutment substrate can negatively affect the final aesthetic appearance of the all-ceramic crown. In this study, we made background specimens simulating gold-alloy cast posts and other simulating porcelain veneered cast posts, overlaid different thickness of heat-pressed ceramic on these background specimens, and measured the shifts in colour. We found that, when the background specimen was a gold alloy, the background colour had an effect on the apparent colour, unless the ceramic was more than 1.6 mm thick. When the background specimen was porcelain veneered, the background colour had no evident effect, even when the ceramic was not very thick. Therefore, when making a restoration using a leucite-based heat-pressed ceramic crown, it is advisable to use tooth-coloured materials such as a porcelain veneered cast post, if you will not be able to make the ceramic more than 1.6 mm thick.     

固定义齿基牙聚合角的测量与讨论

目的测量对比不同牙位、不同设计时基牙聚合角的值。方法测量226个不同牙位,不同设计基牙的近远中径与颊舌径,利用上下之差计算出聚合角。在测量的每个面上选取三点,即龈端点、中点、切端点。用游标卡尺测量两相对面上对应点间的距离,分别纪录各组数据,再计算上,下半端的值。结果各牙位的聚合角的平均值为第一前磨牙4.13°±0.77°,第二前磨牙4.14°±0.76°,第一磨牙4.46°±0.95°,第二磨牙4.76°±0.84°。前磨牙与磨牙之间的聚合角有显著性差别,但第一前磨牙与第二前磨牙之间、第一磨牙与第二磨牙之间无显著差别。第一磨牙为基牙的单冠、三单位桥、长桥的聚合角的平均值分别为3.78°±0.74°、4.69°±0.75°、5.08°±0.85°,单冠与三单位桥、长桥之间均有差别。而三单位桥、长桥间无差别。结论不同牙位,不同设计对聚合角有影响。对于不同的牙位及设计,要视临床的具体情况调整聚合角大小,不能都在2°～5°之间。     

O型圈附着体内冠聚合度改变对固位力的影响

目的　研究O型圈附着体内冠聚合度的改变对修复体固位力的影响。方法　采用机械加工方法制作O型圈附着体内冠替代物 ,分为 6 、9 、12 和 15 四组。应用O型圈后 ,铸造法制作外冠 ,通过拉力传感器测定外冠脱位力 ,该传感器与应变仪和微机相连。在微机中编制程序软件 ,可以记录外冠脱位时的瞬间峰值。结果　内、外冠脱位时 ,脱位力大小与内冠聚合度关系密切。内冠角度相同时 ,使用O型圈的脱位力明显大于不用O型圈 (P <0 .0 1)。不使用O型圈 ,当内冠聚合度大于 9 时 ,固位力明显下降。使用O型圈脱位力随内冠聚合度的增加而下降 ;当内冠聚合度为 15 时 ,其脱位力与不用O型圈内冠聚合度 6 时相当。结论　使用O型圈可以明显提高修复体固位力。使用O型圈内冠聚合度在 15 时 ,与不用O型圈内冠聚合度 6 时的固位力相当 ,提示O型圈式附着体内冠聚合度 15 以内时可满足修复固位要求