In vitro comparison of marginal adaptation of various filling materials. I. Effect of the filling material on marginal adaptation

In a two-month in vitro experiment cervical marginal adaptation was examined in relation to the preparation, filling method and restorative material. Fifty Class II cavities were prepared in fifty extracted sound human premolar and molar teeth extending to the approximal cement-enamel junction. The cavities to receive composite restorations were bevelled at the vestibulo-occlusal and -approximal enamel margins, the other aspects of the cavity enamel and gingival margins at the cement-enamel junction being prepared conventionally. The cavities for amalgam were prepared and filled conventionally. The specimens were cycled in different buffer solutions and temperature, modelling possible variations in the oral environment and examined with SEM. The results were analysed using ANOVA. The best marginal adaptation among the composites was achieved with Charisma, Estilux Posterior, Durafil and Prisma AP. H at the bevelled enamel margins, the worst marginal fit was with Heliomolar and Polofil. It was concluded, that adhesive technique reduces, but does not eliminate marginal leakage.     

Vertical marginal discrepancy of ceramic copings with different ceramic materials, finish lines, and luting agents: an in vitro evaluation

STATEMENT OF PROBLEM: Prosthetic restorations that fit poorly may affect periodontal health and occlusion. Studies that have evaluated the accuracy of fit of ceramic restorations before and after cementation assessed primarily intracoronal restorations. PURPOSE: This in vitro study evaluated the effect of different finish lines, ceramic manufacturing techniques, and luting agents on the vertical discrepancy of ceramic copings. MATERIAL AND METHODS: Two stainless steel molars were prepared for complete crowns with 2 different finish lines (heavy chamfer and rounded shoulder); each molar was duplicated to fabricate 90 copings. A total of 180 copings generated 18 groups (n=10 for each finish line-coping material-luting agent combination). Luting agents tested included zinc phosphate, resin-modified glass ionomer (Fuji Plus), and resin composite cements (Panavia F). A metal frame was developed on which to screw the stainless steel model and a ceramic coping; the distance (microm) between 2 predetermined points was measured before and after cementation by a profile projector under a torquing force. A 4-way ANOVA with repeated measurements was performed to assess the influence of each factor in the vertical marginal discrepancy: 3 between-coping factors (finish line-coping material-luting agent) and 1 within-coping factor (before and after cementation) (alpha=.05). RESULTS: Procera copings presented the lowest mean values ( P <.05) of vertical marginal discrepancy before and after cementation (25/44 microm) when compared to Empress 2 (68/110 microm) and InCeram Alumina copings (57/117 microm), regardless of any combinations among all finish lines and luting agents tested. CONCLUSION: Considering each factor separately, the ceramic manufacturing technique appeared to be the most important factor tested for the definitive vertical discrepancy of all-ceramic copings, with lower mean values for Procera copings.     

不同材料嵌体修复离体乳磨牙后断裂载荷及边缘密合性研究

摘要：目的    评估不同材料嵌体修复离体乳磨牙的断裂载荷及边缘密合性。方法    收集2020年7月至2021年7月于第四军医大学口腔医院儿童口腔科新鲜拔除的牙冠完整且根吸收不超过2/3的下颌第二乳磨牙55颗,用丙烯酸树脂块制备成试件。随机选择10个试件作为对照组;其余试件完成Ⅱ类洞嵌体预备后随机分为3组（每组15个）,分别使用3种不同材料完成嵌体修复（A组：IPS e. max CAD;B组：Lava Ultimate;C组：BioPAEK）。检测各组修复后即刻断裂载荷、冷热循环后断裂载荷、冷热循环后边缘密合性,并进行比较分析。结果    修复后即刻4组试件断裂载荷分别为A组（1527 ± 21.06）N、B组（1616 ± 23.85）N、C组（1580 ± 19.63）N、对照组（1643 ± 19.60）N,其中A组和C组断裂载荷均明显小于对照组断裂载荷（P < 0.05）,B组断裂载荷与对照组断裂载荷差异无统计学意义（P > 0.05）,B组和C组断裂载荷均明显大于A组断裂载荷（P < 0.05）。冷热循环后4组试件断裂载荷分别为A组（1477 ± 29.44）N、B组（1567 ± 24.17）N、C组（1484 ± 23.33）N、对照组（1608 ± 26.45）N,其中B组断裂载荷明显高于A组和C组（P < 0.05）,与对照组差异无统计学意义（P > 0.05）。冷热循环后3组试件轴壁染料渗透深度：A组（0.20 ± 0.02）mm、B组（0.21 ± 0.01）mm、C组（0.20 ± 0.02）mm;龈壁染料渗透深度：A组（0.36 ± 0.01）mm、B组（0.37 ± 0.01）mm、C组（0.38 ± 0.02）mm。3组试件轴壁及龈壁染料渗透深度差异均无统计学意义（P > 0.05）。结论    本实验现有条件下,综合考虑断裂载荷及边缘密合性,Lava Ultimate较其他两种材料更适用于乳牙的嵌体修复。     

瓷修复技术的临床应用Ⅷ.瓷嵌体的临床应用

瓷嵌体是一种嵌入牙体内部以恢复缺损牙体形态和功能的瓷修复体.由于其具有极佳的生物相容性和美学效果、良好的耐腐蚀性和耐磨损性,以及边缘密合性高,邻面可高度抛光形成良好的邻接关系等优点,目前瓷嵌体的临床应用越来越广泛.     

Effect of light curing units on marginal adaptation and hardness of Class II composite resin restorations

AIMS: The aim of this study was to test the influence of different curing protocols on dentin marginal adaptation and the hardness of two composites. METHODS AND MATERIALS: Three light-curing-units (LCUs): Quartz-Tungsten-Halogen (QTH: 541 mW/cm2), Argon-Ion-Laser (AL: 277 mW/cm2), and Plasma-Arc-Curing (PAC: 1818 mW/cm2) and two composites FiltekZ250 (F) and Tetric Ceram HB (TC) were tested. Sixty standardized "vertical-slot-Class II-cavities" were prepared at the mesial surface of bovine incisors and divided into six groups (n=10). Composites were placed using the Single Bond adhesive system and cured in 2 mm increments according to the manufacturers' instructions. After polishing, epoxy replicas were processed for scanning electron microscopy (SEM) marginal adaptation analysis at 500x magnification. The specimens were then sectioned transversally to the dental long axis, embedded in polyester resin, then polished and submitted to the Knoop hardness test at gingival and occlusal portions of the restoration. Data were analyzed using two-way analysis of variance (ANOVA) and Tukey's test (p=0.05). RESULTS: The gap margins ranged between 4.3 to 5.8 microm, and no statistically significant differences were revealed in marginal adaptation for LCUs or for composites (p>0.05). Location influenced hardness (p=0.01). The occlusal portion presented significantly higher KHN than the gingival portion for all composite-LCU combinations. Regardless of the LCU used, TC produced statistically significant lower hardness values (ranging between 82.8 to 110.7 KHN) than F (ranging between 105.9 to 117.3 KHN). CONCLUSIONS: Hardness and gap formation were not dependent on the LCUs tested in this study. Different resin composite was found to be a significant factor with regards to hardness but not gap formation.     

不同粘接剂间隙对CAD/CAM嵌体边缘适应性的影响

目的 探讨不同粘接剂间隙对CAD/CAM嵌体氧化锆粘接强度的影响.方法 选取因正畸需要拔除的第一前磨牙30颗作为本研究对象,依照设置粘接剂间隙参数不同分为10μm(A组)、30μm(B组)、50μm(C组)制作嵌体;用轻体型硅橡胶复制边缘间隙,体视显微镜测量边缘间隙的厚度,使用SPSS13.0软件包对数据进行分析.结果 所有瓷嵌体均可顺利就位,测量数据均小于120μm,A组肩台间隙明显低于B组及C组(P<0.05),且B组轴面显著低于C组(P<0.05).结论 在粘接间隙设定为10~50μm时,CEREC制作瓷嵌体均可取得满意效果.     

Selective enamel etching: effect on marginal adaptation of self-etch LED-cured bond systems in aged Class I composite restorations

The aim of this study was to evaluate the influence of previous enamel etch and light emitting diode (LED) curing on gap formation of self-etch adhesive systems in Class I composite restorations after thermomechanical aging (TMA). Thus, on 192 human molars, a box-shaped Class I cavity was prepared maintaining enamel margins. Self-etch adhesives (Clearfil SE and Clearfil S3) were used to restore the preparation with a microhybrid composite. Before application of the adhesives, half of the teeth were enamel etched for 15 seconds with 37% phosphoric acid; the other half were not etched. For the photoactivation of the adhesives and composite, three light-curing units (LCUs) were used: one polywave (Ultra-Lume LED 5, UL) and two single-peak (FlashLite 1401, FL and Radii-cal, RD) LEDs. After this, epoxy resin replicas of the occlusal surface were made, and the specimens were submitted to TMA. New replicas were made from the aged specimens for marginal adaptation analysis by scanning electron microscopy. Data were submitted to Kruskal-Wallis and Wilcoxon tests (α=0.05). Before TMA, when enamel was etched before the application of S3, no gap formation was observed; however, there were gaps at the interface for the other tested conditions, with a statistical difference (p≤0.05). After TMA, the selective enamel etching previous to the S3 application, regardless of the LCU, promoted higher marginal adaptation compared to the other tested groups (p≤0.05). Prior to TMA, higher marginal integrity was observed, in comparison with specimens after TMA (p≤0.05). With regard to Clearfil SE and Clearfil Tri-S cured with FL, no differences of gap formation were found between before and after aging (5.3 ± 3.8 and 7.4 ± 7.5, respectively), especially when the Clearfil Tri-S was used in the conventional protocol. When cured with RD or UL and not etched, Clearfil Tri-S presented the higher gap formation. In conclusion, additional enamel etching promoted better marginal integrity for Clearfil Tri-S, showing it to be an efficient technique for Class I composite restorations. The two-step self-etch adhesive was not influenced by selective enamel etching or by the LED-curing unit.     

Evaluation of the marginal seal of CEREC 3D restorations using two different luting agents

This in vitro study used two resin cements to evaluate the microleakage of CEREC 3D restorations. An mesio-occluso-distal-lingual (MODL) onlay preparation was placed on an ivorine premolar tooth. Sixty elastomeric impressions of this preparation were used to fabricate resin dies. Imaging propellant was applied to the resin dies. Optical impressions were taken with the CEREC 3 and the CEREC 3D software and used to design and mill 60 onlays. The reliability coefficient was alpha = 0.76 with an examiner agreement rate of 96.4%. Restorations cemented with posterior composite demonstrated a mean microleakage value of 1.46 mm (SD+/- 1.64); by contrast, those restored with dual-cure cement reported a mean microleakage value of 0.21 mm (SD+/-0.57). The difference in microleakage was very highly significant (alpha = 0.001). Posterior composite CEREC 3D restorations cemented with the dual-cure cement showed significantly less microleakage compared to those cemented with posterior composite.     

不同粘固剂对 IPS-Empress 2后牙全瓷冠边缘适合性的影响

目的 :探讨不同粘固剂粘固的IPS Empress 2后牙全瓷冠的边缘适合性。方法 :采用印模复制和扫描电镜技术 ,测量磷酸锌粘固剂、PanaviaF树脂粘结系统和Dyracteompomer粘结剂粘固的IPS Empress 2后牙全瓷冠咀嚼模拟试验前后的边缘粘固剂厚度 ,并观察粘固剂表面状态。结果 :3种粘固剂粘固的全瓷冠边缘粘固剂厚度无显著性差异 (P >0 .0 5 ) ;磷酸锌粘固剂粘固的全瓷冠边缘粘固层有明显缺损 ,且咀嚼模拟试验后缺损增多 ,而另两种树脂类粘固剂未见明显缺损。结论 :PanaviaF树脂粘结系统和Dyractcompomer粘结剂粘固的IPS Empress 2后牙全瓷冠具有良好而稳定的边缘适合性     

Influence of solvent type in experimental dentin primer on the marginal adaptation of Class V restorations

OBJECTIVES: The purpose of this in vitro investigation was to evaluate the influence of the solvent type in two experimental dentin primers (ExP) on the handling sensitivity by determining the marginal adaptation of mixed Class V restorations. METHODS: Standardized cavities were prepared in 32 extracted human molars and randomly assigned to four test groups (n=8). After etching, a three-step adhesive was applied using two ExP which only differed in the type of solvent (acetone/water=ExP-A versus ethanol/water=ExP-E). For ExP-A, the drying procedure (blot-drying versus 2s air drying) prior to primer application was varied, whereas evaporation time (2-3s versus 10s) after primer application was varied for ExP-E. An adhesive was added prior to application of the filling material. Specimens were thermocycled (TC: 2500 cycles; 5-55 degrees C). The length of gap-free margin (LoGfM) was assessed by SEM using replica technique. Data were subjected to non-parametric statistics (p=0.05) as well as the Levene test (p=0.05). RESULTS: Blot-drying significantly increased the LoGfM after TC for ExP-A in dentin (p<0.05) but decreased LoGfM in enamel (p<0.05). Short evaporation (2-3s) of solvent reduced LoGfM when using ExP-E and led to a significant increase in variances (p<0.05). CONCLUSIONS: The use of three-step adhesives with ethanol/water-based solvent is recommended due to a lower technique sensitivity versus acetone/water-based systems. Also when using modern ethanol/water-based three-step adhesives, evaporation of primer solvent remains a critical step regarding the marginal quality of the restorations and consequently has to be carried out thoroughly.     

Effect of different luting procedures on the seating of ceramic inlays

This in vitro study evaluated the effect of different luting procedures on the proper seating of ceramic inlays and on the marginal seal through microleakage testing. Sixty mesial-, occlusal-, distal- (MOD) cavities were prepared in third molars, and distributed among four groups. In the control group 1, the cavity surface was treated with dentin and enamel bonding agents; ceramic inlays were placed into the cavity and light cured. In group 2, the dentin and enamel bonding agents were cured prior to the placing of the inlays, and following the insertion. In group 3, the inlays were luted without enamel bonding. In group 4, the inlays were cemented using a one-bottle bonding and two times light curing. The groups with only one time light curing at the end of the luting process exhibited the smallest luting space following cementation. The smallest dye penetration values were obtained for the two groups with separate light curing of the dentin bonding agent. Reducing the film thickness of polymerized dentin bonding agents, i.e. by changing the composition of the bonding agents, could facilitate proper seating of ceramic inlays together with a better marginal seal.     

Influence of restorative techniques on marginal adaptation and dye penetration around Class V restorations

The aim of this study was to observe the influence of restorative techniques on marginal adaptation and dye penetration around Class V restorations simulating abfraction lesions. Sixty mandibular premolars were divided into six groups (n = 10) using different restorative materials. Cavity preparation presented the gingival wall localized in dentin and the incisal wall in enamel. Replicas of abfraction lesions were obtained and viewed under a stereomicroscope for adaptation assessment. All teeth were subjected to thermocycling and mechanical load cycling and immersed in 0.5% methylene blue dye (pH 7.2) for four hours. The results were tabulated and submitted to Kruskal-Wallis tests, which were significant for the dentin margin with lower microleakage values for primer/Vitremer, followed by Clearfil SE Bond/Durafill VS and Clearfil SE Bond/Z100 in qualitative and quantitative methods (P < 0.05). The enamel margin had no significant difference for microleakage values for all groups. There was no statistically significant difference among the substrates for marginal adaptation. The Spearman coefficient illustrated a direct relation between enamel and dentin for microleakage evaluation (P < 0.0001). The data demonstrated no difference for marginal fit by chi-square test. It can be concluded that all groups had microleakage in different degrees, with the lowest values for resin-modified glass ionomer.     

Stress distributions in adhesively cemented ceramic and resin-composite Class II inlay restorations: a 3D-FEA study.

OBJECTIVES: The purpose of this study was to investigate the effect of differences in the resin-cement elastic modulus on stress-transmission to ceramic or resin-based composite inlay-restored Class II MOD cavities during vertical occlusal loading. METHODS: Three finite-element (FE) models of Class II MOD cavity restorations in an upper premolar were produced. Model A represented a glass-ceramic inlay in combination with an adhesive and a high Young's modulus resin-cement. Model B represented the same glass-ceramic inlay in combination with the same adhesive and a low Young's modulus resin-cement. Model C represented a heat-cured resin-composite inlay in combination with the same adhesive and the same low Young's modulus resin cement. Occlusal vertical loading of 400 N was simulated on the FE models of the restored teeth. Ansys FE software was used to compute the local von Mises stresses for each of the models and to compare the observed maximum intensities and distributions. Experimental validation of the FE models was conducted. RESULTS: Complex biomechanical behavior of the restored teeth became apparent, arising from the effects of the axial and lateral components of the constant occlusal vertical loading. In the ceramic-inlay models, the greatest von Mises stress was observed on the lateral walls, vestibular and lingual, of the cavity. Indirect resin-composite inlays performed better in terms of stress dissipation. Glass-ceramic inlays transferred stresses to the dental walls and, depending on its rigidity, to the resin-cement and the adhesive layers. For high cement layer modulus values, the ceramic restorations were not able to redistribute the stresses properly into the cavity. However, stress-redistribution did occur with the resin-composite inlays. SIGNIFICANCE: Application of low modulus luting and restorative materials do partially absorb deformations under loading and limit the stress intensity, transmitted to the remaining tooth structures.     

Microleakage and marginal adaptation of composite resin restorations.

It has been shown that the use of a sealant offers no advantage with respect to the retentive strength of a composite resin restoration. However, for the improvement of marginal seal and adaptation, the present findings indicate that enamel etching and the application of a sealant, in conjunction with use of a cavity geometry which reduces shrinkage strain, are absolute necessities.     

Tensile bond strength of two ceramic and three resin composite inlay materials placed using a resin luting agent.

The tensile bond strength of inlay materials to dentin was evaluated. Five materials, two direct resin composite inlay products, one hybrid resin composite, a preformed ceramic block, and a conventional porcelain material were bonded to bovine dentin and bonded together using a dual-polymerizing resin luting agent. Specimens were tested with and without thermocycling. Some bar-to-bar bonding groups fractured through the bar. Significantly higher (P < .05) bar-to-bar bonds were recorded than the bar-dentin bonds, irrespective of the inlay materials. VitaDur N showed the lowest bar-to-bar failure values (7.6 MPa) compared to the four other inlay materials (14.4 MPa to 22.2 MPa), but had the highest dentin bond strength (4.5 MPa). Unexpectedly, thermal loading increased the bond strength to bovine dentin, although this was only statistically significant for VitaDur N. The dentin bond strength of Charisma (1.4 MPa) was inferior (P < .02) to all other materials (2.6 MPa to 4.5 MPa) when thermocycled before testing.     

Total bonding vs selective bonding: marginal adaptation of Class 2 composite restorations

For improving the marginal integrity of composite restorations, a total bonding method has been advocated besides the conventional selective bonding method. Total bonding avoids the placement of a base. The entire internal cavity surface is available for the adhesive bond. Selective bonding involves the placement of a base covering the pulpal floor as well as the pulpoaxial wall. In this study, five dentin/enamel bonding system/composite combinations were used to restore 60 class 2 cavities with their cervical margins below the cementoenamel junction (CEJ); six teeth per material were restored according to the total bonding and the selective bonding methods. Before and after simultaneous thermo-cycling and mechanical loading (TCML) marginal adaptation was evaluated on replicas in the SEM. Microleakage was determined by dye penetration on the original samples after TCML. The data were statistically evaluated with the Mann-Whitney U-test and the Wilcoxon test. The error rates method was applied. In SEM analysis the error rates method indicated a significant difference between the two restoration methods in general. In the pairwise comparisons, no significant differences between the selective bonding and total bonding methods were found for Syntac/Tetric, Gluma 2000/Pekafill, and Gluma/Pekafill. With Scotchbond Multi-Purpose (SBMP) and All-Bond 2 (AB2), total bonding revealed significantly (P < or = 0.01) less gap formation before and after TCML than selective bonding. Accordingly, total bonding showed significantly less (P < or = 0.01) dye penetration with Scotch-bond Multi-Purpose and All-Bond 2 compared to selective bonding. In conclusion, the reduction of microleakage by application of the total bonding method depended upon the bonding system used. Total bonding could be an alternative procedure for the adhesive restoration of class 2 cavities when their gingival margins are apical to the cementoenamel junction, provided the proper system is used and pulp damage is prevented.