Marginal adaptation and microleakage of Procera AllCeram crowns with four cements

PURPOSE: This study investigated the effect of different cements on microleakage and marginal adaptation of porcelain crowns. MATERIALS AND METHODS: Eighty extracted molars were divided into two groups. Teeth in one group were prepared to receive Procera AllCeram crowns, whereas the other group was prepared to receive metal-ceramic crowns. Copings were made following standard techniques, and groups were divided for cementation with zinc phosphate, glass-ionomer, resin-modified glassionomer, or resin cement. Specimens were subjected to thermocycling prior to microleakage testing, then sectioned. Microleakage was scored using a five-point scale; marginal adaptation was assessed with a traveling microscope. RESULTS: A significant association was found between cement type and degree of microleakage. With zinc phosphate, 76% of Procera AllCeram and 90% of metal-ceramic copings exhibited extensive microleakage. With glass-ionomer, 49% of Procera AllCeram and 66% of metal-ceramic copings had 0 microleakage scores; with resin-modified glass-ionomer, 10% of Procera AllCeram and 84% of metal-ceramic copings had 0 microleakage scores. With resin cement, 34% of Procera AllCeram and 96% of metal-ceramic copings exhibited 0 microleakage. Procera AllCeram copings had a significantly larger mean marginal gap (54 microm) compared to metal ceramic (29 microm). CONCLUSION: In both types of crowns, the use of resin cement resulted in the highest percentage of 0 microleakage scores, whereas the zinc phosphate cement resulted in the highest percentage of extensive microleakage.     

3种粘接剂对金属基底冠边缘微渗漏影响的研究

目的 观察使用磷酸锌水门汀(ZPC),玻璃离子水门汀(GIC)和复合树脂粘接剂(CRC)对钴铬烤瓷合金基底冠边缘微渗漏的影响。方法 选择32个离体磨牙,常规制作钴铬烤瓷合金基底冠。随机分为ZPC组,GICⅠ组(不涂凡士林),GICⅡ组(涂凡士林)和CRC组。其中一半标本进行冷热循环。均采用染料渗入法测定冠边缘微渗漏值,并进行统计分析。结果 冷热循环前,GICⅡ组显著小于GICⅠ组和ZPC组。冷热循环后,四组的微渗漏值较循环前均有显著增加,GICⅠ组和GICⅡ组显著小于ZPC组。冷热循环前后,CRC组均显著小于其他三组。结论 CRC对修复体和牙预备体之间微间隙的封闭能力要优于ZPC和GIC。     

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.     

Microleakage in MOD resin composite with three dentin bonding agents

The extent of microleakage under MOD composites was studied when an aluminum oxalate dentin bonding agent (Tenure), a phosphonated resin bonding agent (Bondlite), and a glass-ionomer cement (Ketac Silver) were used. Three groups of 10 extracted molars were prepared with MOD cavities; one box ended on enamel, the other on cementum. In Group 1, Bondlite was applied to dentin and etched enamel before the sample was restored with a light-cured hybrid composite. In Group 2, a 2-mm increment of Ketac Silver was placed in each box before Bondlite and composite. In Group 3, Tenure was applied to dentin before being restored. Teeth were thermal-cycled, stained in silver nitrate, sectioned, and scored for microleakage. Microleakage along the gingival floor was significantly less at enamel margins than at cementum margins in all three groups. All groups showed severe marginal microleakage on cementum.     

The shear bond strength between luting cements and zirconia ceramics after two pre-treatments

This study evaluated the shear-bond strength of 11 luting cements from different material classes to manufactured pre-treated zirconia ceramics (Lava: 97% ZrO2, stabilized with 3% Y2O3). In addition, the influence of the curing method on shear-bond strength was investigated. The cements examined were one zinc-phosphate cement (Fleck's zinc cement), two standard glass-ionomer cements (Fuji I, Ketac-Cem), three resin-modified glass-ionomer cements (Fuji Plus, Fuji Cem, RelyX Luting), four standard resin cements (RelyX ARC, Panavia F, Variolink II, Compolute) and one self-adhesive universal resin cement (RelyX Unicem). The ceramic surface was sand-blasted with 100-microm alumina or tribochemically coated with silica. After bonding procedure, one group was tested after 30 minutes (Time I), the other group was stored in distilled water at 37 degrees C for 14 days and subsequently thermocycled 1000 times (Time II). Statistical analysis was performed by multifactorial ANOVA models with interactions. For multiple pairwise comparisons, the Tukey method was used. After sandblasting, the highest shear-bond strength was obtained for the self-adhesive universal resin cement at 9.7 MPa (Time I) and 12.7 MPa (Time II), respectively. When using the Rocatec system, the highest values were found for one of the resin cements at 15.0 MPa (Time I) and for the self-adhesive universal resin cement at 19.9 MPa (Time II).     

Marginal integrity of partial ceramic crowns within dentin with different luting techniques and materials

This in vitro study evaluated the marginal integrity of partial ceramic crowns (PCCs) luted with or without a resin-coating and compared the results with the marginal sealing of a recently introduced self-adhesive universal resin cement. PCC preparations were performed on 84 extracted human molars, with proximal margins placed 1 mm below the cemento-enamel junction. The PCCs were fabricated from Vita Mark II ceramic (Vita) using the Cerec-3 Unit (Sirona). The prepared teeth were assigned to three groups: (1) conventional luting technique (n=36), (2) resin-coating luting technique (n=36) or (3) recently introduced self-adhesive universal resin cement (n=12). Within these three groups, the following materials were applied: (1) Excite/Variolink II (EVC), ED-Primer/Panavia-F2.0 (PAC), Syntac Classic/ Variolink II (SYC); (2) Excite/Variolink II with Excite/Tetric Flow resin-coating (EVR), ED-Primer/Panavia-F2.0 with Clearfil SE-Bond/ Protect-Liner F resin-coating (PAR), Excite/ Variolink II with Syntac Classic/Tetric Flow resin-coating (SYR); (3) RelyX Unicem (REX). After thermocycling and mechanical loading (TC: 5000 cycles at 5 degrees C/55 degrees C; 30 seconds/cycle; ML:500000 cycles at 72.5 N, 1.6 Hz), microleakage was assessed by evaluating silver staining (%) on multiple tooth sections. Ceramic/composite-, resin-coating/composite- (where applicable) and dentin/composite-interfaces were evaluated separately. The data were statistically analyzed with the Mann-Whitney-U-test and the Error Rates Method. In Groups 1 and 2, the evaluation of microleakage at dentin showed better marginal integrity when the resin-coating technique was applied (EVR, PAR, SYR: 18-53%) than within the conventional luting technique group (EVC, PAC, SYC: 58-67%). However, the lowest microleakage values were found for RelyX Unicem (REX: 15%). In conclusion, resin-coating may improve the marginal sealing within dentin, depending on the materials used. Luting with a self-adhesive universal resin cement showed the best marginal sealing of all groups.     

三种全瓷粘结材料粘结GI-II渗透陶瓷底层冠边缘封闭性研究

目的评价3种全瓷粘结材料粘结后GI-Ⅱ渗透陶瓷底层冠边缘封闭性.方法用3种全瓷粘结材料粘结1 5个GI-Ⅱ渗透陶瓷底层冠,然后用2%亚甲兰溶液浸染1周,剖冠后体视镜下测量边缘微渗漏.结果Dyract Cemplus和Super Bond C&B粘结组边缘封闭性明显优于Hy-Bond glasionomer组.结论Dyract Cemplus和Super Bond C&B是粘结GI-Ⅱ渗透陶瓷冠的理想材料.     

Microleakage of indirect composite inlays. An in vitro comparison with the direct technique.

Microleakage occurring around directly and indirectly made class-II composite restorations was evaluated on extracted human premolars. Before the evaluation was made, the teeth were thermocycled and stained with an organic dye. Direct class-II composite restorations demonstrated extensive microleakage at their dentin cavosurface margins. Indirect class-II composite inlays luted with a dual-curing composite cement displayed much less microleakage than restorations made using the direct technique. The use of glass-ionomer cement rather than composite cement as the luting material resulted in more microleakage. Rather than being a true microleakage, the leakage of glass-ionomer cement might be the result of a diffusion of the water-soluble organic dye in the water-based cement. The results suggest that the indirect composite technique is superior to the direct technique when it comes to reducing microleakage.     

Microleakage of various cementing agents for full cast crowns.

OBJECTIVES: To evaluate microleakage and marginal gaps in full cast crown restorations bonded with six different types of cementing agents. METHODS: Sixty non-carious human premolars and molars were prepared in a standardized manner for full cast crown restorations. The mesial and distal margins were located in dentin, while the vestibular and palatal/lingual margins were located in enamel. Crowns were made from a high-gold alloy using a standardized technique. The specimens were randomized to six groups of cementing agents: one zinc-phosphate cement (Harvard cement), one conventional glass-ionomer cement (Fuji I), one resin-modified glass-ionomer cement (Fuji Plus), two standard resin cements (RelyX ARC, Panavia F), and one self-adhesive universal resin cement (RelyX Unicem). After 4 weeks of storage in distilled water at 37 degrees C, the specimens were subjected to 5000 thermocycles ranging from 5 to 55 degrees C. Then, they were placed in a silver nitrate solution, embedded in resin blocks, and vertically cut in buccolingual and mesiodistal direction. Subsequently, the objects were evaluated for microleakage and marginal gap using a high-resolution digital microscope camera. RESULTS: A number of inter-group differences were statistically significant. RelyX Unicem showed the smallest degree of microleakage both in enamel and in dentin. Panavia F und RelyX Unicem were associated with significantly larger marginal gaps than all other cementing agents. No association was observed between microleakage and marginal gap other than a weak direct correlation when using Harvard cement on enamel. SIGNIFICANCE: The cementing agents investigated revealed different sealing abilities. These differences were not associated with specific types of materials.     

Marginal leakage around V-shaped cavities restored with glass-ionomer cements: an in vitro study.

The object of this investigation was to assess the degree of marginal leakage around V-shaped cervical glass-ionomer cement restorations and compare it to that around composite resin restorations. Three different glass-ionomer cements and one composite resin control were assessed by means of dye penetration. Severe microleakage at the occlusal margins was found in 70% of the glass-ionomer cement restorations, but in only 10% of the composite resin restorations. A considerable amount of dye penetration was observed at the cervical margins of all restorations, including the controls. None of the glass-ionomer cements tested showed superiority in preventing marginal leakage occlusally or gingivally.     

Marginal seal of injection-molded ceramic crowns cemented with three adhesive systems

This in vitro investigation evaluated the marginal seal of an injection-molded ceramic crown system used in combination with three adhesive luting systems. One of these systems was a glass-ionomer cement and the other two were based on composite resin materials. One of the latter materials is claimed by the manufacturer to bond to tooth structure and also to porcelain. The final luting material was used in conjunction with a commercially available porcelain bonding system and specific dentin bonding pretreatments. Following thermocycling, the marginal seal of the crowns was tested by use of a chemical marker intrusion technique. The extent of leakage along the sectioned crown/luting agent/tooth structure interfaces was recorded by using digital imaging microscopy. Minimal microleakage was demonstrated with the composite luting cement used in association with specific porcelain and dentin bonding pretreatments.     

Vertical misfit of laser-sintered and vacuum-cast implant-supported crown copings luted with definitive and temporary luting agents

Objectives. This study aimed to evaluate the vertical discrepancy of implant-supported crown structures constructed with vacuum-casting and Direct Metal Laser Sintering (DMLS) technologies, and luted with different cement types. Study Design. Crown copings were fabricated using: (1) direct metal laser sintered Co-Cr (LS); (2) vacuum-cast Co-Cr (CC); and (3) vacuum-cast Ti (CT). Frameworks were luted onto machined implant abutments under constant seating pressure. Each alloy group was randomly divided into 5 subgroups (n = 10 each) according to the cement system utilized: Subgroup 1 (KC) used resin-modified glass-ionomer Ketac Cem Plus; Subgroup 2 (PF) used Panavia F 2.0 dual-cure resin cement; Subgroup 3 (RXU) used RelyX Unicem 2 Automix self-adhesive dual-cure resin cement; Subgroup 4 (PIC) used acrylic/urethane-based temporary Premier Implant Cement; and Subgroup 5 (DT) used acrylic/urethane-based temporary DentoTemp cement. Vertical misfit was measured by scanning electron microscopy (SEM). Two-way ANOVA and Student-Newman-Keuls tests were run to investigate the effect of alloy/fabrication technique, and cement type on vertical misfit. The statistical significance was set at α = 0.05. Results. The alloy/manufacturing technique and the luting cement affected the vertical discrepancy (p < 0.001). For each cement type, LS samples exhibited the best fit (p < 0.01) whereas CC and CT frames were statistically similar. Within each alloy group, PF and RXU provided comparably greater discrepancies than KC, PIC, and DT, which showed no differences. Conclusions. Laser sintering may be an alternative to vacuum-casting of base metals to obtain passive-fitting implant-supported crown copings. The best marginal adaptation corresponded to laser sintered structures luted with glass-ionomer KC, or temporary PIC or DT cements. The highest discrepancies were recorded for Co-Cr and Ti cast frameworks bonded with PF or RXU resinous agents. All groups were within the clinically acceptable misfit range. Key words:Dental alloy, laser sintering, implant-supported prostheses, vertical discrepancy, vertical misfit.     

In vitro evaluation of wall-to-wall adaptation of a self-adhesive resin cement used for luting gold and ceramic inlays

PURPOSE: This in vitro study evaluated the wall-to-wall adaptation of a new self-adhesive resin-based cement (RelyX Unicem) in comparison with that of other cements when luting gold and porcelain inlays in standardized Class II cavities in extracted teeth. MATERIALS AND METHODS: In each experimental group (n = 10), a different combination of inlay and luting material was tested. Group 1: Porcelain Empress II (Ell) and RelyX Unicem (U); group 2: Ell and resin-based cement Variolink II in combination with primer and bonding Excite DSC; group 3: gold inlays (G) and U; group 4: G and Harvard zinc-oxy-phosphate cement; group 4: G and glass-ionomer cement Fuji Cem. After storage and thermocycling, microleakage testing was carried out and dye penetration was examined at the occlusal and cervical margins of each inlay. The differences in microleakage score were tested for statistical significance first comparing all groups, then pooling the groups for inlay material (Kruskal-Wallis nonparametric ANOVA and Mann-Whitney U test, p < 0.05). SEM observations of the tooth/cement/restoration interfaces were also made in each group. RESULTS: Harvard cement had the highest microleakage. The sealing ability exhibited by RelyX Unicem was satisfactory with both gold and porcelain inlays, and comparable to that of Fuji Cem and Variolink II. CONCLUSION: RelyX Unicem achieved an adequate seal on both enamel and dentin when used to lute in vitro gold and porcelain inlays.     

Early marginal microleakage in class II resin composite restorations

The aim of this study was to evaluate in vitro the early marginal microleakage around conventional and sandwich Class II (MOD) restorations. Ten different combinations of dentin bonding agents, glass-ionomer cements, and posterior resin composites were used. Class II cavities were prepared in freshly extracted third molars whose root surfaces had previously been coated. All gingival margins were prepared at the cementum-enamel junction. Teeth were filled by use of a multi-incremental technique, finished with discs, and immediately immersed in 2% erythrosin B for 12 h at 37 degrees C. Three transverse sections were made at 0.5 mm, 2 mm, and 3.5 mm over the cementum-enamel margin and evaluated under a stereomicroscope. Microleakage was scored linearly along the dentin/enamel-restoration interface. Sections at the cementum-enamel level showed significantly higher microleakage than the other two. Significant differences were observed between the various combinations of materials. Early marginal microleakage in Class II restorations depends not only on filling technique and on dentin bonding systems but also on the resin composite. Glass-ionomer cements significantly reduce early marginal microleakage in Class II restorations.     

不同粘接剂对二氧化锆桩固位力的影响

目的探讨不同粘接剂对二氧化锆桩与根管内牙本质粘接强度的影响。方法将60颗完整无龋坏的离体上颌中切牙自釉牙骨质界处截断牙冠,根管桩道预备,制作二氧化锆桩核。60颗牙随机分为6组,分别用磷酸锌水门汀、聚羧酸锌水门汀、玻璃离子水门汀i、Bond加LuxaCore双固化树脂、RelyX Unicem树脂、32%磷酸加ESPE RelyX Unicem树脂粘固二氧化锆桩核。万能力学试验机进行推出测试,记录粘接强度,并对数据行统计学分析。结果 32%磷酸加ESPE RelyX Unicem树脂组、ESPE RelyX Unicem树脂组i、Bond加Luxa Core树脂组、聚羧酸锌水门汀组、玻璃离子水门汀组、磷酸锌水门汀组的二氧化锆桩粘接强度分别为（15.06±1.80）MPa、（11.57±1.33）MPa（、10.42±1.24）MPa（、7.30±1.05）MPa（、6.99±0.87）MPa（、3.97±0.95）MPa,固位力依次降低。其中32%磷酸加ESPE RelyX Unicem树脂组的固位力显著高于其他组,两两比较差异均有统计学意义（P〈0.05）;ESPE RelyX Unicem树脂组与Luxa Core树脂组之间（P=0.590）,聚羧酸锌组和玻璃离子组之间（P=0.490）的差异均无统计学意义;磷酸锌水门汀的粘接强度最低,与其它组比较差异均有统计学意义（P〈0.05）。结论临床粘固二氧化锆桩,树脂类粘接剂固位力较强,自粘接系统加用酸蚀技术可以显著提高二氧化锆桩在根管内的粘接强度。     

4种玻璃离子水门汀对ITI基台与金属内冠之间粘接力的比较研究

目的：研究4种玻璃离子类水门汀对ITI种植系统标准颈粘接固位基台和金属内冠之间的粘接力。方法将10只金属内冠与10只I T I标准颈粘接固位基台分别使用以下4种水门汀进行交叉粘固：A组为玻璃离子水门汀（日本）;B组为树脂加强型玻璃离子水门汀（美国）;C组为暂时粘固用玻璃离子水门汀（日本）;D组为玻璃离子水门汀（德国）;粘固后测试并记录样本粘接力（N）,同时观察并记录粘固界面的断裂模式,最后,对粘接力进行统计学处理。所有内冠和基台经清洗后重复使用。结果4种水门汀的粘接力及由大至小的排列顺序为C组（183.6±29.4） N〉D组（153.4±36.2） N〉B组（144.4±41.1） N〉A组（109.9±25.7）N,其中C组的粘接力最高,A组的粘接力最低,A组显著低于其它3种水门汀（P〈0.05）。对样本的断裂面观察显示,A组和D组样本断裂面发生在水门汀和基台表面之间,而B组和C组样本的断裂面则呈现混合断裂的模式。结论2种玻璃离子水门汀和树脂加强型玻璃离子水门汀都具有临床可接受的粘接力,而暂时粘固用玻璃离子水门汀因粘接力太大,不适用对种植牙冠进行暂时粘固。     

In vitro evaluation of microleakage of indirect composite inlays cemented with four luting agents

STATEMENT OF PROBLEM: Microleakage around dental restorations is implicated in the occurrence of secondary carious lesions, adverse pulpal response, and reduced restoration longevity. PURPOSE: The aim of this in vitro study was to evaluate the microleakage of indirect resin composite inlays cemented with 4 luting agents. MATERIAL AND METHODS: Standardized Class V inlay preparations overlapping the cemento-enamel junction were prepared on the buccal and lingual surfaces of 40 extracted human mandibular third molars. Eighty postpolymerized, heat-treated resin composite inlays (Targis, 72 specimens, 8 controls) were processed in stone replicas and cemented into the preparations using 4 luting agents (n = 18 + 2 controls for each cement group): a resin composite used with a bonding agent (Variolink II/Excite), a resin composite used with a self-etching primer, but without bonding agent (Panavia F/ED Primer), a modified resin composite used with a bonding agent (Resinomer/One Step), and a resin-modified glass-ionomer cement (Fuji Plus). Thirty-six inlays (n = 9 + 1 control) were subjected to thermal cycling (2000 cycles, 5 degrees C/55 degrees C), whereas the other 36 were not. All the teeth were then immersed in 1% methylene blue dye solution for 48 hours. Microleakage score, margin location (enamel/cementum), thermal cycling history, and preparation location (buccal/lingual) were analyzed using a multivariate model (alpha = .05). Multivariate analysis was performed using a polychotomous logistic regression. RESULTS: The preparation location had no significant effect on dye penetration. The margin location (enamel or cementum) and the thermal cycling had a significant effect on microleakage (odds ratios [ORs] = 17.6 and 8.04, respectively). In comparing the 3 resin-based luting agents (Variolink II, Panavia F, and Resinomer) to Fuji Plus, Panavia F exhibited the lowest significant overall microleakage (OR = 0.09), followed by Variolink II (significant OR equal to 0.43), whereas Resinomer demonstrated the greatest significant overall microleakage (OR = 1.35). CONCLUSION: Within the experimental conditions of this in vitro study, thermal cycling significantly increased microleakage (OR = 8.04). The overall microleakage at the enamel margins was significantly lower than the overall microleakage at the cementum margins for the 4 luting agents tested (OR = 17.6).     

Marginal fit and microleakage of cast and metal laser sintered copings—An in vitro study

PurposeThis study aimed to compare the marginal fit and microleakage of metal laser sintered Co–Cr alloy copings and conventional cast Ni–Cr alloy copings using a stereomicroscope.MethodsForty extracted maxillary premolars were randomly divided into two groups. One group was subjected to coping fabrication using conventional lost wax (LW) technique while the other group was subjected to coping fabrication using metal laser sintering (MLS) technology. The marginal fit of these copings were compared before and after ceramic addition using images obtained with a steromicroscope and an ImageJ analysis software. All the specimens were cemented using Type 1 glass ionomer cement and were subjected to thermocycling. The specimens were evaluated for microleakage using stereomicroscope and 2% methylene blue die used as a tracer. The data were subjected to statistical analysis using paired t-test, Mann–Whitney test and Chi-Square test.ResultsThe mean marginal fit of copings before and after ceramic addition in Group B (MLS) was better than the copings in Group A (LW) and was statistically significant (P < 0.05). The influence of ceramic firing had a significant (P < 0.05) increase in mean marginal gap in Group A (LW) but not in Group B (MLS). And the difference in mean microleakage between the groups was not statistically significant (P ≥ 0.05).ConclusionThe copings fabricated using MLS technique had a better marginal fit and an observable decrease in microleakage when compared to the copings fabricated using the conventional lost wax (LW) technique.     

Shear bond strength between nickel-chromium and human dentine using a dual-cure, self-adhesive universal resin luting agent

The adhesive property of a dual-cure, self-adhesive universal resin luting agent (Rely X Unicem, 3M ESPE) between nickel-chromium (Ni-Cr) and human dentine was compared with three conventional resin luting agents (Calibra, Dentsply; Panavia-F, Kuraray; All-bond 2 C & B cement, Bisco). Ten Ni-Cr rods were bonded to human dentine with each of the four luting agents, and were subjected to shear bond test. Results showed that there was no significant difference in shear bond strengths among the luting agents. A dual-cure, self-adhesive universal resin luting agent was shown to have comparable adhesive property between Ni-Cr and human dentine as three other conventional resin luting agents. Given the simplicity of use of the dual-cure, self-adhesive universal resin luting agent, it appears to be promising in clinical applications.     

Vertical discrepancy and microleakage of laser-sintered and vacuum-cast implant-supported structures luted with different cement types

Objectives

This study aimed to evaluate the vertical misfit and microleakage of laser-sintered and vacuum-cast cement-retained implant-supported frameworks.

Methods

Three-unit implant-fixed structures were constructed with: (1) laser-sintered Co–Cr (LS); (2) vacuum-cast Co–Cr (CC); and (3) vacuum-cast Pd–Au (CP). Every framework was luted onto 2 prefabricated abutments under constant seating pressure. Each alloy group was randomly divided into three subgroups (n = 10) according to the cement used: (1) Ketac Cem Plus (KC); (2) Panavia F 2.0 (PF); and (3) RelyX Unicem 2 Automix (RXU). After 30 days of water ageing, vertical discrepancy was measured by SEM, and marginal microleakage was scored using a digital microscope. Three-way ANOVA and Student–Newman–Keuls tests were run to investigate the effect of alloy/fabrication technique, FDP retainer, and cement type on vertical misfit. Data for marginal microleakage were analysed with Kruskal–Wallis and Dunn's tests (α = 0.05).

Results

Vertical discrepancy was affected by alloy/manufacturing technique and cement type (p < 0.001). Despite the luting agent, LS structures showed the best marginal adaptation, followed by CP, and CC. Within each alloy group, KC provided the best fit, whilst the use of PF or RXU resulted in no significant differences. Regardless of the framework alloy, KC exhibited the highest microleakage scores, whilst PF and RXU showed values that were comparable to each other.

Conclusions

Laser-sintered Co–Cr structures achieved the best fit in the study. Notwithstanding the framework alloy, resin-modified glass-ionomer demonstrated better marginal fit but greater microleakage than did MDP-based and self-adhesive dual-cure resin cements. All groups were within the clinically acceptable misfit range.

Clinical significance

Laser-sintered Co–Cr may be an alternative to cast base metal and noble alloys to obtain passive-fitting structures. Despite showing higher discrepancies, resin cements displayed lower microleakage than resin-modified glass-ionomer. Further research is necessary to determine whether low microleakage scores may guarantee a suitable seal that could compensate for misfit.