Marginal Seating of Zirconium Monolithic Crown Restorations Utilising Different Types of Luting Agents - A Comparative Study.

Marginal adaptation is an important factor affecting the longevity of all-ceramic restorations, although the effects of different fabrication steps on marginal adaptation at various stages of fabrication are not fully understood. The purpose of this study was to assess with an in vitro model whether In-Ceram alumina (IA) or In-Ceram zirconia (IZ) copings produced by the CAD/CAM method would be clinically acceptable, and to evaluate the effect of each fabrication step (post-milling, post-trimming, and post-glass infiltration) on the marginal discrepancy of the coping. A melamine tooth was prepared, duplicated, poured with inlay wax, and then cast with metal to fabricate a master die. An InLab 3D system was used to scan the master die and to design and mill the copings. Thirty IA and IZ copings each were developed with thicknesses of 0.6 mm and a 30-μm thick computer luting space. Epoxy resin replicas of the master die were fabricated, and the vertical and horizontal marginal discrepancies were measured using a Micro-Vu optical microscope at three stages of the fabrication (post-milling, post-trimming, post-infiltration). One-way ANOVA was used to analyze the data between the three stages of fabrication for each marginal discrepancy, and a t-test was used to compare vertical and horizontal marginal discrepancies (after glass infiltration) between IZ and IA copings There were no significant differences (p > 0.05) in the vertical marginal discrepancies (μm) between IA (36 ± 14) and IZ (40 ± 14) copings after glass infiltration. ANOVA (comparing three stages within horizontal marginal discrepancy for IZ copings) showed that post-milling (40 ± 26) > post-trimming (23 ± 11) = post-infiltration (19 ± 13). ANOVA (comparing three stages within vertical marginal discrepancy for IZ copings) showed that post-milling (53 ± 12) = post-trimming (47 ± 13) > post-infiltration (36 ± 14). ANOVA (comparing three stages within horizontal marginal discrepancy for IA copings) showed that post-milling (52 ± 28) > post-trimming (30 ± 16) > post-infiltration (30 ± 16). ANOVA (comparing three stages within vertical marginal discrepancy for IA copings) showed that post-milling (54 ± 13) = post-trimming (56 ± 26) > post-infiltration (40 ± 14). There was no significant difference in the marginal adaptation of both material copings. After the trimming process, the glass infiltration firing cycle improved the vertical marginal discrepancy for both IZ and IA copings. Clinical implications. IA and IZ copings fabricated by CAD/CAM technology have an acceptable marginal fit as documented in the literature, and the glass infiltration process improves the marginal fit after machining.

The survival of fixed prosthodontic restorations depends on the state of the marginal adaptation. Marginal gaps can create a favourable condition for biofilm deposition, thereby contributing to the development of caries and periodontal disease. The longevity of fixed prosthodontic restorations depends on the condition of the marginal adaptation to the abutment teeth. The presented work aimed to study, evaluate and compare the marginal adaptation of All-Ceramic crowns fabricated using conventional laboratory procedures with those fabricated using the CAD/CAM technology.To compare the marginal fit and adaptation of All- Ceramic crowns obtained by conventional techniques and crowns obtained by CAD/CAM technique. The presented study focused on a total of 20 samples divided into two groups viz. Group I (Conventional) and Group II (CAD/CAM) having 10 sample each. The samples were prepared with the straight abutment having a standardized collar height of 2mm, HIOSSEN that was mounted on acrylic blocks using implant analogue, HIOSSEN. A set of crowns was produced by 5-axis milling lithium disilicate using glass-ceramic blocks with laboratory fabrication methods. Another set of zirconia crowns was produced using CAD/CAM technology. Circumferential marginal gap measurements were taken at 12 measurement locations on the hexagonal die marked equidistant to each other. Both the samples were measured for marginal discrepancy at under the stereomicroscope.The results obtained showed that the mean vertical gap for the group II samples showed the least variation in the marginal discrepancy. Although the mean obtained for both the groups showed that the mean vertical marginal discrepancy was within the clinically acceptable level.It can be concluded that within the limitation of the study the data obtained showed that The Mean vertical gap was the maximum for Group I (Conventional group) i.e. 49.25 µm showing maximum variation in marginal fit. While the CAD/CAM Group had shown least vertical marginal discrepancy which depicts statistically significant better marginal fit than those fabricated using conventional laboratory procedures.

Effect of different finish line preparations on the marginal and internal adaptation of cobalt-chromium metal alloy copings fabricated by using CAD-CAM technology: A systematic review and meta-analysis

Statement of the problem; the use of pressable and CAD/CAM ceramics have been lately frequently used in fixed prosthodontics. However, information about their marginal fit and internal adaptation are is little.Purpose: Marginal adaptation and internal adaptation are an important factor affecting the longevity of all ceramic restorations, so the purpose of the study was to evaluate the effect of restorations fabricated with CAD/CAM technology, the heat-press technique ceramic and luting agent on the Marginal Fit and Internal Adaptation of all Ceramic crowns.Materials & methods: A total of 20 mandibular Second premolars teeth were used in this study and divided into two groups according to technique of fabrication of ceramic crowns as follow: Machinable ceramics (M). IPS E-max CAD blocks have used for fabrication of ceramic crowns. (n=10), Pressable ceramics (P). IPS E-max press ingots have used for fabrication of ceramic crowns. (n=10).Each group is divided into two subgroups according to the type of resin cement used as follow: Group T: Ceramic crowns are cemented with total etch Cement-it resin cement (n=5). Group S: Ceramic crowns are cemented with Rely-x self-adhesive resin cement (n=5). A silicone replica was obtained to measure marginal and internal adaptation of each all-ceramic crown before luting, and they were sectioned vertically in mesiodistal direction. Marginal and internal adaptations were measured using computerized light microscope at 100 × magnification. Data were presented as mean and standard deviation (SD) values. Regression model with repeated measures Analysis of Variance two ways (ANOVA) was used in testing significance for the effect of ceramic type and cement type.Results: related to marginal gap, it was found that press group recorded statistically significant (P 0.05) higher (54.77± 0.8 μm) than total etch cement (50.3± 5.88 μm).while related to internal adaptation, totally it was found that CAD group recorded statistically significant (P<0.05) higher internal gap mean value (87.45 ± 15.4 μm) than press group (36.64± 5.15 μm) and it was found that internal gap mean value of total etch cement was statistically significant (P<0.05) higher (67.24± 11.14 μm) than self-adhesive cement (56.85± 9.4 μm).Conclusion: Within the limitation of this study, The CAD group recorded statistically significant high vertical marginal fit than press group. The cement type has no effect on the marginal fit. The press group recorded statistically significant high internal fit than CAD group.

The purpose of this study was to investigate the vertical marginal discrepancy (VMD) and residual excess cement (REC) of cementable and screwmentable monolithic zirconia crowns cemented with different types of cement. Abutments were attached to 40 implant analogues. Crowns were created using computer-aided design/computer-aided manufacturing technology from monolithic zirconia blocks, either with or without a screw access hole (SAC). Crowns created both ways were split into two groups and cemented with resin and zinc polycarboxylate cement under a 5-kg weight. VMD and REC values were evaluated using an X20 zoom stereomicroscope. Data were analysed using two-way ANOVA and the Bonferroni test. According to the two-way ANOVA results, REC measurements differed significantly in the crown design and cement groups. However, whilst VMD values were significantly different in both crown design groups, there was no significant difference in the cement groups. According to the Bonferroni test results, the highest REC (157.241 ± 44.29µm) and VMD (68.052 ± 16.19µm) values were found in the crowns without SAC and cemented with zinc polycarboxylate. Screwmentable crowns are more effective than cementable crowns in reducing REC and VMD. Whilst polycarboxylate cement reduces VMD in screwmentable crowns, resin cement is more suitable for cementable crowns.

Statement of the problem; the use of pressable and CAD/CAM ceramics have been lately frequently used in fixed prosthodontics. However, information about their marginal fit and internal adaptation are is little.Purpose: Marginal adaptation and internal adaptation are an important factor affecting the longevity of all ceramic restorations, so the purpose of the study was to evaluate the effect of restorations fabricated with CAD/CAM technology, the heat-press technique ceramic and luting agent on the Marginal Fit and Internal Adaptation of all Ceramic crowns.Materials & methods: A total of 20 mandibular Second premolars teeth were used in this study and divided into two groups according to technique of fabrication of ceramic crowns as follow: Machinable ceramics (M). IPS E-max CAD blocks have used for fabrication of ceramic crowns. (n=10), Pressable ceramics (P). IPS E-max press ingots have used for fabrication of ceramic crowns. (n=10).Each group is divided into two subgroups according to the type of resin cement used as follow: Group T: Ceramic crowns are cemented with total etch Cement-it resin cement (n=5). Group S: Ceramic crowns are cemented with Rely-x self-adhesive resin cement (n=5). A silicone replica was obtained to measure marginal and internal adaptation of each all-ceramic crown before luting, and they were sectioned vertically in mesiodistal direction. Marginal and internal adaptations were measured using computerized light microscope at 100 × magnification. Data were presented as mean and standard deviation (SD) values. Regression model with repeated measures Analysis of Variance two ways (ANOVA) was used in testing significance for the effect of ceramic type and cement type.Results: related to marginal gap, it was found that press group recorded statistically significant (P 0.05) higher (54.77± 0.8 μm) than total etch cement (50.3± 5.88 μm).while related to internal adaptation, totally it was found that CAD group recorded statistically significant (P<0.05) higher internal gap mean value (87.45 ± 15.4 μm) than press group (36.64± 5.15 μm) and it was found that internal gap mean value of total etch cement was statistically significant (P<0.05) higher (67.24± 11.14 μm) than self-adhesive cement (56.85± 9.4 μm).Conclusion: Within the limitation of this study, The CAD group recorded statistically significant high vertical marginal fit than press group. The cement type has no effect on the marginal fit. The press group recorded statistically significant high internal fit than CAD group.

Marginal and internal fit of CAD-CAM composite resin and ceramic crowns before and after internal adjustment

Introduction Marginal adaptation is a key factor in the biological and mechanical success of fixed partial dentures (FPDs). This study aimed to clinically compare the marginal adaptation of metal-ceramic and all-ceramic FPDs cemented with resin-modified glass ionomer cement (RMGIC) and self-adhesive resin cement. Materials and methods This prospective clinical observational study included 60 patients who required three-unit posterior FPDs. The patients were allocated into two groups: metal-ceramic (n = 30) and all-ceramic (n = 30). Each group was subdivided according to the luting cement used: RMGIC or self-adhesive resin cement (n = 15 each). Standardized clinical and laboratory protocols were used. Marginal adaptation was assessed using the modified United States Public Health Service (USPHS) criteria immediately after cementation and at three months by calibrated, blinded examiners. Data were analyzed using non-parametric tests and analysis of covariance (ANCOVA), with significance set at p < 0.05. Results At baseline, all groups demonstrated a clinically ideal marginal adaptation, with a median USPHS score of 1. Mean baseline scores ranged from 0.73 to 1.00 across subgroups. At three months, metal-ceramic FPDs cemented with RMGIC showed the highest mean USPHS score (2.6 ± 0.51), indicating greater marginal discrepancy. All-ceramic FPDs cemented with self-adhesive resin cement demonstrated the lowest mean score (0.87 ± 0.83), followed by metal-ceramic FPDs with self-adhesive resin cement (1.73 ± 0.70). Intergroup comparisons showed significantly better marginal adaptation in all-ceramic restorations than in metal-ceramic restorations (p < 0.001). Cement type also significantly influenced the outcomes, with self-adhesive resin cement performing better than RMGIC (p < 0.001). No significant interaction was observed between the restoration type and cement type (p = 0.913). Conclusion All-ceramic FPDs demonstrated superior early marginal adaptation compared with metal-ceramic restorations. The use of self-adhesive resin cement resulted in improved marginal integrity irrespective of the restoration type.

In vitro evaluation of the marginal integrity of CAD/CAM interim crowns

Background: The accuracy of fitness of any dental casting is imperative for the success of any prosthodontic treatment. From the time that dental casting was first introduced, efforts have been made to produce more accurate and better fitted castings with minimal marginal discrepancy. The aim of this in vitro study was to evaluate the effects of three different investing and burnout techniques on the vertical marginal discrepancies ofceramometalcopings invested with two types of phosphatebonded investments. Materials and methods: Sixty wax patterns were fabricated on a standardized prepared brass die representing an upper central incisor by the aid of a custom-made split mold. Three different investing and burnout techniques were applied for an Iraqi investment and a commercial type; Group I:Ring investing with conventional burnout technique (RC);Group II: Ringless investing with conventional burnout technique (RLC);Group III: Ring investing with accelerated burnout technique (RA).Twenty wax patterns of each group were divided into two subgroups according to the type of investment material used (10 for each subgroup) represented as (B) for the BellaStar XL and (W) for the WYMvest investments. Complete castings were finished and seated on the metal die. The accuracy of fit of each coping was determined by measuring the vertical marginal discrepancies between the finish line on the metal die and the margins of each coping at four specific reference points on the labial, mesial, palatal, and distal aspects of the die by the aid of a light microscope supplied with a digital camera.The arithmetic mean of each three records was computed and regarded as the amount of the marginal discrepancy of each coping and was used as a unit for the statistical analysis. Results: Mean marginal accuracy for W(RLC)was found to be the least (13.839+4.5724 um) while the highest mean value related to B(RLC) (29.033+2.102 um). In general, ANOVA test showed significant results among the mean values of the Binvestment subgroups while LSD test showed non-significance between the (RA) and both the (RC) and (RLC) subgroups. On the other hand, significance was present between the (RLC) and (RA)of the Winvestment subgroups while non-significance was located between the (RC) and both the (RLC) and (RA) subgroups. Comparing similar subgroups of the two tested investments, the Student's t-test showed non-significance between the (RC) subgroups while high significance was located between the (RLC) and (RA) subgroups respectively.Concerning the vertical marginal discrepancy of the copings, applying the (RC) technique for both investments caused non-statistical significance between the labial, mesial, palatal, and distal aspects.The (RLC) technique caused high significance between the four aspects, while the (RA) technique caused non-significance between the labial aspect only and the others. Conclusion: The Iraqi investment generally produced less vertical marginal discrepancies (using the three different investing and burn-out techniques) than the commercial investment.In order to achieve a better marginal fit, it seems that ceramometalcopings invested with the commercial investment tested are better be cast using the conventional ring investing and burnout technique.

ObjectivesThis study compared the silicone replica method with swept-source optical coherence tomography (SS-OCT) to analyze marginal adaptation and investigated the effect of the light incidence angle of SS-OCT on measurement precision.Materials and methodsA typodont-prepared mandibular right first molar was scanned using an intraoral scanner (Trios 3). Fourteen crowns were fabricated from CAD/CAM resin blocks (Katana Avencia P) using a 5-axis milling machine (DWX-50). Marginal adaptation at the buccal, lingual, mesial, and distal points was assessed using the silicone replica method and SS-OCT at light incidence angles of 60°, 75°, and 90°. Statistical comparisons were performed using two-way analysis of variance (ANOVA) and t-tests with Bonferroni correction, and t-tests at a significance level of 0.05.ResultsAt 60°, SS-OCT showed significantly larger marginal discrepancies than the silicone replica method at the buccal, lingual, and mesial points (p < 0.05). At 75°, only the lingual point showed a significantly larger value than the silicone replica method (p < 0.05). At 90°, no significant differences were observed between the SS-OCT and silicone replica methods (p > 0.05). Marginal discrepancy values increased as the angle changed from 90° to 75° to 60°, with significant differences between 60° and 75° and between 60° and 90° at the buccal and lingual points (p < 0.05).ConclusionsSS-OCT is a viable alternative to the silicone replica method for assessing marginal adaptation at an incidence angle of 90 °.Clinical relevanceSS-OCT, a non-invasive method, has the potential to be applied clinically for evaluating marginal fit in indirect restorations in vivo.

A comparison of the marginal and internal fit of porcelain laminate veneers fabricated by pressing and CAD-CAM milling and cemented with 2 different resin cements

Influence of collar height of definitive restoration and type of luting cement on the amount of residual cement in implant restorations: A clinical study

Objectives: The purpose of this study was to compare the retention strength of implant-supported crowns produced by traditional lost-wax, direct metal laser sintering, CAD/CAM technique by using three different luting cements. Materials and Methods: Ninety standard titanium abutments screwed to analogs then mounted in acrylic resin. Samples divided into three main groups according to the manufacturing technique (N=30). Then groups divided into three subgroups based on the cement type used (n=10). The specimens subjected to the pull-out test by using an universal testing machine at a 1 mm/min crosshead speed. The highest pull-out strength values were recorded in Newton and statistical analyzes were performed by using Two-way ANOVA test and multiple comparison test with Bonferroni correction at a significance level of 0.05. Results: The two-way analysis of variance revealed that the fabrication technique and cement type had a significant effect on pull-out strength (p 0.05). The highest pull-out strength was found in the laser sintering group, while the conventional technique had the lowest values. Within the subgroups self-adhesive resin cement had the highest pull-out strength, traditional cement subgroup had the lowest. Conclusions: Fabrication technique and cement type have statistically significant effect on the retention of the implant-supported crowns.

Background The marginal fit is one of the key factors for the clinical success of dental restorations. Ideal marginal adaptation can reduce gingival irritation and cement dissolution. After clinically examining over 1000 metal ceramic crowns, McLean and von Fraunhofer reported that marginal discrepancies up to 120 μm were acceptable. Other clinicians considered a marginal fit of 100 μm to be clinically acceptable for the longevity of the restorations. Aim/Hypothesis The purpose of this study was to examine the correlation between the finish line designs and the marginal adaptation of nonprecious metal alloy coping produced by different digital manufacturing methods. Material and Methods For fabrication of two master models with different finish lines, the master models were designed by 3-D designing software program based on the abutment preparation principle and titanium master models were milled by computer aided manufacturing. Nonprecious metal alloy copings were made respectively from each master model with three different methods, selective laser sintering (SLS), milling and casting by CAD CAM. 12 copings were made by each method resulting in 72 copings in total. The marginal fit was evaluated by measuring the gap between the cavosurface margin of the abutment die and the edge of the crown margin on mesial, buccal, distal and lingual site of each specimen. The measurement was conducted at 40 determined reference points along the circumferential margin with the confocal laser scanning microscope at magnification ×150. Results Mean values of marginal gap of laser sintered copings were 11.8 ± 7.4 μm for deep chamfer margin and 6.3 ± 3.5 μm for rounded shoulder margin and the difference between them was statistically significant (P < 0.0001). Mean values of marginal gap of milled copings were 53.9 ± 27.8 μm for deep chamfer margin and 48.6 ± 30.1 μm for rounded shoulder margin and the difference between them was not significant (P = 0.279). Mean values of marginal gap of casted copings were 18.8 ± 20.2 μm for deep chamfer margin and 33 ± 20.5 μm for rounded shoulder margin and the difference between them was significant (P = 0.0004). Meanwhile, the marginal fit depending on the manufacturing method was significantly different regardless of finish line design. Selective laser sintering group exhibited the best marginal adaptation among three manufacturing methods and digitalized casting group showed better marginal fit than milling group. Conclusions and Clinical Implications (i) The variation of finish line design influences the marginal adaptation of laser sintered metal coping and casted metal coping. (ii) Laser sintered copings with rounded shoulder margin had better marginal fit than deep chamfer margin. (iii) Casted copings with deep chamfer margin had better marginal fit than rounded shoulder margin. (iv) According to the manufacturing method, SLS system showed the best marginal fit among three different methods. Casting and milling method followed that in order.