Porcelain Fused Research Articles

REVIVING YOUR PORCELAIN SMILE: A GUIDE TO INTRAORAL REPAIR OF FIXED PORCELAIN PARTIAL DENTURES: A LITERATURE REVIEW

Background: Porcelain or ceramic-based materials are popular in dentistry due to their aesthetic appeal and biocompatibility. However, chipping or fractures in fixed partial dentures can disrupt aesthetics and functionality. Intraoral repair offers a cost-effective and time-saving solution. Objective: This study aims to guide practitioners in managing chipping crowns, saving time and costs while ensuring satisfactory outcomes for patients. Method: The review included articles on intraoral repair of porcelain fixed partial dentures, published in peer-reviewed journals, available in English, and including clinical trials, case reports, and reviews. Exclusions were non-dental studies, non-English articles, and studies focusing on temporary restorations. Data on the etiology of chipping, necessary tools, and management steps were collected. Result: Porcelain Fused to Metal (PFM) denture repairs are difficult due to color matching and procedural complexity. Repairing Lithium Disilicate dentures is moderately challenging, requiring meticulous surface preparation. The most complex repairs are for Zirconia-based prostheses, needing specialized equipment and advanced techniques for a durable bond. Conclusion: Intraoral repair techniques provide a quick, precise, and comfortable solution for patients. Understanding the stages of intraoral repair allows clinicians to achieve optimal functional and aesthetic results. Clinicians should evaluate their expertise and resources to select the appropriate technique, with composite resin repairs being the easiest and Zirconia-based repairs the most challenging. This method helps deliver quick and satisfying results, enhancing the longevity and aesthetics of fixed porcelain dentures.

A Comparative Evaluation of Prosthetic and Biological Outcome as Influenced by Two Different Implant Restorative Materials (Porcelain Fused to Metal and Monolith Zirconia): A Prospective, Cross-arch Study.

To investigate the prosthetic parameters, clinical indices, crestal bone levels, and inflammatory biomarkers in peri-implant crevicular fluid as influenced by two different implant restorative materials i.e., metal ceramic and monolithic zirconia at baseline, 1 Year and 2 Years. Twenty patients with bilateral implants placed in the same arch were selected. Monolithic zirconia (4Y-PSZ) crown was placed on one side whereas a metal ceramic (M C) crown was inserted on the contralateral side after randomization. Interproximal marginal bone level (MBL), clinical parameters, MMP-8 levels in PICF, and prosthetic characteristics (as determined by modified USPHS criteria) were evaluated at baseline, 1-year, and 2-year follow-ups. Data were descriptively examined. The results were evaluated using the Chi-Square Test, ANOVA, and student t-test. At p < .05., statistical significance was determined. Twenty MC crowns and twenty Mono-ZrO2 crowns were delivered. A 100% survival of the implants and the prosthetic crowns was achieved across all patients with no instances of failure noted throughout the two-year follow-up period. The periodontal changes observed in the participants were analysed and demonstrated statistically insignificant alterations. Prosthetic alterations were assessed according to USPHS criteria, revealing minor ceramic chippings and instances of screw loosening within the MC group during both the 1- and 2-year follow-up periods. These incidents were collectively categorized as technical issues. Regarding anatomical form and color match to the surrounding dentition, the Mono- ZrO2 crowns obtained much lower evaluations when compared to the M-C crowns. However, when evaluating the loss of marginal bone and level of inflammatory markers there were no discernible variations between the groups. The null hypothesis that there is no similarity in the survival rates and interactions at the peri-implant interface between the two types of restorations was rejected. Both monolithic zirconia and metal ceramic crowns demonstrated no statistical differences across all parameters examined in the present prospective investigation.

Evaluation of Patient’s Aesthetic Satisfaction after the Cementation of the Porcelain Fused to Metal Crown

Aim: To assess the aesthetic satisfaction with the metal-ceramic dental prosthesis in relation to patient education, age and gender. Methods: This prospective longitudinal study was undertaken by selecting 360 adult patients from both genders indicated for single maxillary porcelain fused to metal crowns. These patients were categorized into three groups based on gender, age, and education. Patients were assessed for aesthetic satisfaction for tooth shape; color, angulation, visibility, and shade at the time of insertion and at a follow-up of 12 weeks. At the time of the prosthesis insertion, a self-evaluation questionnaire was provided to each patient to record their satisfaction levels with the prosthesis. Satisfaction levels among the participants were evaluated based on participants' age, gender, and education level (Chi-square). A p-value of 0.05 was considered statistically significant. Results: The study enrolled 150(41.67%) males and 210(58.33%) females with the participant age ranging from 19 to 60 years and a mean age of 30.53 (± 10.88 years). 84(23.3%) were uneducated participants, 210(58.3%) were high school graduates, and 66(18.3%) were university graduates. A decrease in the level of satisfaction was observed with increasing years of patient education at insertion. The overall aesthetic satisfaction among patients at PFM crown insertion (65%) and at 12 weeks follow-up (69.2%) was statistically comparable (p&gt;0.05). Practical implication: Aesthetic is the most important consideration for the replacement of anterior teeth. Numerous studies evaluated the aesthetic satisfaction of the patients after providing full ceramic prosthesis, however, data regarding patient satisfaction after the metal ceramic dental prosthesisis scarce in the scientific literature. Conclusion: Satisfaction with the esthetic restoration depends on patient education and awareness. Age and education add to a person's experience and increase awareness with respect to better aesthetics. Keywords: Aesthetics; patient satisfaction; assessment; patient care, metal ceramic prosthesis

Bond Strength of Porcelain Fused to Casting and Selective Laser Base Metal Alloy with a Bonding Agent

Purpose: The goal of this study was to assess how different bonding agents affected the shear bond strength of a feldspathic ceramic fused with a cobalt-chromium alloy that was manufactured using two different techniques: lost wax and a 3D printer. Approach: A total of 40 disks of the cobalt-chromium alloy were made by using casting (Co–Cr) as the control group (n=20 specimens) and additive manufacture by selective laser melting. SLM from Co–Cr (n=20 specimens) the disks were airborne particles abraded with110 µm aluminum oxide particles, then two main groups separated into subgroups based on the type of bonding agent used (with and without addition). shear bond strength was used, before the SBS test the metal and ceramic interfaces were examined using test scanning electron microscopy (SEM). The elemental makeup of the bonding agents was determined using an energy-dispersive X-ray spectroscopy (EDS) test. The results of the SBS tests as well as the failure modes were noted. Data were analyzed using the Least Significant Difference (LSD) test (a = 0.05). Result: Bond strength was much stronger in Co-Cr specimens with bonding agents than in Co-Cr specimens without bonding agents. The mass quantities of silicon (Si) and some titanium (Ti) on the surfaces of alloys varied depending on the production method and the presence of a bonding agent. Conclusion: By use of a bonding agent on various Co-Cr metals improves bond strength with ceramics.

Comparative Evaluation of Surface Roughness of Porcelain Fused to Metal and Stainless-Steel Crown Following Ultrasonic and Hand Scaling: A Comparative Study.

IntroductionSurface roughness encourages plaque retention and causes mechanical, chemical, and biological irritation to surrounding soft tissues. Hence, a smooth surface of restoration is preferred for optimal plaque control and the health of the periodontium.AimThe aim is to evaluate and compare the surface roughness of porcelain fused to metal and stainless-steel crowns following ultrasonic and hand scaling techniques.Material and methodsAn in-vitro study was conducted on 30 porcelain fused to metal crowns and 30 stainless-steel crowns. Their surface roughness following instrumentation was evaluated by scanning electron microscope (SEM) and profilometry.ResultsEvaluation by profilometry indicated that porcelain fused to metal following ultrasonic instrumentation has a statistically more significant surface roughness and indentation as compared to hand scaling with p-values < 0.05.ConclusionThe surface roughness of any restoration may act as a plaque retentive factor which would affect the health of the periodontium. Ultrasonic scaling is capable of creating roughness to a more extent as compared to hand scaling and porcelain fused to the metal type of restorations is more vulnerable to roughness.

Distinctive analysis of the shear bond strength of Porcelain Fused Metal substructure fabricated by conventional casting, direct metal Laser Sintering and CAD-CAM processing techniques

Background:The use of metal-ceramic restorations began in the late 1950’s allowing the development of prosthetic rehabilitation with better cosmetic results replacing previously in-demand precious metals. These restorations are commonly preparedusing conventional casting, Direct Metal Laser Sintering and CAD-CAM processing techniques. The present study has been attempted to perform a distinctive analysis of the shear bond strength of porcelain fused metal substructure fabricated by conventional casting, Direct Metal Laser Sintering and CAD-CAM processing techniques. Materials and Methods: The present study follows an in-vitro study design. A total of 45 samples were prepared and divided into 3 groups (n=15 in each group): conventional casting, Direct Metal Laser Sintering and CAD-CAM groups. The shear bond strength of all the specimens was measured using Universal Testing Machine. The specimens were subjected to shear load at the metal-porcelain interface with increasing load and the crosshead speed of 2 mm/sec till the disc debonded completely. The debonded samples were observed under Scanning Electron Microscope to assess the kind of failure. Results:The obtained data of three experimental group samples were analysed using the student’s t-test, One-way ANOVA test and Tukey’s Post-hoc test. Results of t-test showed that, of all the three techniques, Casting technique showshighest mean of force and shear bond strength, and this mean difference was significant. The same results were shown in One-way ANOVA test and Tukey’s Post-hoc test. Conclusion: From the observations of the present study, it can be stated that Casting technique showed highest mean of load and shear bond strength followed by the CAD/CAM method and DMLS technique, respectively. The results of this study ranged from 69-87MPa which is within the safety borders. Therefore, it can be concluded that allthree methods can be used to fabricate the metal substructure in metal-ceramic restoration.

One Year Clinical Evaluation of Milled BioHPP Polyetheretherketone (PEEK)-Based versus Metal Ceramic Single Crowns (Randomized Controlled Clinical Trial)

Objective: To evaluate the clinical behavior of milled BioHPP PEEK copings veneered with Visio.lign composite resin in comparison with metal copings veneered with feldspathic porcelain as single posterior crowns. Material and Methods: Twenty Four full coverage posterior crowns were fabricated for endodontically treated molars divided into 2 groups according to the material used. Twelve milled BioHPP PEEK-based crowns (Group 1) and Twelve Porcelain Fused to Metal (PFM) crowns (Group 2). The preparations were standardized with an equi-gingival, deep chamfer finish line for all teeth. BioHPP PEEK and metal copings were fabricated by CAD/CAM technology and lost wax technique respectively. These coping were veneered according to manufactures instructions either by special composite resin or low fusing glass ceramic respectively. The restorations were cemented then clinical evaluation of these crowns was assessed regarding mechanical failure, marginal integrity and patient satisfaction every two months for one year. Results: Although two PEEK crowns were fractured, both PEEK and PFM crowns showed similar fracture (mechanical failure) and marginal integrity without significant difference (P &gt; 0.05). BioHPP PEEK-based crowns showed statistically significantly lower patient satisfaction than PFM crowns after six months (P-value = 0.013, Effect size = 1.157) but all the patients were generally satisfied. Conclusion: BioHPP PEEK-based crowns showed clinically similar and accepted mechanical behavior and marginal integrity but less patient’s satisfaction than PFM crowns after six months. So BioHPP PEEK-based crowns may be used as an alternative tooth-colored metal-free fixed restoration for one year. Keywords BioHPP; Metal ceramic; Patient satisfaction; PEEK; PFM.

Technical Accuracy of Dental Laboratories in the Quality and Shade Matching of Porcelain Fused to Metal Crowns: An In Vitro Study.

Dental laboratories (LABs) are integral to the performance of a dentist in providing successful oral rehabilitation. The aim of this study was to compare the adaptation, contour, contacts, and shade matching of different government and commercial dental LABs in the fabrication of porcelain fused to metal (PFM) crowns. Thirty-two dental LABs were selected to fabricate PFM crowns (one PFM crown each). Marginal adaptation, contour, proximal contacts, and shade matching were evaluated. Evaluation of the crowns’ quality was performed following modified USPHS/FDI criteria. Visual and colorimeter assessments were employed to evaluate shade matching. Differences between groups were examined by Pearson’s Chi-square and Fisher’s exact test. The quality of marginal adaptation of crowns was good in 81.25%, however the quality of contours, contacts, and shade matching was compromised in 43.75%, 59.38%, and 39% of all LABs, respectively. Visual and colorimeter shade matching was acceptable in 62.5% and 80% of LABs in the cervical third and middle third regions of crowns, respectively, however in the incisal third the shade matching was unacceptable in nearly 60% of LABs. Commercial laboratories showed significantly better contours and shade matching, but not marginal adaptation. However, no significant differences were found in comparison of proximal contacts between the groups.

Finite Element Analysis of effect of cusp inclination and occlusal contacts in PFM and PEEK implant-supported crowns on resultant stresses

BackgroundEffect of prosthesis design on occlusal overload and long-term implant stability cannot be overstated. In Porcelain Fused to Metal (PFM) crowns, low cusp inclination and occlusal contacts limited to central fossa ensure axially directed forces on an implant but often pose esthetic and functional challenges. It is theorized that resilient Polyetheretherketone (PEEK) crowns have shock absorption capacity for favorable stress distribution. This study compared two implant crown materials and evaluated the effect of cusp inclination and occlusal contact distribution on resultant stresses. MethodsThirty 3D finite element models of implant-supported PFM and PEEK crowns, generated using Solidedge 3D CAD solid modeling software (v19, Siemens PLM Software Inc.,US), were used to study the effect of 3 cups inclinations (0°, 15°, 30°) under five load conditions, with 300N force distributed over one, two, or three contact areas and exported to ANSYS (v18.1, ANSYS Inc. Pennsylvania, US) for stress analysis. ResultsMaximum stress in both PFM and PEEK models was at the neck of the implant under Load 3(300N distributed over three contact areas: central fossa, buccal cusp tip, marginal ridge). Minimum stress in all models was under Load 1(300N applied at one contact area in central fossa). Maximum stresses were recorded for 30° cusp inclination in PFM models. ConclusionIn both PFM and PEEK crown models, contact areas placed away from the implant axis generated greater implant and peri-implant stresses and had more effect on resultant stresses than that of increase in cusp inclination. The effect of cusp inclination on the resultant stresses was dependent on the crown material.

A Scanning Electron Microscopy and Energy Diffraction X-Ray Spectroscopy Study to Evaluate the Effect of Firing Temperature at the Ceramic-Noble Metal Alloy Interface in Porcelain Fused to Metal Restorations

Introduction: Porcelain Fused to Metal (PFM) restorations offer aesthetics of ceramics and the strength of metal hence are the gold standards of fixed partial dentures. However, the fracture of porcelain-metal interface still remains a matter of concern. Aim: To study the porcelain-noble metal alloy interface of PFM restorations at different firing temperatures, using Scanning Electron Microscopy (SEM) and Energy Diffraction X-ray Spectroscopy (EDS). Materials and Methods: This in-vitro study was conducted between November 2018 to October 2019 at Prosthodontics Department of Saraswati Dental College and Hospital and King George’s Medical University Lucknow, Uttar Pradesh, India. A total of 75 strips of noble metal alloy were prepared and layered with 1 mm of porcelain on one surface, conforming to American National Standard/American Dental Association Specifications (ANSI/ADA) specification no. 38 for Metal-Ceramic Dental Restorative Systems: 2015. These were randomly divided equally into three groups. Specimens of each group (n=25) were fired at different temperatures that is 850oC, 900oC and 960oC, respectively. Scanning electron microscopy and Energy diffraction X-ray spectroscopy were performed at the noble metal alloy and ceramic interface of all specimens. Data was recorded and statistically analysed using one-way Analysis of Variance (ANOVA) and post-hoc Tukey HSD test. Results: Irregularities/Coarseness (50 μm) was seen on the noble metal alloy surface adjacent to ceramic layer in SEM images at all the three chosen temperatures. The EDS study revealed intermingled zones of partial oxygen depletion at the interface region with formation of intermetallic compound, lead zirconate titanate and complete oxygen depletion zone near metal alloy end of interface. The mean value of Shear Bond Strength (SBS) was 16.31 MPa at 850oC, 24.33 MPa at 900oC and 19.41 MPa at 960oC (p-value &lt;0.05). Conclusion: Difference in properties and location of the intermetallic compound formed at the interface, as well as the location of the oxygen depletion zone could account for the weaker bond formed between noble alloy-porcelain interface compared to base metal-porcelain interface.

Comparative Evaluation of Porcelain Fused to Metal (PFM) Material used for Fixed Partial Prosthesis Placed on Vital &amp; Non-vital Abutments on the Periodontal Status – A Two Year Retrospective Follow-up

Objective: Sound periodontal foundation of abutment teeth is essential for successful restorative therapy and also for long-term success of prosthodontic restorations. Porcelain fused to metal (PFM) has been a popular choice of novel esthetic material in fixed prosthodontics over the last few decades. The present study aimed to assess the long term effect and tissue responses of fixed partial prosthesis using PFM material on vital and non- vital abutments on the periodontal parameters both clinically and radiographically.&#x0D; Methodology: Following ethical committee approval, the study group comprised of 86 abutment teeth in 41 systemically healthy patients (24 males and 17 females) aged between 18 – 45 years who had received 3 unit fixed prosthesis made of PFM, having equigingival margins using vital and non-vital abutments. The following parameters were assessed at baseline, phase 1, 3 and 4 (1 year follow up) – CAL, Probing depth, Distance between CEJ/ cervical crown margin and alveolar crest of the abutment teeth (radiograph).&#x0D; Results: Statistical analysis carried out by SPSSV22 software revealed no significant changes in probing depth and CAL (p&gt;0.05) and significant changes in radiographic bone levels (p&lt;0.05) in vital abutments whereas significant changes in probing depth and CAL from baseline to the end of 2 years (p&lt;0.05) with no changes in radiographic parameters (p&gt;0.05) with non vital abutments. However, significant differences were observed between vital and non vital abutments with regard to probing depth at the end of 2years, CAL and radiographic bone levels at 6months, 1 year and 2 years (p&lt;0.05)&#x0D; Conclusion: The response of the periodontal tissues to the PFM material used on fixed prosthesis on both vital and non vital abutment teeth although favorable, were marginally better in vital abutments.

In Vitro Comparison of Porcelain Fused to Metal Crown Retention after Endodontic Access and Subsequent Restoration: Composite, Amalgam, Amalgam with Composite Veneer, and Fiber Post with Composite

IntroductionThe aim of this study was to evaluate the effect of different access opening restorative materials on crown retention. MethodsThirty-eight extracted molars were mounted in resin and prepared for porcelain fused to metal (PFM) crowns. The crowns were fabricated and cemented with zinc phosphate, and the force to displace it was measured with a tensile-testing machine before and after endodontic access preparations. The endodontic access area, crown preparation axial wall, and preparation surface area were measured for comparison. The crowns were then recemented, and access openings were restored with either amalgam or composite before displacement force was remeasured. The restorative material was removed from each access opening; access area was measured and restored again (amalgam with composite or fiber post with composite) for displacement force to be remeasured. Paired t test was used to compare the means of displacement between groups. One-way analysis of variance was used to compare the mean outcome measure within the groups. ResultsStatistical analyses showed retention after unfilled access was significantly lower than intact crowns. Amalgam, composite, amalgam + composite, and fiber post + composite increased retention beyond the original value. There was no statistical difference among the different restorative protocols. Qualitative results indicate that the restorative material remains in the crown after displacement regardless of the material used to restore the access. ConclusionsThe results from this study suggest that an endodontic access cavity decreases retention of a PFM crown. However, subsequent restoration with amalgam, composite, amalgam + composite, or post + composite may increase the original retention of the crown.

Effect of core materials for core fabrication for dental implants on in-vitro cytocompatibility of MC3T3-E1 cells

BackgroundDespite the wide use of dental materials for CAD/CAM system in prosthetic treatment, the effect of the materials, which are used as dental implants core fabricated, on cells involved in dental implant osseointegration is uncertain. This study aimed to investigate and compare the effect of single core materials used for dental implants fabricated by the dental prostheses fabrication process and the CAD/CAM milling method on MC3T3-E1 cells.MethodsThe materials used for prostheses restoration in this experiment were Porcelain Fused Gold (P.F.G), Lithium disilicate glass ceramic (LiSi2), Zirconia (ZrO2), Nickel-Chromium (Ni-Cr) and Cobalt-Chromium (Co-Cr). MC3T3-E1 cells were cultured and used, the cell adhesion and morphology were observed and analyzed using confocal laser scanning microscopy (CLSM). Methoxyphenyl tetrazolium salt (MTS) and alkaline phosphatase (ALP) assay were used to observe the cell proliferation and differentiation.ResultsCLSM revealed irregular cell adhesion and morphology and the filopodia did not spread in the Ni-Cr specimen group. Significantly high cell proliferation was observed in the ZrO2 specimen group. The LiSi2 specimen group presented significantly high cell differentiation. Intergroup comparison of cell proliferation and differentiation between the Ni-Cr specimen group and all other specimen groups showed significant differences (p < .05).ConclusionCell proliferation and differentiation were observed from the cores, which were fabricated with all specimen groups on cytocompatibility except the Ni-Cr specimen group.

A Comparative Evaluation of Shear Bond Strength of Orthodontic Brackets Bonded to Porcelain Fused Metal Crowns Treated with Different Surface Conditioning Techniques―An Invitro Study

With the increase in adult orthodontic treatment comes the need to find a reliable method for bonding orthodontic brackets onto metal or ceramic crowns and fixed partial dentures. In this study, shear bond strength and surface roughness tests by scanning electron microscope study were used to examine the effect of 5 different surface conditioning methods: 37% phosphoric acid gel, 9% Hydrofluoric acid, sandblasting + 9% Hydrofluoric acid, Sandblasting + Silane, Fine diamond bur roughening + silane for bonding metal brackets to ceramic surfaces of feldspathic porcelain. A total of 60 human maxillary premolar teeth extracted for therapeutic purposes from patients seeking orthodontic treatment were collected, and 50 ceramic crowns were fabricated onto the premolar teeth following crown preparation. 10 natural teeth were used as controls, they were acid etched in conventional manner using 37% phosphoric acid. Metal brackets were bonded using a light-curing composite. The samples were stored in distilled water at physiological temperature (37oC) for 1 day, and thermocycled 500 times between 5°C and 55°C. Shear bond tests were performed with a universal testing device, and the results were statistically analysed. Ceramic surfaces conditioned with sand blasting followed by application of Silane produced maximum bond strength of 12.34 ± 0.95 MPa comparable or even better than the control group 11.03 ± 1.63 MPa followed by 9% Hydrofluoric acid 11.48 ± 0.98 MPa & Fine Diamond Bur roughening + Silane 9.28 ± 1.11 MPa. Ceramic surfaces conditioned with 37% Ortho Phosphoric acid produced least SBS of 5.51 ± 0.88 MPa and hence not suitable for bonding Orthodontic brackets in a clinical scenario. Statistical tests showed significant difference between and within the groups in shear bond strength and P value also was highly significant, i.e. ***p<0.001. The SEM photomicrographs of all the six different surface preparations revealed different surface morphologies & were corroborative of SBS values. Even though 9% Hydrofluoric acid and Fine diamond bur roughening produced clinically acceptable SBS values, because of their technique sensitivity and side effects, they have to be used with great care and caution. sand blasting followed by the application of Silane coupling agent was found to be the best porcelain surface conditioning method.

Assessment of Fracture Resistance Capacity of Different Core Materials with Porcelain Fused to Metal Crown: An in vitro Study

Aim: The aim of the study was to evaluate the capacity to resist fracture in different core buildup materials with porcelain fused to metal (PFM) crown. Materials and methods: Totally, 45 mandibular single rooted first premolars were collected, which were sound along with similar shape and size. The teeth were sectioned at 15 mm above the root apex sparing the sound tooth structure. The teeth were endodontically treated with the crown-down technique using nickel-titanium (NiTi) instrumentation. The specimens were randomized into three groups as per the core materials used and were labeled accordingly. Group I consisted of dual-cured composite resin, group II consisted of glass ionomer reinforced with resin, and group III consisted of Miracle mix. Universal loading machine is used for measuring the compres-sive load applied to fracture the tooth. Results: The mean value of compressive strength was maximum in the dual cured composite resin (598.42 ± 22.64) followed by glass ionomer reinforced with resin (478.88 ± 26.74) and Miracle mix (442.16 ± 30.10). The results showed a significant difference statistically within the core materials used with p < 0.05. The results from the Tukey's post hoc test of multiple comparisons between dual-cured composite resin vs glass ionomer reinforced with resin, dual-cured composite resin vs Miracle mix, and glass ionomer reinforced with resin vs Miracle mix showed a highly statistical difference with p < 0.05, which is significant. Conclusion: This in vitro study showed that the dual-cured composite resin had maximum resistance to fracture compared with other core buildup materials on teeth which were endodonti-cally treated. Clinical significance: Restoration of a tooth which is structurally compromised is a tricky job for all the dentists. Restoring it with a proper core buildup material with adequate fracture resistance makes the tooth structure stable. The core material should be able to resist all types of occlusal forces and to distribute it equally within the tooth structure. Keywords: Core buildup, Crowns, Endodontically treated teeth, Fracture resistance.

In Vitro Comparison of Marginal Fit of All Metal, Porcelain Fused to Metal and All Ceramic Crowns

PURPOSE: To compare the marginal fit of all metal, porcelain fused to metal and all ceramic crowns fabricated using different materials and techniques commercially available. MATERIALS AND METHODS: 80 freshly extracted human mandibular first premolars were divided into 8 groups of 10 each which received Nickel-Chromium (Ni-Cr) all metal (AM) crowns, Cobalt-Chromium (Co-Cr) AM crowns, Ni-Cr three-quarter crowns, Co-Cr three quarter crowns, porcelain fused to metal (PFM) crowns with Ni-Cr copings, PFM crowns with Co-Cr copings, pressed all ceramic (AC) crowns and CAD/CAM fabricated AC crowns respectively. Crowns were cemented and specimen were sectioned buccolingually. The marginal gap was evaluated under a stereomicroscope. Lesser marginal gap indicated a better marginal fit. RESULTS: The mean marginal gap was maximum for Group 8 (222.3 μm) and least for Group 1 (85.5 μm). The mean marginal gaps for ‘all metal crowns’ and ‘metal ceramic crowns’ showed significantly lesser marginal gaps (p&lt;0.05) for Ni-Cr Groups than Co-Cr Groups. When only ‘all ceramic crowns’ were compared, significantly lesser marginal gap was found for pressed AC crowns (148.6 μm) than CAD/CAM fabricated AC crowns (222.3 μm). CONCLUSION: Marginal fit of AM crowns were significantly better than PFM crowns and AC crowns. Ni-Cr group always showed better marginal fit than Co-Cr group. A better marginal fit of pressed AC crowns was seen than CAD/CAM fabricated AC crowns. Chamfer finish line showed a significantly better marginal fit than shoulder finish line.

An In-vitro Comparative Stereomicroscopic Analysis and Evaluation of Marginal Accuracy in Porcelain Fused to Metal Copings Fabricated in Two Different Finish Lines Using Variant Die Materials

Limited published information is available about the influence of preparatory designs and die materials on marginal accuracy of porcelain fused to metal copings using recently developed die materials. To detect the influence of margin geometries and dimensional accuracy of contemporary die materials on vertical marginal gaps in Porcelain fused to metal coping using a Stereomicroscope (three dimensional analysis). Two chrome cobalt alloy models of mandibular first molars prepared to have shoulder and deep chamfer finish lines were CAD-CAM milled. Elastomeric impressions of these models were made in a custom tray, poured in Type IV Gypsum(n=10) and Resin modified Gypsum(n=10) and also packed with Epoxy resin (n=10) as a die material to form a total of 60 samples, 30 in each group (shoulder and deep chamfer). Wax patterns were fabricated, invested and castings in ceramic alloy were obtained in traditional manner. These copings were later analyzed on CAD/CAM models using stereomicroscope. Both the designs did not exhibit significant difference (p<0.05). Whereas, the three die materials exhibited significant difference (p<0.05) by Two way ANOVA test and Tukey's multiple Post Hoc test. Results from this study showed that vertical marginal gaps for copings fabricated on resin modified gypsum as a die material were within the clinically acceptable range. Margin geometries both shoulder and deep chamfer have equal influence on vertical marginal gaps in metal ceramic restorations. Copings fabricated on Epoxy resin dies exhibited highest value of vertical marginal discrepancy, where as least value was determined for copings constructed on dies fabricated from resin modified gypsum.

An Overview of the Current Survival Status and Clinical Recommendation for Porcelain Fused to Metal vs All-ceramic Zirconia Posterior Fixed Partial Dentures

ABSTRACT Porcelain fused to metal (PFM) restorations has shown promising results in terms of longevity over decades. However, due to the paradigm shift with the preferences of both the patients and clinicians toward all ceramic restorations, these prostheses are being increasingly used in posterior region. Zirconia is one of the popular materials in dentistry today; it has good mechanical strength and has shown remarkable results in shortterm studies from 3 to 5 years. However, zirconia aging and chipping are most common causes of zirconia failure, besides loss of retention has also been reported in some studies. Nonetheless, there are no substantial studies that decipher the longevity of these restorations over a longer period of time. Moreover, it has been reported that zirconia cannot be used in areas of higher stresses. This review article compares the promising ceramic material zirconia and PFM restorations in terms of longevity and esthetics based on the present studies. An electronic search was conducted across Ovid Medline, complemented by manual search across individual databases, such as Cochrane and Google Scholar for literature analysis on PFM restorations, zirconia crowns, and fixed partial dentures (FPDs). The studies were reviewed and results were compared for the same. This paper summarizes the current scientific and clinical opinion through a brief review regarding the preferred material for posterior crowns and FPDs. It denotes that case selection and certain other factors can play a role in success of the zirconia prosthesis. How to cite this article Vijan KV. An Overview of the Current Survival Status and Clinical Recommendation for Porcelain Fused to Metal vs All-ceramic Zirconia Posterior Fixed Partial Dentures. World J Dent 2017;8(2):145-150.

치과 도재용착용 Ni-Cr 합금의 열처리에 따른 결합력 연구

치과 도재용착용 Ni-Cr 합금의 열처리에 따른 결합력 연구

Assessment of Porcelain Fused to Metal Crown Preparations by General Practitioners in Saudi Arabia

Background: Principles for fabricating prosthetic restorations include sufficient axial preparation and adequate occlusal clearance of the prepared teeth. This study measured the convergence angles in the prepared teeth for porcelain fused to metal (PFM) crowns done b y general practitioners in different regions of Saudi Arabia. In addition, the presence of planar occlusal reductions, functional cusp bevels and rounded angles in prepared casts were evaluated. Original Research Article