Removable Partial Denture Frameworks Research Articles

Suitability and Trueness of the Removable Partial Denture Framework Fabricating by Polyether Ether Ketone with CAD-CAM Technology.

The object of the study was to evaluate the suitability and trueness of the removable partial denture (RPD) framework fabricated by polyether ether ketone (PEEK) with the CAD-CAM technology in vitro. Four different types of dentition defects were selected. In each type, five PEEK RPD frameworks were fabricated by the CAD-CAM technology, while five Co-Cr RPD frameworks were made by traditional casting. The suitability of the framework was evaluated by silicone rubber film slice measurement and the three-dimensional image overlay method. The trueness of the PEEK framework was detected by the three-dimensional image overlay method. Data were statistically analyzed with the use of an independent samples t-test (α = 0.05). The suitability values by silicone rubber film slice measurement of the PEEK group were lower than those of the Co-Cr group in four types, with the differences indicating statistical significance (p < 0.05) in type one, type two, and type four. The suitability values using the three-dimensional image overlay method showed no statistical differences (p > 0.05) between the two groups in four types. The trueness values of the PEEK group were within the allowable range of clinical error. The suitability and trueness of the PEEK RPD framework fabricated by CAD-CAM technology met the requirements of the clinical prosthesis.

A digital workflow for designing and manufacturing metal frameworks and removable partial dentures: A novel dental technique.

The purpose of this technical report is to demonstrate a fully digital workflow for designing and fabricating metal frameworks and removable partial dentures. After obtaining a digital cast of the dental arch with bilateral distal extension defect, computer-aided design software and 3D printing technology are used for the design and fabrication of the removable partial denture frameworks, denture teeth, and denture bases, instead of the traditional workflow. The assembly of the three components is facilitated through a meticulously structured framework. The technology, which prints metal frameworks, denture bases, and denture teeth through different processes with different materials, achieves full 3D printing technology for making removable partial dentures.

Fit Accuracy of Cobalt–Chromium and Polyether Ether Ketone Prosthetic Frameworks Produced Using Digital Techniques: In Vitro Pilot Study

This pilot study aimed to compare the fit accuracy of cobalt–chromium (Co-Cr) and polyether ether ketone (PEEK) removable partial denture frameworks, produced by digital technologies. Two study models of previously prepared Kennedy’s Class I and Class III mandibular dental arches were scanned. For each model, two frameworks were digitally designed and manufactured using a Co-Cr alloy via the selective laser melting (SLM) technique, and using PEEK via the milling technique. A qualitative assessment of the framework’s fit accuracy to the corresponding study models was carried out using calibrated endodontic instruments and image amplification. Best-fit superimpositions between the reference design and the scanned frameworks were performed using the Geomagic Control X version 2018, 3D Systems software, allowing the expression of trueness by calculating the root mean square (RMS) value. Higher fit accuracy was observed for the milled frameworks, with the Class I PEEK framework showing the best fit accuracy to the corresponding model. RMS values were Class I—148.3 μm for Co-Cr and 69.2 μm for PEEK; Class III—107.2 μm for Co-Cr and 59.7 μm for PEEK. In the experimental conditions used, the milled PEEK frameworks showed better fit accuracy and higher trueness than the SLM-printed Co-Cr ones in both Kennedy classes.

A Preliminary Study on the Accuracy of Cast Metal Removable Partial Denture Frameworks Produced from Wax, Printed, and Milled Patterns

To compare the accuracy of two digital workflows for producing resin patterns to be cast into metal frameworks compared to an identical framework manufactured conventionally from a wax pattern. Nine casts were duplicated from a maxillary master cast of a partially edentulous arch. Their accuracy was determined by measuring the same points in two and three dimensions using a reflex microscope, which was also used to measure all frameworks to an accuracy of 4 μm. The same design was used throughout. Three casts were used to make a framework conventionally from an invested wax pattern. Six casts were scanned, and a digital pattern created. Three patterns were milled from a resin block, and three were 3D printed with resin. Then each pattern was cast. The sample size precluded direct statistical conclusions, but no significant differences were found. Duplicate models showed minimal differences compared to the master cast. All patterns and all frameworks showed some level of difference compared to the master cast, but no differences were greater than those reported in the literature as being clinically acceptable. The maximum overall discrepancy between the cast frameworks was 0.64 mm, and at the rest seats was 0.262 mm. Within the limitations of this study, given the very small actual differences both within and between the groups of the three different workflows, the use of digitally produced resin patterns prior to their being cast as metal frameworks is both feasible and well within the accepted limits for clinical acceptability.

The Dimensional Changes of Clasp Arm in Removable Partial Denture Frameworks Fabricated Through DMLS and Conventional Lost Wax Technique: An In Vitro Study

AIM: The aim of the present study is to evaluate the effect of CAD designing on the dimensions of the clasp arm. METHODOLOGY: A Kennedy Class III mod I cast was selected as the reference cast. Samples were divided into 2 groups, Group I with DMLS and Group II with Conventional lost wax technique. Three reference points were selected on the clasp arm and the vertical dimensions were measured in the digital design and compared it with the dimensions at the same points in the final framework. RESULTS: There was slight expansion in group 1 (p-value &gt; 0.05) with mean of -0.035 and standard deviation 0.088. And there was decrease in dimensions in the clasp arm in group 2 (p-value &lt; 0.05) with mean of 0.1741 and standard deviation 0.081. CONCLUSION: From the present study, it was concluded that the dimensions of the clasp arm of DMLS framework increased slightly, whereas the there was significant decrease in the clasp arm dimensions in the framework produced through conventional lost wax technique. Both the frameworks had clinically acceptable fit.

Comparative analysis of the retention force and deformation of PEEK and PEKK removable partial denture clasps with different thicknesses and undercut depths

Statement of problemThe retentive force and deformation of milled polyetheretherketone (PEEK) and polyetherketoneketone (PEKK) removable partial denture (RPD) frameworks are not well understood. PurposeThe purpose of this in vitro study was to assess the retentive force and deformation of PEEK and PEKK Akers clasps with different designs and undercut depths. Material and methodsA master model containing the first and second molar abutments was used to design Akers clasps of different cross-sectional dimensions, undercut depths (0.5 and 0.75 mm), and materials. The components of the removable partial denture framework also included an occlusal rest and were manufactured using a milling machine (n=5). The fatigue resistance of the Akers clasps was measured before and after deformation regarding the retentive forces. ResultsThe PEEK2-U50 clasp had the largest retentive force with no significant difference among all groups before and after the insertion and removal cycle. In addition, the increased cross-sectional dimensions of the design resulted in significant differences in retentive forces between the PEEK1 and PEEK2 groups and between the PEEK and PEKK materials. ConclusionsIncreasing the clasp's cross-sectional dimensions significantly impacted retentive forces, especially between different PEEK groups and between PEEK and PEKK materials.

Patient-reported outcomes and framework fit accuracy of removable partial dentures fabricated using digital techniques: A systematic review and meta-analysis.

This review aimed to summarize the evidence on patient-reported outcomes and clinical performance of digitally fabricated removable partial dentures (RPDs) compared to traditionally fabricated dentures. Three databases were systematically searched (PubMed, CENTRAL, and Wiley online library) for clinical studies comparing digitally and conventionally fabricated RPDs regardless of data acquisition methods used for fabrication. The Cochrane Collaboration risk of bias assessment tool 2 and the Oxford Center for Evidence-based Medicine tool were used to assess risk of bias, and level of evidence, respectively. Descriptive narrative analysis was used to summarize data on patient-reported outcomes, as there were inadequate studies to pool data in a meta-analysis. A random-effects model was used to analyze the data of framework fit accuracy. Ten randomized controlled trials were included in the systematic review, and 4 were included in the meta-analysis. Two studies showed that digitally fabricated RPDs are associated with higher patient satisfaction than conventionally fabricated RPDs (with a mean difference of 12.5mm on a 100-satisfaction scale, p = .008). The pooled standardized mean difference for framework fit accuracy was 0.49 (p = 0.02) in favor of conventionally fabricated RPDs, which showed that conventionally fabricated RPDs have a quantitatively better fit compared to digitally fabricated RPDs. However, clinical evaluation studies showed that both frameworks have clinically acceptable fit. Current evidence shows that digitally fabricated RPDs are associated with higher patient satisfaction compared to conventionally fabricated RPDs. However, the scarcity of literature here warrants the generalization of this conclusion. Both digitally and conventionally fabricated metal RPD frameworks showed acceptable fit clinically.

Which metal surface treatment improves the bond strength between metal alloys and acrylic resin in removable partial dentures? A systematic review.

The union of the metal removable partial denture framework to the heat polymerized acrylic resin is related to prosthesis longevity. However, methods to enhance this bond are not clear to clinicians and dental laboratory technicians. The purpose of this systematic review was to identify which metal surface treatments best increase the bond strength between heat polymerized acrylic resin and removable partial denture alloys. This review was carried out following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and registered in the International Prospective Registry of Systematic Reviews (PROSPERO) database (CRD42022384926). Electronic searches were carried out independently, by 3 examiners in Medline/PubMed, Scopus, and Web of Science databases, and in the nonpeer-reviewed literature via ProQuest. The electronic searches resulted in 4143 articles, with 4055 after removing duplicates. After reading the titles and abstracts, 37 articles were selected for reading in full-text version, from which 6 articles were included. All studies evaluated materials for conventional acrylic resin denture base (heat polymerized), processed by water bath, bonded to metal. For the metal framework alloys, cobalt chromium (Co-Cr) alloys were used in 2 studies, titanium (Ti) in 2 studies, and Co-Cr and Ti in the other 2 studies. Different metal surface treatments were used as airborne-particle abrasion with aluminum oxide (particle sizes of 50µm, 110µm, and 250µm) followed by the primer application and the isolated use of the primer, compared to the absence of isolated intervention or airborne-particle abrasion of the metal surface. Among the different primers used, those based on 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) showed the highest acrylic resin-to-metal bond strength values. Airborne-particle abrading the metal with Al2O3 followed by applying a 10-MDP-based primer, increased the bond strength between metal framework alloys and heat polymerized acrylic resin denture base material.

An Experimental Method to Add New Prosthetic Teeth in the Removable Partial Denture Framework: TIG Cold Welding and Preformed Pins

The need to modify removable partial dentures equipped with a metal framework in order to add other prosthetic teeth to replace natural teeth lost by the patient could lead to laboratory procedures so complex as to require the creation of new prostheses with a heavy economic burden. The creation of preformed metal pins to be welded using the economical TIG cold welding method could represent a valid alternative solution with the aim of modifying the prostheses using a reinforced resin capable of adequately resisting masticatory loads. This study evaluates and compares the mechanical robustness and the clinical reliability of these modified prostheses in cases of junctions of one or two contiguous prosthetic teeth. The 6-month follow-up demonstrated the total validity of the method via the absence of significant breakages or detachments in all of the patients analyzed; on the other hand, the prostheses modified using the traditional method and used as controls showed a high incidence of fractures.

Clinical Protocol for Implant-Assisted Partial Removable Dental Prostheses in Kennedy Class I: A Case Report

Patients with Kennedy Class I are usually treated with clasp-retained removable partial dentures (RPDs) as the prosthetic gold standard. For additional stabilization of the RPD, clinicians are often confronted with the question of secondary implant placement, which requires the fabrication of new prostheses. This case report is part of an ongoing multi-center randomized controlled study (RCT) investigating conventional RPDs without and with supplementary implants. A design of the RPD framework, including matrix housings, is crucial to enable subsequent implant retention or support. Ultra-short implants (Straumann TL 4.1 × 4 mm) offer the opportunity for additional support and retention in the edentulous posterior region, where bone availability is often reduced. This future-oriented and minimally invasive approach with virtual treatment planning and guided implant surgery offers the possibility of simplified functional and cost-effective aftercare.

Intaglio Surface Adaptation of Removable Partial Denture Framework Fabricated by Various Data Acquisition Techniques and Fabrication Approaches.

The aim of this study was to compare intaglio surface adaptation of the removable partial denture framework among various data acquisition techniques and fabrication approaches using three-dimensional comparison by metrology software. The partial edentulous typodont model with five digital superimposition landmarks was duplicated and scanned for the digital reference model. Three approaches were the conventional lost-wax (group I; LWT, n = 5), intraoral digital impressions combined with PolyJet printing and lost-wax (group II; IP-LWT, n = 5), and extraoral digital impressions combined with PolyJet printing and lost-wax (group III; EP-LWT, n = 5). Each framework was scanned and superimposed with the reference model. The misfits at 53 locations were measured. Data were statistically analyzed by one-way analysis of variance, followed by Tukey's honestly significant difference for pairwise comparisons (p < 0.05). Significant differences were found between three approaches at the reciprocal arm, terminal part of the retentive arm, rest, and major connector (p < 0.05). In the LWT group, the reciprocal arm and palatal vault region of major connector had the lowest misfits, but the highest misfit was found in the midline region (p < 0.001). In the IP-LWT group revealed the most excessive contact at the terminal part of the retentive arm (-0.111 ± 0.038 mm, p = 0.031), with the highest misfit at the rest area (p < 0.001). A difference in adaptation was found in several removable partial denture framework components among three approaches. The LWT group had a better adaptation than other groups. Nevertheless, a clinically acceptable adaptation was seen in all three approaches.

Wear, Fatigue and Fracture Resistance of Different Monolithic CAD/CAM Onlays As Abutments for Acetal Resin or Cobalt-Chromium Removable Partial Denture Frameworks.

To assess wear, fatigue, and fracture resistance of different CAD/CAM onlays, milled from monolithic Zirconia (Zr), hybrid ceramic (EN), and lithium disilicate (LS), when used as abutments for removable partial denture frameworks fabricated from acetal resin (AR) or cobalt-chromium (Co-Cr). Standard onlays and RPD framework were designed and milled using CAD/CAM. Onlays were cemented with resin cement to identical teeth models. The RPD's occlusal rest surface and the ceramic onlays' rest seats were both 3D scanned before and after 750,000 mechanical load cycles (50 N) and 8,000 thermal cycles (5-55°C) in a chewing simulator. The volumetric loss was measured using 3D image processing software, and the failure of the samples was detected using a stereomicroscope. The fracture resistance was tested by loading to failure in a universal testing machine. The fatigue failure results were analyzed with Fisher's exact probability test and the wear and fracture resistance data were analyzed using two-way ANOVA and Bonferroni Post-hoc test (P<0.05). A significant difference (p<0.05) was found between the tested experimental groups in wear, fatigue, and fracture resistance. Zr/Co-Cr combinations exhibited the least wear and the highest fatigue and fracture resistance (P<0.05), while the highest wear and least fatigue and fracture resistance were recorded for EN/AR group (p<0.05). Zr onlays demonstrated a conservative treatment option with superior mechanical behavior when used as an onlay abutment, regardless of the RPD framework material used. The AR framework is not recommended in the posterior region for removable partial dentures.

Evaluation on a teaching software for removable partial denture framework design.

Removable partial dentures (RPDs) are widely used as a dental prosthesis and have a wide application scope. To explore the effect of using design software in the preclinical teaching of removable partial dentures (RPDs). Unreal Engine software was used to build the RPD framework design teaching and training software. All 131 undergraduate students majoring in stomatology in the class of 2018, Kunming Medical University, were randomly divided into three groups and received either traditional experiment teaching, flipped classroom teaching, or software teaching for RPD design. The application effect of the software in the preclinical teaching of RPD design was evaluated by analyzing the examination results and through the use of a questionnaire survey. The differences in the theoretical examination scores among the traditional teaching group, the flipped classroom group, and the software teaching group were not statistically significant (P> 0.05), while the average design scores of upper Kennedy Class I and lower Kennedy Class II subclass II in the software teaching group were significantly higher than those in the traditional teaching group (P< 0.05). Overall, 75% of the students in the software teaching group reported that this teaching method could improve their learning initiative, a higher percentage than in the traditional teaching group (55.8%, P< 0.05). Meanwhile, 90.9% of the students in the software teaching group reported that the software could make RPD-related theoretical knowledge more visual and intuitive, and 93.2% of these students felt it was helpful for understanding the RPD three-dimensional (3D) spatial structure. These percentages were higher than those in the traditional teaching and flipped classroom groups (P< 0.05). In the preclinical teaching of RPD design, software training helped the students better understand the 3D structure of RPDs and establish clear design ideas, and it may also be valuable for in-depth research and promotion purposes.

Effect of different digital technology on the adaptation and retention of Co-Cr partial denture frameworks.

To evaluate the overall adaptation and retention of class I cobalt-chromium (Co-Cr) removable partial denture (RPD) frameworks using three different computer-aided design and computer-aided manufacturing (CAD-CAM) technologies: Indirect wax milling with lost wax technique (LWT), direct milling, and selective laser melting (SLM) technique. An educational maxillary stone model (Kennedy class I) was scanned after preparing rest seats to create a resin model. The resin model was scanned, and the RPD framework was digitally designed and saved as a standard tessellation language (STL) file. Twenty-four Co-Cr RPD frameworks were then constructed and divided into three groups (n = 8) based on fabrication technique: Group A (indirect wax milling with LWT), Group B (direct milling), and Group C (selective laser melting). In Group A, the STL file was used to mill the design from castable resin blanks which were then cast by the LWT. In Group B, the STL file was used to mill the design from the Co-Cr blank directly. Finally in Group C, the STL file was used to print the design from Co-Cr powder using SLM 3D printed technique. Geomagic Control X software was used to measure the overall adaptation of the fabricated RPD frameworks, Retention was also tested using a universal testing machine. One-way Analysis of Variance (ANOVA) test was used to compare the three groups then the Tukey HSD post-hoc test was used for pair-wise comparisons. The significance level was set at p ≤ 0.05. Regarding the overall adaptation, Group B (0.71±0.02mm) showed significantly higher adaptation than Group A (0.96±0.06mm) and Group C (1.05±0.16mm). Regarding retention, Group B (2.03±0.34 N) showed significantly higher retention than Group A (1.00±0.13 N) and Group C (0.78 ±0.17 N). Based on the findings of this in vitro study, Co-Cr RPD frameworks fabricated by direct milling technique revealed the best adaptation and retention.

Polyetheretherketone (PEEK) as a Biomaterial: An Overview.

Polyetheretherketone (PEEK) is a very powerful biomaterial that is increasingly used in dentistry. It has superior properties, which make it desirable in implantology. The applications of PEEK includefinger prosthesis, RPD and FPD framework, and dental implants. Changes in the production of polyketone-based materials have been made toensure consistent production of polymers for medical applications.PEEK isa high-performance semicrystalline material that has physical properties such as high resilience and strength. It is a tooth-colored material, making it desirable for its aesthetic appearance. Traditional manufacturingmethods like injection molding, extrusion, and compression molding are usedforPEEK. Despite the high price of the polymer, the additional value that PEEK materials bring by offering the possibility of manufacturing parts include lightweight, strength or toughness and able to survive longer in harsh environments.PEEK has trauma or shock cancelling abilities, fracture resisting abilities, stress distributing ability, osseointegrating abilities, With such great qualities PEEK has an increased demand in the market, and this biomaterial never failes to surprise with its amazing success rate.Even in dentistry PEEK has a wide range of applicationswhich includes, as a dental implants biomaterial, prosthetic material, abutment material, post and core material, crowns, removable partial denture framework. With such a huge range of applications PEEK is said to have been providing an all in one package for dentistry.PEEK biomaterial shows great compatibility with bioactive materials which has proven to be of great help to mankind as not only it is involved in life sciences but also in automotives and aerodynamics as well. The main motto of this review is to know the qualities and the properties of PEEK as a capable implant prosthesis for its application focusing on dental implants.This review tells us about the challenges faced when using this material and benefits and advantages ofthis biomaterial.

Fit and Retention of Cobalt-Chromium Removable Partial Denture Frameworks Fabricated with Selective Laser Melting.

To evaluate fit and retention of cobalt-chromium removable partial denture (RPD) frameworks fabricated with selective laser melting (SLM). Three types of framework for clasp-retained RPDs were virtually designed and fabricated using SLM (n = 30). For comparison, 30 additional frameworks were produced using conventional lost-wax casting. A biomechanical model was created, incorporating extracted teeth mounted on flexible metal posts. Using this model, horizontal constraint forces resulting from a misfit were measured using strain gauges, while vertical forces were not recorded. The constraint force components and resultant forces were determined for all abutment teeth, and the maximum retention force during RPD removal from the model was also assessed. For statistical evaluation, the two fabrication methods were analyzed by calculating the means and standard deviations. The average horizontal constraint forces showed similar values for both fabrication methods (SLM: 3.5 ± 1.0 N, casting: 3.4 ± 1.6 N). The overall scatter of data for cast RPDs was greater compared to those fabricated using SLM, indicating a better reproducibility of the SLM process. With regard to retention, the intended retention force of 5-10 N per abutment tooth was not attained in one of the cast groups, while it was consistently achieved in all SLM groups. This in vitro study found that SLM is a promising option for the manufacture of cobalt-chromium RPD frameworks in terms of fit and retention.

A digital chairside repair protocol for removable partial dentures with polyetheretherketone frameworks

Polyetheretherketone (PEEK) has become popular for removable partial denture (RPD) frameworks but reports on their clinical follow-up and repair are lacking. Two defective PEEK-framework RPDs were repaired with computer-aided design and manufacturing technology, saving costs and time and simplifying the treatment process.

Methods of Evaluating Adaptation and Accuracy of Additive Manufactured Removable Partial Dentures: A Scoping Review

This study aimed to provide a comprehensive review of various recent methods that can be used to assess the fit and accuracy of additive-manufactured removable partial dentures (RPDs), focusing on 3D-printed RPDs. An electronic search of the English language literature from January 2000 to February 2022 was performed using four databases: Medline/PubMed, Scopus, Web of Science, and EBSCOhost, using relevant keywords. The parameters of interest were extracted and tabulated. Of 936 retrieved studies, 26 studies were included. Most of the studies were laboratory studies, conducted between 2011 and 2022, did not include control group, used stone cast model as reference, used direct 3D printing method, and polished the final RPD framework. Methods of assessment can be divided into two categories: 1) qualitative assessment which is based mainly on visual inspection or tactile sense, and 2) quantitative assessment which includes optical assessment (with or without a registration material) and computerized assessment based on surface-matching software programs. In conclusion, computerized assessment using different surface matching software provides more accurate and precise quantitative assessment of denture fit and allows researcher and practitioner to detect minute dimensional changes that cannot be detected visually.

Laboratory evaluation of production efficiency for removable partial denture frameworks using in-house casting versus outsourced additive manufacturing techniques.

To compare the production efficiency of selective laser sintering (SLS) to traditional casting for the fabrication of metal prosthodontic frameworks in a prospective pilot evaluation in a hospital prosthodontic laboratory setting. The time taken to complete each of the identified stages in the production of 50 removable partial denture frameworks made using either SLS (n = 25) or casting (n = 25) workflows was measured. The mean time for production was calculated for each workflow, and the difference was tested for statistical significance. The results indicate that an SLS workflow may be more time-efficient, and further cost-effectiveness research is indicated.

Comparative Study of the Microstructure and Properties of Cast-Fabricated and 3D-Printed Laser-Sintered Co-Cr Alloys for Removable Partial Denture Frameworks.

Since additive technologies in dentistry are gradually replacing metal casting technology, it is necessary to evaluate new dental constructions intended for the development of removable partial denture frameworks. The aim of this research was to evaluate the microstructure and mechanical properties of 3D-printed, laser-melted and -sintered Co-Cr alloys, and perform a comparative study with Co-Cr castings for the same dental purposes. The experiments were divided into two groups. The first group consisted of samples produced by conventional casting of the Co-Cr alloy. The second group consisted of 3D-printed, laser-melted and -sintered specimens produced from a Co-Cr alloy powder divided into three subgroups, depending on the technological parameters chosen for manufacturing (angle, location and heat treatment). Examination of the microstructure was carried out by classical metallographic sample preparation, using optical microscopy and scanning electron microscopy with energy dispersive X-ray spectroscopy (EDX) analysis. A structural phase analysis was also performed by XRD. The mechanical properties were determined using a standard tensile test. The microstructure observation showed a dendritic character in the case of castings, while in the case of 3D-printed, laser-melted and -sintered Co-Cr alloys, the microstructure was typical for additive technologies. The XRD phase analysis confirmed the presence of Co-Cr phases (ε and γ). The results of the tensile test showed remarkably higher yield and tensile strength values and slightly lower elongation of the 3D-printed, laser-melted and -sintered samples than those produced by conventional casting.