Partial Denture Metal Framework Research Articles

Comparing the trueness of 3D printing and conventional casting for the fabrication of removable partial denture metal frameworks for patients with different palatal vault depths: An in vitro study

Statement of problemThe success of a removable partial denture depends on its fit, and, with conventional casting, the framework is more distorted in patients with a deep palatal vault. Questions remain about whether the three-dimensional (3D) printing technique for fabricating a framework can improve the accuracy of fit for these patients. PurposeThe purpose of this in vitro study was to compare the trueness of metal frameworks fabricated by selective laser melting, 3D printing pattern casting, and conventional casting for different palatal vault depths. Material and methodsA total of 30 partially edentulous maxillary casts were custom-made in 15 medium and 15 deep palatal vaults. All stone casts were scanned as reference models in digital files. For the medium palatal vault casts, Co-Cr frameworks of the conventional casting (CON) group (n=5) were fabricated with the lost wax technique. For the 3D printing pattern casting (PPC) group (n=5), wax patterns of the framework were printed, followed by metal casting. The frameworks created for the selective laser melting (SLM) group (n=5) were printed directly by using the SLM machine. The same procedures were followed for the deep palatal vault group. All the metal frameworks were scanned and superimposed with the reference casts by using the Geomagic Control X software program. Discrepancies were measured as mean ±standard deviation (trueness), and the data were statistically analyzed with a 2-way ANOVA test to evaluate the interaction of 2 independent factors (fabrication techniques and palatal vault depths) on a trueness outcome (α=.05). ResultsThe lowest mean ±standard deviation value was 0.092 ±0.023 mm, found from the SLM framework with deep palatal vault group, while the highest value was 0.194 ±0.017 mm, found from the CON framework with deep palatal vault group. Different fabrication techniques interacted with different palatal vault depths in terms of trueness (P<.05); however, no significant differences were observed in the medium palatal vault groups (P>.05). Additionally, color mapping demonstrated the gaps of metal frameworks among the 6 groups. ConclusionsWith the conventional casting technique, the accuracy of the metal framework was affected by the depth of the palate. For medium palatal vaults, all fabricated frameworks had clinically acceptable fit. For deep palatal vaults, the SLM frameworks showed the lowest discrepancy. As a result, the SLM technique is advised for fabricating a better-fitting metal framework for patients with a deep palatal vault.

Evaluation of Removable Partial Denture Metal Frameworks Produced by Digital Methods—A Systematic Review

(1) Introduction: This review aimed to synthesize the significant literature addressing digital techniques for producing removable partial denture (RPD) metal frameworks, focusing on oral fit outcomes. (2) Material and Methods: A systematic review of the Web of Science and Pubmed databases was performed according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines. The selection was for original articles in English containing relevant data on RPD metal frameworks produced with digital techniques, including study characteristics, digital techniques, and fit assessment methods and outcomes. (3) Results: From the 967 search studies, 405 were duplications, and 521 were excluded after screening against set criteria. A manual search included 21 studies resulting in 62 papers for review. Extra-oral was more frequently used than intra-oral scanning. The computer-assisted design was the most applied digital technique. Additive manufacturing was preferred to milling for direct and indirect fabrication of frameworks. Fit assessments were based on qualitative measures, but quantitative evaluation showed acceptable clinical fit for RPDs made by digital protocols. (4) Conclusions: The combination of direct metal additive manufacturing with conventional impression was the most used protocol and included better qualitative and quantitative fit outcomes than the other digital protocols.

Evaluation of trueness and precision of removable partial denture metal frameworks manufactured with digital technology and different materials.

The aim of this study is to evaluate the accuracy of removable partial denture (RPD) frameworks produced using different digital protocols. 80 frameworks for RPDs were produced using CAD-CAM technology and divided into four groups of twenty (n = 20): Group 1, Titanium frameworks manufactured by digital metal laser sintering (DMLS); Group 2, Co-Cr frameworks manufactured by DMLS; Group 3, Polyamide PA12 castable resin manufactured by multi-jet fusion (MJF); and Group 4, Metal (Co-Cr) casting by using lost-wax technique. After the digital acquisition, eight specific areas were selected in order to measure the Δ-error value at the intaglio surface of RPD. The minimum value required for point sampling density (0.4 mm) was derived from the sensitivity analysis. The obtained Δ-error mean value was used for comparisons: 1. between different manufacturing processes; 2. between different manufacturing techniques in the same area of interest (AOI); and 3. between different AOI of the same group. The Δ-error mean value of each group ranged between -0.002 (Ti) and 0.041 (Co-Cr) mm. The Pearson's Chi-squared test revealed significant differences considering all groups paired two by two, except for group 3 and 4. The multiple comparison test documented a significant difference for each AOI among group 1, 3, and 4. The multiple comparison test showed significant differences among almost all different AOIs of each group. All Δ-mean error values of all digital protocols for manufacturing RPD frameworks optimally fit within the clinical tolerance limit of trueness and precision.

Treatment of Partial Edentulous with Removable Partial Denture Metal Framework Combinated Thermoplastic - A Case Report

Abstract: Removable partial denture is a definitive prosthesis that has been used in dentistry for decades for the rehabilitation of partially edentulous patients. The visibility of the retentive arm in the metal denture sometimes causes esthetic problems for the patient. Therefore, aesthetic aspects should be considered to ensure patient satisfaction in dental treatment. This case report described oral rehabilitation using a combination of metal frame partial denture and thermo-plastic. A 40-year-old female patient with a history of old removable partial denture came to replace the old denture with a new one that was more aesthetic and showed no wire. The management of the patient included thorough anamnesis, extra and intra oral examinations, anatomic impression, determination of definitive treatment, preparation of rest on the abutment tooth, physiological impression, manufacturing of metal frameworks in the upper and lower jaws, determination of definitive vertical dimension, try-in denture, insertion, and control of combination of a metal frame partial denture with thermoplastic in the upper and lower jaws. The patient was satisfied with her new denture. In conclusion, the combination of a metal frame partial denture with thermoplastic can be an alternative treatment for patient who wants to replace his/her missing teeth with removable partial denture while still prioritizing aesthetic factors.Keywords: partial denture; metal frame; thermoplastic; retentive arm; aesthetics Abstrak: Gigi tiruan sebagian lepas (GTSL) ialah protesa definitif yang telah digunakan dalam bidang kedokteran gigi sejak beberapa dekade untuk rehabilitasi pasien dengan edentulus sebagian. Visibilitas lengan retentif pada GTSL kerangka logam kadang-kadang menyebabkan masalah estetis untuk pasien. Oleh karena itu aspek estetika harus dipertimbangkan untuk memastikan kepuasan pasien dalam perawatan gigi. Kami melaporkan kasus yang dilakukan tindakan rehabilitasi menggunakan kombinasi gigi tiruan sebagian kerangka logam dengan termoplastik pada seorang pasien perempuan berusia 40 tahun dengan riwayat GTSL lama. Pasien ingin mengganti dengan GTSL baru yang lebih estetis dan tidak tampak kawat. Tatalaksana pada pasien ini meliputi anamnesis yang cermat, pemeriksaan ekstra oral dan intra oral, pencetakan anatomis dan penentuan perawatan definitif, preparasi rest pada gigi abutment, pencetakan fisiologis, pembuatan kerangka logam di rahang atas dan bawah, penentuan dimensi vertikal definitif, percobaan gigi, insersi, serta kontrol kombinasi gigi tiruan sebagian kerangka logam dengan termoplastik pada rahang atas dan bawah. Pasien merasa puas akan kombinasi gigi tiruan kerangka logam dengan termoplastik. Simpulan studi ini ialah kombinasi gigi tiruan sebagian kerangka logam dengan termoplastik dapat menjadi alternatif perawatan untuk mengganti gigi yang hilang dengan GTSL serta tetap mementingkan faktor estetika.Kata kunci: gigi tiruan sebagian; kerangka logam; termoplastik; lengan retentif; estetis

Fit accuracy of removable partial denture metal frameworks produced by CAD-CAM – a clinical study

Objectives: To assess the effect of a CAD-CAM protocol fabrication on the clinical fit accuracy of removable partial denture metal frameworks to abutment teeth. Methods: Fifteen patients with partial edentulism were selected to participate in this clinical study, and twenty dental arch rehabilitations were planned. For each dental arch (n=20), two cobalt-chromium frameworks were produced through two protocols: CAD-CAM production (experimental group); and conventional lost-wax casting technique (control group). Clinical fit accuracy was assessed using an indirect quantitative method to evaluate the gap between the framework occlusal rest and the corresponding rest seat. A silicone mold of that gap was obtained, digitized, and analyzed by micro-computed tomography. The two silicone molds obtained for each occlusal rest were overlapped and evaluated for thickness and volume. Data were analyzed with the paired t test for silicone thickness results and the Wilcoxon test for silicone volume results (α= 0.05). Results: Considering the two dependent variables under study, no statistically significant (p=0.441 for silicone thickness and p=0.204 for silicone volume) differences were found between groups. Conclusions: The results of this study suggest that the CAD-CAM protocol applied is a viable method for the production of removable partial denture metal frameworks. (Rev Port Estomatol Med Dent Cir Maxilofac. 2021;62

Fractographic analysis of two fractured removable partial denture metal frameworks

This study aimed to analyze two cases of fracture of the metal framework of Co-Cr-based removable partial dentures, using fractography to identify a true cause of these failures. The first case concerned the coupling between the smaller and larger connectors; the patient brought his fractured removable partial dentures to the clinic. The second case referred to a larger connector; structure of the patient fractured during the test. For failure analysis, images of two fractured metal frameworks were taken by scanning electron microscopy to identify the origin of the fracture and to determine the mechanisms involved in the process. Subsequently, energy dispersive X-ray spectroscopy was used for elemental chemical mapping of the fracture interface. The fractography indicated material fatigue as a possible cause in the first case and an error in the casting process in the second. The energy dispersive X-ray spectroscopy test, performed in the specimen of case B, showed predominant and characteristic peaks for Co and Cr, with a higher concentration of chromium. The fractures identified were associated with inclusions and with material fatigue and a number important characteristics were evidenced by the technique.

Removable partial denture metal framework manufactured by selective laser melting technology – A clinical report

The selective laser melting technology is an additive digital method that permits producing metal frameworks for removable partial dentures. The existing literature has compared this technique with the classic technique in terms of precision, quality of fit, and function. This work describes a clinical case of a metal framework produced by the selective laser melting technique in a patient rehabilitated with a removable partial denture. No adjustments were required when the metal framework was inserted, showing good adaptation and stability to the abutment teeth and surrounding tissues. Further studies are necessary for a significant assessment of this technique’s clinical applicability.

Association of fit of partial denture metal framework with various framework design features using alginate as a final impression material: A prospective clinical study

ObjectivesTo assess the fit of PRDP frameworks fabricated using alginate as a final impression material in metal stock trays, in terms of number of fabricated frameworks needed until realization of clinically adequate fit. Also, any association of framework fit achieved with its design features, namely major connector design, and numbers of guide plates and occlusal/incisal rests was investigated. Methods147 partially dentate patients were provided with Co-Cr PRDPs, in single or both arches, by undergraduate dental students. Final impressions were made with alginate in metal stock trays. At metal framework try-in, clinical examinations were carried out by two prosthodontists and relevant information noted with regard to proper fit. The relationship between three PRDP design features and number of frameworks that needed to be made in each case to achieve satisfactory fit was determined using factorial analysis of variance (ANOVA) (α = 0.05). Results86% (148) of the 173 frameworks fabricated were found to be clinically satisfactory at the first try-in visit (with or without any chairside adjustment). The remaining 14% (25) required new impressions for re-fabrication and passed at the second attempt. None of the examined design features were significantly associated with the number of construction attempts needed, for all 173 arches, or when maxillary and mandibular arches were considered independently (p > 0.05). ConclusionsPRDP design features were not associated with the level of accuracy of fit achieved. Clinical significanceAlginate in metal stock trays seems to be acceptable for final impressions of all types of Co-Cr PRDP designs with just 1 in 7 castings not fitting after chairside adjustment.

The Fit Accuracy of Removable Partial Denture Metal Frameworks Using Conventional and 3D Printed Techniques: An In Vitro Study

To evaluate the accuracy of removable partial denture (RPD) metal frameworks fabricated by the conventional lost-wax (CLW) technique and those made by the selective laser melting (SLM). A dentoform of a mandibular Kennedy class III, modification 1 dental arch were surveyed, and rest seats were prepared on the abutment teeth. The dentoform was then duplicated into a metal die which was used as a reference model. Thirty RPD metal frameworks were fabricated by two techniques; fifteen for each technique. Polyvinyl siloxane (PVS) impression material was painted on the intaglio surface of the rests of each framework which is then seated on the reference die. PVS specimens that represent the gap under the rest were measured in four zones: buccal, lingual, marginal and central by a single examiner using a digital microscope at 50x in micrometers. Comparison between the two techniques for each abutment tooth revealed that the CLW technique had better fit in one tooth, while the SLM technique showed a better fit in two teeth. Regarding the edentulous span length within the SLM technique, the long edentulous span had a significantly better fit. When comparing the four measured rest zones, it was found that in the CLW technique group, the marginal zone had the highest fit accuracy while the lingual zone showed the lowest fit accuracy. In the SLM group, the central zone had the best fit and the buccal zone had the worst fit. RPD frameworks fabricated using the SLM technique showed better fit accuracy than those made by the CLW technique, however, the difference was not statistically significant. SLM is a promising technique for the fabrication of RPD frameworks in routine clinical practice.

Comparison of internal adaptation of removable partial denture metal frameworks made by lost wax technique and printing technique of pattern using CAD

가철성 국소의치의 금속구조물을 제작하는 방법은 왁스 패턴을 제작하여 주조하는 lost wax technique이 주로 사용되어 왔으나, 디지털 기술의 발달로 서베잉과 금속구조물을 CAD (Computer aided design)로 디자인하여 제작할 수 있게 되었다. 여러 증례에서 CAD를 이용한 pattern의 프린팅 방식으로 얻은 레진 패턴이 구...

Partial denture metal framework may harbor potentially pathogenic bacteria.

PURPOSEThe aim of this study was to characterize and compare bacterial diversity on the removable partial denture (RPD) framework over time.MATERIALS AND METHODSThis descriptive pilot study included five women who were rehabilitated with free-end mandibular RPD. The biofilm on T-bar clasps were collected 1 week (t1) and 4 months (t2) after the RPD was inserted (t0). Bacterial 16S rDNA was extracted and PCR amplified. Amplicons were cloned; clones were submitted to cycle sequencing, and sequences were compared with GenBank (98% similarity).RESULTSA total of 180 sequences with more than 499 bp were obtained. Two phylogenetic trees with 84 (t1) and 96 (t2) clones represented the bacteria biofilm at the RPD. About 93% of the obtained phylotypes fell into 25 known species for t1 and 17 for t2, which were grouped in 5 phyla: Firmicutes (t1=82%; t2=60%), Actinobacteria (t1=5%; t2=10%), Bacteroidetes (t1=2%; t2=6%), Proteobacteria (t1=10%; t2=15%) and Fusobacteria (t1=1%; t2=8%). The libraries also include 3 novel phylotypes for t1 and 11 for t2. Library t2 differs from t1 (P=.004); t1 is a subset of the t2 (P=.052). Periodontal pathogens, such as F. nucleatum, were more prevalent in t2.CONCLUSIONThe biofilm composition of the RPD metal clasps changed along time after RPD wearing. The RPD framework may act as a reservoir for potentially pathogenic bacteria and the RPD wearers may benefit from regular follow-up visits and strategies on prosthesis-related oral health instructions.

베릴륨 불포함 치과 주조용 니켈-크롬 합금 중 금속의치상용 합금과 금속소부도재관용 합금의 부식에 관한연구

Purpose: This study examined the corrosion level by alloy type and pH, and used the corrosion levels as the dental health data. The study utilized one Ni-Cr alloy for the full and removable partial denture metal frameworks and two Ni-Cr alloys for porcelain-fused-to-metal crown, among the non-beryllium dental casting non-precious Ni-Cr alloys. Methods: The alloy specimens were manufactured in <TEX>$10cm^2$</TEX> and stored in the corrosive solution(pH 2.2-4.4) in the electrical water bath(<TEX>$37^{\circ}C$</TEX>) for seven days. Afterwards, the metal ions were quantitatively analyzed using the ICP. Results: Of the three metal alloys, Bellabond-Plus<TEX>$^{(R)}$</TEX>alloy and SOLIBOND N<TEX>$^{(R)}$</TEX>alloy, with 22% or higher chrome chemical contents, had higher corrosion resistance than Jdium-100<TEX>$^{(R)}$</TEX>alloy with 20% chrome chemical content. In all three alloys, the corrosion of Ni was highest, and metal ion corrosion was higher in the pH 2.2 corrosive solution. Conclusion: Although Ni-Cr alloy was not very corrosive, a Ni-allergic patient should not have Ni-Cr alloy prosthesis. The Ni-Cr alloy for porcelain-fused-to-metal crown should be designed for the dental porcelain to cover the whole crown.

총의치와 국소의치 금속의치상용 코발트-크롬 합금과 금속소부도재관용 코발트-크롬 합금의 부식저항성 평가

Purpose: This study was conducted to evaluate the corrosion resistance of metal ions of alloys and use the results as the dental health data. These were performed by examining the corrosion levels of Co-Cr alloys for the full and removable partial denture metal frameworks and porcelain-fused-to-metal crown, among the dental casting nonprecious alloys. Methods: The alloy specimens (N = 10) were manufactured in <TEX>$15mm{\times}10mm{\times}1.2mm$</TEX> and stored in two types of corrosive solutions at <TEX>$37^{\circ}C$</TEX> for seven days. The metal ions were quantitatively analyzed using the Inductively Coupled Plasma-Atomic Emission Spectrometer. Results: Of the three Co-Cr alloys, the Co ion concentration of the porcelain-fused-to-metal alloy was 1.512 <TEX>${\mu}g/cm^2$</TEX>, which indicated the highest metal ion dissolution. The metal corrosion was higher in the more acidic pH 2.2 solution compared with the pH 4.4 solution. In all three Co-Cr alloys, Co ion dissolution was predominant in the two corrosive solutions. Conclusion: The corrosion resistance of the three Co-Cr alloys was high, indicating a good biocompatibility.

A Study on Effect of Surface Treatments on the Shear Bond Strength between Composite Resin and Acrylic Resin Denture Teeth

Visible light-cured composite resins have become popular in prosthetic dentistry for the replacement of fractured/debonded denture teeth, making composite denture teeth on partial denture metal frameworks, esthetic modification of denture teeth to harmonize with the characteristics of adjacent natural teeth, remodelling of worn occlusal surfaces of posterior denture teeth etc. However, the researches published on the bond strength between VLC composite resins and acrylic resin denture teeth is very limited. The purpose of this study is to investigate the effect of five different methods of surface treatments on acrylic resin teeth on the shear bond strength between light activated composite resin and acrylic resin denture teeth. Ninety cylindrical sticks of acrylic resin with denture teeth mounted atop were prepared. Various treatments were done upon the acrylic resin teeth surfaces. The samples were divided into six groups, containing 15 samples each. Over all the treated and untreated surfaces of all groups, light-cured composite resin was applied. The shear strengths were measured in a Universal Testing Machine using a knife-edge shear test. Data were analyzed using one way analysis of variance (ANOVA) and mean values were compared by the F test. Application of bonding agent with prior treatment of methyl methacrylate on the acrylic resin denture teeth resulted in maximum bond strength with composite resin.

Strain on the framework of a mandibular free-end saddle partial denture under load.

AbstractStrains were determined in a typical mandibular partial denture metal framework of the free‐end saddle type. The overall strain patterns were determined using a brittle lacquer coating technique and loads were applied vertically to positions on the saddles. The results from the coating study indicated the area of high strain were just anterior and posterior to the finishing lines. Strain gages were attached to positions anterior and posterior to the finishing lines and the strain was measured at these positions when the saddles were loaded either at a posterior or anterior position at intervals of 2 lb up to 20 lb. When a static load of 20 lb was applied to the posterior of the left saddle a strain of 750 μ in./in. was obtained, which for the alloy used was equivalent to a stress of 22,200 lb/in.2. The amount of strain observed was a function of the length of the saddle, the bulk of the framework, the relation of the site of the gage to the position of loading, the presence of an indirect retainer, and the position of the fulcrum for the loading conditions used.