Fabrication Of Inlays Research Articles

Research on Textured Polishing Wheel (TPW) patterns for polishing dental ceramic materials in anhydrous environments

Abstract Dental ceramics commonly utilize high-hardness fused silica materials for the fabrication of inlays, crowns, and artificial dental implants, with their processing efficiency and surface roughness (Ra) directly influencing manufacturing costs and product quality. This study presents the development of a Textured Polishing Wheel (TPW) featuring three distinct surface patterns (spiral, linear, and radial), achieved through single-point diamond and pulsed laser processing techniques. It investigates the effects of these patterns on the removal rate and surface roughness (Ra) of dental ceramics during the polishing process. Results indicate that while TPW demonstrates comparable material removal depth to non-textured polishing wheels, it marginally increases surface roughness (Ra). Moreover, TPW significantly reduces burning and wear on the wheel surface during polishing. Pulsed laser ablation of TPW leads to further improvement in surface roughness, thereby enhancing the processing of dental ceramics. Experimental findings highlight the superior performance of spiral TPW, achieving a material removal rate of 4.2 μm/h and a surface roughness (Ra) of approximately 2.2 nm , thus meeting the manufacturing and functional requirements of dental ceramics.

A data-driven approach for the partial reconstruction of individual human molar teeth using generative deep learning.

Due to the high prevalence of dental caries, fixed dental restorations are regularly required to restore compromised teeth or replace missing teeth while retaining function and aesthetic appearance. The fabrication of dental restorations, however, remains challenging due to the complexity of the human masticatory system as well as the unique morphology of each individual dentition. Adaptation and reworking are frequently required during the insertion of fixed dental prostheses (FDPs), which increase cost and treatment time. This article proposes a data-driven approach for the partial reconstruction of occlusal surfaces based on a data set that comprises 92 3D mesh files of full dental crown restorations. A Generative Adversarial Network (GAN) is considered for the given task in view of its ability to represent extensive data sets in an unsupervised manner with a wide variety of applications. Having demonstrated good capabilities in terms of image quality and training stability, StyleGAN-2 has been chosen as the main network for generating the occlusal surfaces. A 2D projection method is proposed in order to generate 2D representations of the provided 3D tooth data set for integration with the StyleGAN architecture. The reconstruction capabilities of the trained network are demonstrated by means of 4 common inlay types using a Bayesian Image Reconstruction method. This involves pre-processing the data in order to extract the necessary information of the tooth preparations required for the used method as well as the modification of the initial reconstruction loss. The reconstruction process yields satisfactory visual and quantitative results for all preparations with a root mean square error (RMSE) ranging from 0.02 mm to 0.18 mm. When compared against a clinical procedure for CAD inlay fabrication, the group of dentists preferred the GAN-based restorations for 3 of the total 4 inlay geometries. This article shows the effectiveness of the StyleGAN architecture with a downstream optimization process for the reconstruction of 4 different inlay geometries. The independence of the reconstruction process and the initial training of the GAN enables the application of the method for arbitrary inlay geometries without time-consuming retraining of the GAN.

Accuracy of complete-arch intraoral scans based on confocal microscopy versus optical triangulation: A comparative in vitro study

Statement of problemFully digital dentistry is contingent on an accurate digital scan of the complete arch; however, the dimensional accuracy of different scanners for digitizing a complete arch is unclear. PurposeThe purpose of this in vitro study was to compare the accuracy of 2 intraoral scanners, TRIOS 3 (TR) and CEREC Omnicam (OC). Accuracy was assessed from changes to reference distances defined along the complete arch of a reference cast including 3 precision balls and 3 prepared teeth. The local accuracy (trueness and precision) of the scanned surface of each prepared tooth was also assessed. Material and methodsEach intraoral scanner was used to scan a metal mandibular reference cast 20 times in a randomized sequence. The complete dental arch of a mandible in which the second left premolar was missing contained 2 prepared teeth, the first left premolar (LP) and the first left molar (LM) to accommodate a fixed partial denture (FPD) with complete crowns. The arch also contained an inlay preparation on the right second premolar (RP). Stainless-steel precision balls (ball centers P1, P2, and P3), which were welded onto the left second molar (P1), the incisal contact point of the central incisors (P3), and the right first molar (P2), were used to determine dimensional changes over the complete arch. Powder (CEREC Optispray) was applied to the reference cast to reduce reflections. Deviations between the reference cast (digitized with high precision before the tests) and the intraoral scans were calculated using Matlab R2015a and Geomagic Design X. To evaluate dimensional changes, the centers of the balls were determined, and their absolute changes in distance (ΔP1P2, ΔP1P3, and ΔP2P3) were calculated. To calculate accuracy (trueness and precision) in relation to the prepared teeth, the mesh deviation between the intraoral scans and the superimposed reference teeth was determined. The data were statistically analyzed by using a nonparametric rank-based 2-way repeated-measures ANOVA, and differences in least square means for pairwise comparisons were calculated (α=.05). ResultsThe following mean absolute changes in distance were determined: ΔP1P2, TR: 74.4 μm, OC: 119.6 μm; ΔP1P3, TR: 24.7 μm, OC: 17.2 μm; ΔP2P3, TR: 68.6 μm, OC: 41.2 μm. The scanner did not have a statistically significant effect (P=.118) for distance, and the different distances differed significantly from each other (P<.001). Both scanners provided results acceptable for the fabrication of inlays and short-span FPDs. A complete-crown scan was more accurate than an inlay scan (P<.001). Accuracy and precision were better for TR than for OC (P<.001). ConclusionsWith maximum discrepancies of 192.5 to 294.6 μm across the dental arch, complete-arch scans cannot yet be recommended for the fabrication of long-span FPDs.

The effects of recasting on the cytotoxicity of dental base metal casting alloys.

Aim and Objectives:In dentistry, base metal casting alloys are extensively used for the fabrication of inlays, onlays, crowns, bridges, partial dentures, etc. During the casting of these alloys, excess amount of material used than needed will be collected as sprue buttons at the end, which is either added to the fresh alloy during casting and reused or disposed of.Materials and Methods:The aim of the present in vitro experimental study was to investigate the effect of the complete recasting of four commercially available cobalt-chromium (Co-Cr) and nickel-chromium (Ni-Cr) base metal casting alloys on their cytotoxicity. During the study, four groups of alloys were subjected to complete recasting up to twenty times without the addition of new alloy. The cytotoxicity assessment of the selected alloys after recasting (Co-Cr and Ni-Cr alloys) was carried out using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay.Results:The results indicated that Co-Cr alloys exhibit superior cell viability compared to Ni-Cr alloys, and cytotoxic potential of the alloys increased with repeated casting and led to increased cell death. The recasting of alloys in the present study did not show high cytotoxicity even after the 20th recasting.Conclusion:From the results of the present study, it can be concluded that the alloys generated as a waste in the dental laboratory can be safely reused up to five times or at least once before they can be disposed, which reduces the cost of the treatment and also helps in conserving the natural resources.

Production of Dental Inlay Wax Using Locally Sourced Materials in Enugu, Nigeria

Dental inlay wax is a mixture of several waxes, usually containing paraffin wax, ceresin wax, beeswax and other natural and synthetic waxes. It is used to prepare patterns for gold or other metallic materials in the fabrication of inlays, crowns and bridges. Inlay wax is used for the same purpose as casting wax in the formation of pattern mostly for metallic casting in Dental technology. This study aimed at producing dental inlay wax using locally sourced materials in Enugu, Nigeria. The research was carried out between July to September, 2018 in Enugu, Nigeria. The study adopted a three phased experimental approach using the same procedures but different weight compositions. Structured, pretested Product Evaluation Data Sheet was used to evaluate the product by selected Practicing Dental Technologists in Enugu State, Nigeria. The resultant wax from experiment III with the following composition: 60g Paraffin wax, 5g Beeswax, 25g Carnauba wax, 10g Ceresin wax and (35g) of green ketchup colorant gave the best result. Its properties are comparable to the conventional Dental Inlay wax. There was significant agreement among the respondents in the smoothness of the product (40%); excellent dimensional stability and product effectiveness (40%); flow and burnout of the product (35%), and color stability of the product (45%). These findings suggests that dental inlay waxes can be produced locally in Enugu, Nigeria. Therefore, more attention needs to be paid in the production process, which will facilitate easy practice of Dental Technology, and also conserve huge foreign exchange being spent in the importation of inlay wax in Nigeria.

Survival rate and load to failure of premolars restored with inlays: An evaluation of different inlay fabrication methods

Statement of problemStudies that evaluate the survival rate and load to fracture of premolars restored with inlays produced using different methods are lacking. PurposeThe purpose of this in vitro study was to compare the survival rate and fracture load of premolars restored with inlays fabricated using different methods. Material and methodsThirty maxillary premolars were selected, embedded, and prepared to receive inlays fabricated using different methods (n=10): LaCom-digital scanning with Lava C.O.S. scanner (3M ESPE), followed by milling of composite resin block (Lava Ultimate; 3M ESPE) in a milling unit; CeCom-digital scanning with Cerec 3D Bluecam scanner (Dentsply Sirona), followed by milling of a Lava Ultimate block in Cerec (Dentsply Sirona); PresDis-impression with polyvinyl siloxane, inlay made using the lost wax technique, and IPS e.max Press (Ivoclar Vivadent AG) pressed ceramic (lithium disilicate). A dual-polymerizing resin cement system was used to lute the inlays. Inlays were mechanically cycled (2 Hz, 106 mechanical pulses, 80 N) after 24 hours, and the specimens were stored in distilled water at 37°C for 11 months. Then, a fatigue test was conducted using a 10-Hz frequency and 400-N load on the inner inclines of the cusps. The test was complete when the specimen fractured or when the specimen reached 1.5×106 cycles. The specimens that survived fatigue testing were submitted to a single-load fracture test in a universal testing machine and analyzed using a stereoscope for failure classification. Survival rates were estimated using the Kaplan-Meier method and log-rank test (Mantel-Cox). Fracture load data were analyzed using 1-way ANOVA (α=.05). ResultsNo significant differences were detected among the groups for the survival rate (P=.87) or for the load to fracture (P=.78). Most failures were longitudinal, catastrophic fractures. ConclusionsPremolars restored with inlays fabricated using the tested methods had similar survival rates and loads to fracture.

Comparison of dimensional stability of die stone and die silicone: An In Vitro comparative study

Background: Die silicone is used for making dies for chair side fabrication of inlays and onlays. Die silicone material is user friendly and fast setting but undergoes shrinkage. Aim: To compare the dimensional stability between Die stone and Die Silicone. Methods: A metal die with known dimensions is made. Impressions of the metal die are made with Polyether impression material. Dies are made out of Die Stone and Die Silicone. The Dimensions of the reproduced details are measured and compared. Results: Both Die Stone and Die Silicone produce comparable results. Conclusion: As Die Silicone is made of Polymer, its dimensional stability is a query. But in the study it was found that, they had similar results. With the advantages of fast setting, chipping and abrasion resistance, it would make Die Silicone a more user friendly material of choice for die making.

Survival rate of restored premolars: Evaluation of inlay fabrication methods

Survival rate of restored premolars: Evaluation of inlay fabrication methods

CAD/CAM versus traditional indirect methods in the fabrication of inlays, onlays, and crowns

CAD/CAM versus traditional indirect methods in the fabrication of inlays, onlays, and crowns

乳歯に対するCELAY®セラミックスインレー・アンレーの応用について

乳歯に対するCELAY®セラミックスインレー・アンレーの応用について

A die sawing technique

A technique for separating dies when there is insufficient space for a saw blade to cut between them has been described. The technique can be used in crown, fixed partial denture, and indirect inlay fabrication, and it eliminates the possibility of damaging dies by sawing between them from the occlusal surface of the cast.

Hydrocolloid Techniques in the Fabrication of Inlays by the Indirect Method: Update on Alternative Delivery Systems

Clinical success with the hydrocolloids depends on careful control of the many manipulative variables. With intelligent manipulation, the exactness of duplication of cavities allows multiple restorations to be coordinated one with the other on hydrocal models without the necessity of checking or fitting in the mouth. The main factors are: 1. Reversible hydrocolloid must be boiled for a minimum of 10 minutes and stored at a temperature of 145° or 155° F. 2. Various tempering procedures can be employed, but the degree of gelation and the working consistency will depend on batch composition, tempering temperature and time. 3. The cavity margin must be exposed, since neither agar nor alginate hydrocolloids will displace tissue or heavy fluids. Retraction of tissue should be by means of conservative methods in order to minimize trauma. 4. The impression must be held in the patient’s mouth for a minimum of 5 minutes and removed with a sharp thrust in one direction parallel to the long axis of the tooth. 5. For indirect techniques, most alginates require a higher water-powder ratio and the use of ice water for proper control of the setting time. 6. Either premature removal or a prolonged period in the mouth will influence the accuracy of alginate impressions. 7. Both agar and alginate impressions must be poured within 15 minutes. 8. The water-powder ratio, the amount of vibration during pouring and the length of time before removal of the die will influence the character of the stone surface. 9. The working dies show no discrepancies when the fractured parts are trimmed and the metal strips are not too thick or pushed too far into the impression.

Application of Basic Sciences to Gold Inlay Fabrication

Application of Basic Sciences to Gold Inlay Fabrication