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Journal of Dentistry May 2024To evaluate whether post-milling firing and material type affect the fabrication trueness and internal fit of lithium disilicate crowns.
OBJECTIVES
To evaluate whether post-milling firing and material type affect the fabrication trueness and internal fit of lithium disilicate crowns.
METHODS
A prefabricated cobalt chromium abutment was digitized to design a mandibular right first molar crown. This design file was used to fabricate crowns from different lithium disilicate ceramics (nano-lithium disilicate (AM), fully crystallized lithium disilicate (IN), advanced lithium disilicate (TS), and lithium disilicate (EX)) (n = 10). Crowns, the abutment, and the crowns when seated on the abutment were digitized by using an intraoral scanner. Fabrication trueness was assessed by using the root mean square method, while the internal fit was evaluated according to the triple scan method. These processes were repeated after the post-milling firing of AM, TS, and EX. Paired samples t-tests were used to analyze the effect of post-milling firing within AM, TS, and EX, while all materials were compared with 1-way analysis of variance and Tukey HSD tests (α = 0.05).
RESULTS
Post-milling firing reduced the surface deviations and internal gap of AM and EX (P ≤ 0.014). AM mostly had higher deviations and internal gaps than other materials (P ≤ 0.030).
CONCLUSIONS
Post-milling firing increased the trueness and internal fit of tested nano-lithium disilicate and lithium disilicate ceramics. Nano-lithium disilicate mostly had lower trueness and higher internal gap; however, the maximum meaningful differences among tested materials were small. Therefore, the adjustment duration and clinical fit of tested crowns may be similar.
CLINICAL SIGNIFICANCE
Tested lithium disilicate ceramics may be suitable alternatives to one another in terms of fabrication trueness and internal fit, considering the small differences in measured deviations and internal gaps.
Topics: Dental Porcelain; Crowns; Humans; Dental Prosthesis Design; Computer-Aided Design; Materials Testing; Dental Abutments; Ceramics; Surface Properties; Dental Materials; Dental Marginal Adaptation; Chromium Alloys
PubMed: 38580056
DOI: 10.1016/j.jdent.2024.104987 -
Journal of Esthetic and Restorative... Apr 2024Occlusal reconstruction is a critical intervention for patients with dental hard tissue defects, temporomandibular joint (TMJ) disorders, and jaw position abnormalities....
OBJECTIVE
Occlusal reconstruction is a critical intervention for patients with dental hard tissue defects, temporomandibular joint (TMJ) disorders, and jaw position abnormalities. Clinical efficiency and outcomes of these procedures have improved with advances in digital technologies. This case report aims to illustrate a comprehensive digital workflow for occlusal reconstruction in a patient with congenital dentition defects, emphasizing the application of digital technologies to enhance treatment outcomes.
CLINICAL CONSIDERATIONS
A 28-year-old woman with previously installed porcelain-fused-to-metal bridge restorations presented with a fractured prosthesis and TMJ symptoms. A multidisciplinary approach was adopted involving the use of digital facebow, intraoral scanners, digital smile design, and CAD/CAM technologies. The process included the extraction of defective restorations, temporary restorations to refine jaw position, and final permanent restorations. The digital workflow facilitated precise diagnostics and treatment, culminating in the successful installation of permanent restorations. Regular follow-ups at one- and three-months post-treatment confirmed stable occlusal function and high patient satisfaction.
CONCLUSIONS
This case report showcases the potential of multiple digital technologies to streamline complex dental treatments and achieve high-quality results.
CLINICAL SIGNIFICANCE
The integration of digital technologies in occlusal reconstruction treatments offers significant benefits in terms of precision, patient comfort, and esthetic outcomes.
PubMed: 38563216
DOI: 10.1111/jerd.13234 -
Cureus Feb 2024Sjögren's syndrome is a chronic, inflammatory autoimmune disorder characterized by lymphocyte infiltration of the exocrine glands. Notably, the rehabilitation of...
Sjögren's syndrome is a chronic, inflammatory autoimmune disorder characterized by lymphocyte infiltration of the exocrine glands. Notably, the rehabilitation of partially edentulous patients with Sjögren's syndrome is limited by the scarce availability of studies that could inform therapeutic modalities and potential challenges during clinical procedures. This case report aimed to present the oral rehabilitation of a patient with Sjögren's syndrome who received fixed partial dentures (FPDs). A 28-year-old female patient sought treatment to restore her missing teeth. She was diagnosed with Sjögren's syndrome by a rheumatologist adhering to the revised version of the European criteria proposed by the American-European Consensus Group and was on a medication regimen including prednisolone, hydroxychloroquine, pantoprazole, pilocarpine, and tear substitutes to manage her condition. The final treatment plan consisted of extractions, management of gingivitis, post-and-core restorations, and a 2 mm vertical dimension increase with the placement of 15 porcelain-fused-to-metal (PFM) crowns and 4 short-span bridges. The patient underwent regular clinical and radiographic evaluations every 3 months since June 2020. Throughout this period, the fixed prostheses, teeth, and periodontal tissues demonstrated remarkable stability and exhibited no complications. This three-year case study provides evidence that meticulous planning and clinical execution can facilitate successful oral rehabilitation in young edentulous patients with Sjögren's syndrome. Tooth-supported fixed prostheses can effectively restore oral function and aesthetic appeal in these individuals, provided they undergo more frequent dental examinations than the general population and maintain a cooperative attitude throughout the treatment process.
PubMed: 38558652
DOI: 10.7759/cureus.55148 -
The Journal of Prosthetic Dentistry Jun 2024Natural teeth are graded in terms of translucency and strength. Graded zirconia materials are now available with a higher yttria content on the top or in the enamel zone...
STATEMENT OF PROBLEM
Natural teeth are graded in terms of translucency and strength. Graded zirconia materials are now available with a higher yttria content on the top or in the enamel zone to increase surface translucency and a lower yttria content on the bottom or in the dentin zone to increase strength. Such materials could provide multiple advantages over uniform materials and reduce the need for porcelain veneering in anterior artificial crowns; however, studies on the properties of these materials are lacking.
PURPOSE
The purpose of this in vitro study was to measure and compare the biaxial flexural strength, percentage light transmission, elemental content, and phase content of zones within and among color graded zirconia blocks and color- and strength-graded zirconia blocks.
MATERIAL AND METHODS
Disks of a color graded material (Katana STML) and a strength- and color-graded material (IPS e.max ZirCAD Prime) were fabricated (Zircom Furnace). Biaxial flexural strength was measured using a piston-on-3-ball test in a universal testing machine (n=10). Absolute light transmission was measured with a spectrophotometer. Elemental compositions were quantified for 3 zones in each of the 2 zirconia materials using X-ray fluorescence analysis. Zirconia phase fractions were quantified for 3 zones using X-ray diffraction analysis (XRD). Where appropriate, 2-way ANOVA, 1-way ANOVA, and Tukey multiple pairwise comparison testing were used to determine which of the 6 zones differed from one another (α=.05).
RESULTS
The color-graded zirconia exhibited gradients in light transmission and differences in phase content in the 3 zones measured. The color- and strength-graded zirconia exhibited gradients in light transmission, biaxial flexural strength, elemental composition, and phase content in the 3 zones measured. The bottom, dentin, or intaglio layer of a strength graded zirconia material was substantially stronger than all other zones of either material (P<.05). The top, enamel, zones of both materials possessed high light transmissibility (P<.05). The 2 materials differed with respect to biaxial strength (P<.001), light transmission (P<.02), elemental composition, and phase composition overall, as well as in most zone-by zone comparisons (P<.05). The performance and composition of the color graded material was consistent with it being a 5Y material throughout. The performance and composition of the color and strength graded material was consistent with it having a 3Y bottom zone and a 5Y top zone.
CONCLUSIONS
A strength-graded and color-graded zirconia material offers potential advantages in both strength and translucency.
Topics: Zirconium; Materials Testing; Color; Flexural Strength; Dental Stress Analysis; Dental Materials; Light; Surface Properties; Humans; In Vitro Techniques; Yttrium
PubMed: 38555268
DOI: 10.1016/j.prosdent.2024.03.015 -
Journal of Dentistry Mar 2024To evaluate the clinical conditions of single-unit posterior restorations on teeth prepared without finishing line, after 5.6 years of clinical service.
OBJECTIVE
To evaluate the clinical conditions of single-unit posterior restorations on teeth prepared without finishing line, after 5.6 years of clinical service.
MATERIALS AND METHODS
50 crowns (25 zirconia-based (Zr) and 25 porcelain-fused-to-metal (PFM)) were selected from 34 patients. The restorations were evaluated according to the California Dental Association (CDA) Quality Criteria, and periodontal variables were studied in the abutment teeth compared with the unrestored contralateral teeth. Variables were examined using Mann-Whitney and Pearson´s Chi-Square tests (α = 0.05). The success of the prosthesis was calculated using Kaplan-Meier test.
RESULTS
CDA Quality Criteria was considered satisfactory-excellent in all restorations except for one of them, due to chipping on a PFM crown. At, 66 months, the success rates for PFM and Zr crowns were 85.7% and 100%, respectively. The plaque index (PI) showed that the restored abutment teeth accumulated significantly less plaque than the control teeth, but the gingival index (GI) was statistically higher in the abutment teeth. In 80% of cases the probing depth (PB) was ≤ 3mm. In addition, in 21% of the cases, gingival recession was less than 2mm. The restoration material had a statistically significant effect on GI and PB, with Zr crowns showing less inflammation and less deep pockets than PFM restorations. On the contrary, greater gingival recession was found at the margins of the Zr crowns when compared to the PFM. No statistical differences were found between the two materials in the GI.
CONCLUSIONS
Cemented crowns on vertical preparations show good clinical behavior after 5 years. The periodontal parameters (PI, GI, PD) of the Zr restorations are significantly better than those of PFM, with the exception of gingival recession.
CLINICAL RELEVANCE
The use of restorations on vertically prepared teeth is a suitable alternative to classical horizontal preparations.
PubMed: 38554803
DOI: 10.1016/j.jdent.2024.104953 -
Journal of Personalized Medicine Feb 2024No systematic review or meta-analysis has been identified that provides a clinician's perspective on the shade selection process for ceramic restorations. The aim of the... (Review)
Review
BACKGROUND
No systematic review or meta-analysis has been identified that provides a clinician's perspective on the shade selection process for ceramic restorations. The aim of the present systematic review is to find and systematize the available knowledge by referring to the methods to assess the color of dental ceramics.
METHODS
The final search was performed on 10 December 2023 in six search engines. The keywords used in the search strategy were as follows: ("color matching" OR "shade matching" OR "color measurement" AND "porcelain" OR "dental ceramics") AND "dentistry" AND "accuracy".
RESULTS
The search strategy identified 139 potential articles. After the screening process, sixteen articles were included in the review.
CONCLUSIONS
In conclusion, the most common method, the visual method, has lower accuracy and repeatability. Devices like spectrophotometers and colorimeters provide precise, repeatable, and objective measurements, but fail to be widely applied in everyday clinical practice. Clinicians should not rely solely on their senses for shade determination, but should turn to quantitative methods. Colorimetric devices connected to mobile applications are an interesting and useful tool. Software and apps based on artificial intelligence are emerging as promising tools, but they require further research.
PubMed: 38540994
DOI: 10.3390/jpm14030252 -
Journal of Dentistry May 2024Natural teeth and dental restorations present with various shades and levels of translucency. This study aimed to determine whether these variations in ceramic crowns...
OBJECTIVES
Natural teeth and dental restorations present with various shades and levels of translucency. This study aimed to determine whether these variations in ceramic crowns and scan powder application affect the trueness of intraoral scanners.
METHODS
Eight identical premade resin typodonts, each prepared for a crown on the maxillary right second molar, were used. Eight lithium disilicate crowns, distinguished by two levels of translucency (high and low) and four shades (BL1, A2, A3, and A4), were fabricated to an identical design and cemented onto each typodont, providing eight distinct experimental groups (2 levels of translucency × 4 shades). Reference scans were acquired using a desktop scanner. Test scans were performed ten times for each experimental group using two different intraoral scanners (Medit i700 and CEREC Primescan AC), with and without the application of scan powder (n = 10). Three-dimensional metrology software was used to assess the trueness of the intraoral scan datasets. Statistical analysis involved the Kruskal-Wallis H test, Mann-Whitney U test, and independent t-test (α=0.05).
RESULTS
For powder-free intraoral scan datasets, the crown shade did not significantly affect trueness within each translucency group (P = 1.000). For both intraoral scanners, compared with low translucency groups, higher marked deviations were exhibited by high translucency groups (P<.001). Scan powder use largely mitigated these differences (P>.05) and enhanced the trueness of the intraoral scan (P<.01).
CONCLUSIONS
Shade did not significantly influence the trueness of intraoral scans. High-translucency crowns were scanned with less accuracy than were low-translucency crowns.
CLINICAL SIGNIFICANCE
Unlike tooth shade, translucency significantly affected the accuracy of intraoral scans. Therefore, considering the use of scan powder when scanning objects with high translucency may be beneficial.
Topics: Crowns; Humans; Dental Prosthesis Design; Dental Porcelain; Powders; Computer-Aided Design; Color; Prosthesis Coloring; Imaging, Three-Dimensional; Ceramics; Molar; Image Processing, Computer-Assisted
PubMed: 38537881
DOI: 10.1016/j.jdent.2024.104969 -
Brazilian Dental Journal 2024This study verified the effect of surface treatments of the zirconia-reinforced lithium disilicate ceramic bonded to resin cement. Ceramic blocks were divided according...
This study verified the effect of surface treatments of the zirconia-reinforced lithium disilicate ceramic bonded to resin cement. Ceramic blocks were divided according to treatments (n=10): FA+SRX (Fluoric acid + silane RX), FA+MDP (Fluoric acid + MDP), FA+SCF+MDP (Fluoric acid + silane CF + MDP), FA+MEP (Fluoric acid + MEP), and MEP (Self-etch primer). Resin cement cylinders were made in the ceramic blocks, photoactivated with 1,200 mW/cm² for 40s, stored in water at 37°C for 24h, and evaluated by the microshear strength test, optical failure descriptive analysis (%), surface characterization (SEM) and contact angle (Goniometer). Other samples were submitted to 10,000 thermocycles between 5°C and 55°C. Bond strength data were submitted to two-way ANOVA and Tukey's test. Contact angle to one-way ANOVA and Games-Howell's test (5%). At 24h, MEP showed higher bond strength, and FA+SRX the lower. FA+MDP and FA+SCF+MDP showed similar values and FA+MEP was intermediate. After thermocycling, FA+SCF+MDP, FA+MEP, and MEP showed higher values, and FA+SRX the lower while FA+MDP was intermediate. When the periods were compared, FA+MDP, FA+SCF+MDP, FA+MEP, and MEP showed higher values for 24h while FA+SRX was similar. SEM showed retentive surface and crystal exposure when treated with FA+SCF+MDP. The less retentive surface was obtained with MEP, and the other treatments promoted intermediate irregularities. In conclusion, surface treatment and thermocycling promoted different values of adhesive strength and contact angle in a zirconia-reinforced lithium silicate ceramic. Failures were predominantly adhesive, and the ceramic surface was characterized by different levels of roughness and selective exposure of crystals.
Topics: Resin Cements; Silanes; Dental Bonding; Surface Properties; Dental Porcelain; Ceramics; Zirconium; Materials Testing
PubMed: 38537020
DOI: 10.1590/0103-6440202405674 -
Brazilian Dental Journal 2024This study verified the effect of the combination of preheated hydrofluoric acid/silane/electric current in the adhesion of the resin cement to ceramic. IPS E.max Press...
This study verified the effect of the combination of preheated hydrofluoric acid/silane/electric current in the adhesion of the resin cement to ceramic. IPS E.max Press ceramic discs embedded in PVC rigid tubes were divided into four groups associating preheated hydrofluoric acid and silane applied with electrical current (n=10): Ha+S (Heated acid + silane); Ha+S+Ec (Heated acid + silane + electrical current); A+S (Acid + silane) and A+S+Ec (Acid + silano + electrical current). Resin cement/ceramic samples were stored in water at 37°C for 24h. After storage, they were submitted to the microshear test, fracture analysis, and contact angle at 24h or after thermocycling (10,000 cycles/5-55ºC). Bond strength data were evaluated by two-way ANOVA. For comparison between evaluation times (24h or thermocycling) was applied unpaired t-test. A significance post-hoc test of p=0.05 was assumed for analyses and graphs (GraphPad Prism 9.0 software). At 24h, the microshear strength showed similar values between Ha+S, Ha+S+Ec, and A+S+Ec groups, while A+S showed the lowest value with a statistical difference. After thermocycling, Ha+S and Ha+S+Ec were similar, as well as A+S and A+S+Ec. There was a significant difference in all groups comparing 24h (highest value) with after thermocycling (lowest value). Adhesive fracture was predominant in all groups and evaluation times. Ha+S and A+S groups showed higher contact angle values compared to the Ha+S+Ec and A+S+Ec with lower values. In conclusion, the association of preheated hydrofluoric acid/silane applied or not with electric current promoted different microshear strength values, fracture types, and contact angles in the resin cement/ceramic bond.
Topics: Resin Cements; Silanes; Hydrofluoric Acid; Surface Properties; Acid Etching, Dental; Dental Bonding; Ceramics; Dental Porcelain; Materials Testing
PubMed: 38537017
DOI: 10.1590/0103-6440202405641 -
Brazilian Dental Journal 2024This study investigated microshear bond strength (µSBS) of two (2) dual-cured resin-luting agents (RelyX™ Ultimate and RelyX™ U200) when photoactivated through...
This study investigated microshear bond strength (µSBS) of two (2) dual-cured resin-luting agents (RelyX™ Ultimate and RelyX™ U200) when photoactivated through varying thicknesses of lithium disilicate, with or without thermal cycling. Discs of IPS e.max Press of 0.5, 1.5, and 2 mm in thickness were obtained. Elastomer molds (3.0 mm in thickness) with four cylinder-shaped orifices 1.0 mm in diameter, were placed onto the ceramic surfaces and filled with resin-luting agents. A Mylar strip, glass plate, and load of 250 grams were placed over the filled mold. The load was removed and the resin-luting agents were photoactivated through the ceramics using a single-peak LED (Radii Plus.) All samples were stored in distilled water at 37oC for 24 h. Half of the samples were subjected to thermal cycling (3,000 cycles; 5ºC and 55ºC). All samples were then submitted to µSBS test using a universal testing machine (Instron 4411) at a crosshead speed of 0.5 mm/min. Data were submitted to three-way ANOVA and Tukey post-hoc test (α=0.05). The mean µSBS at 24 h was significantly higher than after thermal cycling (p<0.05). No statistical difference was found between resin-luting agents (p > 0.05). The mean µSBS for groups photoactivated through 0.5 mm ceramic were significantly higher than 1.5 mm and 2.0 mm (p < 0.05). In conclusion, increased ceramic thicknesses reduced the bond strength of tested resin-luting agents to lithium disilicate. No differences were found between resin-luting agents. Thermal cycling reduced the bond strength of both resin-luting agents.
Topics: Dental Bonding; Dental Porcelain; Ceramics; Resin Cements; Materials Testing; Surface Properties
PubMed: 38537015
DOI: 10.1590/0103-6440202405619