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1.
J Prosthet Dent ; 2021 Feb 04.
Artículo en Inglés | MEDLINE | ID: mdl-33551133

RESUMEN

STATEMENT OF PROBLEM: Tissue-level internal connection implants are widely used, but the difference in abutment screw stability because of the shoulder coverage formed by the contact between the shoulder of the implant collar and the abutment remains unclear. PURPOSE: The purpose of this finite element analysis (FEA) and in vitro study was to investigate stress distribution and abutment screw stability as per the difference in shoulder coverage of the abutment in tissue-level internal connection implants. MATERIAL AND METHODS: Abutments were designed in 3 groups as per the shoulder coverage of the implant collar, yielding complete coverage (complete group), half coverage (half group), no coverage (no group) groups. In the FEA, a tightening torque of 30.0 Ncm was applied to the abutment screw, a force of 250 N was applied to the crown at a 30-degree angle, and the von Mises stresses and the stress distribution patterns were evaluated. In the in vitro study, the groups were tested (n=12). A total of 200 000 cyclic loads were applied at 250 N, 14 Hz, and at a 30-degree angle. Removal torque values and scanning electron microscopy (SEM) images were assessed. Removal torque values were analyzed by ANOVA and paired t tests. RESULTS: The maximum von Mises stress of the abutment screw was the lowest in the complete group, slightly higher in the half group, and highest in the no group. High stresses were concentrated in 1 location in the implant abutment connection area of the no group. The removal torque values after loading were significantly lower in the no group than in the complete group (P=.047). The SEM images revealed concentrated structural loss and wear in 1 location of the no group. CONCLUSIONS: FEA and in vitro studies confirmed that the shoulder coverage of the abutment in the tissue-level internal connection implant helped improve screw stability. Cyclic loading reduced the removal torque of the abutment screw.

2.
J Prosthet Dent ; 2021 Feb 11.
Artículo en Inglés | MEDLINE | ID: mdl-33583617

RESUMEN

STATEMENT OF PROBLEM: Studies evaluating the accuracy of edentulous arch impressions encompassing conventional and digital methods are lacking. PURPOSE: The purpose of this in vitro study was to evaluate 8 impression-making methods for edentulous arches and to determine the effects of using a 3-dimensionally printed polyetheretherketone (PEEK) scanning aid on the accuracy of intraoral scanners. MATERIAL AND METHODS: Three sets of edentulous arch typodonts were scanned with an industrial scanner as a reference. Subsequently, a scanning aid for the edentulous arch was individually designed on each reference scan dataset by using a 3-dimensional modeling software program and fabricated in PEEK with a 3-dimensional printer. Each typodont was scanned with 2 intraoral scanners 12 times, with and without the assistance of a scanning aid for the edentulous arch. Impressions were made with 4 different conventional impression materials (irreversible hydrocolloid, polysulfide, polyether, and polyvinyl siloxane)-12 times for each typodont-the casts were poured and digitized with a tabletop scanner. Each scan data set was superimposed over the corresponding scan data set, and the original and absolute distance values from the paired surface points were obtained to measure the trueness and precision. These were expressed by using the mean, median, root mean square, and (90 percentile-10 percentile)/2 of the absolute distance value (NMT) concepts, based on the raw data extraction protocol. A repeated-measures ANOVA followed by a post hoc Bonferroni test was conducted (α=.05). RESULTS: The impression-making methods did not show statistically significant differences (P>.05) for either trueness or precision, particularly when the median values of the original and absolute distance values from the paired surface points were chosen as the standard values. One of the intraoral scanners used exhibited significantly superior outcomes to conventional impression materials when scanned with the scanning aid for the edentulous arch for both trueness and precision when the mean, root mean square, and NMT concepts were applied (P<.05). CONCLUSIONS: Intraoral scanners demonstrated accuracy comparable with that of conventional impression materials for making edentulous arch impressions, regardless of the concepts used to express the trueness and precision. The PEEK-based scanning aid for the edentulous arch did not improve the accuracy of the intraoral scanners; however, its application resulted in higher accuracy compared with that of conventional impression materials.

3.
Materials (Basel) ; 13(23)2020 Nov 28.
Artículo en Inglés | MEDLINE | ID: mdl-33260676

RESUMEN

The amount of photopolymer material consumed during the three-dimensional (3D) printing of a dental model varies with the volume and internal structure of the modeling data. This study analyzed how the internal structure and the presence of a cross-arch plate influence the accuracy of a 3D printed dental model. The model was designed with a U-shaped arch and the palate removed (Group U) or a cross-arch plate attached to the palate area (Group P), and the internal structure was divided into five types. The trueness and precision were analyzed for accuracy comparisons of the 3D printed models. Two-way ANOVA of the trueness revealed that the accuracy was 135.2 ± 26.3 µm (mean ± SD) in Group U and 85.6 ± 13.1 µm in Group P. Regarding the internal structure, the accuracy was 143.1 ± 46.8 µm in the 1.5 mm-thick shell group, which improved to 111.1 ± 31.9 µm and 106.7 ± 26.3 µm in the roughly filled and fully filled models, respectively. The precision was 70.3 ± 19.1 µm in Group U and 65.0 ± 8.8 µm in Group P. The results of this study suggest that a cross-arch plate is necessary for the accurate production of a model using 3D printing regardless of its internal structure. In Group U, the error during the printing process was higher for the hollowed models.

4.
Materials (Basel) ; 13(19)2020 Oct 04.
Artículo en Inglés | MEDLINE | ID: mdl-33020417

RESUMEN

To assess the accuracy of various intraoral scanners (IOSs) and to investigate the existence of mutual compatibility that affects the accuracy between IOS and 3-dimensional (3D) printing using a scan quadrant model. For clinical implication, crown preparations and cavity design according to prosthetic diagnosis and treatment considerations must be acquired by a digital scanner. The selected typodont model was scanned using a reference scanner, from which reference (Ref) standard tessellation language (STL) data were created. Data obtained by scanning the typodont model with IOSs based on three different technologies were divided into three groups (CS3600, i500, and Trios3). Scanned data from the groups were divided into sub-groups of digital light processing (DLP), fused deposition modeling (FDM), and stereolithography apparatus (SLA), based on which 3D printed models (3DP) were fabricated. The 3DP dental models were scanned to obtain a total of 90 3DP STL datasets. The best-fit algorithm of 3D analysis software was used for teeth and arch measurements, while trueness was analyzed by calculating the average deviation among measured values based on superimposition of Ref and IOS and 3DP data. The differences between Ref and IOS (Ref-IOS), Ref and 3DP (Ref-IOS/3DP), and IOS and 3DP data (IOS-3DP) were compared and analyzed, while accuracy within each of the three main groups was assessed. For statistical analysis, the Kruskal-Wallis, Mann-Whitney U, and repeated measures ANOVA test were used (p < 0.05). The major finding is that the mutual relationships between IOSs and 3D printers vary depending on the combination. However, i500 intraoral scanner and DLP 3D printer was the combination that showed the best trueness value.

5.
Polymers (Basel) ; 12(6)2020 Jun 22.
Artículo en Inglés | MEDLINE | ID: mdl-32580368

RESUMEN

Esthetic dental computer-aided design/computer-aided manufacturing (CAD/CAM) polymers such as disperse-filled composites (DFC) and polymer-infiltrated ceramic networks (PICN) should be subjected to surface treatment before bonding. However, such treatment can lead to defect formation and a decrease in strength. Therefore, in this study, we compared the flexural strengths of DFC and PICN materials air-abraded with alumina particles of different sizes at different pressures. In addition to Weibull analysis, the samples (untreated and treated) were characterized by scanning electron microscopy and atomic force microscopy. Both DFC and PICN exhibited the lowest flexural strength at large particle sizes and high pressures. Therefore, we optimized the air abrasion parameters to maintain the flexural strength and significantly increase surface roughness. In the case of DFC, the optimal particle size and pressure conditions were 50 µm at 2 bar and 110 µm at 1 bar, while for PICN, the best performance was obtained using Al2O3 particles with a size of 50 µm at 1 bar. This study reveals that optimization of the surface treatment process is crucial in the fabrication of high-performance clinical materials for dental restorations.

6.
J Prosthet Dent ; 124(6): 816-817, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-32389378
7.
Materials (Basel) ; 13(6)2020 Mar 20.
Artículo en Inglés | MEDLINE | ID: mdl-32244878

RESUMEN

This study evaluated the shear bond strength (SBS) and biaxial flexural strength (BFS) of resin cements according to the surface treatment method using low-temperature hot etching with hydrofluoric acid (HF) on a yttrium-stabilized tetragonal zirconia (Y-TZP) surface; 96 discs and 72 cubes for BFS and SBS tests for Y-TZP were randomly divided into four groups of BFS and three groups of SBS. Specimens were subjected to the following surface treatments: (1) no treatment (C), (2) air abrasion with 50 µm Al2O3 particles (A), (3) hot etching with HF at 100 °C for 10 min (E), and (4) air abrasion + hot etching (AE). After treatments, the specimens were coated with primer, and resin cement was applied with molds. The specimens were evaluated for roughness (Ra) via scanning electron microscopy and x-ray diffraction, and the data were analyzed by an analysis of variance (ANOVA) and Kruskal-Wallis tests. Group E produced significantly higher SBS compared to group A and AE before and after thermocycling. The BFSs of all groups showed no significant differences before thermocycling; however, after thermocycling, C and E treatment groups were significantly higher compared to group A and AE. All groups showed phase transformation. Group E was observed lower monoclinic phase transformation compared to other groups.

8.
J Prosthet Dent ; 2020 Apr 21.
Artículo en Inglés | MEDLINE | ID: mdl-32331784

RESUMEN

This article describes a combined conventional and digital workflow for fabricating removable partial dentures (RPDs). After scanning the dental cast and RPD framework assembly, artificial teeth and denture base regions were designed using computer-aided design software. The artificial teeth and denture base assembly was milled as a single structure by using a wax disk and then placed on the RPD framework. The artificial teeth were additionally milled from a polymethyl methacrylate disk. Conventional procedures were followed for denture investment until the wax elimination procedure, after which the assembly was replaced with the artificial teeth in the cope of the flasks, and the denture resin material was injected to process the RPD. This technique enabled the RPD to be fabricated in the same form as the design state.

9.
J Prosthet Dent ; 2020 Feb 04.
Artículo en Inglés | MEDLINE | ID: mdl-32033790

RESUMEN

A facebow transfer is typically used for mounting a maxillary gypsum cast in an ideal location in a mechanical articulator. However, the facebow transfer procedure is difficult and may cause the patient discomfort. This proposed technique uses a patient's cone beam computed tomography (CBCT) data to reproduce the occlusal plane in relation to digital articulator scan data, align the patient's gypsum cast or intraoral scan data on the reproduced plane, and then transfer the data to a mechanical articulator.

10.
J Prosthet Dent ; 124(2): 157-160, 2020 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-31753463

RESUMEN

A digital workflow to assess the soft tissue dimensional changes in completely edentulous patients is described. Diagnostic casts obtained at 2 time points and the complete denture were scanned by using a desktop scanner. The denture scan was inverted by using a metrology software program to obtain the soft tissue contour. Using this reversed file as a reference, the file and 2 scan files obtained at different time points were aligned individually with the best fit alignment function. The scanned denture file and the 2 realigned scan files were imported into the same software. A plane vertical to the occlusal plane was determined such that it moved anteroposteriorly. The distance between the contours of the 2 realigned files was measured by selecting a point and a vector based on the artificial tooth positions of the denture. This technique of using a reversed denture file may provide a quantitative evaluation of soft tissue changes and further aid in determining appropriate intervals for denture relining or rebasing.


Asunto(s)
Boca Edéntula , Diente Artificial , Dentadura Completa , Humanos , Programas Informáticos
11.
J Prosthet Dent ; 123(3): 531-534, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31307800

RESUMEN

To simulate the current oral status of patients, including maxillofacial defects, the digital method described uses a method based on multisource data. These include data recorded from scans made with and without wearing an obturator and data obtained by scanning the surgical or interim obturator. This method eliminates the need for preliminary impressions and complex border-molding steps during the process of creating a definitive obturator, thereby greatly simplifying the fabrication process.


Asunto(s)
Implantes Dentales , Obturadores Palatinos , Humanos , Boca
12.
J Prosthet Dent ; 123(3): 384-388, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31307802

RESUMEN

During production of an immediate interim implant-supported fixed restoration with interim cylinders, the formation of an access hole in the dentures is critical. Traditional access hole formation involves repeated prosthesis insertion and removal in the oral cavity, primarily through trial and error, to adjust the hole position and size. The presented technique simulates the interim cylinder position based on the healing abutment position, enabling confirmation of the access hole position and ensuring more precise seating of the interim implant-supported fixed restoration.


Asunto(s)
Implantes Dentales , Diseño de Prótesis Dental , Prótesis Dental de Soporte Implantado , Dentaduras
13.
Materials (Basel) ; 12(22)2019 Nov 16.
Artículo en Inglés | MEDLINE | ID: mdl-31744164

RESUMEN

The purpose of this study was to evaluate the change in the retentive forces of four different titanium-based implant attachment systems during the simulation of insert-removal cycles in an artificial oral environment. Five types of titanium-based dental implant attachment systems (Locator, Kerator, O-ring, EZ-Lock, and Magnetic) were studied (n = 10). The specimens underwent insert-removal cycles in artificial saliva, and the retentive force was measured following 0, 750, 1500, and 2250 cycles. Significant retention loss was observed in all attachment systems, except the magnetic attachments, upon completion of 2250 insertion and removal cycles, compared to the initial retentive force (p < 0.05). A comparison of the initial retentive forces revealed the highest value for Locator, followed by the Kerator, O-ring, EZ-Lock, and Magnetic attachments. Furthermore, Kerator demonstrated the highest retentive loss, followed by Locator, O-ring, EZ-Lock, and Magnetic attachments after 2250 cycles (p < 0.05). In addition, the Locator and Kerator systems revealed significant decrease in retentive forces at all measurement points (p < 0.05). The retention force according to the insert-removal cycles were significantly different according to the types of dental implant attachment systems.

14.
Antonie Van Leeuwenhoek ; 112(11): 1699-1704, 2019 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-31267336

RESUMEN

A yellow-pigmented bacterial strain, GS03T, was isolated from sediment in a branch of the Nackdong River in Sangju, Korea. Cells were observed to be Gram-negative, aerobic and rod-shaped with gliding motility, and to be positive for catalase and oxidase. Growth was found to occur at 4-30 °C (optimum 25 °C), at pH 7.0-8.5 (optimum pH 7.5) and at NaCl 0% (optimum NaCl 0%, w/v). The major cellular fatty acids (> 10% of the total) were identified as iso C15:0, iso C15:1 G, C15:1ω6c, iso C15: 0 3-OH and iso C17: 0 3-OH. The major respiratory quinone was found to be menaquinone MK-6. The genome sequence of GS03T is 3.1 Mb with G+C content of 36.1 mol%. The major polar lipids of the isolate were identified as phosphatidylethanolamine, three unidentified aminolipids, two unidentified phospholipids, an unidentified lipid and an unidentified aminophospholipid. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain GS03T clusters with Flavobacterium paronense KNUS1TT, with similarity of 96.8%. The phenotypic, phylogenetic, and chemotaxonomic characteristics indicate that strain GS03T represents a novel species of the genus Flavobacterium, for which the name Flavobacterium sangjuense sp. nov. is proposed. The type strain is GS03T (= FBCC 502459T = KCTC 62568T = JCM 32764T).


Asunto(s)
Flavobacterium/clasificación , Flavobacterium/aislamiento & purificación , Sedimentos Geológicos/microbiología , Microbiología del Suelo , Ácidos Grasos/química , Flavobacterium/química , Genoma Bacteriano , Genómica/métodos , Fenotipo , Filogenia , ARN Ribosómico 16S/genética , República de Corea
15.
J Prosthodont ; 28(7): 797-803, 2019 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-31250506

RESUMEN

PURPOSE: To determine the accuracy of a digital manufacturing method for dental implant restorations on stock abutments using intraoral scanners and prefabricated stock-abutment libraries. MATERIALS AND METHODS: Two dental implants with internal hexagonal connections were placed in the mandibular second premolar and second molar areas of a partially edentulous dentoform model; stock abutments with a diameter of 5 mm, abutment height of 5.5 mm, and gingival cuff height of 2 mm were connected. The study model was scanned 10 times using a reference tabletop scanner and 5 types of intraoral scanners (IOSs). The data collected by 5 types of IOSs were divided into 3 groups, based on the type and matching of stock abutment library data: no library, optical library, and contact library groups. A total of 160 data files were analyzed, including reference data. The resulting data were used to evaluate trueness and precision. RESULTS: Trueness and precision values in the group in which library data of the stock abutment were not used were 42.0 to 76.3 µm and 30.5 to 99.7 µm; corresponding values when the library data using an optical scanner were matched were 51.2 to 73.4 µm and 26.3 to 62.8 µm, and those when contact scanner library data were used were 30.1 to 62.4 µm and 15.5 to 55.9 µm. Thus, the accuracy of the contact library group was significantly higher than the accuracies of the no library (p < 0.001) and optical library groups (p < 0.001). CONCLUSION: The application of prefabricated library data of stock abutments using a contact scanner improved the accuracy of scan data. Scan accuracy of the stock abutments differed significantly based on the type of scanner.


Asunto(s)
Implantes Dentales , Boca Edéntula , Diseño Asistido por Computadora , Pilares Dentales , Técnica de Impresión Dental , Humanos
16.
Int J Syst Evol Microbiol ; 69(6): 1546-1550, 2019 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-30932804

RESUMEN

A Gram-stain-negative, catalase- and oxidase-positive, non-motile bacterium, designated F02T, was isolated from of gut of Cincticostellalevanidovae (Tshernova). Growth occurred at a temperature range of 4-30 °C, at pH 6-9 and in the presence of 0-0.5 % (w/v) NaCl. Phylogenetic analysis demonstrated that the 16S rRNA gene sequence of strain F02T shared the highest similarity to that of the type strain of Hydromonas duriensis A2P5T (96.82 %). The major isoprenoid quinone was Q-8. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The major cellular fatty acids were summed feature 3 (C16 : 1ω7c/C16 : 1ω6c) and iso-C13 : 0 3-OH. The polyamines were cadaverine and putrescine. Combined data from phylogenetic, phenotypic and chemotaxonomic analyses demonstrated that strain F02T represents a novel genus and species, for which the name Ephemeroptericolacinctiostellae gen. nov., sp. nov. is proposed. The type strain of Ephemeroptericola cinctiostellae gen. nov., sp. nov. is F02T (=FBCC 500047T=KCTC 62567T=JCM 32722T).


Asunto(s)
Burkholderiaceae/clasificación , Tracto Gastrointestinal/microbiología , Insectos/microbiología , Filogenia , Animales , Técnicas de Tipificación Bacteriana , Composición de Base , Burkholderiaceae/aislamiento & purificación , ADN Bacteriano/genética , Ácidos Grasos/química , Fosfolípidos/química , Poliaminas/química , ARN Ribosómico 16S/genética , República de Corea , Análisis de Secuencia de ADN
17.
J Clin Med ; 8(4)2019 Apr 11.
Artículo en Inglés | MEDLINE | ID: mdl-30978960

RESUMEN

Limited evidence is available comparing the differences between pre-operative and post-operative 3D implant positions from the viewpoint of prosthetics. We aimed to investigate the differences between preplanned positions of virtual provisional restorations and their actual positions following fully guided single-implant placement. Ten maxillary typodonts with missing right central incisors were imaged using cone-beam computed tomography, and digital impressions were obtained using an intraoral scanner. These data were imported into implant-planning software, following which the provisional restorations were designed. After data superimposition, an appropriate implant position was determined, and a computer-assisted implant surgical guide was designed for each typodont. Orders generated from the implant-planning software were imported into relevant computer-aided design software to design the custom abutments. The abutments, provisional restorations, and surgical guides were fabricated, and each restoration was cemented to the corresponding abutments, generating a screw-type immediate provisional restoration. The implants were placed using the surgical guides, and the screw-type provisional restorations were engaged to the implants. The typodonts were then rescanned using the intraoral scanner. The restorations designed at the treatment planning stage were compared with those in the post-operative scan using metrology software. The angular deviation around the central axis of the implant was measured, and the differences in the crown position were converted to root mean square (RMS) values. The post-operative provisional restorations exhibited an absolute angular deviation of 6.94 ± 5.78° and an RMS value of 85.8 ± 20.2 µm when compared with their positions in the pre-operative stage. Within the limitations of the present in vitro study, the results highlight the potential application of customized prefabricated immediate provisional restorations after single-implant placement.

18.
J Clin Med ; 8(4)2019 Mar 28.
Artículo en Inglés | MEDLINE | ID: mdl-30925756

RESUMEN

This report describes the case of a patient who required rehabilitation of their maxillary anterior teeth following a traumatic injury through a physical altercation. The decision was made to extract the maxillary central incisors and maxillary right lateral incisor, perform immediate implantation on the maxillary right lateral incisor and left central incisor areas, and place a three-unit immediate provisional restoration. Predesigned virtual teeth enabled efficient fabrication of the immediate provisional restoration following the implant placement. After a sufficient healing period with periodic check-ups, final impressions were made using a digital approach, with meticulous care taken to preserve the gingival architecture around the sites of rehabilitation. Thus, the custom abutments and definitive restoration were placed without eliciting an uncomfortable feeling in the patient. Both esthetic and functional outcomes were satisfactory. Reduced soft tissue volume around the implant restoration was observed, primarily within the two months post-extraction/implantation, based on superimposition of the serial scan data. Soft tissue volume changes in the present case suggest the need for controlled clinical studies of three-dimensional changes of gingival contours after extraction and/or implantation.

19.
Dent Mater ; 35(3): 468-476, 2019 03.
Artículo en Inglés | MEDLINE | ID: mdl-30685109

RESUMEN

OBJECTIVES: The aim of the present study was to investigate the adaptation and guide hole tolerance of metal sleeve-free computer-assisted implant surgical guides fabricated with 3D printers. METHODS: An implant surgical guide for full-guided implant placement was designed with a total of eight different guide holes. Ten implant surgical guides (n=10) were fabricated from the same design with each of five in-office 3D printers (D1, FOR, ONE, PER, and ZEN) using compatible printing materials. Ten surgical guides fabricated by the manufacturer of the implant company were used as the control group (CON). The adaptation of the surgical guides was evaluated by the replica technique. The tolerance of the guide holes was evaluated by measuring the degree of diversion with guide drills. RESULTS: CON and D1 showed superior internal adaptation with a gap distance of less than 1mm. The mean degree of diversion of the guide holes ranged from 3.45° for ZEN to 6.55° for PER. The tolerances of CON (4.70°) and D1 (4.50°) did not differ at the level of statistical significance at α=0.05. SIGNIFICANCE: The characteristics of implant surgical guides were evaluated per se. None of the 3D printers fabricated superior implant surgical guides to those produced by the manufacturer with regard to the internal fit and guide tolerance. However, the potential for the routine clinical use of in-office 3D printers was demonstrated. Further studies are required to determine how the guide hole tolerance and the angular deviation between the preplanned and actual implant positions are related.


Asunto(s)
Implantación Dental Endoósea , Cirugía Asistida por Computador , Diseño Asistido por Computadora , Imagenología Tridimensional , Metales , Impresión Tridimensional
20.
J Prosthet Dent ; 121(3): 417-425, 2019 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-30391060

RESUMEN

STATEMENT OF PROBLEM: Zirconia is a widely used restorative material. However, phase transformation on clinical application of zirconia has not yet been studied. PURPOSE: The purpose of this study was to evaluate the wear, surface roughness, and aging associated with polished translucent zirconia in both in vitro and clinical experiments. MATERIAL AND METHODS: In vitro experiments were performed with Rainbow and Katana zirconia blocks and natural tooth enamel as the control. They were subjected to 100 000 loading cycles with a maxillary premolar antagonist. All specimens were analyzed for wear, and the zirconia specimens were evaluated for surface roughness and monoclinic phase (m-phase) transformation by X-ray diffractometry before and after cyclic loading. The clinical study included participants who required single-crown implant-supported restorations replacing the first or second molar. The participants received Rainbow or Katana zirconia prostheses (n=15, each). For wear analysis, impressions of each prosthesis, antagonist, and adjacent tooth were made at 1 week and 6 months after crown delivery. The occlusal relationship of the crowns in maximum intercuspation was evaluated by using the T-Scan 8 occlusal diagnostic system. The degree of transformation of zirconia to the m-phase was measured by using X-ray diffractometry of the crowns after 6 months of use. RESULTS: Zirconia induced significantly greater enamel wear than the natural tooth control. Katana specimens exhibited significantly greater wear and surface roughness than the Rainbow specimens. The degrees of antagonistic wear and zirconia phase transformation in the clinical experiment were significantly greater than those in the in vitro experiment. The Katana groups showed significantly higher m-phase levels than the Rainbow groups. CONCLUSIONS: Phase transformation of zirconia occurs within 6 months of clinical use, and the wear and degrees of phase transformation varied according to the zirconia product used.


Asunto(s)
Alisadura de la Restauración Dental , Circonio , Esmalte Dental , Ensayo de Materiales , Propiedades de Superficie
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