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1.
Int J Comput Dent ; 27(1): 27-35, 2024 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-36928756

RESUMO

AIM: The present in vitro study aimed to evaluate the depth of reading of intraoral scanners (IOSs) within the gingival sulcus. MATERIALS AND METHODS: A knife-edge preparation for a full crown was performed on a Frasaco model. The gingival sulcus of the scanned model was modified using a dedicated software program (Model Creator, exocad DentalCAD 2.4 Plovdiv) by setting the apical width (AW), coronal width (CW), and gingival sulcus depth (D). Two dental models with different gingival sulcus depths (1 or 2 mm) were printed using the digital light processing (DLP) technique. Each model was scanned 10 times. Seven different IOSs were used: Emerald, Trios 3, Carestream 3600, Dental Wings DWIO, CondorScan, True Definition Scanner (TDS), and Cerec Omnicam. Measurements of D values were performed using 3Shape 3D viewer software. The normality of the data distribution was evaluated using the Shapiro-Wilk test (P < 0.05). The nonparametric Levene's test was used to check for homoscedasticity. The data were statistically analyzed using the Kruskal-Wallis test (α = 0.05) and the Nemenyi test. RESULTS: All IOSs were able to read within the 1-mm-deep gingival sulcus, albeit with some statistically significant differences (P < 0.001). TDS and Trios 3 were able to read within the 2-mm-deep gingival sulcus (P < 0.001). CONCLUSIONS: The depth of reading of different IOSs can vary significantly. In the model with a 2-mm gingival sulcus, even in the absence of oral fluids, the depth of reading was incomplete, suggesting that deep preparations into the gingival sulcus are difficult to detect with IOSs.


Assuntos
Imageamento Tridimensional , Leitura , Humanos , Técnica de Moldagem Odontológica , Desenho Assistido por Computador , Modelos Dentários , Arco Dental
2.
Clin Oral Investig ; 27(11): 6567-6575, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37749286

RESUMO

OBJECTIVES: To evaluate the clinical performance of monolithic zirconia restorations with feather-edge margins fabricated by digital impressions. MATERIALS AND METHODS: All participants that present monolithic zirconia restorations with feather-edge margins realized with digital workflow were evaluated during scheduled periodontal maintenance between February and September 2022 according to predetermined inclusion criteria. Clinical performance was assessed using the modified USPHS and periodontal parameters. Overall survival was calculated for monolithic zirconia restorations. Technical and biologic complications were reported. Descriptive statistical analysis and life-table analyses were performed for all data. RESULTS: A total of 1472 monolithic zirconia FDPs (1279 on abutments and 193 on pontics) placed in 1189 patients (982 males and 490 females) from February 2017 to September 2020 were analyzed. The mean follow-up was 44 months (range 36-61 months), and the overall survival rate was 98.5%. There were 931 single crowns, 96 were 3-unit FDPs, 33 were 4-unit FDPs, 11 were 5-unit FDPs, and 6-unit FDPs. Three single crowns had irreparable cracks, and 6 single crowns and one 4-unit FDP were fractured. One 3-unit FDP failed due to tooth fracture and 5 single crowns failed due to endodontic failure. The loss of retention was noted in 25 monolithic zirconia FDPs and hypersensitivity in 44 single crowns. Biologic complications were uncommon. CONCLUSIONS: Based on the results and its limitations, the monolithic zirconia FPDs and digital impressions represent a favorable prosthetic treatment similar to that reported with other margin designs CLINICAL RELEVANCE: Monolithic zirconia restorations on vertical-margin abutments fabricated using a digital workflow demonstrate excellent clinical performance. The digital clinical workflow without the use of a cast means a reduction in costs, steps, and operating time.


Assuntos
Produtos Biológicos , Coroas , Masculino , Feminino , Humanos , Estudos Retrospectivos , Fluxo de Trabalho , Zircônio , Falha de Restauração Dentária , Desenho Assistido por Computador
3.
J Prosthet Dent ; 129(4): 566-572, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-34344529

RESUMO

STATEMENT OF PROBLEM: The choice of retention type of an implant-supported fixed dental prosthesis (FDP) becomes critical when the dental implant is not placed in a prosthetically ideal location. In recent years, computer-aided design and computer-aided manufacturing (CAD-CAM) technology has enabled the correction of the location of screw access hole depending on the clinical needs of the patient. However, how FPDs with angulated screw channels (ASCs) perform clinically is unclear. PURPOSE: The purpose of this prospective clinical study was to evaluate the mechanical complications and crestal bone loss (CBL) when posterior monolithic zirconia implant-supported FDPs with an ASC are used. MATERIAL AND METHODS: Participants (N=37) with a missing single posterior tooth or multiple teeth, sufficient bone height, and an implant site without infection were included. Each participant received parallel-walled implants (Nobel Parallel CC) of 7-, 8.5-, or 10-mm length by using a 1-stage approach. After 4 months of healing, a conventional impression was made, and a digital workflow was followed. Monolithic zirconia restorations (Katana ML) were milled, stained, and mechanically attached to a titanium base (NobelProcera ASC abutment). CBL was measured from radiographs at 6, 12, 24, and 36 months after the placement of the prosthesis. Implant and prosthetic characteristics including implant diameter, implant length, screw channel angle (angle≤15 degrees versus angle>16 degrees), prosthetic type (single crown versus multiple-unit FDP), and antagonist dentition (natural versus prosthesis) were also recorded. A generalized linear mixed model with a log link was estimated to assess the independent predictors of CBL among the angles of ASC-retained definitive restorations and the clinically relevant variables (α=.05). RESULTS: Thirty-seven participants received 51 implants, and the median follow-up period was 30 months (interquartile range: 22-36). Two single-crown implants failed within the first 12 months of delivery. The implant and restoration survival rate was 96% at 36 months. Screw loosening was recorded in 2 study participants. After a follow-up of 36 months, the mean ±standard deviation CBL value was 0.15 ±0.14 mm with an increase over time (P<.001). The effect of the angle of ASC, implant diameter, implant length, prosthetic type, and antagonist on the CBL was not statistically significant (P>.05). CONCLUSIONS: CBL was not associated with the angle of ASC, implant diameter, implant length, prosthetic type, or antagonist when posterior monolithic zirconia implant-supported FDPs with ASCs were used. Screw loosening in 2 situations was the only mechanical complication during the first 3 years of service.


Assuntos
Prótese Dentária Fixada por Implante , Zircônio , Humanos , Estudos Prospectivos , Parafusos Ósseos
4.
Clin Chem Lab Med ; 60(6): 886-890, 2022 05 25.
Artigo em Inglês | MEDLINE | ID: mdl-35218178

RESUMO

OBJECTIVES: The observation of numerous new structural defects in hemoglobin (Hb) has often been linked to the evolution and development of device technologies used for the separation and quantification of hemoglobin components. However, the increased use of preventive tests for hemoglobinopathies and separative methods to quantify glycated hemoglobin (HbA1c) also contributed to these observations, as demonstrated by the case described here. Our aim is to emphasize that different separative method can provide more useful information in patient management. METHODS: A 64-year-old diabetic woman of Moroccan descent was examined in the context of HbA1c monitoring. The test was performed using high performance liquid chromatography (HPLC) and capillary electrophoresis (CE) systems. Molecular characterization was performed by direct sequencing of the ß and α globin genes. RESULTS: The two methods used showed the presence of an anomalous fraction identified as HbS, already observed previously, but only through CE it was possible to observe the presence of another variant and its hybrid components. Direct sequencing of ß and α globin genes confirmed heterozygous HbS [ß6 (A3) Glu→Val; HBB: c.20A>T] and allowed to identify a mutation on the α2, [α114 (GH2) Pro→Leu gene; HBA2: c.344C>T] corresponding to the rare Hb Nouakchott variant. CONCLUSIONS: The two Hb variants highlighted by the EC and the molecular characterization therefore allowed adequate advice, the correct assessment of HbA1c and metabolic status and therefore better clinical management of the patient. The availability of different instruments in the same laboratory, confirming situations of diagnostic uncertainty, represents a valuable opportunity that should be encouraged.


Assuntos
Hemoglobinopatias , Hemoglobinas Anormais , Cromatografia Líquida de Alta Pressão , Eletroforese Capilar/métodos , Feminino , Hemoglobinas Glicadas/análise , Hemoglobinas Glicadas/genética , Hemoglobinopatias/diagnóstico , Hemoglobinopatias/genética , Hemoglobinas Anormais/análise , Humanos , Pessoa de Meia-Idade , Mutação , alfa-Globinas/genética
5.
J Prosthodont ; 30(2): 104-110, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33009865

RESUMO

PURPOSE: Reconstructing the occlusal morphology of posterior teeth in definitive dental prosthesis can be challenging. The use of the correlation technique enables replication of the information and occlusal anatomy of interim dental prostheses to the definitive ones. The purpose of this controlled clinical trial was to compare the static and dynamic contacts (SDC) of monolithic zirconia crowns designed with correlation and library techniques. MATERIAL AND METHODS: Twenty-four patients were included in the study for a total of 28 molars. For each abutment tooth, an interim crown was fabricated and two digital scans, with and without the interim crown in place were made. Two single crowns were designed using correlation and library techniques. Fifty-six monolithic zirconia crowns were milled. The interim and definitive crowns were evaluated intraorally for SDC by using a 24-µm-thick blue articulating foil. After removing the interim and definite crowns, extraoral photographs were taken to calculate the SDC area using software (ImageJ) and analyzed by the Kruskal-Wallis test. RESULTS: The average and ± standard deviation (SD) of area of the occlusal marks on interim crowns was 32.27 ± 3.45 mm2 . Definitive crowns designed by using the correlation technique had an area of 31.01 ± 3.73 mm2 ; the area in the library technique was 36.85 ± 5.78 mm2 . No statistically significant difference was found (p = 0.091) between the occlusal mark areas of the interim and definitive crowns designed by using the correlation technique. Whereas, there were significant differences between the areas of occlusal marks of the interim and definitive crowns designed by using the library technique, and between the areas of occlusal marks of definitive crowns designed by using the correlation and library techniques (p < 0.001). CONCLUSION: The average area of the SDC of monolithic zirconia crowns designed by using the correlation technique was similar to that of interim crowns. The library technique was less effective when replicating the SDC compared to the correlation technique.


Assuntos
Planejamento de Prótese Dentária , Técnicos em Prótese Dentária , Desenho Assistido por Computador , Coroas , Porcelana Dentária , Humanos , Zircônio
6.
J Prosthet Dent ; 124(6): 787.e1-787.e8, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33041073

RESUMO

STATEMENT OF PROBLEM: The effect of prophylactic polishing pastes on composite resin materials has been extensively investigated, but little is known about their effect on ceramic materials. PURPOSE: The purpose of this in vitro study was to evaluate the effect of prophylactic polishing pastes on the 2D and 3D roughness, translucency, and gloss of different ceramic materials. MATERIAL AND METHODS: A total of 120 flat specimens (thickness: 2 mm) obtained from computer-aided design and computer-aided manufacturing (CAD-CAM) blocks of leucite glass-ceramic (Empress CAD), lithium disilicate glass-ceramic (e.max CAD), and zirconia (Zenostar MT) were glazed and sintered. Forty specimens from each material were then divided into 4 groups and polished with Cleanic fine, Nupro fine, or Proxyt fine pastes, leaving the control group untreated. The specimens were polished for 2 minutes with a prophylaxis cup mounted on a handpiece, applying a constant load of 3.9 N at 2000 rpm. Surface roughness was measured by using a contact profilometer and a 3D optical profilometer. The translucency parameter and gloss value were calculated by using a spectrophotometer and a glossmeter. One specimen per group was observed by scanning electron microscopy at ×200 magnification. Differences in means were compared by using 2-way ANOVA followed by the Tukey honestly significant difference (HSD) test (α=.05). RESULTS: The 2D roughness of Empress was lower than that of e.max (P<.05) and was increased by using Cleanic fine and Nupro fine pastes (P<.05). The translucency parameter values of Empress and Zenostar decreased with the use of Nupro fine paste (P<.05). Zenostar showed the lowest translucency (P<.05). The effect of prophylactic polishing pastes on gloss was minimal (P>.05). The gloss of Empress was higher than that of Zenostar and e.max (P<.05). The Pearson correlation showed that gloss and surface roughness were correlated (P<.001). CONCLUSIONS: Polishing procedures can alter the surface of a ceramic restoration.


Assuntos
Polimento Dentário , Porcelana Dentária , Cerâmica , Resinas Compostas , Desenho Assistido por Computador , Teste de Materiais , Propriedades de Superfície
7.
J Prosthet Dent ; 124(1): 75-80, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31732093

RESUMO

STATEMENT OF PROBLEM: The marginal gap and ceramic bond strength of metal-ceramic restorations are important for success. However, studies evaluating the marginal gap and ceramic bond strength of fixed partial dentures (FPDs) produced with 3D printing technologies such as selective laser melting (SLM) are scarce. PURPOSE: The purpose of this in vitro study was to investigate the marginal gap of cobalt-chromium (Co-Cr) alloy frameworks produced by SLM technology before and after ceramic firing. Additionally, the metal-ceramic bond strength was evaluated with the Schwickerath crack-initiation test according to the International Standards Organization (ISO) 9693-1:2012. MATERIAL AND METHODS: Conventional impressions were made, and the definitive cast of a patient requiring a 4-unit FPD was scanned. After designing the FPD, the files were sent to a service center for the fabrication of a metal master model, 80 Co-Cr frameworks, and 80 flat specimens (25×3×0.5 mm) with SLM technology. The marginal gap between frameworks and the abutment tooth of the metal master model was nondestructively measured by using an optical coordinate-measuring machine. A total of 80 sets, consisting of 1 framework and 1 flat specimen, were sent to 80 dental laboratory technicians for ceramic firing. Detailed instructions for correct manipulation of the framework and flat specimen were provided. The marginal gap was remeasured, and the 3-point bend test was used to evaluate metal-ceramic bond strength. RESULTS: Only 28 of the 80 dental technicians returned the specimens within a prespecified time and/or in adequate condition. The mean ±standard deviation marginal gap of the framework before ceramic firing was 25 ±9 µm and 34 ±12 µm after firing. The difference was statistically significant (P=.001). The mean ±standard deviation 3-point bend strength was 33 ±9 MPa. CONCLUSIONS: Ceramic firing affected the marginal gap; however, all Co-Cr frameworks had a marginal gap lower than 120 µm, which is reported to be a clinically acceptable limit. Most of the specimens (80%) had a metal-ceramic bond strength value higher than the 25-MPa ISO 9693 requirement. Five of 28 dental laboratory technicians were not able to comply with ceramic firing instructions.


Assuntos
Cobalto , Técnica de Fundição Odontológica , Cerâmica , Cromo , Ligas de Cromo , Porcelana Dentária , Humanos , Teste de Materiais , Ligas Metalo-Cerâmicas , Impressão Tridimensional , Propriedades de Superfície
8.
Odontology ; 107(4): 482-490, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30840218

RESUMO

The use of thin lithium disilicate (LD) occlusal veneers is an effective method to increase the vertical dimension of occlusion in cases of tooth wear. However, doubt remains regarding the threshold thickness to be used in this restoration class. This study aims to evaluate the effect of ceramic thickness on the survival rate and failure pattern of LD molar veneer restorations using a simplified fatigue testing machine. Sixty sound, freshly extracted human molars were used. Three groups (n = 20) were randomly created with different ceramic thicknesses (0.5, 0.8, and 1.2 mm), and 60 LD IPS e.max Press LT occlusal veneers were fabricated. The ceramic restorations were luted with a resin cement. The stainless-steel rotating drum of the ball mill contained 10 zirconia (Y-TZP) and 10 stainless steel spheres, in 500 mL of distilled water at 37 ± 1 °C. Crack growth in the LD restorations was evaluated under a stereomicroscope following each fatigue testing run (12 60-min runs). Progressive damage was observed as a function of cycling time. Survival was significantly influenced by the restoration thickness (p = 0.002, log-rank test), with thicker restorations exhibiting a higher survival rate. Thinner restorations (0.5 mm) showed significantly lower survival rate than 0.8- and 1.2-mm restorations (p < 0.016); no significant difference was observed between the 0.8- and 1.2-mm restorations. A threshold value of 0.8 mm may represent an acceptable compromise between fatigue resistance and tooth reduction.


Assuntos
Porcelana Dentária , Falha de Restauração Dentária , Cerâmica , Análise do Estresse Dentário , Humanos , Teste de Materiais , Projetos Piloto
9.
J Prosthet Dent ; 121(2): 292-297, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30093126

RESUMO

STATEMENT OF PROBLEM: Studies that evaluate the survival rate and load to fracture of premolars restored with inlays produced using different methods are lacking. PURPOSE: The 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 METHODS: Thirty 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). RESULTS: No 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. CONCLUSIONS: Premolars restored with inlays fabricated using the tested methods had similar survival rates and loads to fracture.


Assuntos
Resinas Compostas/química , Desenho Assistido por Computador , Falha de Restauração Dentária , Restaurações Intracoronárias , Dente Pré-Molar , Técnica de Moldagem Odontológica , Porcelana Dentária/química , Análise do Estresse Dentário , Humanos , Técnicas In Vitro , Teste de Materiais
10.
J Prosthodont ; 28(5): 536-540, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30357992

RESUMO

The aim of this report is to describe two standardized protocols for digital impression when implant support rehabilitation is used in the esthetic area. The two techniques were used to transfer all provisional crown parameters to definitive restorations in different clinical scenarios. In the direct technique, an impression (STL1) is made of the provisional restorations attached to the implants, with surrounding gingival tissue. The second scan (STL2) captures the sulcular aspect of the peri-implant soft tissue immediately after removal of the provisional restoration. The last impression (STL3) of the complete arch is made with a standardized scanbody attached to the implant to capture the 3D location of the implant. The direct technique is indicated when the peri-implant soft tissues are stable upon removal of the provisional restoration. The indirect technique is used when the gingival tissue collapses rapidly after the removal of the provisional crown. The impressions of the provisional restoration and the position of the implant are similar to those obtained with the direct technique, and the shape of the peri-implant tissue is extrapolated from the negative shape obtained from making the digital impression when the provisional restoration is taken out of the mouth. Finally, in both techniques the 3 scans are superimposed to obtain a file, which contains the details of the peri-implant soft tissue. The direct and indirect digital techniques allowed realization of a predictable definitive restoration in the esthetic zone in different clinical scenarios, reducing the duration of clinical procedures.


Assuntos
Coroas , Técnica de Moldagem Odontológica , Prótese Dentária Fixada por Implante , Restauração Dentária Temporária , Estética , Estética Dentária , Gengiva
11.
J Prosthodont ; 28(5): 556-563, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31038248

RESUMO

PURPOSE: To determine the trueness and precision of frameworks manufactured with a selective laser melting/milling hybrid technique (SLM/m) and conventional milling by comparing the implant-platform/framework interface with those of the original computer-aided design (CAD). MATERIALS AND METHODS: Using a virtual 6-implant-supported full-arch framework CAD drawing, 27 titanium replicas were manufactured by 3 independent manufacturing centers (n = 9/center) using a hybrid SLM/m technology (labs 1 and 2) or the conventional milling technique (lab 3). Using an opto-mechanical coordinate measuring machine, the frameworks' misfit distribution and patterns were analyzed, and the position error between paired platform positions within each framework was evaluated to calculate the misfit tendency for each group. A multilevel analysis using a mixed-effects model was conducted (α = 0.05). The trueness was evaluated as the dimensional difference from the original, while the precision as the dimensional difference from a repeated scan. RESULTS: The 3 dimensional misfits differed significantly among the 3 groups, with the milled group exhibiting the least accurate outcome (p = 0.005). The mean 3D positioning errors ranged from 8 to 16 µm and from 9 to 22 µm for the SLM/m technique (labs 1 and 2, respectively), and from 20 to 35 µm for conventional milling (lab 3). Regarding the misfit distribution pattern, the misfit increased with the distance between paired platform positions in all groups. CONCLUSIONS: All groups had 3D misfits well within the error limits reported in the literature. The 3D misfits of new hybrid (SLM/milling) and conventional (milling) procedures differed significantly among them, with the milling technique the less accurate and precise. The largest errors in all groups were found between the most distant implants, resulting in a correlation between the framework span and the inaccuracies.


Assuntos
Implantes Dentários , Prótese Dentária Fixada por Implante , Parafusos Ósseos , Desenho Assistido por Computador , Planejamento de Prótese Dentária , Titânio
12.
Periodontol 2000 ; 77(1): 84-92, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29493814

RESUMO

Crown lengthening is one of the most common surgical procedures in periodontal practice. Its indications include subgingival caries, crown or root fractures, altered passive eruption, cervical root resorption and short clinical abutment, and its aim is to re-establish the biologic width in a more apical position. While the procedure in posterior areas of the dentition has been thoroughly investigated, crown lengthening performed for esthetic reasons in the anterior areas is still a matter of debate and an evidence-based technique is not available. This paper provides accurate descriptions of the surgical and restorative phases of the esthetic crown-lengthening procedure by answering the following questions: what is the ideal surgical flap design? how much supporting bone should be removed? how should the position of the flap margin relate to the alveolar bone at surgical closure? and how should the healing phase be managed in relation to the timing and the position of the provisional restoration with respect to the gingival margin?


Assuntos
Aumento da Coroa Clínica/métodos , Estética Dentária , Alveolectomia/métodos , Alveoloplastia/métodos , Restauração Dentária Temporária , Humanos , Retalhos Cirúrgicos , Cicatrização/fisiologia
13.
J Prosthet Dent ; 120(2): 269-275, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29475752

RESUMO

STATEMENT OF PROBLEM: Although several monolithic zirconia ceramics have recently been introduced, the need for improved optical properties remains. The newest cubic-zirconia has been claimed to have optimal translucency characteristics for esthetic restorations. PURPOSE: This in vitro study evaluated the optical properties of novel cubic ultratranslucent (UT) and supertranslucent (ST) zirconia by comparing them with lithium disilicate (L-DIS) glass-ceramic for the manufacture of monolithic computer-aided design and computer-aided manufacturing (CAD-CAM) molar crowns. MATERIAL AND METHODS: The UT and ST multilayered zirconia and the low-translucency grade L-DIS were milled. Eighty monolithic crowns were made from 2 CAD files, corresponding to thicknesses of 1.0 and 1.5 mm, and subdivided (n=20) into 4 groups: UT1.0, UT1.5, ST1.0, and L-DIS1.5. All groups were shaded using A2 color standard. Translucency of the crowns was measured by total transmission, using a photoradiometer in a dark chamber; furthermore, the contrast ratio was analyzed using a dental spectrophotometer applied to the buccal surface of the crowns. Data were analyzed using the Kruskal-Wallis and post hoc multiple Mann-Whitney U tests with Bonferroni correction (α=.05 divided by the number of tests performed in each set). RESULTS: When the ceramic types were analyzed, using total transmission and contrast methods, they showed significantly different translucency levels: UT1.0>ST1.0>UT1.5>L-DIS1.5 (total transmission P<.001). Contrast ratio evaluation yielded similar results (P≤.006); however, the differences between ST1.0 and UT1.5 were not significant. CONCLUSIONS: Both the ST1.0 and UT1.0 crowns, even at the maximum thickness tested (UT1.5), showed significantly higher translucency than L-DIS. Zirconia translucency was improved by eliminating the tetragonal phase, which is responsible for the toughening effect; thus, further studies are advocated to investigate the mechanical resistance of cubic zirconia.


Assuntos
Coroas , Porcelana Dentária/química , Planejamento de Prótese Dentária , Zircônio/química , Cerâmica , Cor , Desenho Assistido por Computador , Materiais Dentários/química , Humanos , Luz , Teste de Materiais , Fenômenos Ópticos , Espectrofotometria , Propriedades de Superfície
14.
Clin Oral Implants Res ; 27(12): 1511-1514, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25907030

RESUMO

OBJECTIVE: This short communication reports on a novel digital technique designated - the "Fully Digital Technique (FDT)" - to take the impression of the peri-implant soft tissue and emergence profile with an intraoral scanner, digitally capturing both the three dimensional position of the implant platform and the coronal and gingival parts of the provisional retained restoration. MATERIALS AND METHODS: A first intraoral digital impression, which generated a standard triangulation language file (STL1), was taken using a standardized implant scanbody to detect the position of the implant. A second digital impression (STL2) with the provisional retained restoration in situ was performed in two steps: the first part of the scan captured all details of the vestibular and palatal sides of the provisional retained restoration and the adjacent teeth. The provisional retained restoration was then unscrewed, and the subgingival part of the restoration was scanned directly out of the mouth to determine its subgingival shape. STL1 and STL2 were imported into imaging software and superimposed using the "best fit" algorithm to achieve a new merged file (STL3) with the 3D implant position, the peri-implant mucosa, and emergence profile. The merged file was used to design the CAD/CAM customized abutment and to realize a stereolithographic model by 3D printing. RESULTS: The STL superimposition of digital impressions of the implant position and the provisional retained restoration constitute a novel technique to obtain a single STL file with the implant position and its peri-implant mucosal architecture. CONCLUSIONS: FDT is a rapid digital approach for achieving all information of the peri-implant soft tissue and emergence profile directly from the provisional retained restoration.


Assuntos
Desenho Assistido por Computador , Implantes Dentários para Um Único Dente , Técnica de Moldagem Odontológica , Estética Dentária , Humanos , Impressão Tridimensional
15.
J Adhes Dent ; 18(2): 143-9, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27042706

RESUMO

PURPOSE: To evaluate the fracture strength and the failure mode of endodontically treated teeth restored with composite resin overlays with and without glass-fiber reinforcement. MATERIALS AND METHODS: A total of 32 extracted molars were divided into four equal groups. In the NFR-NFRC (no foundation restoration, no fiber-reinforced composite) and NFR-FRC (no foundation restoration, fiber-reinforced composite) groups, only a 5-mm-thick composite resin layer sealed the pulp chamber floors, whereas in the FR-NFRC (foundation restoration, no fiber-reinforced composite) and FR-FRC (foundation restoration, fiber-reinforced composite) groups, a 3.0-mm foundation restoration was used. NFR-NFRC and FR-NFRC groups were restored with composite resin overlays, whereas NFR-FRC and FR-FRC groups were restored with fiber-reinforced composite resin overlays. All specimens were subjected to mechanical loading in a computer-controlled masticator and then the fracture resistance was evaluated. Differences in means were compared using two-way ANOVA and Tukey's test. The level of significance was set at ɑ = 0.05. RESULTS: All specimens successfully completed the fatigue test. The least fracture-resistant group was NFR-FRC, exceeded by FR-NFRC, NFR-NFRC, and FR-FRC, in that order, with FR-FRC being the most fracture-resistant group. Statistically significant differences were detected between the pairs NFR-NFRC/FR-FRC (p = 0.001), NFR-FRC/FR-FRC (p = 0.001), and FR-NFRC/FR-FRC (p = 0.001). Eight vertical root fractures occurred in group FR-NFRC, six in group NFR-NFRC, four in group NFR-FRC, and none occurred in group FR-FRC. CONCLUSIONS: Within the limitations of this in vitro study, the incorporation of glass fibers and the presence of a foundation restoration were found to increase the fracture resistance and can favorably influence the fracture mode.


Assuntos
Resinas Compostas/química , Materiais Dentários/química , Vidro/química , Restaurações Intracoronárias , Fraturas dos Dentes/fisiopatologia , Dente não Vital/terapia , Condicionamento Ácido do Dente/métodos , Idoso , Óxido de Alumínio/química , Fenômenos Biomecânicos , Força de Mordida , Corrosão Dentária/métodos , Cavidade Pulpar/ultraestrutura , Análise do Estresse Dentário/instrumentação , Humanos , Teste de Materiais , Metacrilatos/química , Pessoa de Meia-Idade , Poliuretanos/química , Distribuição Aleatória , Preparo de Canal Radicular/métodos , Silanos/química , Estresse Mecânico , Fatores de Tempo , Preparo do Dente/métodos , Raiz Dentária/lesões , Água/química
17.
Eur J Prosthodont Restor Dent ; 24(3): 130-137, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28509504

RESUMO

This study evaluated marginal adaptation before and after thermomechanical (TCML) loading, gap width and fracture strength of all-ceramic single crowns, as compared to porcelain-fused-to-metal (PFM). Thirty extracted premolars were prepared with a round shoulder of 1.0 mm depth. Specimens were restored with zirconia-ceramic (Group 1), lithium disilicate (Group 2) and metal-ceramic single crowns (Group 3). The replica of each sample was observed with a scanning electron microscope (SEM) to evaluate the crown-cement (c-c) and tooth-cement interface (t-c). After TCML, perfect margins decreased to 91.3% (c-c) and 93.9% (t-c) in Group 1, 94.6% (c-c) and 96.0% (t-c) in Group 2 and 73.5% (c-c) and 53.1% (t-c) in Group 3. The mean fracture strengths were 654.8 ± 98.1 N for Group 1, 551.3 ± 127 N for Group 2 and 501.43 ± 110.1 N for Group 3. All-ceramic systems could substitute for metal-ceramic crowns, but chipping of veneering ceramics, especially in zirconia-based crowns, should be investigated.


Assuntos
Coroas , Porcelana Dentária , Restauração Dentária Permanente , Ligas Metalo-Cerâmicas , Humanos , Técnicas In Vitro , Teste de Materiais
18.
J Adhes Dent ; 17(6): 567-74, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26734682

RESUMO

PURPOSE: To evaluate the marginal adaptation and fracture load of composite resin onlays reinforced with different substructures. MATERIALS AND METHODS: Thirty-two extracted, caries-free premolars were selected for this study and endodontically treated. Group 1 was used as the control group, and the teeth were restored only with as-manufactured composite resin overlays. Group 2 teeth were restored with composite resin overlays with 3 fiber-reinforced composite (FRC) layers placed horizontally on the bottom of the restoration. Group 3 teeth were restored with composite resin overlays with 6 fiber-reinforced composite (FRC) layers placed as in group 2. Group 4 teeth were restored with composite resin overlays and FRC placed with an anatomical design. All specimens underwent SEM evaluation of their marginal adaptation before and after thermocycling and cyclic mechanical loading. All specimens were then subjected to a fracture test, recording the value for the initial (IF) and final (FF) failure. Differences in the means were compared using matched-pairs t-tests and one-way ANOVA. The level of significance was set at α = 0.05. RESULTS: No statistically significant difference between the four groups in terms of marginal adaptation was observed at the tooth/luting composite and luting composite/overlay interfaces before and after loading. The fracture loads of IF and FF, from most to least resistant were: group 4 (1431.8 ± 294.3 N/1710.1 ± 326.6 N), group 3 (1428.1 ± 251.4 N/1467.9 ± 242.4 N), group 2 (852.6 ± 413.5 N/1058.1 ± 251.5 N) and group 1 (899.8 ± 352.7 N/923.5 ± 318.8 N). Significant differences (p = 0.026) were observed comparing group 1 to groups 2 and 3, and group 1 to 4. Three irreparable fractures were found in group 3, four in group 2, and five in groups 1 and 4. CONCLUSIONS: The presence or absence of reinforcement and the different configuration of the reinforcement fibers affect fracture strength but only partially the failure modality. The presence or absence of reinforcement does not alter marginal adaptation.


Assuntos
Dente Pré-Molar/patologia , Resinas Compostas/química , Adaptação Marginal Dentária , Materiais Dentários/química , Falha de Restauração Dentária , Vidro/química , Restaurações Intracoronárias , Dente não Vital/terapia , Condicionamento Ácido do Dente/métodos , Adulto , Idoso , Colagem Dentária , Planejamento de Prótese Dentária , Análise do Estresse Dentário/instrumentação , Humanos , Teste de Materiais , Microscopia Eletrônica de Varredura , Pessoa de Meia-Idade , Distribuição Aleatória , Cimentos de Resina/química , Silanos/química , Estresse Mecânico , Propriedades de Superfície , Temperatura
19.
J Dent ; 150: 105350, 2024 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-39321738

RESUMO

OBJECTIVE: To assess the clinical performance of monolithic screw-retained implant-supported zirconia crowns (MSI) bonded or mechanically retained on prefabricated Ti-bases using a complete digital workflow. METHODS: A retrospective analysis was conducted on patients who underwent single dental implant procedures between January 2017 and May 2018. Inclusion criteria were: patients over 18 years of age; implants placed in posterior sites; MSI on prefabricated Ti-base realized by using a complete digital workflow; a minimum follow-up period of 2 years. Cemented crowns and fixed dental prosthesis were excluded. Mechanical complications included: fracture of Ti-base; loss of retention; loosening of Ti-base screws. Technical complications included: fracture and debonding of monolithic zirconia. Biological complication was set strictly at a probing pocket depth of 5 mm and bleeding on probing or pus secretion. RESULTS: A total of 144 dental implants placed in 127 patients were included, 73 with a fully tapered implant system (BLX) and 71 with a conical connection system (Nobel Parallel CC). Of the 73 BLX implants, 4 experienced loosening of the Ti-base screw, while 3 Nobel Parallel CC implants experienced the same problem. In addition, 4 fractures of the Ti-base and 6 fractures of the inner surface of the monolithic zirconia were observed in the Nobel Parallel CC implants. Cumulative survival was 100 % for bonded crowns and 85 % for mechanically retained crowns. Radiographic evaluation revealed a mean CBL of 0.12 mm for the BLX and 0.13 mm for the Nobel Parallel CC implants with no statistically significant differences between the Ti-base types. There was no evidence of bleeding on probing or pus secretion. All probing pocket depths were <3 mm. CONCLUSION: The use of a prefabricated Ti-base remains a clinically acceptable choice, however, MSIs bonded to prefabricated Ti-bases had fewer mechanical and technical complications than the MSI mechanically retained to a prefabricated Ti-base.

20.
Dent J (Basel) ; 12(7)2024 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-39057005

RESUMO

Objective: To determine the effect of grit-blasting before and after sintering on the surface roughness of zirconia and the micro-tensile bond strength of a pressable veneering ceramic to zirconia. Methods: Pre-sintered zirconia blocks (IPS e.max ZirCAD, Ivoclar) were divided into four test groups of three specimens each and a control group ('CTR'; no surface treatment). Pre-S-30, Pre-S-50, and Pre-S-110 were grit-blasted with 30-µm SiO2-coated Al2O3, 50-µm Al2O3 and 110-µm Al2O3 particles, respectively, before sintering. Post-S-30 was grit-blasted with 30-µm SiO2-coated Al2O3 after sintering. For each treatment, the surface roughness was measured (Ra, Perthometer M4P, Mahr Perthen). After sintering the zirconia blocks, a liner was applied and a pressable ceramic (IPS e.max ZirPress, Ivoclar) was heat-pressed. Sixteen microbars were obtained from each block and submitted to micro-tensile bond-strength (µTBS) testing. Data were analyzed with one-way ANOVA. Any correlation between Ra and µTBS was evaluated (Sperman test). Results: Grit-blasting before sintering with 110-µm Al2O3 (RaPre-S-110 = 3.4 ± 0.4 µm), 50-µm Al2O3 (RaPre-S-50 = 2.3 ± 0.5 µm), and 30-µm SiO2-coated Al2O3 (RaPre-S-30 = 1.2 ± 0.2 µm) resulted in significantly higher roughness than grit-blasting after sintering with 30-µm SiO2-coated Al2O3 (RaPost-S-30 = 0.5 ± 0.1 µm). The highest µTBS was measured when the sintered zirconia was grit-blasted with 30-µm SiO2-coated Al2O3 (µTBSPost-S-30 = 28.5 ± 12.6 MPa), which was significantly different from that of specimens that were grit-blasted before sintering (µTBSPre-S-30 = 21.8 ± 10.4; µTBSPre-S-50 = 24.1 ± 12.6; µTBSPre-S-110 = 26.4 ± 14.1) or were not grit-blasted (µTBSCTR = 20.2 ± 11.2). Conclusions: Grit-blasting zirconia before sintering enhanced the surface roughness proportionally to the particle size of the sand used. Grit-blasting with 30-µm SiO2-coated Al2O3 after sintering improved bonding of the veneering ceramic to zirconia. Clinical Significance: As grit-blasting with 30-µm SiO2-coated Al2O3 after sintering improved bonding of the veneering ceramic to zirconia, it may reduce veneering ceramic fractures/chipping.

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