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1.
Int J Comput Dent ; 23(3): 225-233, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32789310

RESUMEN

AIM: To evaluate the fracture resistance and failure pattern of 3D-printed and milled composite resin crowns as a function of different material thicknesses. MATERIALS AND METHODS: Three typodont tooth models were prepared to receive a full coverage composite resin crown with different thicknesses (0.5, 1.0, and 1.5 mm). The prepared master casts were digitally scanned using an intraoral scanner, and the STL files were used to fabricate 60 nanocomposite crowns divided into two groups according to the material thickness (n = 10) and fabrication method: a 3D-printed group (3D) using an SLA printer with nanocomposite, and a milled group (M) using a milling machine and composite blocks. All crowns were adhesively seated on stereolithography (SLA)-fabricated dies. All samples were subjected to thermomechanical loading and fracture testing. The load to fracture [N] was recorded and the failure pattern evaluated. Data were statistically analyzed using a two-way ANOVA followed by a Bonferroni post hoc test. The level of significance was set at α = 0.05. RESULTS: The 3D group showed the highest values for fracture resistance compared with the milled group within the three tested thicknesses (P < 0.001). The 3D and M groups presented significantly higher load to fracture for the 1.5-mm thickness (2383.5 ± 188.58 N and 1284.7 ± 77.62 N, respectively) compared with the 1.0-mm thickness (1945.9 ± 65.32 N and 932.1 ± 41.29 N, respectively) and the 0.5-mm thickness, which showed the lowest values in both groups (1345.0 ± 101.15 N and 519.3 ± 32.96 N, respectively). A higher incidence of irreparable fractures was observed for the 1.5-mm thickness. CONCLUSION: 3D-printed composite resin crowns showed high fracture resistance at different material thicknesses and can be suggested as a viable solution in conservative dentistry.


Asunto(s)
Porcelana Dental , Fracaso de la Restauración Dental , Cerámica , Diseño Asistido por Computadora , Coronas , Diseño de Prótesis Dental , Análisis del Estrés Dental , Humanos , Ensayo de Materiales , Impresión Tridimensional
2.
J Prosthodont ; 27(9): 860-867, 2018 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-30281183

RESUMEN

PURPOSE: The aim of this study was to compare the effect of Nd:YAG laser to that of a new varnish: MI Varnish with RECALDENT (GC), for the treatment of dentin hypersensitivity, with a follow-up of 6 months. Dentinal hypersensitivity was evaluated using a new thermal test never before used on dental tissue. MATERIALS AND METHODS: A split-mouth design was used where teeth on one side received the same type of treatment. Twelve patients suffering from dentin hypersensitivity were chosen. Fifty-four teeth were divided into 27 pairs. Twenty-seven teeth received the Nd:YAG laser treatment, and the 27 contralateral teeth received MI Varnish application. Five parameters were measured, and the measurements were taken before treatment at baseline (T0), after 1 week (T1), 1 month (T2), 3 months (T3), and 6 months (T4) of the application. Air stimulation to obtain the Schiff air score, the score of discomfort according to the visual analog scale (VAS), the tactile score, and the thermal test that determines the minimum cold-stimulating temperature and the maximum heat-stimulating temperature were all used to assess sensitivity. Statistical analyses of the data were performed, and the significance level was set at p ≤ 0.05. Exact Fisher tests and Chi-Square tests were conducted to compare percentages. RESULTS: There was a clear decrease in dentin hypersensitivity for both treatments (Nd:YAG laser and MI Varnish) especially between baseline and 1 week, with maintenance of this state through the 6-month follow-up period. The difference between the two treatments was not significant, comparing, over time, the Schiff air score, the thermal test, and the VAS; however, the tactile score was significantly improved 6 months after the application of MI Varnish compared to the laser (p = 0.05). CONCLUSION: There was no significant difference between the two treatments, Nd:YAG laser and MI Varnish. Both treatments were effective and reduced dentin hypersensitivity immediately after treatment up to 6 months.


Asunto(s)
Caseínas/uso terapéutico , Sensibilidad de la Dentina/terapia , Láseres de Estado Sólido/uso terapéutico , Adulto , Frío/efectos adversos , Sensibilidad de la Dentina/tratamiento farmacológico , Sensibilidad de la Dentina/cirugía , Calor/efectos adversos , Humanos , Persona de Mediana Edad , Adulto Joven
3.
Biomed Res Int ; 2016: 6507924, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27830151

RESUMEN

Objective. To investigate the shear bond strength of self-adhering flowable resin composite, to dentin, after exposing it to Er:YAG laser radiation, at different energy densities. Materials and Methods. Sixty freshly extracted human third molars were randomly divided into five groups (n = 12). In the control group, dentin was left unirradiated, whereas, in the other four groups, dentin was irradiated with Er:YAG laser in noncontact mode (MSP mode = 100 µs; 10 Hz; beam diameter: 1.3 mm; speed of 1 mm/second; air 6 mL/min; and water 4 mL/min), and respectively, with the following level of energy (50 mJ, 60 mJ, 80 mJ, and 100 mJ). Then, self-adhering flowable resin composite was bonded to all prepared dentin surfaces. Shear bond strength (SBS) was applied and fractured surfaces were examined using scanning electron microscopy. Results. SBS values showed significant differences in 60 mJ (P < 0.05) compared to other groups. Morphological evaluation revealed tags or plugs in dentinal tubules, especially when 60 mJ and 80 mJ were used. All four groups tended to leave more residues on the dentin surface, than the control group. Conclusion. Er:YAG dentin irradiation may enhance SBS of the self-adhering flowable resin composite when it is used at the appropriate low level of energy density.


Asunto(s)
Resinas Compuestas/química , Recubrimiento Dental Adhesivo/métodos , Cementos Dentales/química , Dentina/química , Láseres de Estado Sólido , Diente Molar/química , Grabado Ácido Dental , Aire , Humanos , Microscopía Electrónica de Rastreo , Distribución Aleatoria , Cementos de Resina/química , Robótica , Resistencia al Corte , Resistencia a la Tracción , Agua/química
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