Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2023 Dec 22;34(5):79-86.
doi: 10.1590/0103-6440202305496. eCollection 2023.

Long-term effect of firing protocols on surface roughness and flexural strength of lithium disilicate glass-ceramic

Kaíssa da Cunha Lima  1 , Rocio Geng Vivanco  1 , Pedro Roberto Braz Rodrigues  1 , Ana Lúcia Pereira Caetano  1 , Fernanda de Carvalho Panzeri Pires-de-Souza  1
Affiliations

Long-term effect of firing protocols on surface roughness and flexural strength of lithium disilicate glass-ceramic

Kaíssa da Cunha Lima et al. Braz Dent J. .

Abstract
in English, Portuguese

This study evaluated the effect of different firing protocols on the surface roughness and flexural strength of CAD/CAM lithium disilicate glass-ceramic (LD) after aging methods. Forty-two LD bars of 16 x 4 x 2 mm (IPS e-max CAD, Ivoclar) were randomly separated into two groups according to firing protocols: Single firing-Staining, glazing, and crystallization in a single step; Multiple firings-Crystallization+First staining+Firing+Second staining+Firing+Glazing+Firing. After protocols, initial surface roughness readings were taken (Surfcorder SE1700, Kosakalab). Samples were then randomly separated into three groups (n=7) according to the aging methods they were submitted: Thermomechanical cycling (TMC, ER System, Erios, 1,200,000 cycles, 0.3 MPa, 2 Hz and 5°C/37°C/55°C, 30 s swell time); Simulated toothbrushing (STB, Pepsodent, MAVTEC, 73,000 cycles), and Control (no aging). Final surface roughness readings were done, and samples were submitted to a three-point bending test (OM100, Odeme Dental Research) and fractographic analysis by scanning electron microscopy (EVO-MA10, ZEISS). Data were analyzed (2-way ANOVA, (α=.05). There was no difference (p>.05) in the flexural strength between the firing protocols, regardless of the aging method. STB decreased the flexural strength of samples submitted to multiple firings, different from control (p<.05). Without aging (Control), before TMC, and after STB, LD had lower surface roughness when submitted to multiple firings than to single firing (p<.05). The firing protocols did not affect the flexural strength or the surface roughness of the lithium disilicate glass-ceramic, even after aging. However, toothbrushing negatively affected the flexural strength and smoothed the surface of the ceramic submitted to multiple firings.

Este estudo avaliou o efeito de diferentes protocolos de queima na rugosidade de superfície e resistência à flexão de uma cerâmica vítrea de dissilicato de lítio (DL) para CAD/CAM, após métodos de envelhecimento. Quarenta e dois barras de DL (IPS e-max CAD, Ivoclar) de 16 x 4 x 2 mm foram separadas aleatoriamente em dois grupos de acordo com os protocolos de queima: Single firing-Pigmentação, glazeamento e cristalização em única etapa. Multiple firings-Cristalização+Primeira camada do pigmento+Queima+Segunda camada do pigmento+Queima+Glazeamento+Queima. Após os protocolos, foram realizadas leituras iniciais de rugosidade de superfície (Surfcorder SE1700, Kosakalab). As amostras foram então separadas aleatoriamente em três grupos (n=7) segundo o método de envelhecimento a que foram submetidas: Ciclagem termomecânica (CTM, Sistema ER, Erios, 1.200.000 ciclos, 0.3 MPa, 2 Hz e 5°C/37°C/55°C, 30 s de imersão), Escovação simulada (ES, Pepsodent, MAVTEC, 73.000 ciclos) e Controle (sem envelhecimento). Leituras finais de rugosidade foram realizadas, e as amostras foram submetidas ao ensaio de resistência à flexão em três pontos (OM100, Odeme Dental Research) e à análise fractográfica por microscopia eletrônica de varredura (EVO-MA10, ZEISS). Os dados foram analisados (ANOVA de dois fatores, (α=.05). Não houve diferença (p>.05) na resistência à flexão entre os protocolos de queima, independente do envelhecimento. ES diminuiu a resistência à flexão das amostras submetidas a multiple firings, diferente do controle (p<.05). Sem envelhecimento (Controle), antes da CTM e após ES, LD apresentou menor rugosidade de superfície quando submetido a multiple firings do que a single firing (p<.05). Os protocolos de queima não afetaram a resistência à flexão nem a rugosidade de superfície da cerâmica vítrea de dissilicato de lítio, mesmo após envelhecimento. No entanto, a escovação afetou negativamente a resistência à flexão e poliu a superfície da cerâmica submetida a multiple firings.

PubMed Disclaimer

Figures

Figure 1
Figure 1. The flowchart presents all the steps of the study.
Figure 2
Figure 2. Representative photomicrographs (SEM) of the samples submitted to different firing protocols and aging methods (500× and 2 000×). Narrow = Bubble; Hashtag symbol = Radial crack; Finger point = Chipping; Line = Cracks; Circle = Particles from the toothpaste.
See this image and copyright information in PMC

References

    1. Aziz A, El-Mowafy O, Tenenbaum HC, Lawrence HP, Shokati B. Clinical performance of chairside monolithic lithium disilicate glass-ceramic CAD-CAM crowns. J Esthet Restor Dent. 2019;31:613–619. doi: 10.1111/jerd.12531. - DOI - PubMed
    1. Meng H, Xie H, Yang L, Chen B, Chen Y, Zhang H, et al. Effects of multiple firings on mechanical properties and resin bonding of lithium disilicate glass-ceramic. J Mech Behav Biomed Mater. 2018;88:362–369. - PubMed
    1. Gozneli R, Kazazoglu E, Ozkan Y. Flexural properties of leucite and lithium disilicate ceramic materials after repeated firings. J Dent Sci. 2014;9:144–150.
    1. Tamsu Selli N, Basaran N. Controlling the hardness and wear resistance of opaque white glaze by addition of halloysite clay in the composition. Bol la Soc Esp Ceram y Vidr. 2022;1:14–14.
    1. Wang F, Gao J, Wang H, Chen J. Flexural strength and translucent characteristics of lithium disilicate glass-ceramics with different P2O5 content. Mater Des. 2010;31:3270–3274.