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Fracture characteristics and translucency of multilayer monolithic zirconia crowns of various thicknesses.
Kang, Chien-Ming; Hsu, Wen-Chieh; Chen, May-Show; Wu, Hsuan-Yu; Mine, Yuichi; Peng, Tzu-Yu.
Afiliación
  • Kang CM; Huayi Dental Laboratory, Taipei, Taiwan; School of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei, Taiwan.
  • Hsu WC; School of Dentistry, College of Oral Medicine, Chung Shan Medical University, Taichung, Taiwan; Department of Oral Hygiene, Hsin Sheng Junior College of Medical Care and Management, Taoyuan, Taiwan; Research Center of Precision Biomedical Implants, College of Oral Medicine, Taipei Medical University
  • Chen MS; School of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei, Taiwan; Division of Prosthodontics, Department of Dentistry, Taipei Medical University Hospital, Taipei, Taiwan.
  • Wu HY; School of Dental Technology, College of Oral Medicine, Taipei Medical University, Taipei, Taiwan.
  • Mine Y; Department of Medical Systems Engineering, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan; Project Research Center for Integrating Digital Dentistry, Hiroshima University, Hiroshima, Japan.
  • Peng TY; School of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei, Taiwan. Electronic address: typeng@tmu.edu.tw.
J Dent ; 145: 105023, 2024 06.
Article en En | MEDLINE | ID: mdl-38670331
ABSTRACT

OBJECTIVES:

Multilayer monolithic zirconia (M-Zr) crowns can be engineered to achieve gradational translucency and color intensity. However, this modification may compromise the mechanical strength, raising concerns regarding the ability of M-Zr crowns to withstand occlusal stresses. The effects of M-Zr crown thickness on translucency and ability to endure occlusal forces were investigated at different tooth positions (incisors, premolars, and molars). The objective was to determine the minimal thickness of M-Zr crowns used in tooth preparation to meet aesthetic and functional demands.

METHODS:

M-Zr samples (Vita A1) with four thicknesses (0.5, 1.0, 1.5, and 2.0 mm) were prepared and subjected to translucency testing using a digital colorimeter by 3-third and 9-square division methods. Crown-shaped M-Zr samples with three thicknesses (1.0, 1.5, and 2.0 mm) and three tooth positions (incisor, premolar, and molar) were digitally designed, and 2.0 mm metal abutments were fabricated. The samples were bonded to the abutments; their fracture characteristics were evaluated using a universal testing machine, and their fracture surfaces examined using an optical microscope. Statistical analyses included the Shapiro-Wilk test, Pearson correlation, and one-way and two-way ANOVA with a post hoc Tukey HSD test (α = 0.05).

RESULTS:

Color analysis results revealed a significant negative correlation between thickness and translucency (r < -0.96, P < 0.01), with the highest values in the incisal region. Cross-sectional profiles confirmed the uniform thickness and morphology of the digitally designed M-Zr crowns. The results of fracture strength analysis showed position-dependent variability, a strong positive correlation with thickness (r > 0.96, P < 0.01), and fracture strengths consistently exceeding 1200 N across all tooth positions. Fracture patterns indicated that thinner crowns at the incisors and molars were more prone to cracking, whereas those at the premolars demonstrated significantly higher strength (4872.51 N, P < 0.05), only with crack or even no fracture occurring at 2.0 mm.

CONCLUSIONS:

Thickness significantly influenced both the translucency and fracture strength of M-Zr, with the tooth position playing an additional role, albeit to a lesser extent. Although thinner crowns exhibited lower strength at each tooth position, even at a thickness of 1.0 mm, fracture strength exceeding 1200 N was maintained, surpassing the typical occlusal forces. Thus, it can be asserted that M-Zr crowns with a minimum thickness of 1.0 mm can meet both aesthetic and functional requirements.
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Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Circonio / Diente Premolar / Ensayo de Materiales / Diseño de Prótesis Dental / Coronas / Materiales Dentales Límite: Humans Idioma: En Revista: J Dent Año: 2024 Tipo del documento: Article País de afiliación: Taiwán Pais de publicación: Reino Unido

Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Circonio / Diente Premolar / Ensayo de Materiales / Diseño de Prótesis Dental / Coronas / Materiales Dentales Límite: Humans Idioma: En Revista: J Dent Año: 2024 Tipo del documento: Article País de afiliación: Taiwán Pais de publicación: Reino Unido