Browsing by Author "Supornpun, Noppamath"

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    Effects of shade and thickness on the translucency parameter of anatomic-contour zirconia, transmitted light intensity, and degree of conversion of the resin cement
    (Elsevier, 2023-01) Supornpun, Noppamath; Oster, Molly; Phasuk, Kamolphob; Chu, Tien-Min G.; Biomedical Sciences and Comprehensive Care, School of Dentistry
    Statement of problem Anatomic-contour zirconia prostheses are usually cemented with resin cement. However, information regarding the effects of the zirconia shade and thicknesses on the translucency of the prosthesis, the intensity of the transmitted light beneath the prosthesis, and the subsequent degree of conversion in the resin cement is sparse. Purpose The purpose of this in vitro study was to investigate the translucency parameter in 3 anatomic-contour zirconia specimens of 2 shades at 5 different thicknesses and to investigate the transmitted light intensity and degree of conversion of the resin cement beneath the ceramic specimens by using a traditional zirconia and a lithium disilicate glass ceramic as controls. Material and methods Ceramic specimens from 1 anatomic-contour zirconia in a generic shade (CAP FZ) and 2 anatomic-contour zirconias in A2 shade (Zirlux and Luxisse) were used. Lithium disilicate in HT A2 shade (IPS e.max CAD) and traditional zirconia in a generic shade (CAP QZ) were used as controls. A total of 125 ceramic specimens (n=25) were fabricated to a final specimen dimension of 12×12 mm and in thicknesses of 1.0, 1.25, 1.5, 1.75, and 2.0 mm according to the manufacturers’ recommendations. The CIELab color space for all specimens placed against a white and black ground was measured with a spectrophotometer (CM-2600D), and the translucency parameters were calculated for the materials at various thicknesses. A light-polymerizing unit (DEMI LED) was used to polymerize the resin cement (Variolink II) placed beneath the ceramic specimens. Transmitted light intensity from the polymerization unit beneath the ceramic specimens was measured by using a spectrophotometer (MARC Resin Calibrator), and the transmittance of each specimen was calculated. The coefficient of absorption of each material was calculated from the regression analysis between the natural log of transmittance and specimen thickness. The degree of conversion of resin cement was measured by using a Fourier transformation infrared (FTIR) spectrophotometer. The results were analyzed by using 2-way ANOVA (α=.05). The relationship between the transmittance and the translucency parameter was evaluated by plotting the transmittance against the translucency parameter value of each specimen. Results The translucency parameter decreased with increasing thickness in all 5 material groups. All anatomic-contour zirconia had lower translucency parameters than e-max CAD (P<.001). The same results were found for the intensity of the transmitted light (P<.001). Both A2 shade anatomic-contour zirconia (Zirlux and Luxisse) showed significantly lower light transmittance than a generic shade anatomic-contour zirconia (CAP FZ) (P<.001). The coefficients of absorption were found to range from 0.63 to 1.72 mm-1, and reflectance from 0.10 to 0.25. The results from the degree of conversion of resin cement after polymerization through 1 to 2 mm of specimens showed a significantly higher degree of conversion in the e.max group than in all other groups (P<.001). The correlation between translucency parameter and the intensity of the transmitted light suggested that the relationship was shade dependent. Conclusions The translucency parameter and the transmitted light intensity of ceramic material were influenced by the type of ceramic and the shade and thickness of the ceramic. The combined effects of layer thickness and the intensity of the transmitted light in the A2 shade anatomic-contour zirconia (Zirlux and Luxisse) resulted in a lower degree of conversion in resin cement than in a generic shade anatomic-contour zirconia (CAP FZ) at layer thicknesses of 1.75 and 2 mm.
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    Importance of Vertical Dimension in Facial Esthetics.
    (04/13/15) Supornpun, Noppamath; Levon, John; Supornpun, Noppamath; Levon, John; Aesthetic Dentistry
    The objective is to discuss the importance in the determination of the vertical dimension of occlusion in prosthodontic treatment. Case I: A 43-year-old Caucasian female presented with chief complaints of both poor function and esthetics. The medical history revealed a history of cirrhosis, Hepatitis B and depression. In 2011, she presented edentulous with some lower impacted teeth. Three sets of complete dentures were fabricated and delivered. These dentures caused her various problems including complaint of the thick and overextended borders, unacceptable esthetics and ear pain. Due to lack of posterior inter-occlusal space, vertical dimension was increased so much that the resulting dentures were unsatisfying esthetically and auricular discomfort. Case II: A 75-year-old Caucasian male presented with a chief complaints of a broken denture, joint discomfort and esthetic concern. The medical history revealed a history of angina pectoris, hypertension and depression. He continuously complained about his joint pain and broken prosthesis since 2011. Repairs were done several times but they did not eliminate his problem. In 2013, he was diagnosed with a loss of vertical dimension. When his vertical was reestablished at its proper position, his joint discomfort was resolved and his esthetics was greatly improved. Conclusion: Determination of the proper vertical dimension of occlusion is a crucial factor in the overall success of a restorative case. For correct diagnosis and treatment, the restorative dentist should use past dental history, facial profile, past photographs, provisional prosthesis and mounted diagnostic casts.
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    Translucency and degree of conversion of resin cement with different thickness of full contour zirconia
    (2015) Supornpun, Noppamath; Chu, Tien-Min Gabriel; Brown, David; Hovijitra, Suteera; Bottino, Marco C.; Levon, John A.
    Background: Traditionally, zirconia has been used as a core material for allceramic crowns that are later covered by a more esthetic veneering layer. Recently, new zirconia materials with higher translucency commonly referred to as the “full contour zirconia” have been introduced with the aim to allow dentist to fabricate entire allceramic crown from the material with acceptable esthetic and mechanical functions without the need for veneering. However, there is little information in the literature regarding the translucency of full contour zirconia and the degree of conversion of resin cement underneath the full contour zirconia. Objectives: 1) To investigate the translucency parameter (TP) of recently marketed full contour zirconia and compare that to traditional zirconia and lithium disilicate glass ceramic (LDGC) at different thicknesses. 2) To evaluate the degree of conversion (DC) of the resin cement through different thicknesses of the full contour zirconia, traditional zirconia and LDGC. Alternative hypothesis: The new generation zirconia at the clinically recommended thickness has lower translucency than that of LDGC and higher than that of non-veneered traditional zirconia. In addition, DC of resin cement under full contour zirconia is lower than that of LDGC and higher than that of traditional zirconia. Methods: 150 ceramic specimens (12 x12 mm with thickness of 1-2 mm for LDGC and Zirconia) were divided into 6 groups according to the type of material, as follow: LDGC (IPS e-max CAD), Traditional Zirconia (CAP QZ), full contour zirconia (CAP FZ, Zirlux, Bruxzir, KDZ Bruxer). The TP for materials at various thicknesses were measured by a spectrophotometer (CM-2600D). The DC of the light curing resin cement (Variolink II) underneath the ceramic disks was measured by FTIR. Result: All full contour zirconia has lower translucency parameter and light transmission than LDGC. The translucency parameter decreases with increasing thickness of any type of ceramic. There were no significant differences in the degree of conversion of resin cement among the type of ceramic disc, except Bruxzir. The correlation of TP between various thicknesses and the types of ceramic materials was established by a regression analysis.