• Journal of the korean academy of Pediatric Dentistry
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• v.46 no.2
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• pp.127-134
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• 2019

The aim of this study was to evaluate the compomer cement and resin cement as an orthodontic band cement on zirconia crown. A total of 30 specimens were prepared. Preformed stainless steel crowns and zirconia crowns of upper right second primary molar were used. Orthodontic bands were cemented on stainless steel crowns (Group I, n = 10) and zirconia crowns (Group II, n = 10) with compomer cement. The other bands were cemented on zirconia crowns with resin cement (Group III, n = 10). The tensile loads were applied to band to measure the bond strength. The mean of bond strengths of group I, II and III were 0.79 MPa, 1.09 MPa and 1.56 MPa respectively. Bond strength of group II is significantly higher than group I. There was no significant difference between group II and III. Compomer cement and resin cement containing functional monomers showed favorable bond strength of orthodontic bands.

• Journal of the korean academy of Pediatric Dentistry
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• v.50 no.3
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• pp.307-317
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• 2023

Due to increasing demand for aesthetics, zirconia crowns have become a popular choice for treating primary molars. However, there is limited literature available comparing the survival rates of zirconia crowns with those of other restorative materials. The objective of this study was to compare the 36-month survival rates of zirconia crowns and stainless steel crowns for proximal caries, as well as to analyze failure types associated with each crown type. Electronic medical records and radiographs of 1,061 primary molars from 498 patients treated with 2 types of prefabricated crowns at Chosun University Dental Hospital and 2 private dental clinics between 2017 and 2019 were collected and analyzed. The survival rate of zirconia crowns was found to be lower compared to that of stainless steel crowns. Regarding the groups without pulp treatment, the survival rate of stainless steel crowns was significantly higher than that of zirconia crowns. However, in the groups that received pulp therapy, no significant difference in the survival rates was observed between the two preformed crowns. Notably, abnormal root resorption or periapical lesions were identified as the primary cause of restorative failure in stainless steel crowns, whereas loss of restoration was the predominant cause in zirconia crowns. This study holds valuable implications for clinicians when selecting preformed crowns for primary molars.

• Journal of the korean academy of Pediatric Dentistry
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• v.45 no.3
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• pp.314-323
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• 2018

The aim of this study was to evaluate the shear bond strength of three luting cements and to identify the effect of thermocycling. Zirconia discs were made similar to the inner surface of a preformed pediatric zirconia crown ($NuSmile^{(R)}$ ZR crown: ZRCr). The similarity between the zirconia discs and the inner surface of a ZRCr was confirmed by scanning electron microscope. Three luting cements were $Ketac^{TM}$ Cem Permanent Glass Ionomer Luting Cement (KGI), $RelyX^{TM}$ Luting Plus Cement (RLP), $RelyX^{TM}$ Unicem Self-Adhesive Universal Resin Cement (RUR). Three luting cements were bonded according to the manufacturer's instructions for 60 zirconia discs and 60 dentin of primary teeth. Total of 120 specimens were divided into two subgroups: One was not aged, and the other was tested with 5500 thermocycling. Shear bond strength was measured using a universal testing machine, and the fracture patterns were observed with SEM. On the zirconia discs and the dentin of primary teeth, shear bond strength of RUR was higher than that of KGI and RLP, and there were statistically significant differences by cement type. The shear bond strength differences for RUR were not statistically significant depending on thermocycling.

• Journal of the korean academy of Pediatric Dentistry
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• v.46 no.3
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• pp.318-327
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• 2019

The purpose of this study was to identify which combination of zirconia crowns and cements is most similar in color to the maxillary primary incisors by varying the color of zirconia crowns, crown thickness, and shade of cements. Prefabricated zirconia crowns in 3 shades and crowns fabricated using 6 types of zirconia blocks were used in this study. These were filled with A2-shade or translucent-shade resin cement and the $L^*$, $a^*$, and $b^*$ values were calculated using a spectrophotometer. The color differences between the natural teeth and the zirconia crowns were assessed. The shade of the final restoration was more similar to that of the natural teeth using A2-shade than translucent-shade resin cement. Application of A2-shade cement to a 0.5-mm-thick crown fabricated from a smile series 2 zirconia block resulted in the color most similar to that of the natural teeth. A2-shade resin cement is recommended for zirconia crown restoration in anterior primary teeth compared to TR-shade resin cement for more esthetic restoration. Since restorations with Nu-smile zirconia crowns were not esthetically favorable in terms of shade, improvement of the shade characteristics of the product or development of a new kind of zirconia crown is required.