Yi Yang-Jin
(Dept. of Prosthodontics, College of Dentistry, Kangnung National University, and Research Institute of Oral Science)
,
Yoon Dong-Jin
(NDE Lab., Korea Research Institute of Standards and Science)
,
Park Chan-Jin
(Dept. of Prosthodontics, College of Dentistry, Kangnung National University, and Research Institute of Oral Science)
,
Cho Lee-Ra
(Dept. of Prosthodontics, College of Dentistry, Kangnung National University, and Research Institute of Oral Science)
Statement of problem. In dentistry, the minimally prepared inlay resin-bonded fixed partial denture (FPD) made of new ceromer / fiber-reinforced composite (FRC) was recently introduced. However, the appropriate dimensions for the long-term success and subsequent failure strength are still unknown. P...
Statement of problem. In dentistry, the minimally prepared inlay resin-bonded fixed partial denture (FPD) made of new ceromer / fiber-reinforced composite (FRC) was recently introduced. However, the appropriate dimensions for the long-term success and subsequent failure strength are still unknown. Purpose. The aim of this study was to investigate the most fracture-resistible thickness combination of the ceromer / FRC using a universal testing machine and an AE analyzer. Material and Methods. A metal jig considering the dimensions of premolars and molars was milled and 56-epoxy resin dies, which had a similar elastic modulus to that of dentin, were duplicated. According to manufacturer's instructions, the FRC beams with various thicknesses (2 to 4 mm) were constructed and veneered with the 1 or 2 mm-thick ceromers. The fabricated FPDs were luted with resin cement on the resin dies and stored at room temperature for 72 hours. AE (acoustic emission) sensors were attached to both ends, the specimens were subjected to a compressive load until fracture at a crosshead speed of 0.5 mm/min. The AE and failure loads were recorded and analyzed statistically. Results. The results showed that the failure strength of the ceromer/FRC inlay FPDs was affected by the total thickness of the connectors rather than the ceromer to FRC ratio or the depth of the pulpal wall. Fracture was initiated from the interface and propagated into the ceromer layer regardless of the change in the ceromer / FRC ratio. Conclusion. Within the limitations of this study, the failure loads showed significant differences only in the case of different connector thicknesses, and no significant differences were found between the same connector thickness groups. The application of AE analysis method in a fiber-reinforced inlay FPD can be used to evaluate the fracture behavior and to analyze the precise fracture point.
Statement of problem. In dentistry, the minimally prepared inlay resin-bonded fixed partial denture (FPD) made of new ceromer / fiber-reinforced composite (FRC) was recently introduced. However, the appropriate dimensions for the long-term success and subsequent failure strength are still unknown. Purpose. The aim of this study was to investigate the most fracture-resistible thickness combination of the ceromer / FRC using a universal testing machine and an AE analyzer. Material and Methods. A metal jig considering the dimensions of premolars and molars was milled and 56-epoxy resin dies, which had a similar elastic modulus to that of dentin, were duplicated. According to manufacturer's instructions, the FRC beams with various thicknesses (2 to 4 mm) were constructed and veneered with the 1 or 2 mm-thick ceromers. The fabricated FPDs were luted with resin cement on the resin dies and stored at room temperature for 72 hours. AE (acoustic emission) sensors were attached to both ends, the specimens were subjected to a compressive load until fracture at a crosshead speed of 0.5 mm/min. The AE and failure loads were recorded and analyzed statistically. Results. The results showed that the failure strength of the ceromer/FRC inlay FPDs was affected by the total thickness of the connectors rather than the ceromer to FRC ratio or the depth of the pulpal wall. Fracture was initiated from the interface and propagated into the ceromer layer regardless of the change in the ceromer / FRC ratio. Conclusion. Within the limitations of this study, the failure loads showed significant differences only in the case of different connector thicknesses, and no significant differences were found between the same connector thickness groups. The application of AE analysis method in a fiber-reinforced inlay FPD can be used to evaluate the fracture behavior and to analyze the precise fracture point.
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문제 정의
The aim of this study was to investigate the most fracture resistible thickness combination of ceromer / FRC among the designs by varying the cavity dimensions. Because ceromer / FRC has the characteristics of a greenstick fracture without the catastrophic failure shown in ceramic materials, acoustic emission (AE) analysis was used to investigate the internal crack propagation simultaneously during the test.
제안 방법
Another limitation of this study was that the failure strength was recorded under the static load without a fatigue phenomenon induced by a dynamic load and a wet environment. Despite the many advantages of ceromer / FRC materials, there needs to be some caution when considering of fiber-reinforced inlay FPDs for clinical applications.
However, with an evaluation of the AE hit numbers, this point was later than the debonding point of the ceromer from the FRCZ which is believed to be a real' failure. In this study, the application of AE analysis methods can be used to evaluate the fracture behavior and analyze the precise fracture point. Therefore, predicting the failure of a fiber-reinforced inlay FPD should be supplemented with an AE analysis to detect the microfracture and initial internal crack propagation.
Therefore, a comparison of the failure load at the maximum peak stress point is an incorrect method for estimating the failure of a ceromer / FRC material. In this study, the failure load was set to a point where a decrease in the load coincides with an increase in the high amplitude AE hit numbers.
Subsequently, the lateral side of the specimens was examined by scanning electron microscopy (SEM) (LEO420, LEO LTD, Cambridge, UK) to investigate the surface crack characteristics at the failure site.
The failure strength of the inlay FPDs made of ceromer / FRC was recorded in order to investigate the most resistant dimension of inlay FPD with various thicknesses combinations. As a result the depth of the proximal box i.
The signal was then fed into an AE signal process unit (MIS-TRAS 2001\ where the AE parameters were analyzed using in-built software. Typical AE parameters such as the hit rate and the peak amplitude were investigated to determine the elapsing time.
대상 데이터
The fabricated specimens consisted of 7 groups with different ceromer / FRC ratios and different thicknesses of the connectors and isthmus (Table I). The specimens were luted with a Variolink II (Ivoclar-Vivadent, Shaan, Liechtenstein) resin cement on the resin dies and stored at room temperature for 72 hours (Fig.
of jigs. The specimens were fabricated with Targis / Vectris system (Ivoclar-Vivadentz Shaan, Liechtenstein). According to the manufacturer' s instructions, Vectris (FRC) beams with various connector thicknesses (2 mm (Group 1, 2)z 3 mm (group 3-6), 4 mm (group 7)) were con-structed on these dies.
데이터처리
Failure load lz 2 and the time to failure were analyzed statistically with ANOVA at the 95% confidence level and post-hoc analysis was performed using a Duncan multiple range test. In order to investigate the structural reliability of each group, Weibull modulus (m) and characteristic strength were also compared.
성능/효과
a ceromer / FRC material. This study showed that the low amplitude AE events representing the separation of the filler particles from the matrix26 were released immediately after loading, and the high amplitude AE events representing- the crack initiation were also released earlier than at the maximum peak stress. In addition, even at the failure load 2 peak stress, which is believed to be a starting point for interfacial crack propagation or FRC fracture, there were no 10 % loss of load in many cases.
후속연구
Despite the many advantages of ceromer / FRC materials, there needs to be some caution when considering of fiber-reinforced inlay FPDs for clinical applications. Further research into the cavity design and dimension will be needed in order to reduce the relatively high failure in a fiber-reinforced inlay FPD.
In this study, a short and long retainer showed a similar failure pattern and a similar AE hit number. However more research on the effect of length of the retainer will be needed.
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