Naslov
Chemical Durability of Feldspatic Ceramic: A New Approach

Autori
Živko-Babić, Jasenka ; Jakovac, Marko ; Ćurković, Lidija ; Mehulić, Ketij

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Abstract Book of 27th Annual Conference of EPA 2003 / - Ženeva, 2003

Skup
Annual Conference of EPA

Mjesto i datum
Ženeva, Švicarska, 01.09.2003. - 05.09.2003

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Chemical durability; Feldspathic ceramics

Sažetak
In general, dental ceramics are considered to be chemically inert1-3. However, the properties of materials should not be generalized1, 3. Today, the number of new released ceramics are growing and with them the need for its evaluation. The purpose of this investigation was to analyze one type of feldspatic ceramic according to ISO Standard4 and to analyze its chemical durability in longer measuring period (7 days). Ten specimens of IPS-Classic ceramic (Ivoclar-Vivadent, Shaan, Liechtenstein) were prepared using plexiglass mould (10x10x2 mm), placed on top of platinum foil and backed. The surfaces of specimens were ground using 500- and 1000-grit (18&micro ; ; m) SiC-paper on rotating disc at 150 r.p.m. and then glazed. The samples were ultrasonically cleaned (Bransonic 220) and dried at 150&plusmn ; ; 5 oC for 4 hours (Drier, Instrumentaria, Zagreb, Croatia). The weight of the samples (&micro ; ; g) (Analitical scale, Ohous, Analytical plus) was measured and the samples were placed in plastic boil (PP, 25, 0 ml) filled with 4% acetic solution (ISO- Standard 6872 for dental ceramic) at temperature of 80oC. After sixteen hours of immersion, the specimens were cleaned with distilled water, dried and their weight was checked again. Weight loss was calculated (&micro ; ; g/cm2). Once again the same specimens were placed in 4% acetic acid solution for period of seven days. After 7 days the specimens were cleaned and their weight was measured for the third time. IPS-Classic showed good results after 16 hours of immersion (9.4 &micro ; ; g/cm2) and its chemical durability was well below the limit allowed by ISO-Standard 6872 (2000 &micro ; ; g/cm2). In period between 16 hours and seven days of immersion the weight loss was three times higher (28.1 &micro ; ; g/cm2). The weight loss after 7 days of immersion was 37.5 &micro ; ; g/cm2. In literature there is a fact that immersion in artificial saliva at 22&ordm ; ; C for 22 years would be required to produce the same degree of surface dissolution as an exposure to 4% acetic acid solution at 80&ordm ; ; C for seven days5. From this fact it could be calculated that 16 hours of exposure in acetic acid (according to ISO-Standard) produce the same degree of surface dissolution as an immersion in artificial saliva at 22 for approximately 2 years. That time is well below of maximal functional durability for ceramic restoration in oral cavity. Oral cavity is also more aggressive than artificial saliva at 22&ordm ; ; C. The results in this study, for both measured periods, do not exceed the limits allowed by ISO-standards but the weight loss after seven days of immersion is three times greater than the weight loss after seven days. This fact has to be considered in cases with great weight loss of ceramic after 16 hours of immersion6. The same is with possible toxic effect of eluted ions from dental ceramics7, 8. The question derives, does the time for the investigation of chemical durability of dental ceramic according to ISO-Standard really optimal.

Izvorni jezik
Engleski

Znanstvena područja
Kemija, Dentalna medicina

POVEZANOST RADA