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Ceramir Crown & Bridge (Ceramir C&B) is the main product of DOXA AB. It is the first ever invented product based on the Ceramir technology which belongs to the material group Nanostructurally Integrating Bioceramics i.e., NIB (H. Engqvista et al., 2001).
Ceramir hardens by dissolving with water first which wets the tooth, and continues to recrystallize as nanocrystalline hydrates which precipitates on the wall of the tooth, creating a basic pH (L. Hermansson et al., 2003). This mechanism is based on surface energy and mechanical interlocking at Nano-level, and this whole process is called nanostructural integration. Ceramir chemically resembles hydroxylapatite, which is a major component of teeth and this helps ceramir to match natural teeth in its composition. It has the capability to create a natural zone of contact without any mechanical or thermal stress for which its unique properties are very important (L. Hermansson et al., 2006).
Properties and sealing:
To understand sealing mechanism it's important to discuss mechanical properties, thermal properties, and physical properties of ceramir;
1. It has a basic pH which is helpful to maintain a neutralised stable environment even when acidity increases inside the mouth (L. Hermansson et al., 2003), and it is an important requirement for the material to remain bioactive, by means of which it produces hydroxyapatite on the surface whenever it comes in contact with phosphate solutions (Pameijer CH, 2009). Hydroxyapatite has some special properties as follows;
a. Hydroxyapatite decomposes at temperature between 800-1200Â°C, and is an unstable compound thermally.
b. Large volume of hydroxyapatite fails to retain long term load bearing, and doesn't have mechanical strength.
2. It takes over the properties of hydroxyapatite when it comes into contact with phosphates and crystallizes naturally into a Nano crystalline structure (L. Hermansson et al., 2003).
3. It interacts with the tooth tissue through the mechanism of Nano structural integration, and remains bioactive in the oral environment (L. Hermansson et al., 2003).
4. Physical properties like hardness, flexural strength, solubility are prominent, and are very important for biocompatibility (Pameijer CH, 2009).
5. In vivo studies on primates supported by X-rays from human on clinical trial has revealed that Ceramir C&B is a material with extremely non-irritating and bland characteristics in the oral environment which makes it more widely used material (Pameijer, C.H et al., 1988). It stands out when compared to other materials. There are histological evaluations and clinical trial reports which prove its non-irritant properties (Pameijer, C.H et al., 1988).
6. The material does not shrink at all, has resistance to impact, abrasion and has a lifetime serving quality (R J Mangabhai et al., 2001).
7. Since it is calcium aluminates based system, the turnover of water is very high during the hardening process; this shows it binds lots of water inside the material throughout the process of hardening. This amount of water is directly proportional to the strength of the material, and is several times greater than that of other calcium phosphate systems. It also causes a large variation in its viscosity and composition (R J Mangabhai et al., 2001).
8. It has a very rapid hardening capacity which is a most important requirement in dental materials. The hydrates formed by nano crystallization contain ions which are formed from the dissolved chemical powder (material) and water. When the concentration of the ions reaches a certain level, the material forms a permanent structure. The newly formed material has two hydrates; Katoite and Gibbsite (H. Engqvista et al., 2001).
9. Katoite is chemically calcium alumina hydrate and built of crystals each with size 10-40 nanometres. Gibbsite is chemically aluminium hydroxide and forms crystalline gibbsite over time. And this material attaches to the tooth by the Nanostructural integration as explained before (H. Engqvista et al., 2001).
10. Ceramir has natural thermal characteristics of teeth like, thermal conductivity and elastic modulus. It has thermal properties similar to enamel and dentine, which helps to minimise the effect of thermal shock when it faces sudden temperature change. And it is able to move along with the tooth, avoiding the formation of gap (Pameijer CH, 2009). The thermal properties of ceramir and other dental materials are tabulated below:
11. For a good contact between the material and the dental tissue viscosity and rheology are also important. There are many different mechanisms by which materials attach to tissue like, creation of mechanical lock between material and tooth irregularities, by use of adhesives, and by chemical bonding (Pameijer CH, 2009).
The different clinical investigations resulted in stating that the powder and liquid component mixing was easy. It was a smooth procedure to follow, its working and setting time were around 2 - 2.5 and 4 - 5 minutes and relatively were superior to other cements generally used in clinics (S R Jefferies et al., 2009).
Clinical studies were carried out for a year with the dental cement Ceramir C&B, on 38 crowns and 17 patients with bridge abutment. Their setting rimes, working times and handling characteristics were recorded during this period (S R Jefferies et al., 2009). Gingival inflammation (GI), Pre-cementing and Post-cementing sensitivities including gum tissue reactions, discolouration and integration of the material were also analysed and reported. All the patients were recalled for clinical examination on a constant time period interval, like 30 days, 3 months, and 6 months. One year examination of the material was done on fifteen patients. Researchers found that the working time and setting time of the material was found to be amazingly inside limits and it was an easy process of removal of the cement as well. Though 4 patients reported complaints immediately about the post-cementing sensitivity, but however it later vanished within a month by an occlusive alteration (S R Jefferies et al., 2009).
In a time period of one year no retention failures or post-cementing sensitivity was reported. All the crowns and cementing process were rated Excellent by all the patients on the clinical trials. The Gingival inflammation, tooth sensitivity, Pre- and Post-cementing problem scores were decreased during this time period of study. And this study period also revealed absence of secondary caries and discolouration of the tooth margin. Thus, the new cement in the market; Ceramir C&B was found to be successful in the clinical trials, and was performing favourably for permanent cementation as a luting agent (S R Jefferies et al., 2009).