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Coffee is one of the world’s most popular beverages; however, it is known for its tooth staining properties. A study has now tested how various CAD/CAM materials reacted to immersion in coffee. (Photograph: Vitelle/Shutterstock)
0 Comments Mar 28, 2017 | News Asia Pacific

Latest CAD/CAM materials less likely to be stained by coffee than conventional resins

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BANGKOK, Thailand/TOKYO, Japan: With the development of new materials and technology in dentistry, expectations for durable and aesthetically pleasing restorations are ever increasing. In a recent study, researchers from Thailand and Japan investigated how sensitive various restoration materials were to discoloration from coffee.

Leaving a lasting impression may be desirable in a job interview, but is certainly not what one wants from one’s morning coffee. Just like natural teeth, restorative materials are susceptible to discoloration from certain foods and beverages with high staining properties, including coffee, tea and red wine. In order to avoid discoloration over time, surface quality is thus essential for the success of restorative treatments.

New CAD/CAM composite resin blocks are industrially polymerised under standardised parameters at high temperature and pressure to achieve optimum properties at the microstructural level and a high degree of conversion. As a result, material characteristics have improved compared with direct restorative composite resin.

In the study, researchers from the Tokyo Medical and Dental University in Japan and the Chulalongkorn University in Bangkok aimed to evaluate how modern composite resin block materials developed for CAD/CAM systems react to coffee exposure compared with conventional resin materials.

The researchers measured the change in colour in eight CAD/CAM blocks, including five composite resin blocks (Block HC, Shofu; CERASMART, GC; GRADIA Block, GC; KZR-CAD Hybrid Resin Block, Yamamoto Precious Metal; Lava Ultimate, 3M ESPE), one hybrid ceramic block (VITA ENAMIC, VITA Zahnfabrik), one PMMA block (Telio CAD, Ivoclar Vivadent) and one feldspathic ceramic block (VITABLOCS Mark II, VITA Zahnfabrik), and four conventional composite resins. The latter included one hybrid composite (CLEARFIL AP-X, Kuraray), one micro-filled composite (Durafill VS, Kulzer) and two nano-hybrid composites (ESTELITE SIGMA QUICK, Tokuyama Dental; Filtek Supreme Ultra, 3M ESPE).

They created 10 mm discs from each of the restorative materials and then calculated the discs’ initial colour measurements before placing them in an instant coffee solution, which was changed daily. Colour changes were measured after one day, one week and one month.

The results showed that the coffee solution significantly discoloured all of the discs over time; however, CAD/CAM materials were generally less affected than the conventional resin materials. After one month, the change in colour of CAD/CAM composite resin blocks and restorative composites ranged from 1.6 to 3.7 and from 2.1 to 7.9, respectively. According to the researchers, only one material, Durafill VS, was not significantly more discoloured after one month than after one day.

However, in testing whether the coffee stains were removable through polishing, the colour of all of the materials, except for the GRADIA block, was restored after polishing with prophylaxis paste for 20 seconds. Of the conventional composite resins, Durafill and Filtek Supreme Ultra still showed some noticeable discoloration after polishing.

The authors noted that, owing to the study’s in vitro design, it is unknown how external factors, including regular toothbrushing, might affect the long-term discoloration of the materials when used in patients. They further pointed out that one month of immersion might have exaggerated the results beyond what would be seen in vivo, as immersing materials in coffee for one week is the equivalent of about seven months of coffee drinking.

The study, titled “Discoloration of various CAD/CAM blocks after immersion in coffee”, was published in the February issue of the Restorative Dentistry and Endodontics journal.

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