Student Rat Daniel

Lecturer dr Șoaita

Claudia

Full coverage crowns are one of the most common fixed prosthetic treatments in all over the world, and for many years were made by dental technicians.

Recent technological advancements have introduced alternatives to conventional methods through the use of Computer Aided Design-Computer Assisted Manufacturing(CAD-CAM).

Is a small space between the surface of the prepared tooth and the internal surface of the crown (cement space). Near the gingiva this space is referred to as the marginal gap.

The marginal gap should be as minimal as possible for clinical success.

It has been shown that a width of less than 120μm* is clinically acceptable.

*Munir Tolga Yucel, Filiz Aykent, Mustafa Cihat Avunduk. In vitro evaluation of the marginal fit of different all-ceramic crowns. 21 June 2012. P 225-1

Poor marginal adaptation leads to: -increased plaque retention and subsequent

changes in the subgingival microflora leading to periodontal disease and secondary caries.

Additionally, a large marginal gap leads to increased exposure of the luting agent to the oral environment which may cause increased microleakage and cement dissolution.

The aim of this in vitro study was to compare the marginal adaptation of different crowns fabricated with digital and conventional method.

Conventional

CAD-CAM System

Milled Co-Cr

Zirconium

Milled wax with lost-wax method

Materials and methods

A system was created allowing marginal gap measures in the same points for each subject.

Therefore were obtained twenty measures for each crown by direct visualization using a microscope.

CONVENTIONAL ZIRCONIU Co-Cr FREZAT CEARA FREZATA

P1 360 63 69 115

P2 85 24 35 44

P3 67 16 21 16

P4 85 49 59 70

P5 46 33 40 60

P6 45 9 5 13P7 234 80 95 92

P8 313 115 122 138P9 141 80 79 121

P10 88.5 72.5 85 70.5

P11 113 51 69.5 81.5

P12 132 79 79.5 90.5

P13 167 54.5 47.5 71

P14 265 30 43 46

P15 179 121 121 112

P16 85 30 58 65

P17 67 52 45 62

P18 70 35 48 97

P19 82 60 80 100

P20 109 42 67 71

The hypothesis was confirmed, the crowns made with CAD-CAM system turn out to be much better than the crowns made with conventional method

The values obtained for those three crowns are below the accepted limit of 120 µ

Similar researches have been made by others authors , Per Svanborg 2014, Anders Ortorp 2010, Hisham A. Mously 2014, results obtained by us were similar to them.

Based on the obtained results we can say the following:

»different manufacturing techniques affect marginal adaptation

»crowns obtained using CAD-CAM system have a much better marginal adaptation than those obtained by conventional method

»there were also differences between the results obtained for the crowns fabricated with CAD-CAM, but those differences were small

»as expected, zirconium proved to have the best adaptation