The Influence of Using Rotary and Ultrasonic Instruments on The Surface Roughness of Finishing Line and Marginal Adaptation In Metal-Porcelain Restoration

Abstract

Fixed dental prostheses that is still popular today is metal-porcelain restoration due to its strength and affordable price and
indicated more to the cases that require strength and longevity. One of the important procedure in making porcelain metal
restorations is dental preparation. Rough surface preparation especially finishing lines can cause the adaptation of the
restoration to the tooth thatis reduced and cause the formation of gaps on the tooth surface and restoration. Restoration with
an ill fitting causes marginal microleakage and risk of secondary caries, thus causing failure in making metal-porcelain
restorations. The smooth surface of the gingival margin has an important role in maintaining the accuracy at the clinical and
laboratory stages. A smooth surface with good finishing line contours can help in getting good clinical impression. At the
laboratory stage, it allows porcelain lift-off from the dye and eliminates unsupported tooth structure, which can rupture from
the dye causing disruption during fixing, as well as marginal gaps. Smooth finishing line can increase surface wettability when
cementing to avoid the formation of cracks, margin leakage, and dissolved cement which can cause caries and restoration
failure. Ideally, after preparation, the surface of the preparation results should be smoothed. Surface finishing of preparation
can be done with rotary or ultrasonic instruments. The purpose of this research was to determine the effect of the use of
finishing instruments: fine diamond bur, tungsten carbide finishing bur, whitestone bur and UDTs finishing kit on the surface
roughness of the finishing line and marginal adaptation in metal-porcelain restoration and the relationship between surface
roughness of the finishing line using the instrument finishing to marginal adaptation to metal-porcelain restorations. This
research type is an experimental laboratory. Overall a total of 40 samples are divided into 2 groups for surface roughness (20
samples) and marginal adaptation (20 samples). Each group was divided into four treatment groups which were prepared using
coarse diamond bur followed by finishing with fine diamond bur, tungsten carbide, dura whitestone, UDTs finishing kit. The
surface roughness measurement finishing line using the Mitutoyo Surftest Profilometer SJ-310 Series Handheld Roughness
Tester, Japan. Measurements were done 3 times at the marked surface points on the sample. The average of the 3
measurements was calculated in µm. The stylus runs 1mm from the external finishing line. Measurement of marginal gap on
the metal-porcelain crown is using a stereomicroscope (Zeiss Stereo Discovery, V12, Germany). Four reference lines were made
on the tooth, the lines on the tooth wasmid-mesial proximal, mid-distal proximal, mid-palatal, and mid-buccal, with each
measurement on the line was done 3 times so that the total measurement in 1 sample was 12 times. Measurement of marginal
adaptation with a 12.0x magnification stereomicroscope using a computer with the Axiovision Rail software. 4.8. The results of
univariate analysis found that the greatest surface roughness of finishing lines was using a fine diamond bur at 2.32
, followed by whitestone 2.26 , tungsten carbide 1.72 and the smallest using UDTs
with an average at 1.47 .Based on the ANOVA test results, the value of p = 0.001 * (p <0.05) can be concluded that
there is a significant influence of the finishing instrument on the surface roughness of the finishing line. The results of univariate analysis found that the greatest average marginal adaptation is using a fine diamond that is equal to 20.60 , then
followed by whitestone instrument 16.91 , tungsten carbide 13.39 and the smallest using UDTs,
with an average of 6,39 . Based on the ANOVA test results, it is seen that the value of p = 0.001 * (p <0.05), it can
be concluded that there is a significant influence of finishing instruments on the marginal adaptation of metal-porcelain
restoration. Spearman Correlation Test to determine the strength of the relationship between surface roughness of the
finishing line and the marginal adaptation of the metal-porcelain restoration based on the finishing instrument, by looking at
the correlation value (r). All instruments were positive for the direction of the strength of the roughness of the surface finishing
line and the marginal adaptation of the metal-porcelain restoration based on the finishing instrument, meaning that the greater
of surface roughness value, the absolute marginal discrepancy value would also be greater (marginal adaptation metalporcelain restoration isbad), however significant was the whitestone and fine diamond instruments whose strength was very
strong (r = 0.9, p value = <0.05). The research can be concluded that fine diamond which is often used in daily clinical life turned
out to produce the highest roughness compared to finishing tungsten carbide, whitestone and UDTs finishing kit. UDTs bur from
ultrasonic instruments produce the smallest surfaceroughness finishing line and the best marginal adaptation to restoration
(smallest marginal gap) compared to rotary instruments (fine diamond bur, tungsten carbide finishing, and whitestone). UDTs
finishing kits are appropriate for daily clinical use especially for sub gingival case preparation because they can produce the
smallest surface roughness value and marginal gaps. The ultrasonic movements do not injure the periodontium tissue.