MICROLEAKAGE AND THE METHODS OF INVESTIGATION A [629273]

MICROLEAKAGE AND THE METHODS OF INVESTIGATION – A
SYSTEMATIC REVIEW
PERCOLAREA MARGINALĂ ȘI METODE DE INVESTIGARE – O
ANALIZĂ SISTEMATICĂ

Adrian Tudor Stan1, Cosmin Sinescu1, Meda Lavinia Negruțiu1, Mihai Romînu1
1 Facultatea de Medicină Dentară, Universitatea de Medicin ă și Farmacie ”Victor Babeș”
din Timișoara,
Adresa:
Universitatea de Medicină și Farmacie,Bulevardul Revoluției din 1989, nr.9, Timișoara

Keywords: microleakage, OCT, interface, integrity
Cuvinte cheie: percolare, OCT, interfa ță, integritate

Abstract

Longevity of dental restorations is dependent on the interface between the restorative
material and tooth structures. The oral cavity can create a rather severe challenge for
the composite bonds to appear , that may lead to the formation of defects at the tooth –
restor ation interface, that are very favorable to th e passage of fluids, molecules and
mainly bacteria, a process known as marginal micro leakage .
This study investigates the usefulness of different n ew approaches to determine the
microleakage volume in association with dental restorations and the corresponding
marginal adaptation that can translate into deficiencies and gaps at the interface
between the two structures.
One of the traditional and refe rence methods used is the dye penetration syste m which
uses 2% methylene blue and it is used as a standard referring rule of comparison with
the newer methods which can be the OCT – Optical Coherence Tomography, microCT,
TEM – Transmission Electron Microsc opy, SEM – Scanning Electron Microscopy,
confocal microscopy. All of them have their advantages and disadvantages and also
newer methods of investigation are appearing in the research field.

Rezumat

Longevitatea obturațiilor depinde de interfața apărută la nivelul materialului compozit și a
structurii dentare. Cavitatea orală poate ridica dificultăți pentru adeziune, ceea ce poate
duce la apariția unor defecte la interfața dinte -restaurare, defecte ce sunt favorabile
pasajului de fluide, molecule și în p rincipal bacterii, proces numit percolare marginală.
Acest studi u investighează gradul de folosință a unor metode diferite de determinare a
volumului percolării marginale și a adaptării marginale , care pot duce în final la
deficiențe și defecte.
Una dintr e metodele de referință folosite este testul penetrării colorantului ce folosește
albastru de metilen 2% – folosit ca metodă standard pentru a compara cu metode mai
noi apărute, cum ar fi OCT – Tomografia în Coerență Optică, microCT, MEB –
Microscopia Elec ronică cu Baleiaj etc. Toate acestea au avantajele și dezavantajele lor,
iar noi metode de investigare apar mereu în domeniul cercetării științifice.

Microleakage and the methods of investigation

Dye penetration inspection is a very widely used and low -cost inspection method to
locate the surface defects of the tooth -restoration interface. The defects that can appear
may as well be cracks, porosities even fatigue and contration fissures of the material. It
is based upon capi llary action, where low surface tension fluid penetrates into surface –
breaking discontinuities.
The most used method in the dental field is the dipping test, but also brushing can be
used. After and adequate time for the penetration to occur, the excess i s removed and
inspection is performed under ultraviolet or white light, depending of the dye used –
fluorescent or non fluorescent (visible).
One of the main advantages of the method is the speed of the testing and the low price.
Disadvantages can include the detection of only surface flaws if we want to used the non
invasive method, but this can be overcome by tooth sectioning which axis may be
needed.
Only l imited training is required for the operator. A well cleaning is necessary to assure
that the surfa ce is free of contaminants and any gaps or defects present are dry and

clean . Some of the cleaning methods have the possibility to be detrimental to test
sensitivity – acid etching to remove smearing and re -open the defect may be necessary .

X-ray microtom ography (microCT), like tomography and x -ray computed tomography,
uses x -rays to create cross -sections of the teeth, that can be used to recreate a virtual
model of the tooth structure (3D model) without destroying the original object – a non
invasive meth od. The prefix micro (symbol: µ) is used to indicate that the pixel sizes of
the cross -sections are in the micrometre range, so it has a very high resolution in
determining the defects at the tooth -restoration interface.
To reveal any interfacial gaps or d ebonding between the dental restoration and the tooth
structure after curing, the specimens will be submerged in a silver nitrate solution that is
radiopaque.
Advantages of microCT: allows for extremely high -resolution, 3D imaging and non –
destructive way of investigation. There is no sectioning or sample preparation needed
and the samples can be frozen or fixed. Since Micro -CT is non -destructive, other
examinations may be carried out after, thereby increasing the amount of data per
sample .

Optical coherence tomography (OCT) is an entrenched medical imaging technique. It
uses a light source to capture micrometer -resolution, 3D images from within the tooth
structure . Optical coherence tomography is based on low -coherence interferometry,
typically empl oying near -infrared light. The relatively long wavelength of the light allows
it to penetrate into the scattering interface of the dental restoration.
The OCT has a high spatial resolution, real -time imaging and also 3D reconstruction is
available. It lack s in penetration depth and scanning range, but in addition a confocal
microscope can be used and to make a comparison between probes. OCT is not onl y an
“imaging tool” but also an important and non -invasive method for early detection of
caries and other or al diseases.

Scanning electron microscope (SEM) is a type of electron microscope that produces
images of a tooth structure by scanning it with a focused beam of electrons. The
electrons interact with atoms in the sample, producing various signals that co ntain
information about the sample's surface t opography or defects . SEM can achieve
resolution better than 1 nanometer.
SEM allows the visualization of images at high magnification (50x – 10000x and above).
In this technique, an ele ctron beam scans the sur face of the sample to pr oduce a variety
of signals, the characteristics o f which depend on many factors, including the ene rgy of

an electron beam and the nature of the sample, since a beam of electro ns hit s the
sample and the response is collected by a det ector.
SEM can be seen as a golden standard for determining the microleakages in the
marginal area of direct and indirect placed adhesive restorations.

Conclusions
To review the data from the literature, some conclusions can be drawn:
 Each one of the methods of investigation have their advantages and
disadvantages
 The key to increase the amount of data per sample is to use different methods of
investigation.

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