Tips & Tricks Espertise™

Tips for achieving excellent marginal adaptationTo achieve an excellent margin when placing an inlay, onlay or a full coverage crown and to avoid white lines – which can result in discolouration over time – we recommend the following:

1. Ensure precise fit of the restoration to avoid irregular breaks when removing the excess

Small gaps (< 80 µm) enable a clean break (see Fig. 1) of the cement at the margin. Big gaps (Fig. 2) can result in irregular breaks which can create white lines. The optical effect of white lines is due to unequal light scattering. Over time plaque build-up on rough surfaces may cause additional discolouration.

Final polishing of the marginal area after careful removal of excess cement also helps to avoid discolouration.

Perfect result White lines at margin Discolouration at margin over time

Tack cure

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Ideal fit – small gaps

Fig. 1 Fig. 2

Poor fit – wide gaps

Tack cure

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Remove excess

smoothsurface

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Remove excess

Roughsurfacedue toirregularbreaks

3M ESPE AG · ESPE Platz82229 Seefeld · Germany

E-Mail: info3mespe@mmm.comInternet: www.3mespe.com

3. Remove excess carefully to avoid cement on uncut enamel

Good adhesion is only possible on cut enamel. In case of cement overlap on uncut enamel (Fig. 6), adhesion will be compromised. If adhesion is compromised, moisture can infiltrate into the small gap between cement and uncut enamel and cause white lines and discolouration over time.

Final polishing of the marginal area after careful removal of excess also helps to avoid discolouration.

2. Use glycerine gel to achieve optimal polymerization of the cement surface

Cover the cement with glycerine gel (Fig. 3) to create an air block which ensures the complete polymerization of the cement surface in the self cure mode. Oxygen can inhibit curing at the surface (Fig. 4). A cement that is not fully polymerized may absorb water which might result in increased opacity or staining. Additionally, the mechanical properties will be compromised which may result in washouts and poor marginal integrity.

Good excess removal Poor excess removal

Fig. 5 Fig. 6

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With gel Without gel

Fig. 3 Fig. 4

Glycerine GelOyxgen

Inlay Inlay

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Completelycured

Not completelycured materialdue to oxygeninhibition

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Unpreparedarea

Preparedarea

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Contact tounpreparedarea

Discolouration