Ivoclar Vivadent SR Nexco Paste - Manual (Page 11)

11
Application procedure
– Shade Determination | Pr
eparation Guidelines and Minimum Thickness
PrEParatIon GUIdELInES and mInImUm LayEr tHIcKnESSES
Successful results can only be achieved with Sr nexco veneering material if the guidelines and minimum
layer thicknesses are strictly observed.
as framework-free Sr nexco restorations are placed using an adhesive cementation method, a tooth-
conserving and defect-oriented preparation technique can be used.
Inlays and onlays
Static and dynamic antagonist contacts must be taken into consideration. the preparation margins
must not be located on centric antagonist contacts. a preparation depth of at least 1.5 mm and an
isthmus width of at least 1.5 mm must be observed in the fissure area. Prepare the proximal box with
slightly diverging walls and observe an angle of >90° between the proximal cavity walls and the
prospective proximal inlay surfaces. for inlays with pronounced convex cavity walls without adequate
support by the proximal shoulder, marginal ridge contacts should be avoided. round out internal edges
and transitions in order to prevent stress concentration within the composite material. Eliminate the
proximal contacts on all sides. do not prepare slice-cuts or feather edges.
for onlays, provide at least 2 mm of space in the cusp areas. on the vestibular side, prepare a bevel
(10°–30°) to improve the esthetic appearance of the transition between the composite and the tooth.
onlays are indicated if the preparation margin is less than approximately 0.5 mm away from the cusp
tip, or if the enamel is severely undermined.
Anterior crowns
Evenly reduce the anatomical shape and observe the stipulated
minimum thickness. Prepare a circular shoulder with rounded inner
edges or a pronounced chamfer of at least 0.8 mm. In the anterior
region, reduce the labial and/or palatal/lingual surfaces by at least
1.0 mm. reduce the incisal crown third by at least 1.5 mm. design
transitions in such a way that no angles or edges are present.
≥1.5
6°
>90°
60°–80°
≥1.5
≥2.0
≥1.5
6°
10–30°
≥1.5
0.8
0.8
≥1.0
1.5
>1.0