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14 laboratory section DENTAL TECHNOLOGY, APRIL-JUNE 2022

HISTO-ANATOMICAL WAX-UP TECHNIQUE

DESIGNED TO IMITATE NATURAL POSTERIOR TEETH

NATURALLY SET IN WAX

NICO SQUICCIARINI AND SASCHA HEIN

Scientific research of the past 17
years has brought forth numerous
technological innovations that have
revolutionized traditional fabrication
processes in dental laboratories and
practices around the world. Despite
all the attractive and tempting
options of modern CAD/CAM technol-
ogy, valuable manual abilities –
particularly those learned during
dental training – have been sidelined.
The objective of this article is to
impart a passion for traditional
craftsmanship to young colleagues
and up-and-coming dental techni-
cians while opening up insights into
the histoanatomical architecture of FIG 1: Original illustrations from Michael Heinz Polz’s course script dated circa 1974. With his biomechanical
wax-up concept and “Occlusal Compass”, Polz left behind a spiritual legacy that
the marvel that is a “natural tooth”. made an impact on German dental technology and dentistry that lasts until this day.

INTRODUCTION
Around ten years ago, a biogeneric occlusal surface was used for the
first time to successfully lay the foundation for a mathematical
description of natural occlusal morphologies. This approach was
based on the analysis of thousands of intact tooth surfaces and objec-
tive algorithmic principles [1] . Thus, this description was rendered
without any specific prior knowledge about teeth, thereby enabling it
to encompass all previously applicable occlusion concepts [2] . Thanks
to continuing further developments in this innovative technique, it
has become possible today to efficiently fabricate functional, morpho-
logically accurate, naturally toothcolored restorations with relatively
little previous technical knowledge [3] . Although this development
represents a step forward in the professional profile of the dental tech-
FIG 2: Waxing-up technique based on the NAT system developed by Dieter Schulz in 1997 (prac-
nician, efforts should still be made to ensure that the manual skill of
tice work/piece by S .Hein). It is notable that the functional areas on the occlusal surface
being able to contour and shape a tooth wax-up in all its details and described by Dieter Schulz in the 1990s have meanwhile been further systematized into an
original size, is not permanently relegated to the sidelines. Indeed, a internationally widely accepted color code.
high degree of manual skill will always be required to truly be able to
chromatically and morphologically bring a CAD/CAM restoration to
consummate finalization. The waxup technique described here pro-
vides the opportunity to acquire that fundamental knowledge of tooth
morphology.
However, if the aim is to implement this knowledge in tooth-col-
ored materials, not only is knowledge about the external shell of the
tooth – its exomorphology – essential.
It is also important to understand the three-dimensional, topo-
graphic structure of the histo-anatomical complex existing in natural
teeth since these topographies have a significant influence on the
optical properties of any restoration [3] . FIG 3: In order better understand the topographical structure of the natural tooth’s histo-
anatomical complex, it is helpful to start by analyzing the three-dimensional distribution of
enamel and dentin. A pronounced dentin-concavity can be seen at the upper buccal surface.
HISTORICAL RETROSPECTIVE This concavity is located at the transition of the middle third and represents a transition to the
The origins of endeavours to better understand the morphology and, occlusal third in upper and lower molars and premolars. Through this, a “sigmoid curve” (con-
above all, the functional relationships of natural dentition date back vex enamel/concave dentin) is created.