setting benchmarks – designing the future

Issue 15 | 2016
The CAMLOG Partner Magazine
logo 39 • the CAMLOG Partner Magazine • November 2016
Dr. Peter Gehrke, Ludwigshafen, DT Carsten Fischer, Frankfurt a. M.
The authors have been involved with CAD/CAM abutments for more than ten years and their work and
publications have contributed to the paradigm change in the manufacturing of implant abutments. In this series
of articles they summarize their experience in surface topography. After describing fabrication precision and
bonding of two-part abutments in the first part of the publication (logo 14), the second part focuses on the
surface topography of abutments in the submucosal region. The third part is devoted to hygiene measures
for abutments.
Presently there is great debate on the
manufacturing of customized abutments
– and that is a good thing! The topics
fit, cleaning and surface topography
of the individual structures are highly
controversial. These aspects must be
considered more and more in daily
routine. We need reproducible rules,
for example, for the fabrication and
bonding of titanium bases (see Part 1,
logo 14), for surface topography in the
submucosal region (Part 2) and for a safe
hygiene protocol (Part 3, logo 16). This
article answers questions on: what are
the decision parameters for a production
concept – in-house or outsourced – which
lead to fulfillment of the desired outcome
quality? Does the industrially fabricated
abutment need to be reworked? Are
there concrete specifications on the
roughness of the abutment in the submucosal region and how can these be
complied with?
logo 39 • the CAMLOG Partner Magazine • November 2016
Fig. 1: Overview of scanning electron microscope (SEM) cross-section for a DEDICAM hybrid abutment. Colored white: ZrO2-CAD/CAM abutment on titanium
base. Colored red: internal bonding joint with the measuring points L2 - L7 and the
external bonding joint (contact with mucosa) with measuring points L1 and L8.
Fig. 2: Magnification of the external bonding gap (L1) with a size of 0.21µm. The
gap of the bonding joint is therefore more than half as small as for adhesive mounting of crowns on teeth, where a bonding joint of 50µm is regarded as being ideal.
Figs. 3a and 3b: DEDICAM-fabricated (left image) and lab-fabricated (right image) zirconium oxide sleeve. Both approaches can achieve high-precision results.
Precision and bonding gap
State-of-the-art dental technology is
able to fabricate precision-customized
abutments with modern milling machines
and advanced know-how. However, one
should take into account: the procedure
or the quality of the result respectively,
depend on numerous influencing factors,
for example, calibration of the milling
machine, milling cutter or sintering
process. Predictability and reproducibility
are of utmost importance, both for
fabrication in the own lab or in centralized
fabrication (e.g. DEDICAM). For us, the
competent "extended workbench" of an
external partner delivers equally perfect
results – day by day. The guarantee for
maximum safety of a hybrid abutment
lies in the fit of the abutment sleeve on
the titanium base. Next to bonding itself,
the bonding gap plays an elementary
role. To achieve a secure bond according
to our studies, the bonding gap must be
In a clinical investigation we compared
the bonding gap between the titanium
base and the zirconium oxide sleeve
of in-house fabricated abutments with
DEDICAM structures. Images taken under
a scanning electron microscope (SEM)
showed the discrepancies which can
occur if perfect lab conditions deviate
(Figs. 1 to 3) [3].
logo 39 • the CAMLOG Partner Magazine • November 2016
Case study: Dr. Rafaela Jenatschke, Frankfurt a. Main / DT Carsten Fischer, Frankfurt a. Main
Figs 4a to 4d: Sequences of prosthetic implant restorations for posterior teeth with customized implant components for forming the emergence profile. For us, the forming
of the emergence profile with customized gingiva formers is a necessary step in the protocol on the route to an optimal esthetic result.
Case study: Dr. Rafaela Jenatschke, Frankfurt a. Main / DT Carsten Fischer, Frankfurt a. Main
Figs. 4e to 4g: After forming, the definitive zirconium oxide CAD/CAM abutments and the ceramic crowns are inserted. The protocol described in the article for ideal
surface topography and surface cleanliness was applied when fabricating the customized hybrid abutments.
The effect of micro-design on the
health status of soft tissue
Two aspects need to be discussed when
looking at the surface topography of the
basal region (Fig. 4).
in the lab (excess adhesive, wear from
rubber polishers etc.). Pre-assembled
abutments can also be contaminated.
1. Surface topography: Whether milled
in the lab or coming from centralized
manufacturing, there is always a risk
that the abutments are too rough in
the basal region. On the other hand,
surfaces which are too smooth are
This tandem of facts makes it necessary
to subject all customized CAD/CAM
abutments to subsequent reprocessing.
This needs to follow controlled and
validated processes, as described in the
following. We are of the opinion that
this should not only apply to customized
abutments, but to all prosthetic implant
components – including pre-assembled
catalog items.
2. Surface cleanliness: Contamination of
the surface can occur in centralized
manufacturing (coolants, milling chips
etc.) as well as during further processing
It is the responsibility of the treatment
team to assess the biocompatibility of
the materials used, both from a dental
and a material point of view. We have
examined different abutment surfaces
and observed considerable differences in
manufacturing quality. The surface quality
of individual abutments is to be assessed
in terms of the following aspects: plaque
deposit, bacterial adhesion, potential for
accumulation of peri-implant mucosa.
Surface topography
Optimal adhesion of the peri-implant
mucosa is desirable for a successful longterm result. A decisive role is played here
by the surface of the implant abutment
in the transmucosal region. The goal
is solid adaptation of the peri-implant
mucosa. However, we also know that this
region is fragile and can react sensitively
to toxic or mechanical influences. Using
logo 39 • the CAMLOG Partner Magazine • November 2016
optical profilometry (focus variation
microscopy), we examined the microdesign below the shoulder of CAD/CAM
abutments of various manufacturers in
a study. The objective was to define the
ideal topography and surface roughness
Fig. 5: The traffic light system for the classification of roughness in the basal region could be established
as follows [1]:
Rough = > 0.41 µm (red: increased risk of plaque accumulation)
Smooth = < 0.2 µm (amber: reduced accumulation of fibroblasts)
Medium rough = 0.21 – 0.4 µm (green: perfect)
Today, we can presume that there is a
threshold value at which bacterial and
plaque accumulation on the surface is
low while at the same time promoting the
accumulation of fibroblasts (Fig. 5). If the
surface is too rough, this bears the risk of
increased plaque accumulation. However,
if the surface is too smooth, the fibroblasts
of the peri-implant mucosa cannot
"attach" optimally. Therefore a medium
roughness value (in µm: Ra = 0.21-0.40)
is regarded as the ideal surface. During
the investigation on CAD/CAM fabricated
abutments, a ten-fold higher surface
roughness was detected in parts. In other
words, this requires reworking to achieve
the mean roughness value. According to
our validated processing protocol
(see surface cleanliness), the CAD/CAM
hybrid abutments offer optimal roughness
and demonstrate good conditions for the
desired accumulation of peri-implant
Consequence for lab and practice
Fig. 6: Reworking of the surface in the basal, submucosal region with special rubber polishers. The desired
residual roughness of 0.2-0.4 µm was achieved.
In order to generate perfect surface
finishing for all prosthetic implant
documented, validated work protocol.
According to this protocol we machine
the basal region of the abutment with
special diamonded rubber polishers
(Serius Ceramics, Frankfurt/Main) and
so obtain a surface of between 2 to 4
microns of residual roughness, the proven
standard for optimal tissue accumulation
(Fig. 6).
Surface cleanliness
Fig. 7: The three images in the top row show contaminated components. The bottom three images show the
same surface after applying the validated cleaning process presented here.
It has been proven that contamination can
occur on implant abutments – regardless
of being customized or pre-assembled
– which leads to questions regarding a
long-term stable outcome (Fig. 7). The
following applies as a matter of principle:
customized abutments are medical devices
which are classified as being semi-critical
(Robert-Koch-Institute, RKI). In other
words, professional cleaning must be
logo 39 • the CAMLOG Partner Magazine • November 2016
performed. Evaporating is not sufficient,
and could, in fact, be counterproductive
(Fig. 8). This requires rethinking and
readjusting the dental work processes.
The third part of the article (logo 40)
will present a validated 3-step cleaning
protocol which leads to a clean and
perfectly hygienic abutment surface [2].
Abutments are medical devices
We should be aware that implant
abutments are medical devices which
have to meet certain criteria. Dental
technicians in particular, are faced
with a new range of tasks which they
should take on responsibly. It should be
determined in advance between the team
partners dentist and dental technician,
who is responsible for which step, and
how documentation is to be performed.
according to RKI guidelines bring with it?
These are all new work steps for dental
technicians which need to be incorporated
into a state-of-the-art laboratory concept.
This information is summarized by the
authors on a video which can be viewed
on the Sirius Ceramics YouTube channel.
The intention, status quo and the
validated procedure are presented in an
interesting and understandable manner.
manufacturing and the second article
the surface quality of implant abutments,
the third part will discuss the following
questions: which tasks are assigned to
the dental technician in the finishing of
pre-assembled or customized implant
abutments? Which formula ("cooking
recipe") leads to the desired goal? Which
steps does a clean abutment surface
Scan QR code
and view video
[1] Gehrke P, Kaiser W, Fischer C. Comparative analysis of
surface topography of custom of CAD/CAM zircona abutments by means of optical profilometry. In progress, 2015
[2] Gehrke P, Tabellion A, Fischer C. Microscopical & chemical
surface characterization of CAD/CAM zircona abutments
after different cleaning procedures. A qualitative analysis.
J Adv Prosthodont. 2015, Apr;7(2):151-9
Fig. 8: Simple evaporating of the CAD/CAM abutment is common practice, however, this does not comply with
the hygiene requirements for a semi-critical medical device. A clean result according to the RKI guidelines is not
[3] Sing T, Gehrke P, Fischer C, Geis-Gerstorfer J. Marginale
Adaptation und Klebefugengröße von zweiteiligen CAD/
CAM Zirkon-Implantataufbauten. Publication in progress,
Contact details
Contact details
Dental practice Prof. Dr. Dhom & Colleagues
Bismarckstr. 27 and
Berliner Platz 1
67059 Ludwigshafen
Telephone: 0621 68124444
Sirius Ceramics | Carsten Fischer
Lyoner Straße 44-48
D-60528 Frankfurt
Telephone: 069 66366910
Dr. med. dent. Peter Uwe Gehrke
Carsten Fischer
1991 licence to practice dentistry following dentistry studies at
the Free University Berlin. 1992 graduated to Dr. med. dent. After
receiving a scholarship from Schering AG, Pharmaceutical Industries,
Dr. Gehrke set up a private dental practice. Focus: prosthetics and
implant dentistry. After positions as Marketing Manager and Senior
Manager Medical Marketing in the implant industry, Dr. Gehrke is
now a partner for implant prosthetics at the oral surgery practice
Prof. Dr. Dhom. His focus is on implant dentistry and esthetic
dentistry and he is a part-time lecturer at Steinbeis University, Berlin,
for the Master of Science course in oral implantology and
periodontal therapy.
Self-employed as dental technician with his own business since
1996, and active as international speaker since 1994. Publications
in numerous countries (Brazil, Argentina, Japan, Australia, Europe).
2012-2015 part-time assistant at the Goethe University Frankfurt.
Carsten Fischer is a member of advisory boards and has acted as
advisor in the dental industry for many years. He focuses on
CAD/ CAM technologies, the ceramic double crown, customized
abutments and full ceramic materials. In 2013, his contribution was
honored as best lecture by the Working Group Dental Technologies,
ADT. Carsten Fischer is lecturer at the Steinbeis University, Berlin, and
speaker for various organizations (DGI) and Vice President of the EADT.
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