Zirconia Removable Telescopic Dentures
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Transcript of Zirconia Removable Telescopic Dentures
Zirconia Removable Telescopic DenturesRetained on Teeth or Implants forMaxilla Rehabilitation. Three-YearObservation of Three CasesGregory-George Zafiropoulos, DDS, Dr Dent, Dr Habil1*Jochen Rebbe, DT2
Ulrich Thielen, MDT2
Giorgio Deli, DDS, MD3
Christian Beaumont, DDS, Dr Med Dent2
Oliver Hoffmann, DDS, MSc, Dr Med Dent4
This report addresses maxillary restoration with removable telescopic crown-retained palatal
free dentures. One patient with 7 natural teeth (PERIO), a second patient with 6 dental
implants (IMPL), and a third patient with 2 natural teeth and 4 dental implants (IMPL-PERIO)
were treated. Zirconia copings for natural teeth and individual zirconia implant abutments
were fabricated in CAD/CAM and used as primary crowns. Electroformed gold copings were
used as secondary telescopes. All maxilla supraconstructions were fabricated with zirconia
and CAD/CAM. Patients were monitored during a 3-year period; all teeth and implants
survived, and no biological or mechanical complications occurred. The peri-implant and
periodontal conditions were healthy. While recognizing the limitations of this report, results
showed that fabricating removable zirconia structures by means of CAD/CAM can yield
highly functional and esthetic results. Galvanoforming technology is the preferable means of
fabricating secondary crowns. The combination of these techniques and materials results in a
prosthetic reconstruction of high quality, good fit, and biocompatibility. Long-term studies
of large populations are necessary to investigate the clinical properties of the material
utilized in this type of construction.
Key Words: dental implants, zirconia, telescopic crowns, removable dentures, implantabutments, electroformed crowns
INTRODUCTION
Anumber of recent studies rec-
ommend the use of removable
prostheses with telescopic at-
tachments fastened to natural
teeth and/or implants for pros-
thetic restoration.1–4 This restoration tech-
1 Department of Operative Dentistry and Periodontol-ogy, University of Mainz, Germany, and Blaues HausDental Center, Duesseldorf, Germany.2 Herrmann Dental Studio, Duesseldorf, Germany.3 Division of Periodontology, Catholic University ofSacro Cuore, Rome, Italy.4 Department of Periodontics, School of Dentistry,Loma Linda University, Calif.* Corresponding author, e-mail: [email protected]: 10.1563/AAID-JOI-D-09-00065
CLINICAL
Journal of Oral Implantology 455
nique is preferred in Central Europe for
partially edentulous and periodontologically
injured dentition. It has existed as a broadly
accepted and scientifically recognized ap-
proach within dentistry and predates the
establishment of oral implantology.5
In a current publication, our team also
discusses the advantages of telescope-borne
structures.6 Briefly, these advantages are: (1)
the distribution of force on the abutment; (2)
the provision of a foundation for effective
oral hygiene, and maintenance of periodon-
tal health; (3) the arrangement of teeth in
the desired position; (4) circumvention of
several augmentative measures in the soft
and hard tissues for esthetic reasons; (5)
achievement of favorable esthetics, even
with there is substantial recession of the
periodontal tissue or severe atrophy of the
jaw; (6) creation of a gum-free structure in
the maxilla; (7) longevity of the structure (eg,
veneers can be reapplied at any time, and
the structure remains in place even if one of
the abutment teeth or implants is lost); and (8)
avoidance of augmentative measures if gingi-
val and/or peri-implant recessions arise before
the construction is fabricated or while it is
being worn since recessions can be covered by
the lip shield.
The disadvantages of this type of con-
struction are: (1) high costs and technical
requirements; (2) the need for the dental
technician to master the individual steps for
creating such constructions; and (3) any
psychological burden experienced by the
patient provided with a removable construc-
tion.
Today, patients with periodontally re-
duced dentition and partially or fully eden-
tulous patients who are to be provided with
implants have become sensitized to esthetic
appearance in addition to the maintenance
of oral health. The introduction of zirconium
oxide (zirconia) as a biocompatible material
in restorative dentistry, the light weight of
the structures made with this material, the
development of new ceramics and compos-
ites for veneers, and the ongoing develop-
ment of CAD/CAM technology were the
factors that led us to manufacture tele-
scope-borne zirconia constructions.
MATERIALS AND METHODS
Patients
Three nonsmoking patients (1 female and 2
male) were selected for this retrospective
study. In 2005, all 3 patients presented for
treatment of advanced chronic periodonti-
tis7 in the office of one of the authors (G.G.Z.,
Duesseldorf, Germany). After multiple extrac-
tions over the previous 2 years, the first
patient (PERIO, female, 58 years old) had 7
natural maxillary teeth that were retained by
periodontal treatment. This patient rejected
the placement of an implant.
The maxillary teeth of the second patient
(IMPL, male, 65 years old) had been extract-
ed 4 years earlier, with the exception of teeth
number 2 and 15. These 2 teeth possessed
class II mobility but no defect in the region
of the furcation. They were integrated into
the existing restoration (telescopic-crown
overdenture). This patient requested an
implant-supported restoration of the maxilla.
The third patient (IMPL-PERIO, male,
60 years old) presented after multiple
extractions of maxillary teeth due to ad-
vanced periodontal disease. Teeth number 6
and 11 were present, with class II mobility.
The patient requested a palate-free, implant-
supported restoration of the maxilla and
periodontal treatment of the remaining
dentition.
All existing mandibular teeth of the 3
patients were preserved, and a partial
removable denture was not necessary for
mandible restoration in any of the patients.
Initial treatment
The full-mouth initial periodontal treatment
involved oral hygiene instructions, supragin-
Zirconia Telescopic Dentures for Maxilla Rehabilitation
456 Vol. XXXVI/No. Six/2010
gival tooth cleaning and polishing, and
subgingival scaling and root planing.
Surgical and implant treatment
In all 3 cases, subgingival scaling and root
planing was followed by access flap surgery.8
Six cylindrical screw-type implants (RN,
length 10 mm, 04.1 mm, SLA, Straumann,
Waldenburg, Switzerland) were placed in
the maxilla of the IMPL patient and 4
cylindrical screw-type implants (Straumann)
were placed in the maxilla of the IMPL-PERIO
patient, using a 1-stage surgical approach.
Following full-thickness flap elevation, oste-
otomy preparation was performed at 875
rpm, and implants were manually placed
at a torque of 35 Ncm (046.119/046.049
Straumann) in positions number 4, 5, 6, 11,
12, and 13 and in positions number 4, 5, 12,
and 13 (IMPL and IMPL-PERIO patients,
respectively).
Postoperative care
Both IMPL and IMPL-PERIO patients were
prescribed a systemic antibiotic (clindamycin,
Ratiopharm, Ulm-Donautal, Germany; 600 mg/d)
to be taken once a day for 6 days and the
oral analgesic diclofenac (Voltaren, Novartis
Pharma, Nuremberg, Germany; 100 mg/d for
4 days), starting 1 day prior to surgery and
implant placement. All 3 patients were
instructed to rinse twice daily with 0.1%
chlorhexidine (Chlorhexamed Fluid, Glaxo-
SmithKline, Buehl, Germany) for 3 weeks,
also starting 1 day before periodontal sur-
gery and implant placement.
Sutures were removed 8 days postoper-
atively. Follow-up appointments were sched-
uled twice a month during the first 2 months
after surgery, and once a month thereafter
until loading.
Temporaries
The IMPL patient was provided with a
provisional full denture for the maxilla. Teeth
number 2 and 15, which were given
telescopic crowns, were preserved to pro-
vide the denture with greater retention. The
PERIO and IMPL-PERIO patients were given
temporary removable partial prostheses.
Rehabilitation
Four months after implant placement (IMPL
and IMPL-PERIO patients) and 3 months after
periodontal treatment (PERIO patient), max-
illae were restored with telescopic crown-
retained palate-free removable dentures.
Impressions were taken with individual
acrylic trays (the open-tray impression tech-
nique was used for implant cases) using a
polyether impression material (Impregum
Penta Soft, 3M ESPE, Seefeld, Germany).
Casts were mounted on a semi-adjustable
articulator (SAM 2P, SAM Praezisionstechnik,
Gauting, Germany), using the face-bow
technique and check-bite registration.
A wax-up was created and used as an
orientation tool for the patient and surgeon
as well as for further planning of rehabilita-
tion. After the esthetic and functional try-in
with the wax-up, a matrix of C-silicone
(Zetalabor, Zhermack SpA, Badia Polesine,
Italy) was manufactured. The direction of
insertion and planned tooth position were
determined by this silicone key (Figure 1A).
In addition, it can be used to create a mock-
up.
Primary telescopic crowns
Implants
Customizable abutments were used (RN
synOcta 048.642, Straumann) to fabricate
the individual zirconia implant abutments.
These abutments consist of a prefabricated
cast-on base and a residue-free burn-out
plastic channel (Figure 1a). The plastic chan-
nels of the 6 abutments were patterned with
resin (Pattern Resin, GC Dental Products
Corp, Leuven, Belgium) (Figure 1b). The
patterns were scanned and milled in a
CAD/CAM (M4820, I-MES, Eiterfeld, Ger-
many). After scanning, the zirconia implant
Zafiropoulos et al
Journal of Oral Implantology 457
abutments were fixed on the abutment cast-
on base using a self-curing compomer
cement (AGC Cem, Wieland Dental, Pforz-
heim, Germany) (Figure 1c). Subsequently,
the zirconia implant abutments were ground,
polished and sintered, and served as primary
telescopes with a minimum thickness of
0.6 mm (Figure 1d through f).
Teeth
After the models were created, the tooth
abutments were scanned using construction
software (ZENO CAD, in CAD/CAM, Wieland
Dental) and a scanner (Dental Designer,
3shape, Copenhagen, Denmark), and the
primary telescopes were fabricated and
milled as zirconia copings (ZENO Discs,
Wieland Dental) (Figure 2a and b). An
insertion key of resin (Pattern Resin, GC
Dental Products Corp) and a metal wire
0.3 mm in diameter were manufactured and
used for an oral try-in of the primary
telescope on the abutment to determine
precision of fit and direction of insertion
(Figure 2c).
Subsequently, a new impression was
made over the primary telescope and
insertion key using a polyether impression
material (Impregum Penta Soft, 3M ESPE,
Seefeld, Germany). This was used to fabricate
a new working model of cast plaster
(Figure 2d and e).
Secondary Telescopic Crowns
As secondary telescopes, electroformed pure
gold copings with a thickness of 0.25 mm were
fabricated (AGC Galvanogold, Au . 99.9%,
Wieland Dental) (Figure 3a through c).9,10
Supraconstructions
The superstructure was created by using
construction software (ZENO CAD in CAD/
CAM, Wieland Dental) and a scanner (Dental
Designer, 3shape, Copenhagen, Denmark)
(Figure 3d). Subsequently, a milling program
(ZENO CAM, Wieland Dental) was used to
create a plastic mock-up (ZENO-PMMA, Wie-
land Dental) on a milling machine (I-MES,
Eiterfeld, Germany). The mock-up was then
tried in to check occlusion and the overall
shape of the construction (Figure 3e). After
the try-in and necessary corrections, the
altered mock-up was scanned again. The
zirconia framework (ZENO Discs, Wieland
FIGURE 1. (a) Creation of implant abutments using C-silicon matrix as orientation. (b) Wax-up of animplant abutment before scanning. (c) Zirconia implant abutments were fixed on the synOcta titanparts. (d) Zirconia implant abutment was ground, polished, and sintered. (e) Finished zirconia implantabutment. (f) Fit-in of the zirconia implant abutments. IMPL patient: region number 2 and 15 naturalteeth with primary telescopes of the ‘‘old’’ restoration.
Zirconia Telescopic Dentures for Maxilla Rehabilitation
458 Vol. XXXVI/No. Six/2010
Dental) was then milled using a CAD/CAM
system (M4820, I-MES, Eiterfeld, Germany)
and sintered in a sintering furnace (ZENO
Fire, Wieland Dental) for 14 hours at 1500uC(Figure 4a). To veneer the implant-retained
supraconstruction, a high-fusing microce-
ramic (Vintage ZR, Shofu Dental, Ratingen,
Germany) was used. To veneer the natural
tooth-retained supraconstruction, a lightly
cured indirect ceramic polymer (Ceramage,
Shofu Dental) and a bonding system (Bond I
and II, Shofu Dental) were used (Figure 4B
through E). The zirconia superstructure
possessed a wall thickness of 0.6 mm,
occlusal distance of 1.5 mm and 3 3 3 mm
proximal connecting elements.
FIGURE 2. (a) Zirconia copings were CAD/CAM created. (b) Finished zirconia coping. (c and d) Fit-in of thezirconia copings. (e) New working model fabricated after fit-in of the copings.
FIGURE 3. (a) Fabrication of electroformed gold copings. (b) IMPL patient, zirconia implant abutments asprimary telescopes with secondary gold copings as secondary telescopes; natural teeth number 2 and15 with primary telescopes from the old restoration. (c) Supraconstruction was created in CAD/CAM.(d) IMPL patient mock-up. (e) PERIO patient mock-up.
Zafiropoulos et al
Journal of Oral Implantology 459
After veneering, the gold copings were
fixed in the supraconstruction using a self-
curing copolymer cement (AGC Cem, Wie-
land Dental) (Figure 4f ). After fitting the
denture, the jaw relation was rerecorded
using a central tracing device and a face-
bow, remounted to a semi-adjustable artic-
ulator (SAM 2P, SAM Praezisionstechnik).
Final adjustments to the occlusion were
made (Figure 5a through d).
The zirconia implant abutments were
manually placed at a torque of 35 Ncm.
The screw opening of the abutment was
filled with a single-component light-cured
resin (Fermit, Ivoclar Vivadent, Schaan, Liech-
tenstein) (Figure 5e).
FIGURE 4. (a) CAD/CAM fabricated zirconia supraconstruction. (b and c) Finished/veneered supra-construction for PERIO patient. (d and e) Finished/veneered supraconstruction for IMPL patient.(f) Gold copings fixed in the supraconstruction.
FIGURE 5. (a and b) Attachment system with natural tooth abutments 1: zirconia copings, 2: goldcopings, and 3: zirconia supraconstruction. (c and d) Attachment system with implant abutments 1:zirconia implant abutments, 2: gold copings, and 3: zirconia supraconstruction. (e) The screw openingof the zirconia implant abutment was filled with a resin.
Zirconia Telescopic Dentures for Maxilla Rehabilitation
460 Vol. XXXVI/No. Six/2010
In all 3 cases, the superstructures were
extended only up to teeth number 3 and 14
with cantilevers. The cantilevers at teeth
number 3 and 14 were supported by the
veneer material on the mucosa (Figures 6
through 8).
In the IMPL patient, teeth number 2 and
15 manifested improved mobility (class I) and
inflammation-free periodontal conditions at
the time of the prosthetic restoration. For this
reason, both teeth were retained according to
the patient’s wishes. Two zirconia crowns
(Panavia, Kuraray Europe, Frankfurt/M, and
Germany) were fabricated and adhesively
inserted on the existing, old primary telescopic
crowns number 2 and 15 which were intact and
free of caries (Figure 6a through f ).
Maintenance
Follow-up examinations were performed at
the time of loading, and were considered the
baseline examinations (BSL). At the BSL, and at
the 1-, 2- and 3-year examinations after
loading, the implants and/or natural teeth
were examined at 4 sites per tooth. These
examinations measured bleeding on probing
(BOP) and plaque index11; in addition, a
periodontal probe (UNC 15, Hu-Friedy, Lei-
men, Germany) was used to estimate probing
attachment level (PAL) for implants and
clinical attachment level (CAL) for natural
teeth. PAL was defined as the distance in
millimeters between the deepest point of the
peri-implant pocket and the margin of the
zirconia implant abutment. CAL was defined
as the distance between the deepest point of
the periodontal pocket and the margin of the
zirconia primary crowns. All measurements
were rounded up to the nearest millimeter.
RESULTS
Three patients were treated (IMPL, PERIO,
and IMPL-PERIO). Ten dental implants were
FIGURE 6. IMPL patient. (a–c) Clinical view right – front – left. (d) Orthopantomograph. (e) Palatal view. (f )Anterior area close-up.
FIGURES 7 AND 8. FIGURE 7. PERIO patient. (a–c) Clinical view right – front – left. (d) Orthopantomograph.FIGURE 8. IMPL-PERIO patient. (a) Orthopantomograph. (b and c) Clinical view.
Zafiropoulos et al
Journal of Oral Implantology 461
placed in the maxillae of 2 patients (IMPL
and IMPL-PERIO), and 9 maxillary natural
teeth in the maxillae of 2 patients (PERIO and
IMPL-PERIO) were used as retainers for the
restorations. The maxillae of all 3 patients
were restored with removable telescopic
dentures. Implant abutments, copings for
natural tooth abutments, and superstruc-
tures were fabricated using CAD/CAM. In all
cases, electroformed gold copings were
fabricated as secondary telescopes.
The patients were observed over a period
of 3 years. None of the patients reported any
unusual pain or discomfort, abscess, swell-
ing, or allergic reactions during the course of
treatment. No implants or natural teeth were
lost during the observation period. Further-
more, no fractures were observed in the
zirconia abutments, the superstructures, or
the ceramic veneers (Figure 9).
The small sample size and limited num-
ber of measurements in this study rendered
it not amenable to statistical analysis. How-
ever, there were no observed changes in
BOP and plaque index measurements be-
tween the BSL and subsequent examina-
tions. The mean range of BOP values for the
maxillary natural teeth was 5% and that for
the implants was 2%–4%. Plaque index
scores ranged from 5%–8%. At the BSL, the
mean PAL was 1 mm. The PAL deteriorated
by 1 mm at the year 1 examination and a
further 0.5 mm at the year 3 examination.
The mean CAL at the BSL was 2.5 mm, and
the range was 3.5–4 mm between the year 1
and year 3 examinations.
DISCUSSION
In the present study, the maxillae of 3
patients were restored with removable,
telescopic crown-retained, palate-free den-
tures. All implants and natural teeth, prima-
ry telescopes, and supraconstructions re-
mained functional, and none of the patients
suffered complications thoughout the 3-
year observation period.
FIGURE 9. Three-year clinical view. (a) Zirconia copings. (b) Zirconia implant abutment.
Zirconia Telescopic Dentures for Maxilla Rehabilitation
462 Vol. XXXVI/No. Six/2010
The use of ceramics in dentistry and
dental technology has increased in recent
years. Among other materials, zirconia has
been used to manufacture frameworks due
to its good mechanical and biocompatible
properties.12–15 Importantly, during the en-
tire observation period of the present study,
no biological or mechanical complications
were observed, and all reconstructions re-
mained functional. This observation is in
agreement with the few studies that have
examined removable dentures retained on
teeth or implants using zirconia for the
fabrication of copings and/or implant abut-
ments.12,16–20 The present study differs from
other published studies in that the supra-
structures were also fabricated from zirconia
and not from metal. The periodontal and
peri-implant findings were overall very pos-
itive.
Clinical studies of zirconia implant abut-
ments and copings have shown them to
have favorable stability and to exhibit a
survival outcome similar to that of gold or
titanium structures.17,18,21 Similar to prior
studies, we found the bone level around the
implants and/or natural tooth abutments to
be stable and the soft tissue to be
healthy.12,16,17,19–21 Recent studies have re-
ported that zirconia shows a lower bacterial
colonization potential than titanium in
vivo.22–25 It has been further asserted that
this material can help stabilize soft tissue
against inflammation and contribute to the
stability of the crestal bone level around the
implants.17,23,25,26
In the present study, low plaque accu-
mulation and low BOP were also observed.
The probing depth of the periodontal or
peri-implant areas was stable and no gingi-
val recessions were seen. Gingival recessions
may cause esthetic complications that must
be surgically managed, particularly when
they occur in the anterior region. These
may lead to patient dissatisfaction and
caries. Although in the cases presented here
no such problem was observed, the occur-
rence of gingival recessions in the future
cannot be ruled out. In such a case, too, the
removable telescopic crown-retained con-
struction offers the great advantage that the
lip shield covers these areas, and plastic
periodontal surgery for the purpose of
correcting the soft tissue contours is not
necessary.
A number of studies have reported on the
fabrication of zirconia copings for providing
retention of a telescopic crown-retained over-
denture.12,16,20 Other studies report positive
mechanical properties of zirconia copings in
fixed restorations.12,16,25,27,28 No fractures of
the zirconia copings were observed in the
present study. These copings proved to be a
successful alternative to classic gold copings,
especially when the patient’s esthetic de-
mands are high. However, the preparation
angle of the natural abutments, the thickness
of the zirconia, and the occlusal load must
be precisely factored in.29–31
The secondary telescopes were manufac-
tured by galvanoforming and electroform-
ing. This process yields a precisely-fitting
secondary coping that closely mates with
the primary telescope with a gap of 12–
30 mm. The gold electroformed coping saves
space and is made of high-quality material.
In order for its shape to remain stable, it
must be completely surrounded by the
superstructure framework and may not
merely be adhered to the veneer.9,10,16 The
fixation of the electroformed copings should
be done after the veneering of the supra-
construction is completed. The combination
of both materials, zirconia and electroform-
ing copings, used with the proper technol-
ogies, results in a prosthetic reconstruction
of high quality, good fit. and biocompatibil-
ity.
Developments in CAD/CAM technology
have resulted in discernible improvement in
these methodologies.32–34 New technologies
must take into account the specific require-
Zafiropoulos et al
Journal of Oral Implantology 463
ments of dental technology and dentistry,
and a great deal of time is required before
they become routine. In the present study,
all parts of the telescope-borne removable
reconstructions were fabricated using CAD/
CAM. Over the 3-year observation period, no
complications were noted from the individ-
ual parts made using this technology.
Nevertheless, the lack of long-term results
must be borne in mind. We do not yet know
whether the mechanical and prosthetic-
specific properties of the material will remain
satisfactory over the long term, and whether
they will prove to be as valuable as the
established classic methods and materials of
dental technology. Randomized long-term
studies with a large number of test subjects
are required. Even if the overall number of
restorations fabricated with CAD/CAM, espe-
cially all-ceramic frameworks made of mate-
rials such as zirconia, remain comparatively
fewer than conventionally-fabricated frame-
works, this technology has great potential
for economical and biocompatible restora-
tions using innovative materials that are
esthetically and functionally superior.
This report presents the option of restor-
ing the maxilla with classic techniques from
oral implantology as well as prosthetic
dentistry using modern dental materials.
The esthetic and functional results over the
3-year observation period were very positive.
Long-term results from large, preferably
randomized studies would be desirable and
necessary to establish greater clarity regard-
ing the long-term potential changes in the
properties of zirconia. It would, of course, be
possible to reconstruct the maxillae of the
patients discussed by hard and soft tissue
augmentation in order to allow the fabrica-
tion of a fixed prosthetic restoration. In such
cases, one is confronted with the dilemma of
whether all the possibilities of modern
surgery should be exhausted, or if it would
be more desirable to pursue ‘‘the path of
least resistance’’ and combine classic and
modern methods. If the latter route is taken,
we as surgeons or periodontists should give
more weight to the option of restorative
dentistry.
ABBREVIATIONS
BOP: bleeding on probing
BSL: baseline examinations
CAL: clinical attachment level
PAL: probing attachment level
NOTES
The authors report no conflicts of interest
related to this study. No financial or material
support was provided by any company to the
authors or the patients involved in this study.
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