1. estudio clinico de 10 años de inlays direcra e indirecto de composite y ceramica

VOLUME 37 • NUMBER 2 • FEBRUARY 2006 139
QUINTESSENCE INTERNATIONAL
Esthetic awareness by patients has
increased the interest in tooth-colored
restorations, even in the posterior area.
Though amalgam restorations still show a
more favorable cost-benefit behavior com-
pared to gold with a median age of failed
restorations of 15 years,1
these restorations
are not accepted by many patients because
of the inferior esthetics. In the stress-bearing
posterior region, composite restorations have
failed mainly because of marginal or bulk
fractures due to fatigue2–4
or secondary
caries.3,4
To solve these problems, great inter-
est has been taken in various inlay tech-
niques. These include composite as well as
ceramic inlays with physical properties
almost similar to enamel.5,6 A number of
short-term studies have been done to evalu-
ate the durability or performance of various
A prospective clinical study of indirect and direct
composite and ceramic inlays: Ten-year results
Marianne Thordrup, DDS, PhD1
/Flemming Isidor, DDS, PhD, Dr Odont2
/
Preben Hörsted-Bindslev, DDS3
Objective: The aim of this investigation was to evaluate the clinical performance of 4 types of
tooth-colored inlays. Method and materials: Fifteen direct ceramic inlays (Cerec Cos 2.0), 15
direct composite inlays (Brilliant DI, Coltène), 14 indirect ceramic inlays (Vita Dur N), and 14 indi-
rect composite inlays (Estilux, Kulzer) were placed in 37 patients, according to manufacturer
instructions. The inlays were evaluated 1 week (baseline), 6 months, and 1, 3, 4, 5, and 10 years
after cementation (modified California Dental Association Quality Evaluation System). The ratings
were compared using the chi-square test. For comparing the survival rates among the 4 types of
inlays, a life-table analysis was done, followed by a log-rank test. Results: Three Vita Dur N
inlays were replaced after 1, 4, and 8.5 years; 3 Cerec inlays were replaced after 4.5, 8.5, and
9.5 years; and 3 Brilliant DI inlays needed replacement after 1, 5, and 6.5 years, all because of
secondary caries or fractures. Three inlays (Estilux) were replaced because of persisting hyper-
sensitivity or pulpal damage. Six inlays (3 Vita Dur N, 1 Estilux, and 2 Brilliant DI) were repaired
for minor fractures. During the observation period, the surface texture of Vita Dur N inlays
became significantly rougher. About 80% of the inlays, including repaired inlays, were in function
after 10 years. Conclusion: After 10 years of observation, survival of the 4 types of tooth-colored
inlays was similar and considered clinically acceptable. The survival rates were within the range
of survival for direct composite restorations. (Quintessence Int 2006;37:139–144)
Key words: ceramic, inlay, marginal adaptation, morphology, resin composite,
surface texture, survival rate
1
Research Associate, Department of Dental Pathology,
Operative Dentistry and Endodontics, School of Dentistry,
Faculty of Health Sciences, University of Aarhus, Denmark.
2
Professor, Department of Prosthetic Dentistry, School of
Dentistry, Faculty of Health Sciences, University of Aarhus,
Denmark.
3
Associate Professor, Department of Dental Pathology,
Operative Dentistry and Endodontics, School of Dentistry,
Faculty of Health Sciences, University of Aarhus, Denmark.
Reprint requests: Marianne Thordrup, Department of
Dental Pathology, Operative Dentistry and Endodontics,
Faculty of Health Sciences, School of Dentistry, University of
Aarhus, Vennelyst Boulevard 9, DK-8000 Aarhus C, Denmark.
Fax: +45 8620 2202. E-mail: ph-b@odont.au.dk.
COPYRIGHT © 2005 BY QUINTESSENCE PUBLISHING CO, INC.
PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY.
NO PART OF THIS ARTICLE MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM
WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.

140 VOLUME 37 • NUMBER 2 • FEBRUARY 2006
Thordrup et al
tooth-colored inlays.7–15 Results of some con-
trolled clinical studies considering long-term
observation periods are available.16–22 The
clinical results are not always encouraging.
Some studies show failure rates from 0% to
3%,18,23 whereas other studies have reported
failure rates of 16% to 25% after 3 to 6 years
of observation.14,16 The procedures involved
in producing inlays are more time consum-
ing and costly compared to the procedures
for making direct restorations. However, a
review article from 2004 reports a lower
annual failure rate for inlay techniques than
for direct restoration techniques.24
The aim of the present long-term clinical
trial was to evaluate the durability and per-
formance of 4 different kinds of ceramic and
composite inlays. The primary outcome
measure was defined as inlay survival, while
morphology, color match, surface texture,
and marginal adaptation were secondary
outcome measures. It was hypothesized that
minor flaws in these categories do not seri-
ously affect the function or survival of inlays.
METHOD AND
MATERIALS
Thirty-seven patients (7 men and 30 women
from 23 to 69 years of age) with 58 posterior
restorations were selected for this study.
Patients with clenching, bruxism, severe mal-
occlusion, periodontitis, pronounced gingival
inflammation, poor oral hygiene, or a high
caries progression, as well as patients wear-
ing partial dentures, were excluded. Inclusion
criteria were 1 to 4 posterior teeth with large
mesio-occlusodistal (MOD) restorations sched-
uled for replacement. The optimal design of
4 different inlays in each patient was aban-
doned since the demand of 4 large MOD
restorations in each patient proved to be unre-
alistic. The inlay materials for each restoration
were then assigned randomly.
The 4 different inlay materials used were
direct ceramic (Cerec, Siemens), indirect
ceramic (Vita Dur N, Vita Zahnfabrik), direct
composite (Brilliant DI, Coltène), and indirect
composite inlays (Estilux, Kulzer). In 17
patients, 2 teeth were included in the study,
allowing the following combinations for inlay
treatment: direct composite/indirect com-
posite (5 patients); direct ceramic/indirect
ceramic (6 patients); direct composite/
direct ceramic (3 patients); and indirect com-
posite/indirect ceramic (3 patients). The
remaining 20 patients received 1 inlay each.
Consequently, a total of 15 direct ceramic, 14
laboratory (indirect) ceramic, 15 direct com-
posite, and 14 laboratory (indirect) composite
inlays were made.
All inlays were prepared, inserted, cement-
ed, and evaluated by the same operator (MT).
No blinding of inlays and patients was possi-
ble since each type of inlay material was eas-
ily recognized. For the indirect inlays, a sili-
cone impression (President, Coltène) was
taken. The indirect ceramic inlays (Vita Dur N)
were fabricated on fire-resistant dies of Hi-
Ceram (Vita) refractive materials, while the
indirect composite inlays (Estilux) were made
on the original stone dies followed by light
and heat curing.
Direct composite inlays (Brilliant DI) were
made according to the manufacturer's
instructions. Each inlay was made using the
bulk technique, preliminary contouring of the
occlusal morphology, and light curing for 3
minutes (Heliomat type H2, Vivadent).
Afterward, the inlay was removed and heat
cured before cementation. A final contouring
of the occlusal surface was always necessary
after cementation.
The direct (CAD/CAM) ceramic inlays
(Cerec Cos 2.0) were based on an “optic
impression” of the cavity taken with a light-
transmitting video camera and made accord-
ing to the manufacturer’s instructions.25
The
occlusal morphology had to be contoured by
the operator.
The cementation procedure was similar
for all groups. A transparent composite
molar matrix band (Hawes, Coltène) was
used for moisture control. Before cementa-
tion, the ceramic inlays were treated with
hydrofluoric acids and silica solutions
according to the manufacturer's instructions.
In all groups, the cavosurface enamel was
etched for 40 seconds using Ultra Etch 40%
phosphoric acid (Ultradents Products). The
exposed dentin was treated with a dentin-
bonding system (Gluma 2 and 3, Bayer

Thordrup et al
Dental) according to the manufacturer's
instructions. Light curing was performed
with the Heliomat Light Unit. (For details see
Thordrup et al.11) The inlays were polished
after 1 week with Cerec diamonds and rub-
ber points (Shofu). Following occlusal con-
touring and adjustment, the ceramic inlays
were polished with a diamond paste (Ultra
Diamond Polish, Ultra Dent).
At baseline and at the follow-up examina-
tions (6 months and 1, 3, 4, 5, and 10 years
after cementation), the inlays were evaluated
for marginal adaptation, morphology, color
match, surface texture, sensitivity and dis-
comfort, and proximal contact points using
the California Dental Association (CDA)
Quality Evaluation System.26 The second best
rating, S (acceptable), for marginal adaptation
was modified in this study. This rating was
given not only for “visible ditches” but also
for “probed roughness or irregularities” along
the inlay margin. In addition, bitewing
radiographs were taken to support the clinical
evaluation. For each parameter the most
severe score of the surface was recorded.
Concerning the proximal marginal adaptation
of the inlays, the most severe score of either
the mesial or the distal surface was chosen as
the proximal score.
Survival rates of the tooth-colored inlays
were expressed in 2 different terms: the total
number of inlays that were still in function
after 10 years (repaired or not repaired7) and
the inlays that functioned without any compli-
cation, excluding all inlays repaired during the
observation period.
Statistical analysis
A life-table analysis was developed and the
log-rank test was used for comparing the sur-
vival rates among the various types of inlays.
Afterward, the ratings between baseline
observations and follow-up examinations
were compared using the chi-square test. The
chi-square test was supplied with another sta-
tistical analysis (rank sum test). For both sta-
tistical tests P < .05 was chosen as the signif-
icance level.
Reproducibility of measurements
To evaluate the reproducibility of the CDA
index assessments, the observer performed
2 independent registrations on 11 inlays. The
intravariation of CDA index ratings showed
complete agreement (100%) for morphology,
surface texture, and color match for all
assessments. The intravariation of ratings for
marginal adaptation at proximal surfaces
showed 75% agreement.
RESULTS
After 10 years of observation, 6 inlays in 4
patients were lost to follow-up, as 2 patients
died and 2 patients dropped out just after
baseline registrations. The inlay combina-
tions were 1 Vita Dur N and 1 Estilux in 1
patient (deceased), 1 Estilux and 1 Brilliant DI
in another (dropout), 1 Estilux in 1 patient
(deceased), and 1 Brilliant DI in the last
patient (dropout).
Eleven inlays were replaced during the
observation period. The operator replaced 2
Vita Dur N inlays, 1 Estilux inlay, and 1
Brilliant DI inlay. The patients' own dentists
replaced 4 Cerec inlays, 1 Vita Dur N inlay, 1
Estilux inlay, and 2 Brilliant DI inlays.
Inlay replacement necessitated by frac-
tures was observed for the 3 Vita Dur N
inlays, 1 Cerec inlay, and 1 Brilliant DI inlay.
The Vita Dur N inlays fractured after 1, 4, and
8.5 years of service, the 1 Cerec inlay after
9.5 years, and the Brilliant DI inlay after 6.5
years. Secondary caries was the reason for
replacement of 2 Cerec inlays after 4.5 and
8.5 years, as well as for 2 Brilliant DI inlays
after 1 and 5 years. Replacement of the 2
Estilux inlays was necessitated by pulpal
reactions. One inlay was replaced after 2
years because of persisting hypersensitivity.
The other inlay was removed after 8 years
and the inlay tooth endodontically treated.
Of the 41 inlays available for examination
after 10 years of function, 30 were examined
by the operator (9 Cerec inlays, 7 Vita Dur N
inlays, 8 Estilux inlays, and 6 Brilliant DI
inlays) and 11 inlays were examined by the
patients' own dentist. In these cases, the den-
tist gave a description of the inlay status and
function supplied with bitewing radiographs
(3 Cerec inlays, 3 Vita Dur N inlays, 1 Estilux
inlay, and 4 Brilliant DI inlays).

Thordrup et al
For example, repair instead of replace-
ment was indicated for inlays showing minor
fractures involving 1 proximal inlay surface.
Corpus fractures always led to inlay replace-
ment, and so did secondary caries. Repair
was performed by preparing a cavity involv-
ing the affected inlay surface and inserting a
resin composite restoration material by adhe-
sive technique.
A total of 6 inlays were repaired but were
actually still in function at the 10-year control.
Five inlays were repaired by the operator
(2 Vita Dur N inlays, 1 Estilux inlay, and 2
Brilliant DI inlays) and 1 inlay (Vita Dur N) was
repaired by the patient's own dentist. No
Cerec inlays were repaired during the obser-
vation period.
The survival rate after 10 years for all inlays
in function (with or without repair) was 80%
for the Cerec inlays, 77.4% for the Vita Dur N
inlays, 75.5% for the Estilux inlays, and 80%
for the Brilliant DI inlays (Fig 1). The survival
rate for inlays without repair was 80% for the
Cerec inlays, 61.9% for the Vita Dur N inlays,
50.8% for the Estilux inlays, and 66.7% for the
Brilliant DI inlays (Fig 2).
When the survival rates for the 4 inlay
groups were compared with a log-rank test,
no statistically significant differences were
found for either of the 2 definitions of survival.
The marginal adaptation of the inlays was
previously reported at the 5-year control.20
No
changes from these results were revealed at
the 10-year control. From baseline to 10
years, no significant differences were found
in morphology for any type of inlay. No signif-
icant differences in morphology were found
when comparing the 4 different inlay groups.
At baseline, the Vita Dur N inlays showed
the best color match, but after 10 years, all
types of inlays showed a decreased frequen-
cy of perfect ratings; the Vita Dur N inlays
were no longer superior to Cerec, Estilux, and
Brilliant DI inlays.
After 10 years of observation, the surface
texture for Vita Dur N inlays became signifi-
cantly rougher (P < .01), and increasing
roughness was found for Brilliant DI inlays.
No significant differences in surface texture
were found among the 4 groups of inlays.
All patients were satisfied with the esthetic
result of the inlay treatment, and, except for
the replaced inlays, no serious complaints
were recorded for any type of inlay.
DISCUSSION
The survival rates in this study were 76% to
80% for all inlays in function with or without
repair. When all repaired inlays are excluded,
Fig 1 Survival curve of life-table analysis of inlays
that were clinically in function during the observation
period.
Fig 2 Survival curve of life-table analysis of inlays
that did not show any complications (repair) during
the observation period.

Thordrup et al
the survival rate decreases from 80% to 51%.
Other long-term studies show similar survival
probabilities and failure rates. Hayashi et al18
found 18% failures for fired ceramic inlays.
Otto and de Nisco27 recorded 8% failed
Cerec inlays and a survival probability of
90.4% after 10 years. After 11 years, Van
Dijken19 reported 17% failed composite
inlays, and Reiss and Walther28 found a sur-
vival probability of 90% for Cerec inlays after
10 years, decreasing to 84.9% after 11 years.
Malament and Socransky29 showed a sur-
vival probability of Dicor inlays at 92% after
11.3 years.
Because of the marginal imperfection of
the Cerec inlays30 observed after 1 year,11 it
was expected that the Cerec inlays would
show clinical complications in the long term.
The rather large marginal gaps of the Cerec
inlays might have led to unacceptable, pro-
gressive wear and degradation of the resin
composite luting cement. This did not hap-
pen in the present study. Furthermore, the
imperfect internal fit30 that might have caused
an insufficient occlusal thickness of the
Cerec inlays resulted in only 1 inlay fracture.20
As described earlier,20 the initial smooth
surface texture of the Vita Dur N inlays and
the Brilliant DI inlays changed into localized
rough areas at the occlusal contacts. All
types of tooth-colored inlays show decreas-
ing esthetic appearance during long-term
observation. Surface wear and marginal
staining are examples that may change an
inlay with a perfect color match to a nonper-
fect match. Decreasing esthetics of ceramic
inlays have also been reported by Fuzzi and
Rapelli23 when extending the observation
time beyond 5 years.
The survival rates of posterior composite
restorations in controlled clinical studies
have been reported as 95% after 3 years,31
85% to 90 % after 5 years,32–34 77% after 8
years,33 72% after 11 years,19 74% after 10
years,35 and 40% to 50% after 10 years.36
Compared to these rates, the survival rates of
the present study are within the range of the
survival for direct composite restorations.
In the present study, the 10-year survival
rates of the various types of inlays were simi-
lar. The small number of inlays represents a
statistical problem, since large differences in
the outcome have to be recorded to give sta-
tistically significant differences. Therefore,
the conclusions must be drawn with caution,
but still the results of this study contribute to
the general knowledge of the long-term
behavior of various tooth-colored inlays. For
long-term clinical studies, the risk of patient
dropout represents a significant problem.
Dropout rates have been reported from 9%
to 55% of the total number of registered
restorations after 10 years.27,35–38 In this inves-
tigation, 52 of originally 58 inlays could be
accounted for after 10 years. In other words,
only 10% of the inlays were lost to follow-up
for registration of inlay survival.
About 80% of the tooth-colored inlays in
the present study were still in function after
10 years. This survival rate is similar to the
survival of direct composite restorations as
reported in the literature.
CONCLUSIONS
No significant differences were revealed
among the survival of the different types
of inlays. The main reasons for inlay failures
during the observation period were fractures
or secondary caries. Esthetic appearance
decreases for all types of inlays. Vita Dur N
and Brilliant DI became significantly rougher
during the observation period.
The 4 types of inlays are considered clini-
cally acceptable and demonstrate survival
rates similar to those reported for direct com-
posite restorations.
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1. estudio clinico de 10 años de inlays direcra e indirecto de composite y ceramica

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1. estudio clinico de 10 años de inlays direcra e indirecto de composite y ceramica