F. LI, W. LI: EFFECTS OF THREE-DIMENSIONAL-PRINTED ZIRCONIA ALL-CERAMIC CROWNS ...
149–154
EFFECTS OF THREE-DIMENSIONAL-PRINTED ZIRCONIA
ALL-CERAMIC CROWNS ON PERIODONTAL HEALTH AND
AESTHETICS OF PATIENTS RECEIVING ANTERIOR TOOTH
AESTHETIC RESTORATION
TRIDIMENZIONALNO TISKANJE CIRKONIJEVEGA OKSIDA NA
KERAMI^NE ZOBNE PREVLEKE IN NJEGOV VPLIV NA
ZDRAVJE OBZOBNIH TKIV TER PACIENTOVO ZOBNO
ESTETIKO PO PREDHODNI ESTETSKI OBNOVI ZOBOVJA
Fengxian Li
1
, Wei Li
2*
1
Renhe Hospital Affiliated to China Three Gorges University, Yichang 443000, Hubei Province, China
2
China Three Gorges University, Gezhouba Central Hospital of Sinopharm, Yichang 443000, Hubei Province, China
Prejem rokopisa – received: 2023-01-09; sprejem za objavo – accepted for publication: 2023-02-10
doi:10.17222/mit.2023.738
The aim of this study was to evaluate the effects of three-dimensional (3D)-printed zirconia all-ceramic crowns on the
periodontal tissues and aesthetics of patients receiving anterior tooth aesthetic restoration. A total of 85 patients with anterior
tooth defects treated from January 2018 to October 2019 were selected. We studied zirconia all-ceramic crowns made by com-
puter-aided design and computer-aided manufacturing (CAD/CAM) (control group) and 3D printing (observation group). The
short-term restoration effects, periodontal health indices, functional recovery, long-term clinical efficacy and aesthetic effects
were compared. The gingival marginal fitness of the observation group was better than that of the control group, but the control
group had better tooth color matching (P < 0.05). One year after the restoration, the bleeding index, probing depth, attachment
loss, gingival index and plaque index all declined in the two groups, particularly in the observation group. Both the masticatory
and language functions were improved in the two groups, especially in the observation group (P < 0.05). Both 3D-printed and
CAD/CAM zirconia all-ceramic crowns have better cosmetic restoration effects on the anterior teeth. However, 3D-printed zir-
conia all-ceramic crowns have better gingival marginal fitness, which can benefit the periodontal tissue recovery, relieve
gingival inflammation, and improve masticatory and language functions.
Keywords: three-dimensional-printed zirconia, all-ceramic crown, anterior-tooth aesthetic restoration, periodontal health, aes-
thetics
Namen {tudije je bil ovrednotenje vplivov popolnega tridimenzionalnega tiska cirkonijevega oksida na kerami~ne prevleke na
parodontalno tkivo in estetiko pacienta po predhodni zobozdravni{ki obnovi zob. Za {tudijo so izbrali 85 pacientov, katerim so
pred tem popravljali po{kodbe na zobeh med januarjem leta 2018 in oktobrom leta 2019. Izbrali so prevleke na osnovi
cirkonijevega oksida. Izdelali so jih s pomo~jo postopka ra~unalni{kega oblikovanja in izdelave (CAD/CAM; kontrolna skupina)
in postopka izdelave s pomo~jo tridimenzionalnega tiskanja (opazovana skupina). Med seboj so nato primerjali kratkotrajne
u~inke obeh vrst obnove, indekse parodontalnega zdravja ter funkcionalne popravke, dolgotrajno klini~no u~inkovitost in
estetiko. Marginalni fitnes oziroma zdravje dlesni opazovane skupine je bilo bolj{e od kontrolne skupine toda kontrolna skupina
je imela bolj{e ujemanje barve zob (P < 0,05). Eno leto po obnovi so se vrednostni kazalci pri obeh skupinah zmanj{ali (indeks
krvavenja, globina, izguba pritrditve, dlesenski indeks in indeks pritrditve), {e posebej je bilo to izrazito pri opazovani skupini.
Funkciji `ve~enja in govora sta se izbolj{ali pri obeh skupinah, {e posebej pri opazovani skupini (P < 0,05). Obe izvedbi
(tridimenzionalnotiskane in s CAD/CAM izdelane prevleke iz cirkonijevega oksida) sta imeli bolj{i kozmeti~ni vpliv na
popravljena zobovja. Dolgoro~na pa ima tridimenzionalni tiskan cirkonijev oksid ugodnej{i vpliv na zdravje dlesni, kar ima
prednost pri obnovi parodontalnega tkiva, zmanj{uje vnetja dlesni, izbolj{ana sta `ve~enje in govorna funkcija.
Klju~ne besede: tridimenzionalno natiskan cirkonijev oksid, kerami~ne zobne prevleke, predhodna estetska obnova zob, ,
parodontalno zdravje, estetika
1 INTRODUCTION
Anterior-tooth aesthetic restoration has attracted
widespread attention recently.
1
Porcelain-fused-to-metal
crowns were widely used restoration materials in the
early days, among them the commonly used gold alloy
porcelain crowns were typified by few contraindica-
tions.
2
However, their shape was not lifelike enough, the
tooth was not transparent, the marginal fitness was unsat-
isfactory, and gingivitis easily occurred.
3
As one of the
new materials for restoring tooth defects, zirconia all-ce-
ramic crowns have no metal substrate, but high tissue
compatibility, strong corrosion resistance and excellent
mechanical properties. Meanwhile, they are not likely to
induce gingival inflammation. The color and layer of
teeth after restoration are obvious, and the color can re-
main stable for a long time, so zirconia all-ceramic
crowns have been widely applied.
4,5
The accuracy and fineness of impression directly af-
fect the production of a prosthesis and the accuracy of its
placement in the mouth.
6
As a subtractive manufacturing
Materiali in tehnologije / Materials and technology 57 (2023) 2, 149–154 149
UDK 549.514:616.314 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 57(2)149(2023)
*Corresponding author's e-mail:
frankiezamorapu@yahoo.com (Wei Li)

method, computer-aided design and computer-aided
manufacturing (CAD/CAM) is the main processing
method for zirconia all-ceramic crowns. However, the
material waste rate is up to 90 % when a fixed prosthesis
is prepared with this method. On the contrary, the
three-dimensional (3D) printing technique is an additive
manufacturing method, which greatly saves materials.
7,8
The marginal fitness of metal crowns made with the 3D
printing technique is significantly better than that of cast
metal crowns.
9
Until now, the clinical effects of zirconia
all-ceramic crowns made with the 3D printing and
CAD/CAM on the anterior-tooth aesthetic restoration
has remained largely unknown.
Therefore, the aim of this study was to compare the
restoration effects of zirconia all-ceramic crowns made
with the two impression techniques, and their influences
on periodontal tissues and aesthetics. The findings pro-
vide valuable evidence for further material design and
preparation.
2 EXPERIMENTAL PART
2.1. Baseline clinical data
This study was approved and supported by the medi-
cal ethics committee of our hospital. A total of 85 pa-
tients with anterior tooth defects treated in our hospital
from January 2018 to October 2019 were selected. They
selected the zirconia all-ceramic crowns made with
CAD/CAM (control group) or 3D printing (observation
group) according to their own will.
The inclusion criteria were as follows: 1) Patients
aged 18–60 years; 2) those diagnosed with anterior tooth
defects and receiving routine single-crown restoration;
3) those who had an intact root canal or had received
root-canal therapy; 4) those with no malformation and a
normal structure of the maxillofacial region as shown by
X-ray, and alveolar resorption or absorption of no more
than 1/3; 5) those without systemic chronic diseases af-
fecting the health of periodontal tissues, such as diabetes
mellitus; and 6) those who had the basic understanding
of the treatment methods and adverse reactions, signed
the informed consent and voluntarily received restora-
tion.
The exclusion criteria included: 1) Patients compli-
cated with oral infection and/or systemic infectious dis-
eases; 2) those complicated with periodontal disease,
pulp inflammation or chronic inflammation of root apex;
3) those with bad habits such as sleep bruxism and hard
biting; 4) those with blood coagulation disorders;
5) those complicated with severe cardiovascular or
cerebrovascular diseases; 6) those who had poor compli-
ance in treatment and could not cooperate well; or
7) those with incomplete clinical data, or breastfeeding
or pregnant women.
2.2. Methods
All all-ceramic crowns were made by the same tech-
nician, and the remaining operations were performed by
the same physician. Before treatment, conventional treat-
ment, such as extraction of an affected tooth and
periodontal scaling, was conducted for both groups. The
color of crowns was selected using the Vitapan 3D-Mas-
ter shade guide (VITA Zahnfabrik, Germany) under nat-
ural light, and the crowns were prepared in line with the
requirements of all-ceramic crowns. The points, lines
and corners had to be rounded, and the rounded right-an-
gled shoulders had to be at the margin. The margin of the
prosthesis was clearly and accurately exposed through
single-line gingival retraction. The gingival retraction
cord was removed before the final impression, and the
gingival sulcus was rinsed and blown dry.
For the control group, a silicone rubber impression
was made before tooth extraction. The impression mate-
rials were mixed by the same nurse in strict accordance
with the instructions. The articulation registration of the
prepared silicone rubber impression, superhard gypsum
model and silicone rubber was checked correctly, and
then the design list was filled out. Then a Lava Plus zir-
conia ceramic block (3M, St Paul, MN, USA) was cut
with a CAD/CAM cutting machine (DWX-50, Roland,
Japan) to prepare an all-ceramic crown, and sintered in a
sintering furnace, followed by external dyeing by the
technician based on the color matching after secondary
sintering. For the observation group, the mouth was
scanned using CEREC Omnicam (Sirona, Germany) to
obtain the optical digital model of the abutment tooth.
Then the model was sent to the Artifice Room by the
CEREC network. After design, a 3D-printed resin model
was made, and the zirconia all-ceramic crown was pre-
pared through stereolithography, followed by thermal
debinding and sintering.
The patient wore the unglazed zirconia all-ceramic
crown. Its shape, contact point position, adjacent tight-
ness and marginal fitness were checked, and the occlusal
gap was adjusted. Then the all-ceramic crown was
glazed, ground, kept away from moisture and bonded
with resin binder. The occlusal function was checked or
adjusted again, and the patient was instructed to clean
the interdental space regularly using dental floss, and ex-
amined regularly.
2.3. Assessment of short-term restoration effects
One month after restoration, the gingival marginal fit-
ness was assessed based on the following grading sys-
tem: Grade I (the prosthesis and abutment tooth have
good anastomosis, and there is basically no gap. The
probe cannot be stuck into or is just slightly stuck into
the gap); Grade II (there is a small gap between the pros-
thesis and abutment tooth where a probe can be in-
serted); Grade III (there is a large gap between the pros-
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150 Materiali in tehnologije / Materials and technology 57 (2023) 2, 149–154

thesis and abutment tooth where a probe can be freely
inserted).
The integrity of the prosthesis was assessed based on
the following grading system: Grade I (without abnor-
mality of the prosthesis); Grade II (small cracks or folds
on the prosthesis, not affecting the aesthetics); Grade III
(fracture, porcelain collapse or exfoliation of the prosthe-
sis, visible cracks or folds on the prosthesis).
The tooth color matching was assessed based on the
following grading system: Grade I (the shape, gloss,
color and brightness of the prosthesis are basically the
same as those of the adjacent teeth); Grade II (the color
and gloss of the prosthesis are slightly different from
those of the adjacent teeth, but the shape and brightness
basically show no differences, not affecting the aesthet-
ics); Grade III (there are greater differences between the
prosthesis and adjacent teeth).
2.4. Evaluation of periodontal health indices
Before restoration and one year after restoration, the
periodontal health was detected mainly by probing.
Bleeding index (BI): A blunt periodontal probe was
gently inserted into the gingival sulcus or periodontal
pocket bottom at a 45° angle to the tooth surface, and
taken out. The gingival bleeding was observed after 30 s.
Healthy gums: 0 point; no bleeding but inflammatory
changes in the gingival color after probing: 1 point;
punctate gingival bleeding after probing: 2 points; bleed-
ing spreading along the gingival margin after probing: 3
points; bleeding overflowing gingival sulcus after prob-
ing: 4 points; spontaneous gingival bleeding: 5 points.
Probing depth (PD): The distance between the
gingival margin and the gingival sulcus or periodontal
pocket bottom; the buccal and lingual mesial/median/dis-
tal gingival papillae of each tooth were checked using
the probe parallel to the long axis of the tooth with a
force of no more than 209, and the average of six sites
was taken.
Attachment loss (AL): In the case of gingival reces-
sion, AL = distance from the cemento-enamel junction to
the gingival margin + PD; in the case of no gingival re-
cession, AL = distance from the cemento-enamel junc-
tion to the gingival margin – PD.
Gingival index (GI): Normal gingival shape and
color: 0 point; mild gingival inflammation, mild redness
with edema, and no bleeding: 1 point; moderate gingival
inflammation, redness or small ulcer formation, and
proneness to bleeding: 2 points; severe gingival inflam-
mation, redness and swelling, bleeding and congestion
without being touched: 3 points.
Plaque index (PI): The tooth surface was slightly
scratched using the probe combined with visual inspec-
tion. No plaques: 0 point; plaques found on the surface
of prosthesis at the gingival sulcus: 1 point; a moderate
number of plaques visible to the naked eye: 2 points; a
large number of soft mucinous deposits: 3 points. The
examinations were performed by two professional den-
tists receiving uniform training, under natural light, and
the data were recorded and checked by two dental interns
receiving uniform training. The same batch of examina-
tion instruments passing the standard consistency check
(Kappa >0.8) was used.
2.5. Assessment of functional recovery
Before restoration and one year after restoration, the
masticatory function was evaluated. The patients were
instructed to chew a certain amount of food within a cer-
tain time, and the masticatory function was detected by
weighing. The highest efficiency was 100 %, and a
higher efficiency meant a better recovery of the mastic-
atory function. Language function: The patients gave a
score to the language function according to their daily
conversations. The highest score was 10 points, and a
higher score indicated a better recovery of the language
function.
2.6. Assessment of long-term therapeutic effects
One year after restoration, the long-term therapeutic
effects were evaluated based on the following grading
system: Markedly effective: The teeth were arranged
neatly, and both masticatory and language functions
were recovered. There was no pain, and no aching feel-
ing was caused by a hot/cold stimulus at the crown mar-
gin. Effective: The teeth were arranged normally, and the
masticatory function was obviously recovered. Discom-
fort was caused by chewing hard food, and temporary re-
actions were induced by a hot/cold stimulus at the crown
margin. Ineffective: Loosening, fracture and even exfoli-
ation of prosthesis, masticatory dysfunction, and further
restoration was needed. Total effective rate = (markedly
effective cases + effective cases)/total cases × 100 %.
2.7. Evaluation of aesthetic restoration effects
One year after restoration, the aesthetic restoration
effect was evaluated by the patients using self-made
questionnaires. Aesthetic: The patient felt comfortable,
satisfied with the external shape of the full crown with-
out color difference, and behaved naturally and nicely
when talking and smiling. Acceptable: The patient felt
fine and satisfied with the external shape of the full
crown, but there was small color difference, so the pa-
tient was a little cautious when smiling. Not aesthetic:
The patient felt uncomfortable. There was light discolor-
ation, loosening or even fracture, and the patient was un-
willing to expose teeth when smiling.
2.8. Statistical analysis
The SPSS 16.0 software was used for a statistical
analysis. The count data were expressed as (n, %), and
the chi-square test was employed for comparisons be-
tween the two groups. The quantitative data were ex-
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Materiali in tehnologije / Materials and technology 57 (2023) 2, 149–154 151

pressed as the mean ± standard deviation (x ± s). In the
case of comparisons between the two groups at multiple
time points, the intergroup difference and the time differ-
ence in the measured value at each time point were first
explored with repeated measures analysis of variance. If
there were differences, the SNK-q test was further used
to compare the time differences for each group, and the
LSD-t test was utilized to compare the intergroup differ-
ences at each time point. The test level was = 0.05, and
two-tailed P < 0.05 suggested that the difference was sta-
tistically significant.
3 RESULTS
3.1. Baseline data
In the control group, there were 43 patients, includ-
ing 24 males and 19 females aged 18–59 years, with an
average age of (36.58 ± 10.27) years. In the observation
group, there were 42 patients, including 21 males and 21
females aged 19–60 years, with an average age of (37.16
± 10.42) years.
3.2. Short-term restoration effects
There was no significant difference in the integrity of
prosthesis between the two groups (P > 0.05). The
gingival marginal fitness of the observation group was
better than that of the control group, while the tooth
color matching of the control group was better (P < 0.05)
(Table 1).
3.3. Periodontal health indices
Before restoration, there were no significant differ-
ences in BI, PD, AL, GI and PI between the two groups
(P > 0.05). One year after restoration, BI, PD, AL, GI
and PI all declined in the two groups, more significantly
in the observation group (P < 0.05) (Table 2).
3.4. Functional recovery
Before restoration, the masticatory and language
functions showed no significant differences between the
two groups (P > 0.05). One year after restoration, both
functions were improved in the two groups, especially in
the observation group (P < 0.05) (Table 3).
3.5. Long-term therapeutic effects
The total effective rates of the control and observa-
tion groups were 97.67 % and 100 %, respectively. No
significant difference was found in the long-term clinical
efficacy between the two groups (P > 0.05) (Table 4).
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152 Materiali in tehnologije / Materials and technology 57 (2023) 2, 149–154
Table 1: Short-term restoration effects
Group n Gingival marginal fitness (n, %) Integrity of prosthesis (n, %) Tooth color matching (n,%)
Grade I Grade II Grade III Grade I Grade II Grade III Grade I Grade II Grade III
Control 43 30(69.77) 11(25.58) 2(4.65) 36(83.72) 6(13.95) 1(2.38) 41(95.35) 2(4.65) 0(0.00)
Observation 42 40(95.24) 2(4.76) 0(0.00) 38(90.48) 4(9.52) 0(0.00) 30(71.43) 11(26.19) 1(2.38)
 2
9.649 1.443 8.925
P 0.008 0.486 0.012
Table 2: Periodontal health indices
Group n
BI (point,  ± s) PD (mm,  ± s) AL (mm,  ± s) GI (point,  ± s) PI (point,  ±s)
Before
restoration
1 year af-
ter restora-
tion
Before
restoration
1 year af-
ter restora-
tion
Before
restoration
1 year af-
ter restora-
tion
Before
restoration
1 year af-
ter restora-
tion
Before
restoration
1 year af-
ter restora-
tion
Control 43
3.82 ±
0.57
1.64 ±
0.25*
3.41 ±
0.37
2.38 ±
0.29*
2.53 ±
0.31
1.87 ±
0.21*
1.75 ±
0.23
0.82 ±
0.14*
2.06 ±
0.31
1.48 ±
0.22*
Observa-
tion
42
3.86 ±
0.55
0.93 ±
0.16*
3.38 ±
0.36
1.94 ±
0.21*
2.48 ±
0.29
1.33 ±
0.15*
1.73 ±
0.22
0.46 ±
0.07*
2.09 ±
0.32
0.74 ±
0.13*
t 0.329 15.554 0.379 7.996 0.768 13.614 0.410 14.939 0.439 18.823
P 0.743 0.000 0.706 0.000 0.445 0.000 0.683 0.000 0.662 0.000
AL: attachment loss; BI: bleeding index; GI: gingival index; PI: plaque index; PD: probing depth *P < 0.05 vs. before restoration
Table 3: Functional recovery
Group n
Masticatory function (%,  ± s) Language function (point,  ±s)
Before restoration 1 year after restoration Before restoration 1 year after restoration
Control 43 41.58 ± 2.63 83.92 ± 3.86* 6.72 ± 0.81 8.55 ± 0.93*
Observation 42 41.36 ± 2.59 89.78 ± 4.65* 6.69 ± 0.78 9.12 ± 1.04*
t 0.388 6.328 0.174 2.665
P 0.699 0.000 0.862 0.009
*P < 0.05 vs. before restoration

3.6. Aesthetic effects
The aesthetic effect showed no significant difference
between the two groups (P > 0.05) (Table 5).
4 DISCUSSION
Zirconia all-ceramic crowns not only exhibit high
marginal fitness and biological compatibility, but also a
better aesthetic effect than that of porcelain-fused-
to-mental crowns.
10
The placement, gingival marginal fit-
ness, qualification rate of occlusal relation and prosthesis
appearance of zirconium dioxide all-ceramic crowns
made with CEREC intraoral scanning combined with 3D
printing are all superior to those of the crowns made with
silicone rubber impression.
11
Marcel et al. found that the
zirconia all-ceramic crowns made with CAD/CAM and
3D printing had intact structures without obvious de-
fects, and the outer surfaces were smooth without visible
sticky powders or cracks.
12
The porcelain white
3D-printed all-ceramic crowns are slightly inferior to the
CAD/CAM all-ceramic crowns in the restoration of the
tooth color, but the marginal and internal fitnesses of the
former are better. The results of this study are consistent
with those of the above references. As a commonly used
oral impression material, silicone rubber is characterized
by stable chemical properties, high fluidity, precision
and strength, making it easy to obtain a complete and
clear impression. Moreover, it has strong abilities of
elastic recovery and detail reproduction. Although the
size change in the silicone rubber impression remains
stable at 0.5 % within 24 h, the operation may be diffi-
cult due to the complicated manufacturing process, or in-
formation deviation can be caused due to gingival sulcus
bleeding, salivary secretion and infusion of gypsum
models. Additionally, the impression and models may
suffer from deformation during disinfection, storage and
transportation. Moreover, wear and tear are inevitable in
the process of gypsum model trimming, thus affecting
the restoration effect.
13
On the contrary, a 3D-printed
model is easy to measure while avoiding wear and tear,
which can ensure the accuracy of data.
Excessive material consumption is the main disad-
vantage of CAD/CAM machining. The model of cutting
head limits the shape of prosthesis, and the cut material
cannot be reused, resulting in a great waste. 3D printing
allows accurate and efficient restoration while remedying
the shortcomings of the CAD/CAM subtractive cutting
mode.
14
More importantly, a high-precision prosthesis is
more beneficial to periodontal restoration.
15,16
In a study
on the performance of 3D-printed individualized zirconia
implants in adult Beagle dogs, Zhu et al. found that the
bending resistance, compressive strength and elastic
modulus of 3D-printed zirconia materials were closer to
those of natural bone tissues.
17
There was no cyto-
toxicity, and the implant could be put in place in the ex-
traction socket without inflammation or exfoliation,
firmly bound to the surrounding bone tissues. Likewise,
in this study, 3D-printed zirconia all-ceramic crowns
were more conducive to the recovery of periodontal tis-
sues and alleviation of gingival inflammation. Zirconia
materials have high biological compatibility without the
toxicity to soft tissues, and do not lead to complications
such as allergy, gingival staining or hemorrhagic necro-
sis. Besides, the data measured by 3D printing are more
accurate and the gingival marginal fitness is better, so the
3D-printed zirconia all-ceramic crowns fit better and
have better coordination with the original teeth.
If not treated promptly, dentition defects reduce or
eliminate the masticatory function, increase the burden
on the gastrointestinal tract, affect the digestive function
and weaken the language function of patients. In addi-
tion to the masticatory and language functions, the aes-
thetic restoration effect of a fixed prosthesis has long
been the concern of the patients with dentition defects.
18
Almarza et al. reported that compared with casting
all-ceramic crowns, zirconia all-ceramic crowns greatly
improved the masticatory function and aesthetics of pa-
tients after restoration.
19
Beisdes, Della et al. found that
the occlusal relationship and aesthetics of the patients
with dentition defects were significantly better, and the
recovery time of dental function was significantly shorter
after 3D-printed zirconia restoration than after conven-
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Materiali in tehnologije / Materials and technology 57 (2023) 2, 149–154 153
Table 4: Long-term therapeutic effects
Group n
Markedly effective
(n,%)
Effective
(n,%)
Ineffective
(n,%)
Total effective rate
(n,%)
Control 43 35(81.40) 7(16.28) 1(2.33) 42(97.67)
Observation 42 39(92.86) 3(7.14) 0(0.00) 42(100.00)
 2
2.805 0.988
P 0.246 0.320
Table 5: Aesthetic effects
Group n Aesthetic (n,%) Acceptable (n,%) Not aesthetic (n,%)
Control 43 32(74.42) 9(20.93) 2(4.65)
Observation 42 34(80.95) 7(16.67) 1(2.38)
 2
0.632
P 0.729

tional dentition restoration.
20
Similarly, in this study, the
masticatory and language functions of the observation
group were significantly superior to those of the control
group. The 3D-printed zirconia all-ceramic crowns ex-
hibit better gingival marginal fitness, compatibility and
coordination with the original teeth. Besides, the
long-term clinical efficacy and aesthetic effects showed
no significant differences between 3D-printed and
CAD/CAM zirconia all-ceramic crowns, possibly be-
cause the sample size was not large enough, producing
biased results. In addition, we found that the 3D-printed
zirconia all-ceramic crowns exhibited better gingival
marginal fitness, enhancing the comfort of patients, but
the recovery of tooth color was slightly inferior. There-
fore, there may be no significant differences in the final
evaluation results of the aesthetic effect.
5 CONCLUSIONS
In conclusion, both 3D-printed and CAD/CAM zirco-
nia all-ceramic crowns exhibited obvious cosmetic resto-
ration effects on anterior teeth. However, 3D-printed zir-
conia all-ceramic crowns have better gingival marginal
fitness, which can better benefit the periodontal tissue re-
covery, relieve gingival inflammation, and improve the
masticatory and language functions. In the future, we
will further increase the sample size and research cen-
ters, and improve the evaluation standards, aiming to ob-
tain more accurate and reliable results.
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F. LI, W. LI: EFFECTS OF THREE-DIMENSIONAL-PRINTED ZIRCONIA ALL-CERAMIC CROWNS ...
154 Materiali in tehnologije / Materials and technology 57 (2023) 2, 149–154