What is the survival rate of dental implants in Turkey? A systematic review

Abstract

Objectives: The purpose of this study was to examine the failures of dental implants in Turkey and to investigate the complications, which may lead to implant loss. Study Design: The Systematic review was performed in accordance with PRISMA statement and Cochrane guidelines. PubMed, Google Scholar, Cochrane Library, TUBITAK ULAKBIM databases were searched for both in English and Turkish up to 2015. Data on implant failure, demographic variables and outcomes were included. Nonclinical and animal reports were excluded. Search was conducted by two authors and conflicts were resolved by a third reader. Results: Seventeen reports were satisfied the inclusion criteria. In total, 1764 (51.19% female and 48.81% male) participants were included. A total of 4487 implants were used. Total implant success was 97.48% (61 early and 52 late failures) in a follow-up period for 42.71 ± 33.78 months. The failure reasons were infection (38.9%), lack of osseointegration (44.4%), implant fractures (5.8%), periimplantitis (1.76%), sensory disturbances (2.65%). Conclusion: Immediate and late implantation has similar failure rates and failure rates may increase with time. Implants have similar survival rates with the literature in Turkey region as well. It was observed that few reports with limited data were reported considering the high number of implants placed in the Turkey.

Full text

What is the survival rate of dental implants in Turkey? A systematic review.
Fatih Cabbar1, Muammer Çağrı Burdurlu1, Nevzat Sezer Işiksaçan1, Berkem Atalay2, Gonca Duygu
Çapar3
1Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, University of Yeditepe, Bagdat cd No:238,
Goztepe, Kadikoy, Istanbul, Turkey
2Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, University of Istanbul, Turgut Ozal cd No:118,
Fatih, Istanbul, Turkey
3Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, University of Trakya, Balkan Yerleskesi, Edirne,
Turkey
Abstract
Objectives: The purpose of this study was to examine the failures of dental implants in Turkey and to
investigate the complications, which may lead to implant loss.
Study Design: The Systematic review was performed in accordance with PRISMA statement and
Cochrane guidelines. PubMed, Google Scholar, Cochrane Library, TUBITAK ULAKBIM databases
were searched for both in English and Turkish up to 2015. Data on implant failure, demographic
variables and outcomes were included. Nonclinical and animal reports were excluded. Search was
conducted by two authors and conflicts were resolved by a third reader.
Results: Seventeen reports were satisfied the inclusion criteria. In total, 1764 (51.19% female and
48.81% male) participants were included. A total of 4487 implants were used. Total implant success was
97.48% (61 early and 52 late failures) in a follow-up period for 42.71 ± 33.78 months. The failure reasons
were infection (38.9%), lack of osseointegration (44.4%), implant fractures (5.8%), periimplantitis
(1.76%), sensory disturbances (2.65%).
Conclusion: Immediate and late implantation has similar failure rates and failure rates may increase
with time. Implants have similar survival rates with the literature in Turkey region as well. It was
observed that few reports with limited data were reported considering the high number of implants
placed in the Turkey.
Keywords: Dental implant, Failure rates, Systematic review
Accepted on November 04, 2017
Introduction
Oral rehabilitation with dental implants is a well-documented
procedure. Since osseointegration was first described by
Branemark et al. [1], dental implants are being used with all
kinds of prosthesis as well as a maxillofacial prosthesis. In
later years treatment with dental implants has been examined
in many long-term clinical studies, focusing primarily on
implant survival [2-4]. The current literature shows high
implant success rates ranging from 90% to 97% [5]. However,
the terms survival and success are generating confusions and
used incorrectly even in many academic studies [4]. There are
many studies on success and survival rates of implants because
of the large number of variables, such as surgical techniques,
prosthetic variations, materials used, patient-related factors and
follow-up periods. In addition, there were different protocols
and criteria reported for the definition of implant success and
survival, and there is no consensus or international
standardization [3,6-11].
Despite the high success or survival rates, failures may occur
[3]. Failure is determined when the performance of a dental
implant falls below a particular level [12]. Dental implant
failures may originate from different epidemiological causes
and can be biological, mechanical, iatrogenic or due to
insufficient patient adaptation. Failures are classified as early
and late failures. If the failure occurs before osseointegration
and at the time of the abutment connection, it is considered as
an early failure; if it occurs after osseointegration, during
occlusal loading, then it is regarded as a late failure [12-14].
There were different causes of failures reported for early and
late implant failures. While early failures were mostly related
to lack of osseointegration caused by soft tissue involvement
between implant and bone, infection, different kinds of
traumas, delayed healing or insufficient osseointegration
ISSN 0970-938X
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Biomed Res 2018 Volume 29 Issue 3 485
Biomedical Research 2018; 29 (3): 485-495

period and insufficient keratinized gingival width, the late
failures are a result of breakdown of osseointegration by
reasons such as, trauma, restorative principles, infection or
mechanical complications [14-17].
Dental implants are being used for more than 20 years in the
Turkey Republic. The assumed dental implant placement is
about 350,000 annually, which is about 4% of the total
population, and it is increasing [18]. However, there isn’t any
review, which examines the failure rates of implants, exist for
this region. The purpose of this study is to examine failure
rates of dental implants in Turkey and to investigate the
complications, which may lead to implant loss.
Methods
This systematic review was performed in accordance with the
PRISMA statement (Preferred Reporting Items for Systematic
Review and Meta-analyses) [19] and Cochrane guidelines. The
clinical questions were divided and categorized according to
the PICO strategy (Participant, Intervention, Comparison, and
Outcome) (Table 1).
Table 1. PICOS (Participants, Interventions, Comparisons, Outcomes,
Study Design).
Participants Generally healthy patients with total or partially
edentulous dental arches
Interventions Dental implants, single or multiple implants, implant
supported prosthesis
Comparison Outcomes Cumulative survival of dental implants, incidence of
implant-related complications
Study Design Randomized controlled trial, prospective cohort study,
retrospective cohort study.
Language: English and Turkish; The primary objective of the study is to evaluate
the survival and failure rates of dental implants in Turkey.
Objectives
The research question was ‘What is the survival rate of dental
implants in Turkey?’ The main objective of this review was to
fill the gap in the literature related to the clinical applications
of dental implants and their common complications in Turkey
region. This data would be useful for both clinicians and
academicians for further studies and making decisions in
treatment modalities.
Search Strategy
PubMed/MEDLINE, Google Scholar, Cochrane Library and
TUBITAK ULAKBIM DergiPark databases were searched for
relevant articles published in Both English and Turkish with no
date restriction up to 2015 with the keywords Dental Implant,
Failure, Survival, Success, Turkey and Turkish in different
combinations.
The inclusion criteria were; papers in English or Turkish,
published in peer review journals, which reported dental
implant failures. The articles related to human subjects. For
this review, the implant failure was regarded as the total loss of
the dental implant.
The exclusion criteria were: papers written in other languages,
animal studies, in vitro studies, implants performed with
maxillary sinus floor augmentation procedures, distraction
osteogenesis, bone blocks or implants performed with bone
grafts, non-oral implants and case reports and reviews.
The literature search was conducted by two independent
authors (FC and MCB). The abstracts were first analysed. The
papers were extracted according to the exclusion criteria from
abstracts and full-text articles. All duplicates were removed.
Two authors independently judged articles and collect the data
before a decision was made and conflicts, if any was resolved
by analyses of a third reader (GDC).
From each paper included, relevant demographic and outcome
data were extracted such as year of publication, the number of
patients, gender, mean patient age, the number of implants
performed, mean follow-up, surgical procedure, and outcomes,
type of implant loading, the number of implant failures, failure
times and reasons. The failure of the implant regarded as the
total loss of the implant.
Quality Analysis
For increasing the reliability and to evaluate the risk of bias,
the analyses of quality of the included studies were done, as in
the study conducted by Moraschini et al. [4]. The methodology
used was proposed by Nguyen et al. [20] combined with
Needleman guide [21] and the Cochrane recommendations
[22]. Table 2 shows the criteria assessed with their potential
scores. When these scores added together, they generate a
maximum score of 16 points. A score of >12 was regarded as
low, a score between 10 and 12 was regarded as moderate and
<10 was regarded as high.
Table 2. Criteria for quality analyses.
Criteria Maximum
score
Sample size
2
Studies with samples <100 participants=1
Studies with samples ≥ 100 participants=2
Follow-up time
2
Studies without a period of follow-up=1
Studies with a period of follow-up=2
Selection criteria
2
Selection criteria not mentioned or poorly defined=1
Selection criteria well defined=2
Description of population
1
Studies that did not make available the age or gender of
patients=0
Studies that made available the age and gender of patients=1
Cabbar/Burdurlu/Isiksaçan/Atalay/Duygu Çapar
486 Biomed Res 2018 Volume 29 Issue 3

Available statistical methods
2
Studies that did not make available the statistical methods
used=0
Studies that made available the statistical method used, but did
not describe them clearly=1
Studies that made available the statistical method used, and
described them clearly=2
Criteria of success
1
Studies that used a scale of success for evaluation of implants
and described it=1
Description of objectives
2Objective of study undefined=1
Objective of study clearly defined=2
Randomized study
1
Randomized clinical trials (RCT)
Number of implants evaluated
2Studies with samples <100 implants=1
Studies with samples ≥ 100 implants=2
Conclusions
1
If the conclusions are in accordance with the objective of the
study
Figure 1. Search strategy and screening process.
Statistical Analyses
After evaluation of the included articles, considerable
heterogeneity was present in the study designs, therefore it was
not possible to perform reliable meta-analyses. Because of this,
descriptive type of methods such as; mean, standard deviation,
frequency, percent, and distribution, were used. The statistical
analyses performed by NCSS (Number Cruncher Statistical
System) 2007 Statistical software (Utah, USA) program.
Results
The initial search yielded 454 titles in Medline/Pubmed,
Cochrane Library and Google Scholar and 333 titles in
TUBITAK ULAKBİM DergiPark. After the initial evaluation,
121 papers were selected. After careful reading 104 articles
were excluded and remaining 17 articles were included in this
review [3,11,23-37]. The included studies were published
between 2003 and 2015. The process for study selection and
screening and the reasons for exclusion are shown in Figure 1.
A total of 17 papers reported the implant failure were included
in this review. Details of the studies were listed in Table 3a and
3b. The mean follow-up time was 42.71 ± 33.78 months (Min:
12, Max: 120). Eleven prospective studies and 6 retrospective
studies were included. The studies included 1764 patients with
a mean age of 46.78 ± 7.39 years (between 18 and 80 years).
Of these patients 903 (51.19%) were female and 725 were
male (48.81%).
Table 3a. Demographic data and the analyses of implant failure
included in 17 articles.
17 articles; Number of total patients 1764
Female 903 (51.19%)
Male 725 (48.81%)
Mean age 46.78 ± 7.39 (Min: 18; Max: 80)
Number of implants 4487
Maxilla 2074 (46.22%)
Mandible 2455 (53.78%)
Follow-up 42.71 ± 33.78 (Min: 12; Max: 120)
Implant fracture 4 (0.09%)
Early implant failure 61 (53.98%)
Late implant failure 52 (46.02%)
Total implant failure 113 (2.52%)
Survival rate 97.48%
Table 3b. Details of the studies included in this review. F: Female; M: Male; NR: Not Reported.
Author Year Study Design &
Follow-up time
No. Of
Participants &
Gender
Age range
Mean Age
Number of
implants &
implant
system
Place of
implantation
Healing
period
for
loading
(months)
Timing of
implantation
Early failure Late failure Place of
Failure
What is the survival rate of dental implants in Turkey? A systematic review
Biomed Res 2018 Volume 29 Issue 3 487

Ozkan et al.
2007
Prospective
Cohort 3 years
63 (25M/ 38 F) 18-63 46,9,
46 ± 9
203 (105
Straumann,
53 Camlog,
45 Frialit)
Maxilla 91
Mandible
112
Mandible
3,
Maxilla 6
Late
implantation
1 Straumann
implant,
Female patient
(infection)
NR
Gulsahi et
al. 2007
Prospective
Cohort 12
month
14 (5M/9F) 23-59 41,1 28 (Frialit) Maxilla 28
Mandible 0
6 Late
implantation
5 Frialite
implant (lack of
Osseointegrati
on)
5
Maxilla
Soydan et
al. 2013
Prospective
Cohort, 51,6
months early
implantation,
61,9-month
immediate
implantation
36 (16M/20F) NR 55,7 ±
28,5
50
(Straumann)
Maxilla 33
Mandible 17
Mandibul
a 2,
Maksilla
4
26
immediate
implantation
s, 24 one
month after
extraction
1 Straumann implant NR
Simsek et.
Al. 2003
Prospective
Cohort 7
months
20 (NR) NR 70 (NR) NR NR Immediate
implantation
6 implants (4
had previous
periodontitis, 2
had periapical
infection
4
Maxilla,
2
Mandibl
e
Akın et al.
2009
Prospective
Cohort 24
months
32 (14M/18F) 19-62 NR 106 (29
Straumann,
+7 Miss, !8
Biolok, 12
Biotech)
NR NR Late
implantation
1 implant neck
fracture
NR
Eltas et al.
2013
Prospective
Cohort 16
months
79 (34M/45F) 20-78
45,19
193
(Straumann,
Xive)
Maxilla 87
Mandible
106
Mandibul
a 3,
Maxilla 6
Late
implantation
5 implant
(periimplantitis)
1 implant neck
fracture (16 months
later)
NR
Celebi et al.
2012
Retrospective
Cohort 24
months
168 (72M/96F) 18-80 44 549
(Straumann)
Maxilla 271
Mandible
278
NR 542 Late
implantation
, 8
immediate
implantation
2 Straumann
implant (1
performed in
extraction
socket which
implant threads
were exposed,
1 performed by
internal sinus
lifting)
1 strauman implant NR
Bolukbası
et al. 2013
Prospective
Cohort 3
months
150 (93M/57F) 29.03 ±
5,47 33,98
± 4,57
34,48 ±
5,58 (3
groups)
403 (NR) NR NR Late
implantation
3 implant
failure
2 implant failure NR
Bilhan et al.
2012
Retrospective
Cohort 24
months
89 (36M/53F) 59,63 ±
9,62, 54,97
± 12,24 (2
groups)
278 (126
Astra Tech,
71
Straumann,
51 Biolok, 30
Zimmer)
NR NR Late
implantation
6 implant
failure
3 implant failure 6
Maxilla,
3
Mandibl
e
Piskin et al.
2010
Retrospective
Cohort, Multi
centered, 4
years
116 (NR) NR 204 (NR) Maxilla 97
Mandible
107
NR Late
implantation
1 implant fracture (2
years)
NR
Bilhan et al.
2011
Retrospective
Cohort, 3 years
117 (45M/72F) NR 46,94 165 (31
Astra Tech,
79
Straumann,
34 Biolok, 21
Xive)
Maxilla 88
Mandible 77
4-06 İmmediate
implantaiton
9 implant
failure
1 implant failure 3
mandibl
e, 7
maxilla
Atalay et al.
2013
Retrospective
Cohort, 5 years
72 (28M/44F) 22-74 NR 110 (NR) Maxilla 60
Mandible 50
3 immediate
implantation
4 implant
failure
1 implant failure
(periimplantitis)
NR
Güncü et al.
2008
Prospective
Cohort, 12
months
12 (4M/8F) 30-55
41,09 ±
8,46
24
(Branemark)
Maxilla 0
Mandible 24
0-3 Late
implantation
.
1 (early
loading)
1
Mandibl
e
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488 Biomed Res 2018 Volume 29 Issue 3

Arısan et al.
2010
Retrospective
Cohort, 9,1
years
139 (66M/73F) 21-80 55,3 316 (235
Straumann,
81 Xive)
Maxilla 161
Mandible
155
Mandible
3,
Maxilla 6
Late
implantation
16 implant
failure (3
removed
because of
paresthesia, 2
infection, 4
lack of
osseointegratio
n with gingival
exposure, 7
lack of
integration
without
symptoms)
2 implant failure (1
aggressive bone loss
at first year, 1
periimplantitis after
50 months)
NR
Geckili et
al. 2014
Retrospective
Cohort, 10
years
616 (269M/
347F)
52,7 ±
13,59
1656
(Strauman,
Astra tech,
Biohorizon)
Maxilla 656
Mandible
1000
NR NR 38 implant failure (9
between 1-3 years,
11 between 3-5
years, 18 more than
5 years p<0.05)
22
mandibl
e, 16
maxilla
Karabuda
et al. 2011
Prospective
Cohort, 15
months
22 (7M/15F) 24-58
46,68
96 (48
Straumann,
48
Straumann
SLA)
NR Mandible
8,
Maxilla
12
Late
implantation
1 (SLA group) 1
maxilla
Turkyılmaz
Ilser 2006
Prospective
Cohort, 3 years
19 (11M/8F) 20-55 39 ±
10,5
36
(Branemark)
Maxilla 36
Mandible 0
1 Late
implantation
2 implant
failure
2
maxilla
A total of 4487 dental implants were performed in these
patients. There were 9 different commercial brands of implants
used: ITI, (Straumann AG, Waldenburg, Switzerland), Astra
Tech (Astra Tech AB, Mölndal, Sweden), Biolock (Biolock
International Inc, Deerfield Beach, Fla), Brånemark System
(Nobel Biocare AB, Göteborg, Sweden), Frialit (Friatecü
Mannheim, Germany), Mis (Mis Implant Tech, Savion Israel),
Zimmer (Carlsbad, CA, USA), Biohorizon (Biohorizon,
Birmingham, AL, USA), Xive (Dentsply Friadent, Mannheim,
Germany). Of these implants performed, 2074 (%46.22) were
in the maxilla and 2413 (%53.78) were in the mandible.
Quality Assessment
The scoring of the articles for assessing the potential risk of
bias was shown in Table 4. As a result of quality analyses, 8
studies were classified as having a low risk of bias
[3,23,30-36], 8 studies were classified as moderate
[11,24-29,33,37] and only 1 study was classified as having a
high bias risk [25]. Due to having a brief explanation about
implant failure, the only study having a high risk of bias was
not excluded from the study.
Table 4. Quality analyses of the studies included in this review.
Author Sample
Size
Follow-
up
Selection
criteria
Description
of population
Statistical
methods
described
Criteria
of
success
Descriptive
of objectives
Randomized
study
Implant
number
Conclusions Total Bias
Potential
Ozkan et al. 1 2 2 1 2 0 2 0 2 1 13 Low
Gulsahi et al. 1 2 2 1 2 0 2 0 1 1 12 Moderate
Soydan et al. 1 2 2 1 2 1 2 0 1 1 12 Moderate
Simsek et al. 1 0 2 0 2 0 2 0 1 1 9 High
Akın et al. 1 2 1 1 0 0 2 0 2 1 10 Moderate
Eltas et al. 2012 1 2 1 1 0 1 2 0 2 1 11 Moderate
Celebi et al. 2 2 0 1 0 0 2 0 2 1 10 Moderate
Bolukbası et al. 2 2 2 1 2 0 2 0 2 1 12 Moderate
Bilhan et al. 1 2 2 1 2 0 2 0 2 1 13 Low
Piskin et al. 2 2 2 0 2 0 2 0 2 1 13 Low
Bilhan et al. 2 2 2 1 2 1 2 0 2 1 15 Low
Atalay et al. 1 2 2 1 0 1 1 0 2 0 10 Moderate
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Biomed Res 2018 Volume 29 Issue 3 489

Güncü et al. 1 2 2 1 2 1 2 0 1 1 13 Low
Arısan et al. 2 2 2 1 2 1 2 0 2 1 15 Low
Geckili et al. 2 2 2 0 2 1 2 0 2 1 14 Low
Karabuda et al. 1 2 2 1 2 1 2 0 1 1 13 Low
Turkyılmaz Ilser. 1 2 2 1 0 1 2 0 1 1 11 Moderate
Evaluation of Implant Failures
In eleven of these studies [23-31,34-37], implants placed in
healed sockets according to standard principles [38]. In 3
articles implants were placed immediately [25,32,33]. In a
study implants were placed both immediately and in healed
sockets [28]. In one study implants were placed both
immediately and 1 month after extraction [11]. One study did
not report any implantation time [3].
Eleven of the articles included in this study used several
criteria of success such as Albrektson et al. [8], Misch et al.
[7], Zarb and Albrektsson [9]. The remaining others just
evaluated the total loss of the implant. All 17 studies reported
implant failures. The mean percentage of implant failure was
2.52% (113 implants), which shows a total survival rate of
97.48% (4374). Of these failures, 52 (46.02%) were lost after
loading (late failure), whereas 61 (53.98%) were lost before
loading (early failure). Three failed implants of the late-failure
group were placed immediately, whereas 11 of the implants
were placed in healed sockets. Twenty of the failed implants, in
early failure group, were placed immediately, whereas 40 were
placed in healed sockets. The other studies didn’t report the
implantation time for the failed implants. Distribution of the
failed implants according to the jaws were; 41 maxillae and 31
mandibles, which makes a total of 72 implants. The other
studies didn’t report any information for the remaining 41
failures. In the early failure group, the reasons for the failure of
25 of implants were not reported. The mentioned findings for
implant failures in early failure group were, 14 infections (6
had the previous infection such as periodontitis and periapical
infection), 16 lack of osseointegration (7 had no symptoms), 1
bone perforation during surgery, 1 implant placement with
sinus lifting, 1 early loading, and 3 paresthesia (in 2 patients,
both recovered at the end of 1 year). In the late-failure group,
45 of the implants’ failure reason was not reported. The
findings reported in the late failure group were, 1 implant body
fracture, 1 immediate loading, 2 implant neck fracture, 2
periimplantitis and 1 aggressive bone loss without infection.
Discussion
The aim of this systematic review was to evaluate the survival
and failure rates of dental implants in Turkey by means of
investigating studies reported data on this subject. Regarding
the methodology of this review, following inclusion/exclusion
criteria and quality analyses, 770 papers were excluded.
Randomized controlled trials are regarded as one of the most
reliable studies for clinical practice. Therefore, the most
preferred study design for systematic reviews is randomized
controlled trials [39]. Unfortunately, there wasn’t any
randomized controlled trial that met the criteria of inclusion.
Remaining articles included in this systematic review were
retrospective and prospective studies. The absence of
randomized controlled trials may increase the risk of bias.
Therefore, quality analysis was done for included studies. Only
one study had a high risk of bias [25]. However, it was
reported that narrowing the inclusion criteria increases the
homogeneity of the data [40]. Regarding the brief data about
implant failure of that study, authors decided to include it in the
present review considering inclusion criteria.
The present review showed a mean failure rate of 2.52%,
which leads to 97.48% survival rate, for a total number of 4487
dental implants in 17 studies, with a follow-up period of 42.71
± 33.78 months. Although it is still under debate, for proper
analyses of the survival rate of implants, at least 5 years of
follow-up is mandatory [41-43]. There were 3 studies which
had a follow-up period longer than 5 years in this review. In
those studies, the survival rates were 95.45% with immediate
implantation for a follow-up for 5 years [33], 94.3% with late
implantation for a follow-up for 9.1 years [35], and 93.8% for a
follow-up for 10 years (the implantation time was not reported)
[3]. In a systematic review conducted by Moraschini et al., a
mean survival rate of 91.2% was reported for studies longer
than 20 years [4]. In two other reviews, implant survival rates
were reported 97.5% up to 5 years [39] and 96.5% for 1583
implant for a follow-up of 5 years [44]. Regarding this data
Moraschini et al. suggested that survival rates of implants are
decreasing over time [4]. However, another meta-analysis,
which studied effects of smoking on success of implants,
suggested that the rate of implant failure does not increase with
time [45] In the present review, the survival rate of studies with
a follow-up shorter than 5 years was 97.83%, which is higher
than studies with a follow-up period longer than 5 years. This
finding is in line with the previous review that there might be a
slight decrease in the survival rates of dental implants over
time [4].
There were controversial findings reported in the literature
about the incidence of early and late failures. In a 19 years
follow-up retrospective study conducted by Han. et al., a
higher number of early failures were observed (57.3%) than
late failures, which is supported by other studies [14,46,47].
However, opposite findings were also reported [17,48]. These
different findings between studies can be related to different
variables, including implant systems, the level of experience,
and patient characteristics [14,49,50]. Approximately 113
(2.52%) implant failures were observed in this review for a
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490 Biomed Res 2018 Volume 29 Issue 3

total of 4487 implants. Of these failures, 61 (53.98%) occurred
before loading, while 52 (46.02%) were late failures and
occurred after loading. Therefore, a higher number of implants
were lost before loading in this review. It should be noted that
there were only 3 studies had a follow-up period more than 5
year in this review, and that 41 of the implants in late failure
group were observed in those studies [3,33,35]. In addition, 38
of the late failures were seen only in one study with a follow-
up of 10 years and 18 of those implants were lost in more than
5 years [3], which may be supporting that late failure rate
increases with time.
It was reported that the most common causes of early implant
failures were bone necrosis due to overheating, bacterial
contamination, insufficient bone quality, micro-movement of
the implant and early loading [51]. Twenty-five of the implants
in early failure group had no failure reason reported, but 14
(38.9%) of the remaining 36 implants were lost because of
infection. Possible reasons of infection were reported to be
inaccurate flap design, overheating, and placement of an
implant in an infected socket [52]. Of the failed implants, 6 had
the previous infection before implantation, such as
periodontitis and periapical lesion.
Failure due to lack of osseointegration was observed for 16
(44.4%) implants. In one of these studies, it was reported that
lack of osseointegration was more common in the maxilla, but
this result was not statistically significant [35]. In the other
study, which reported 5 implant failures due to lack of
osseointegration, the failures were also maxillary implants
[24]. It is known that poor bone quality may lead to a lack of
osseointegration and the cortical structure of the maxilla is
lower [15], which might be the reason for these failures.
Lundgren et al. suggested that early loading may lead to
insufficient osseointegration [53]. Micromotion caused by
occlusal forces may cause fibrous tissue formation between
bone and implant. However, recent studies have indicated that
immediate or early loading protocols can be used successfully
[34,54]. In the present review, there was only 1 implant failure
correlated to immediate loading, but in that study, the author
indicated that immediate functioning of the implant had no
negative effect on dental implant stability [34].
Sensory complications are mostly related to poor clinical
handling. In a systematic review conducted by Berglundh et
al., most of the included studies had reported an incidence of
1-2% sensory disturbances. In two studies sensory
complications occurred 6.9% and 19% [39]. However, most of
the sensory disturbances dissolve within 1 year. There were
few papers concerned about sensory complications persisting
more than 1 year [55,56]. In the present review, 1 study
reported postoperative pain and paresthesia for 3 implants in 2
patients [35]. The incidence of implant failure because of
sensory disturbance was 2.65% in all 113 implant failures and
0.11% patients in all 1764 patients. The authors reported that
after removing the implants the sensory disturbance had
recovered within 1 year [35].
There wasn’t any reported reason for the 45 of the implants in
the late-failure group. It was reported that periimplantitis and
overloading are the most common causes of late implant
failures [14,57,58]. Recent studies diagnosed overloading by
the presence of parafunction, mechanical complications such as
screw fracture or loosening, implant or prosthesis fracture [14].
The studies included in this review reported 2 implant neck
fractures and 1 implant fracture as a reason for late failures,
which was the 5.8% of total late failures. Implant failure
caused by implant fracture is remarkably low in the literature
[14,59,60]. But Takeshita et al. reported the fracture incidence
of 7.4%, and Chappuis et al. reported 3.2%, similar to this
review [61,62]. Berglundh et al. indicated that it is not a
common complication and its incidence is <1% for a period of
5 years. Authors suggested that the proportion of implant
failure because of implant fracture in total implant failure was
between 5-20%, which is in concordance with the present
review [39]. There are possible reasons reported for implant
fractures, which include inadequate design or adjustment of the
prosthesis, implant size, heavy occlusal loading, metal fatigue,
aggressive bone loss and galvanic activity increase over time
[14,59,60].
Peri-implantitis was evaluated by inflammatory parameters by
using assessments on probing depth, suppuration, plaque index
and bleeding on probing. It is mostly caused by poor oral
hygiene, poor clinical handling, lack of keratinized gingiva and
design of prosthesis [15,49,63,64]. There were only two peri-
implantitis cases reported for late implant failure. But it should
be noted that 45 of the late failures reported no possible causes
for those failures. One can assume that there should be more
peri-implantitis cases exist within those failures.
Regarding the time of implantation, 23 of the failed implants
were placed immediately, while 51 of them were placed in
healed sockets. It is important that none of the studies in this
review had correlated implantation times with failures. In
addition, the implantation times of the remaining 39 failures
were unknown. However, the survival rates of all studies were
known. The studies, which performed immediate implantation,
had a mean survival rate of 95.69% while studies performed
late implantation showed 96.29% in this review. These results
are similar, which indicates that time of implantation did not
have any effect on survival rates. It was reported that there
isn’t any statistically significant difference between immediate
implantation and implant placed in healed sockets [4].
Regional differences and jaw anatomy have been discussed in
terms of implant failure. Forty-one of the failed implants were
placed in the maxillary bone and 31 of them were in the
mandible. When the studies included in this review were
investigated for failure rates according to regional differences,
5 studies suggested that there were no significant differences
observed between maxillary and mandibular implants
[11,23,28,33,35]. Three of those studies reported that there
were more failures observed in maxillary implants, but there
wasn’t any statistically significant difference observed
[25,30,32]. Only one study reported significant difference for
maxillary implant failures, but in that study authors suggested
What is the survival rate of dental implants in Turkey? A systematic review
Biomed Res 2018 Volume 29 Issue 3 491

that data on prognosis of implants showed high rates of
survival can be achieved for maxillary implants [3]. The other
studies in this review did not study failure rates according to
regional differences. The majority of the studies in this review
couldn’t find any significant difference between jaws. In the
literature, some studies showed significantly higher failure
rates for maxillary implants due to poor bone quality [65,66],
while others couldn’t find any difference [67]. Chrcanovic et
al. reviewed the literature about dental implant failures and
reported that the conclusion of maxillary implants perform not
as good as mandibular ones are based mostly on old implant
surfaces, such as machined implants. However, modern
implant surfaces, like rough surfaces, seem to have improved
outcome with the maxilla than old implants. That’s probably
because of the stronger implant-bone contact with modern
surfaces [68]. Although a calculation cannot be made, most of
the implants evaluated in this review had rough surfaces, which
may relate to the view of Chrcanovic et al. [68].
Most of the longitudinal studies investigated only the survival
rates of implants. That’s because the evaluation of the success
of implants involves more complex examination and
standardization criteria. Therefore, most of the studies focused
on only the survival rate of implants. There are several criteria
of success classifications are being used in the literature, but
there isn’t any standardization exists, which makes the
comparison between studies difficult. In this review, 9 of the
17 studies used analyses of success. There were four different
criteria used in these studies, which were Albrektsson et al. [8],
Misch et al. [7], in one study authors used their own criteria
similar to Albrektsson et al. criteria [34] and in one study,
authors used both Albrektsson et al. and Misch et al. criteria.
This suggests that these two methods of success analyses are
common methods used in studies reported implant failures in
Turkey. Of the 4 studies that used only Albrektsson et al.
criteria, the mean success rate was 96.14 ± 2.21% with a mean
follow-up period of 44.00 ± 44.39 months [27,35-37]. In
accordance with this rate, of the 3 studies that used Misch et al.
success criteria mean success was 95.2 ± 2.4% with a mean
follow-up period of 67.37 ± 36.66 months [3,11,32]. These
rates are in accordance with the literature.
Taking into consideration the limitations of this study, one can
conclude that the strongest reason for implant failure is an
infection and lack of osseointegration in the Turkey Republic.
In addition, immediate or late implantation has similar
outcomes and the incidence of failure is increasing over time.
It should be noted that firm conclusions shouldn’t be made,
and the results of this systematic review have to be discussed
with caution because this review is unfortunately based on only
a limited number of failures and the lack of data does not allow
discussing implant failure in a deeper manner. Regarding the
number of implants placed in this region, doubtfully, the
failures are found to be very low. This is probably due to the
implant surgeons are not taking relevant records, having
problems with reporting data or they are not willing to report
their failures. Another outcome of this review should be to
encourage both the academicians and clinicians for reporting
and discussing their complications so that further studies with
greater numbers of subjects with more accurate data could be
made.
Conflict of Interest
There are no conflicts of interest.
Acknowledgements
The authors want to thank A. Rana Konyalıoğlu for her
contributions.
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*Correspondence to
Fatih CABBAR
Assistant Professor
Department of Oral and Maxillofacial Surgery
Faculty of Dentistry
University of Yeditepe
Turkey
Email: fcabbar@gmail.com
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Biomed Res 2018 Volume 29 Issue 3 495