Is old age a risk factor for dental implants?

Abstract

Patient's condition is distinctly different among individuals especially in the elderly. Dental implant failure seems to be a multi-factorial problem; therefore, it is unclear that aging itself is a risk factor for the placement of implants. This review reorders and discusses age-related risk factors for the success of dental implants. In dental implant treatment, chronological age by itself is suggested as one of the risk factors for success, but it would not be a contraindication. In general, reserved capacity of bone and soft tissue make it possible to establish osseointegration in the long run. Rather than aging itself, the specific nature of the disease process, such as osteoporosis or diabetes, and local bone quality and quantity at the implant site, mostly related to aging, are more important for successful dental implant treatment. This review revealed a shortage of published data for the survival and success of dental implants in older patients. More studies useful for evidence-based decision making are needed to assess the survival and success of dental implants for aged patients with a compromised condition.

Full text

MINI REVIEW
Is old age a risk factor for dental implants?
Kazunori Ikebe *, Masahiro Wada, Ryosuke Kagawa, Yoshinobu Maeda
Department of Prosthodontics and Oral Rehabilitation, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka,
Suita, Osaka 565-0871, Japan
Received 5 September 2008; accepted 3 February 2009
1. Introduction
Previous researchers have reported prognostic risk factors for
dental implants, including compromised general health (e.g.,
osteoporosis), smoking, implant location (e.g., maxilla, pos-
terior), bone quality and quantity in the recipient site, implant
length and immediate loading of the implant [1,2].
Patient’s condition is distinctly different among indivi-
duals especially in the elderly. Implant failure seems to be a
multi-factorial problem; therefore, it is unclear that aging
itself is a risk factor for the placement of implants. This
review reorders and discusses age-related risk factors for the
success of dental implants.
2. Chronological age
Age as a prognostic factor in implant success has been dis-
cussed by several authors. Older patients, theoretically, have
potentially longer healing times, more systemic health fac-
tors, and the likelihood of poorer local bone conditions [3].
In an animal study on rats, aged 6 weeks (young group), 12
weeks (adult group), and approximately 2 years (old group),
the young group showed that new trabecular bone formed
actively around the implant, and good bone contact was
achieved more rapidly than in the adult group. In contrast,
in the old group both the quantity of newly formed trabecular
bone around the implant and bone contact were less than in
the other groups. The results suggest that the rate and
volume of new bone formation around implants decrease
with increasing age [4].
However, although some studies on implant treatment in
the edentulous elderly suggested that age may be associated
Japanese Dental Science Review (2009) 45, 59—64
KEYWORDS
Dental implant;
Aging;
Jaw bone;
Diabetes;
Osteoporosis
Summary Patient’s condition is distinctly different among individuals especially in the elderly.
Dental implant failure seems to be a multi-factorial problem; therefore, it is unclear that aging
itself is a risk factor for the placement of implants. This review reorders and discusses age-related
risk factors for the success of dental implants. In dental implant treatment, chronological age by
itself is suggested as one of the risk factors for success, but it would not be a contraindication. In
general, reserved capacity of bone and soft tissue make it possible to establish osseointegration in
the long run. Rather than aging itself, the specific nature of the disease process, such as
osteoporosis or diabetes, and local bone quality and quantity at the implant site, mostly related
to aging, are more important for successful dental implant treatment. This review revealed a
shortage of published data for the survival and success of dental implants in older patients. More
studies useful for evidence-based decision making are needed to assess the survival and success of
dental implants for aged patients with a compromised condition.
#2009 Japanese Association for Dental Science. Published by Elsevier Ireland. All rights reserved.
* Corresponding author. Tel.: +81 6 6879 2956 (Business)/72 761
0596 (Home); fax: +81 6 6879 2957.
E-mail address: ikebe@dent.osaka-u.ac.jp (K. Ikebe).
availableonlineatwww.sciencedirect.com
journal homepage: www.elsevier.com/locate/jdsr
1882-7616/$ — see front matter #2009 Japanese Association for Dental Science. Published by Elsevier Ireland. All rights reserved.
doi:10.1016/j.jdsr.2009.02.001

with a higher implant failure rate [5,6], the majority of
previous studies indicated that increasing age alone is not
a contraindication for implant treatment (Table 1)[7—14].
The findings that the use of implants in older patients was not
contraindicated suggest that bone has a reserved capacity for
osseointegration.
Moy et al. [6] studied a relatively large group of patients
who had been operated on by an experienced surgeon and
found that advanced age increased the risk of implant fail-
ure; patients older than 60 years were twice as likely to have
adverse outcomes. Brocard et al. [5] analyzed cumulative
success rates in a 7-year longitudinal study in a private
practice setting with the same type of implant and found
that in patients older than 60, only a relatively small number
of implants remained.
In contrast, Meijer et al. [13] reported that Plaque Index,
Gingival Index, Bleeding Index and bone loss after 3 years
were not significantly different between younger and older
patients. The authors concluded that the clinical perfor-
mance of implant-supported overdentures in the mandible
is equally successful in younger and older patients. Mesa
et al. [14] reported that in a bivariate model, associations
were found between primary stability failure and age, sex,
smoking, oral and periodontal health status, maxillary or
mandibular placement, placement of tooth site, bone qual-
ity, and implant diameter and length. However, in a multi-
variate logistic regression model, only females (odds ratio:
1.54), implants placed in the maxilla (odds ratio: 2.7) and
implants shorter than 15 mm (odds ratio: 1.49) showed sig-
nificantly higher risk of primary implant failure. These results
suggested that age is a confounding factor associated with
stability failure of implants. August et al. [15] showed that
from a retrospective review of records at four clinical sites,
no age effect on implant success was shown between the
older and younger male groups, nor was there a significant
difference between premenopausal women and estrogen-
supplemented postmenopausal women, although there was
a significant difference between young and postmenopausal
women. Therefore, the age variable appears to be less of a
factor than does estrogen status.
3. Systemic factors
Dental implants and implant-supported prostheses are fea-
sible treatment options for older patients; however, they
present a number of problems not encountered in younger
patients, including general health problems that might con-
traindicate surgery [1]. However, absolute medical contra-
indications to implant are rare. Implant surgery presents the
same contraindications as any bone surgery, so it is very
important to identify patients who have general pathoses,
such as coronary diseases, anticoagulant treatment, dia-
betes, and osteoporosis [1].
However, patients with contraindications to implant sur-
gery never make an impact on the success or failure rate in
clinical statistics because patients with these general health
problems never undergo an operation and would not be
included in calculating the success rate.
3.1. Physiologic aging
The clinician must be aware of the physical, metabolic, and
endocrine changes associated with aging and how these
changes may affect implant treatment [11]. The human
skeleton accumulates bone up to an age of approximately
30 years and then gradually starts to lose bone [16].In
Table 1 Studies reporting implant failure rate compared between in young and old patients.
Authors Published
year
Observed
period (years)
Age group
(years)
Sample size
(persons)
Failure rate Statistical
significance
Remarks
Bryant and Zarb 1998 5—25 months 26—49 43 13.5 P>0.05 Same clinic
60—74 39 8
Brocard et al. 2000 7 <40 17.5 P<0.02 Multicenter
40—60 440 11.4
60<21.9
Engfors et al. 2004 5 <79 115 Maxilla: 7.0,
mandible: 0.5
P>0.05 Edentulous
patients
80 133 Maxilla: 7.4,
mandible: 0.3
Same clinic
Moy et al. 2005 Up to 20 <40 181 8.8 P<0.05 Same surgeon
40—59 418 13.3
60—79 499 17.9
79<42 16.7
Noguerol et al 2006 10 <40 117 4.3 P<0.05 Same clinic
41—50 347 6.3
51—60 357 7.0
60<263 1.1
Kinsel and Liss 2007 2—10 59 12 4.9 P>0.05 Edentulous patients
60<31 4.4 Immediate loading
Same surgeon
60 K. Ikebe et al.

general, human bone mineral density (BMD) reaches a peak at
age 25—30 years [17]. With increasing age, bones become
weaker as a consequence of a reduced amount of bone tissue
[18]. Age-associated bone loss is linked with an uncoupling of
osteoblastic and osteoclastic activity in favor of osteoclasis
[18]. Reduced estrogen bioavailability is the only indepen-
dent predictor of bone mass in both men and women [19].
For women, menopause is associated with decreased
estrogen levels, which in turn lead to increased bone resorp-
tion. The third National Health and Nutrition Examination
Survey (NHANES III, 1988—1994) of the USA indicated that
during the decade from 50 to 60 years, women lost about 10%
of their hip BMD, compared to only 2% for men [20]. After age
70, men start to lose BMD at a similar rate to women. Two
distinct syndromes of involutional osteoporosis were distin-
guished [21]: Type I or ‘‘postmenopausal’’ osteoporosis, in
which a loss of trabecular bone is predominant, resulting
mainly in fractures of the vertebrae and wrist, and Type II or
‘‘senile’’ osteoporosis, in which both cortical and cancellous
bone are lost, resulting in hip fractures as well.
Clinical studies in humans showed a delayed course of
bone healing with increasing age [22]. A reduced number of
osteogenic stem cells, their reduced proliferation and differ-
entiation potential, and reduced systemic or local blood flow
have been discussed as reasons for this [23]. The time
required for radiographic union following fracture increases
with age in humans [24—26]. While young 6-week-old rats
form bone to bridge the fracture gap by 4 weeks after
fracture, adult 26-week-old rats require 10 weeks, and older
52-week-old rats need in excess of 26 weeks [27].
With respect to the effects of increased age on period-
ontal tissues, histological findings such as the following have
been reported: thinning and diminished keratinization of the
epithelium; decreased cell density and synthesized collagen
in periodontal ligaments; and a decreased number of cells on
the osteogenic layer of the alveolar bone [28]. There are
‘‘natural delays’’ in the healing of older individuals. Open
wounds contract more slowly and incised wounds gain
strength more slowly. Experimental studies indicate that
cellular proliferation, wound metabolism, and collagen
remodeling occur later in older animals. Clinical studies
show, however, that operations can be performed safely in
elderly patients and that the major increased risk to these
patients is of non-wound medical complications that affect
the wound [29]. The ‘‘normal’’ incisional wounds healed
equally well in both groups. On the other hand, the ischemic
wounds in the old animals were found to be impaired by 40—
65% compared to similar wounds in the young animals [30].
Benatti et al. [28] showed that at 3 weeks, aging negatively
influenced density of newly formed bone and percentage of
bone fill in created fenestration defects of rats. At 6 weeks,
aging also negatively influenced density of newly formed
bone, but not percentage of bone fill. They concluded that
aging may impair, but not prevent, periodontal healing.
All of those findings seem to indicate that aging affects the
success of dental implants.
3.2. Pathologic aging
3.2.1. Diabetes
Diabetes mellitus is a significant disorder seen all around the
world. The prevalence of diabetic patients increases with
advancing age, especially in those over 50 and it was three
times greater in females than in males, according to a USA
study, The Third National Health and Nutrition Examination
Survey, 1988—1994 [31].
Diabetic patients show delayed wound healing, frequency
of microvascular disease, impaired response to infection, and
susceptibility to periodontal disease [32], all potentially
complicating factors when placing implants. Also, bone
and mineral metabolism are altered in diabetics [33], pos-
sibly interfering with the integration process [3,32].
Fiorellini et al. [33] in a study of 40 patients found the
survival rate of dental implants in controlled diabetic
patients at approximately 85%. This was lower than that
documented for the general population, but there was still
a reasonable success rate. Morris et al. [34] found in a large
sample population that Type 2 diabetic patients tended to
have more failures than non-diabetic patients; however, the
influence was marginally significant. In addition, Kapur et al.
[35] compared diabetics who had only moderate levels of
metabolic control with non-diabetic patients and also con-
cluded that implants could be used successfully in diabetic
patients.
Moy et al. [6] indicated that even patients with controlled
diabetes were almost three times as likely to develop
implant failure when compared to other patients. Interest-
ingly, Olson et al. [32] found that the implant survival rate
was relatively low in patients with Type 2 diabetes, and
duration of diabetes had an effect on implant success.
Greater failure rates were found in patients who had dia-
betes for longer time periods. The authors theorized that
just as with the increased likelihood of other microvascular
complications, an increasing duration of diabetes could
cause microvascular disturbances that might contribute to
implant complications. Therefore, older patients who have
been diabetic for a longer time are likely to be affected by
implant failure.
Klokkevold and Han [36] concluded in a systematic review
that Type 2 diabetes may have a negative effect on implant
survival, but the limited number of studies available for
review makes this conclusion tentative. In addition, since
the diabetic condition of patients in previous studies was
under control, no comment can be made about implant
survival in patients with uncontrolled diabetes.
3.2.2. Osteoporosis and estrogen status
Osteoporosis is the loss of bone mass and density throughout
the body, including the jaws [37]. Decreased bone mass in
postmenopausal women was reported to involve the alveolar
ridges, similar to other bones in the body [38]. However,
Boyde and Kingsmill [39] stated that common generalizations
about the changes in bone due to aging and osteoporosis are
too simplified, and that the mandible differs sufficiently from
postcranial skeletal sites so that it would be unwise to
extrapolate from findings in the jaw to circumstances else-
where. It is not certain whether bone mass in the mandible
and maxilla parallels bone mass in the rest of the skeleton,
although it has been shown that mandibular bone mineral
content decreases with age and that mandibular bone mass is
lower in elderly female subjects than in male subjects [16].
Slagter et al. [40] found no association between systemic
BMD status, mandibular BMD status, bone quality, and implant
loss. Bone metabolism is impaired and thus, theoretically,
Is old age a risk factor for dental implants? 61

osseous integration may be more difficult to achieve in osteo-
porotic patients; however, established systemic osteoporosis
does not imply that a jaw bone is unsuitable for osseous
integration, nor is it an absolute contraindication to implant
therapy [3]. Becker et al. [41] quantitatively measured osteo-
porotic bone loss in a group of dental implant patients and
found that a simple visual assessment of bone quality at the
site of implant placement may be more informative regarding
implant failure than quantitatively measured osteoporotic
bone loss. No correlation was found between the quantity
of arm bone and implant failures [40]. Osteoporosis frequently
occurs in postmenopausal women, but Dao et al. [9], in study-
ing the association between premenopausal and postmeno-
pausal women and implant failure, did notfind a higher failure
rate for implants placed in women older than 50 years as
compared with women younger than 50 years or between
women and men older than 50 years. Minsk and Polson [42]
also found no correlation in older women with or without
hormonal replacement therapy and implant failures.
None of the aforementioned studies differentiated
between maxillary and mandibular implants. August et al.
[15] examined jaw differences in pre- and postmenopausal
women and found that the effect of postmenopausal estro-
gen status on compromised implant healing was shown in the
maxilla but not in the mandible. The authors found that
postmenopausal women not taking hormone replacements
had the highest failure rate. Although a statistical difference
was not achieved, estrogen replacement therapy reduced
the maxillary failure rate by 41%. The authors reasoned that
because osteoporosis affects trabecular bone more than
cortical bone, and the maxilla has more trabecular bone
composition than the mandible, the maxilla is therefore more
susceptible to the effects of systemic osteoporosis.
It was reported that patients managed by surgeons who
have done more of knee and hip replacement have lower risks
of perioperative adverse events [43,44]. Moy et al. [6],ina
retrospective cohort study on implants done by one very
experienced oral and maxillofacial surgeon, evaluated sys-
temic osteoporosis and its effect on implant failure. The
authors showed that patients who were postmenopausal
and hormone replacement therapy experienced signifi-
cantly increased implant failure. The authors showed
that postmenopausal patients who were taking hormone
replacement therapy experienced significantly increased
implant failure.
4. Quality and quantity of available bone
Bone quality is related to osseointegration, and bone quan-
tity is related to the length of the implant, which is important
for initial stability and longitudinal success [45,46]. As stated
previously, both quality and quantity are theoretically
affected by aging.
Subsequent histomorphometric and microradiographic
studies showed that after the age of 50 there was a marked
increase in the cortical porosity of the mandible, with this
increase being greater in the alveolar bone than the man-
dibular body. With this increase in porosity, there was a
concomitant decrease in bone mass, which appeared to be
more pronounced in females than in males, with the loss in
bone mineral content estimated to be 1.5% per year in
females and 0.9% in males. These studies also demonstrated
a considerable amount of variation in the amounts of cortical
and trabecular bone within and among individuals [47].
Significant or strongly significant differences were found
regarding implant failures as a result of jaw bone quality, jaw
shape, implant length, treatment protocol, and combina-
tions of jaw bone-related characteristics [45]. Approximately
65% of the patients with a combination of the two most
negative bone-related factors (jaw bone quality 4 and jaw
shape D or E) experienced implant failure. Implant length,
the only implant-related factor evaluated, was also signifi-
cantly correlated with the success rate, but implant length
could also be regarded as a result of the jaw bone volume
available. In most cases this was also indirectly or partly
related to the status of the jaw bone available for implant
placement [45].
Morphologically, bone resorption of the labial or buccal
ridge makes prosthetic treatment much more difficult. Hor-
izontal discrepancies between the residual ridge of one jaw
for implantation and the residual teeth or ridge of the other
jaw are common. It is not an age-specific phenomenon, but
occurs frequently in the elderly. Bone quality is of concern
for implant success. To improve our understanding of how
the site-specificity of jaw bone condition affects oral
implant outcomes, research needs to be aimed at establish-
ing reliable and valid measures of preoperative jaw bone
condition, and at better documenting the effects of jaw
bone condition on oral implant outcomes [48].Objective
evaluation of bone quality and quantity with a CT (3-dimen-
sional shape and bone mineral density of local bone), which
has not been established will be important for successful
dental treatment [45].
5. Adaptation and maintenance
As with other prosthetic treatments, adaptation to the pros-
thesis and the ability to maintain it, including having access
to a dental office, are important with dental implant
patients. More problems with adaptation in the elderly
patients could be observed. Elderly patients especially had
more postinstertion problems than those in younger age
groups. Jemt [49] followed 48 patients more than 80 years
old (mean age 82.7 years) who had received a total of 254
implants and found that most had minimal postplacement
problems, similar to what has been observed in younger
patients. However, some patients (10%) experienced obvious
problems with general adaptation and muscle control, which
has not been observed in younger patients. Oral hygiene
problems and associated soft tissue inflammation (mucositis)
as well as tongue, lip, and cheek biting were observed
significantly more often among the elderly patients [7].
6. Problems and limitations in clinical
studies
Study design remains important. Retrospective cohort stu-
dies are easier to complete but due to problems of selection
bias and confounding have less validity than randomized
prospective clinical trials. The conclusions that can be drawn
from retrospective studies may be limited [50]. In such
studies, successful patients and treatment plans tend to
be influenced by ethical considerations so that success rates
62 K. Ikebe et al.

must be relatively high, whether subjects are young or old,
healthy or compromised. We have to realize that if study
samples include all applicants for implant treatment, the
success rate for older patients must be lower than that for
younger ones. Interestingly, Noguerol et al. [46] showed that
in the multiple logistic model, younger age (odds ratio: 4.53),
as well as smoking habits (OR: 2.59), and bone quality (OR:
1.93) were independently related to early failure. This effect
is odd and may be caused by a selection bias, where those
over the age of 60 would only be treated with implants under
‘ideal’ conditions or might, as past users of removable
prostheses, value and take greater care of their new fixed
prostheses.
Clinicians need the results of randomized, controlled
clinical trials for evidence-based decision making. However,
these types of studies are difficult to design and are time-
consuming, expensive and possibly unethical [3].
7. Conclusion
In dental implant treatment, chronological age by itself is
suggested as one of the risk factors for success, but it would
not be a contraindication. In general, reserved capacity of
bone and soft tissue make it possible to establish osseointe-
gration in the long run. Rather than aging itself, the specific
nature of the disease process, such as osteoporosis or dia-
betes, and local bone quality and quantity at the implant
site, mostly related to aging, are more important for success-
ful dental implant treatment.
This review revealed a shortage of published data for the
survival and success of dental implants in older patients.
More studies useful for evidence-based decision making are
needed to assess the survival and success of dental implants
for aged patients with a compromised condition. Long-term
studies are expected to be more revealing of the influence of
risk factors related to aging.
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