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A SYSTEMATIC REVIEW AND META-ANALYSIS OF DENTAL IMPLANTS IN
PATIENTS WITH DIABETES MELLITUS
Saparbayev Zakir Jumanazarovich
Assistant at the Alfraganus University
Email: saparbayevzokir163@gmail.com
https://doi.org/10.5281/zenodo.14016021
Abstract
This review aimed to assess the effects of diabetes mellitus on dental implant failure
rates and marginal bone loss (MBL). An electronic search was conducted across three
databases, supplemented by a manual search of relevant journals. Meta-analyses and meta-
regressions were performed to examine how the odds ratio (OR) and MBL were influenced by
follow-up duration. A total of 89 studies were included in the review, encompassing 5,510
implants in diabetic patients and 62,780 in non-diabetic patients. Pairwise meta-analysis
revealed a higher failure risk for implants in diabetic patients compared to non-diabetic
patients (OR 1.777, p < 0.001). Implant failure was significantly more frequent in type 1
diabetes patients than in type 2 (OR 4.477, p = 0.032). Statistically significant differences in
implant failure rates were observed between the maxilla and mandible, with significance only
in the maxilla. The mean difference (MD) in MBL between diabetic and non-diabetic patients
was 0.776 mm (p = 0.027), with an estimated MBL MD increase of 0.032 mm per additional
month of follow-up (p < 0.001). Additionally, there was an estimated OR decrease of 0.007 for
each extra month of follow-up (p = 0.048). In conclusion, dental implants in diabetic patients
showed a 77.7% higher failure risk compared to those in non-diabetic patients.
Keywords:
dental implant, implant failure, marginal bone loss, diabetes mellitus,
systematic review, meta-analysis, meta-regression.
1. Introduction
Diabetes mellitus encompasses a group of metabolic disorders marked by elevated
blood glucose levels, which arise from problems in insulin production (when the pancreas
does not release enough insulin), insulin function (when the div cannot effectively utilize the
insulin produced), or both. The most common form, type 2 diabetes, represents the vast
majority of cases worldwide, and its prevalence has been rapidly increasing, with predictions
indicating a significant rise in affected adults over the coming years. This highlights the critical
importance of understanding the impacts of diabetes.
Chronic high blood sugar levels in diabetes often lead to damage, dysfunction, or even
failure of various tissues and organs, resulting in significant health burdens. Additionally, the
duration of diabetes itself can influence a patient’s clinical and functional condition,
regardless of glycemic control or age. These complications stem from several adverse effects,
such as delayed wound healing, microvascular issues, reduced infection response, and
compromised bone metabolism and strength. For individuals who develop type 2 diabetes at
a young age, the risk of these complications steadily increases over time, affecting many by
early adulthood.
Blood sugar levels, or glycemia, play an important role in these outcomes, as research
has shown a connection between glycemic control and the development of complications
affecting both small and large blood vessels. Intensive glycemic control in diabetic patients
can delay the onset and progression of various complications linked to microvascular damage,
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although this benefit tends to diminish once complications have already manifested. Diabetic
patients are considered to have controlled diabetes when their blood glucose levels are kept
close to normal, typically indicated by the HbA1c test, which measures the percentage of
glycated hemoglobin. Patients with HbA1c levels up to a certain threshold are considered
well-controlled.
The negative impact of diabetes on bone metabolism has led to concerns about the long-
term success of dental implants in diabetic patients. A prior systematic review on this topic
has provided some insight, suggesting that diabetes may indeed affect implant failure rates
compared to non-diabetic patients. However, that earlier review included only a limited
number of studies. Therefore, the goal of this current systematic review is to expand on
previous findings, comparing implant failure rates and marginal bone loss between diabetic
and non-diabetic patients on a larger scale.
2. Materials and Methods
This study adhered to the guidelines set forth by the PRISMA 2020 Statement and was
registered in the PROSPERO database (CRD42021240670).
2.1. Objective
The aim of this study was to evaluate the null hypothesis that no difference exists in
implant failure rates and marginal bone loss (MBL) following the placement of dental
implants in diabetic patients compared to non-diabetic patients, contrasting this with the
alternative hypothesis that a difference does exist. This investigation was conducted through
a systematic review of the literature.
To guide the study, the PICO framework (participants, interventions, comparisons,
outcomes) was used to formulate the focused question: Among partially and fully edentulous
patients (participants) receiving dental implants (intervention), is there a difference in
implant failure rates and MBL (outcomes) between diabetic and non-diabetic patients
(comparison)?
2.2. Search Strategies
An electronic search without date restrictions was conducted, with the final update
completed in October 2023, across the following databases: PubMed/Medline, Web of Science,
and Scopus. The search terms used were: (“dental implant” OR “oral implant”) AND (diabetes
OR diabetic)
A manual search of journals related to dental implants (listed in the Supplementary
Material) was also performed. Additionally, the reference lists of identified studies and
pertinent reviews on this topic were reviewed for any additional relevant studies.
2.3. Inclusion and Exclusion Criteria
Included in this review were clinical studies in humans that provided data on implant
failure rates for diabetic and non-diabetic patients treated with cylindrical, modern dental
implants made from commercially pure titanium or its alloys. Since an individual cannot be
randomized as diabetic or non-diabetic, non-randomized and retrospective clinical studies
were also considered for inclusion.
Only studies involving diabetic patients under glycemic control were included. If
glycemic control information was not available in the publication, it was obtained by
contacting the study authors directly.
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Excluded from this review were case reports, technical reports, animal studies, in vitro
studies, and review papers. Additionally, studies focusing on mini-implants, zygomatic,
orthodontic, zirconia, subperiosteal, or hollow implants were excluded.
3. Results
Detailed information on the 89 studies included, published between 2001 and 2023.
These studies were primarily conducted at a single center (n = 73) or across multiple centers
(n = 16). The studies comprised eight randomized clinical trials (RCTs), 11 prospective
studies (without a pre-established control group), 15 prospective controlled clinical trials,
and 55 retrospective observational studies. The countries with the highest frequency of
studies included the USA (n = 19), Italy (n = 13), Spain (n = 6), and Brazil, Germany, and
Belgium (five studies each), along with Austria, Portugal, and South Korea (four studies each),
and Sweden (n = 3), among others.
The average follow-up period (± standard deviation) for 72 studies was 38.8 ± 35.0
months, with a range from 3 to 194.3 months. Precise follow-up details were not available for
the remaining 17 studies, which provided information like “patients were followed between
2006 and 2009” or “up to 48 months.”
The studies employed various loading protocols, with delayed loading being the most
frequent (43 studies), followed by immediate loading (34 studies), early loading (4 studies),
and no prosthetic loading (4 studies). This information was not reported in 23 studies. Some
studies applied a single loading protocol for all implants, while others used a combination for
different implants within the same study.
Among the studies, 63 included implants in both jaws, 13 focused only on maxillary
implants, and 13 on mandibular implants. Eight studies specifically excluded smokers, and six
did not provide information on smoking status within the patient cohort.
In total, 5,510 implants were placed in diabetic patients (with 394 failures), and 62,780
implants in non-diabetic patients (with 2,343 failures). The most frequently used implant
brands were Nobel Biocare (Göteborg, Sweden) in 39 studies, Straumann (Basel, Switzerland)
in 20 studies, and Astra Tech (Mölndal, Sweden) in 11 studies. The implant brand and/or
system used was not specified in 12 studies.
A comparison of mean marginal bone loss (MBL) between diabetic and non-diabetic
patients was available in 10 studies, of which nine also provided the standard deviation,
necessary for conducting a meta-analysis of continuous variables.
4. Discussion
This systematic review aimed to compare clinical outcomes of dental implants in
diabetic versus non-diabetic patients. While previous reviews have addressed this topic, they
either did not include statistical analysis or were limited by a smaller number of clinical
studies. This review, incorporating data from 89 studies, provides a broader scope and is the
first to introduce several analyses: (a) a sub-analysis comparing implant failure rates between
type 1 and type 2 diabetic patients; (b) subgroup analyses focusing separately on implants
placed in maxillae and mandibles; (c) a meta-regression assessing the association between
implant failure odds ratios for diabetic and non-diabetic individuals and follow-up duration;
(d) a meta-analysis comparing MBL between diabetic and non-diabetic patients; and (e) a
meta-regression examining the relationship between follow-up duration and MBL differences
between diabetic and non-diabetic patients.
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The findings from this review indicate that diabetic patients experience a significantly
higher risk of dental implant failure and greater marginal bone loss compared to non-diabetic
patients, leading to the rejection of the null hypothesis. These outcomes are largely attributed
to the adverse effects of diabetes mellitus on various physiological processes in the div.
Diabetes mellitus negatively impacts bone metabolism and bone strength.
Hyperglycemia, commonly resulting from inadequate glycemic control, can lower bone
mineral density (BMD) and increase fracture risk by raising urinary calcium excretion and
accumulating advanced glycation end products. This accumulation promotes inflammation,
decreases insulin-like growth factor 1 (IGF-1) levels, and creates a more acidic environment.
IGF-1 plays a crucial role by enhancing bone matrix synthesis, promoting bone formation, and
regulating osteoclastogenesis, which helps with bone resorption and remodeling. Clinical
studies have shown that patients with type 1 diabetes have lower total div BMD compared
to matched non-diabetic individuals.
Another complication of diabetes is delayed wound and bone healing. Dental implant
placement involves controlled surgical intervention in the bone, which initiates healing
processes beginning with blood clot formation, vascularization, and the migration of
mesenchymal stem cells (MSCs) from surrounding bone marrow. Under optimal conditions,
MSCs differentiate into osteoblasts, leading to the formation of woven bone, which later
compacts and remodels into mature bone. However, in diabetic patients, compromised bone
cell metabolism and alterations in bone matrix properties hinder bone healing, reducing
matrix strength and potentially jeopardizing implant osseointegration.
Conclusions
In summary, dental implants in diabetic patients exhibit a statistically significant higher
risk of failure and increased marginal bone loss compared to implants in non-diabetic
patients. Additionally, when comparing different types of diabetes mellitus, implants in
patients with type I diabetes have a substantially higher risk of failure than those in patients
with type II diabetes.
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