REVIEWSCIENTIFIC
ARTICLES
Stomatologija, Baltic Dental and Maxillofacial Journal, 19: 10-8, 2017

Surgery-related factors affecting the stability oforthodontic mini implants screwed in alveolar processinterdental spaces: a systematic literature review
Greta Gintautaitė1, Alė Gaidytė2

SUMMARY
The ambiguous results of scientific researches on surgical factors affecting the stability ofmini implants (MI) impels the physicians to constantly analyze this problem. The objective of
this article was to conduct a systematic literature review about surgery related factors affecting
the stability of MI screwed in alveolar process buccal surface between the second premolar andfirst molar roots based on peer reviewed publications of 2009-2015.
The Cochrane and PRISMA references were used while searching for scientific literature.
Two data bases and scientific publications were browsed in the Lithuanian University of Health
Sciences library. Criteria for article selection were: 1) research in which surgical factors affecting MI stability were analyzed, 2) research in which stability of MI screwed in alveolar process
between adjacent teeth roots was analyzed, 3) research in which MI stability was analyzed inclinical practice, 4) articles which were published in 2009-2015. Selected articles were evaluatedin accordance with methodical quality.
13 articles met the selection criteria of the research. 2652 MI screwed in 1205 people jawbones’ alveolar processes were analyzed in selected articles. The MI success rate was 87.7-97%.
Root proximity was identified to be the main determinant of all MI success influencing surgicalfactors (MI and root contact determined a 9-26.7% failure rate). The results of this article confirm
the sufficient MI stability rate in clinical practice and specifies root proximity as the main surgicalfactor affecting the MI stability.
Key words: mini-implant, temporary anchorage device, stability, success, failure.
INTRODUCTION
Various temporary skeletal anchorage devices
have been successfully used in orthodontics fortwo decades (1). Smaller than 2.0 mm in diametermini implants (MI) are one of the most popular
temporary anchorage devices used in orthodontics (2). In comparison to other skeletal anchorage
methods, MI have been recognized to be especiallyeffective, as their success rate is averagely 90%(1-13). The advantages of MI are various jawbone
locations where they can be screwed in, the decreased necessity of patient’s collaboration during
treatment, lower negative effect on teeth, price,minimal surgical intervention, practitioner’s andpatient’s comfort and clinical efficiency (14, 15).

Address correspondence to Greta Gintautaitė, UAB Ortokoncepcija,
Archyvo 13, Kaunas, Lithuania.
E-mail address: ggintautaite@gmail.com

Due to MI anchorage the orthodontist can preserve
up to 2.4 mm more space in dental arches than withother traditional anchorage devices (16, 17). These
are the reasons why MI are widely used in difficult
orthodontic situations for asymmetric treatment
in all three dimensions and as an alternative fororthognathic surgery (18).
The most popular MI insertion sites are theinterdental spaces between the first molar andsecond premolar roots (19-24). Rodriguez et al. (2)specify the success rate of such MI to be 87.8%
and the majority of failures is related to surgicalprocedures (78.45%) and orthodontic treatment(19.83%). On the other hand, based on recent decadescientific researches, MI stability is determined byvarious factors acting simultaneously, therefore itis difficult to evaluate their individual influence on
MI stability (21, 25-30). Three main groups of MI
stability affecting factors have been established byvarious authors: 1) surgery-related, 2) orthodontic-

10

Stomatologija, Baltic Dental and Maxillofacial Journal, 2017, Vol. 19, No. 1

UAB Ortokoncepcija, Kaunas, Lithuania
Clinic of Orthodontics, Lithuanian University of Health Sciences,
Kaunas, Lithuania

1
2

REVIEW

G. Gintautaitė1, A. Gaidytė
M ATER I A L
AND METHODS

related, 3) patient-related factors. Due to the latest
systematic literature reviews and meta-analyses,
surgery related factors have the main impact on
MI stability (success, failure) (1, 2, 31, 32). This
group of factors include the shape, type, construction, diameter, length and surface manufacturingof MI, shape of the thread, MI insertion angle andtorque, type of implantation, experience of practitioner, MI insertion site (maxilla or mandible,
which interdental space, the amount of cortical andtrabecular bone, type of soft tissue) and iatrogenic
complications. More and more scientific researches
about these MI stability affecting surgery related
factors have been published and their results aremostly contradictory. Therefore, the scientificsociety, practitioners and manufacturers are being
forced to seek for comprehensive and scientificallyreasoned researches, which would contribute intreatment planning and lower failure rates. Accordingly, the objective of this article was to conduct asystematic literature review about surgery related
factors affecting the stability of MI screwed inalveolar process buccal surface between the second premolar and first molar roots based on peer
reviewed publications of 2009-2015.

The Cochrane
Ha ndbook for Systematic Reviews ofInterventions and the
PR ISM A st atement
guidelines were usedas the framework forthis article. PubMed( Medli ne) a nd SciVer se (Science Direct) data bases werereviewed for articles
published in English
i n 20 0 9 -2015. T he
key words and their
combinations used forarticles’ search were:mini-implant, miniscrew, ortho-implant,
orthodontic anchoragescrew, temporary anchorage device, tempora r y skelet al anchorage device, orthodontics, mini implant,
mini screw, surgical,
stability, success, failure, rate, risk factors.
The article selection criteria were determinedaccording to the object of research, type and methodof study, sample size and analysis of the results:
1. Articles analyzing the influence of surgery
related factors on the stability of MI screwed
in alveolar process interdental spaces;
2. Research on MI stability during orthodontic
treatment;
3. Sample size ≥40 MI;
4. The MI diameter ≤2.0 mm;
5. Researches of MI which were used as ananchorage for ≥12 weeks or until the orthodontic treatment ending;
6. Articles published in English in peer reviewed journals in 2009-2015;
7. No sex or age restrictions.
Articles exclusion criteria were:
1. Single clinical case reports;
2. In vitro studies;
3. Finite element analysis studies;
4. Animal studies;
5. Review articles.
All titles and summaries of found publications
were reviewed in order to exclude all inadequate

Stomatologija, Baltic Dental and Maxillofacial Journal, 2017, Vol. 19, No. 1

11

Fig. 1. The PRISMA Flow Diagram

G. Gintautaitė1, A. Gaidytė

REVIEW

rejected because of repeating in the databases. The
articles. The full versions of remaining, possibly apremaining 1174 articles’ summaries were analyzed
propriate, articles were reviewed. The full texts ofin detail. The articles which had not conformed thearticles’, which eligibility could not be evaluated byinclusion requirements were rejected and 43 articles’
reviewing their summaries, were read on purpose to
full texts were downloaded and read. After applying
avoid incorrect exclusion. The process of articles’ sethe inclusion and exclusion criteria only 13 articles
lection is presented in the PRISMA diagram (Figure 1).
were left. These articles were evaluated qualitatively.
All inclusion criteria matching articles wereanalyzed and their qualit y wasevaluated based on modified Feld- Table 1. The criteria of articles’ qualitative evaluationmann and Bondemark (33) suggested Analyzed Description
Evaluation
method under five criteria: 1) sample criteriasize, 2) research method, 3) research Sample size The quantity of analyzed MI 0-10 – 0 points;
object description, 4) research tech11-20 – 1 point;≥21 – 2 pointsnique and 5) study design (Table 1).
Research method used for MI None – 0 points;
After qualitatively evaluating all Researchinsertion site analysis
Radiological 2D – 1 point;
articles, they were divided into two method
Radiological 3D, histologicalcategories: of high (8-10 points) (3-9,
analysis or scanning electron
11, 34-36) and medium (6-7 points)
microscopy – 2 points(10, 12) quality.
Research
objectdescription
Researchtechnique

RESULTS AND DISCUSSION
1797 articles were found after
primary electronic databases search.
The search results are shown in
the PRISMA articles’ search flow
diagram (Figure 1). 623 articles wereStudy
designThe quantity of researchedindividuals

0-5 – 0 points;
6-10 – 1 point;≥11 – 2 points
Clinical examination, the use Clinical examination – 1 point;of objective measuring device The use of objective measur(Periotest, torque screwdriver, ing device – 2 points
orthodontic tension gauge)
Controlled, uncontrolled study Uncontrolled study – 1 point;
controlled study – 2 points

Table 2. Analyzed researches’ results
ArticleDiameter(mm)

Shigeeda (3)Min et al. (4)Length PaPatients’MI sample,(MM) tients average
self-tapping
sample age (years) (ST)/selfdrilling (SD)1.6
85824.4±8.5
165, ST
1.2-1.3 8
94
19.36±5.66 172, SD

The
numberof failures
8
16

95
90.7

≥6
12, or until orthodontic treatment end

Jung et al. (5)1.2-1.3 813019.24±6.66 228 SD

28

87.7

Shinohara et al. (6)

1.6

50

21.8±5.7

147, ST8

94.6

12, or until orthodontic treatment end≥3

Manni et al. (7)1.3; 1.5 9;11132300, ST

57

81

11.63

Lai et al. (8)

1.6-2

8-10

129

Women
25.9±11.6;
men
19.6±10.1
20.2±9.4

266, n/d

8

97

≥3

8

8

Success MI loading duration
rate, % (months)

Sharma et al. (9)

1.3

73

22.45±6139, n/d

1787,88.96±4.8

Lim et al. (10)1.6; 1.8 6-8;10168

23±8.7407, n/d

28

93,1

≥3

Janson et al. (11)

1.5

7

21

16.99±5.08 40, SD

4909.22±3.12

Wu et al. (12)1.2-226.5±8.9414, SD

42

89,9

≥6

Watanabe et al. (34)1.4

7;8;10- 166
12
5;6;8
107

21

190, ST

N/d

N/d

≥3

8

52

26.1±8.4

134, ST

N/d

N/d

8.5

25

26

50 ST

N/d

N/d

12, or until orthodontic treatment end
15.3

Motoyoshi et al. (35) 1.6
Kim et al. (36)

12

1.8

Stomatologija, Baltic Dental and Maxillofacial Journal, 2017, Vol. 19, No. 1

REVIEW

G. Gintautaitė1, A. Gaidytė

The randomized controlled trials of MI usedduring orthodontic treatment were analyzed in all
13 publications. MI of 9 different manufacturers
and 2 types (self-tapping and self-drilling) whichwere threaded in 1205 patients’ upper and lower
jaws’ alveolar process buccal surface between rootsof the first molar and second premolar were analyzed. 2652 MI 1.2-2.0 mm in diameter and 5.0-12.0
mm in length were analyzed. Based on the resultsof ten articles’ (3-12) in which failure of MI was
studied, 216 (9.48%) from 2278 MI were unsuccessful (Table 2).
The sample of analyzed MI was more than 100
MI in the majority of articles (3-10, 12, 34, 35) andonly in two articles less MI were used (40 and 50
MI) (11, 36). The number of patients included into
researches was 21-168. The analyzed MI were used
for anchorage for at least 3 months.
The MI stability/success/failure affecting factors were analyzed in all articles, however, not all
authors had given the defi nition of a “successful”
MI (Table 3). The „success“ was described onlyin six articles (3-5, 7, 9, 12). On the basis of given
descriptions, a successful MI is that which performs
its’ function of a temporal skeletal anchorage device for a certain period of time (6-12 months) or
during all orthodontic treatment and any notable orprogressive mobility and no surrounding soft tissue
inflammation or other pathologies are found.
The analyzed surgery related factors affecting
MI stability were: jaw (maxilla, mandible) (6-10,
12, 34, 35), side of MI insertion (left, right) (4, 5,
7-9, 12), cortical bone thickness and bone density(4, 5, 8, 34, 35), type of soft tissue (keratinized,
non-keratinized, mucogingival junction) (7-11), insertion angle in vertical and horizontal planes (5, 6,
34, 36) and insertion torque (35, 36), MI proximity
to adjacent roots (3-7, 11, 34, 36) and practitioner’s
experience (10, 12) (Table 3).
None of the authors analyzed MI insertion site
diagnostics and clinical selection criteria in detail.
The importance of MI diameter selection for MI
stability was analyzed in only one article (12).
The authors specified that MI of 1.4 mm diameteror smaller in maxilla and MI wider than 1.4 mm
in mandible had statistically significantly higher
stability (Table 3). The authors have not found any
influence of MI length and type on success rate.
Different diagnostics methods were applied for
MI insertion site analysis in the researches. Only
clinical examination was applied in four researches(8-10, 12), radiological 2D examination was appliedin two researches (7, 11) and in the remaining sevenstudies radiological 3D – computed tomography orcone beam computed tomography (CBCT) wereapplied (3-6, 34-36) (Table 3). There were several
additional clinical examination methods appliedfor MI stability analysis in four articles (3, 11, 35,36): the Periotest device (Medizintechnik Gulden,
Bensheim, Germany), orthodontic tension gauge(Correx series 040-712-00, Dentaurum Orthodontics, Ispringen, Germany) and torque screwdriver(N2DPSK, Nakamura, Tokyo, Japan).
The success rate of MI was assessed in theanalyzed articles. On the basis of the researches’
results, the success rate of MI used during orthodontic treatment was from 87.7% to 97%, though
the success rate was not presented in two articles(34, 35). In seven articles the success rate of MI
was analyzed in maxilla and mandible (6-10, 12,34). The MI success rate in maxilla ranged from
86.9% to 97.2% and in mandible – from 70.69% to93.7%. In five researches (6-8, 12, 34) the successrate of MI was higher in maxilla than mandible; in
two articles – the results were the opposite (Table 3).
The influence of MI implantation site on successrate was analyzed in six researches (4, 5, 7-9, 12).
Even though the success rates on the left jaw side
were higher, but there had not been found any statistically significant difference between the jaw sides.
The authors of three researches (4, 5, 34) had
been analyzing the influence of cortical bone layer
on MI success rate. It was found out that the thickness of cortical bone is not the major factor influencing the stability of MI. Min et al. (4) declared thata 0.1-mm increase in the cortical bone thickness
increased the success rate only 0.366 times (P>0.05),
while based on Jung et al. (5), such cortical bone
thickening increased the success rate 32.2 times(P>0.05) (Table 3).
The inf luence of bone quality in MI insertion site on the MI success rate was analyzed by
Lai et al. (8). Based on the quality of bone classification by Lekholm and Zarb (37), Lai et al. (8)distinguished four categories: Q1 – bone in whichalmost the entire bone is composed of homogenous
compact bone, Q2 – bone in which a thick layer ofcompact bone surrounds a core of dense trabecularbone, Q3 – bone in which a thin layer of corticalbone surrounds a core of dense trabecular bone,
Q4 – bone characterized as a thin layer of corticalbone surrounding a core of low density trabecularbone of poor strength. On the basis of the research
results, a successful treatment with MI may be expected if the MI is threaded in a high quality bone
tissue: the MI success rates in Q1-Q3 groups were100%, 98.7% and 94.8% respectively, while in Q4
group – only 66.7% (Table 3). Watanabe et al. (34)

Stomatologija, Baltic Dental and Maxillofacial Journal, 2017, Vol. 19, No. 1

13

G. Gintautaitė1, A. Gaidytė

REVIEW

were analyzing the interface between bone density
and MI success rate and no statistically significant
difference was detected (Table 3).
The influence of MI proximity to adjacent teeth
roots on MI success rate was analyzed in eightresearches (3-7, 11, 34, 36). The results of all theseresearches declare the statistically significant dif-ference between successful and unsuccessful MIgroups: MI without contacts with adjacent teeth
roots had higher success rates (Table 3). Three researches’ authors emphasized the MI proximity to
adjacent roots as the major MI success rate affecting
factor (5, 11, 36). Watanabe et al. (34) classified theperiapical radiographs into four groups (A-D) in

Table 2. Analyzed researches’ results (continued on next page)
ArticleShigeeda(3)„Successful MI“ definition description
A stable MI whichwithstands orthodontic
loading for ≥6 months
with no mobility

Diagnostics
method
CBCT; Periotest

Results

Failure rate without/with MI contact with dental root in maxilla: 1.7%/10.5%; in mandible: 1.4%/25.0%. Periotest value inmaxilla: A* – 1.4±3.7, B – 1.6±2.1, C** – 1.5±2.5; in mandible:
A* – 2.9±2.6, B – 3.2±2.2, C** – 5.6±3.8 (*, **: P<0.05). MI
screwed in mandible had a higher mobility than in maxilla.
16/172 (9.3%) MI had contacts with dental roots. 11/16
Min et al. MI remained in bone and CBCT
was an appropriate skel(68.8%) of MI with dental roots contacts were unsuccess(4)etal anchorage for 1 year
ful. A 0.1-mm increase in MI proximity to dental roots andof orthodontic treatment
cortical bone thickness increased the success rate 69.6448
times (P<0.05) and 0.3660 times (P>0.05) respectively. The
MI proximity to dental roots had a higher influence on the increase of success rate. Increasing the MI proximity to adjacentdental roots, the success rate is increasing statistically significantly.
The average vertical and horizontal MI insertion angle, MI
Jung et al. MI remained in bone and CBCT
was an appropriate skelproximity to adjacent roots and cortical bone thickness in suc(5)etal anchorage for 1 year
cess and failure groups were: 73.75° and 75.93°; 97.11° andof orthodontic treatment
96.65°; 0.49 mm and 0.11 mm; 1.17 mm and 0.97 mm respectively. A 0.1-mm increase in MI proximity to dental roots andcortical bone thickness increased the success rate 25.27 times(P<0.05) and 32.2 times (P>0.05) respectively. MI success affecting factors in a descending order: MI proximity to adjacentroots, cortical bone thickness, insertion angle in horizontal andvertical planes.
Shinohara N/d
CBCT
Averagely 20% of MI had contacts with dental roots. The
et al. (6)average MI proximity to dental roots was 0.6-1.0 mm. The average vertical MI leaning in maxilla: 48.3°-50.4°; in mandible:
57.5°-63.3°. A statistically significantly higher rate of MI contacts to adjacent distal teeth were identified in the right side ofmaxilla. 2 MI of 118 with no contacts with adjacent roots were
unsuccessful (1.7%). 6/29 MI with contacts to adjacent roots
were unsuccessful (20.7%).
57 MI were unsuccessful (19%). 35 MI (61.4%) were removed
Manni et Any surrounding soft tis- Radiologicalsue inflammation or MI 2D
due to mobility; 4 (7.1%) – due to acute post-operative inflamal. (7)mobility is detectedmation; 18 (31.6%) – were lost itself. Lower diameter MI (1.3mm) had a statistically significantly higher success rate than
1.5 mm diameter MI (9 mm and 11 mm length): 88.3%, 75.5%
and 79.3% respectively. No statistically significant relations
between MI relation to adjacent root (coronal, middle or apicalthird) was detected.
Clinical exami- Analyzed MI diameter/length (mm): 1) 1.6/8.0, 2) 1.6/10.0,
Lai et al. N/dnation3) 2.0/10.0 (the success rates: 94.8%, 95.2% and 97.0%(8)respectively (P>0.05)). MI screwed in higher quality bone
tissue (Q1, Q2 and Q3) had statistically significantly higher
success rates than MI screwed in poor quality bone (Q4):
100%, 98.7%, 94.8% and 66.7% respectively. No statisticallysignificant relation between success and failure groups due to
MI diameter and length, patient’s sex and age, malocclusion
type and MI insertion side was detected.

14

Stomatologija, Baltic Dental and Maxillofacial Journal, 2017, Vol. 19, No. 1

REVIEW

G. Gintautaitė1, A. Gaidytė

their research according to the proximity of the MI
and the root (Figure 2). The authors had also done
the CBCT examination of the MI proximity to adjacent teeth roots. The CBCT radiographs had beenclassified into four types according to the proximity of MI’s three points (apex, middle and neck at
alveolar bone level) to the root: A – all three points>0.7 mm from the root surface, B – only the apex
point ≤0.7 mm from the root surface, C – only the
middle point ≤0.7 mm from the root surface, D – twopoints ≤0.7 mm from the root surface. The authors
had declared that it was difficult to differentiate theroot surface from the MI when the distance was ≤0.7
mm (Figure 3). The authors compared the MI suc-Table 2. Analyzed researches’ results (continued from previous page)
Article„Successful MI“ defini- Diagnostics
tion description
methodSharma et An unsuccessful MI: was Clinical examilost itself, a notable mo- national. (9)bility was observed and a
repeated MI insertion wasnecessary, or soft tissue
pathological changes orpain was identified
Clinical examiLim et al. N/dnation(10)

Results
MI survival period was 8.96±4.8 months. Poor oral hygiene,
MI insertion in mobile gingiva and MI surrounding soft tissue
inflammation lead to MI failure.

MI, which were screwed in by more experienced had a 7.1%
higher success rate (97.5%). No statistically significant difference between groups of patients’ sex and age, jaw, oral mucosa
type, MI length and diameter was detected. MI primary stability
depends on the insertion site and practitioner’s experience.
Bitewing radio- The analyzed MI were divided into two groups according to
Janson et N/dgraph; orthoseptum width: 1) ≤ 3mm (20 MI), 2) >3 mm (20 MI). The MI
al. (11)dontic tension proximity to dental roots was statistically significantly lower ingaugegroup 1. MI proximity to the root did not have any statisticallysignificant relation with the mobility degree. Although, due tothe minimal proximity between MI and the root the periodontal ligament can be damaged during MI insertion, which may
increase MI failure rate. The interdental septum width did nothave any influence on MI success rate. A small MI proximity to
the root had the major influence on MI success rate.
Wu et al. The MI which remained Clinical exami- The failure rate in maxilla/mandible when MI diameter ≤1.4
as an orthodontic anchor- nation
mm: 8.4%/16.3% (P=0,036); when MI diameter >1.4 mm:(12)
age for 6
13.2%/2.7% (P=0,085). No statistically significant association between the MI failure rate and patient’s age, sex and MI insertionsite was detected. The failure rate of the MI inserted by the samepractitioners decreased from 25% to 7.9% from 2002 to 2006.
Watanabe N/dPeriapicalThe success rates were measured after periapical radiographs’
et al. (34)radiographs;
analysis: A – 96.08%, B – 66.67%, C – 88.89%, D – 78.57%.
CBCT
The success rates were measured after CBCT radiographs
analysis: A – 94.5%, B – 62.5%, C – 50.0%, D – 14.29%. The
average MI insertion angle in maxilla and mandible were: 4243° and 45-57° respectively. No statistically significant association between MI insertion angle, bone density and success andfailure groups was detected.
Motoyoshi N/d
CBCT; Torque No statistically significant difference between MI insertion and
et al. (35)
screwdriver
removal torque due to cortical bone thickness was detected. A
statistically significant association between cortical bone thickness
and MI insertion torque in maxilla was detected (r=0.392, P<0.05).
CBCT; digital Based on MI proximity to dental roots or maxillary sinus penetraKim et al. N/dtorque screwtion, the groups of analyzed MI were: 1 – MI showed root prox(36)driverimity on one side, 2 – MI showed root proximity on both sides,
3 – MI had no root contact but penetrated the sinus, 4 – MI had
both root proximity and sinus penetration. The majority of MI
and root contacts was detected in group 1. Multiple MI contacts
with adjacent roots with maxillary sinus penetration and without
primary stability had the major impact on MI failure. MI andcontacting root surface area had impact on MI stability.

Stomatologija, Baltic Dental and Maxillofacial Journal, 2017, Vol. 19, No. 1

15

G. Gintautaitė1, A. Gaidytė

REVIEWcess rates in different
groups between analyzed periapical and
CBCT radiog raphs.
The success rate results of both analysis methods were thehighest in group A anddecreased in groups B,
C and D respectively.
The success rates werelower in CBCT radiographs group (Table3). Shigeeda (3) also
analyzed the CBCT A
B
C
D
radiographs to evaluate the influence of MI Fig. 2. Classification of the periapical radiographs from A to D according to the proximity of theproximity to adjacent mini-implant and the root: A – the mini-implant was completely separated from the root surface, B
apex of mini-implant was in contact with the root surface, C – the neck at alveolar bone level
teeth roots on MI suc- –oronly
middle part of the mini-implant was in contact, and the apex was separated from the root surface,cess rate (Figure 4). D – the entire body of the mini-implant was in contact with the root surface (Watanabe et al (34)).
The MI failure rates
in groups A-C were evaluated and the results were1.5%, 9% and 26.7% respectively. Consequently,
multiple MI and root surface contacts considerably
reduces the MI success rate (Table 3).
The influence of MI insertion angle on the success rate was analyzed in four researches (5, 6, 34,36). However, there was no statistically significant
association detected (Table 3).
The practitioner’s experience influence on MI
success rate was analyzed in two researches (10,12). Lim et al. (10) estimated the MI success rates
of practitioners with lower and higher MI insertion
experience (< 20 and ≥ 20 inserted MI respectively).
The results of MI success rate were 7.1% higher inmore experienced practitioners’ group (Table 3). Wu
et al. (12) also determined the association between
practitioner’s experience and MI failure rate, which
decreased from 25% to 7.9% from year 2002-2006
Fig. 3. Scheme and cone beam computed tomography scans
in their research analyzed practitioners’ inserted
image of the line between the root surface and the miniMI groups (Table 3). On the basis of these two
implant (Watanabe (34))
researches’ results, it can be concluded that one of
the surgery related factors affecting MI stability is
Motoyoshi et al. (35) researched the influence
practitioner’s experience.
of MI insertion torque on MI primary and secondThe influence of oral mucosa type on MI sucary stability. On the authors’ recommendations, 4cess rate was analyzed in five researches (7-11). In
N torque is sufficient for machine MI insertion. The
three articles (7-9) there was a statistically signifiMI insertion torque for older patients with thinnercant association between the mucosa type and MI
cortical bone in maxilla should be lower than insuccess rate determined: MI inserted in keratinizedmandible and younger patients (Table 3).
gingiva had higher success rates than MI inserted
in non-keratinized mucosa. However, in two articles
CONCLUSIONS
there was no statistically significant association
between the type of oral mucosa and MI success1. This systematic literature review’s results
rate determined (10, 11) (Table 3).
confi rm the sufficient success rate (87.7-

16

Stomatologija, Baltic Dental and Maxillofacial Journal, 2017, Vol. 19, No. 1

REVIEW

G. Gintautaitė1, A. Gaidytė

practitioners’ inserted
MI had 7.1-17.1% higher success rates).
3. Further controlled
clinical random samples researches withstrictly defined criteriafor MI characteristics,
insertion methods andABC
site, tracing, evaluaFig. 3. Root proximity categories used in Shigeeda’s (3) research: A – no contact between the mini- tion and performed by
implant and root, B – one point of contact between the root and apex or body of the mini-implant, experienced clinicians
C – two or more contacts between the root and mini-implant.
should be carried out.
4. Several definitions of MI “success”, “fail97%) of MI, inserted in buccal surface ofure”, “stability” exist in scientific literature.
jaw’s alveolar process between the fi rst
In our opinion, these definitions should be
molar and second premolar roots and allows
unified to achieve more homogeneity into assess MI as a reliable and beneficial
scientific researches. We suggest to call aanchorage device.
MI “successful”, which remains stable, func2. On the basis of analyzed researches’ results,
tions for all orthodontic treatment duration,
the MI stability affecting surgery relatedwith no surrounding soft tissue inflammation
factors are: the jaw (success rates in maxsigns or other undesirable consequences.
illa: 86.9-97.2%; in mandible: 70.69-93.7%),5.
Due to huge data heterogeneity, metaMI proximity to adjacent teeth roots (aanalyses instead of systematic literature
contact with root determined a 9.0-26.7%
reviews should be chosen to summarize thefailure rate), bone quality (the success rate
factors affecting MI stability.
of MI inserted in Q1-Q3 quality bone was
94.8-100%), oral mucosa type (MI success
STATEMENT OF CONFLICT OF INTEREST
rate in keratinized gingiva: 85.4-96.2%, in
non-keratinized gingiva: 62.5-75.2%) and
The authors state no conflict of interest.
practitioner’s experience (more experienced

REFERENCES
1. Schätzle M, Männchen R, Zwahlen M, Lang NP. Survival and failure rates or orthodontic temporary anchorage devices: a systematic review. Clin Oral Impl Res
2009;20:1351-9.
2. Rodriguez JC, Suarez F, Chan HL, Padial-Molina M,
Wang HL. Implants for orthodontic anchorage: successrates and reasons of failures. Implant Dent 2014;23:15561.
3. Shiggeda T. Root proximity and stability of orthodontic
anchor screws. J Oral Sci 2014;56:59-65.
4. Min KI, Kim SC, Kang KH, Cho JH, Lee EH, Chang
NY, et al. Root proximity and cortical bone thickness
effects on the success rate of orthodontic micro-implants
using cone beam computed tomography. Angle Orthod
2012;82:1014-21.
5. Jung YR, Kim SC, Kang KH, Cho JH, Lee EH, Chang
NY, et al. Placement angle effects on the success rate oforthodontic microimplants and other factors with conebeam computed tomography. Am J Orthod Dentofacial
Orthop 2013;143:173-81.
6. Shinohara A, Motoyoshi M, Uchida Y, Shimizu N. Rootproximity and inclination of orthodontic mini-implants
after placement: Cone-beam computed tomography evaluation. Am J Orthod Dentofacial Orthop 2013;144:50-6.
7. Manni A, Cozzani M, Tamborrino F, Rinaldis S, Minini

A. Factors influencing the stability of miniscrews. A
retrospective study on 300 miniscrews. Eur J Orthod
2011;33:388-95.
8. Lai TT, Chen MH. Factors affecting the clinical successof orthodontic anchorage: Experience with 266 temporaryanchorage devices. J Dent Sci 2014:9:49-55.
9. Sharma P, Valiathan A, Sivakumar A. Success rate of
microimplants in a university orthodontic clinic. ISRN
Surg 2011;2011:982671.
10. Lim HJ, Choi YJ, Evans CA, Hwang HS. Predictors of
initial stability of orthodontic miniscrew implants. Eur J
Orthod 2011;33:528-32.
11. Janson G, Gigliotti MO, Estelita S, Chiqueto K. Influenceof miniscrew dental root proximity on its degree of latestability. Int J Oral Maxillofac Surg 2013;42:527-34.
12. Wu TY, Kuang SH, Wu CH. Factors associated with thestability of mini-implants for orthodontic anchorage: astudy of 414 samples in Taiwan. J Oral Maxillofac Surg
2009;67:1595-9.
13. Spyridon N. Papageorgiou, Ioannis P. Zogakis, Moschos
A. Papadopoulos. Failure rates and associated risk factorsof orthodontic miniscrew implants: A meta-analysis. Am
J Orthod Dentofacial Orthop 2012;142:577-95.
14. Cheng SJ, Tseng IY, Lee JJ, Kok SH. A prospective
study of the risk factors associated with the failure of

Stomatologija, Baltic Dental and Maxillofacial Journal, 2017, Vol. 19, No. 1

17

G. Gintautaitė1, A. Gaidytė
mini-implants used for orthodontic anchorage. Int J Oral
Maxillofac Implants 2004;19:100-6.
15. Schneider G, Simmons K, Nason R, Felton D. Occlusal
rehabilitation using implants for orthodontic anchorage.
J Prosthodont 1998:7:232-6.
16. Upadhyay M, Yadav S, Nagaraj K, Patil S. Treatment
effects of mini-implants for en-masse retraction of anterior teeth in bialveolar dental protrusion patients: arandomized controlled trial. Am J Orthod Dentofacial
Orthop 2008;134:18-29.
17. Papadopoulos MA, Papageorgiou SN, Zogakis IP. Clinicaleffectiveness of orthodontic miniscrew implants. J Dent
Res 2011;90:969-76.
18. Kanomi R. Mini-implant for orthodontic anchorage. J
Clin Orthod 1997;31:763-7.
19. Poggio PM, Incorvati C, Velo S, Carano A. “Safe zones”:
a guide for miniscrew positioning in the maxillary andmandibular arch. Angle Orthod 2006;76:191-7.
20. Park HS. An anatomical study using CT image forthe implantation of micro-implants. Korea J Orthod
2002;32:435-41.
21. Moon CH, Lee DG, Lee HS, Im JS, Baek SH. Factors associated with the success rate of orthodontic miniscrews
placed in the upper and lower posterior buccal region.
Angle Orthod 2008;78:101-6.
22. Deguchi T, Nasu M, Murakami K, Yabuuchi T, Kamioka
H, Takano-Yamamoto T. Quantitative evaluation of cortical bone thickness with computed tomographic scanningfor orthodontic implants. Am J Orthod Dentofacial Orthop
2006;129:721.e7-12.
23. Kim SH, Yoon HG, Choi YS, Hwang EH, Kook YA, Nelson G. Evaluation of interdental space of the maxillaryposterior area for orthodontic mini-implants with conebeam computed tomography. Am J Orthod Dentofacial
Orthop 2009;135:635-41.
24. Joo E. Radiographic evaluation of interdental distance fororthodontic miniscrew application [thesis]. Seoul: Korea
Yonsei University; 2004.
25. Park HS. Clinical study on success rate on microscrew
implants for orthodontic anchorage. Korea J Orthod
2003;33:151-6.
26. Park HS, Jeong SH, Kwon OW. Factors affecting the clinical success of screw implants used as orthodontic anchorage. Am J Orthod Dentofacial Orthop 2006;130:18-24.

REVIEW
27. Miyawaki S, Koyama I, Inoue M, Mishima K, Sugahara
T, Takano-Yamamoto T. Factors associated with the stability of titanium screws placed in the posterior region fororthodontic anchorage. Am J Orthod Dentofacial Orthop
2003;124:373-8.
28. Kuroda S, Yamada K, Deguchi T, Hashimoto T, Kyung
HM, Takano-Yamamoto T. Root proximity is a major
factor for screw failure in orthodontic anchorage. Am J
Orthod Dentofacial Orthop 2007;131(Suppl):S68-73.
29. Chaddad K, Ferreira AFH, Geurs N, Reddy MS. Influence of surface characteristics on survival rates of miniimplants. Angle Orthod 2008;78:107-13.
30. Kuroda S, Sugawara Y, Deguchi T, Kyung HM, TakanoYamamoto T. Clinical use of miniscrew implants as orthodontic anchorage: success rates and postoperative discomfort. Am J Orthod Dentofacial Orthop 2007;131:9-15.
31. Reynders R, Ronchi L, Bipat S. Mini-implants in orthodontics: A systematic review of the literature. Am J Orthod
Dentofacial Orthop 2009;135:564.e1-564.e19.
32. Papageorgiou SN, Zogakis IP, Papadopoulos MA. Failure
rates and associated risk factors of orthodontic miniscrew
implants: A meta-analysis. Am J Orthod Dentofacial Orthop 2012;142:577-95.
33. Feldmann I, Bondemark L. Orthodontic anchorage: asystematic review. Angle Orthod 2006;76: 493-501.
34. Watanabe H, Deguchi T, Hasegawa M, Ito M, Kim S,
Takano-Yamamoto T. Orthodontic miniscrew failure rate
and root proximity, insertion angle, bone contact length,and bone density. Orthod Craniofac Res 2013;16:45-55.
35. Motoyoshi M, Uemura M, Ono A, Okazaki K, Shigeeda
T, Shimizu N. Factors affecting the long-term stabilityof orthodontic mini-implants. Am J Orthod Dentofacial
Orthop 2010;137:588.e1-588.e5.
36. Kim SH, Kang SM, Choi YS, Kook YA, Chung KR, Huang
JC. Cone-beam computed tomography evaluation ofmini-implants after placement: Is root proximity a majorrisk factor for failure? Am J Orthod Dentofacial Orthop
2010;138:264-76.
37. Lekholm U, Zarb GA. Patient selection and preparation.
In: Tissue integrated prostheses: osseointegration inclinical dentistry. Branemark PI, Zarb GA, Albrektsson T,
editor. Chicago: Quintessence Publ Co; 1985. P. 199-209.

Received: 19 03 2015
Accepted for publishing: 27 03 201718

Stomatologija, Baltic Dental and Maxillofacial Journal, 2017, Vol. 19, No. 1