1
Chen Lugaccy-Waismann
5th Course, group 13INTRUSION OF MAXILLARY INCISORS BY
MINI-IMPLANTS
A systematic review
Supervisor
PhD, Arūnas Vasiliauskas
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LITHUANIAN UNIVERSITY OF HEALTH SCIENCES MEDICAL ACADEMY
FACULTYOFODONTOLOGY
THECLINICOFORTHODONTICS
INTRUSION OF MAXILLARY INCISORS BY MINI-IMPLANTS
A systematic review
The thesis was done
by student ………... supervisor ………...
(name surname, year, group) (degree, name surname)
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(signature) (signature)
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EVALUATION TABLE OF THE MASTER’S THESIS OF THE TYPE
OF SYSTEMIC REVIEW OF SCIENTIFIC LITERATURE
Evaluation:
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Reviewer:
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(scientific degree. name and surname)
Reviewing date: ...
No. MT parts MT evaluation aspects
Compliance with MT requirements and evaluation Yes Partially No 1 Summary (0.5 point)
Is summary informative and in compliance with the
thesis content and requirements? 0.3 0.1 0
2 Are keywords in compliance with the thesis
essence? 0.2 0.1 0
3 Introduction, aim and tasks (1 point)
Are the novelty, relevance and significance of the
work justified in the introduction of the thesis? 0.4 0.2 0
4 Are the problem, hypothesis, aim and tasks formed
clearly and properly? 0.4 0.2 0
5 Are the aim and tasks interrelated? 0.2 0.1 0
6 Selection criteria of the studies, search methods and strategy
(3.4 points)
Is the protocol of systemic review present? 0.6 0.3 0 7
Were the eligibility criteria of articles for the selected protocol determined (e.g., year, language, publication condition, etc.)
0.4 0.2 0
8
Are all the information sources (databases with dates of coverage, contact with study authors to identify additional studies) described and are the last search day indicated?
0.2 0.1 0
9
Is the electronic search strategy described in such a way that it could be repeated (year of search, the last search day; keywords and their combinations; number of found and selected articles according to the combinations of keywords)?
0.4 0.1 0
10
Is the selection process of studies (screening, eligibility, included in systemic review or, if applicable, included in the meta-analysis) described?
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Is the data extraction method from the articles (types of investigations, participants, interventions, analyzed factors, indexes) described?
0.4 0.2 0
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Are all the variables (for which data were sought and any assumptions and simplifications made) listed and defined?
0.4 0.2 0
13
Are the methods, which were used to evaluate the risk of bias of individual studies and how this information is to be used in data synthesis, described?
0.2 0.1 0
14 Were the principal summary measures (risk ratio,
difference in means) stated? 0.4 0.2 0
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Systemization and analysis of data
(2.2 points)
Is the number of studies screened: included upon assessment for eligibility and excluded upon giving the reasons in each stage of exclusion presented?
0.6 0.3 0
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Are the characteristics of studies presented in the included articles, according to which the data were extracted (e.g., study size, follow-up period, type of respondents) presented?
0.6 0.3 0
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Are the evaluations of beneficial or harmful outcomes for each study presented? (a) simple summary data for each intervention group; b) effect estimates and confidence intervals)
0.4 0.2 0
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Are the extracted and systemized data from studies presented in the tables according to individual tasks?
0.6 0.3 0
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Discussion (1.4 points)
Are the main findings summarized and is their
relevance indicated? 0.4 0.2 0
20 Are the limitations of the performed systemic
review discussed? 0.4 0.2 0
21 Does author
results?
present the interpretation of the
0.4 0.2 0
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Conclusions (0.5 points)
Do the conclusions reflect the topic, aim and tasks
of the Master’s thesis? 0.2 0.1 0
23 Are the conclusions based on the analysed material? 0.2 0.1 0
24 Are the conclusions clear and laconic? 0.1 0.1 0
25 Is the references list formed according to the
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References (1 point)
Are the links of the references to the text correct? Are the literature sources cited correctly and precisely?
0.2 0.1 0
27 Is the scientific level of references suitable for
Master’s thesis? 0.2 0.1 0
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Do the cited sources not older than 10 years old form at least 70% of sources, and the not older than 5 years – at least 40%?
0.2 0.1 0
Additional sections, which may increase the collected number of points
29 Annexes Do the presented annexes help to understand the
analysed topic? +0.2 +0.1 0
30
Practical recommend- dations
Are the practical recommendations suggested and
are they related to the received results? +0.4 +0.2 0
31
Were additional methods of data analysis and their results used and described (sensitivity analyses, meta-regression)?
+1 +0.5 0
32
Was meta-analysis applied? Are the selected statistical methods indicated? Are the results of each meta-analysis presented?
+2 +1 0
General requirements, non-compliance with which reduce the number of points
33
General requirements
Is the thesis volume sufficient (excluding annexes)?
15-20 pages (-2 points)
<15 pages (-5 points)
34 Is the thesis volume increased
artificially? -2 points -1 point
35 Does the thesis structure satisfy the
requirements of Master’s thesis? -1 point -2 points
36 Is the thesis written in correct
language, scientifically, logically and laconically?
-0.5 point -1 points
37 Are there any grammatical, style or
computer literacy-related mistakes? -2 points -1 points
38 Is text consistent, integral, and are the
volumes of its structural parts balanced?
-0.2 point -0.5 points
39 Amount of plagiarism in the thesis. >20%
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40
Is the content (names of sections and sub- sections and enumeration of pages) in compliance with the thesis structure and aims?
-0.2 point -0.5 points
41
Are the names of the thesis parts in compliance with the text? Are the titles of sections and sub-sections distinguished logically and correctly?
-0.2 point -0.5 points
42 Are there explanations of the key
terms and abbreviations (if needed)? -0.2 point -0.5 points
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Is the quality of the thesis typography (quality of printing, visual aids, binding) good?
-0.2 point -0.5 points
*In total (maximum 10 points):
*Remark: the amount of collected points may exceed 10 points.
Reviewer’s comments: ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ Reviewer’s name and surname Reviewer’s signature _________________________ ___________________
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TABLE OF CONTENTS
ABSTRACT………... page 1-2 INTRODUCTION……….…. page 3-5 SELECTION CRITERIA OF THE STUDIES. SEARCH METHODS AND STRATEGY ……….…….. Page 6-8 SYSTEMIZATION AND ANALYSIS OF DATA…………..………..…. page 9-11 RESULTS………... page 12-19 DISCUSSION………. page 20-24 CONCLUSION……….…... page 25 PRACTICAL RECOMMENDATIONS………..……… page 26 REFERENCES………... page 27-29 ANNEXES………..page 30
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ABSTRACT
Objectives:
The purpose of this systematic literature review is to evaluate the effects ofdifferent insertion sites of mini-implants / TAD’s (temporary anchorage device) on the treatment of deep overbite and/or gummy smile with maxillary incisors intrusion.
Material and methods:
In this systematic review search performed of the published data in several electronic databases included PubMed, Science Direct, Cochrane and other sources as AJO-DO and European journal of orthodontics up to January 2017.Inclusion criteria were: English language, only humans, articles published from January 1st, 2008 till 5th ofJanuary 2018, patients with deep overbite and/or gummy smile treated with maxillary incisors intrusion by using temporary anchorage device and studies that present records of pretreatment and posttreatment. Study selection, risk of bias assessment, and data-extraction were performed.
Results:
In total 297 scientific publications, articles, clinical trials reviews were identified and were related to keywords used during the search. Out of the 34 articles that met the initial eligibility criteria, 8 studies were finally selected. Low to moderate level of scientific evidence was identified after risk of bias assessment on the included studies with no relevant randomized controlled trial performed. In the final included studies, five mini implants insertion sites possibilities used for maxillary incisors intrusion were presented and a comparison between them was made. There were differences in the outcomes and results. Treatment duration vary from four months to more than a year. Minimum force applied on each mini implant was 40g while maximum force applied was 90g.The highest result of total intrusion was 5.62mm, which was achieved by one mini implant located 4mm superior to the free gingival margin between the central incisors, and the lowest result of total intrusion was 1.56mm seen in the use of 2 mini implants inserted between the second premolar and first molar. Some studies reported on no failure while others reported on 6.25% to 14.3% of mini implants lost.
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important role when intrusion of 4 maxillary incisors are considered, it substantially affects the mean of total intrusion, the treatment duration need, and the force required to apply on each mini-implants.
In addition, by this systematic review we can conclude that the best results and outcomes achieved when one mini-implant was inserted between the maxillary central incisors
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INTRODUCTION
Marcotte explained intrusion as an apical movement of the tooth which at infinity lies its center of rotation. It is an axial type of translation [1]. Burstone roughly explained intrusion as a movement based on the long axis of the apical tooth, or a geometric one with respect to the occlusal plane [2].
Nikolai’s description for intrusion was that it is an apical movement paralleled to the long axis of the tooth which is the tooth’s transitional form of movement [3].
An intrusion may be relative or true, and a tooth’s movement apically, along its long axis is a true one. An intrusion that has the incisors remain on their place while there is a growth of mandible and an eruption of the posterior teeth- is relative intrusion [4].
This systematic review will focus on true intrusion only. Intrusion is a common treatment used in orthodontic management of Esthetic and functional problems, inclusive deep overbite and gummy smile [5]. Deep overbite phenomenon can be described as a substantial overlap by the incisors of the maxilla over the incisors of the mandible when the mandible is at central occlusion or at habitual occlusion. [6]
The main reason to treat deep bite and/or gummy smile conditions by intrusion of maxillary incisors is esthetic improvement, but there are some harmful effects such as: incisor wear, palatal impingement, gingival recession [6], that can heal efficiently by treating the beforementioned conditions with true intrusion of maxillary incisors.
In the past, dental intrusion was considered problematic or impossible and was associated with side effects affecting the cementum and the periodontium, such as root resorption. However, at present time, orthodontic intrusion is clinically documented as successful and regarded to as safe [5] .
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Before mini-implants (MI) or temporary anchorage device (TAD’s) were invented, orthodontics primarily used other techniques for maxillary incisors intrusion, such as: Rickett’s utility arch, Kalra's Simultaneous Intrusion & Retraction arch, Arch with Reverse Curve of Spee and Cervical headgear and lever arches. [6-7]. A research that investigated the differences between the intrusive effects of mini-implants to utility arches technique established that: “mini-implant in contrast to others, produce true intrusion without any other side effects” [8]. Another research showed that the amount of intrusion is significantly higher in the group which was treated by mini-implant, had overall better results and was easier in handling during intrusion. [9]
Thus, the treatment for gummy smile or anterior deep overbite by mini-implants in the maxillary anterior region is crucial. [10]
The first MI of 1.2 mm diameter and 6 mm length were introduced in 1997. [11]
It was proved that mini-implants insertion is a versatile surgery which is minimally invasive without any assault towards the dental roots, it has easy insertion and removal, readily loaded after initial wound healing, and has a low cost. [12,13,14]. Contrarily, the effects of mini-implants and their retention depend on many factors such as: location of insertion, bone quality, force applied, treatment duration, mini-implant length and diameter, angle of insertion, etc.
The goal of the current report is to systematically review the effects of different mini-implant insertion sites on maxillary incisors intrusion.
Intrusion of maxillary incisors by mini-implants can be done by various techniques, different types of implant which vary in properties, and can differ in quantity of mini-implants used and magnitude of force applied. In the following review a comparison will be performed between the various insertion sites and which effect each to of the sites has on the results. The insertion sites that will be compared and discussed are the following: - 1) one mini-implant between maxillary central incisors.
- 2) two symmetrical mini-implants between 2nd premolar and 1st molar (U5-U6) - 3) two symmetrical mini-implants between lateral incisor and canine (U2-U3) - 4) two symmetrical mini-implants between central and lateral incisors (U1-U2)
- 5) four symmetrical mini-implants anteriorly between lateral incisor and canine (U2-U3), posteriorly between 2nd premolar and 1st molar (U5-U6).
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The hypothesis of this systematic review was that the insertion site of the mini-implant has an important role when intrusion of 4 maxillary incisors is considered. (it can gradually affect the results and outcomes of the treatment.)
Therefore, the main aim of this systematic review was to evaluate and compare the effects of different insertion sites of mini-implant on the maxillary incisors intrusion results. Our tasks were:
1) To evaluate the effect of different mini-implant insertion sites on the total maxillary incisors intrusion amount.
2) To evaluate the effect of different mini-implant insertion sites on the time needed for maxillary incisors intrusion.
3) To evaluate the effect of different mini-implant insertion sites on the force needed to apply for maxillary incisors intrusion.
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SELECTION CRITERIA OF THE STUDIES.
SEARCH METHODS AND STRATEGY
This systematic review was performed according to the protocol of PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) statement for reporting systematic reviews of the health sciences. [15]
Search strategy:
The systematic literature review was based on a selection from a main information source. The main information source was literature studies from electronic databases that were found during a search in Google web browser.
The keywords that were used in thesearch were: maxillary incisors intrusion, mini implant, mini screw, TAD, SAD. (TAD: temporary anchorage device, SAD: skeletal anchorage device).
Comprehensive electronic searches up to January 5th, 2018 were conducted in the following databases: PubMed, Cochrane, Scopus, Science direct, Journal seek and MedlinePlus.
In addition, the following journals were searched individually to find out any missing articles: American Journal of Orthodontics and Dentofacial Orthopedics (AJO-DO) and European Journal of Orthodontics-OXFORD Journals. Moreover, references in found articles that led to additional relevant articles.
The literature search included assessment of articles from dental journals that were in the English language,studies that were performed on humans only and published in the years from January 1st 2008 till 5th ofJanuary 2018 and included the selected keywords. In PubMed database and other databases with the same method of Advanced search, search strategy performed as:( “mini implant” OR “mini screw” OR “TAD” OR “SAD”) AND “maxillary incisors intrusion”.
In ScienceDirect the method of Advanced search act differently, therefore the search strategy in this case was: “maxillary incisor intrusion” in the main search, and in advanced category of: “With words in title, abstract or keywords” we added: “mini implant OR mini screw OR TAD OR SAD” .
Search strategy in American Journal of Orthodontics was the same as performed in PubMed.
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However, in European Journal of Orthodontic- OXFORD Academy, we could not perform advanced search with combination of: AND and OR, therefore in this case, search keyword was only:” maxillary incisor intrusion”.
In total after duplicates removed 297 scientific publications, articles and clinical trials reviews were identified and were related to keywords used during the search.
Titles and abstracts derived from this broad search were independently screened to eliminate irrelevant publications and individual case reports.
The final stage of screening involved reading the full texts to confirm the eligibility of each study, based on inclusion and exclusion criteria. The focused aim was: To evaluate the effect of different MI insertion sites on maxillary incisors intrusion results.
Selection criteria: (PICOS question: population, intervention, comparison, outcome, study designs).
The following eligibility criteria were used to determine eligible reports for this systematic review:
Population: Adolescent and adult patients with deep overbite malocclusion and/or gummy smile. Only human studies were included without consideration of gender.
Intervention: Patients undergoing orthodontic treatment for deep overbite and/or gummy smile correction by maxillary incisors intrusion using temporary anchorage devices. Comparison: between temporary anchorage devices techniques and different insertions sites for maxillary incisors intrusion.
Outcomes: there are different effects on total maxillary incisors intrusion, duration of treatment and applied force on MI insertion in the different sites.
Study design: Randomized and non-randomized controlled trials, clinical trials (prospective and retrospective), and case series studies. Excluded articles included case reports with ≤ 5 subjects, animal studies, review articles, abstracts, and discussions.
The inclusion criteria for this systematic review are: 1. All the study subjects are humans.
2. Years of articles publication were chosen from January 1st 2008 till the 5th ofJanuary 2018.
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by using temporary anchorage device.
4. studies that present records of pretreatment and posttreatment. 5. English language.
The exclusion criteria are: 1. Non- human studies. 2. In vitro studies.
3. literature reviews, abstracts, single case reports, editorials, commentaries. 4. articles included case reports with ≤ 5 subjects.
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SYSTEMIZATION AND ANALYSIS OF DATA
The articles review, and data extraction were performed according to PRISMA flow diagram (Figure 1) [15]. The initial database search displayed 310 results. The preliminary exclusion was done by relevancy; 13 duplicated titles and abstracts were excluded. After records screened of the remaining 297 articles result, 263 were excluded due to not enough information, article with no access, not full text of articles, due to language (not in English), single case reports, literature reviews and discussions articles. 34 full-text articles assessed for eligibility.
Finally, 8 articles were included in the review. A flow chart of the selection process is presented in Figure 1.
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Assessment of methodological quality
The quality of all included studies were assessed during the data extraction process and involved evaluating the methodological elements that might influence the outcome of each study (Table 1).
Table 1: Cochrane Risk of bias summary
Chandrase kharan D. et al. 2010 Sachin P. et al. 2014 Polat-Ozsoy O. et al. 2009 Sensk N. et al. 2012 Ravindra-Kumar J. et al. 2014 Prasanna K. et al. 2017 Alaty M. 2015 Aras I. et al. 2016 random sequence generation ? ? ? ? ? ? ? ? allocation concealment ? ? ? ? ? ? ? ? blinding of participants and personnel ? ? ? ? ? ? ? ? blinding of outcome assessment ? ? ? ? ? ? ? ? incomplete outcome data + - + + - + - + selective reporting + - + + + + - + other bias + + + + + + - +
Categories as follows: low risk of bias (+), unclear risk of bias (?), or high risk of bias (-)
The Cochrane handbook for assessing risk of bias [16] was used to assess bias across the studies and to identify papers with intrinsic methodological and design flaws. Based on the information given in each study the potential risk of bias was categorized into: low risk of bias (+), unclear risk of bias (?), or high risk of bias (-). According to Cochrane evaluation the included researches have unknown risk of bias. However, Cochrane evaluation for risk of bias is more suitable for Randomized studies, but all our included articles are Non-Randomized (prospective or retrospective researches), therefore most of our results were “unclear” and to better evaluate the risk of bias, additional evaluation is needed.
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Additional assessment was done by using the methodological index for non-randomized trials (MINORS) tool with a minor modification (Annex 1) [17].
Quality assessment
All studies included in our methodological scoring process have moderate quality as presented in Annex 1. Randomization and blinding were not mentioned in any studies. Follow up and evaluation after the end of treatment period was not done in any of the 8 included studies, although a long-term follow-up of these cases is needed to study the possibility of a relapse. After a correction of deep overbite, as in all orthodontics treatment, a relapse can occur and therefore an overcorrection should be taken into consideration.
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RESULTS
Detailed report of outcome measurements and characteristics for each study are presented in Tables 2,3 and 4.
Table 2: Characteristics of studies included in systematic review.
Author and year of publication
Study design Sample of subjects
Age (years)
Material used Method of measurement Chandrasekh aran D. et al 2010 prospective study 21 (9 boys, 12 girls) 12- 18 Titanium mini implant,1.5 mm diameter, 6mm length, low profile heads
Pretreatment and posttreatment study casts Sachin P. et al. 2014 observational study
10 - bracket head mini
implants pretreatment and posttreatment lateral cephalograms Polat-Ozsoy O. et al. 2009 prospective study 11 ( 3 male,8 female) mean of 19.79 ± 4.79 Mini implant 1.2mm in diameter, 6 mm length (Absoanchor,Dentos,T aegu, Korea) pretreatment and posttreatment lateral cephalograms Ebru Sensk N. et al. 2012 prospective study 15 ( 6 men, 9 women) mean age 20.13 +- 2.48 (min 16.9 max 24.3) self-drilling mini-implants diameter 1.3 mm; length 5mm (Absoanchor; Dentos,Daegu, South Korea) pretreatment and posttreatment cephalograms
13 Ravindra-Kumar J. et al. 2014 prospective study 10 16-22 Mini implant of 6 mm length, 1.4 mm diameter (Absoanchor by Dentos, Daegu Korea) pretreatment and posttreatment cephalograms Prasanna K. et al. 2017 prospective study 15 15-20 Self-drilling micro-implants of diameter 1.3mm and length 7 mm (AbsoAnchor®, Dentos, Daegu, Korea) pretreatment and posttreatment lateral cephalograms Alaty M. 2015 prospective study 15 (2 males, 13 females) mean age 22.5+- 2.5
-Two anterior mini screws, 6mm length 1.2mm diameter (AbsoAnchor®) -Two Posterior mini-screws, 8mm length 1.4mm diameter (AbsoAnchor®) Pretreatment and posttreatment GSL*, measured in millimetres using a digital caliper. Aras I. et al. 2016 prospective study 16 (10 females, 6 males) mean age 19.31+- 3.84 self-drilling mini-implants, 1.4 mm diameter and length of 6 mm
(NeoAnchor Plus, Los Angeles, Calif) Pretreatment and posttreatment CBCT** measurements Aras I. et al. 2016 prospective study 16 (10 females, 6 males) 19 +- 3.48 self-drilling mini-implants, 1.6 mm diameter and 7 mm length (NeoAnchor Plus, Los Angeles, Calif) Pretreatment and posttreatment CBCT measurements
* GSL= gingival smile line, which is the distance between cervical gingival margins of maxillary central incisors and the lower border of the upper lip during smiling.
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Out of the 8 selected studies one was designed as observational study, the rest as prospective studies [8-9, 18-23].
In the last included article (Aras I. et al. 2016) [23] a comparison was made between two groups of patients, with two different insertion sites of mini-implants, one group treated with mini implants located between lateral incisor and the canine, while the second group was treated with mini-implants located between the second premolar and the first molar. Thus, in all the characteristics and outcome measurements tables, the study was mentioned twice while assigned each group separately.
The average sample of subjects of all the included studies is 14.33, with the lowest sample of 10 [19] and highest sample of 21 [18] with female predominance. The range of age is varied from 12 to 25 years old. However, one study did not mention the age of the sampled subjects (Sachin P. et al. 2014) [19].
Five out of the eight included studies chose TAD length of 6mm, one used 5mm [21] and final two studies used TAD with more than 6mm in length (7mm and 8mm) [9,22-23]. The range of TAD’s diameter varied from 1.2 to 1.6 mm.
Most of the studies measured pretreatment and posttreatment parameters using lateral cephalometric radiograph, two used cone beam computed tomography (CBCT) [23], one study measured pretreatment and posttreatment study casts [18], and in the study of Alaty M. 2015, the method of measurement was before and after intrusion GSL- gingival smile line which is the distance between cervical gingival margins of maxillary central incisors and lower border of the upper lip during smiling (measured by digital caliper in millimeters) [22]
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Table 3: Summary of outcomes of selected studies
Author and Year of publication Number of mini implants Location of mini implant Treatment time (months) Force applied (grams) Mean of intrusion per month (mm/months) Mean of total intrusion (mm) Chandrasekhar an D. et al. 2010 1 4mm superior to the free gingival margin between the central incisors. 4 50-60 1.4 5.62 Sachin P. et al 2014 2 between the root of the 2nd premolar and the mesial root of the 1st molar 5 60 0.49 2.45 Polat-Ozsoy O. et al. 2009 2 distally to the maxillary lateral incisors, at the mucogingival junction 4.55 ± 2.64 80 0.42 1.9+-1.1 Sensk N. et al. 2012 2 between the roots of the lateral incisors and canines at the mucogingival junction. 7 90 0.34 2.47 Ravindra-Kumar J. et al. 2014 2 between the maxillary central and lateral incisors 4 42.5 0.53 2.1 Prasanna K. et al. 2017 2 between maxillary lateral incisors and central incisors 6 60 0.51 3.10 (SD 0.67)
16 Alaty M. 2015 4 two anterior TADs between the roots of lateral incisors and canines; two posterior TADs between the roots of 2nd premolars and 1st molars. 13.133 - 0.34 4.4 Aras I. et al. 2016 2 between lateral incisor and canine 4 40 0.62 2.48 Aras I. et al. 2016 2 between the second premolar and first molar 4 40 0.39 1.56
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Table 3 shows the effect of different insertion sites of mini-implants on: the number of mini-implants needed, treatment duration, force applied on each mini-implant, mean of intrusion per month (mm) and mean of total intrusion at the end of treatment (mm). One study performed maxillary incisors intrusion by using only one mini-implant located 4mm superior to the free gingival margin between the central incisors (Chandrasekharan D. et al. 2010) [18]. Out of nine groups of study, seven used two mini-implants, out of those: two studies inserted site was between the maxillary central and lateral incisors, three studies inserted the mini-implants between lateral incisors and canines, and additional two studies chose to insert the mini-implants between 2nd premolar to 1st molar roots. In differ to the previous mentioned studies, one study (Alaty M. 2015) [22] used a bigger amount of mini-implants- 4 in total, 2 inserted in anterior region and 2 in posterior region. The anterior mini-implants inserted between the roots of lateral incisors and canines and the posterior mini-implant inserted between the roots of 2nd premolars and 1st molars.
Treatment duration vary from four months to more than a year. Minimum force applied on each mini-implant was 40g [23] while maximum force applied was 90g [21].
The highest result of total intrusion was 5.62 mm, which achieved by one mini-implant between the central incisors (Chandrasekharan D. et al. 2010) [18]. The lowest result of total intrusion was 1.56 mm seen when two mini-implants were inserted between the 2nd premolar and 1st molar (Aras I. et al. 2016) [23].
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Table 4: Summary of failures and side effects of selected studies Author and Year of
publication
Failure Side effects Chandrasekharan D.
et al. 2010
Three patients had loosening of the micro-implants, which were later replaced.
proclination of maxillary incisors
Sachin P. et al. 2014
- Incisors protruded with respect to NA
line by 0.5mm.
Incisors proclined with respect to the palatal plane, SN and NA line by 2.6º (p=0.028), 3.3º (p=0.027) and 2.9º (p=0.032)
Polat-Ozsoy O.et al. 2009
One screw was replaced due to close proximity to one of the lateral roots, and two due to postoperative infection and mobility.
Incisors were protruded 0.79+-1.4 mm (p> 0.05) relative to pterygoid vertical and 3.85º+-2.4º (p>0.05) related to palatal plane
Sensk N. et al. 2012
3 mini-implants loosened in the first month of orthodontic force loading; these were replaced immediately. The new insertion place of the mini-implants was 1mm above the first insertion place.
Protrusion of maxillary incisors (p<0.05), protrusion and extrusion of the mandibular incisors (p<0.05)
Ravindra-Kumar J. et al. 2014
- No side effects
Prasanna K. et al. 2017
no failure Vertical molar positional change and
incisors inclination in mean of 0.93 degree (SD+- 1.27) Alaty M. 2015 - - Aras I. et al. 2016
One patient was excluded due to mini-implant loosening
Distal movement of incisors with labial tipping. Volumetric root resorption
Aras I. et al. 2016
no failure Distal movement of incisors with
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Table 4 presents a summary of failures and side effects of selected studies.
The meaning of failure in this systematic review (and as mentioned in the included studies) was: loosening of mini-implant during the treatment period.
Two studies declared: “No failure”.
In the study of Chandrasekharan D. et al. 2010 [18] with strategy method of one mini-implant between central incisors, three patients had loosening of the mini-mini-implants. Failure of 3 inserted mini-implant has been seen in the study of Polat-Ozsoy O.et al. 2009, [20] when using two mini implants inserted between the lateral incisor and the canine. The same number of mini-implants loosening (three) were observed in the study of Sensk N. et al. 2012 [21] while using the same insertion site of mini-implants (between lateral incisor and canine).
All the cases of failure that were mentioned above, in all the three studies, were fixed with replacing the mini implants. In contrast, in the study of Aras I. et al.2016, [23] one case observed with loosening of implant and it was not fixed by replacing the mini-implants, but this patient excluded from the study.
The reasons for the loosening of mini-implants were: 1) Postoperative infection.
2) Postoperative mobility of mini-implant 3) Close proximity to one of the roots.
The rest of the studies not mentioned about failure or loosening of mini implants. [8,19,22]. The main side effect was protrusion of maxillary incisors, other side effects were: root resorption, inclination of maxillary incisors, distal movement of incisors with labial tipping, proclination of maxillary incisors, protrusion and extrusion of the mandibular incisors and vertical molar positional changes.
Only one of all included studies (Ravindra-Kumar J. et al. 2014) [8] declared: No side effects.
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DISCUSSION
During our assessment and evaluation of the data in the including studies and while working on this systematic review, we found an interesting fact: there were more female participants in the researches samples.
Our assumption is that this fact stems from the innate nature of women towards esthetics and not because women tend to suffer more from deep overbite and/or gummy smile condition than men.
In addition, with the data we gathered, out of all TAD’s available at present time, we found that the TAD which was used the most for maxillary incisors intrusion was mini implant with characteristics of 6mm length and 1.2-1.4 mm of diameter.
Furthermore, we found that the different insertion sites of MI indeed influenced the results and the outcomes of the intrusion treatment and those are explained separately in detail at the following paragraphs.
The first insertion site that we evaluated, in the study of Chandrasekharan D. et al. [18] was one mini implant between maxillary central incisors (U1-U1).
Among 21 patients, the mean of total intrusion was 5.62mm which is the highest result of all the other data we have gathered and by a large margin, and under only four months of treatment. In this method of treatment, the mini implant endured 50-60 grams of force which is approximately the average amount of force applied in all the included studies. (average is 58.4g). Chandrasekharan D. et al reported-on failure of 3 out of 21 patients (~14.3%), and proclination of maxillary incisors as side effect.
Although the results of MI insertion in U1-U1 region were very stratified, the percentages of failure were the highest and insertion at this site is not esthetically pleasing. However, this method was found to be more conservative than others due to the fact that only one MI insertion was needed.
The second insertion site that we evaluated was between the central and the lateral incisors (U1-U2), in this technique two mini implants were used. The data presented in two of our included studies: Ravinda-Kumar J. et al. and Prasanna K. et al. [8, 9]. The mean of total intrusion achieved respectively was 2.1mm and 3.1mm and these results were found to be satisfying.
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Answering to question why a vastly different results (1 mm of difference) were achieved when the same insertion site was used, we assume that the different results stem from the differences in the duration of treatment and we could conclude this by observing the results of the mean of intrusion per month values that were almost the same: 0.51mm and 0.53mm. While in the study of Ravinda-Kumar J. et al. [8] the total duration of treatment was 4 months with 42.5g of force applied on each mini implant, in the study of Prasanna K. et al. [9] the duration of treatment was 6 months, with 60g of force applied on each mini implant. From that, we can conclude that to perform an intrusion of maxillary incisors by using 2 mini implants located between the central and the lateral incisors, there is no need to use force above 42.5g because it makes no difference at all when 60g are used. In addition, if we want to increase the total amount of intrusion it is better to prolong the duration of treatment by few more months.
In contrast to the other studies, Ravinda-Kumar J. et al. [8] was the only study that reported on no side effects at all and the study of Prasanna K. et al. [9] was one of two studies, out of 9, that had reported on no failure.
The third insertion site evaluated in this systematic review was 2 mini implants between the lateral incisors and the canines (U2-U3). There were three involved studies: Polat-Ozsoy O. et al, Sensk N. et al and Aras I. et al. [20, 21, 23]
The mean of total intrusion was respectively: 1.9mm, 2.47mm and 2.48mm.
Although the same insertion site was used, the treatment method used in the studies differed by the force applied on each mini implant (80g, 90g and 40g), the duration of treatment (4.55months, 7months and 4months) and the mean of intrusion per month (0.42mm/month, 0.34mm/month and 0.62mm/month).
From the summary of all the results and outcomes, we can deduce that: the bigger the force and the longer the duration of treatment were, a smaller mean of intrusion per month was observed.
In addition, the prospective studies of Polat-Ozsoy O. et al. and Sensk N. et al. [20, 21] reported on a failure of 3 mini-implants.
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In order to calculate the percentage of failure, a ratio between the number of loosen MI and the total screwed MI must be done, doing this led to us the following results: 9.1% and 10% of failure respectively, while the prospective study of Aras I. et al. [23] showed only 6.25% failure. Moreover, according to the data we collected, the three studies that used U2-U3 as MI insertion site reported on several side effects, including: protrusion of maxillary incisors, protrusion and extrusion of mandibular incisors and root resorption. The forth insertion site that we evaluated was: U5-U6, two mini implants were inserted in between 2nd premolar and 1st molar.
This insertion site has the benefit of being more esthetically pleasing, due to the fact that the mini implants are inserted in posterior region, hidden from sight during smiling, laughing and speaking.
Two studies from our systematic review used this insertion site: Sachin P. et al. and Aras I. et al. [19, 23]. The first study by Sachin P. et al. [19] resulted in 2.45mm mean of total intrusion while applied 60g of force on each mini-implant and the treatment lasted for five months. The second study by Aras I. et al. [23] resulted in only 1.56mm mean of total intrusion while applied 40g of force in duration of four months. Out of nine studies, this study earned the lowest amount of intrusion and therefore the least advisable to follow but, on the other hand no failures were reported in contrast to the other studies.
A newly published systematic review done by: Gintautaitė G. and Gaidytė A. (2017) found out that the success rate of mini-implant inserted in the maxilla between 2nd premolar and 1st molar is 86.9-97.2%, which is satisfying. [24]
In conclusion, in order to preform intrusion of maxillary incisors by insertion of mini-implants in the posterior region, a bigger force is needed, and a longer duration of treatment is required.
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One study by Alaty M. [22] performed another method of treatment, using four mini-implants: two located anteriorly: between the lateral incisors and the canines and two located posteriorly between the 2nd premolars and the 1st molars. The fact that this study had incomplete outcomes and data (missing: force applied in grams, failures and side effects), makes the comparison difficult. Nonetheless, the achievement of 4.4mm mean total intrusion is outstanding, but the duration of treatment was doubled and even tripled compared to other techniques.
At the beginning of this study it was cited that one of the major advantage of mini-implants over other orthodontic methods dealing with intrusion of maxillary incisors is the fact that it holds no side effects. And while examining the studies used in this systematic review, we surprisingly found several side effects that can be due to mini-implants use as a treatment for deep bite and/or gummy smile. However, compared to other techniques the side effects of mini-implants usage were reduced substantially.
While analyzing all the discussed data, its apparent that there are differences on the achieved results if several insertion sites of mini-implants are compared.
Unfortunately, we cannot put our finger on the exact reason of why that is. It might be influenced not only by the force applied and/or the treatment duration but also by the difference in the age of the patients, materials used, changes in the proximity of the mini-implant to the teeth’s roots and the density of the bone itself. All those and more should be further investigated in future clinical researches.
Limitations:
There is no doubt that the number of studies available in our days are not enough to reliably answer all the questions. There are no randomized clinical trials performed focused on the deep bite and/or gummy smile treatment using temporary anchorage devices. Presence of randomization is an important issue to consider when determining the best treatment modality for maxillary incisors intrusion.
It is clinically important to investigate the amount of maxillary incisors protrusion, inclination and bone resorption during deep overbite and/or gummy smile treatment while using TAD’s in comparison between the different options of insertion sites,
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as well as evaluation of the long-term stability of maxillary incisors intrusion by different techniques. The drawbacks in most of the articles such as absence of untreated control groups, absence of follow-up period, small sample size, and presence of confounding factors should be avoided in future studies so as to reach a more accurate conclusion concerning deep overbite and some of the gummy smile treatment.
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CONCLUSIONS
Our hypothesis that the decision regarding the insertion site of the mini-implants has an important role when intrusion of four maxillary incisors is considered and it can affect the results and outcomes of the treatment was proven by the following findings:
1) The different total maxillary incisors intrusion amount was found when a different insertion sites were used.
2) The treatment duration was found to be different when different insertion sites was used.
3) The force required to apply was found to be different when different insertion site was used.
In addition, by this systematic review we can conclude that:
The best results and outcomes achieved when one mini-implant was inserted between the maxillary central incisors. In case that two mini-implants were inserted in U2-U3 area: the bigger the force and the longer the duration of treatment was performed, a smaller mean of intrusion per month was observed. In contrast, when mini-implant was inserted in posterior region: U5-U6, a bigger force was needed for a bigger amount of total intrusion. However, when mini-implant was inserted in the U1-U2 site, any addition of applied force made no differences on the mean of intrusion per month.
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PRACTICAL RECOMMENDATIONS
- In order to treat deep overbite and/or gummy smile with MI, it is recommended to insert one mini implant between central incisors, 4mm superior to the free gingival margin, a load of 50g on each MI and plan a treatment schedule for at least 4 months.
- To reduce the risk of failure it is recommended to insert 2 MI between the lateral incisors and the canines, load each MI with not more than 40g of force and plan a treatment schedule of 4 months.
- Only for a better visual esthetics during the treatment and to the preference and request of the patient it is recommended to insert 2 MI in between 2nd premolar and 1st molar, load
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ANNEXES
Annex 1: Risk of bias assessment: MINORS with modification
Chandrase kharan D. et al.2010 Sachin P. et al. 2014 Polat-Ozsoy O. et al. 2009 Sensk N. et al. 2012 Ravindra-Kumar J. et al. 2014 Prasanna K. et al. 2017 Alaty M. 2015 Aras I. et al. 2016 a clearly stated aim 2 2 2 2 2 2 2 2 inclusion of consecutive patients 1 2 2 2 2 2 2 2 prospective collection of data 2 2 2 2 2 2 2 2 endpoints appropriate to the aim of study 2 2 2 2 2 2 2 2 unbiased assessment of the study endpoint 0 0 0 0 0 0 0 0 follow up period appropriate to the aim of the study 0 0 0 0 0 0 0 0 loss of follow up less than 5% 0 0 0 0 0 0 0 0 prospective calculation of
the study size 0 0 0 0 0 0 0 0
Statistical
Analysis 0 2 2 2 1 2 2 2
total 7 10 10 10 9 10 10 10
The items scored 0 (not reported), 1 (reported but inadequate) or 2 (reported and adequate). The total ideal score being 16.
