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Table of Contents
Year : 2021  |  Volume : 9  |  Issue : 4  |  Page : 115-118

Comparison of anchorage from mini-implant and conventional anchorage methods to retract anterior teeth: An original study

1 Department of Orthodontics and Dentofacial Orthopaedics, Aditya Dental College and Hospital, Beed, India
2 Department of Orthodontics and Dentofacial Orthopaedics, Yogita Dental College and Hospital, Khed, India
3 Department of Orthodontics and Dentofacial Orthopaedics, Dr. H.S.R.S.M. Dental College and Hospital, Hingoli, Maharashtra, India

Date of Submission18-Oct-2021
Date of Acceptance07-Nov-2021
Date of Web Publication27-Dec-2021

Correspondence Address:
Dr. Ranjit Omprakash Pawar
Department of Orthodontics and Dentofacial Orthopaedics, Aditya Dental College and Hospital, Sarda Estate, Pimpalner Road, near Nalwandi Naka, Beed 431122, Maharashtra.
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/INJO.INJO_34_21

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Background: Proclined teeth has been one of the main reasons for compromised esthetics. In a patient with proclined anteriors, retraction is performed after first premolar extraction. Absolute/maximum anchorage is required to achieve the best esthetics. Aims and Objectives: We conducted this study with the aim of retracting the proclined maxillary anterior teeth and to check for efficient retraction, type of tooth movement during retraction, and amount of anchorage loss. Materials and Methods: Patients with proclined anterior teeth where therapeutic extraction of first premolars is required were included in the study, where anchorage was taken with mini-implants in one group, and in the second group, conventional anchorage method of first and second molar banding with transpalatal arch was chosen. Each group consisted of 25 subjects. Lateral cephalogram was taken both pre-retraction and 6 months after starting retraction to compare anchor loss, rate of retraction, and type of tooth movement of retracted anteriors in both groups. Results: The retraction in the implant group was more than in the conventional group and the difference was statistically significant (P < 0.05). Anchorage loss was seen to be greater in conventional group than in the implant group and was found to be statistically significant as well. The type of tooth movement of the anterior teeth on retraction was also compared, with the implant group showing predominantly controlled tipping and the conventional group showing uncontrolled tipping movement.

Keywords: Anchorage loss, anterior teeth, mini-implants, proclination

How to cite this article:
Pawar RO, Patil CD, Mahajan S, Khan R, Chavan A, Jadhav S. Comparison of anchorage from mini-implant and conventional anchorage methods to retract anterior teeth: An original study. Int J Oral Care Res 2021;9:115-8

How to cite this URL:
Pawar RO, Patil CD, Mahajan S, Khan R, Chavan A, Jadhav S. Comparison of anchorage from mini-implant and conventional anchorage methods to retract anterior teeth: An original study. Int J Oral Care Res [serial online] 2021 [cited 2022 Jan 19];9:115-8. Available from: https://www.ijocr.org/text.asp?2021/9/4/115/333815

  Introduction Top

Every type of tooth movement, irrespective of the (fixed or removable) orthodontic appliance involved, generates an equal and opposite reactive force, as first described by Newton’s third law of motion. Anchorage (reinforcement) comprises a myriad of clinical approaches to reduce the negative effects of this reactive force, which manifests clinically as anchorage loss. One of the major concerns in orthodontic patients is facial esthetics. Also, patients demand fast treatment time that does not stretch to years and does not require constant oral hygiene care. This would improve oral health, and overall well-being, without causing any burnout from long treatment times. Better esthetics also provide increased confidence in young adults. Protrusive upper lip is seen in cases with protrusion of maxillary teeth in Angle’s Class II division I malocclusion and Class I bimaxillary protrusion.[1],[2],[3],[4],[5] Such cases require therapeutic first premolar extraction, and ideally, the anterior teeth are retracted completely without any inadvertent reactionary mesial molar movement. In a traditional approach, extraoral appliances (headgear, facemask) or intaoral aids (transpalatal arch, nance holding arch, multiple teeth as anchor segments) have been used, but not without disadvantages such as unfavorable reactionary tooth movements and patient compliance. To overcome these limitations, temporary anchorage devices (TADs) that get anchored in bone came into being. They can be used for direct anchorage or can help support posterior teeth that form anchorage unit (indirect anchorage).[5],[6],[7],[8],[9],[10],[11] In this study, comparison in treatment effects of retraction using two methods of anchorage, that is, mini-implant and conventional methods, in cases where anterior retraction is needed in the first premolar extraction space (Angles Class II division I or Angles Class I with bidentoalveolar protrusion), using sliding mechanics.

  Materials and Methods Top

Amount of retraction and anchor loss with type of tooth movement seen in a 6-month interval was recorded. A prospective clinical trial was performed in the Department of Orthodontics and Dentofacial Orthopedics. All procedures performed in the study were conducted in accordance with the ethical standards given in the 1964 Declaration of Helsinki, as revised in 2013. The study proposal was submitted for approval and clearance was obtained from the ethical committee of our institution. Written informed consent was obtained from each participant. Fifty subjects were enrolled and put in two different groups of 25 each. After sampling, implant group (Group 1) consisted of 11 men and 14 women (mean age 19.87 years) and the conventional group (Group 2) consisted of 10 men and 15 women (mean age of 22.25 years). Preadjusted edgewise 0.022′′ slot MBT appliance was chosen, and banding of molars was performed. Retraction was performed on a 19 × 25 SS wire engaged passively. At this stage, pre-retraction records including lateral cephalogram, OPG (Orthopantomagram), study models, extraoral, and intraoral photographs were taken and repeated after 6 months of retraction. Anterior and posterior segments were consolidated separately and retraction nickel-titanium (NiTi) coil spring was attached to the anchor source at one end and power arm at the other end.

For Group 1 (implant group) patients, the site between the second premolar and first molar was selected for the placement of implants on either side. For Group 2, conventional anchorage methods were used. After leveling and alignment, when a passive 19 × 25 SS wire was reached, the posterior teeth were joined together to form the buccal stabilizing segment, which included the second premolar, first molar, and second molars.

To check for changes in position of the central incisors, the quotient of the moved distance of the most apical point (Ia) and the moved distance of the most occlusal point (Io) was calculated. A negative sign was allotted to the amount, if the apical point moved in the opposite direction to the coronal point or vice versa. Classification of tooth movement was performed as follows (Ia/Io): <0, uncontrolled tipping; =0, controlled tipping; >0, controlled tipping and bodily movement; 1, bodily movement; and >1, root movement. The numbers and percentages of the three types of tooth movement were calculated and assessed. Data were analyzed by using the Statistical Package for the Social Sciences (SPSS) software program, version 20.0 (Chicago, Illinois). Mean and standard deviation were calculated for all values obtained from the lateral cephalogram. A paired sample t test was used to measure the treatment changes in the implant and conventional group. Independent-samples t test was used to compare mean treatment changes among the two groups. Level of significance was set as P < 0.05.

  Results Top

In the implant group, the molar showed, though insignificant, net distal movement of –0.29 ± 0.80 mm on mesial and –0.27 ± 0.82 mm on the distal aspect of the molar. But conventional group showed a highly significant mesial movement of 1.35 ± 0.41 mm on mesial and 1.18 ± 0.37 mm on distal. A statistically significant difference was observed between the groups (P < 0.05) [Table 1]. Vertically, the molar showed a net intrusion of –0.59 ± 0.65 mm on mesial and –0.67 ± 0.99 mm on distal, but some extrusion was also seen in implant group. However, the conventional group showed extrusion.
Table 1: Comparison of incisor movement in the sagittal plane

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The implant group showed net distal molar tipping of 0.57 ± 2.07 (anchor gain), whereas the conventional group showed significant mesial tipping of –2.25 ± 1.22 (anchor loss).

Movements of maxillary incisor

The amount of retraction of incisor was significantly larger in the implant group (–6.0 ± 1.18 mm) than in the conventional group (–3.11 ± 0.42 mm).

The incisal root apex moved distally slightly in implant anchorage (–0.61 ± 0.94 mm) but crown moved distally showing predominantly controlled tipping of incisors. But the conventional group apex moved mesially (+0.5 ± 1.39 mm) and crown moved distally causing uncontrolled tipping.

Vertically, the maxillary incisor apex showed significant intrusion of –1.0 ± 0.75 mm in the implant group, but incisal edge intruded to a lesser extent (–0.53 ± 1.05 mm). The conventional group showed significant incisal extrusion. Therefore, the difference in the intergroup was statistically significant.

The incisal proclination (I Angle) decreased by –11.29 ± 3.45° in the implant group and by –7.59 ± 3.81° in the conventional group.

Rate of retraction

Retraction achieved with implants in 6-month duration was 5.0 mm (1.27 mm/month) and 3.155 mm (0.79 mm/month) in the conventional group.

Type of tooth movement

The implant anchorage brought about controlled tipping with some translation (Ia/Io = 0.12 ± 0.19). The conventional group mostly showed uncontrolled tipping (Ia/Io= –0.13 ± 0.43). The intergroup differences were statistically insignificant [Table 1].

The implant group showed controlled tipping of 64%. Some uncontrolled tipping of 36% with bodily movement was also seen [Figure 1]. This movement was higher in percentage than the conventional group. The conventional group mostly showed uncontrolled tipping of 80% and controlled tipping of 20%.
Figure 1: Controlled tipping in the implant group

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  Discussion Top

Patients seek orthodontic treatment to improve their esthetics, which leads to greater psychological well-being. No implant failure was encountered in our study; hence, the success rate was 100%. Greater incisor retraction in the implant group could be attributed to the fact that retraction of only the incisors occurred without mesial molar movement, whereas in the conventional group molars moved mesially with decreasing the retraction force magnitude. This finding was similar to the results seen in the study performed by Thiruvenkatachari et al.[5] where canine retraction proceeded at a faster rate in the implant (4.29 mm) than in the conventional group (3.79 mm). Differences were highly significant at the apex and significant for the maxillary incisal edge between both the groups, as intrusion was more apparent at the apex in the implant group. Controlled tipping was the predominant tooth movement with implants. However, the conventional group showed predominantly uncontrolled tipping. According to Horiuchi et al.,[11] width of the alveolar bone and palatal cortical bone could be some of the limiting factors during orthodontic retraction. The width of the alveolar bone was adequate for all the patients. In a study by Edward,[8] it was found that bone remodeled with tooth movement at the level of mid-root and alveolar margins but not at higher levels. He inferenced that alveolar bone in the anteropalatal curve caused greater interference in the retraction of teeth. This could be the reason for limited distal apical movement in the implant group. Also, the forces were directed close to the center of resistance of the anterior segment, causing controlled tipping, which is preferred when teeth are highly proclined.

In the conventional group, mostly uncontrolled tipping was seen as the retraction force vector was predominantly horizontal and away from center of resistance of the anterior teeth. A clockwise movement was generated, causing lingual tipping and extrusion.

  Conclusion Top

It can be concluded that mini-implants provide a superior treatment result, be it in terms of efficient tooth movement, or anchorage control. Thus, they reduce the treatment duration, being of benefit to both the patient and orthodontist.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Upadhyay M, Yadav S, Patil S. Mini-implant anchorage for en-masse retraction of maxillary anterior teeth: A clinical cephalometric study. Am J Orthod Dentofacial Orthop 2008;134:803-10.  Back to cited text no. 1
Nanda R. Temporary Anchorage Devices in Orthodontics. St. Louis, MO: Mosby; 2008.  Back to cited text no. 2
Storey E, Smith R. Force in orthodontics and its relation to tooth movement. Aust J Dent 1952;56:11-8.  Back to cited text no. 3
Bobak V, Christiansen RL, Hollister SJ, Kohn DH. Stress-related molar responses to the transpalatal arch: A finite element analysis. Am J Orthod Dentofacial Orthop 1997;112:512-8.  Back to cited text no. 4
Thiruvenkatachari B, Ammayappan P, Kandaswamy R. Comparison of rate of canine retraction with conventional molar anchorage and titanium implant anchorage. Am J Orthod Dentofacial Orthop 2008;134:30-5.  Back to cited text no. 5
Basha AG, Shantaraj R, Mogegowda SB. Comparative study between conventional en-masse retraction (sliding mechanics) and en-masse retraction using orthodontic micro implant. Implant Dent 2010;19:128-36.  Back to cited text no. 6
Davis D, Krishnaraj R, Duraisamy S, Ravi K, Dilip S, Charles A, et al. Comparison of rate of canine retraction and anchorage potential between mini-implant and conventional molar anchorage: An in vivo study. Contemp Clin Dent 2018;9:337-42.  Back to cited text no. 7
[PUBMED]  [Full text]  
Edwards JG. A study of the anterior portion of the palate as it relates to orthodontic therapy. Am J Orthod 1976;86:43-51.  Back to cited text no. 8
Becker K, Pliska A, Busch C, Wilmes B, Wolf M, Drescher D. Efficacy of orthodontic mini implants for en masse retraction in the maxilla: A systematic review and meta-analysis. Int J Implant Dent 2018;4:35.  Back to cited text no. 9
Rajni N, Shetty S, Prakash AT. To compare treatment duration, anchor loss, and quality of retraction using conventional en-masse sliding mechanics and en-masse sliding mechanics using micro-implants. J Ind Orthod Soc 2010;44:52-61.  Back to cited text no. 10
Horiuchi A, Hotokezaka H, Kobayashi K. Correlation between cortical plate proximity and apical root resorption. Am J Orthod Dentofacial Orthop 1998;114:311-8.  Back to cited text no. 11


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  [Table 1]


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