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Table of Contents
CASE REPORT
Year : 2016  |  Volume : 6  |  Issue : 2  |  Page : 69-74

Treatment of a Class II Division I malocclusion using miniscrews: A case report


Department of Orthodontics and Dentofacial Orthopedics, Mahatma Gandhi Missions Dental College and Hospital, Navi Mumbai, Maharashtra, India

Date of Web Publication15-Mar-2017

Correspondence Address:
Divij Dinesh Joshi
Smile Horizon, 13, Safal Ganga, Opp Sterling College, Near DMart, Sector-19, Nerul East, Navi Mumbai - 400 706, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0974-6781.202155

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   Abstract 

This case report describes the use of temporary anchorage devices for an 18-year-old Indian girl with a skeletal Class II malocclusion. Class II skeletal base indicating a vertical growth pattern with prognathic maxilla and orthognathic mandible in relation to the anterior cranial base, bilateral Angle's Class II molar and canine relationship with proclined and forwardly placed upper and lower incisors with an overjet of 7 mm and an overbite of 2 mm, and a convex soft tissue profile with an acute nasolabial angle and potentially competent lips. The treatment includes the extractions of the maxillary first premolars and mandibular second premolars, fixed appliance mechanotherapy, miniscrew-aided maxillary anterior retraction, and protraction of mandibular molars. The Angle's Class II Division I malocclusion, proclined upper and lower anteriors, overjet of 7 mm, and convex soft tissue profile with potentially competent lips were corrected. The crowding and rotation along with proclined incisors were corrected significantly improving patient's facial profile. The trending use of implants in orthodontics for everyday troublesome and complicated protocols is comparatively much efficient and quicker with the aids of mini-implants.

Keywords: Anchorage, implant, mini-implant, miniscrews


How to cite this article:
Joshi DD. Treatment of a Class II Division I malocclusion using miniscrews: A case report. J Dent Implant 2016;6:69-74

How to cite this URL:
Joshi DD. Treatment of a Class II Division I malocclusion using miniscrews: A case report. J Dent Implant [serial online] 2016 [cited 2017 Jun 22];6:69-74. Available from: http://www.jdionline.org/text.asp?2016/6/2/69/202155


   Introduction Top


Dental implant anchorage has progressed from nonintegrated screws (1940s)[1] to osseointegrated devices (1972 to present). Almost 60 years ago, the first orthodontic temporary anchorage device (TAD) was placed in the mandibles of dogs. Gainsforth et al. placed cobalt-chromium alloy (Vitallium) screws in the mandibles of dogs as anchors for the application of orthodontic forces.[2] The first clinical report of implant anchorage was in 1969 by Dr. Leonard Linkow.[3] TADs such as the mini-implant have proven efficacy in providing “absolute anchorage” in orthodontics.

TADs have developed into important orthodontic adjuncts for expanding the scope of biomechanical therapy and enhancing clinical outcomes.[4],[5] Most miniscrew and minscrew systems currently used in orthodontics are not designed for osseous integration (osseointegration); hence, they are called as TADs. TADs are placed with no long-term functional or esthetic role being planned. All TADs are invasive devices and are best reserved for problems that cannot be effectively managed with conventional mechanics. At present, the most common TADs include minscrews, microscrews, miniature implants (mini-implants), palatal implants, modified bone plates, and retromolar implants as well as functionally loaded prosthetic implants. Most current miniscrews are titanium (Ti) or Ti alloy and are manufactured with a smooth, machined surface that is not designed to osseointegrate.[6]

Before delving into the “how to” aspect of miniscrews, it might be useful to examine some properties of miniscrews. The three basic parts of a miniscrew are head, transgingival collar, and threaded shaft.

Size

A typical diameter of available miniscrews varies between 1.2 and 2.3 mm, a measurement that normally refers to the external diameter. The length of the miniscrews varies between 4 and 15 mm. Although this dimension normally refers to the length of the threaded shaft, some manufacturers' reference the total length of the screw (i.e., shaft, transmucosal collar, and head). Since miniscrews are often placed between roots, the amount of interradicular space is crucial in determining the insertion site. A 1:1 ratio of the length of the head of a miniscrew (portion outside the bone) to the threaded shaft (portion held within the bone) is preferred.[7]

Head

The “head” is often considered one of the most important aspects of the miniscrews. The head design must be applicable to a particular clinical situation. Different elements of the orthodontic mechanism (e.g., elastic chain, coil springs, auxiliaries, sectional, and continuous arch wires) are attached to the head of the screw.[8] The basic types of heads available are screw with hook, screw with ball head, screw with hole through the head, screw with simple slot, and screw with cross-slot. Many combinations of these designs are also available.

The transgingival collar

The transgingival (also transmucosal) collar or neck is the sensitive part of implants and miniscrews. Any perforation in the soft tissue provides a potential entry point for microorganisms and could give rise to inflammation or infection (perimucositis, periimplantitis),[9] often resulting in premature loss of miniscrews.[10] The typical thickness of the gingiva (according to Goaslind et al.[11] is on average, about 1.25 mm). According to Costa et al., the thickness varies from 1.4 to 4.2 mm depending on the region where it is measured.[12] The length of the transgingival collar for most miniscrews varies between 1 and 3 mm.

Shank and thread

For self-tapping screws, a pilot drill is used to remove osseous material. With self-drilling screws (i.e., no previous perforation of the corticalis with a pilot drill), space is created primarily by displacement of bone. This compression of bone contributes to the primary stability of the miniscrew.

In general, two different types of anchorage must be distinguished: direct and indirect. In a direct anchorage situation, the implant is directly connected to the dental unit(s) to be moved. When indirect anchorage is employed, the miniscrew stabilizes the dental anchorage unit, and an implant reinforced dental anchorage segment is the result. The introduction of miniscrew anchorage in orthodontics has signaled the start of a significant paradigm shift. Traditional orthodontic mechanics and treatment options may be substantially altered in many situations where more effective, efficient, and predictable TAD-supported directional forces could be used. The day will soon come when orthodontists will wonder how some treatments were ever accomplished without the advantage of miniscrew anchorage.

This case report describes the orthodontic treatment with the use of TADs for an 18-year-old Indian girl with a skeletal Class II malocclusion. The treatment includes extractions of the maxillary first premolars and mandibular second premolars, fixed appliance mechanotherapy, minscrew-aided maxillary anterior retraction, and protraction of mandibular molars. Pretreatment, midtreatment before space closure and space closure after retraction, and protraction using miniscrews and running loop, respectively, records are shown. The Angle's Class II Division I malocclusion, proclined upper and lower anteriors, overjet of 7 mm, and convex soft tissue profile with potentially competent lips were corrected. The crowding and rotation along with proclined incisors were corrected significantly improving patient's facial profile.


   Diagnosis Top


The patient was an 18-year-old Indian girl with the chief complaint that she had “crooked and forwardly placed upper front teeth.” The pretreatment facial photographs showed a convex facial profile with potentially competent lips and prominent incisors. The intraoral photographs showed Class II molar and canine relationship with rotated maxillary and mandibular incisors and an increased overjet [Figure 1].
Figure 1: (a) Pretreatment extra oral straight view. (b) Pretreatment extra oral three quarter view. (c) Pretreatment extra oral profile view. (d) Pretreatment intraoral straight view. (e) Pretreatment intraoral profile view. (f) Pretreatment intraoral maxillary view. (g) Pretreatment intraoral mandibular view

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The model analysis indicates crowding of 7 mm in maxilla and 6 mm in mandible. Bolton's analysis indicates a maxillary excess in the anterior and overall ratio. The overjet is +7 mm, curve of Spee is 2 mm, and an overbite is +2 mm.

The cephalometric analysis [Table 1] showed a skeletal Class II relationship (ANB angle: +5°) with slight maxillary prognathism and a vertical growth pattern (FMA: 32°). The maxillary and mandibular incisors were proclined (U1-NA: 36°, L1-NB: 28.5°) and forwardly placed (U1-NA: 9 mm, L1-NB: 7 mm) reducing the interincisal angle (interincisal angle: 114°) and an acute nasolabial angle (nasolabial angle: 80°).
Table 1: Cephalometric comparison of pretreatment values with post space closure

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The patient was diagnosed with Class II skeletal base indicating a vertical growth pattern with prognathic maxilla and orthognathic mandible in relation to the anterior cranial base, bilateral Angle's Class II molar and canine relationship with proclined and forwardly placed upper and lower incisors with an overjet of 7 mm and an overbite of 2 mm, and a convex soft tissue profile with an acute nasiolabial angle and potentially competent lips.


   Treatment Objectives Top


The orthodontic treatment aimed to correct the dental proclination and crowding increased overjet, Class II molar and canine relationship, and convex profile. Retraction of the maxillary and mandibular incisors would help correct the slight skeletal and required dental corrections.


   Treatment Progress Top


After extraction of the maxillary first premolar and mandibular second premolar, both arches were bonded and aligned with sequential nickel-Ti (NiTi) archwires. Active lacebacks were given from the molar to the canine during the initial stages. A miniscrew implant (Denticon, India) 1.6 mm × 8 mm was inserted interdental between the second premolar and first molar in the maxillary arch on each side [Figure 2]. An elastomeric chain (American Orthodontics, Wisconsin, USA) was applied from the miniscrew to distalize the maxillary anterior segment after consolidating the segment from the upper right canine to the upper left canine with a stainless steel ligature wire (American Orthodontics, Wisconsin, USA) on an upper 0.019 × 0.025 inch stainless steel archwire (G&H Orthodontics, Franklin, USA). Running loop was designed on a lower 0.017 × 0.025 inch stainless steel archwire (G&H Orthodontics, Franklin, USA) with loops distal to the mandibular first premolar and placed with an elastomeric chain which was extended from the hook on the molar tube on each side of the mandibular first molar onto the loop to aid in protraction of the first molar in achieving an Angle's Class I molar relationship [Figure 2].
Figure 2: (a) Preretraction intraoral straight view. (b) Preretraction intraoral profile view. (c) Preretraction intraoral maxillary view. (d) Preretraction intraoral mandibular view

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Postretraction of the maxillary anterior segment and protraction of the mandibular first molar, a normal incisor overjet and overbite were achieved with proper alignment and leveling of the arches in a Class I molar and canine relationship.


   Treatment Results Top


The case showed improvements of the lower third of the facial profile. The upper lip was significantly retracted correcting the incompetent lips and acute nasolabial angle. The soft tissue profile changed considerably from a convex to a straight profile. Dental crowding in both arches was alleviated. The increased overjet was corrected. The occlusion was improved to achieve Class I molar and canine relationships on both sides [Figure 3].
Figure 3: (a) Postretraction extra oral straight view. (b) Postretraction extra oral three quarter view. (c) Postretraction extra oral profile view. (d) Postretraction intraoral straight view. (e) Postretraction intraoral profile view. (f) Postretraction intraoral maxillary view. (g) Postretraction intraoral mandibular view

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From the postspace closure cephalometric analysis, upper incisor to A-Pog line has reduced severely from 12 to 4 mm (mean, −1–5 mm) and the N perpendicular to point A has reduced form −4 to −2 mm (mean, 0 ± 2 mm) while the lower incisor to mandibular plane has reduced from 2° to −5° (mean, −8.5°–7°). The mandibular plane of Steiner (Go-Gn) to SN has reduced as well from 34° to the idea 32° (mean 32°). The Wits appraisal which prevails the skeletal base reduced from the pretreatment values of +5–+2 mm (mean, −2–+2 mm). The basal plane angle (palatal plane to mandibular plane) has reduced from 30° to 27° (mean 25°) angle upper incisor to NA has decreased to 10° and 4 mm. The lower incisor to NB has dropped as well to 15° and 4 mm. While ANB angle has reduced to a +4° from a +5°. Significant changes appeared in the soft tissue profile correction of the acute nasolabial angle of 80° to a much more esthetical 95° [Table 1].


   Discussion Top


An 18-year-old Indian female presenting with a skeletal Class II base and a convex soft tissue profile with potentially competent lips on clinical examination and later with the help of diagnostic aids presented with the definite likelihood of extraction of premolars in both the maxillary and the mandibular arch to aid in the correction of the problem list, skeletal, dental, and soft tissue. In the maxillary arch, the first premolars were extracted bilaterally, correction of the rotations and crowding along with retraction of theproclined and forwardly placed upper incisors along justified the need for extractions.[13] The crowding in the mandibular arch along with the proclination of the incisors justified the need for extraction, relieving of the crowding, and alignment of the mandibular arch along with achieving a proper Class I canine relationship, with the remaining space to be utilized with the protraction of the mandibular molar to achieve a proper Angle's Class I molar relationship justified the need to extract the mandibular second premolar bilaterally.

After the initial NiTi archwires for leveling and aligning, the arches by de-crowding and de-rotating the teeth miniscrew for retraction of maxillary anterior segment, and a running loop was designed for protraction of the mandibular posterior segment. The use of critical anchorage was necessary in this case as the maxillary molar position (U6-PTV) was within normal. Anchor loss during retraction of the anterior segment could not be accepted, which meant to hold the molar into position without allowing any mesial movement or anchor loss during the phase of the treatment. If the maxillary molar drifted mesially during the treatment, the extraction space which was meant to be utilized for de-crowding and retraction of the severely proclined and forwardly placed incisors would become difficult to correct leaving with an excessive overjet. The use of a miniscrew in such cases eases the operators need for modifying anchorage by other more sophisticated appliances and technique.[14] A much simpler, quicker, and hassle-free procedure is accomplished.

A self-tapping miniscrew incision-free method applied after making a punch marking on the attached gingival (Denticon, India) 1.6 mm × 8 mm was inserted interdentally between the maxillary second premolar and first molar in a 60°–70° angulation.[15] Running loop was designed on a lower 0.017 × 0.025 inch stainless steel archwire with loop placed just distal to the first premolar to help consolidate the anterior segment along with figure of eight stainless steel ligature wire from the first premolar on the right-hand side to the first premolar on the left-hand side. The posterior section of the archwire distal to the loop was modified at an angulation to place toe in and tip back on the archwire for bodily movement of the mandibular molar by avoiding rolling in and rotation during its protraction.[16] An elastomeric chain was placed from the head of the implant to the hook of the canine bracket after consolidating the anterior segment with a figure of eight stainless steel ligature wire [Figure 2]. Another elastomeric chain was placed from the hook on the molar tube to the loop on the archwire distal to the first premolar bracket [Figure 2]. The elastomeric chain was changed frequently every 3–4 weeks for 4 months.

Postretraction of the maxillary anterior segment and protraction of the mandibular first molar [Figure 4], a normal incisor overjet and overbite were achieved with proper alignment and leveling of the arches. The rotations and crowding in each of the arches were eliminated along with the curve of Spee. The 7 mm overjet was reduced tremendously. The soft tissue profile improved tremendously, the convex profile drastically transformed to a straight profile postretraction of maxillary anteriors. The potentially competent lips and acute nasiolabial angle improved developing into competent lips with a much more pleasing nasiolabial angle. Finishing and detailing, the last stage in the treatment of this case is still pending which will be aimed at correcting the end-on canine relationship into a Class I canine relationship with the aid of Class II intraoral elastics. The intra-oral Class II elastics will also help achieve a much superior Class I molar relationship allowing minor incisor proclination which is desired at the current phase.
Figure 4: (a) Superimposition of maxilla and maxillary teeth (pretreatment in red and postretraction in green). (b) Superimposition of mandible and mandibular teeth (pretreatment in red and postretraction in green). (c) Superimposition of soft tissue profile with the skeletal bases and teeth (pretreatment in red and postretraction in green)

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Miniscrews are used in orthodontics not only to aid in critical anchorage situations with retraction like the represented case but can also be used for intrusion of segments and with the help of more than one, even the entire dentition. Implants are also helpful in cases of distilization as there generally is no form of support present for the attachments distal to the molars. Expansion of constricted arches with the help of implants rather than much bulkier and bothersome appliances is a sanctification in its own form.[17] Mini-implants can simplify the treatment plan and provide absolute anchorage for the distal movement of buccal teeth in a group as well as maximum retraction of the anterior teeth.[18]


   Conclusion Top


It appears that in the near future, miniscrews will become a routine part of daily clinical orthodontic practice as a conservative means of temporary skeletal anchorage. The paradigm has shifted with the trending and smart use of implants in orthodontics for everyday troublesome and complicated protocols which are now more efficient, easier, and less time-consuming for every clinician day-after-day.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
   References Top

1.
Roberts WE, Smith RK, Zilberman Y, Mozsary PG, Smith RS. Osseous adaptation to continuous loading of rigid endosseous implants. Am J Orthod 1984;86:95-111.  Back to cited text no. 1
    
2.
Gsindforth BL, Higley LB. A study of orthodontic anchorage possibilities in basal bone. AM J Orthod 1945;31:406-17. Available from: http://www.ajodo.org/article/0096-6347(45)90025-1/abstract.  Back to cited text no. 2
    
3.
Linkow LI, Chercheve R. Theories and Techniques of Oral Implantology. St. Louis: Mosby; 1970.   Back to cited text no. 3
    
4.
Roberts WE, Marshall KJ, Mozsary PG. Rigid endosseous implant utilized as anchorage to protract molars and close an atrophic extraction site. Angle Orthod 1990;60:135-52.  Back to cited text no. 4
    
5.
Janssens F, Swennen G, Dujardin T, Glineur R, Malevez C. Use of an implant as orthodontic anchorage. Am J Orthod Dentofacial Orthop 2002;122:566-70.  Back to cited text no. 5
    
6.
Nanda R, Uribe FA. Endosseous miniscrews: Historical, vascular, and integration perspective. Temporary Anchorage Devices in Orthodontics. New Delhi: Mosby; 2009. p. 3-13.  Back to cited text no. 6
    
7.
Ludwig B, Baumgaertel S, Bowman SJ. Mini-screws – Aspects of assessment and selection among different systems. Mini-Implants in Orthodontics, Innovative Anchorage Concepts. New Delhi: Quintessence; 2008. p. 20-1.  Back to cited text no. 7
    
8.
Ludwig B, Baumgaertel S, Bowman SJ. Mini-screws – Aspects of assessment and selection among different systems. Mini-Implants in Orthodontics, Innovative Anchorage Concepts. New Delhi: Quintessence; 2008. p. 23.  Back to cited text no. 8
    
9.
Hobkrik J, Watsonn RM, Searson L. Introducing Dental Implants. Edinburgh: Churchill Livingstone; 2003.  Back to cited text no. 9
    
10.
Park HS, Jeong SH, Kwon OW. Factors affecting the clinical success of screw implants used as orthodontic anchorage. Am J Orthod Dentofacial Orthop 2006;130:18-25.  Back to cited text no. 10
    
11.
Goaslind GD, Robertson PB, Mahan CJ, Morrison WW, Olson JV. Thickness of facial gingiva. J Periodontol 1977;48:768-71.  Back to cited text no. 11
    
12.
Costa A, Pasta G, Bergamaschi G. Intraoral hard and soft tissue depths for temporary anchorage devices. Semin Orthod 2005;11:10-5.  Back to cited text no. 12
    
13.
Kim TK, Kim JT, Mah J, Yang WS, Baek SH. First or second premolar extraction effects on facial vertical dimension. Angle Orthod 2005;75:177-82.  Back to cited text no. 13
    
14.
Roberts WE, Helm FR, Marshall KJ, Gongloff RK. Rigid endosseous implants for orthodontic and orthopedic anchorage. Angle Orthod 1989;59:247-56.  Back to cited text no. 14
    
15.
Wilmes B, Su YY, Drescher D. Insertion angle impact on primary stability of orthodontic mini-implants. Angle Orthod 2008;78:1065-70.  Back to cited text no. 15
    
16.
Chae JM. Treatment of class II malocclusion with bialveolar protrusion by means of unusual extractions and anchorage mini-implant. Dent Press J Orthod 2012;17:165-77.  Back to cited text no. 16
    
17.
Herman R, Cape J. Temporary anchorage devices in orthodontics; mini-implants. Semin Orthod 2005;11:32-9.  Back to cited text no. 17
    
18.
Chae JM. Treatment of class II malocclusion with bialveolar protrusion by means of unusual extractions and anchorage mini-implant. Dent Press J Orthod 2012;17:165-77.  Back to cited text no. 18
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]
 
 
    Tables

  [Table 1]



 

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