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Authors: Dr. Snigdha Gowd, Dr. T Shankar

ABSTRACT:

Paradigms have started to shift in traditional orthodontic world since the introduction of mini implants in as the anchorage. Mini screws have allowed the management of wider discrepancies than those treatable by conventional bio mechanics, because force can be applied directly from bone borne anchor units. This article describes about a mesioangularly impacted mandibular second molars. Impacted mandibular molar often acts as challenge to the orthodontist because of the density of the bone in the posterior area and the force required to upright a molar is more hence it is ideal to have an appliance that acts as a rigid support and doesn’t cause any reciprocal changes on the Anchor teeth. The introduction of mini implants for uprighting of molars has become easy. The third molar was extracted to give space to upright the second molar by using a Mini Implant.

KEYWORDS:

Skeletal Anchorage, Uprighting of Molars, Impaction, Molar Distalization.

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  • CASE REPORT

    A 13 year old female presented with a chief compliant of proclined upper front teeth and a protrusive profile and incompetent lips and dissatisfied with her smile. On clinical examination it revealed that she had bimaxillary protrusion with a class I molar relation on the right side and a class I molar relation on the left side with a convex profile and an increased overjet and an increased overbite. Her 2nd Molar on the Lower right side was missing but her left lower second molar had erupted. Patient’s oral hygiene was fair and periodontium was healthy. See fig1, fig2, fig3.

    Fig.5 Fig.6
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    Radiographic analysis

    Cephalometric analysis showed a bimaxillary protrusion with SNA-92 and SNB-87 and ANB-5 indicated a normal growth pattern. Her panoramic radiographs showed that she had a mesioangularly impacted right 2nd molar 47 and the 3 rd molar 48 was also mesioangularly impacted on top of it.

    Treatment goal

    The treatment goal was to improve the patients smile and de crowd the lower anteriors and maintain a class I molar relation and improve the periodontal healthy and upright the mesioangularly impacted 47. See fig8, fig9, fig10.

    Treatment plan

    After evaluating it was decided that she required extraction of 14, 24, 34, 44 for correcting her bimaxillary protrusion and relieving the crowding in the lower anteriors. It was also decided to extract the 48 and upright 47 by using either uprighting springs or mini implants. After extracting the 3 rd molar the second molar was partially visible and in the oral cavity placing a band on a molar was difficult. So a bonded buccal tube was placed. The force applied by an uprighting spring is 60 n forces and there would be reciprocal forces on the lower anterior, this appliance will allow the second molar to extrude and open the bite depending on the flexibility of the arch wire. The continued leveling of the arch with larger arch wires may intrude the uprighted molar sufficiently to avoid occlusal equilibration. According to Daniel fernado et al1 there was no significant

    Fig.7 Fig.8
    Fig.7 Fig.8

    differences were found between the uprighting springs made of Australian wire and domestic wire, uprighting spring pins force produced higher forces initially than commonly designed uprighting springs, force values vary inversely with the degree of bracket angulation. The density of bone on the mandible would be more and the force required to upright the lower molar was more so it was decided to use a micro implant as the force applied by a skeletal anchorage was more than 120 n force as said by Kim Roberts et al2 Describe the use of rigid osseous fixation using Titanium Screws. The endosseous implant remained rigid despite of continues applied load. So it was decided to use a mini implant. See fig11, fig12, fig13

    Treatment progress

    The upper and lower anterior were bonded using a straight wire brackets using dentarum kit with 022 slot .the arches were aligned with initial stages of wires of 014 followed by 016, 018 ,020 wires than patient was shifted on the 17x25 cu Nitti wires. A dentos Micro Implant was placed in the region of 48 size of 8mm and 1.5mm diameter. The Mini Implant was inserted parallel to the tooth axis in an edentulous area. The lower arch was completely ligated together from 36 to 46 and a chain was placed from 47 to micro implant, after uprighting 47 than the O16 NITI wire was placed to get it into occlusion, Than 47 was bonded with a bonded buccal tube and e chain was placed in relation to the from 47 to mini implant 48 the e chain was changed after every 3 weeks within a period of 5 weeks the tooth was uprighted as the force was from a bone borne anchor there was no change in position of the lower anteriors. See fig 14, 15, 16, 17

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    Discussion

    Distalization of the molars has been one of the most difficult biomechanical problems in traditional orthodontics, particularly in adults and in the mandible. However, it has now become possible to move molars distally with the SAS to correct anterior cross bites, maxillary dental protrusion, crowding, and dental asymmetries without having to extract premolars. The skeletal anchorage system (SAS) consists of titanium anchor plates and monocortical screws that are temporarily placed in either the maxilla or the mandible, or in both, as absolute orthodontic anchorage units.

    The first case of molar distalization was published in 1985 by Jenner and Fitzpatrick3. A bone plate was inserted into the ramus and direct traction was applied to distalize a lower first molar by 3.5mm in 5 months.

    Junji Sugawara et at4 conducted a study to distalize molars using skeletal anchorage system which consisted of titanium anchor plates and monocortical screws that are temporarily placed in either the maxilla or the mandible and evaluated the treatment changes during and after distalization of mandibular molars. Study evaluated the treatment and post treatment changes during and after distalization of the mandibular molars. In 15 adult patients (12 women and 3 men), a total of 29 mandibular molars were successfully distalized with SAS. The amount of distalization and relapse and the type of tooth movement were analyzed with cephalometric radiographs and dental casts. The average amount of distalization of the mandibular first molars was 3.5 mm at the crown level and 1.8 mm at the root level. The average amount of relapse was 0.3 mm at both the crown and root apex levels. Of 29 mandibular molars, 9 were tipped back, and the others were translated distally in accordance with the established treatment goals. SAS is a viable modality to move mandibular molars for distally correcting anterior cross bites, malocclusions characterized by mandibular anterior crowding, and dental asymmetries.

    In 2005 Yun et al5 assessed the use of miniscrews for indirect anchorage to upright two cases of mesial tipped madibular second molar this setup in which a rectangular stain less steel wire connected the screw and the anchor teeth uprighted the molars with out unwanted movement in the reinforced anchor teeth. In 2006 Sugawaral et al6 published an other study comprising of 25 nongrowing patients treated with a mini plate system to distalize the maxillary first molar after the extraction of either the second or third maxillary molars. The mean amount of distalization was 3.78 mm at crown level and 3.20 mm at root level.

    Lee & Chung7 demonstrated the effect of early loading in the osseous integration of the prototype of the C-implant in animal experiments. They showed that there was no significant difference between immediate loaded implants and unloaded implants. The pre mature loaded after a four week healing period did not halt the progress of osseous integration between the bone and implant.

    Aldo Carno et al8 said Molar Distalization using : Miniscrews and Distal jet may be a solution. After the distal jet appliance has been placed and activated, palatal miniscrews are inserted between the roots of the first and second premolars, mesial to the activation locks attached to the anterior rests. The miniscrews block mesial movement of the appliance during distalization, thus preventing loss of anterior anchorage.

    Fig.11 Fig.12
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    Conclusion

    The use of skeletal anchorage not only changed how far teeth can be move but also offered more treatment options to patients. Orthodontic Camouflage of mal occlusion which needs surgical corrections becomes possible to achieve with out surgery by skeletal anchorage. The introduction of mininscrews and miniplates into orthodontics has had a revolutionary impact on the specialty. Uprighting of mandibular molars was never an easy task to accomplish with out unwanted tooth movement on the reinforced anchor teeth. Skeletal anchorage with Mini implant offers more options for patients and dentist to achieve betters results then ever before. Usage of mini implants for up righting of molars should be used quite frequently in our daily practice as it gives rigid osseous support, as it acts a skeletal anchorage, takes less time, and does not cause any unwanted tooth movement in the reinforced anchored teeth is a less invasive procedure.

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    References:
    1. Daniel Fernando Ramos, Allan D Weimer, Millford Hanna. A study of the forces produced by various preformed uprighting springs. A.J.O Vol.76, issue – 6 Dec-1979 page 637-645
    2. Roberts W.E Smith, R.K.Zilberman, Y.Mozsary, PG & Smith. R.S Osseous Implants AM J.O – 86-95-111-1984
    3. Jenner Jd, Fitzpatrick BN: Skeletal anchorage utilizing bone plates. Aust Orthod J 9:231, 1985
    4. Junji sugawara. A bioefficient skeletal anchorage System. biomechanics and esthetic strategies in clinical ortho dontics, 2004, 295 – 309
    5. Yun SW, Lim WH, Chun YS: Molar control using indirect miniscrew anchorage. J Clin Orthod 39:661, 2005.
    6. Sugawar J, Kanzaki R, Takahashi I et al. Distal movement of maxillary molars in non growing patients with skeletal anchorage systems. Am J Orthod DentoFacial Orthop 129:723, 2006
    7. Lee S.J. K.R Chung, The effect of early Loading on the direct bone to implant surface contact of the orthodontic Osseo integrated Titanium Implant Korean J.Orthodont 2001-31-173-18
    8. Aldo carano, Stefano velo, paola Leone, Giuseppe siciliani Clinical applications of the miniscrew anchorage system. Journal clin orthod 2005; 29:9-24

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