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Mini-implant Aided Alignment of Horizontally Impacted Lower Second Molar A Case Report Salwa Jeragh Alhaddad – BChD, MFDS, RCSI, MSc Ortho, M’Orth RCSEng Ameri Dental Hospital – Kuwait – [email protected] Mashael Alnasser – BA, BDSc, MFDS, MGDS, RCSI Ameri Dental Hospital – Kuwait Manar Alnouri – BDS, MFDS, MGDS, RCS Ameri Dental Hospital – Kuwait ABSTRACT Aim: To present a contemporary method of aligning horizontally impacted teeth. Case presentation: A medically fit 17 year old female patient, presented to the orthodontic clinic with a horizontally impacted lower left second molar in an otherwise Class I occlusion with no aesthetic concerns. A two year history of the lower left third molar extraction in an attempt to normalize the lower left second molar’s path of eruption was reported by the patient with no evident success. Intervention: The patient was treated with a sectional fixed appliance on the lower left quadrant supported by a mini-implant temporary anchorage device in the left maxillary tuberosity region for inter-maxillary elastic wear. Successful alignment of the lower left second molar was achieved in a period of eleven months. Conclusion: The incorporation of mini-implants into orthodontic mechanics, has provided new limits to contemporary orthodontics, enabling orthodontists to align teeth that were previously considered common extraction candidates. KEYWORDS Mini-implants, Uprighting terminal molar, Horizontal impactions, Sectional fixed appliance. INTRODUCTION Horizontal impaction of the terminal molar tooth is a frequent problem orthodontists face in their daily practice, with the lower third molar being the tooth most frequently affected.1 Treatment lines ranged from accepting the problem and placing the patient under periodic reviews, to surgical extraction of the impacted tooth. To date orthodontic correction and alignment has been reserved for milder cases of impaction with sufficient eruption. During the past decade, however, the spreading use of temporary anchorage devices (TADS/ Mini-implants) has enabled orthodontists to expand their limits in terms of force magnitude and vectors necessary to correct more challenging cases.2 CLINICAL PRESENTATION A medically fit and healthy 17 year old female patient was referred to my clinic from the oral surgery department requesting a second opinion prior to the extraction of her horizontally impacted lower left permanent second molar. | 20 | Smile Dental Journal | Volume 7, Issue 3 - 2012 History taking revealed the extraction of the lower left third molar two years previously in an attempt to normalize the path of eruption of the lower left second molar, with no evident success. Extra Oral Examination Patient presented with a Class I skeletal pattern, average vertical proportions, no signs of skeletal or soft tissue asymmetry and healthy tempomandibular joints. Intra Oral Examination Patient presented with a Class I incisal, canine and molar relations, with average overjet, overbite (Fig. 1A) and minimal signs of crowding (Fig. 1B). Upper and lower midlines were coincident (Fig. 1A). The lower left second molar was partially erupted and horizontally impacted (Fig. 1B), in an otherwise normal occlusion. (Radiograph 1) Initial Orthopantomogram of the dentition (Fig. 1) A: Initial anterior view of the dentition. B: Initial lower occlusal view of the dentition SPECIAL TESTS Radiographic examination of the patient confirmed the presence of complete dentition except the lower left third molar. The lower left second molar was horizontally impacted with its occlusal surface paralleling the distal root surface of the lower left first molar (Radiograph 1). Both upper third molars and the lower right third molar were unerupted, with the latter being horizontally impacted (Radiograph 1). Cephalometric analysis confirmed the clinical findings of a Class I skeletal pattern with an element of bimaxillary proclination, rendered normal according to the patient’s racial group.3 (Radiograph 2) Initial lateral cephalogram TREATMENT OPTIONS Due to the partial eruption of the lower left second molar, it was explained to the patient that any treatment option that accepts the impaction would involve a significant risk of carious attack on both the lower left first and second molars. The option of extracting the second molar, however, shortens the dental arch and limits the occlusal table to the first molar rendering the upper left second and third molar non-functional. Therefore the use of a sectional fixed appliance mechanics in the lower left quadrant supported with a temporary anchorage device in the left maxillary tuborosiy region for inter-maxillary elastic, was proposed to the patient to upright the lower left second molar. Smile Dental Journal | Volume 7, Issue 3 - 2012 | 21 | Initial Periapical radiograph of the impacted lower left second molar 2 months progress periapical radiograph of the impacted lower left second molar Near end of treatment Periapical radiograph of the impacted lower left second molar (Fig. 3) A: Post treatment lower occlusal view of the dentition. B: Post treatment anterior view of the dentition in occlusion. C: Post treatment left view of the dentition in occlusion Aims & Objectives of Treatment • Maintaining the lower left second molar. • Distal uprighting and extrusion of the lower left second molar. • Preventing the supra-eruption of the upper left second molar. Treatment Plan A sectional fixed appliance on the lower left first and second premolars and first molar was bonded with the aid of a temporary anchorage device at the left maxillary tuberosity region for intermaxillary elastic wear. Initial distalization of the lower left second molar using NiTi push coil was carried out. This was followed by molar distal uprighting and extrusion with an intermaxillary elastic applied in a disto-vertical direction to the mini-implant, temporary anchorage device at the left maxillary tuborosity. (Fig. 2) A: 9 months progress of the lower dentition. B: 9 months progress of the left dentition in occlusion | 22 | Smile Dental Journal | Volume 7, Issue 3 - 2012 Treatment Progress Sectional fixed appliance mechanics were used to aid initial distalization and uprighting of the lower left second molar. This step was later supported with the use of a mini-implant, temporary anchorage device (of 8mm length and 1.4mm diameter by Ormco), placed in the left maxillary tuberosity region to provide a disto-vertical force vector as the patient wears an intermaxillary elastic (3/16” of 3.5oz by Unitek). The retention of TADs is mechanical in nature, which permits immediate or early loading and is, therefore, dependent on the length and diameter of the mini-implant used.5 The advantage of increasing the length and diameter must, however, be weighed against the increased risk of root damage to the neighboring teeth during placement. Chen et al. had found that; mini-implants of 1.2mm diameter and 8mm length offered a 90% success rate with minimal damage to the roots of neighboring teeth.5 This side effect can further be minimized by careful planning and radiographic examination of the target site.6 The alignment of the horizontally impacted terminal molar places a great challenge on classic treatment mechanics with limited force directions and magnitude. The use of mini-implant temporary anchorage devices has not only enabled orthodontists to align unfavorable impactions, but has also reduced the need for extra-oral anchorage devices (headgears) and the extractions of teeth that were previously considered with unfavorable path of eruption. (Fig. 4) A: First year review, of the lower dentition. B: First year review, of the anteriors in occlusion. C: First year review, of the left dentition in occlusion Nine months into treatment, the lower left second molar was sufficiently erupted (Fig. 2) and a bondable tube attachment (by American Orthodontics) was fixed to finalize the alignment of the tooth and detail the occlusion through the progression in archwire sequence (Fig. 3). The first annual review revealed stable results (Fig. 4). DISCUSSION Temporary anchorage devices can be placed using a simple surgical technique that can be performed by orthodontists, to gain a wider range of force in terms of magnitude and vectors.4 CONCLUSION The introduction of temporary anchorage devices has provided new limits to the practice of orthodontics enabling the alignment of teeth that were previously considered common extraction candidates. REFERENCES 1. O Breik, D Grubor. The incidence of mandibular third molar impactions in different skeletal face types, Aust Dent J. 2008;53(4):320-4. 2. Kanomi R. Mini-implant for orthodontic anchorage, J ClinOrthod. 1997;31:763-7. 3. Al-Azemi R and Artun J. Posteroanterior cephalometric norms for an adolescent Kuwaiti population, Eur J Orthod. 2012;34(3):312-7. 4. Adriano G. Crismani,aMichael H. Bertl,bAlesˇ G. Cˇ elar,aHansPeter Bantleon,aand Charles J. Burstonec. Mini-screws in orthodontic treatment: Review andanalysis of published clinical trials, AJODO. 2010;137(1):108-13. 5. Chen CH, Chang CS, Hsieh CH, Tseng YC, Shen YS, Huang YI et al. The use of mincroimplants in orthodontic anchorage, J Oral MaxillofacSurg. 2006;64:1209-13. 6. Herman R, Cope JB. Miniscrew-implants: IMTEC mini-ortho implants. SeminOrthod. 2005;11:32-9. Smile Dental Journal | Volume 7, Issue 3 - 2012 | 23 |