Australian Dental Journal

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1 Australian Dental Journal The official journal of the Australian Dental Association CASE REPORT Australian Dental Journal 2010; 55: doi: /j x Intrusion of an overerupted mandibular molar using mini-screws and mini-implants: a case report A Arslan,* D Nalbantgil Ozdemir, H Gursoy-Mert,à O Malkondu, K Sencift* *Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Yeditepe University, Goztepe, Istanbul, Turkey. Department of Orthodontics, Faculty of Dentistry, Yeditepe University, Goztepe, Istanbul, Turkey. àdepartment of Periodontology, Faculty of Dentistry, Yeditepe University, Goztepe, Istanbul, Turkey. Department of Prosthodontics, Faculty of Dentistry, Yeditepe University, Goztepe, Istanbul, Turkey. ABSTRACT Overeruption of mandibular molars due to the loss of antagonist teeth causes occlusal functional disturbances. To restore proper occlusion, intrusion of the overerupted molars becomes essential before multidisciplinary reconstructive dental approaches can be initiated. Treatment protocols involving prosthodontic reduction, surgical impaction, and conventional orthodontic intrusion have been introduced. Orthodontic intrusion seems to be a favourable procedure which requires calibrated anchorage support. This case illustrates the management of a complex dental and functional problem with an interdisciplinary approach through the use of orthodontic, periodontal, restorative and implant therapy. In order to intrude the overerupted molar, a partial orthodontic appliance was used in conjunction with mini-implants and mini-screws. The results showed that the biological responses of the teeth and the surrounding bony structures to the intrusion appeared normal and acceptable. Periodontal health and vitality of the teeth were maintained throughout the treatment and even after one-year follow-up. Keywords: Overeruption, molar, mini-screw, mini-implant. (Accepted for publication 17 January 2010.) INTRODUCTION Overeruption of lower molars due to the loss of antagonists may cause occlusal interference problems. To reconstruct proper occlusion of the posterior dentition and maintain periodontal health, an interdisciplinary and comprehensive approach is necessary. Correction of the overerupted molar is essential and should be the first step before other procedures can commence. Procedures involving orthodontic intrusion, prosthodontic reduction and surgical impaction have been presented. 1 4 Conventional orthodontic methods which require complex appliance or brackets applied to many teeth are used to reinforce the anchorage. But the treatment result is not always effective because of side effects, such as extrusion and tipping of the anchorage teeth. Burstone and Koenig 5 state that an intrusive force on the molar can only occur when an extrusive force is placed on the premolars. Extrusion of these adjacent teeth would decrease the overbite which may cause a negative effect on the occlusion and profile of the patient by increasing the lower facial height. When these side effects are considered, skeletal anchorage seems to be a much more comfortable and reliable method both for the patient and the clinician. This case illustrates the solution of a complex dental and functional problem with an interdisciplinary approach through the use of orthodontic, periodontal, restorative and implant therapy. An adequate space is prepared for the missing upper molars by intruding the overerupted lower molar using mini-screws and mini-implants for skeletal anchorage. CASE DESCRIPTION AND RESULTS A 23-year-old female was referred to our clinic with an extruded left mandibular second molar. Intraoral dental examination, together with the assessment of the panoramic radiograph, revealed that the left maxillary first and second molars had been extracted and a bridge was present which included upper first and second premolars. It was observed that there was not enough space for a proper prosthesis in the upper left ª 2010 Australian Dental Association 457

2 A Arslan et al. Fig 1. Intraoral view of the overerupted left mandibular second molar. Fig 3. Intraoral view of the overtrimmed occlusal surfaces of the left mandibular second premolar and first molar. molar region because of the overerupted mandibular second molar (Figs 1 and 2). Figure 3 shows overtrimmed occlusal surfaces of the mandibular second premolar and first molar which was undertaken in order to make space for the upper antagonist bridge. The patient had a balanced facial profile with Class III and Class II canine occlusion left and right side, respectively. Although a comprehensive treatment course of care was offered to the patient, she declined to have any full-mouth orthodontic intervention. An alternate plan accepted by the patient included the intrusion of the overerupted mandibular second molar together with the levelling of the lower left segment in order to build a new bridge that utilized upper first and second premolars as abutments and a cantilever pontic in the first molar site. It was decided to provide the anchorage by mini-implants and mini-screws with partial fixed edgewise appliances. Under local anaesthesia, two mini-implants (2 mm diameter, 11 mm length; Modus Ò IMF, Medartis, Basel, Switzerland) were placed in the vestibular bone near the apical region away from the apex of the mandibular extruded second molar, one between the first molar and second molar and the other distal to the second molar. In order to prevent buccal flaring of the second molar, two miniscrews (1.2 mm diameter, 10 mm length; Abso Anchor Dentos Ò, Daegu City, South Korea) were placed subsequently to the lingual side of the overerupted molar, between mandibular first molar and second molar, one above the other (Fig 4). Before the placement of the mini-screws lingually, a flap was reflected to determine the location of the lingual nerve and miniscrews were placed away from the lingual nerve. The infected mandibular third molar was also extracted during the same operation. Antibiotic (Amoxicillin + Clavulonic acid, Augmentin Ò, GlaxoSmithKline, Turkey; 1 g orally, twice daily), analgesic (Naproxen sodium, Apranax Fort Ò, Abdi _ Ibrahim, Turkey; 550 mg, orally, twice daily) and mouthrinse (Chlorhexidine Digluconate, Klorhex Ò, Drogsan, Turkey; orally, three times a day) were prescribed postoperatively. Other screws or implants could not be applied to the distolingual side of the overerupted lower second molar due to the anatomic considerations. At the Fig 2. Radiologic view of the patient showing overerupted left mandibular second molar. Fig 4. Postoperative radiologic view of the patient. 458 ª 2010 Australian Dental Association

3 Intrusion of an overerupted mandibular molar beginning of the treatment, the upper screw was initially to be used to apply the retraction force to intrude the overerupted molar and the other was kept as an extra anchorage unit. After some intrusion was achieved, the lower screw was then used in order to have enough activation distance. Intrusion was done with elastics applied to screws located buccally and lingually. In order to achieve a better intrusion force, the anchorage unit must be located as far as possible from the occlusal surface, which is a clinical determining factor for the activation distance. Activation distance is the necessary distance between the occlusal surface and the anchorage unit. The amount of intrusion increases proportionally with the activation force applied. After some intrusion is obtained, due to the insufficient activation distance between the upper screw and occlusal surface, the second lower screw was preferred to continue to have the proper force. A medium intrusive force ( mg) was applied both with the coil spring between the buccal implant and attachment of the molar band, and elastic thread between the lingual mini-screw and the cleat of the molar band (Fig 5). After the intrusion process, which was completed in five months, levelling of the adjacent teeth was commenced. Partial fixed edgewise appliances were applied to the lower first and second premolars and first molar. Levelling was performed by utilizing Ni-Ti archwires in regular sequence. During the intrusion period, mild oedema and inflammation of the gingival tissue was observed in the vestibular mucosa. In order to manage gingival problems, oral hygiene was checked every two weeks at the beginning of the intrusion process. It was ascertained that oral hygiene was satisfactory. The patient was reviewed on a monthly basis and advised to brush around the screws and to rinse with an antibacterial mouthwash (Listerine Ò, Johnson and Johnson, Turkey). Fig 6. View of partial fixed appliance on the lower first and second premolars and first molar to correct the position of the lower second molar. Fig 7. Radiologic view of the intruded mandibular left second molar and the broken lingual mini-screw after one and a half year follow-up. Fig 5. Intraoral view of mini-screws and mini-implants attached to the lower second molar by coil spring and elastic thread. Fig 8. Intraoral view of the intruded left mandibular second molar. ª 2010 Australian Dental Association 459

4 A Arslan et al. Three months later, sufficient correction was attained (Fig 6). Periodontal crown lengthening was performed on the maxillary left premolars to facilitate an improved retention of the new bridge. Since the occlusion was restored immediately after levelling with a bridge on the upper posterior region, no retainer was required to maintain the overerupted mandibular second molar. All the mini-screws and mini-implants, except one, were removed under local anaesthesia. The upper mini-screw placed lingually was broken during removal and it was decided to leave it in its place to prevent bone loss while trying to unscrew it. In the first year and a half of follow-up, no root resorption of the intruded molar and no complication around the remained screw was observed (Figs 7 and 8). It was observed that the intrusion process was stable. During this interdisciplinary process, the vitality of the teeth was preserved. DISCUSSION Treatment protocols to manage overerupted teeth are prosthodontic reduction, surgical impaction and conventional orthodontic intrusion. 1 4 However, prosthodontic preparation of these teeth requires endodontic intervention and crown restoration at the expense of tooth vitality, whereas surgical impaction involves an aggressive segmental operation. Hence, orthodontic intrusion seems to be a favourable procedure which requires calibrated anchorage support from intraoral multi-unit teeth. In this case report, in order to intrude the overerupted molars, a simple and partial orthodontic appliance was used in conjunction with miniimplants. The results show that the biological responses of the teeth and the surrounding bony structures to the intrusion appear normal and acceptable. Periodontal health and vitality of the teeth were maintained throughout the treatment and even after one-year follow-up. Conventional orthodontic intrusion is acceptable but requires a longer treatment time. Individually designed intrusive mechanics require the splinting of either as many teeth as possible, or even a full arch as one solid anchor unit to avoid unwanted movement. 6 Furthermore, to reinforce the anchorage, the patient may be asked to wear an extraoral appliance. The purpose of using implants as skeletal anchorage is to totally eliminate the need for patient compliance and the need to wear extraoral auxiliaries, while overcoming the difficulty resulting from a shortage of anchor teeth. The number of teeth splinted can be reduced, and the side effects to the anchoring tooth unit can be minimized. In the present case, the patient was reluctant to have a full arch orthodontic treatment. Therefore, only three teeth in the left lower dental arch, in addition to implants to intrude the second mandibular molar, tooth were used. Although the insertion of mini-implants requires flap surgery and proper instrumentation, the patient did not report experiencing much discomfort about the surgery. The only complaint was a disturbance in tongue movements due to the location of the lingual screw but the patient tolerated it well. The orientation of the intrusive force from the implants to the molar attachments determines the direction of the tooth movements. Thus, the placement of the mini-implants becomes critical where the line of intrusive action needs to pass through the centre of resistance. Anchored implants have been reported to be biocompatible. 7,8 Therefore, we consider that titanium screws, even left in their place, will not cause any complication. In this report, we have demonstrated a simplified version of combining mini-implants with a partial fixed edgewise appliance to intrude the mandibular second molar. Most importantly, the molar responded well to the intrusive forces throughout treatment, no root resorption was detected during follow-up and the vitality of the teeth was sustained even after one and a half year follow-up. The coordination of different specialties allowed us to gain optimal results in a shorter treatment time. CONCLUSIONS The case presented in this article demonstrates the intrusion of an overerupted mandibular second molar using mini-screws and mini-implants for skeletal anchorage. The favourable result obtained shows that the intrusion procedure is an acceptable treatment option for extruded molars that can be preferred instead of prosthodontic reduction or the extraction of the extruded tooth. DISCLOSURE All authors have no financial interest in any of the products or companies mentioned in this article. REFERENCES 1. White R, Terry B. Segmental jaw surgery. In: Proffit WR, White RP, eds. Surgical Orthodontic Treatment. St. Louis: Mosby, 1991: Smith B. Occlusal considerations. London: Martin Dunitz, 1987: Rosen P, Forman D. The role of orthognathic surgery in the treatment of severe dentoalveolar extrusion. J Am Dent Assoc 1999;130: Daly PF, Pitsillis A, Nicolopoulos C. Occlusal reconstruction of a collapsed bite by orthodontic treatment, pre-prosthetic surgery and implant supported prostheses. A case report. SADJ 2001;56: ª 2010 Australian Dental Association

5 Intrusion of an overerupted mandibular molar 5. Burstone CJ, Koenig HA. Force systems from an ideal arch. Am J Orthod 1974;65: Melsen B. Management of severely compromised orthodontic patients. In: Nada R, ed. Biomechanics in clinical orthodontics. Philadelphia: WB Saunders, 1997: Yao CC, Wu CB, Wu HY, Kok SH, Chang HF, Chen YJ. Intrusion of the overerupted upper left first and second molars by miniimplants with partial-fixed orthodontic appliances: a case report. Angle Orthod 2004;74: Ohmae M, Saito S, Morohashi T, et al. A clinical and histological evaluation of titanium mini-implants as anchors for orthodontic intrusion in the beagle dog. Am J Orthod Dentofacial Orthop 2001;119: Address for correspondence: Dr Hare Gursoy-Mert Assistant Professor Department of Periodontology Faculty of Dentistry Yeditepe University Bagdat Cad No Goztepe Istanbul Turkey haregursoy@hotmail.com ª 2010 Australian Dental Association 461