Extrusion of impacted mandibular second molar using removable appliance.

The purpose of this article is to review the principles of case management of impacted mandibular molars and to illustrate their potential to respond well to treatment. Although the scope of treatment may be influenced by the patient's age, past dental history, severity of impaction, dentoalveolar development, and root form, the case reports demonstrate the inherent potential for good treatment outcome even in the most unfavorable circumstances.

An impacted tooth is one that is embedded in the alveolus, so that its eruption is prevented or the tooth is locked in position by bone or the adjacent teeth.[1] Impaction of the lower second molar is a rare condition. Unilateral mandibular second molar impaction is more common than bilateral impaction. Incidence is more common in men than women, more frequent on the right side than left as mesially inclined.[2] The incidence of the second molar impaction revealed by panoramic radiograph studies has been reported as 0.03-0.04%[34] of all impacted teeth.

The case described below had a past dental history, which might contribute the etiology for the impaction of the permanent mandibular second molar the treatment was carried out with a removable appliance.

Case Report

A 21-year-old male patient with Class II subdivision presented with the chief complaint of missing teeth in his lower back tooth region. On clinical examination, impaction of 47 was noted with the distal cusps exposed among the alveolar mucosa in relation to 47. Patient presents a past dental history significant to the cause. He had a root canal treated 46 due to chronic pulpitis at the age of 10 years followed by a crown at the age of 16 years, which might be a significant cause to chief complaint of the patient.

Diagnosis and examination

On clinical examination, 47 was missing and impacted with distal cusps exposed in the oral cavity without any signs of pericoronitis in the alveolar mucosa of 47 region. On radiographic examination, orthopantomogram revealed vertical impaction of 47 without any resorption or pathology associated with the teeth and periodontium. It was clearly noted that the potential for eruption was disrupted by the porcelain fused metalic (PFM) crown luted on endodontically treated 46.

Precisely the distogingival margin of the PFM crown, which was over contoured in the distal aspect acted as an undercut preventing the eruption of 47 [Figure 1].

Figure 1

(a) Preoperative mandibular occlusal view showing impacted 47 with the visible distal cusps, (b) Right view, and (c) Preoperative orthopantomogram

Treatment plan

The treatment protocol has been planned and executed by Department of Orthodontics and Department of Periodontics. The first step involved in the management of impacted permanent second molar is periodontal surgery over the gingival mucosa in relation to the impacted teeth, which was required to gain access to the buccal surface of 47. The periodontal surgery was performed under local anesthesia with a carbon dioxide LASER. The LASER surgery was preferred since it had minimal bleeding thereby reducing bond failure on bonding. Picasso soft tissue diode laser (with 7 W, 810 nm) was used in the surgery. A bondable attachment (0.22 slot MBT premolar Bracket, Oramco) was placed in the exposed visible surface of impacted 47. Bondable bracket was preferred over buttons due to the advantage of wings and better bonding capacity. The attachment was exposed in the oral cavity during healing for connecting the appliance to the bonded attachment.

A removable appliance was constructed for extrusion of 47 since it has higher anchorage control over the fixed appliance and easy to design for this purpose.

Design of appliance

Removable appliance was the priority of choice due to the advantage of higher anchorage control and ease in design of the appliance.[2] Thus, a removable appliance was fabricated for mandibular arch with bilateral triangular clasp one in between 42, 43 and other in between 33, 34. Adams clasp one on the premolar on the fourth quadrant (45) and other on the molar in the third quadrant (36). A custom made retraction spring with helix made with 17 × 25 titanium molybdenum alloy (TMA) wire constructed with the acrylic material extending to the adams clasp of 46. The design of spring was simple. A horizontal arm made of TMA wire with a posterior helix on the distal end tied using a ligature wire to the bracket on the impacted 47[5] and an anterior helix with two turns present at the buccal region of 46, from the helix[6] of the wire extends into the acrylic along with crossover arm of adams clasp (on 45) to the lingual plate, finishing with a retention tag. The horizontal arm from the anterior helix to the posterior helix measures about 20 mm and the posterior helix with two full turns of 3 mm diameter is placed 1.5 cm above the bonded attachment thus, the force exerted when the posterior helix is tied to the attachment causes an extrusion force of 100 g/cm2 on the impacted 47 [Figures 2–4].

Figure 2

The extrusion appliance

Figure 4

(a) Preoperative, (b) 2 months after activation, (c) 4 months after activation, and (d) Postoperative

With the removable extrusion appliance engaged to the impacted teeth

Discussion

The construction and design of the appliance helped in achieving the treatment goals, which is extrusion of molar (47) and preserving the anchorage for its extrusion. The appliance's merits are simple design, easy to fabricate, cost-effective, and anchorage control.[7] Likewise, there are demerits but of lesser significance than of merits, which are patient cooperation and initial speech disturbances. Furthermore, the duration of this treatment was 7 months, which is considerably effective with monthly periodic visits and continuous force needed at the start of the treatment. The appliance scored higher in comparison with fixed appliance in the aspect of anchorage control as previously used removable appliance for maxillary canine impactions [Figure 5].

Figure 5

(a) Postoperative mandibular occlusal view showing erupted 47, (b) Right view, (c) Postoperative orthopantomogram showing a decrease in the distance between occlusal plane and 47 compared with preoperative

Result

The reduction of adversities such as de-arrangement of occlusion of the adjacent teeth, disturbance of bite is achieved by deriving anchorage from skeletal and soft tissue thereby avoiding impervious tooth movements. Maintenance by the patient was achieved as expected when compared with fixed appliance used for extrusion of impacted tooth at a significant acceptable duration. Further use of removable appliance for management of impacted teeth should be encouraged as the merits derived from the achieved in this treatment.