Combined surgical and orthodontic treatment of impacted second lower premolar – Case report

Summary Impacted tooth is a tooth that has failed to reach occlusal plane, with 2/3 of completed root growth. There are various reasons for teeth impaction, however, lack of space for its emergence is considered to be the main reason. The most commonly impacted teeth are lower wisdom teeth, then upper wisdom teeth, upper canines, and less frequently lower premolars. There are only few studies that have addressed the issue of impacted lower premolars, their etiology, prevalence and treatment. The patient (22 years old) visited orthodontst for the lower jaw aesthetic teeth corrections, due to crowding. Ortopantomography analysis revealed impacted lower right second premolar that caused resorption of mesial root of the first molar. The treatment plan included tooth #46 extraction and placing orthodontic brackets on the impacted second premolar. The next step was extrusion of the tooth #45, its introduction to occlusal plane and orthodontic treatment resumption. Orthodontic treatment of impacted teeth with fixed orthodontic appliance provides excellent therapeutic results. The treatment success depends primarily on adequate planning, cooperation and joint work of oral surgery and orthodontic specialists.


INTRODUCTION
Impacted lower premolars are not so rare in everyday dental practice. Lower premolars are most frequently impacted teeth, after lower and upper third molars and upper canines [1]. Mandibular premolars erupt after first lower molars and canines, so the lack of space for the eruption of both premolars may lead to impaction of one of them, usually the second premolars [2]. Some of the reasons for their impaction are: lack of space, ectopic position of the tooth bud, presence of obstacles (primary tooth, tumor, scar tissue) on the way of eruption, presence of supernumerary teeth or odontomas. Some of the systemic and genetic diseases such as ccd dysplasia, osteoporosis, Down syndrome, hypothyroidism and hypopituitarism may affect premolars eruption as well [3][4][5].
Treatment of impacted mandibular premolars depends on tooth position, depth of impaction, relationship with surrounding teeth, as well as planned orthodontic treatment. Treatment includes teamwork: orthodontist who makes treatment plan and oral surgeon who performs surgery to allow access to the impacted tooth. The treatment procedure involves surgical release of the impacted premolar`s crown, bonding orthodontic bracket and further fixed orthodontic treatment. One of the conditions for successful therapy is that the angle of the impacted premolars does not exceed 45° [6].
This case report presents surgical release of impacted lower right second premolar with subsequent orthodontic treatment.

CASE REPORT
The patient (22 years old) presented for an orthodontic examination in order to address the problem of irregular position of the tooth (lack of space) in the lower jaw ( Figure 1). After ortopantomography analysis it was observed that lower right second premolar is impacted with suspected resrption of mesial roots of the the first molar. Also, the first lower left premolar was noticed to be missing as well as unerupted wisdom tooth in the fourth quadrant ( Figure 2). The patient was healthy and did not have any previous tooth extraction or orthodontic intervention in dental history. Also, he did not report pain or discomfort in the orofacial region.
Orthodontist sent patient to oral surgeon for consultation. Mutual treatment plan was done which included combined surgical-orthodontic treatment. It included extraction of the first lower right molar (#46) and then orthodontic extrusion of the lower right second premolar (#45). First molar was suggested to extraction primarily due to the resorption of mesial root but also making enough room for premolar.
Oral surgery was performed under local anesthesia after the placement of fixed orthodontic appliance. A corner gingival flap of full thickness was carefully lifted between canine and second molar, with taking care of the mental nerve. The tooth #46 was extracted carefully with forceps when midroot resorption of the mesial root caused by emergence of the impacted premolar #45 was observed. The remaining apical part of the root was extracted as well ( Figure 3). The entire crown of the impacted second premolar was exposed ( Figure 4). The bone around the crown of #45 was removed with carbide burs under constant cooling with sterile saline. This allowed orthodontic bracket placement on the tooth ( Figure 5). Individual su-tures were placed for 7 days. The patient was prescribed antibiotics (Dovicin 100 mg, 7 days), Chymoral Forte (5 days) for quicker resorption of edema and hematoma and pain killers as needed.
Further orthodontic treatment was focused on the extrusion of the impacted premolar over the next 6 months, its positioning in the dental arch and reaching the occlusal plane ( Figure 6). At the same time the lack of space was corrected as well. Orthodontic therapy will be fully completed after wisdom tooth emergence in the fourth quadrant that will fully stabilize occlusion in lateral region.

DISCUSSION
Literature does not provide sufficient data related to the impacted lower premolars, regardless the fact that frequency of these tooth impaction is quite high [7]. The treatment of these teeth is multidisciplinary and includes cooperation of orthodontics with oral and maxillofacial surgeons, pediatric dentists and sometimes endodontists [8]. Treatment plan depends on several factors, primarily on the ammount of space available to initiate the emergance of impacted tooth, depth of impaction, degree of root formation, need for first molar extraction, duration of the therapy and presence of keratinized gingiva. In addition, treatment plan is significantly influenced by the patient`s state of general health, other teeth and oral hygiene, as well as function and occlusion [9,10]. Andreasen recommended surgical exposure of impacted premolar to be limited to cases where the angulation of the tooth is not greater than 45° in both jaws. However, in practice, we can find cases of surgical and orthodontic treatment of horizontally impacted mandibular premolars that were successfully placed in their dental line position [8].
In cases where OPT and clinical examination show lack of space for impacted mandibular premolars, regular checkups are needed, extraction of the primary teeth as well as monitoring of the permanent premolars position. If necessary, surgical release of the tooth crown, with or without orthodontic traction or repositioning (autotransplantation) may be performed. However, if impossible to align impacted mandibular premolar in dental arch then surgical removal of the tooth should be done [11].
To align impacted mandibular premolar, orthodontic treatment should be divided into the three phases. The first phase starts 2 to 5 months after surgical exposure of a tooth. The second stage starts when tooth is tracted to its position in dental arch and lasts 12 to 18 months. The third stage is the end of orthodontic treatment when the tooth is in its place in the arch, having in mind that additional 10 to 18 months are required for completion of orthodontic treatment [12].
One of the possible complications of impacted mandibular premolars is the occurrence of developmental cyst of odontogenic origin [3]. These cysts are common in impacted, retained or developing teeth. As they give none or minor symptomatology they are usually diagnosed accidentally during routine examination or radiography. These cystic lesions often reach large dimensions that may lead to mobility and migration of surrounding teeth or resorption of their roots. Therefore, complete removal of cystic lesions (cystectomy) with impacted tooth extraction are necessary [13]. Sometimes, in order to keep the tooth, marsupialization, that has aim to decompress and fenestrate cystic wall is performed with release of impacted tooth and continuation of the orthodontic treatment [14].
There is an increasing number of young patients with impacted permanent teeth problem (not just wisdom teeth) and successful correction of existing orthodontic anomaly is often complex and lengthy process. Careful and thorough treatment planning, as well as good cooperation of oral surgeon and orthodontists, is crucial to achieving treatment success. Teamwork, regular checkups and good patient cooperation eventually lead to excellent results.