Lama Hussam JarrahBDS, MSc, JBO
This case of a 10 year old boy presents a combination of incisor impaction and canine transposition. Deciduous teeth were retained. The impaction was probably secondary to trauma received at 18 month of age. An interdisciplinary approach to treatment with different mechanical strategies led to the achievement of the desired esthetic, functional, and occlusal treatment goals. The term Expired Primary Teeth is used to emphasizes the harmful existence of the retained deciduous teeth.
Variation in the time of shedding of deciduous teeth and emergence of their permanent successors is common, but significant deviation from the established norms is an alert for a potential impaction. As early as 1959, Newcomb 1 reported that experience had taught him “. . . with few exceptions. . . potential impaction of permanent teeth is seen in patients exhibiting moderate to severe retardation of dental maturation . . . a slow rate of permanent teeth formation.”
Reviewing the literature many causes of anterior permanent teeth impaction are listed, one of which is trauma to the anterior deciduous teeth .2, 3, 4 The prevalence of eruption disturbances in the permanent anterior teeth following trauma to their predecessors is 17.97%. 5 Treatment and prognosis of impacted anterior teeth is influenced by various factors. Treatment options may include passive observation, exposure with traction, or extraction of the tooth.
This case of a 10 year old boy discusses the treatment and handling of an infrequent type of impaction. Upper left central was impacted, and both of the upper left lateral incisor and canine were ectopically erupting. The canine demonstrated an incomplete transposition with the lateral. Impaction was probably secondary to a previous trauma of the deciduous teeth.
A healthy 10 year old boy presented with retained deciduous teeth (a,b) in the upper left side (Fig 1). Upper left deciduous central incisor is discolored and non vital. Occlusion exhibit a Class I molar relationship, and lower anterior crowding (Fig 2, 3).
Clinical examination revealed an alteration of normal dental development. Dental history revealed that upper deciduous teeth were traumatized at the age of 18 months. Trauma may have caused displacement of the tooth bud of upper left central incisor. To assess the situation a panoramic radiograph was taken (Fig 4).The radiograph showed the impaction of upper left central, ectopic eruption of lateral incisor and incomplete transposition of the canine.
Treatment Plan and Progress
Treatment commenced by extracting the expired deciduous teeth; (upper left deciduous central, lateral, and canine). A modified spoon denture was fabricated. It helped in keeping the space, preventing midline shift, facilitating proper articulation, and gave an acceptable esthetic look for the patient. (Fig 5, 6).
Four months later a new panoramic radiographic x-ray was taken (Fig 7). The overall scene did not change. 3D dental CT image was taken to identify any obstruction that would prevent eruption, verify the 3- dimensional relation between the roots of the teeth in question, and to plan the force direction during orthodontic traction. Supernumerary tooth were not observed in the 3D X-ray. The roots of upper left lateral and canine were separated by around 2mm of alveolar bone (Fig 8).
Active treatment started. Fixed appliance (0.022 MBT prescription) was bonded. An upper 0.016 stainless steel wire with three loops on the left side was attached to the fixed appliance. Closed surgical technique was performed under GA. Upper left central, lateral, and canine were exposed and attachment placed (Fig 9, 10). Selective traction commenced after two weeks. The first priority was to move the lateral away from the path of the central (Fig 11).
Traction was performed by light ligature wire keeping forces to the minimum. Downward and distal traction was applied to the upper left lateral and canine, no traction was applied to the central. Three months after active treatment the lateral began to appear in the oral cavity. At this stage active traction commenced to the upper left central and canine, while still applying traction to distalize the upper left lateral. The central appeared in the oral cavity 8 months later (Fig 12), followed by the canine (Fig 13).
During the aligning and leveling a regular -7 torque bracket was placed on the canine, and +17 torque on the upper lateral incisor. After achieving alignment and leveling. The roots of the canine and lateral are now not in the way of each other. The lateral needed a labial root torque, while the canine needed a palatal root torque. The bracket of upper left lateral was rotated 180° to change the torque from positive to negative this assisted in labial root torque at the rectangular wire stage. A positive torque bracket +7 was placed on the upper left canine to move the canine root to the middle of the arch.6T
The impacted teeth were positioned into proper alignment, rendering a complete anterior dentition and a nice smile. Treatment time was 26 months (Fig 14, 15). Upper left lateral incisor root needed more labial root torque, but due to the amount of movement already made and length of treatment, it was decided to accept its position (Fig 16).
This case presents an infrequent type of impaction. Upper left central was impacted, upper left lateral incisor was ectopically erupting, and the canine was demonstrating an incomplete transposition with the lateral. The impaction was probably secondary to a trauma received at 18 month of age.
The general guideline is that contralateral teeth should erupt within 6 months of one another. When there is significant delay in the eruption of a contralateral tooth for more than 6 month, the presence of a causative factor should be suspected. 7, 8 Expired primary teeth (retained) is an alert of a potential impaction. The term Expired Primary Teeth is used to emphasize the harmful existence of retained deciduous teeth. It implies that deciduous teeth have a time span beyond which they expire. Diagnostic tests should be performed when eruption is delayed for more than 6 months .9 Earlier treatment (before 8 years of age) usually has better results.10
Treatment commenced with extracting the expired deciduous teeth; (upper left deciduous central, lateral, and canine). Hoping to encourage the natural eruption process. 11 A modified spoon denture was placed to keep the space, prevent midline shifting, help in proper articulation and give an acceptable esthetic look to the patient.
3D dental CT images were taken to identify any obstruction preventing the eruption of the central incisor, verify the 3- dimensional relation between the roots of the teeth in question, and plan the force direction during orthodontic traction. The highly detailed information gained outweighs the extra radiation dose, and cost. Confluent images of the hard palate and zygomatic bone in conventional radiographs, prevents obtaining a clear picture of impacted teeth in the maxilla. Computerized tomography is the method of choice for accurately defining the position of an unerupted tooth and identifying any root resorption of adjacent teeth.12
Closed eruption technique was used in this case to induce normal eruption of teeth through keratinized gingivae. The surgical technique used can influence the outcome of the gingival contour. Many studies revealed superior periodontal index values and esthetic results with the closed eruption technique. Closed eruption technique help preserve the width of the keratinized gingival margins, prevent vertical irregularities of the attached gingival margins, and reduce alveolar bone loss. 13, 14Evaluation of the treatment outcome showed an acceptable periodontal gingival contour with adequate width of keratinized attached gingival tissue but with a reddish collar of attached gingivae over the upper left central incisor.
Light forces were used to move the teeth towards the dental arch. Using light forces prevent bracket debonding, tooth ankylosis, gingival loss, or cant of the maxillary occlusal plane .8,15 Moreover the use of light forces decrease the possibility of root resorption. 16
Upper left lateral needed labial root torque, and the upper left canine needed a palatal root torque. The torque was not applied until the roots of these teeth were not in the way of each other. The bracket of upper left lateral was rotated 180° to change the torque from positive to negative this assisted in labial root torque when rectangular wire were used. A positive torque bracket +7 was placed on the upper left canine to move the canine root to the middle of the arch.6 Torque application continued for 3months. The left lateral incisor could take more labial root torque. However, the prolonged application of torque and use of rectangular archwires can be a possible cause of root resorption. 16
Expired deciduous teeth in the oral cavity must alert the clinician of a potential impaction. Successful management of anterior impacted maxillary teeth can be challenging in a clinical practice. Early diagnosis, appropriate surgical technique, and light orthodontic forces are pre-requite for a satisfactory treatment outcome.
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