15 August 2023

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Techniques in alignment of impacted maxillary central incisors

Davide Elsido

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Central incisors rarely become impacted, with an incidence of 0.1–0.5%. The most common causes of central incisor impaction include obstacles in the eruption path, trauma to the deciduous dentition leading to developmental changes of the permanent tooth and a deviated eruption path. 

Typically, the maxillary permanent central incisor begins to erupt around six years of age. When physiologic eruption does not occur, the patient should be referred for orthodontic evaluation. 

Under normal circumstances, the maxillary lateral incisors are the last of the incisors to erupt, appearing approximately one year after the eruption of the adjacent central incisors to complete the anterior dentition. Further changes in dentition do not occur until approximately 10 years of age. 

As such, there is a two-year period of relative stability known as the mixed dentition stage. When both lateral incisors have erupted and one or both central incisors are missing, further investigation is warranted. If an impacted tooth is suspected, X-ray imaging is essential for diagnosis (orthopantomogram, OPG), which usually reveals the cause. To obtain a precise diagnosis and to visualize the position and relationship to adjacent anatomical structures, a cone-beam computed tomography (CBCT) is usually indicated. 

The choice of orthodontic approach for alignment of the impacted tooth into the dental arch should be carefully considered and guided by clinical and radiological examinations. 

Treatment of an impacted maxillary incisor involves orthodontic space preparation, followed by surgical elimination of any obstacles. In many cases, this may be sufficient to encourage the autonomous eruption of the affected tooth, with periodontal and esthetic parameters approximating those observed with physiologic eruption. 

However, when the impacted tooth does not spontaneously erupt when the obstacle is removed and sufficient space is available, enhancement of the natural process is required. This entails surgical exposure of the crown of the impacted tooth, bonding of an attachment, and the application of extrusive force between the tooth and an existing labial archwire. 

Choosing the appropriate treatment approach is critical, with many demands being placed on the orthodontist with respect to esthetic outcome, future dental health, and long-term prognosis.

The tooth will almost always erupt, but the outcome is often negatively affected by an insufficient width of attached gingiva and an elongated clinical crown. 

To overcome potential collateral damage and improve overall prognosis, this study presented an improved ortho-surgical approach that directs the vertically advancing tooth in a lingual direction, as opposed to the standardly used labial direction. The directional force is applied from a simple spring-drawn or elastic-drawn device which, following a closed exposure procedure, guides the tooth to erupt through the attached gingiva on the crest of the alveolar ridge. This procedure best approximates physiologic spontaneous tooth eruption and as such provides an ideal foundation for long-term esthetics and functionality of the tooth.

The aim of this study published on June 26 in Progress in Orthodontics is to compare the outcomes of patients treated with this approach and those treated with spontaneous eruption of impacted teeth following a space opening procedure.

In this retrospective study, thirty-one consecutive patients (13 boys, 18 girls; average age 9.5 ± 2.3 years) with a total of 34 impacted permanent upper central incisors were included in the study. Patients were divided into two groups according to method of treatment. 

Group A comprised patients in whom spontaneous eruption occurred after space opening (n = 12), and Group B comprised patients in whom teeth showed no eruption and required treatment with a modified closed eruption method with palatally oriented traction (n = 19). 

Treatment time and esthetic outcomes were assessed and compared between groups.

Results 

The mean treatment time was 22.0 ± 6.7 months, and all teeth were successfully aligned. No statistically significant difference in average treatment time was found between groups in baseline characteristics (p > 0.05). The amount of attached gingiva was significantly smaller when compared to contralateral reference teeth in the closed eruption group (Group B; p = 0.03). However, no difference in amount of attached gingiva was found between both groups (p = 0.26). Additionally, no difference in the clinical crown length was found between groups (p = 0.27).

Conclusion

The closed eruption method with palatal traction directed at the peak of the alveolar crest provided results comparable to the physiologic tooth eruption.

Marek, I., Janková, A., Starosta, M. et al. "Comparison of spontaneous eruption and modified closed eruption technique with palatal traction in alignment of impacted maxillary central incisor teeth." Prog Orthod. 24, 17 (2023). https://doi.org/10.1186/s40510-023-00470-7