Prevalence, characteristic features, and complications associated with the occurrence of unerupted permanent incisors

Abstract

This study examined the prevalence, characteristic features, and complications associated with the occurrence of unerupted permanent incisors among children and adolescents attending a university dental teaching hospital. A retrospective review was performed of the clinical records of children and adolescents who attended the Prince Philip Dental Hospital, Hong Kong between 2005 and 2014. All patients who had at least one unerupted permanent incisor tooth were included. A total of 266 subjects with 320 unerupted permanent incisors were identified. The prevalence of unerupted permanent incisors among children and adolescents was 2.0%. Permanent maxillary central incisors (70.6%) were the most commonly affected teeth. The most common cause for unerupted incisors were dilacerations (n = 83, 36.7%) for maxillary central incisors; developmental dental anomalies (n = 22; 30.6%) together with unfavorable root development (n = 22; 30.6%) for maxillary laterals incisors; and abnormal tooth/tissue ratio (n = 11, 50.0%) for mandibular incisors. A majority of unerupted incisors presented with complications the most common being ectopic/displacement/rotation of the unerupted incisors (46.6%), loss of space (36.9%) and midline shift (27.5%). In conclusion, the causes were distinct for different manifestations of unerupted permanent incisors. As the majority of unerupted incisors presented with complications, a systematic and organized method of history taking as well as clinical and radiographic examinations is mandatory in the diagnosis of unerupted permanent incisors.

Fig 1. Panoramic radiograph of a 14-year-old girl (with no history of dental trauma) presented with root dilaceration of #9, unerupted #8 with enlarged follicle, unerupted #7 and #10 with delayed root development; as well as an impacted #22.

Fig 2

a. Upper anterior occlusal view of a 12-year-old girl who presented with a crown and root dilacerations of #8 as well as positive history of traumatic injury to the primary incisor when she was 4-year-old. b. Intra-operative photograph of the same subject which shows the orientation of the dilacerated crown. c. Postoperative photograph of the same subject with the extracted #8 and its associated tooth follicle.

Fig 3

a. Periapical radiograph of an 8-year-old boy who presented with an unerupted #8 due to the inverted mesiodens between #8 and #9. b. Frontal view of the same subject with erupting #7 and #8 after one month of surgical removal of the inverted mesiodens between #8 and #9. c. Occlusal view of the same subject showing talon’s cusps and dens invaginatus on palatal surface of erupted #10 (black arrow) after six months of surgical removal of the inverted mesiodens between #8 and #9.

Fig 4. A 9 years old male subject who initially presented on 15^th January 2011, with malformed and delayed root development on #10 (white arrow).

#11 (black arrow) had erupted in advance as compared to #10 on a review dated on 1^st August 2012. #10 had finally erupted clinically on the subsequent review dated on 21^st November 2012 (after 22 months of observation).

Fig 5. Panoramic radiograph of an 8-year-old boy showing the complications associated with the occurrence of an unerupted and ectopic #26.

Fig 6. Panoramic radiograph of an 8-year-old boy showing the unerupted #10 with delayed root development (white arrow), which also acted as an obstruction to the eruption of #9 (black arrow) and #11 (dotted arrow).