Assessments of Prevalence of Ponticulus Posticus, Atlas Posterior Arch Deficiency, Sella Turcica Bridging, Maxillary Canine Impaction, and Associations Among Them in 500 CBCTs of Italian Orthodontic Patients

Background: The ponticulus posticus (PP) is an important anomaly of the atlas (C1 vertebra) with a complete or partial bone bridge that transforms the groove of the vertebral artery (VA) into a canal (arcuate foramen). The aim was to retrospectively determine prevalence of PP evaluating morphological features and the possible association with other dentoskeletal anomalies in the midface and neck area such as maxillary canine impaction (MCI), atlas posterior arch deficiency (APAD), and sella turcica bridging (SB).Methods: This study was conducted in the Department of Medical, Oral and Biotechnological Sciences of the University “G. D'Annunzio” in Chieti. The detection of PP was performed on 500 patients with cone beam CT (CBCT) images (6 to 87 years).Results: Analysis revealed the presence of uni- and bi-lateral PP in 110 patients (22%): 24 (4.8%) patients with bilateral complete PP, 12 (2.4%) patients with complete PP on the left, 6 (1.2%) patients with complete PP on the right, 8 (1.6%) patients with complete PP on the right and partial PP on the left, 6 (1.2%) patients with complete PP on the left and partial PP on the right, 26 (5.2%) patients with partial bilateral PP, 18 (3.6%) patients with partial left PP, and 10 (2%) patients with partial PP on the right. The Chi-squared statistic confirmed that there are significant associations between MCI and PP (p = 0.020) and between SB and MCI (p <0.00001). No correlation between chronological age and presence of the PP (p = 0.982), between chronological age and morphotypes of the PP (p = 0.779), between APAD and the PP (p = 0.0757), between SB and the PP (p = 0.111), and between APAD and MCI (p = 0.222) were found.Conclusion: This observational study showed how bilateral partial variant and bilateral complete variant are the most represented morphotypes in all the age groups. The prevalence of MCI is positively associated with PP and with SB.

Evaluación del ponticulus posticus según la relación esquelética en radiografías laterales estrictas

Objetivo: Evaluar el ponticulus posticus según la relación esquelética encontrada en radiografías laterales estrictas en la Centro Dental Docente de la Universidad Peruana Cayetano Heredia durante el período 2015-2017, utilizando la clasificación de acuerdo al grado de mineralización descrita por Selby y la clasificación de la relación esquelética de Steiner. Material y Métodos: Se realizó en radiografías laterales estrictas digitales usando una pantalla de 20 pulgadas utilizando el programa SIDEXIS XG, observando el grado de mineralización del ponticulus posticus: sin evidencia de la espícula ósea sobre la arteria vertebral = puente ausente, cuando se notaba o evidenciaba la formación de la espícula y/o calcificación en medio del puente o en forma incompleta = puente parcial, cuando el arco óseo estaba evidente terminado visualizándose = puente completo y la clasificación de la relación esquelética midiendo el ángulo ANB: Clase I = 0-4°; Clase II = >4° y Clase III = <0°: el análisis estadístico se hizo con el programa SPSS V.22.0 para Windows mediante las pruebas de Chi2. Resultados: De las 925 radiografías laterales estrictas digitales evaluadas se encontró que 283 radiografías presentaron ponticulus posticus y la mayor frecuencia se encontró en el tipo ausente (69,4%), el tipo parcial (17,1%) y el tipo completa (13.5%). El ponticulus posticus se presentó en 25.1% del sexo femenino y en 38.4% en el sexo masculino. La relación esquelética asociada al ponticulus posticus se presentó en la Clase II (19.1%), Clase I (10,4%) y Clase III (1.1%), Conclusiones: El ponticulus posticus es una variante anatómica que se presenta en el 30,6% de los casos. No se encontró diferencia estadísticamente significativa entre la presencia de ponticulus posticus y la relación esquelética o sexo.

C1-2 Pedicle Screw Fixation for Ponticulus Posticus and Duplication of Vertebral Artery: 2-Dimensional Operative Video

We previously introduced C1 pedicle screw placement to treat C1-2 pathology in a patient with normal vertebral artery anatomy.1 However, we should prepare to meet various anatomic variations. Ponticulus posticus is a bony prominence arising from the posterior arch or the superior articulating process of the atlas that completely or partially encircles the vertebral artery.2 We herein report a 79-yr-old female who presented with myelopathy and was diagnosed with compressive myelopathy at the C1 level in magnetic resonance imaging. A computed tomography showed ponticulus posticus (complete type to the right side) with duplication of vertebral artery. She underwent surgical treatment of C1-2 pedicle screw placement and reduction of C1 vertebra under a microscopic view. After C1 laminectomy, both-side vertebral arteries were dissected with a microscissor. The mobilization of upper divisions of vertebral artery was identified to secure the entry point and pedicle to insert a C1 pedicle screw. After complete protection of the upper and lower divisions of vertebral artery and identification of pedicle, a C1 pedicle screw was inserted by a freehand technique. We inserted autologous bone chips in the distracted C1-2 facet joint for facet joint fusion, and the C1 vertebra was pulled out by a rod reducer. After surgery, the patient's symptoms disappeared, and no vertebral artery injury was identified in postoperative 3-dimensional computed tomography angiography. Patient consent was obtained prior to performing the procedure.