Primary failure of eruption: occlusal and dentoalveolar characteristics in mixed and permanent dentition. A study with cone beam computed tomography.

Background: The main objective of this study was to describe the dentoalveolar and occlusal characteristics of subjects with primary failure of eruption (PFE) in cone beam computed tomography (CBCT) and compare them with a control group without the anomaly. Material and Methods: This retrospective and comparative study evaluated CBCT images of 80 permanent molars divided into 2 groups of 40 molars each, which had or did not have PFE characteristics. Using CBCT a calibrated orthodontist performed 23 measurements related to the distances of the cusps to the occlusal, palatal and mandibular planes and measured the buccal-palatal and mesiodistal widths of the molar crowns and their root lengths. Independent Student's t or Mann-Whitney U tests were used to compare occlusal and dentoalevolar characteristics between groups according to the normality of the data. P<0.05. Results: Molars affected by PFE were smaller in coronal dimensions in the PFE compared to the non-PFE group (Buccal-palatal crown width 11.60±0.95mm vs. 12.21±1.09 mm; p<0.001; and mesiodistal crown width 10.81± 1.07 mm vs. 11.84±1.32mm, respectively; p<0.001). The distal and mesial root lengths were approximately 2 mm smaller in the PFE group (p<0 .001). The three-dimensional bony position was more convergent with respect to the palatal plane, i.e., the crown was more inclined palatally and distally in the PFE compared to the non-PFE group. Conclusions: Patients with molars affected by PFE present smaller bucco-palatal, mesio-distal coronal widths and mesial and distal root lengths than those without PFE and in these teeth the crowns are more inclined palatally and distally in upper molars. These specific characteristics may be pathognomonic of PFE and should be considered by clinicians when evaluating or treating patients with this condition. Key words:Occlusal characteristics, primary failure of eruption, cone-beam CT.

Multiple eruptive delay as a variant of primary eruption failure. A preliminary case report.

Primary failure of eruption (PFE) is an autosomal disease that occurs in approximately 0.06% of the population and is defined as the malfunction of dental eruptive mechanisms with delay and absence of these processes in a non-ankylosed tooth. Treatment options for patients with eruptive delays range from prosthetic to surgical interventions. Although this condition is relatively rare, the occurrence of eruptive disorders in clinical dental practice is becoming more frequent. Correct diagnosis of this eruptive anomaly plays an essential role in treatment planning. The aim of this case report was to describe the treatment of a case of multiple PFE with a biomechanical approach to extrusive traction using NiTi closed coil springs and a customized rigid anchorage. In conclusion, complex orthodontic cases with eruptive delay and variants of PFE can be successfully intervened to make morphologically and functionally compromised dental organs viable, if diagnosed and treated in a timely and preventive manner by a multidisciplinary approach using alternative biomechanics for efficient osteogenic traction.