Comparison of orthodontic root resorption of root-filled and vital teeth

Trabecular Bone Component Assessment under Orthodontic Loads and Movements during Periodontal Breakdown-A Finite Elements Analysis

This numerical analysis, by employing Tresca and Von Mises failure criteria, assessed the biomechanical behavior of a trabecular bone component subjected to 0.6, 1.2, and 2.4 N orthodontic forces under five movements (intrusion, extrusion, tipping, rotation, and translation) and during a gradual horizontal periodontal breakdown (0-8 mm). Additionally, they assessed the changes produced by bone loss, and the ischemic and resorptive risks. The analysis employed eighty-one models of nine patients in 405 simulations. Both failure criteria showed similar qualitative results, with Tresca being quantitatively higher by 1.09-1.21. No qualitative differences were seen between the three orthodontic loads. Quantitatively, a doubling (1.2 N) and quadrupling (2.4 N) were visible when compared to 0.6 N. Rotation and translation followed by tipping are the most stressful, especially for a reduced periodontium, prone to higher ischemic and resorptive risks. In an intact periodontium, 1.2 N can be safely applied but only in a reduced periodontium for extrusion and intrusion. More than 0.6 N is prone to increasing ischemic and resorptive risks for the other three movements. In an intact periodontium, stress spreads in the entire trabecular structure. In a reduced periodontium, stress concentrates (after a 4 mm loss-marker for the stress change distribution) and increases around the cervical third of the remaining alveolar socket.

The consequences of orthodontic extrusion on previously intruded permanent incisors-A retrospective study

AIM

The aim of this study is to compare the adverse effects that occur after orthodontic extrusion of teeth that have been traumatically intruded with those of similar teeth that have not experienced any trauma.

BACKGROUND

The outcome of incisors intrusion can be affected by the patient's age, extent of injury, root development, and malocclusion. Orthodontic extrusion is a potential solution, but it may also cause complications.

MATERIALS AND METHODS

A retrospective study of the effects of extrusion of traumatically intruded teeth was carried out. The study group included 21 teeth in 14 patients. The control group included 32 teeth in 10 patients that underwent orthodontic extrusion with no history of trauma. Patients' age, gender, and stage of root development were recorded. The severity of the intrusion was classified as mild (<3 mm), moderate (3-6 mm), and severe (≥7 mm). A comparison of signs of pulp necrosis and root resorptions between the groups was made.

RESULTS

The central incisor is the tooth that is most injured in 80.9% of cases. A majority of these incidents involve severe intrusion, which was found in 42.9% of cases. 90% of the traumatized teeth had already lost their vitality prior to orthodontic treatment. Various forms of root resorption were observed in the study group. In the control group, 31.2% of teeth showed signs of external root resorption, but no endodontic intervention was carried out during the follow-up period, as these teeth remained vital.

CONCLUSIONS

Following intrusion, there is a high risk for root resorption and pulp necrosis. Orthodontic repositioning should be carried out with caution and mild force to prevent complications. Long-term follow-ups are required to ensure the best possible outcome.

Root Surface Changes in Endodontically Treated Teeth Following Orthodontic Movement

INTRODUCTION

Orthodontically induced external root resorption (OIERR) has been labeled an unavoidable consequence of orthodontic tooth movement (OTM). The objective of this study was to investigate the change in surface area (mm²) and volume (mm³) of endodontically treated teeth (ETT) compared to contralateral teeth with a vital pulp (VPT) following OTM.

METHODS

Seventy-six teeth were included in this retrospective analysis: ETT (n=38) and VPT (n=38). All teeth were evaluated using CBCT imaging at two time periods: before OTM (T1) and after OTM (T2). Study teeth were segmented to include all areas contained within the lamina dura and then were converted into a mesh model for data calculation. The surface area (mm²) and volume (mm³) of each tooth was calculated at T1 and T2 based on the number of cubic voxels present within the mesh model. Statistical analysis was performed using a linear mixed-effects model.

RESULTS

The average change in surface area following OTM in ETT was 13.01 mm², and 19.95 mm² in VPT (p<0.05). The average percent change in surface area following OTM in ETT was 2.09%, and 3.38% in VPT (p<0.05). The average change in volume following OTM in ETT was 22.48 mm³, and 32.44 mm³ in VPT (p<0.05). The average percent change in volume following OTM in ETT was 2.62%, and 4.10% in VPT (p<0.05).

CONCLUSIONS

The results from this study suggest that ETT are less susceptible to root resorption following OTM than their vital counterparts.