RESUMEN
Excessive orthodontic force can induce inflammatory tooth root resorption due to sustained high stresses within the periodontal ligament (PDL). This study aimed to analyze the PDL pressures during upper incisor retraction using the en masse method with TISAD. The finite element method (FEM) ensured consistent conditions across cases. The models included bone geometry, adjacent teeth, PDL, and orthodontic hardware, analyzed with LS-Dyna. The pressure ranged from 0.37 to 2.5 kPa across the dental arch, with the central incisors bearing 55% of the load. The pressure distribution remained consistent regardless of the force or hook height. The critical pressure (4.7 kPa) was exceeded at 600-650 g force, with notable pressure (3.88 kPa) on the palatal root wall of the right central incisor. Utilizing 0.017 × 0.025 SS archwires in MBT 0.018 brackets provided good torque control and reduced the root resorption risk when forces of 180-200 g per side were applied, maintaining light to moderate stress. Triple forces may initiate resorption, highlighting the importance of nonlinear finite element analysis (FEA) for accurate oral cavity simulations.
RESUMEN
Linguoverted mandibular canines are relatively rare among craniofacial abnormalities, and they are an isolated anomaly. They are most often caused by non-genetic factors such as persistent deciduous canine teeth or trauma coinciding with the eruption of permanent teeth. Another factor may be mandible narrowing or underdevelopment in the transverse dimension and vestibular inclination of the maxillary canine teeth. This article presents a procedure based on three cases where the position of the mandibular canine tooth was corrected using human orthodontic appliances modified to affect the canine dental system. The incline of the appliance was made to stimulate the protrusion of the mandible while the teeth were closing. After approximately 4 weeks, the lower canine teeth moved along the incline of the appliance, and tilt toward the flews was achieved.
RESUMEN
The goal of this paper was to present the orthodontic treatment of a patient with unilateral lip, alveolar and hard palate cleft (UCLP) and the agenesis of permanent teeth and prosthetic rehabilitation of two cases differing from each other in the extent of tissue deficiency. Both patients underwent a long, multi-specialist surgico-orthodontic treatment including derotation of the maxilla's smaller segment and restoration of space for the missing teeth. In the first case presented, cross-bite on the front teeth and the canine was eliminated during a late phase of orthodontic treatment in order to prepare for final prosthetic rehabilitation. Two prosthetic restorations in patients with similar dental anomalies (hypodontia of the right upper incisors) were presented and discussed in detail. Prosthetic rehabilitation with cemented restoration was carried out after the end of growth. Satisfactory function of the orthognathic system and face appearance were accomplished. In both cases cemented prosthetic restorations preserve the treatment outcome and bite stability. The results were excellent and satisfying for the patients. The patient who presented more extensive tissue distortion has retained correct bite and prosthetic restorations for 20 years. The patient whose correction of the malocclusion and the cemented prosthetic restoration was completed is also predicted to maintain long-standing oral health and good functioning of the masticatory system.