Evaluation of the relationship between incisor torque and profile aesthetics in patients having orthodontic extractions compared to non-extractions.

OBJECTIVE: The aim of the present study was to evaluate the relationship between soft tissues aesthetics and incisor torque, as well as the effect of crowding, anchorage, and extraction pattern, in adult patients treated without extraction or with two or four extractions. MATERIALS AND METHODS: Seventy-seven subjects with permanent dentition were selected retrospectively. Among these, 24 patients were treated with four extractions, 24 with two extractions and 29 without extractions. Lateral cephalograms and photographies taken before (T0) and after (T1) treatment were retrieved. The amount of crowding and the type of anchorage were recorded, and a cephalometric analysis was performed. A one-way ANOVA was used to compare the variables within and between groups. Linear regressions were performed to evaluate the effect of different predictors on soft tissues variables at T1. RESULTS: The statistical analysis showed no differences within and between groups for soft tissue aesthetics. A significant reduction of the angle obtained from the intersection of Frankfurt plane and mandibular plane was observed in the four-extractions group, and a significant proclination of the lower incisors was observed in the two-extraction group. Linear regressions revealed that the change in soft tissue profile aesthetics was affected by the type of anchorage and the two-extractions pattern. CONCLUSIONS: Similar soft tissue aesthetics were observed after treatment in the three groups, despite the presence of some skeletal and dental differences. CLINICAL RELEVANCE: A well-controlled incisor torque helps to preserve soft tissues aesthetics. The type of anchorage could influence soft tissues.

Efficacy of upper-incisor torque control with clear aligners: a retrospective study using cone-beam computed tomography.

OBJECTIVES: The objectives of this retrospective clinical study were to evaluate the efficacy of clear aligners on upper-incisor torque control, with the expectation of providing guidance for clinics. MATERIALS AND METHODS: Pretreatment (T0) and posttreatment (T1) cone-beam computed tomography (CBCT) scans of 47 patients with a nonextraction treatment using clear aligners were obtained and 120 upper-incisors with torque ≥5° were selected. Voxel-based superimpositions were performed using Dolphin imaging software and achieved movements were then measured. Difference between achieved and predicted movement (DAPM) and the efficiency for upper-incisor torque were used to evaluate the torque control efficacy. RESULTS: The achieved torque movement with clear aligners was lower than predicted significantly, as the mean efficiency was 46.81±33.95%. Additionally, the achieved incisor movement of the crown and root differed significantly from the predicted movement, especially root movement. CONCLUSIONS: Clear aligners struggle to control upper-incisor torque, particularly root movement. In that case, overcorrection is necessary to prevent torque loss. CLINICAL RELEVANCE: Clear aligners remain a limitation on torque control and overcorrection should be considered.

Cephalometric Evaluation of Maxillary Incisors Torque and Vertical Changes Utilizing Standard Edgewise Mechanics

In 1995 Gebeck & Merrifield studied a successful and unsuccessful treated Class I and Class II's samples; they found a -1.33 mm intrusion in the former and a 0.80 mm extrusion in the latter. The purpose of this article was to perform a cephalometric evaluation of maxillary incisors torque and vertical changes. We studied a sample of 129 patients, 30 males and 99 females, taken from The Charles H. Tweed Foundation Long Term Study, at pretreatment mean age 12.93 years, posttreatment mean age 16.19 years and follow up post retention mean age 29.83 years, a 13.88 years interval. The records were collected from private practitioners across the North American continent who used Standard Edgewise Mechanics and were members of the Charles H. Tweed Foundation. All patients were Class I and II American whites treated with the extraction of 4 premolars. We found an Upper anterior incisal edge to PP vertical linear measurement 28.7 and 29.2 mm, +0.53 mm (p<0.019) from pretreatment to posttreatment. The average Upper 1 to SN angle was 103.2 ° at pretreatment and 100.1° at posttreatment, -3.2° (p<0.000), Upper 1 to PP 111.0° and 108.9°, -2.2° (p<0.000), the three of them statistically significant. Conversely, Upper 1 to commissure was not. The four measurements were also statistically significant posttreatment to follow up, upper anteriors kept losing torque after posttreatment, and less upper anteriors surface was below the commissure. Some torque loss and vertical extrusion can be expected while treating patients with extractions of four premolars, therefore, upper incisor inclination increase and vertical change by itself cannot determine the success of treatment.

En 1995, Gebeck y Merrifield estudiaron muestras de Clase I y Clase II tratadas con éxito y sin éxito; encontraron una intrusión de -1,33 mm en el primero y una extrusión de 0,80 mm en el segundo. El propósito de este artículo fue realizar una evaluación cefalométrica del torque y los cambios verticales de los incisivos maxilares. Estudiamos una muestra de 129 pacientes, 30 hombres y 99 mujeres, tomados del estudio a largo plazo de la Fundación Charles H. Tweed, con una edad media previa al tratamiento de 12,93 años, una edad media posterior al tratamiento de 16,19 años y una edad media de seguimiento posterior a la retención de 29,83 años, con un intervalo de de 13,88 años. Los registros se recopilaron de médicos privados en todo el continente norteamericano que utilizaron Standard Edgewise Mechanics y eran miembros de la Fundación Charles H. Tweed. Todos los pacientes eran blancos americanos Clase I y II tratados con extracción de 4 premolares. Encontramos una medida lineal vertical del borde incisal anterior superior a PP de 28,7 y 29,2 mm, +0,53 mm (p<0,019) desde el pretratamiento hasta el postratamiento. El promedio del ángulo Superior 1 a SN fue de 103,2° en el pretratamiento y 100,1° en el postratamiento, -3,2° (p<0,000), Superior 1 a PP 111,0° y 108,9°, -2,2° (p<0,000), los tres estadísticamente significante. Por el contrario, Superior 1 a la comisura no lo era. Las cuatro mediciones también fueron estadísticamente significativas para el seguimiento después del tratamiento, los dientes anteriores superiores siguieron perdiendo torsión después del tratamiento y se observó menor superficie de los dientes anteriores superiores debajo de la comisura. Se puede esperar cierta pérdida de torque y extrusión vertical al tratar a pacientes con extracciones de cuatro premolares, por lo tanto, el aumento de la inclinación del incisivo superior y el cambio vertical por sí mismos no pueden determinar el éxito del tratamiento.

Lingual orthodontics in an adult patient with upper premolar extraction: Case report.

OBJECTIVE: To show with this case report that lingual orthodontics can be a solution in complex adult situation and with interdisciplinary approach. MATERIALS AND METHODS: The patient presented a dental and skeletal high angle class II division 1 with a previous extraction of one mandibular incisor. The strategy of treatment was upper first premolar-extraction to obtain a correction of the incisal-class II relationship with a normal lip function, a class II molar relationship on the right side and a class I on the left side. A lingual appliance and miniscrews were used. RESULTS: The lingual orthodontic treatment with miniscrews responded to the occlusal objectives with a good upper incisors torque and retraction control. DISCUSSION: Limits and advantages of lingual orthodontics were discussed. CONCLUSION: Lingual mechanics can provide good results from both an aesthetic and function point of view in adult complex extractions case. It ensures aesthetics during treatment, incisor control during retraction. Miniscrews were also useful to overcome the periodontal limits and enhance the anchorage.

Factors related to the control of maxillary anterior teeth torque in invisible appliances / 口腔疾病防治

@#Invisible appliance technology is a novel orthodontic technology that uses computer aided design and polymer materials to achieve a more aesthetic and comfortable treatment. Compared with traditional lip-bracket orthodontic treatments, the greatest advantages of an invisible appliance are aesthetics. In the orthodontic process, the control of the anterior teeth may not be accurate, which often directly affects the patient′s postoperative side appearance; however, in clinical practice, there is still a large deficiency in the control of the anterior tooth torque by an invisible appliance compared to traditional lip-bracket orthodontic treatments. The factors related to the expression efficiency of anterior tooth torque include the combination of morphology and position of different types of brackets and wires, the tooth movement mode and clincheck design. This article reviews the factors that influence lingual orthodontics and clear aligner therapy in the treatment of anterior tooth torque.