The effect of pregnancy on orthodontic tooth movement in rats

Introduction: The purpose of this study was to investigate the effect of pregnancy on orthodontic tooth movement in Wistar rats. Material and Methods: Forty eight female three-month old Wistar rats with an average weight of 250±25 gr were selected and randomly divided into two experimental (pregnant) and control groups (non-pregnant). Maxillary central incisors were tipped distally by insertion of springs exerting 30g force. Two, seven and fourteen days after spring insertion animals were sacrificed. Then the mesioincisal distance between maxillary incisors were measured. Subsequently, histological sections were prepared to count osteoclasts under a light microscope. The data on the extent of orthodontic tooth movement, and the number of osteoclasts were analyzed by independent sample t-test. Results: The results indicated that 2,7 and 14 days after force application there was no significant difference inorthodontic tooth movement between experimental and control groups (p>0.05). The number of osteoclasts were significantly lower in the experimental group 7 and 14 days after spring insertion (p<0.05).Conclusion: Pregnancy may decrease the amount of tooth movement in the linear phase but it is not statistically significant. The number of osteoclasts is significantly decreased during pregnancy (AU)

Estudio comparativo in vitro entre la instrumentación manual con limas de acero inoxidable y la instrumentación rotatoria con limas de níquel-titanio en cuanto al transporte apical en conductos curvos / An in vitro comparison of apical transportation in curved root canal preparations with hand stainless steel and nickel-titanium rotary instrumentation

Objetivos: En este estudio se pretende valorar el grado de enderezamiento de los conductos radiculares que se obtiene tras la instrumentación de éstos con limas manuales de acero y con limas rotatoria de Ni-Ti. Material y métodos. Para ello seleccionamos 30 molares inferiores y calculamos el grado de curvatura de cada uno de los 2 conductos mesiales mediante la técnica de Schneider. A continuación instrumentamos el conducto mesiovestibular con limas K de acero inoxidable y técnica de step-back; y el mesiolingual con el sistema rotatorio de limas Ni-Ti Hero Shaper@ según indicaciones del fabricante. Tras la instrumentación volvimos a calcular la angulación de los conductos con la misma técnica. Resultados. Los resultados mostraron que hubo menor transporte apical en el grupo de limas Ni-Ti que en el grupo de limas de acero con una diferencia estadísticamente significativa (p<0,05). Conclusiones: Por ello, pese a que ambas técnicas provocan una deformación del conducto, se recomienda usar en conductos curvos una instrumentación rotatoria con limas Ni-Ti (AU)

Aim: The purpose of this study was to determine the extent to which root canals were straightened after their preparation with hand stainless steel K-files and with rotary Ni-Ti files. Material and methods. Thirty mandibular molars were selected and the degree of root curvature was calculated in each of the two mesial canals, using the Schneider technique. Following this, the mesiobuccal canals were cleaned with stainless steel K-files and step-back technique, and the mesiolingual canals were cleaned with Ni-Ti Hero Shaper® rotary files according to the manufacturer´s instructions. After preparation, the angle of the canals was re-calculated in the same way as before. Results. The results showed that there was less apical transportation in the Ni-Ti files group than in the stainless steel one, with a statistically significant difference (p<0,05). Conclusion: In spite of both techniques cause canal deformation, it is recommended to use Ni-Ti files in curved canals (AU)

Biomechanical aspects of external root resorption in orthodontic therapy

No disponible

External apical root resorption is a common phenomenon associated with orthodontic treatment. The factors relevant to root resorption can be divided into biological and mechanical factors. Some mechanical and biological factors might be associated with an increased or decreased risk of root resorption during orthodontic treatment. For mechanical factors, the extensive tooth movement, root torque and intrusive forces, movement type, orthodontic force magnitude, durationand type of force are involved. For biological factors, a genetic susceptibility, systemic disease, gender and medication intake have been demonstrated influence root resorption. Orthodontic therapy of patients with increased risk of root resorption should be carefully planned. Medical history, medication intake, family history, tooth agenesis, root morphology,oral health and habits must be considerate if we do not want jeopardize our patients by severe root resorption. To monitor apical root resorption the standard procedure is a radiographic examination after 6 months of treatment. In teeth with enhanced risk, a 3-month radiographic follow-up is recommended. The administration of anti-inflammatory drugs might suppress root resorption induced by orthodontic therapy, although none study was enough conclusive to indicate a protocol for patients with enhanced risk. In the event of multiple external root resorption, the diagnosticprocedure should focus on the exclusion of the local factors and its associations (such as magnitude, duration and type of orthodontic force; periodontal disease; root form) that might lead to external root resorption. Systemic disorders associated with phosphorus-calcium metabolic alterations shall be suspected. This review searched the current knowledgeof the mechanical and biological aspects of root resorption in orthodontic tooth movement

Opciones de tratamiento. Presentación del caso: Mujer, 35 años y 6 meses / No disponible

Se presenta una paciente de 35 años y 6 meses con relación molar-canina de clase 11, resalte horizontal aumentado, apiñamiento severo y diagnosticada de enfermedad periodontal severa (AU)

No disponible

Opciones de tratamiento. Así fue tratado: Mujer, 35 años y 6 meses / No disponible

No disponible

Rotaciones de los dientes permanentes en la clínica de ortodoncia / No disponible

Introducción. El objetivo de este estudio es medir la frecuencia e intensidad de las rotaciones en incisivos y caninos permanentes y premolares, superiores e inferiores, y relacionarlas con variables biométricas como anchura intercanina e intermolar, tamaño dentario y discrepancia de longitud de arcada. Material y métodos. Se realizó un estudio observacional retropectivo utilizando modelos de estudio de 50 casos no tratados ortodóncicamente y elegidos al azar. Se requería la presencia de todos los dientes permanente de primer molar a primer molar y la ausencia de agenesias o supernumerarios. Se midieron las rotaciones de cada diente, diámetro mesiodistal, anchuras intercanina e intermolar y discrepancia de longitud de arcada superior e inferior. Para el análisis estadístico se determinó la media, desviación típica e intervalo de confianza del 95% para la media de las magnitudes estudiadas; la prueba de la de Student y el ANOVA con prueba de Tukey para la comparación de 2 y 3 medias respectivamente, y el coeficiente de correlación r-Pearson. Resultados. El porcentaje de dientes rotados en cada tipo de diente osciló entre 48 y 82% y no se encontraron diferencias estadísticamente significativamente mayores que el resto, del 80 y 82% respectivamente. No se encontró dimorfismo sexual ni bilateral, ni correlaciones significativas entre las rotaciones y las variables biométricas, excepto entre la discrepancia de longitud de arcada superior negativa y el número de dientes rotados en dicha arcada (r=-0,327; p<0,05) (AU)

Introduction. The aim of this study is to measure rotation frequency and intensity in upper and lower permanent incisive, permanent canines, and bicuspids, and to relate them to biometric variables such as intercanine and intermolar width, tooth size and arch length discrepancies. Material and methods. Retrospective observation was made using study catss of 50 orthodontically untreated cases selected at random. The presence of all permanent teeth from the first molar to the other was a pre-requesite, as was the absence of agenesis or supernumerary. Measurements of the rotation of each tooth, mesidistal diameter, intercanine and intermolar width, and upper and lower arch length discrepancies were taken. The statistical analysis consisted of determining mean, standard deviation, with a 95% confidence interval for the mean of the values under study. Student T test and ANOVA using Tukey test to compare 2 and 3 means respectively; and r-Pearson correlation coefficient. Results. The percentage of rotated teeth for each type fluctuated between 48$ and 82% with no statistically significant differences between them being found, except for teeth 3.3 and 4.2 which revealed significantly higher frequencies than the remainder. 80% and 82% respectively. No sexual or bilateral dimorfism were found, except for upper arch length discrepancy with a negative value and the number of rotated teeth in the upper arch (r=-0.327; p<0.05)