Medición del ángulo vestíbulo-lingual en conductos mesiales de primeros molares inferiores utilizando tomografía de haz cónico / Measuring the vestibular-lingual angle in lower molar first mesial ducts using cone beam tomography

El objetivo del presente estudio fue medir la curvatura vestíbulo-lingual de los conductos de las raíces mesiales de primeros molares inferiores en personas adultas del estado de Chihuahua, por medio de la técnica de tomografía computarizada de haz cónico (CBCT, por sus siglas en inglés) y usando el software de análisis 3D EndoTM (Dentsply/Sirona USA). Se llevó a cabo la medición por dos observadoras, empleando dos métodos diferentes, Schneider y 3D EndoTM (Dentsply/Sirona USA). Los resultados obtenidos tuvieron valores mayores a los 100 grados con la técnica 3D EndoTM y a los 20 grados con la técnica de Schneider. No se detectó una diferencia estadística significativa al comparar los diferentes conductos entre sí (AU)

The objective of the present study was to measure the vestibule-lingual curvature of the ducts of the mesial roots of lower first molars, of adults from the state of Chihuahua. Using the cone beam computed tomography (CBCT) technique and using the 3D analysis software EndoTM (Dentsply/Sirona USA). The measurement was carried out by two observers using two different methods, Schneider and 3D EndoTM (Dentsply/Sirona USA). The results obtained had values greater than 100 degrees with the 3D EndoTM technique and at 20 degrees with the Schneider technique. No statistically significant difference was detected when comparing the different ducts with each other (AU)

Consideraciones Metodológicas en el Estudio Histomorfométrico del Hueso Interradicular de los Primeros Molares Inferiores de Ratas Wistar / Methodological Considerations in the Histomorphometric Study of the Interradicular Bone of the First Lower Molars of Wistar Rats

El objetivo fue evaluar el volumen óseo BV/TV (%) del hueso interradicular en ratas Wistar: A) en relación a la edad; B) en relación a la zona de estudio en animales de la misma edad. Se utilizó Grupo A) 15 ratas Wistar hembras de 6 (I), 10 (II) y 14 (III) semanas, Grupo B) 9 ratas Wistar macho de 8 semanas. Tras la eutanasia, se extrajeron los maxilares inferiores y se procesaron histológicamente para obtener cortes mesio-distales del primer molar inferior coloreados con H.E. Sobre microfotografías digitales se evaluó el BV/TV (%). El análisis estadístico se realizó en A) mediante ANOVA y Bonferroni test y en B) se calculó el rango (R). Los resultados en A) el BV/TV (%) aumenta significativamente con la edad de los animales; en B) se encontró que el BV/TV (%) varía hasta un 20% si se considera el volumen total y este rango disminuye a 8.3% al estudiar su mitad coronal. En conclusión, el BV/TV (%) del hueso interradicular del primer molar inferior de ratas Wistar varía considerablemente con la edad de los animales y en animales de una misma edad -según se considere evaluar todo el hueso interradicular del espacio alveolar o la mitad superior del mismo-. Los resultados de este trabajo recomiendan emplear animales de la misma edad y realizar mediciones histomorfométricas empleando la mitad coronal de dicho hueso, especialmente en los diseños de periodontitis experimental (AU)

Changes in occlusal force depending on the movement of the adjacent and opposing teeth after loss of lower first molar: comparative study by using a strain gauge

PURPOSE: The aim of this study was to investigate the changes in occlusal force after loss of the lower first molar depending on the inclination and extrusion of the adjacent and opposing teeth by using a strain gauge. MATERIALS AND METHODS: Anatomic teeth were used to reconstruct the normal dental arch with loss of the lower right first molar. A uniformly thick layer of silicone was applied to the root to mimic the periodontal ligament. Four stages of dies with varying degrees of inclination and extrusion of the adjacent and opposing teeth were constructed and attached to master model interchangeably by using a CAD/CAM fabricated customized die system. The strain gauges were attached to teeth and a universal testing machine was used to determine the changes in occlusal force. An independent t-test and one-way ANOVA were performed (α = .05). RESULTS: While simulating chewing food, the upper first, second premolar and lower second molar showed greater occlusal force than before extraction. When the change of adjacent teeth's occlusal force with their progressive movement after molar loss was evaluated, the difference among four die models was significant and was in the decreasing aspect (P < 0.05). CONCLUSION: When the lower first molar was lost and the adjacent teeth did not move yet, the occlusal force in adjacent teeth was higher than that when the lower first molar still existed. In addition, the occlusal force in the upper premolars and lower second molar decreased significantly with the progressive movement of adjacent teeth.

Incidencia de las extracciones del primer molar inferior permanente en los ruidos articulares / Permanent lower first molar extraction incidence in articular noises

Los ruidos articulares se presentan frecuentemente en la práctica diaria odontológica, algunos son audibles a simple oído y en otros casos es necesario tener entrenado el oído ya que pueden resultar imperceptibles. Mediante un examen clínico y desarrollo de un protocolo destinado especialmente para la articulación temporomandibular (ATM), los odontólogos registraron los datos en fichas individuales. Además se registraron los datos relacionados con la frecuencia de aparición según el sexo y la edad. Los resultados demostraron que la extracción prematura del primer molar inferior permanente no incide en la aparición de ruidos articulares.

Articular noises are frequently present in the daily dental practice. Some are easily discernible, nevertheless, in some other cases a trained ear might be necessary to perceive them since they might be imperceptible. In the present study, by means of a physical examination and development of a specifically TMJ-designed (temporomandibular joint) protocol dentists recorded data in individual files. Data related to onset frequency according to age and gender were equally recorded. Results revealed the fact that premature extraction of the permanent lower first molar did not bear influence on the onset of articular noises.

Study on the eruption of the lower third molar in the cases of non-extraction and the extraction of first premolar / 대한치과교정학회지

This study was designed to recognize the factors which can affect the normal eruption of the lower third molar and the eruption rate of the lower third molar in the cases of non-extraction and the extraction of first premolar. The sample consisted of 214 cases of extraction of first premolar and 119 cases of non-extraction, and all of these cases were divided into erupted and impacted lower third molar groups and were analized according to the pantomogram. The results of the study were as follows : 1. The eruption rate of the lower third molar was 54.67 % in the group of extraction of the first premolar and 35.29 % in the non-extraction group. 2. The early inclination of the erupting lower third molar has significant effect in the eruption of it. 3. In the orthodontic treatment, the extraction of first premolar is one of the factors influencing the normal eruption of lower third molar. 4. The available space for the normal enruption of lower third molar was greater in first premolar extraction case than in non-extraction case.