Reliability of two techniques for measuring condylar asymmetry with X-rays / Confiabilidad de dos técnicas de medición de asimetría condilar con método radiográfico

Among structural alterations that can be a risk factor for temporomandibular joint disorder (TMD) is condylar asymmetry. In order to measure the condylar asymmetry index in panoramic x-rays quantitatively, two methods have been proposed: those of Habets and Kjellberg. The aim of this study was to determine whether the x-ray method of measuring condylar asymmetries in orthopantomographies presents a minor tendency to error due to slight displacements of the head in the horizontal plane. 30 patients between 18 and 25 years of age were assessed. Each of them underwent three panoramic x-rays in three different positions: orthoradial, and at 5 and 10 horizontal angles. Then the Habets and Kjellberg measurements were taken. Habets' technique did not show any statistically significant differences in the x-rays at 5° and 10° horizontal angles compared to the 0 angle. However, Kjellberg's technique showed statistically significant differences only at the 10° angle compared to the 0 angle. The 10° changes produced linear and ratio variations, but the indices did not vary. It was concluded that both methods provide acceptable clinical information within the limitations of these techniques to obtain data on condylar symmetries or asymmetries of the mandibular body or ramus.

Dentro de las alteraciones estructurales que pueden ser un factor de riesgo de desarrollo de un trastorno temporomandibular (TTM) se menciona a la asimetría condilar. Para realizar la medición cuantitativa del índice de asimetría condilar en radiografías panorámicas se han propuesto dos métodos, Habets y Kjellberg. El objetivo de este estudio fue determinar si el método radiográfico de medición de asimetrías condilares en ortopantomografías que presenta menor tendencia al error por leves desplazamientos de la cabeza en el plano horizontal. Se evaluaron 30 pacientes entre 18 y 25 años de edad. Cada uno de ellos se sometió a tres radiografías panorámicas en tres posiciones distintas: posición ortoradia, 5 y 10 de angulación horizontal. Posteriormente, se realizaron las mediciones de Habets y Kjellberg. La técnica de Habets no mostró diferencias estadísticamente significativas en las radiografías con 5° y 10° de angulación horizontal con respecto al ángulo de 0. Sin embargo, la técnica de Kjellberg mostró diferencias estadísticamente significativas sólo al ángulo de 10° con respecto al ángulo de 0. Las alteraciones de 10° produjeron variaciones lineales y de razones, sin embargo no variaron los índices. Se concluye que ambos métodos entregan información clínica aceptable con las limitaciones que estas técnicas tienen para obtener información sobre simetrías o asimetrías condilares de cuerpo o de rama.

An electromyographic study to assess the minimal time duration for using the splint to raise the vertical dimension in patients with generalized attrition of teeth.

Background: To investigate the effect of restoration of lost vertical by centric stabilizing splint on electromyographic (EMG) activity of masseter and anterior temporalis muscles bilaterally in patients with generalized attrition of teeth. Materials and Methods: EMG activity of anterior temporalis and masseter muscle was recorded bilaterally for 10 patients whose vertical was restored with centric stabilizing splint. The recording was done at postural rest position and in maximum voluntary clenching for each subject before the start of treatment, immediately after placement of splint and at subsequent recall visits, with splint and without the splint. Results: The EMG activity at postural rest position (PRP) and maximum voluntary clench (MVC) decreased till 1 month for both the muscles. In the third month, an increase in muscle activity toward normalization was noted at PRP, both with and without splint. At MVC in the third month, the muscle activity without splint decreased significantly as compared to pretreatment values for anterior temporalis and masseter, while with the splint an increase was seen beyond the pretreatment values. Conclusion: A definite response of anterior temporalis and masseter muscle was observed over a period of 3 months. This is suggestive that the reversible increase in vertical prior to irreversible intervention must be carried out for a minimum of 3 months to achieve neuromuscular deprogramming. This allows the muscle to get adapted to the new postural position and attain stability in occlusion following splint therapy.