Interlabial gap and freeway space at rest position: a cephalometric study

Abstract

Objectives:The aim of this prospective study was to assess the amount of interlabial gap (ILG) and freeway space (FWS) at rest position (RP) according to gender, age, and skeletal pattern, and to evaluate the cephalometric measurements at maximum intercuspal position (MIP) and at RP to define the cephalometric changes from MIP to RP related to the amount of ILG and FWS. Methods: Lateral cephalograms and photographs of selected subjects (47 females, 57 males) were obtained at MIP and RP. Cephalometric measurements at MIP and RP and their differences were measured and compared. Results: ILG (P > 0.05) and FWS (P < 0.01) were greater in males than in females. ILG (P < 0.05) and FWS (P > 0.05) were greater in adolescents than in adults. ILG and FWS were not significantly related with the vertical skeletal pattern (FHR, facial height ratio). ILG was the greatest in Class II cases but without significance. FWS was significantly greater in Class III than in Class I and Class II cases (P < 0.05). At MIP, the ILG at RP increased as overjet (P < 0.05) and upper lip to the aesthetic line (P < 0.01) increased. At RP, the ILG increased as upper incisor exposure and the lips to the aesthetic line increased (P < 0.001), and FWS decreased as overbite decreased (P < 0.001). From MIP to RP, lip length showed the greatest decrease (P < 0.001) in the large ILG group. Additionally, Bjork sum (the sum of the saddle, articular, and gonial angles), mandibular plane angle, anterior facial height, and ANB (P < 0.001) showed the greatest increase, while OB (P < 0.001) showed the greatest decrease in the large FWS group. The lip competent group showed the largest frequency distribution in the small ILG and FWS groups, while smile line frequency distribution showed no relationship with the level of ILG and FWS. Conclusions: Taking cephalometric measurements at RP would be helpful to evaluate the ILG and FWS more accurately, and to provide a more accurate diagnosis and treatment plan.

Evaluación cefalométrica y electromiográfica de niños y niñas con incompetencia labial y anomalías dentomaxilares

“…Hassan y cols, y Seo y cols. han publicado resultados coincidentes en individuos con incompetencia labial (14,15) .…”

“…En cuanto a los resultados de la evaluación en sentido anteroposterior, indican retrusión mandibular y tendencia a clase II esqueletal. Esto está en concordancia con lo observado por diversos autores (15,8,16) .…”

“…y Seo y cols. (14,15) . Por otra parte, el presente estudio determinó un ángulo del incisivo superior en rangos normales, mientras que, otros autores han indicado un aumento en los valores de este ángulo en población con incompetencia labial (5,6) .…”

“…En cuanto a las características observadas en tejido blando y vía aérea los resultados indican la presencia de protrusión bilabial, lo que concuerda con estudios en pacientes con incompetencia labial realizados por distintos autores (15,8,18) . La biprotrusión labial en el caso de pacientes incompetentes labiales podría explicarse por la biprotrusión incisal y por un ángulo interincisivo más agudo que favorecería esta posición labial.…”

“…La estandarización de esta técnica se logró estabilizando la posición de cabeza del paciente mediante un apoyo frontal (15) .…”