Comparing sella turcica shapes and dimensions in skeletal classes I, II and III bimaxillary protrusion patients in a Nigerian population

Abstract

BACKGROUND: Bimaxillary protrusion is a common type of malocclusion seen in Africans with marked protrusion of the maxillary and mandibular incisors and an increased procumbency of the lips. Management involves cephalometric radiographic evaluation and comparison with other structures within the skull. The sella turcica is one of these radiographic landmarks used in determining orthodontic parameters for management. The shape and dimensions in these patients may be affected as a result of the bimaxillary protrusion.

OBJECTIVE: The aim of this study was to evaluate sella turcica shapes and dimensions in skeletal classes I, II and III bimaxillary protrusion patients in a Nigerian population

STUDY DESIGN: This study was carried out at the Orthodontic unit of the University of Benin Teaching Hospital, Benin City Nigeria. Lateral Cephalometric radiographs of 64 patients (28 male and 36 female) with bimaxillary protrusion (interincisal angle of ≤107°) in the three skeletal classes was evaluated. Linear dimensions (length, depth and antero-posterior diameter) were measured. The student t-test was used to calculate the difference in linear dimensions. The one way analysis of variance (ANOVA) was done to study the relationship between sella turcica types, size, skeletal class and bimaxillary proclination.

RESULTS: The mean interincisal angle was 100.16°±7.004. Bimaxillary protrusion was seen in classes I, II and III skeletal patterns in 28(43.7%), 33(51.6%) and 3(4.7%) respectively. Six shapes of sella turcica were identified with the normal shape most prevalent in bimaxillary protrusion skeletal class II (52.4%) and absent in the oblique anterior wall shape in bimaxillary protrusion skeletal Class III. The double contour shape was also absent in bimaxillary protrusion skeletal classes I and III. The mean length (9.932±2.14mm), depth (6.96±1.88mm) and diameter (9.30±1.41mm) were determined. The dimensions of the sella turcica were longest in class III with mean values of 10.67mm ± 0.577 (length), 7.83mm ±2.466 (depth) and 10.0mm ±1.732 respectively.

CONCLUSION: Bimaxillary protrusion patients exhibit a mean interincisal angle of 100.16°; various shapes of the sella turcica also exist for bimaxillary protrusion classes I, II and III respectively.