Identifying position, visibility, dimensions, and angulation of the ear.

INTRODUCTION Proportional evaluation of the face has its origin in the 17th and 18th centuries in the neoclassical canons of facial proportion by artists and anatomists [1]. Many Renaissance artists believed that facial beauty was rooted in balanced proportions and facial symmetry [2]. The relationship between size and proportion of different facial measurements is considered to affect the perception of aesthetics. The growth of prosthodontics has enabled the restoration of patients with maxillofacial defects. An important aspect of successful rehabilitation is the positioning of any prosthesis on the face [3]. The ear prosthesis presents several challenges to the clinician. Regardless of the treatment plan selected for unilaterally missing ear, the existing ear's dimensions, position, level, and prominence must be measured to predict the seating and shaping of the final ear prosthesis [4], but no such guide exists for bilateral missing ear. To overcome this situation, reliable techniques are required wherein facial measurements could be used as a guide during fabrication of a prosthesis. Manual anthropometry, two-dimensional photography, and three-dimensional photogrammetry were the three most widely used methods for facial measurements [5]. Anthropometry has been shown to be useful in orthodontic research and in reconstructive surgery, where the soft tissue morphology of the face can be studied more reliably than from radiographs [6]. Currently, more than 20 landmarks and parameters are being used in the medical and dental professions for facial measurements to correlate with ear landmarks. In addition, use of a reference plane is also considered to be critical in planning the position of the prosthetic ear [3]. The use of anthropometric measurements coupled with an established reference plane will help in more accurately determining the prosthetic site. This technique seemed to be more accurate than the use of anthropometric points alone [3]. Recently, computerized tomography, magnetic resonance imaging, and laser scanning techniques have also been used to measure the dimensions and position of the ear [3-4]. Studies with comprehensive guidance in designing bilateral ear prostheses are limited to date. The present study assessed ear position with a reference plane indicator, angulations of the ear in relation to nose, visibility from the frontal view, and dimensions of the ear by using various anthropometric points of the face. METHODS We selected 254 subjects of Southeast Asian origin, both male and female because sex-dependent differences in adolescents and young adults are minimal [7]. The subjects were selected so as to cover four facial form types as postulated by Leon Williams' classification (square, square tapering, ovoid, and tapering) [8]. To minimize the effect of aging on the facial proportion, subjects were between the ages of 18 and 30 yr [7,9-10]. Care was taken to avoid subjects with gross facial asymmetries, history of facial trauma and surgery, and mixed parental ethnicity. Convenience sampling was used for the selection of the sample. [FIGURE 1 OMITTED] Subjects were divided into four groups based on facial form by the concurrence of two experienced prosthodontists, and facial measurements were recorded using anthropometric points of the face. Detailed descriptions of anthropometric points are diagrammatically represented in Figure 1. For vertical/horizontal measurement of the face and identification of ear angulation, neoclassical canons were also used. For standardization, only the right ear was used to measure the dimensions, visibility, and angulation because, according to Barut and Aktunc [11], dimensions difFer between the right and left ears. To identify the position of the ear, a specially designed reference plane-indicating device was used. This device, consisting of a metal frame with two metallic rulers attached, was designed to determine the superior-inferior positioning of the ear (Figure 2). …