Shmuli T, Wasserstein A, Turgeman R, Brezniak N
Refuat Hapeh Vehashinayim (1993). 2014 Jul;31(3):26-30, 60-1.
The light reflection zone (LRZ) is a new parameter that may serve as a tool for the diagnosis of smile esthetics. It is a bright white dot or area that appears on the surface of the maxillary central incisors and/or the gingiva of the front teeth, visible in intra-oral and smile extra-oral photographs. Recently it was found that the general population defines a nicer smile when the LRZ is located in the gingival area of the upper central incisors' surface rather than the incisal third. The aim of this study was to find out in two populations that are not aware of this new parameter, laypersons and orthodontists, whether there is a difference in the identification of the LRZ and the importance of the LRZ in determining the quality of the smile. Twelve pairs of facial photographs, including 10 of ordinary smiling persons and 2 of smiling models, were presented to 108 laypersons and 30 orthodontists. The only difference between each pair was the location of the LRZ that was moved, compared to the original photograph, gingivally or incisally respectively, using Photoshop (Adobe). Each participant was asked to mark whether he/she noticed a difference between the 2 pictures, and if so, to score the nicer smile. Data analysis was carried out using Chi square test and Fisher's exact test (SPSS v17). The results showed that both populations had difficulty in recognizing the differences between the pictures that were based solely on the LRZ parameter. However, when differences were recognized, most of the participants in both populations pointed on the smile where the LRZ was located gingivally as the nicer one. The orthodontic population recognized the difference between the two pictures, in which only the LRZ was changed, to a lesser extent compared to the laypersons populations. This result was with statistical significance (p = 0.007).
光反射区（LRZ）是一个新参数，可作为诊断微笑美学的一种工具。它是出现在上颌中切牙表面和/或前牙牙龈上的一个亮白色点或区域，在口腔内照片和微笑的口外照片中可见。最近发现，当光反射区位于上颌中切牙表面的牙龈区域而非切缘三分之一处时，普通人群会认为这样的微笑更美观。本研究的目的是在不了解这一新参数的两类人群——外行人与正畸医生中，探究他们在识别光反射区方面是否存在差异，以及光反射区在确定微笑质量中的重要性。向108名外行人与30名正畸医生展示了12对面部照片，其中包括10张普通微笑者的照片和2张微笑模特的照片。每对照片之间的唯一差异是光反射区的位置，使用Photoshop（Adobe）软件将其相对于原始照片分别向牙龈方向或切缘方向移动。要求每位参与者标记他/她是否注意到两张照片之间的差异，如果注意到了，对更美观的微笑进行评分。使用卡方检验和费舍尔精确检验（SPSS v17）进行数据分析。结果显示，两类人群都难以识别仅基于光反射区参数的照片之间的差异。然而，当识别出差异时，两类人群中的大多数参与者都指出光反射区位于牙龈处的微笑更美观。与外行人相比，正畸医生群体识别出仅光反射区发生变化的两张照片之间差异的程度较小。这一结果具有统计学意义（p = 0.007）。
