Nouh Abdallah S, Abdel Majeed H M, Nassef Selim Essam Mohamed
Nuclear and Radiological Regulatory Authority, (NRRA), P.O. 7551, Nasr City, Cairo, Egypt.
Department of Orthodontics, Faculty of Oral and Dental Medicine, Future University, Cairo, Egypt.
J Orthod Sci. 2021 Oct 15;10:18. doi: 10.4103/jos.JOS_79_20. eCollection 2021.
Esthetic enhancement plays an important role in orthodontic treatment. This study was conducted on females as most girls have their growth spurt at a younger age than boys do, so their demand to facial esthetics, especially those who have residual growth of mandible producing class III effect, requires full understanding to smile features helping in diagnosis and treatment planning for maximum patient satisfaction.
This study was conducted on 30 skeletal Class III and Class I female adults (18-30 years old) who were divided equally into two groups comprising 15 each. Two frontal digital photographs were taken for each subject, one at rest and the other in the posed smile position. Photographs were taken for each subject in the natural head position by a Canon EOS 1200 D camera set on a tripod at a distance of 1.5 m. The incisogingival height of the right maxillary central incisor was clinically measured using a vernier caliper to the nearest 0.1 mm. Photographs were uploaded on Photoshop software for standardization and then uploaded on the Digital Smile Design software (DSD) where the actual incisogingival height of the central incisor was used for automatic calibration. Esthetic components at rest and on smiling were measured for both groups; all linear variables were measured to the nearest 0.1 mm.
Class III females tended to have wider smile widths, less gingival display, longer chin heights, shorter lower vertical dimensions, and a higher percentage of nonconsonant and flat smile arcs than Class I subjects.
The components of the smile should be considered as a guide to help in planning and designing the mechanics during comprehensive orthodontic treatment.
美观改善在正畸治疗中起着重要作用。本研究以女性为对象，因为大多数女孩的生长突增期比男孩早，所以她们对面部美观的需求，尤其是那些下颌有残余生长导致Ⅲ类错牙合效应的女孩，需要充分了解微笑特征，以辅助诊断和治疗计划制定，从而实现患者满意度最大化。
本研究选取了30名骨骼Ⅲ类和Ⅰ类成年女性（18 - 30岁），将她们平均分为两组，每组15人。为每位受试者拍摄两张正面数码照片，一张是休息时的照片，另一张是摆好微笑姿势时的照片。使用佳能EOS 1200 D相机，将其安装在三脚架上，在距离受试者1.5米处，以自然头位为每位受试者拍照。使用游标卡尺临床测量右上颌中切牙的切龈高度，精确到最接近的0.1毫米。将照片上传到Photoshop软件进行标准化处理，然后上传到数字微笑设计软件（DSD）中，使用中切牙的实际切龈高度进行自动校准。测量两组受试者休息时和微笑时的美学成分；所有线性变量均测量到最接近的0.1毫米。
与Ⅰ类受试者相比，Ⅲ类女性往往微笑宽度更宽、牙龈暴露较少、颏部高度更长、下颌垂直距离更短，并且非协调和平坦微笑弧度的比例更高。
在全面正畸治疗过程中，微笑的各个组成部分应被视为辅助治疗计划制定和力学设计的指南。
