杨大鹏 丁士育 李培培 员丽影

[摘要]目的：探究唐山地區年龄为10岁处于混合牙列期正常牙合青少年下颌牙弓及下颌双侧第一磨牙在三维方向上的生长发育变化。方法：对唐山地区某小学年龄为10岁的正常牙合青少年进行筛选，按照标准筛选出研究样本40例（男20例，女20例）。每年取石膏模型一副，连续跟踪两年，应用3-shape扫描仪扫描石膏模型，将其转化为数字模型。在数字模型上进行牙弓及第一磨牙三维方向上的生长发育变化的研究。结果：过去两年中，下颌前部牙弓长度（LAAL）增加了0.556mm，下颌全部牙弓长度（LTAL）增加了2.067mm，下颌乳尖牙或恒尖牙间牙弓宽度（LICW）增加了2.904mm，下颌第一磨牙间牙弓宽度（LIMW）增加了2.172mm。年龄为12岁的男性LIMW大于女性。右下第一磨牙颊舌向倾斜度（LR6BL）和左下第一磨牙颊舌向倾斜度（LL6BL）分别增加了2.841°和5.410°。结论：10～12岁正常牙合青少年的下颌前部牙弓长度（LAAL）、下颌全部牙弓长度（LTAL）、下颌乳尖牙或恒尖牙间牙弓宽度（LICW）、下颌第一磨牙间牙弓宽度（LIMW）均随年龄增长而增加。年龄为12岁的男性第一磨牙间牙弓宽度均大于女性。下颌双侧第一磨牙随年龄的增加呈颊向倾斜，而近远中向倾斜度无明显变化。年龄为12岁的男女下颌第一磨牙的近远中和颊舌向倾斜度无性别差异。

[关键词]正常牙合;下颌牙弓宽度;下牙弓长度;下颌第一磨牙颊舌向倾斜度;下颌第一磨牙近远中向倾斜度;混合牙列期;3D数字模型

[中图分类号]R78    [文献标志码]A    [文章编号]1008-6455（2021）07-0098-05

Study on Three-dimensional Growth and Development of Mixed Dentition Lower Dental Arch and Bilateral First Molar of Teenagers with Normal Occlusion in Tangshan City

YANG Da-peng1，DING Shi-yu2，LI Pei-pei1，YUN Li-ying1

（1.Department of Orthodontics，Tangshan Union Medical college Hospital，Tangshan 063000，Hebei，China;2.Department of Stomatology，Tangshan Vocational & Technical College，Tangshan 063000，Hebei，China）

Abstract： Objective  The purpose of this study was to observe the three-dimensional growth and development of the mandibular dental arch and bilateral lower first molar in 10-year-olds with normal occlusion during the mixed dentition stage in Tangshan. Methods  Forty-10-year-old students （20 males and 20 females） who had normal occlusion during mixed dentition were selected from an elementary school in Tangshan， China. Once per year for two consecutive years， a dental cast was obtained from each subject， and the cast was scanned with a 3D digital scanner. The three-dimensional measurements of the mandibular dental arch were obtained from the digital model. Results  The lower anterior arch length （LAAL） increased 0.556mm， lower total arch length （LTAL） increased 2.067mm， lower inter primary or permanent canine width （LICW） increased 2.904mm and lower intermolar width （LIMW） increased 2.172mm over the two years. The buccolingual inclination of the lower right first molar （LR6BL） and left first molar （LL6BL） were increased by 2.841° and 5.410°. Conclusion  The lower anterior mandibular arch （LAAL）， the lower total arch length（LTAL）， the lower inter primary or permanent canine width （LICW）， and the lower intermolar width （LIMW） in 10- to 12-year-olds with normal occlusion increased with age. The LIMW were larger in males than in females at 12 years old. The lower bilateral first molar showed buccal inclination with age， but the mesiodistal inclination did not changed significantly. There is no gender difference in the mesiodistal and buccolingual inclination of the lower first molars at 12 years old.

Key words： normal occlusion; lower arch width; lower arch length; lower first molars buccal-lingual inclination; lower first molars mesiodistal inclination; mixed dentition stage; 3D digital model

下前牙在混合牙列阶段的轻度拥挤被认为是一个极为常见的现象。……