Department of Orthodontics, Tangshan Union Medical College Hospital, Tangshan 063000, Hebei, China.
Department of Stomatology, Tangshan Voccational & Technical College, Tangshan 063000, Hebei, China.
J Healthc Eng. 2021 Jun 3;2021:8872022. doi: 10.1155/2021/8872022. eCollection 2021.
The purpose of this study was to observe the dental arch asymmetry in 12-year-olds with normal occlusion during the early permanent dentition stage.
Ninety-two 12-year-old students (46 males and 46 females) who had normal occlusion during early permanent dentition were selected from a junior high school in Tangshan, China. Once per year for three consecutive years, a dental cast was obtained from each subject, and the cast was scanned with a 3D digital scanner (R700 3D). The median palatal plane (MPP) and transverse palatal plane (TPP) were used as the reference plane for the transverse and anteroposterior measurements, respectively.
Most of the dental arch asymmetry indicators decreased with age, but these differences were not statistically significant. The values of the midincisal edge of the upper central incisors (U1), midincisal edge of the upper lateral incisors (U2), upper canine cusp tip (U3), upper first premolar buccal cusp tip (U4), upper second premolar buccal cusp tip (U5), upper first molar mesiobuccal cusp tip (U6MB), and upper first molar distobuccal cusp tip (U6DB) to the TPP were 0.019 mm, 0.279 mm, 0.017 mm, 0.016 mm, 0.016 mm, 0.027 mm, and 0.200 mm, respectively; these values were larger in males than in females ( < 0.05). The values of 2-5, 6MB, and 6DB-TPP were 0.154 mm, 0.102 mm, 0.119 mm, 0.259 mm, 0.206 mm, and 0.123 mm, respectively, larger in the mandibular than in the maxillary dental arch ( < 0.05). The values of the midincisal edge of the lower central incisors (L1), midincisal edge of the lower lateral incisors (L2), lower canine cusp tip (L3), lower first premolar buccal cusp tip (L4), lower second premolar buccal cusp tip (L5), lower first molar mesiobuccal cusp tip (L6MB), and lower first molar distobuccal cusp tip (L6DB) to the MPP were 0.399 mm, 0.197 mm, 0.258 mm, 0.248 mm, 0.214 mm, 0.575 mm, and 0.531 mm, respectively, larger than L1-5, L6MB, and L6DB-TPP ( < 0.05).
The asymmetry of the dental arch in 12-to-15-year-olds with normal occlusion did not change significantly with age. The anteroposterior asymmetry of the maxillary dental arch is larger in males than in females. With the exception of the central incisor, the anteroposterior asymmetry of the mandibular dental arch is larger than that of the maxillary dental arch. The transverse asymmetry of the mandibular dental arch is larger than the anteroposterior asymmetry.
本研究旨在观察恒牙早期正常合 12 岁儿童的牙弓对称性。
从中国唐山市一所初中选取 92 名恒牙早期正常合的 12 岁学生（男 46 名，女 46 名）。连续 3 年，每年从每位受试者中获取一副牙模，并用 3D 数字扫描仪（R700 3D）对牙模进行扫描。正中腭平面（MPP）和横腭平面（TPP）分别作为横向和前后测量的参考平面。
大多数牙弓不对称指标随年龄增长而减小，但差异无统计学意义。上中切牙切缘中点（U1）、上侧切牙切缘中点（U2）、上尖牙牙尖顶点（U3）、上第一前磨牙颊尖顶点（U4）、上第二前磨牙颊尖顶点（U5）、上第一磨牙近中颊尖顶点（U6MB）和上第一磨牙远中颊尖顶点（U6DB）到 TPP 的值分别为 0.019mm、0.279mm、0.017mm、0.016mm、0.016mm、0.027mm和 0.200mm，男性均大于女性（<0.05）。2-5、6MB 和 6DB-TPP 的值分别为 0.154mm、0.102mm、0.119mm、0.259mm、0.206mm和 0.123mm，下颌牙弓均大于上颌牙弓（<0.05）。下中切牙切缘中点（L1）、下侧切牙切缘中点（L2）、下尖牙牙尖顶点（L3）、下第一前磨牙颊尖顶点（L4）、下第二前磨牙颊尖顶点（L5）、下第一磨牙近中颊尖顶点（L6MB）和下第一磨牙远中颊尖顶点（L6DB）到 MPP 的值分别为 0.399mm、0.197mm、0.258mm、0.248mm、0.214mm、0.575mm和 0.531mm，均大于 L1-5、L6MB 和 L6DB-TPP（<0.05）。
恒牙早期正常合 12-15 岁儿童牙弓的不对称性随年龄变化无明显变化。上颌牙弓的前后向不对称性男性大于女性。除中切牙外，下颌牙弓的前后向不对称性大于上颌牙弓。下颌牙弓的横向不对称性大于前后向不对称性。
