An Jin-Kyu, Matsumoto Yoshiro, Ono Takashi
Department of Orthodontic Science, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
Korean J Orthod. 2017 Nov;47(6):365-374. doi: 10.4041/kjod.2017.47.6.365. Epub 2017 Sep 29.
The objective of this study is to investigate the eruption pattern and root resorption of the bovine anterior dentition in relation to growth-related parameters based on dental maturity.
A cross-sectional study was conducted on 110 bovine anterior mandibles by using standard radiography, cone-beam computed tomography (CBCT), and actual measurements. We determined the relationships between the stages of dental maturity by using a modification of Demirjian's method and various growth-related parameters, such as the activity of the root-resorbing tissue and mobility of the deciduous teeth. The correlation of growth-related parameters with interdental spacing and distal unusual root resorption (DRR) of the deciduous fourth incisor was assessed. The cause of mesial unusual root resorption (MRR) of the deciduous fourth incisor was determined on the basis of the arrangement of the permanent third incisor.
An independent -test and chi-square test indicated significant differences in growth-related parameters associated with dental arch length discrepancy and factors related to the shedding of deciduous teeth between the low and high dental maturity groups. The samples with interdental spacing and DRR showed a larger sum of mesiodistal permanent crown widths and higher dental maturity than did the respective controls. Samples with MRR tended to show a lingually rotated distal tip of the adjacent tooth crown.
Dental maturity has relevance to the interdental spaces and unusual root resorption of mixed dentition. The position of the adjacent tooth crown on CBCT may be correlated with the occurrence of unusual root resorption of the incisor.
本研究的目的是基于牙齿成熟度,研究牛前牙列的萌出模式和牙根吸收与生长相关参数的关系。
采用标准X线摄影、锥形束计算机断层扫描(CBCT)和实际测量对110个牛下颌前部进行横断面研究。我们通过改良的德米尔坚方法确定牙齿成熟阶段与各种生长相关参数之间的关系,如牙根吸收组织的活性和乳牙的松动度。评估生长相关参数与乳牙第四切牙的牙间隙和远中异常牙根吸收(DRR)的相关性。根据恒牙第三切牙的排列确定乳牙第四切牙近中异常牙根吸收(MRR)的原因。
独立样本t检验和卡方检验表明,在低牙齿成熟度组和高牙齿成熟度组之间,与牙弓长度差异相关的生长相关参数以及与乳牙脱落相关的因素存在显著差异。与各自的对照组相比,有牙间隙和DRR的样本显示近远中恒牙冠宽度总和更大,牙齿成熟度更高。有MRR的样本倾向于显示相邻牙冠的远中端向舌侧旋转。
牙齿成熟度与混合牙列的牙间隙和异常牙根吸收有关。CBCT上相邻牙冠的位置可能与切牙异常牙根吸收的发生有关。