Change in contacts with age

Background: Although a series of studies on OXIS contacts have been performed, studies regarding changes in OXIS contacts over time are lacking. Therefore, this study aimed to evaluate the change in contact type between primary molars after 3 years in children aged 3–7 years.
Methods: This longitudinal study was conducted using 2922 sectional die models of 926 children. At baseline (T0), the contact type between the primary molars was scored using replication via the sectional die model method according to the OXIS criteria. After 3 years, the sectional die models of the same children were scored using the same criteria (T1).
Results: McNemar’s tests revealed a significant change in contacts from baseline to 3 years. The post hoc test explained specific changes in the contacts that were observed to be significant. These were O to X (p<0.001), O to I (p<0.001), O to S (p=0.035), and I to X (p<0.001).
Conclusions: A significant change in OXIS contact over time was observed. The O-type contact underwent the maximum change.
Practical implications: Interproximal contacts change with time in growing children. The least and most stable contacts are the “O” and “I” types, respectively. This change in contact type with age may alter the risk of caries in children.

背景：尽管已有多项针对OXIS接触（OXIS contacts）的研究，但有关OXIS接触随时间变化的相关研究仍较为匮乏。因此，本研究旨在评估3~7岁儿童的乳牙磨牙间接触类型在3年后的变化情况。
方法：本项纵向研究纳入了926名儿童的2922个分段代型模型（sectional die models）。基线期（T0）时，采用分段代型模型复制法，依据OXIS标准（OXIS criteria）对乳牙磨牙间的接触类型进行评分。3年后，对同一批儿童的分段代型模型采用相同标准再次进行评分（T1）。
结果：麦克内马尔检验（McNemar’s tests）显示，从基线期至3年后，接触类型发生了显著变化。事后检验（post hoc test）明确了部分具有统计学意义的特定接触类型转化，具体包括O型向X型转化（p<0.001）、O型向I型转化（p<0.001）、O型向S型转化（p=0.035）以及I型向X型转化（p<0.001）。
结论：本研究发现OXIS接触类型随时间推移发生了显著变化，其中O型接触的变化幅度最大。
实践意义：处于生长发育期的儿童，其牙间接触类型会随时间发生改变。其中稳定性最差与最佳的接触类型分别为O型与I型。这种随年龄增长出现的接触类型变化，可能会改变儿童罹患龋病的风险。