Department of Dentoalveolar Surgery, Implant Surgery and Radiology, School of Dentistry, Aristotle University of Thessaloniki, Greece.
Int J Gen Med. 2013 Sep 16;6:747-55. doi: 10.2147/IJGM.S42929. eCollection 2013.
The study reported here investigated the first radiographic evidence of third molar (M3) formation, their incidence and distribution as well as their congenital absence on the right or the left side in either the maxilla or the mandible, in both male and female Greek orthodontic patients.
A total of 618 panoramic radiographs were initially examined. After the application of inclusion/exclusion criteria, the group finally selected consisted of 428 patients (mean age 11.64 years, range 5-18): 179 males (mean age 11.73 ± 2.46) and 249 females (mean age 11.57 ± 2.45). The collected data were analyzed using SPSS software (IBM, Armonk, New York, NY, USA). The level of significance for all analyses was set to p = 0.05. The chi-square (χ(2)) test was used to assess the relationships between variables. The Wilcoxon's signed-rank test and the Mann-Whitney U test were also used for comparisons as well as the Spearman's rho test for correlations.
M3s were first detected in females at the age of 7 years whereas males followed one year later at the age of 8 years. A strong correlation between age and M3 development was revealed for both sexes (Spearman's rho = 0.177, p = 0.05). Presence of all four M3s was the most common incidence (present in 70.8% of study subjects), followed by the agenesis of two (12.1%), agenesis of all four (8.4%), one (6.8%), and three (1.9%) M3s. Congenitally missing M3s in all subjects showed a significantly greater predilection for the maxilla over the mandible (19.6% and 15.5%, respectively) (Wilcoxon signed-rank test Z = -2.404, p = 0.016). However, the distribution was found equal between the two sides of the jaws. The difference between the absent frequencies of M3s in the mandible and the maxilla was found statistically significant for the total sample (McNemar's test, p < 0.001) and for males (p = 0.041) as well.
The study data may provide a reference for the M3 genesis in Greeks.
本研究旨在报告首例第三磨牙（M3）形成的影像学证据，以及其在希腊正畸患者中上颌或下颌的左右侧、男女双侧的萌出、发生率和分布情况，以及先天缺失情况。
共检查了 618 张全景片。应用纳入/排除标准后，最终选择了 428 名患者（平均年龄 11.64 岁，范围 5-18 岁）：男性 179 名（平均年龄 11.73 ± 2.46），女性 249 名（平均年龄 11.57 ± 2.45）。使用 SPSS 软件（IBM，Armonk，New York，NY，USA）对收集的数据进行分析。所有分析的显著性水平均设为 p = 0.05。采用卡方（χ(2)）检验评估变量之间的关系。还使用 Wilcoxon 符号秩检验和 Mann-Whitney U 检验进行比较，以及 Spearman 秩相关系数检验进行相关性分析。
女性 M3 最早在 7 岁时被首次发现，而男性则在 1 年后的 8 岁时出现。结果显示，无论男女，年龄与 M3 发育之间均存在很强的相关性（Spearman 秩相关系数=0.177，p = 0.05）。4 颗 M3 均存在的发生率最高（研究对象中有 70.8%存在），其次是 2 颗缺失（12.1%）、4 颗缺失（8.4%）、1 颗缺失（6.8%）和 3 颗缺失（1.9%）。所有受试者中先天缺失的 M3 明显更倾向于上颌（19.6%和 15.5%）（Wilcoxon 符号秩检验 Z = -2.404，p = 0.016）。然而，在颌骨的左右两侧分布均等。下颌 M3 缺失频率与上颌 M3 缺失频率的差异在总样本中具有统计学意义（McNemar 检验，p < 0.001），在男性中也具有统计学意义（p = 0.041）。
本研究数据可为希腊人 M3 发育提供参考。
