Objective

To analyze the prevalence of distal caries in mandibular second molars (M2Ms) and its correlation with the three-dimensional position of mandibular third molars (M3Ms) by cone beam computed tomography (CBCT) images.

Materials and methods

CBCT scans involving 421 M3Ms were assessed. The presence of distal caries of M2Ms, patient age and gender, impaction depths and mesial angulation of M3Ms, the cementoenamel junction (CEJ) distances and contact point localization, and the horizontal positions of M3Ms were assessed. Risk factors were identified by multivariate logistic regression analysis.

Results

The overall prevalence of distal caries in M2Ms was 31.6%. Mesial angulation (16°–75°) of M3Ms, contact point localization at or below the CEJ of M2Ms, and a buccal or lingual position of M3Ms relative to the molar line were identified as risk factors for the prevalence of distal caries in M2Ms (p < 0.05). Distal caries was more severe when the mesial angulation of M3Ms was 16°–75° (p < 0.05).

Conclusions

Buccal or lingual position of M3Ms may represent a new risk factor for the distal caries in M2Ms. Mesial angulation (16°–75°) of M3Ms is a predictive parameter for both the presence and severity of distal caries in M2Ms.

Clinical relevance

As the presence of distal caries in M2Ms is significantly associated with the three-dimensional position of M3Ms, watchful monitoring or prophylactic removal of M3Ms should be deliberated when M3Ms are mesially angulated (16°–75°), buccally or lingually positioned, and with the contact point localization at or below the CEJ of M2Ms.

中文翻译：

---

下颌第三磨牙的三维位置及其与下颌第二磨牙远端龋的关联：锥束计算机断层扫描研究。

目的

通过锥束计算机断层扫描（CBCT）图像分析下颌第二磨牙（M2Ms）中远端龋的患病率及其与下颌第三磨牙（M3Ms）三维位置的相关性。

材料和方法

评估了涉及421个M3M的CBCT扫描。评估M2M的远端龋齿，患者的年龄和性别，M3M的撞击深度和系膜成角，牙釉质交界处（CEJ）距离和接触点定位以及M3M的水平位置。通过多元逻辑回归分析确定危险因素。

结果

M2Ms中远侧龋的总患病率为31.6％。M3Ms的中倾角（16°–75°），M2Ms的CEJ或以下的接触点定位以及M3Ms相对于磨牙线的颊侧或舌侧位置被确定为M2Ms远端龋齿患病率的危险因素（p  ＜0.05）。当M3Ms的近中角为16°–75°时，远端龋齿更为严重（p  <0.05）。

结论

M3Ms的颊侧或舌侧位置可能代表M2Ms远端龋的新危险因素。M3Ms的中间角（16°–75°）是M2Ms远端龋的存在和严重程度的预测参数。

临床相关性

由于M2Ms的远侧龋病与M3Ms的三维位置显着相关，因此，当M3Ms呈近中角（16°-75°），颊侧或舌侧定位以及与M3Ms成角度时，应仔细观察M3Ms的监测或预防性切除。 M2M的CEJ或以下的接触点定位。