General Dental Practitioner, Aberdeen, Scotland, UK.
Community Dent Oral Epidemiol. 2010 Feb;38(1):58-67. doi: 10.1111/j.1600-0528.2009.00501.x. Epub 2009 Nov 23.
The appropriateness of extraction of asymptomatic impacted third molars has been much debated and as a result the number of extractions has fallen in the UK in the past few years. As a direct consequence of this decrease more impacted third molars are left in situ and yet, little is known about the natural history of these teeth.
The aim of this study was to create an actuarial life-table and related survival analysis that would shed light on the natural history of an impacted lower third molar.
Panoramic radiographs taken in 14 different general dental practices in Scotland were analysed and matched with their respective case notes in order to generate a sample of patients with asymptomatic impacted lower third molars. Subjects were assessed to confirm the presence of impaction and absence of symptoms and then re-assessed 1 year later for the development of symptoms during the study period to relate the incidence of symptoms within 1 year in the sample studied to age. Logistic regression was used to construct a life table based on the survival of symptom-free teeth (independently of extraction) during the study period.
The number of patients included in the study was 583 and 421 for the baseline and follow-up assessments respectively. The total number of teeth analysed in both appointments was 676; from those 37 (5.47%) were extracted during the study period. About 562 teeth (83.13%) survived the study period symptom-free. There was a statistically significant inverse association between the development of symptoms studied and age. There was no statistically significant association between extraction and age.
The study indicates that older patients are less likely to develop the symptoms studied. In addition the authors believe that there is evidence to suggest that general dental practitioners might not be following current guidelines when deciding whether or not to extract an impacted lower third molar in the centres studied.
无症状阻生第三磨牙的拔除是否合适一直存在争议，因此，过去几年中英国的拔牙数量有所下降。由于这种减少，更多的阻生第三磨牙留在原位，然而，人们对这些牙齿的自然史知之甚少。
本研究的目的是创建一个计算生命表和相关生存分析，以揭示下颌阻生第三磨牙的自然史。
对苏格兰 14 家不同普通牙科诊所拍摄的全景片进行分析，并与相应的病历进行匹配，以生成一组无症状阻生下颌第三磨牙患者的样本。对受试者进行评估以确认存在阻生和无症状，然后在研究期间 1 年后重新评估是否出现症状，以将研究样本中 1 年内出现症状的发生率与年龄相关联。使用逻辑回归构建基于研究期间无症状牙齿（独立于拔牙）生存的生命表。
研究共纳入 583 名患者进行基线评估，421 名患者进行随访评估。两次就诊时共分析了 676 颗牙齿；其中 37 颗（5.47%）在研究期间被拔除。约 562 颗牙齿（83.13%）在研究期间无症状存活。研究中出现症状与年龄之间存在统计学上显著的负相关。拔牙与年龄之间没有统计学上的显著关联。
该研究表明，年龄较大的患者出现研究中症状的可能性较小。此外，作者认为有证据表明，在研究中心，普通牙科医生在决定是否拔除下颌阻生第三磨牙时可能没有遵循当前的指南。
