Abdul Jabbar Sarah, Nawaia Shaker, Rughwani Vini, Hansen Ken, Naoumova Julia
University Clinic of Orthodontics, Gothenburg, Public Dental Service, Region Västra Götaland, 54130, Sweden.
Specialist clinic of Orthodontics, Skövde Public Dental Service, Region Västra Götaland, 41346, Sweden.
Eur J Orthod. 2025 Jun 12;47(4). doi: 10.1093/ejo/cjaf043.
The congenital absence of mandibular second premolars is a common anomaly requiring careful treatment planning. Conventional extraction of the primary molar often causes spontaneous space closure but may lead to mesial tipping of adjacent teeth. Hemisection offers an alternative to control tooth movement and reduce tipping. However, evidence comparing hemisection and conventional extraction, particularly on space closure and tooth angulation, is limited.
To compare conventional extraction with hemisection of the mandibular primary second molars in terms of space closure, tooth angulation, complications and associated economic implications in patients with congenital absence of mandibular second premolars.
prospective, randomised longitudinal split-mouth.
Patients with bilateral agenesis of the second mandibular molars and unerupted second molars were included and randomly allocated to either extraction or hemisection on the left or right side of the mandible. Clinical and radiographic examinations were conducted at baseline (T1) and after a mean follow-up period of 4.2 years (T2). Measurements of the residual spaces and tooth angulation of the mandibular first molar and premolar following extraction were blinded assessed on panoramic radiographs and cast models. The number of visits, chair time, social costs, and direct and indirect costs were calculated using cost minimisation analysis.
A total of 40 patients (25 boys and 15 girls) with a mean age of 10.03 ± 1.07 years at T1 participated. No patient was lost to follow-up. The residual space between the first permanent molar and the first permanent premolar was 2.04 ± 1.67 mm for hemisection and 2.39 ± 1.86 mm for extraction (p = 0.053). A larger residual space was observed between the first permanent premolar and the canine on the hemisection side (1.80 ± 1.01 mm) than on the extraction side (1.55 ± 0.92 mm), (p = 0.045). No difference was found between the interventions regarding the angulation of the first permanent molar (p = 0.0914) or the angulation of the first permanent premolar (p = 0.7812). Hemisection resulted in significantly more complications (p = 0.0176) and was associated with substantially higher material costs, more chair time and higher indirect costs than conventional extraction (p < 0.0001).
Hemisection is not recommended as an interceptive extraction option for patients with congenitally missing mandibular second premolars, as only minimal, clinically irrelevant differences were observed compared with conventional extraction. Moreover, hemisection is associated with increased costs and a higher risk of complications.
The trial was registered with https://www.researchweb.org/is/sverige, registration number: 967125.
先天性下颌第二前磨牙缺失是一种常见的牙列异常，需要仔细制定治疗计划。常规拔除乳磨牙通常会导致间隙自发关闭，但可能会导致相邻牙齿近中倾斜。半切术是一种控制牙齿移动和减少倾斜的替代方法。然而，比较半切术和常规拔牙术的证据，特别是关于间隙关闭和牙齿角度的证据有限。
比较在下颌第二前磨牙先天性缺失患者中，下颌乳磨牙常规拔牙术与半切术在间隙关闭、牙齿角度、并发症及相关经济影响方面的差异。
前瞻性、随机纵向半口对照试验。
纳入双侧下颌第二乳磨牙未萌出且先天性缺失的患者，并随机分配至下颌左侧或右侧进行拔牙或半切术。在基线时（T1）和平均随访4.2年之后（T2）进行临床和影像学检查。对全景X线片和模型上拔牙后下颌第一磨牙和前磨牙的剩余间隙及牙齿角度进行盲法评估。使用成本最小化分析计算就诊次数、椅旁时间、社会成本以及直接和间接成本。
共有40例患者（25例男性和15例女性）参与，T1时平均年龄为10.03±1.07岁。无患者失访。半切术组第一恒磨牙与第一恒前磨牙之间的剩余间隙为2.04±1.67mm，拔牙术组为2.39±1.86mm（p=0.053）。半切术侧第一恒前磨牙与尖牙之间的剩余间隙（1.80±1.01mm）大于拔牙术侧（1.55±0.92mm），（p=0.045）。两种干预措施在第一恒磨牙的角度（p=0.0914）或第一恒前磨牙的角度（p=0.7812）方面无差异。半切术导致的并发症明显更多（p=0.0176），与常规拔牙术相比，材料成本显著更高、椅旁时间更多且间接成本更高（p<0.0001）。
对于先天性下颌第二前磨牙缺失的患者，不建议将半切术作为预防性拔牙的选择，因为与常规拔牙术相比，仅观察到极小的、临床意义不大的差异。此外，半切术会增加成本和并发症风险。
