Armstrong Conor, Johnston Chris, Burden Donald, Stevenson Mike
Orthodontic Division, Oral Healthcare Research Centre, School of Clinical Dentistry, Queen's University Belfast, UK.
Eur J Orthod. 2003 Dec;25(6):585-9. doi: 10.1093/ejo/25.6.585.
This study compared the use of horizontal parallax (HP) and vertical parallax (VP) radiography for localizing ectopic maxillary canines (EMCs). The true positions of 43 EMCs were determined using the operative notes and subsequent study models following exposure and eruption. Thirty-four palatal and nine buccal EMCs were included in the study. Six experienced orthodontists examined the radiographs of the EMCs and were asked to localize each EMC using VP and HP on separate occasions. The examiners recorded a diagnosis of 'unsure' in 12 per cent of cases using VP and in 5 per cent of cases using HP. The level of agreement of the diagnoses with the true position of the EMCs was significantly greater for HP. Eighty-three per cent of EMCs were correctly located with HP while only 68 per cent were correctly located with VP (P < 0.05). The diagnostic sensitivity for palatally placed canines was significantly greater for HP (88 per cent) than for VP (69 per cent). Both techniques performed poorly when used to localize buccal EMCs, with HP and VP each having a sensitivity of only 63 per cent. It is concluded that HP is superior to VP in diagnostic accuracy, and that two peri-apical radiographs or one peri-apical and one anterior occlusal radiograph are the radiographs of choice for localizing EMCs.
本研究比较了水平视差（HP）和垂直视差（VP）X线摄影术在定位异位上颌尖牙（EMC）中的应用。利用手术记录以及暴露和萌出后的后续研究模型确定了43颗EMC的真实位置。研究纳入了34颗腭侧EMC和9颗颊侧EMC。6名经验丰富的正畸医生检查了EMC的X线片，并被要求分别在不同时间使用VP和HP来定位每颗EMC。检查者在使用VP的病例中12%记录为“不确定”诊断，在使用HP的病例中5%记录为“不确定”诊断。对于HP，诊断结果与EMC真实位置的一致程度显著更高。83%的EMC通过HP能正确定位，而通过VP正确定位的仅为68%（P<0.05）。对于腭侧尖牙，HP的诊断敏感性（88%）显著高于VP（69%）。当用于定位颊侧EMC时，两种技术的表现都很差，HP和VP的敏感性均仅为63%。结论是，HP在诊断准确性方面优于VP，并且两张根尖片或一张根尖片和一张前牙合片是定位EMC的首选X线片。
