Karnasuta Piyanuch, Vajrabhaya La-Ongthong, Chongkonsatit Watcharin, Chavanaves Chavalit, Panrenu Nonthana
College of Dental Medicine, Rangsit University, Thailand.
Heliyon. 2020 Jun 30;6(6):e04294. doi: 10.1016/j.heliyon.2020.e04294. eCollection 2020 Jun.
To determine the effect of various horizontal beam angulations on radiographically separating superimposed canals in upper premolars with different external root morphologies.
The independent variables were 1) three different external root morphologies of upper premolars (n = 30); one-root (A), fused-root (B) and two-root (C), 2) thirteen angulations (0° and mesial (Ms) and distal (Ds) shifts of 15, 20, 25, 30, 35, and 40°), and 3) the superimposed canal at the apex (apx) and 5-mm from the apex (5apx). The dependent variables were the percentage of radiographs demonstrating canal separation. The separated canal distances were analysed using analysis of variance (ANOVA) and Tukey HSD.
Separation distances at apx and 5apx on one-root, fused-root and two-root premolar radiographs increased as the angulation increased. Ms angulations generated a higher separation distance (SepDist) in mm compared with the Ds angulations. Significantly different separation distances were observed from various horizontal shift angulations (p < 0.05). Percentage of canal separation from 0 was achieved differently in different morphology of upper premolars (14-80%) at apx and 10-40% at 5apx. The 20-40Ms/Ds and 25Ds/30‒40Ms/Ds resulted in 100% of radiographs with canal separation for two-root and fused-root premolars, respectively, at apx and 5apx. Only the 35/40Ms resulted in 100% of radiographs with separation at apx in one-root teeth.
The ideal horizontal angulation which revealed the superimposed canal at the apx/5apx for one-root, fused-root, and two-root teeth are 35M/35M, 20D/20M, and 15M/20M, respectively.
The 25Ms was the optimal angulation which strongly recommended with the highest probability of separation and acceptable image quality in endodontic and prosthodontic treatment for unknown morphologies evaluated.
确定不同水平投照角度对不同牙根外部形态的上颌前磨牙根管影像重叠分离的影响。
自变量为：1）上颌前磨牙的三种不同牙根外部形态（n = 30）；单根（A）、融合根（B）和双根（C）；2）13种投照角度（0°以及近中（Ms）和远中（Ds）方向分别偏移15°、20°、25°、30°、35°和40°）；3）根尖处（apx）以及根尖上方5毫米处（5apx）的重叠根管。因变量为显示根管分离的X线片的百分比。使用方差分析（ANOVA）和Tukey HSD分析分离的根管距离。
单根、融合根和双根前磨牙X线片在apx和5apx处的分离距离随投照角度增加而增大。与Ds投照角度相比，Ms投照角度产生的分离距离（SepDist）以毫米计更高。不同水平偏移角度的分离距离存在显著差异（p < 0.05）。不同形态的上颌前磨牙在apx处从0开始的根管分离百分比不同（14 - 80%），在5apx处为10 - 40%。20 - 40Ms/Ds以及25Ds/30 - 40Ms/Ds分别使双根和融合根前磨牙在apx和5apx处100%的X线片显示根管分离。仅35/40Ms使单根牙在apx处100%的X线片显示分离。
单根、融合根和双根牙在apx/5apx处显示重叠根管的理想水平投照角度分别为35M/35M、20D/20M和15M/20M。
25Ms是最佳投照角度，在评估未知形态的牙髓病和修复治疗中，强烈推荐该角度，因其分离概率最高且图像质量可接受。
