Lin Yng-Tzer J, Lin Yai-Tin
Pediatric Dentistry, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan, ROC.
J Dent Sci. 2017 Mar;12(1):44-48. doi: 10.1016/j.jds.2016.06.005. Epub 2016 Aug 9.
BACKGROUND/PURPOSE: The consequence of premature loss of primary teeth resulting in the need for space maintainers has been controversial for many years. There is no longitudinal long-term report in literature regarding the premature loss of a primary maxillary first molar. The aim of this study was to continue observing the long-term space changes of 19 cases following premature loss of a primary maxillary first molar during the transition from primary to permanent dentition.
Ten of the 19 original participants were excluded because of extensive decay or loss to follow-up. Nine children (mean age at time of tooth extraction, 6.0 ± 0.42 years) with unilateral premature loss of a primary maxillary first molar were examined. Maxillary dental study casts were obtained 2 days or 3 days after tooth removal and, on average, 81 months later. The contralateral intact primary molars in each participant served as controls. The arch width, arch length, intercanine width, intercanine length, and arch perimeter of each study cast from the initial and follow-up examinations were measured and compared using paired -tests.
Eight of nine cases (88.9%) did not show crowded permanent successors or canine block-out at the extraction site. Interestingly, the permanent dentition was more crowded at the control site (2/9) than at the extraction site (1/9). The arch width, arch length, intercanine width, and intercanine length significantly increased at 81 months (P < 0.05), whereas the arch perimeter increases approached significance (P = 0.071).
The anterior and posterior arch dimensions significantly increased 81 months after premature loss of a primary maxillary first molar, which suggested that space maintainers were not needed in these cases.
背景/目的：多年来，乳牙过早脱落导致需要使用间隙保持器的后果一直存在争议。文献中没有关于上颌第一乳磨牙过早脱落的纵向长期报告。本研究的目的是继续观察19例上颌第一乳磨牙过早脱落在从乳牙列向恒牙列过渡期间的长期间隙变化。
19名原始参与者中有10名因广泛龋坏或失访而被排除。对9名单侧上颌第一乳磨牙过早脱落的儿童（拔牙时平均年龄为6.0±0.42岁）进行了检查。在拔牙后2天或3天以及平均81个月后获取上颌牙齿研究模型。每个参与者的对侧完整乳牙用作对照。对每次初始检查和随访检查的每个研究模型的牙弓宽度、牙弓长度、尖牙间宽度、尖牙间长度和牙弓周长进行测量，并使用配对t检验进行比较。
9例中有8例（88.9%）在拔牙部位未出现恒牙拥挤或尖牙阻萌。有趣的是，恒牙列在对照部位（2/9）比在拔牙部位（1/9）更拥挤。81个月时，牙弓宽度、牙弓长度、尖牙间宽度和尖牙间长度显著增加（P<0.05），而牙弓周长增加接近显著水平（P=0.071）。
上颌第一乳磨牙过早脱落后81个月，前后牙弓尺寸显著增加，这表明在这些情况下不需要间隙保持器。
