Observations on fluid flow from exposed dentine in primary teeth: An in vitro study

ObjectiveTo investigate fluid flow through dentine in primary teeth in vitro using the replica technique, and to compare the results with those obtained from permanent dentine.DesignThe experiments were carried out on 22 extracted, mandibular, primary, incisor teeth. The incisal edge was removed to 1 mm below the dentino-enamel junction and half the exposed surface etched with phosphoric acid. The exposed dentine was blotted dry and the pressure in the pulp cavity held at 0, 15, 30 or 45 cm H₂O above atmospheric for 30 s. Fluid that accumulated on the dentine surface was recorded with impression material and a replica made with epoxy resin which was examined in a scanning electron microscope.ResultsStructures resembling fluid droplets were present in the replicas of unetched dentine in all 22 teeth, and at all the pulpal pressures tested. The droplets formed at 45 cm H₂O were significantly larger (median diam., 5.14 mm; interquartile range, 3.26 mm; Friedman repeated measures analysis of variance on ranks (RMAVR) and Tukey test) than those formed at other pressures. There was no evidence of droplets in the replicas of etched dentine with any of the pulpal pressures.ConclusionsThese results demonstrate that fluid will tend to flow from dentine in deciduous teeth when it is exposed. They are similar to those obtained in a previous study in this laboratory on permanent teeth. The fact that fluid droplets were absent from etched dentine suggests that, after being blotted, the etched dentine matrix absorbed fluid that tended to flow out through the dentinal tubules.     

Sleep duration and remaining teeth among older people

BackgroundNo studies have examined the associations between the numbers of teeth and sleep disturbance. Therefore, we examined the associations between the number of teeth and sleep duration in older people, considering the evidence linking fewer teeth and sleep apnoea through changes in jaw position.MethodsFor this study we used information from a sample of 23,444 cohort participants, randomly selected from the Japan Gerontological Evaluation Study 2010 (N = 169,215). The outcome variable was self-reported sleep duration (h/day), and the explanatory variable was self-reported number of teeth (0, 1–9, 10–19, ≥20). We treated age, sex, body mass index, educational attainment, annual equalized household income, depressive symptoms, physical activity, activities of daily living, presence of diabetes, and smoking status as covariates. Multinomial logistic regression was used among the 20,548 eligible participants with all necessary information.ResultsThe mean age was 73.7 (standard deviation = 6.13) years. Most participants (28.1%) reported sleep duration of 7 h, while a small proportion of the participants reported short (≤4 h, 2.7%) or long (≥10 h, 4.7%) sleep duration. The proportion of edentulous participants was 14.7%. Taking the 7-h sleep duration as the reference category, edentulous participants (relative risk ratio (RRR) = 1.43, 95% confidence interval (CI) = 1.07–1.90) or one to nine teeth (RRR = 1.29, 95% CI = 1.02–1.63) had a significantly higher relative risk ratio for short sleep, independent of covariates. Furthermore, they had a higher relative risk ratio for long sleep duration (RRR = 1.75, 95% CI = 1.40–2.19; RRR = 1.48, 95% CI = 1.21–1.81, respectively).ConclusionsCompared to people with 20 or more teeth, older adults with fewer than 10 teeth have higher risks for short and long sleep durations.     

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??Abstract??Objective To obtain the data of dental measurements in healthy Bai teenagers. Methods Normal dentognathic models were obtained in 97 teenagers. The width of the tooth crown and the size of the dental arch were measured with a venier. The measurments were statistically analysed. Results The tooth crown in boys was wider than that in girls except first premolar and second premolar;the dental arch width and length in boys were wider than those in girls.There was no significant difference in Bolton index and Pont index between boys and girls. Conclusion The norms of teeth??denal arch and dentition index on normal occlusion in Bai teenagers have been established?? and they have a certain reference value to guide clinical orthodontics.     

Evaluation of avulsed primary incisor in 3-year-old girl with hypophosphatasia who received enzyme replacement therapy

Hypophosphatasia (HPP) is an inherited skeletal disease with features of hypomineralization of bone and early exfoliation of primary teeth due to disturbed cementum formation. Recent introduction of enzyme replacement therapy has reduced mortality in severe cases, though the effects of that treatment on dental manifestations remain unknown. We examined an avulsed primary incisor in a 3-year-old female diagnosed with perinatal HPP who underwent enzyme replacement therapy from 1 day after birth and report our findings.     

前牙压低技术在深覆(牙合)患者矫治中的应用进展

深覆(牙合)的治疗是口腔正畸矫治的难点之一.对于伴有垂直生长型、长面型或上唇过短、露龈笑的患者,就更需要医生进行细致诊断,合理选择矫治方法和器械.通过单纯地压低前牙能较为有效地治疗该类患者的深覆(牙合)畸形.目前,临床常用的压低前牙的方法主要有三段式片段弓技术、多用途弓技术、J钩联合高位牵引技术和微种植支抗技术等.本文...     

2×4矫治器配合下后牙面树脂垫治疗乳前牙反的临床研究

目的 探讨2×4矫治器配合下后牙(验)面树脂垫早期阻断矫治乳前牙反(袷)的临床效果.方法 乳牙期前牙反(胎)患者46例,平均年龄(4.2±0.6)岁,采用2×4矫治器配合下后牙(给)面树脂垫高咬合进行早期阻断矫治.配对t检验比较头颅定位侧位片的牙、颌、面测量值在矫治前后的差异.结果 矫治后所有患者乳前牙反(胎)解除.与矫治前相比,上中切牙角(UA-SN)增加11.57° (P ＜0.001),上牙弓长度(is-ms)增加2.26 mm(P＜0.01)；下中切牙角(LA-MP)减小4.38°(P＜0.01),下牙弓长度(ii-mi)减少1.04 mm(P ＜0.01).ANB增大1.44°.结论 2×4矫治器配合下后牙(拾)面树脂垫是早期阻断矫治乳前牙反(殆)的有效方法,患儿易于配合.     

58例年轻恒牙外伤冠折的处理分析

目的：探究年轻恒牙外伤冠折的临床处理方法及效果。方法选择该院2009年3月—2014年9月口腔科门诊就诊年轻恒牙不同程度的外伤冠折的患者58例,依据不同临床表现分别给予直接盖髓术,活髓切断术,根尖诱导术治疗后对患牙进行随诊观察。结果治疗成功患牙52颗,占89%。结论对于年轻恒牙的外伤冠折,选择好正确的治疗方法,大多数患牙能保存牙髓活力,牙根能继续发育,永久性修复后患牙功能良好。     

活动性矫治器早期治疗牙齿反的临床研究

目的：探讨活动性矫治器治疗早期牙齿反的临床疗效,为矫治前牙反提供有效办法。方法对60例牙齿反患儿采用佩戴活动性矫治器的方法进行早期治疗,分别比较这60例患儿治疗前后X线投影测量结果,判断治疗效果。结果60例牙齿反患儿中,矫治时间为2-9个月,其中10例矫治时间2-3个月,37例矫治时间3-7个月,13例矫治时间7-9个月,平均矫治时间（5.8±2.7）个月,所有研究患儿均按照医师要求完成治疗周期;对60例患儿的SNA角、颌凸角、SNB角、ANB角、U1-SN、SN-UIN、CV值治疗前后X线测量显示治疗后较治疗前均显著改善且差异均具有显著的统计学意义（P<0.05）;60例患儿在治疗后结束后1年进行复查,发现有4例儿童复发,均与年龄偏大、存在前牙反的家族史或不良的口腔习惯未破除等原因有密切关系,复发率为6.67%。结论活动性矫治器治疗早期牙齿反具有明显的正畸效果,但同时应该注意对儿童不良习惯的纠正以保持治疗效果。