Development of a stain shade guide to aid the measurement of extrinsic dental stain

Abstract:  Background:  Accurate and reproducible assessment of extrinsic staining is pivotal to determining efficacy of some tooth whitening oral hygiene products. The aim of this study was: (1) to produce a stain shade guide to aid the in vitro and in vivo stain assessment (2) to assess intra- and inter-examiner reproducibility of stain assessment using the stain shade guide. Method:  Using chlorhexidine and tea, perspex and acrylic teeth specimens were stained. The amount of staining on the perspex was measured with a spectrophotometer and the values obtained were assigned to the stained acrylic teeth, which were made into a stain guide. Using clinical photographs and a group of 10 volunteers, stain area and intensity were assessed using the stain guide and the recognized Lobene stain index by two examiners. The degree of intra- and inter-examiner reproducibility for these measurements were assessed using Cohen's kappa statistics. Results:  For both the clinical examination and use of photographs, intra-examiner reproducibility for stain intensity was improved when using the stain guide compared with the Lobene Index. Similarly, when assessing inter-examiner reproducibility, stain intensity kappa values were greater using the stain guide ( κ  = 0.82) compared with the Lobene Index ( κ  = 0.57). Conclusion:  The findings of this study would suggest that the use of the stain guide could be of importance in the assessment of extrinsic dental stain.     

比色板与电脑比色仪比色准确性的分析

目的 通过分析比色板与电脑比色仪比色的准确性,探讨电脑比色仪对比色板色标未能覆盖颜色的精确表达作用.方法 选取天然牙颜色分布相对均一的单颗前牙全瓷冠修复患者120例,按照随机数字表分为两组(V组和S组),每组60例.V组采用比色板,S组采用电脑比色仪,对患者的天然牙进行比色;再根据测色结果分为色标颜色组(V1、S1)和中间颜色组(V2、S2).修复后使用电脑比色仪对所有修复体及V组比色参照的天然牙进行测色,分别计算每组修复体中部与天然牙中部的总色差△E*ab,对结果进行配对t检验.结果 V组△E*ab(3.92±1.59)与S组△E*ab(2.23±0.96)的差异有统计学意义(P＜0.01);V1组△E*ab(2.29±0.88)与V2组△E*ab(4.42±1.42)的差异有统计学意义(P＜0.01);S1组△E*ab(2.12±0.84)与S2组△E*ab(2.27±1.01)的差异无统计意义(P=0.014).V2组AE*ab与S2组△E*ab的差异有统计学意义(P＜0.01);V1组△E*ab与S1组△E*ab的差异无统计学意义(P=0.698).结论 对于比色板色标未能覆盖的颜色,电脑比色仪的定位与表达比单纯用比色板比色更准确,利于指导修复体的颜色再现.     

Spectrophotometric Determination of Irrigant Extrusion Using Passive Ultrasonic Irrigation,EndoActivator, or Syringe Irrigation

Introduction

Sodium hypochlorite (NaOCl) irrigation is critical to endodontic success, and several new methods have been developed to improve irrigation efficacy (eg, passive ultrasonic irrigation [PUI] and EndoActivator [EA]). Using a novel spectrophotometric method, this study evaluated NaOCl irrigant extrusion during canal irrigation.

Methods

One hundred fourteen single-rooted extracted teeth were decoronated to leave 15 mm of the root length for each tooth. Cleaning and shaping of the teeth were completed using standardized hand and rotary instrumentation to an apical file size #40/0.04 taper. Roots were sealed (not apex), and 54 straight roots (n = 18/group) and 60 curved roots (>20° curvature, n = 20/group) were included. Teeth were irrigated with 5.25% NaOCl by 1 of 3 methods: passive irrigation with needle, PUI, or EA irrigation. Extrusion of NaOCl was evaluated using a pH indicator and a spectrophotometer. Standard curves were prepared with known amounts of irrigant to quantify amounts in unknown samples.

Results

Irrigant extrusion was minimal with all methods, with most teeth showing no NaOCl extrusion in straight or curved roots. Minor NaOCl extrusion (1–3 μL) in straight roots or curved roots occurred in 10%–11% of teeth in all 3 irrigant methods. Two teeth in both the syringe irrigation and the EA group extruded 3–10 μL of NaOCl.

Conclusions

The spectrophotometric method used in this study proved to be very sensitive while providing quantification of the irrigant levels extruded. Using the PUI or EA tip to within 1 mm of the working length appears to be fairly safe, but apical anatomy can vary in teeth to allow extrusion of irrigant.     

居住区大气中铍的桑色素荧光分光光度法检验方法的改良

[目的]对居住区大气中铍的卫生检验标准方法-桑色素荧光分光光度法进行优化改良。[方法]按照国家环境污染物监测方法标准制修订技术导则,对我国现行的居住区大气中铍的卫生检验标准方法-桑色素荧光分光光度法进行了优化改良,并对改良后的方法进行方法学评价。[结果]方法的检出限为0.05ng/ml,测定下限为0.2ng/ml,测量范围为0.0002～0.005μg/ml,对空气中铍的测定范围为0.002～0.05μg/m3(采样体积为1m3)。相对标准偏差分别为2.5%～4.2%(n=6)。回收率为98.0～106.0%。[结论]改良后的方法比原标准方法更加简便易操作,提高了方法灵敏度、测定的精密度和准确度。     

母鼠注射麻黄素对仔鼠肝组织结构和总抗氧化能力、谷胱甘肽转移酶活性及丙二醛含量的影响

目的:探讨妊娠或哺乳期女性食用麻黄素对胎幼儿的影响。方法:给妊娠和哺乳期母鼠连续腹腔注射不同剂量(2、4、6 g/L)的麻黄素溶液,用分光光度法检测仔鼠肝组织总抗氧化能力(T-AOC)、谷胱甘肽转移酶(GST)活性及丙二醛(MDA)含量的变化,生物显微技术观察仔鼠肝组织结构的变化。结果:麻黄素组仔鼠肝组织结构出现不同程度的病理性变化,肝血窦扩张,并有内皮细胞脱落、肝板萎缩等现象,仔鼠肝组织T-AOC、GST活性降低,肝组织MDA含量升高,与对照组比较差异有统计学意义。结论:母鼠注射麻黄素会影响仔鼠肝组织结构和功能,麻黄素及其代谢物可能经胎盘或乳汁进入仔鼠体内损伤仔鼠肝组织的抗氧化系统,机体脂质过氧化反应增强,影响细胞的能量代谢。     

简化血样中微量铜测定方法的探讨

目的寻求一种使用简单、成本低廉且快速准确的血样中微量铜的检测方法。方法利用Cu^2＋对H2O2与氢醌反应起催化作用的原理,选择了在弱碱性的NH3-NH4F介质中,该催化体系的优化条件,建立了催化分光光度法测定血样中铜含量的方法。结果方法检出限为6×10^-10g／mL,加标回收率在98％～102％之间,变异系数在1．5-4,6之间。结论该方法是测定血样中微量铜的简单、可靠、分析时间短、灵敏度高、抗干扰能力强的分析方法。     

过硫酸铵消化-砷铈催化分光光度法结合控温油浴测定尿碘的结果观察

目的观察尿样经控温油浴消化后尿碘结果的精确度和准确度。方法控温油浴代替电热消解仪消解尿样,采用"尿中碘的砷铈催化分光光度测定方法"(WS/T107-2006)测定尿碘。结果标准曲线线性范围为0～300μg/L,相关系数平均为-0.9998。精确度:测定尿碘为(67.6±10)、(110.5±10)、(223.4±10)μg/L的3份尿样,变异系数分别为3.1%、2.3%、4.7%(n=6)。准确度:测定碘含量为(78.4±9)、(150.5±10)μg/L的2份尿碘国家标准物质,相对标准偏差分别为4.8%和2.8%(n=6)。结论控温油浴可以取代电热消解仪消解尿样进行尿碘测定,具有控温精准,制作容易的优点。     

薄壁滤过泡对青光眼患者泪液中抗坏血酸浓度的影响

目的 探讨青光眼患者薄壁滤过泡的存在对患眼泪液成分的影响。设计 横断面研究。 研究对象 选择距抗青光眼滤过术后至少6个月的薄壁滤过泡患者10例、厚壁滤过泡患者11例和无滤过泡者15例。方法 利用紫外分光光度计测量以上三组患者泪液中抗坏血酸的含量。主要指标 泪液中抗坏血酸浓度。 结果 薄壁滤过泡组、厚壁滤过泡组和无滤过泡组泪液中抗坏血酸含量分别为（713.53±132.32）μg/ml,（502.52±93.90）μg/ml和（470.95±86.85）μg/ml,三组间存在统计学差异（F=18.117,P=0.000）,薄壁滤过泡组抗坏血酸浓度显著高于无滤过泡组和厚壁滤过泡组（P=0.000, P=0.000）,而厚壁滤过泡组与无滤过泡组间无显著差异（P=0.446）。结论 青光眼患病术后薄壁滤过泡中的房水可经由菲薄的结膜组织渗出至眼表,改变患眼的泪液组成。（眼科,2013, 22： 339-343）