The apically repositioned flap in tooth exposure

Methods of exposing impacted teeth in order to bring them into the line of the arch include gingivectomy, the apically repositioned flap and closed eruption techniques. These procedures aim to facilitate the eruption of the impacted tooth with a minimum of disruption or damage to the tooth itself or adjacent structures. The aim of this paper is to discuss the various surgical methods of exposing impacted teeth and to help to identify where the use of the apically repositioned flap is indicated. Clinical examples are presented and a surgical method for carrying out this procedure recommended.     

牙齿重度磨耗露髓45例误诊分析

目的:减少牙齿重度磨耗露髓在口腔科的误诊误治。方法:收集最终确诊为重度磨耗露髓的患者资料45例,年龄61-78岁,调查其初诊诊断情况。确诊方法:患者重度磨耗之牙本质中央,可见针尖大穿髓孔,探针探诊无探痛,用8号扩大针可自穿髓处刺入,诱发剧烈疼痛。结果:初诊诊断:12例无阳性症状无法诊断,建议继续观察;18例诊断为牙本质过敏,给以脱敏治疗;3例怀疑根裂,建议拔除牙齿;6例怀疑三叉神经痛,建议到神经内科诊治;6例诊断为邻牙病变。结论:重度磨耗露髓的患牙,可能不伴有自发痛,容易被误诊误治。在露髓孔极小的情况下,可使用8号扩大针代替临床常用的一次性探针,能减少因一次性探针相对过粗无法探入露髓孔导致的漏诊误诊。     

Assessing the association between bisphosphonate exposure and delayed mucosal healing after tooth extraction

BackgroundTooth extraction in patients exposed to bisphosphonates (BPs) is considered a risk factor for osteonecrosis. The authors evaluated the time to mucosal healing and frequency of osteonecrosis after tooth extraction in participants exposed to BPs.MethodsThe authors compared wound healing after tooth extraction in participants exposed to BPs with that in control participants who had not been exposed to BPs. Variables included age, sex, type of BP therapy (oral or intravenous), BP exposure time and C-terminal telopeptide (CTX) test results. The authors followed up patients weekly or biweekly until healing was complete. They used multivariable analyses to model time to healing in the presence of covariates, and estimates provided hazard ratios (HRs) and 95 percent confidence intervals (CIs) adjusted for all variables in the model.ResultsThe authors enrolled 53 participants with BP exposure and 39 control participants. Postextraction healing was significantly longer in participants exposed to BPs (P < .001) than it was in control participants. One patient (1.9 percent) developed osteonecrosis. A Cox proportional hazards model in which the authors controlled for age, sex and CTX values showed that BP exposure alone significantly (adjusted HR, 0.27; 95 percent confidence interval, 0.16–0.48) increased mucosal healing time.ConclusionsThe study results showed that postextraction healing was impaired in patients exposed to BPs. CTX values were not associated with delayed healing after tooth extraction.Practical ImplicationsPostextraction healing was delayed in patients receiving BP therapy. However, the risk of developing osteonecrosis was low.     

孕期健康和环境暴露对牙发育的影响

牙发育是复杂信号网络调控的牙源性上皮和神经嵴来源牙源性间充质之间交互作用的结果,遗传因素及环境因素在此过程中均发挥重要作用。母体是胎儿生长发育的主要载体,孕期母体健康和环境暴露对胎儿和儿童牙发育具有较大影响。本文根据不同类型的孕期母体环境因素,重点从环境内分泌干扰物、多种化学物质的联合作用及母体健康等三个方面对胎儿和儿童牙发育的关键问题进行综述,探讨了孕期环境因素在釉质发育缺陷、磨牙切牙矿化不全、氟牙症、多生牙及先天性缺牙等牙发育异常中的作用,为从生命早期预防牙发育异常、评估牙发育异常风险、进行牙发育相关咨询、促进儿童口腔健康管理提供理论依据。     

Dentin exposure in tooth preparations for porcelain veneers: a pilot study

STATEMENT OF PROBLEM: The various clinical techniques available for even reduction of a tooth surface to receive a porcelain veneer restoration do not produce a consistently even conservative reduction. In addition, it is not known which technique is most conservative of enamel. PURPOSE: The purpose of this pilot study was to assess the effectiveness of 3 clinical techniques, namely, dimple, depth groove, and freehand, in producing an intraenamel preparation. The relation between overpreparation beyond the commonly accepted depth of preparation of 0.5 mm and dentin exposure was also examined. MATERIAL AND METHODS: A single operator prepared 3 groups of 5 extracted maxillary central incisors to a depth of 0.5 mm using dimple, depth-groove, and freehand methods of tooth preparation. The prepared teeth were scanned using an x-ray microtomography scanner. The reconstructed images were studied using software that provided a volume-rendering routine so that, by choosing suitable x-ray linear attenuation coefficient thresholds, enamel (2.78 cm(-1) at 40 keV) and dentin (1.63 cm(-1) at 40 keV) surfaces could be viewed. The percentage area of enamel conserved was analyzed from these images. Coordinate metrology was used to produce color-coded images depicting the depth of preparation. The Kruskal-Wallis test was used to determine the statistical significance (alpha=.05) in the difference between the mean percentage area of enamel conserved in the 3 technique groups. The coordinate metrology and x-ray microtomography images were visually compared to study the correlation between overpreparation and dentin exposure. RESULTS: The Kruskal-Wallis test did not demonstrate significant difference (P=.07) between the 3 techniques in conserving enamel. However, the dimple technique showed a greater trend to retaining a larger mean percentage area of enamel (77.5% +/- 14.2) compared to depth-groove (50.1% +/- 17.5) and freehand (76.8% +/- 24.4) techniques. Preparation depth in the range of 0.4 to 0.6 mm was largely seen to be intraenamel, except in the cervical region. CONCLUSION: Within the limitations of this pilot study, the 3 different techniques tested did not differ significantly in conserving enamel.     

2,3,7,8-四氯二苯并二恶英哺乳期暴露对仔鼠牙齿的显微硬度分析

目的探讨哺乳期二恶英类物质2,3,7,8-四氯二苯并二恶英(2,3,7,8-tetrachlorodibenzo-p-dioxin,2,3,7,8-TCDD)暴露对大鼠釉质和牙本质显微硬度的影响。方法应用给予低浓度2,3,7,8-TCDD染毒方法,建立哺乳期2,3,7,8-TCDD暴露模型,收集日龄60 d大鼠牙齿作为实验样品。2,3,7,8-TCDD暴露组和对照组大鼠下颌切牙沿牙长轴切割,抛光后在不同选择区域行维氏显微硬度的测定。结果同对照组相比,2,3,7,8-TCDD暴露组压痕较深。釉质平均显微硬度比较,2,3,7,8-TCDD暴露组明显降低,两组差异有显著性(P<0.01)。牙本质平均显微硬度比较,2,3,7,8-TCDD组较低,两组有统计学意义(P<0.01)。结论 2,3,7,8-TCDD暴露对牙齿硬组织质量有影响,牙齿的机械抗力降低。     

The fluoride content of human tooth enamel in relation to environmental exposure to fluoride

A bstract — Double-layer superimposed biopsies were used for sampling sound labial enamel of upper permanent central incisor teeth of 189 children (mean age 8.4 years, SD = 0.36), comprising five groups, representing life-long exposure to contrasting concentrations of F in the water (range ≤0.12 ppm to 2.8 ppm) and to supplements of 200 or 350 mg F/kg domestic salt. The mean F concentrations of enamel ranged through the groups from 924 ppm to 2401 ppm in the surface layer (average central depth = 0.49 um) and from 450 ppm to 1428 ppm in the subsurface layer (average central depth = 2.62 um). The differences between the mean F concentrations of the groups were significant in each instance and the values consistently reflected the extent of F exposure. It was concluded that the F content of enamel is a reliable indicator of environmental exposure to F for populations, but not for every individual.     

Problems in exposure assessment of fluoride in drinking water

OBJECTIVES: We developed a source documentation approach that identified fluoride content of drinking water at the state or local level to estimate fluoride concentrations from public water systems. We then compared estimates from this approach with estimates obtained from a single source, the 1992 Centers for Disease Control and Prevention (CDC) Fluoridation Census. METHODS: We used residential histories from a case-control study. For each residence we attempted to determine fluoride concentrations using the 1992 CDC Fluoridation Census. For the source documentation method we utilized multiple sources from state and local contacts to verify and collect additional data. We compared the fluoride estimates obtained by the two methods. RESULTS: When fluoride values were found using both methods, there was good correlation (Kendall's tau = 0.85; 95% confidence interval = 0.79, 0.90) and concordance was 96 percent. We obtained over 99 percent of the fluoride values needed using source documentation as compared to 49 percent of the values needed when we used a single publication. When fluoride values were missing using the 1992 CDC Fluoridation Census, 21 percent had source documentation estimates of at least 0.7 ppm. CONCLUSIONS: Researchers need to consider limitations of using a secondary data source to estimate fluoride in drinking water, particularly in studies where exposure to fluoride is the primary exposure of interest.     

哺乳期2,3,7,8-TCDD暴露仔鼠牙齿的组织计量学观测

目的：研究哺乳期2,3,7,8-TCDD暴露对大鼠牙齿的组织形态计量学的影响。方法：30d和60d龄2,3,7,8-TCDD暴露组和对照组大鼠被处死,将其带有磨牙的上颌骨行树脂包埋,制备硬组织磨片并在荧光显微镜下观察。对两实验组牙齿的组织形态、荧光标记情况及组织形态计量学参数进行比较。结果：2,3,7,8-TCDD组釉质和牙本质均相对薄弱。牙齿形态计量学参数比较,2,3,7,8-TCDD组与对照组间均显示显著性差异。牙本质计量学比较,2,3,7,8-TCDD组参数均有降低（G-Ir.L.Wi：12.58±1.54,12.58±1.54,P〈0.01;MAR：1.12±0.19,1.45±0.24,P〈0.01）。结论：2,3,7,8-TCDD哺乳期暴露显著降低了仔鼠牙齿的矿化程度,严重阻碍了其矿化进程。     

Role of inheritability of tooth form, tooth malformation and tooth position

A common technique to divide the influence of heredity and environment on certain characteristics, or pathologies is the one that uses twins. There are more or less complex techniques to carry out twin research, from which the most simple procedure consists of determining the amount of concordance of certain characteristics in monozygotic (MZ) and dizygotic (DZ) twins. In individuals who develop from one oocyte, like MZ twins, one would expect a correlation of 1.00 (or 100% concordance) purely from their gene-relation. DZ twins are the result of separate conceptions of the same parents and they thus differ as much from each other as ordinary brothers and sisters. The most recently developed twin-methodologies use path analysis and model fitting for the estimations of the heritabilities and environmental influences on certain characteristics. In this article it is tried to picture the genetic an environmental influence on tooth form, tooth position and occlusal characteristics with different genetic techniques. Generally it can be concluded that our genes are of utmost importance for tooth form and tooth malformations, but the environment has a much bigger impact on tooth position and occlusal parameters.     

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目的探讨母鼠哺乳期2,3,7,8-四氯二苯并二恶英(2,3,7,8-TCDD)暴露对仔鼠牙齿超微结构的影响。方法于2009—2010年,在广东省口腔疾病临床实验室,通过母鼠颈部皮下注射2,3,7,8-TCDD溶液(10μg/kg)方法,建立哺乳期2,3,7,8-TCDD暴露模型,收集日龄60d仔鼠带有切牙的下颌骨作为实验样品。将日龄60d的实验组和对照组(母鼠颈部皮下注射玉米油)仔鼠的下切牙样本,经固定、脱水、喷金后行扫描电镜观察,并行牙本质小管直径以及釉柱直径的测量。结果实验组仔鼠的牙齿硬组织结构发生改变,出现组织缺陷和矿化不良结构。下切牙釉柱直径和牙本质小管直径,实验组均小于对照组,差异有统计学意义[釉柱直径比较:(5.74±1.13)μm对(6.08±1.74)μm,P<0.01;牙本质小管直径比较:(1.27±0.39)μm对(1.49±0.44)μm,P<0.01)]。结论母鼠哺乳期2,3,7,8-TCDD暴露破坏了子代大鼠牙齿的超微结构。     

Experimental tooth ankylosis and horizontal tooth movement in the pig

Experimental ankylosis was produced by 4 different techniques in deciduous premolar teeth of growing pigs. The most successful method was by thermal injury to the apex of the root. Measurements of the forward movement of the teeth were made on stone casts of the jaws taken prior to the production of ankylosis and after 16 weeks. Measurements from control animals showed no significant difference between right and left sides of the jaws. In those animals in which ankylosis developed, the distance between the premolar reference point and the incisor mid-point on the ankylosed side was always statistically significantly greater (mean 4.1 mm in maxilla and 2.4 mm in the mandible) than that from the contralateral unaffected side, indicating a forward movement of the deciduous premolar teeth. During the experimental period, the incisors moved forward on average by 20.0 mm in the maxilla and by 23.2 mm in the mandible whilst the deciduous canine moved forward by 9.7 mm in the maxilla and by 12.7 mm in the mandible. The differential movement of the 3 types of teeth and the presence of diastemata between the canine and incisors and between canine and premolars makes it impossible to accept a forward drive from the erupting molars as the motive force or that this forward movement is in response to interdental attrition. As the deciduous canines are small and do not occlude with teeth in the opposing jaw, it is also unlikely that occlusal forces could be responsible. Some of the forward movement of the canines and incisors is undoubtedly caused by the forward inclination of their line of eruption. The size of this contribution is not known. The direction of movement of the groups of teeth studied appeared to be wholly forward over the experimental period and was similar to that found in man.