Dental anomalies in children submitted to antineoplastic therapy

Cancer is the third most frequent cause of death in children in Brazil. Early diagnosis and medical advances have significantly improved treatment outcomes, which has resulted in higher survival rates and the management of late side effects has become increasingly important in caring for these patients. Dental abnormalities are commonly observed as late effects of antineoplastic therapy in the oral cavity. The incidence and severity of the dental abnormalities depend on the child''s age at diagnosis and the type of chemotherapeutic agent used, as well as the irradiation dose and area. The treatment duration and aggressivity should also be considered. Disturbances in dental development are characterized by changes in shape, number and root development. Enamel anomalies, such as discoloration, opacities and hypoplasia are also observed in these patients. When severe, these abnormalities can cause functional and esthetic sequelae that have an impact on the children''s and adolescents'' quality of life. General dentists and pediatric dentists should understand these dental abnormalities and how to identify them aiming for early diagnosis and appropriate treatment.     

Effectiveness of Reinduction and/or Dose Escalation of Ustekinumab in Crohn’s Disease: A Systematic Review and Meta-analysis

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揿针疗法联合镇痛药物对断指再植术后疼痛影响的效果分析

【 】 目的 通过探讨揿针疗法联合镇痛药物对断指再植术后疼痛影响的效果,以寻找能减轻患者疼痛且不良反应较小的方法,从而降低血管危象的发生。方法 选取我科2016年1月～2016年10月断指再植术后患者258例,随机分为对照组(n=129)和观察组(n=129)。对照组患者在术后常规使用塞来昔布联合曲马多缓释片口服用药加自控镇痛泵的西药镇痛。观察组在此基础上使用揿针疗法的中医操作,采取中西医结合疗法。观察两组患者治疗后的临床效果。结果 对照组疼痛程度高于观察组(P＜0.01);观察组在术后镇痛时不良反应的发生率明显少于对照组(P＜0.01);血管危象发生率由20.16%下降至5.43%(P＜0.01);术后1周睡眠时间观察组明显多于对照组(t=-8.65,P＜0.01);观察组加用补救药明显少于对照组(P＜0.01),比较2组差异具有统计学意义。结论 揿针疗法联合镇痛药物对缓解断指再植术后疼痛的效果显著,能有效降低使用镇痛药物后的不良反应,从而有效预防血管危象的发生,提高存活率,且安全、经济、方便,值得临床推广使用。     

急性血液稀释技术在动物实验围手术期中的应用

目的观察急性血液稀释技术(ANH)在狗断肢冷冻再植实验中对改善术中、术后动物全身状态的作用。方法在狗后肢深低温冷冻再植实验中,对照组(A组)采用静脉补充等量乳酸钠林格氏液,实验组(B组)采用急性血液稀释技术,对比两组各时点循环动力学指标、血常规、术后动物苏醒时间、抬头时间、站立时间、术后进食、进水时间。结果 1术中两组Pa O2、PCO2值均在正常范围,呼吸频率正常,B组心率明显低于A组,术中血红蛋白、红细胞压积输血前A组与B组无统计学差异,术后B组明显高于A组,差异存在显著性。2术后动物苏醒时间、抬头时间、站立时间、术后进食量、进水量B组均明显优于A组,存在显著差异。结论在狗断肢深低温冷冻再植实验中,急性血液稀释技术(ANH)能明显改善动物术中的全身状态,加快术后恢复速度。     

Postnatal Lower Jaw Dentition in Different Phenotypes of Tabby Mice

The tabby (Ta) syndrome in mouse is homologous to human anhidrotic ectodermal dysplasia, including defective development of hair, teeth, and glands. To complete the available data on the functional dentition in the Ta mice, we analyzed the mandibular cheek teeth in 261 postnatal specimens arranged in several phenotype/genotype groups: 51 Ta -hemizygous males, 56 Ta -homo/hemizygous females, 64 Ta -heterozygous females, and 40 and 50 wild-type control males and females, respectively. We evaluated tooth number, size, shape and eruption and compared these parameters in the different groups. In any individual group of Ta mice, there was variability mainly in the size and shape of the most mesial tooth and in the tooth patterns. The incidence of a reduction in tooth number in homozygous and hemizygous mice was dependent on the breeding scheme.     

Pathways and Fate of Migratory Cells During Late Tooth Organogenesis

Tissue recombination experiments and cell lineage analyses of the developing neural crest have documented the role and central pathways of migratory cells during early craniofacial development. In the present study, regional pathways of cells during late peripheral morphogenesis were investigated using the crown stage tooth organ as a model. Homing targets during tooth integument formation were analyzed to understand the fate of migratory cells involved in late tooth organogenesis and the developmental origin of periodontal tissues. After surgical removal of the oral mucosa, the oral aspect of the dental follicle of lower first mouse molar teeth was labeled using a fluorescent contact dye. Following sacrifice after 0, 2, 4, and 6 days, labeled cells were detected in the dental follicle, in the alveolar bone, and in the periodontal ligament adjacent to the molar root. The distribution of labeled tissues was reconstructed three-dimensionally via confocal microscopy. Using a tooth molar organ culture system, labeled cells within the dental follicle were documented traveling in the apical direction. Our results indicated that cell migration during tooth organogenesis was following specific pathways and that cells within the circumference of the dental follicle were migrating in the apical direction. We speculate that migratory cells passing through the dental follicle connective tissue may contribute to the formation of the periodontium. The present documentation visualizes pathways, role, and dynamics of extensive cell movements during late tooth organogenesis.     

Over- and Ectopic Expression of Wnt3 Causes Progressive Loss of Ameloblasts in Postnatal Mouse Incisor Teeth

Intercellular signaling is essential for the development of teeth during embryogenesis and in maintenance of the continuously growing incisor teeth in postnatal rodents. WNT intercellular signaling molecules have been implicated in the regulation of tooth development, and the Wnt3 gene shows specific expression in the enamel knot at the cap stage. We demonstrate here that Wnt3 also is expressed in specific epithelial cell layers in postnatal incisor teeth. To begin to delineate the functions of Wnt3 in developing and postnatal teeth, we determined the effects of over- and ectopic expression of Wnt3 in the tooth epithelium of mice carrying a keratin 14- Wnt3 transgene. Expression of the transgene caused a progressive loss of ameloblasts from postnatal lower incisor teeth. Loss of ameloblasts may be due to defective proliferation or differentiation of ameloblast precursors, progressive apoptosis of ameloblasts, or loss of ameloblast stem cells.     

Minimal tooth preparation for posterior monolithic ceramic crowns: Effect on the mechanical behavior,reliability and translucency

ObjectiveDespite the increased use of monolithic crowns, their performance has yet to be determined when the minimal tooth preparation (MTP) principle is considered. The goal of this study was to evaluate the effect of MTP on the mechanical behavior, reliability and translucency of posterior monolithic ceramic crowns.MethodsDentin analogues were machined using two preparation designs (0.5 or 1 mm reduction) to receive first molar crowns in order to evaluate the monolithic crown performance. Next, 126 crowns were divided (21/g) according to the material (High translucent zirconia – YZHT, Zirconia reinforced lithium silicate – ZLS and Hybrid ceramic – HC) and thickness (0.5 or 1 mm). Tensile stress concentration was calculated using the finite element method. The crowns were adhesivelly cemented and step stress fatigued to calculate reliability for missions at 600 and 1000 N. Translucency was analyzed in 10 discs of each material and thickness.ResultsHigher stress concentration was found in thinner crowns and those with higher elastic modulus. YZHT crowns were suspended when fatigue reached 1500 N load, thus 1-parameter Weibull was used to analyze the data. Reliability was only affected by thickness at 1000 N. ZLS.5 showed lower survival than HC.5, which was similar to the groups that presented 100% survival. YZHT showed the highest strength and data scattering. ZLS1 (22.3 ± 1.4) presented higher translucency than HC1 (19.2 ± 0.6) and YZHT1 (12.0 ± 2.9), whereas ZLS.5 and HC.5 were similar to each other (26.5 ± 2.3, 26.7 ± 2.2) and superior to YZHT.5 (12.7 ± 1.2).SignificanceHC.5 combined high reliability and translucency with low stress concentration, yielding better crown performance and tooth preservation.     

Substantial regional differences in the biomechanical behavior of molar treated with selective caries tissue removal technique: a finite element study

ObjectivesSelective caries removal (SCR) is recommended over non-selective removal for managing deep carious lesions to avoid pulp exposure and maintain pulp vitality. During SCR, residual carious dentin is left behind and sealed beneath the restoration. The biomechanical effects of such residual lesions on the restored tooth remain unclear and were assessed using finite element modeling (FEM).MethodsBased on μ-CT images of a healthy permanent human third molar, we developed five finite element models. Generic class I and II cavity restorations were modeled where residual lesions of variable sizes were either left or fully removed on occlusal and proximal surfaces. The cavities were restored with adhesive composite. All 3D-FE models were compared with a model of a healthy, non-treated molar. A vertical load of 100 N was applied onto the occlusal surface.ResultsRegardless of the lesion size, in molars with occlusal lesions higher mean stresses were predicted along the filling-lesion interface than in all other models. The smallest occlusal lesion (Ø₁ = 1 mm) resulted in the highest maximum stresses at the filling-lesion interface with large stress concentrations at the filling walls indicating failure risk. In conclusion, lesion site and extent are influencing parameters affecting the filling-lesion interactions and thus the biomechanical behavior of the tooth after SCR.SignificanceRetaining carious lesions around the pulpal floor affects the deformation and stress states in tooth-filling complexes. The higher stresses observed in molars with occlusal lesions may affect restoration stability and longevity. Suprisingly, more extended occlusal lesions may provide a more favorable tooth performance than less extended ones. In contrast, in molars with proximal lesions the residual lesion had only limited effect on the tooth’s biomechanical condition.