五倍子水提取物对正常釉质及去有机质釉质脱矿影响的实验研究

目的：探讨五倍子水提取物影响牙釉质脱矿的机理。方法：建立去有机质釉质模型,分别以30mg／ml五倍子水提取物、2％氟化钠、38％氟化氨银、10％硝酸银及去离子水处理去有机质釉质及正常釉质,采用化学法制备釉质人工龋。分别收集各组脱矿液,以原子光谱法检测脱矿液中钙、磷含量。脱矿后釉质进行显微放射照相分析,比较其脱矿量及龋损深度。结果：与氟化氨银及硝酸银组相同,五倍子水提取物对正常釉质抑制脱矿的效果显著优于去有机质釉质。氟化钠及去离子水对正常釉质及去有机质釉质抑制脱矿效果无显著性差异。结论：有机质在一定条件下可抑制釉质脱矿;五倍子通过作用于釉质有机质达到抑制釉质脱矿的作用。     

釉基质蛋白对牙周细胞抗炎作用的研究进展

釉基质蛋白(enamel matrix protein,EMP)促进牙周组织再生的作用已得到大量研究证实。近来,随着EMP的研究进展,其抗炎作用也逐渐被发现。本文就EMP对多种牙周相关细胞的抗炎作用作一综述。     

Background factors of molar-incisor hypomineralization in a group of Finnish children

Objective. Molar-Incisor Hypomineralization (MIH) is a common developmental enamel defect characterized by demarcated opacities in permanent molars and incisors. Its etiology still remains unclear. The aim of this retrospective cohort study was to assess if the socioeconomic environment of the child is associated with MIH. Materials and methods. The study was located in two rural towns and three urban cities in Finland. A total of 818 children, between 7–13 years old, were examined for MIH using the evaluation criteria in line with those of the European Academy of Paediatric Dentistry, but excluding opacities smaller than 2 mm in diameter. The mothers filled in a questionnaire which included questions related to the family’s way of living (e.g. area of residency, farming, day care attendance) and socioeconomic status (family income, number of mother’s school years, level of maternal education). Results. The prevalence of MIH in the study population was 17.1%. Family income, urban residency and day care attendance were associated with MIH in the univariate analysis. In the multivariate analysis using binary logistic regression, only urban residency during a child’s first 2 years of life remained associated with MIH. The prevalence of MIH in urban areas was 21.3% and in rural areas 11.5% (OR = 2.18, CI = 1.35–3.53, p = 0.001). Conclusions. The prevalence of MIH was related to urban residency and could not be explained by any other factor included in the study.     

Aspects of the final phase of enamel formation as evidenced by observations of superficial enamel of human third molars using scanning electron microscopy

ObjectiveEnamel structure reflects ameloblast function. By studying the structure of the superficial enamel, information about ameloblast function toward the end of the secretory stage may be obtained.DesignThe superficial enamel in midcoronal areas of acid-etched facio-lingual sections from human third molars was studied in the scanning electron microscope (SEM).ResultsA great variation was observed in occurrence of prism-free enamel. Prism-free enamel dominated in 40% (mandibular) and 47% (maxillary) of observed areas and had a mean thickness of about 30 μm. Striations in the prism-free enamel had an interstriae distance of about 3.3–3.8 μm. The angle between prisms and enamel surface was about 60°, between prisms and Retzius lines about 45° and between Retzius lines and enamel surface about 15°. The distances between regularly occurring Retzius lines and between striations in the prism-free enamel both tended to decrease toward the enamel surface. Prisms could change direction as they approached the enamel surface, mostly in cervical direction. Where Retzius lines curved and converged occlusally, prisms tended to deviate in an occlusal direction.ConclusionsJudged from the incremental lines and occurrence of prism-free enamel, ameloblasts slow down and tend to lose their Tomes’ process as they approach the end of secretion. The crystals of prism-free enamel belong to the same system as the interprism crystals of prismatic enamel. A method, based on the disposition of fine incremental lines, is suggested for evaluation of ameloblast dynamics in the last stage of enamel secretion.     

Developmental changes of the vasculature in the periodontal ligament of rat molars: a scanning electron microscopic study of microcorrosion casts

Vascularization of the periodontal ligament was examined in developing upper first molars of rats from 5 to 30 d after birth with light and scanning electron microscopy. Formation of the vascular network in the periodontal ligament (PDL) started with the beginning of root formation. The PDL vessels derived from the basal region of the tooth germ ran parallel to the long axis of the root and connected with the vascular network of the enamel organ at the cervical end. The boundary of these 2 networks was initially indistinct but became clearer with the progress of root formation. The PDL vessels further elongated longitudinally and connected with each other by lateral branches to form a coarse mesh. Other vessels derived from the alveolar bone via Volkman's canals also contributed to the vascular construction of the PDL. The vessels from the alveolar bone provided branches to the existing mesh of the PDL. Consequently, the vascular network of the PDL consisted of vessels from 2 sources: 1 derived from the basal region of the tooth germ, and the other from the alveolar bone. The density of the vascular network reduced with the progress of root formation, especially at the middle part of the root, but the mesh at the apical region maintained a basket-like structure.     

Comparison of ready-to-use EMDOGAIN®-gel and EMDOGAIN® in patients with chronic adult periodontitis

OBJECTIVES: The aim of this multicenter trial was to compare the clinical and radiographical outcome of a ready-to-use Emdogain-gel (test) with the marketed Emdogain (control). METHODS: Subjects with bilateral infrabony defects > or =4 mm deep and > or =2 mm wide according to radiographs were selected. 88 subjects with probing pocket depth (PPD) > or =6 mm > or =1 month after supervised oral hygiene and scaling participated. At baseline plaque index, bleeding on probing, PPD and probing attachment level were recorded and reproducible radiographs for computer-based bone level measurements were taken. In each subject, 1 tooth was randomly treated with the test and 1 tooth with the control gel. Examinations were repeated 8 and 16 months post-operatively. RESULTS: After 16 months, the mean test PPD was 4.1 mm and the mean control PPD 4.2 mm. The mean gain of attachment was 2.7 mm for test and 2.9 mm for the control sites, and the radiographic measurements demonstrated a mean gain of 1 mm for both test and control sites. CONCLUSION: This series of cases demonstrated a statistically significant reduction of pocket depths and gain of attachment and bone after 8 and 16 months with no difference between the 2 preparations.     

Experimental study of brackets adhesion with a novel enamel-protective material compared with conventional etching

IntroductionA reliable adhesion between fixed devices and dental surfaces is a key factor for the clinical success of any orthodontic treatment. Adhesion preparation is associated with damages related to abrasive cleaning, enamel structure defacing caused by etching, enamel loss when removing resin remnants at orthodontic treatment finishing stage or when conditioning surface for adhesive failure and fractures at bracket removal.AimThe objective of this study was to compare the shear bond strength of metallic brackets to enamel adhered with a novel non-damaging and remineralizing material for enamel versus the traditional 37% phosphoric acid etching.Material and methods75 Premolars collected from 15- to 40-years old healthy donors requiring extraction were collected. The teeth were then randomly divided into three groups (n = 25). One group was used for the experimental new method (EX), the second for the conventional phosphoric acid etching (PA) method and the third group was left without any treatment (NT). The metallic brackets were fixed with Transbond® XT adhesive and composite resin polymerized for 40 s with a halogen photocuring lamp. The shear bond strength was quantified by means of a universal testing machine at 1 mm/min crosshead speed and a load cell of 1 kN.Statistical analysis usedTests of normality, adjustment of the data to a root square, a one-way ANOVA and Tukey tests were performed.ResultsStatistically significant differences between the NT (1.4 MPa), PA (32.1 MPa) and EX (9.7 MPa) groups were observed.ConclusionsThe experimental material for conditioning human enamel induces calcium phosphates crystals on the enamel surface and improves the bond strength in comparison to the NT group.