The growth hormone receptor gene is associated with mandibular height in a Chinese population

Genetic influences are important in the determination of mandibular morphology, and growth hormone receptor (GHR) is believed to have an important influence on the growth of craniofacial bone. In this study, we used quantitative trait locus methods to evaluate the relationship between craniofacial morphology and single-nucleotide polymorphisms (SNPs) in GHR in an unselected healthy Chinese population. We systematically screened the 10 exons and nearby introns of GHR and identified 6 SNPs. Using 4 SNPs as markers, we studied the relationships between genotypes and craniofacial linear measurements. Individuals with the genotype CC of polymorphism I526L had a significantly greater mandibular ramus length (condylion-gonion/ articulare-gonion) than those with genotype AC or AA. Haplotype analysis showed that there were also significant differences between the long and short mandibular height groups in an extreme population. Our results indicate that the GHR gene polymorphism I526L is associated with mandibular height in the Chinese population.     

Erosion of deciduous and permanent dental hard tissue in the oral environment

OBJECTIVES: The objectives of this study were two-fold: (1) to determine (by surfometry) loss of deciduous and permanent enamel and dentine following consumption of a single low pH orange drink for 15days; and (2) to determine (by surfometry) loss of deciduous and permanent enamel and dentine following consumption of the product 2 versus 4 times per day for 15days. METHODS: Sixteen healthy volunteers participated in a single centre, single blind, 2-phase crossover study, conducted according to Good Clinical Practice, and employing the validated model described by West and co-workers (Journal of Dentistry 1998; 26:329-335). RESULTS: In all tissues, erosion was progressive over time, the pattern being more linear in enamel than in dentine. In general, erosion of deciduous enamel was greater than that of permanent enamel, though this difference was significant only for those specimens exposed to 4 drinks per day. Conversely, erosion of dentine was generally greater in the permanent tissue, though differences rarely reached conventional levels of statistical significance. Increasing frequency of consumption resulted in increased loss of tissue, but this difference was neither proportional nor consistently statistically significant. CONCLUSIONS: It is concluded that statistically significant differences in susceptibility of deciduous and permanent enamel to erosion appear to emerge over time and with increasing frequency of consumption. This is of importance clinically given the reduced dimensions of the deciduous dentition and the element of 'abuse' of soft drinks by the child population. Further development of soft drinks with low erosive potential is recommended.     

口腔环境因素对血型链球菌和变形链球菌生长的影响：I.粘蛋白的影响

采用连续培养方法，以粘蛋白作为化学限定培养基中的限定性因子，观察血型链球菌（以下简称血链菌）和变形链球菌（以下简称变链菌）Ｉｎｇｂｒｉｔｔ（ｃ）的生长状态。结果显示变链菌不能生长于以粘蛋白作为唯一营养源的培养基中，而血链菌可以生长；两菌混合培养时的生长量均有所提高，表明两菌有协同降解粘蛋白作用。     

Dental caries in adult and elderly Chinese

This paper reports on a study of dental caries conducted among 1744 urban and rural Chinese (from 20 to 80 years old), who were selected by means of a systematic stratified sampling procedure. The prevalence of one or more decayed or filled teeth ranged from 48 to 90% in urban residents, and from 51 to 97% in rural residents, depending on age. The mean number of decayed or filled teeth ranged from 1.2 (+/- 1.9) among 20-29-year-olds, to 6.2 (+/- 5.5) among 70+-year-olds, and was highest among rural residents. Among 20-29-year-olds, the main components of the DFT were enamel lesions and fillings. Among 30-49-year-olds, the DFT consisted mainly of enamel lesions and filled teeth, as well as teeth with lesions involving the pulpal tissues. In subjects over the age of 50 years, lesions involving pulpal tissues were the predominant type, followed by root-surface lesions. In subjects below the age of 50 years, most of the caries experience derived from coronal surfaces, particularly occlusal surfaces. Root-surface caries was predominantly a feature of persons aged 50 years and above. Despite a large number of surfaces being at risk of root-surface caries, less than 10% of the surfaces were so affected. Although cross-sectional in nature, these data indicate that when the oral hygiene standards are poor, caries lesions continue to develop and progress throughout life. With age, dental caries becomes a substantial oral health problem in this population of adult and elderly Chinese, despite the availability of some dental services.     

Expression and characterization of a Rana pipiens amelogenin protein

Amelogenin, the major protein of developing enamel matrix, controls enamel crystal growth via unique supermolecular features. While much has been contributed to our understanding of mammalian amelogenin function, little is known about how amelogenin and its unique physico-chemical features have evolved among vertebrates. Here we report, for the first time, amphibian amelogenin recombinant protein expression and characterization in Rana pipiens . In order to characterize R. pipiens amelogenin, the newly discovered amelogenin coding sequence was amplified, subcloned, and expressed in Eshcerichia coli . Our newly generated R. pipiens amelogenin-specific antisera resolved a major 19-kDa band on western blots of frog tooth extracts and revealed an enamel organ tissue-specific localization pattern using immunohistochemistry. Using mass spectroscopy, a single major compound with a molecular weight of 21.6 kDa was detected, which corresponded to the amino acid sequence-based molecular weight prediction of the His fusion recombinant protein. Dynamic light scattering studies resolved 41-nm radius subunits compared with 14-nm radius subunits from mouse recombinant amelogenin controls. Transmission electron microscopy revealed defined spherical subunits in R. pipiens matrix self-assembly in contrast with a homogeneous 'stippled' matrix in mouse amelogenin matrix self-assembly. Our data suggest that R. pipiens amelogenin is distinguished from mammalian amelogenins by a number of unique physico-chemical properties which may be related to specific modes of crystal formation in frog enamel.     

In vivo evaluation of the trabecular bone behavior to porous electrostatic spray deposition-derived calcium phosphate coatings

OBJECTIVES: Electrostatic spray deposition (ESD) is a new technique to deposit calcium phosphate (CaP) coatings. The aim of the present study was to evaluate the bone behavior of ESD CaP-coated implants with various degrees of crystallinities in the trabecular bone of the femoral condyle of goats. MATERIAL AND METHODS: Using the ESD technique, thin porous CaP coatings were deposited on tapered, conical, screw-shaped titanium implants. Three different heat-treatments were applied, resulting in amorphous CaP (400 degrees C, ESD1), crystalline carbonate apatite (500 degrees C, ESD2), and crystalline carbonated hydroxyapatite (700 degrees C, ESD3). Implants were inserted into the trabecular bone of the femoral condyles of goats for 12 weeks, and titanium (Ti) implants served as controls. RESULTS: The results showed that ESD-derived coatings are osteocompatible. Histomorphometrical analysis showed that the application of a CaP coating resulted in more bone contact along the press-fit area of the implant compared with the Ti implants. Moreover, the percentage bone contact of the ESD3-coated implants was increased, compared with the Ti control group. Regarding the other coatings, no differences were found compared with the control group. CONCLUSION: Crystalline carbonated hydroxyapatite ESD-coated implants positively influenced the biological performance compared with Ti control implants.     

Laboratory interproximal access efficacy and gingival margin cleaning of the elmex SENSITIVE SOFT, EXTRA SOFT and ADA reference toothbrushes

OBJECTIVE: The purpose of these laboratory studies was to evaluate three toothbrushes for their ability to remove artificial plaque deposits at interproximal sites and along the gingival margin of simulated anterior and posterior teeth, using horizontal and vertical brushing motions. METHODOLOGY: Three toothbrushes were evaluated: elmex SENSITIVE SOFT; elmex SENSITIVE EXTRA SOFT; and the ADA reference. Twenty-four tests on each toothbrush group were conducted, and results were statistically analyzed using ANOVA and the post hoc Tukey test. RESULTS: In both the interproximal access efficacy and gingival margin cleaning assays, the elmex SENSITIVE EXTRA SOFT and SENSITIVE SOFT toothbrushes were statistically superior (p < 0.001) to the ADA reference toothbrush. CONCLUSION: The elmex SENSITIVE SOFT and EXTRA SOFT toothbrushes are predicted to offer excellent plaque removal efficacy interproximal areas and along the gingival margin of both anterior and posterior teeth.     

Laboratory assessment of the Sensodyne Mikro Aktiv extra soft toothbrush and the Oral-B indicator soft toothbrush

OBJECTIVE: The objective of this laboratory study was to assess the Sensodyne Mikro Aktiv extra soft toothbrush, compared with the Oral-B Indicator soft toothbrush, for interproximal access efficacy (IAE). METHODS: Six toothbrushes of each product were tested four times, for a total of twenty-four tests on each toothbrush design. In the IAE assay, the tooth brushing technique involved independent evaluations of each toothbrush in a vertical or horizontal brushing motion, tooth shapes simulating anterior and posterior teeth, and a brushing weight of 250 g. The brushing apparatus was set to brush for 15 seconds at two strokes per second with a 50 mm stroke. All readings were measured with 3x magnification by a single investigator. RESULTS: The mean IAE value on anterior tooth shapes, with vertical and horizontal brushing, was significantly (p < 0.001) higher for the Sensodyne Mikro Aktiv toothbrush than for the Oral-B Indicator toothbrush. When the IAE values were combined to give an overall brushing average, the Sensodyne Mikro Aktiv toothbrush was significantly (p < 0.001) higher compared to the Oral-B Indicator toothbrush. CONCLUSION: The Sensodyne Mikro Aktiv toothbrush has demonstrated superiority to the Oral-B Indicator toothbrush for access into interproximal areas using this laboratory methodology.