Dolores Biočina-Lukenda

Dental age estimation using Demirjian and Willems methods: Cross sectional study on children from the Former Yugoslav Republic of Macedonia

To evaluate applicability of Demirjian and Willems methods for calculating dental age of children in the Former Yugoslav Republic of Macedonia we analyzed panoramic radiographs of 966 children (485 female and 481 male, aged 6-13 years) treated at the University and Community Dental Clinics in Skopje using four Demirjian methods and a Willems method for determining dental ages. Intra-rater and inter-rater agreement of mineralization stages were 0.86 and 0.82, respectively. All methods significantly overestimated dental age when compared to the chronological age (p<0.001). In males, the lowest overestimation was shown using Willems method (0.52±0.87 years), followed by Demirjian methods from 1976 using PM1, PM2, M1, M2 teeth (0.69±0.92 years) and using I2, PM1, PM2, M2 teeth (0.80±0.98 years). The greatest overestimation were shown using Demirjian methods using 7 teeth from 1976 (0.92±0.99 years) and method from 1973 (1.06±1.07 years). In females, the lowest overestimation was shown using Willems method (0.33±0.83 years) than the Demirjian method using PM1, PM2, M1, M2 teeth (1.00±1.01 years), following methods from 1976 using 7 teeth (1.03±1.01 years) and I2, PM1, PM2, M2 teeth (1.12±0.96 years). The greatest overestimation was for method from 1973 using 7 teeth (1.17±0.98 years). Willems method was the most accurate while Demirjians methods for dental age calculation are not suitable on children from the Former Yugoslav Republic of Macedonia.

Spatial and temporal distribution of Ki-67 proliferation marker, Bcl-2 and Bax proteins in the developing human tooth

OBJECTIVE To investigate the spatial and temporal expression of proliferation Ki-67 marker, pro-apoptotic Bax and anti-apoptotic Bcl-2 proteins during early development of the human tooth. MATERIALS AND METHODS Histological sections of eight human conceptuses, 5-10 postovulatory weeks old, were used for immunolocalization for Ki-67, Bax and Bcl-2 markers. Quantification was performed by calculating the fraction of Ki-67 positive cells, expressed as a mean ± SD, and analysed by Mann-Whitney test, Kruskal-Wallis and Dunns post hoc test. RESULTS In 6th-7th developmental weeks, the tooth germ and dental crest contained 37% of proliferating cells, which increased to 40% in the 8th week, and then decreased to 15% in the 10th week, whilst the proliferation in the ectomesenchyme subsequently dropped from 37% to 23%. Epithelial parts of the enamel organ displayed similar proliferation activity (31-36%), dental crest 10%, whilst enamel knot showed no proliferating activity. The tooth ectomesenchyme contained more proliferating cells (50%) than the jaw ectomesenchyme (35%), and both dropped to 28% in the 10th week. Ectomesenchyme between the tooth germs contained 23%, whilst the jaw ectomesenchyme contained 15% of proliferating cells. Bcl-2 expression had following pattern: strong in proliferating cells, moderate in tooth germs and dental crest, and weak in the ectomesenchyme. Bax co-expressed with Bcl-2 in the tooth germ and dental crest. In the reticulum and inner enamel epithelium Bcl-2 had prevalent expression, whilst Bax prevailed in the outer enamel epithelium and tooth ectomesenchyme. CONCLUSIONS Proliferating cells most likely influence growth of the tooth germ, Bcl-2 affects proliferation and differentiation of specific cell lineages, whilst Bax influences process of cell death.

Expression of Ki-67, Oct-4, γ-tubulin and α-tubulin in human tooth development

AIMS To analyze factors controlling cell proliferation and differentiation, and appearance of primary cilia during the cap and bell stages of incisor or/and canine human enamel organs. MATERIALS AND METHODS Qualitative and quantitative analysis of proliferating Ki-67 positive cells and expression of γ-tubulin, α-tubulin and Oct-4 was immunohistochemically analyzed in the cap an bell stages of 10 developing human incisor and canine germs, 8-21 weeks old. RESULTS During the analyzed period, ratio of Ki-67 positive cells changed in outer enamel epithelium from 48.86% to 24.52%, in inner enamel epithelium increased from 56.11% to 60.06% and then dropped to 44.24%. While in dental papilla proliferation first increased from 46.26% to 55.45%, and then dropped to 22.08%, a constant decrease of proliferation characterized enamel reticulum (from 46.26% to 15.49%). Strong cytoplasmic Oct-4 expression characterized epithelial parts of enamel organ, particularly the differentiating ameloblasts. During further development, Oct-4 expression shifted to both nuclear and cytoplasmic expression in mesenchymal tooth components. Primary cilia characterized most of the cells in developing enamel organ. While non-ciliated (proliferating) cells mainly contained two centrioles (γ-tubulin), the primary cilia (α-tubulin) were arising from basal bodies (γ-tubulin) of non-proliferating cells. CONCLUSIONS We suggest that increase in cell proliferation enables growth of enamel organ, while its selective decrease leads to disintegration of some tooth parts. Drop of proliferation coincided with initiation of ameloblast and odontoblast differentiation. Additionally, cell differentiation was accompanied by increased expression of Oct-4 and probably by signalling via primary cilia, both regulating processes of cell proliferation and differentiation.

Analysis of the elective curriculum in undergraduate medical education in Croatia

Medical Education 2010: 44: 387–395

Micronucleus, alkaline, and human 8-oxoguanine glycosylase 1 modified comet assays evaluation of glass-ionomer cements - in vitro

Abstract The purpose of this study was to evaluate the genotoxic potential of components leached from two conventional self-curing glass-ionomer cements (Fuji IX and Ketac Molar), and light-curing, resin modified glass-ionomer cements (Vitrebond, Fuji II LC). Evaluation was performed on human lymphocytes using alkaline and hOGG1 modified comet, and micronucleus assays. Each material, polymerised and unpolymerised, was eluted in extracellular saline (1 cm2 mL-1) for 1 h, 1 day, and 5 days. Cultures were treated with eluates using final dilutions of 10-2, 10-3, and 10-4. Alkaline comet assay did not detect changes in DNA migration of treated cells regardless of the ionomer tested, polymerisation state, and elution duration. Glass ionomers failed to significantly influence micronucleus frequency. No oxidative DNA damage in treated lymphocytes was observed using hOGG1 modified comet assay. Obtained results indicate high biocompatibility of all tested materials used in the study under experimental conditions. Sažetak Svrha istraživanja bila je procijeniti genotoksični potencijal komponenata koje izlučuju dva konvencionalna samopolimerizirajuća stakleno-ionomerna cementa (Fuji IX i Ketac Molar) te svjetlosno polimerizirajući i smolom modificirani stakleno-ionomerni cementi (Vitrebond, Fuji II LC). Istraživanje je provedeno na ljudskim limfocitima primjenom alkalnog komet testa, komet testa modificiranog hOGG1 enzimom te mikronukleus testa. Svaki materijal, polimerizirani i nepolimerizirani, eluiran je u fiziološkoj otopini (1 cm2 mL-1) tijekom jednog sata, jednog dana i tijekom 5 dana. Kulture limfocita tretirane su eluatima u razrjeđenjima 10-2, 10-3 i 10-4. Alkalnim komet testom nisu zabilježene promjene u migraciji DNA iz tretiranih stanica bez obzira na ispitani ionomer, vrstu polimerizacije i trajanje elucije. Izloženost staklenim ionomerima nije značajno utjecala na učestalost mikronukleusa. Primjenom hOGG1 modificiranog komet testa nije zamijećeno oksidativno oštećenje DNA u tretiranim limfocitima. Dobiveni rezultati upućuju na visoki stupanj biokompatibilnosti svih testiranih materijala koji su se koristili u eksperimentalnim uvjetima.