engleski

MOLAR CROWN MORPHOLOGY IN GONADAL DYSGENESIS

Introduction. Different studies in patients with sex chromosome aberrations have shown that the genes located on sex chromosomes have influence on dental development, including both tooth size and shape. However, the data on tooth morphology are scanty and not easy to compare because different criteria are used. Aim. The aim of this paper was to evaluate the influence of the X-chromosome on permanent molar crown morphology. Materials and method. The material comprised 40 Turner syndrome (TS) patients and 40 Klinefelter syndrome (KS) patients from the population of the former Yugoslavia, mainly from Croatia, where they received medical treatment. Karyotypes determined in the TS patients were 45, X (n = 25) ; 45, X/46, X, fr(X) (n = 1) ; 45, X/46, X, r(X) (n = 3) ; 45, X/46, X, i(Xq) (n = 3) ; 46, X, i(Xq) (n = 2) ; and 45, X/46, XX (n = 6). The following karyotypes were determined in the patients with Klinefelter syndrome: 47, XXY (n = 37) ; 47, XXY/46, XY (n = 2) ; and 47, XXYq+ (n = 1). The control group consisted of clinically healthy females and males, 80 in each group. The investigation of molar crown morphology was performed on dental plaster casts using the Arizona State University dental anthropology system. The evaluated traits were metacone, hypocone, metaconule, Carabelli&#8217; s trait, parastyle and peg-shaped molar for upper molars ; anterior fovea, groove pattern, cusp number, deflecting wrinkle, distal trigonid crest, protostylid, hypoconulid, tuberculum sextum, tuberculum intermedium and middle trigonid crest for lower molars. All upper and lower molars were investigated: first (M1), second (M2) and third (M3) molar. The measurements were repeated on 50 casts for a calculation of intra- and interobserver concordance. The results of morphological features were analysed by log-linear analysis. Results and discussion. The metacone was more pronounced in M1 and M2 in the control males but with a low significance level (p<0.05). The hypocone was significantly reduced in the TS patients (p<0.0001). In the KS patients the hypocone was more pronounced in M1, but in M2 and M3 reduced forms were more frequent than in the controls (p<0.0001). The metaconule was more pronounced in the KS patients (p<0.05). Carabelli&#8217; s trait was equally frequent in M1 in females (62% TS patients and 76% controls) but in M2 more frequent in the TS group - 38% opposed to 10% (p<0.05). Because of the critical level of evaluation error, results for M1 have to be considered with caution. In the KS group the trait was found in 83% M1, 29% M2 and 25% M3, which was more frequent than in the controls (p<0.01). A reduction of the cusp number and of the size of the hypoconulid was specific to the TS group (p<0.05). The deflecting wrinkle was more pronounced in the KS group (p<0.000001), even if the results for M1 had been omitted because of the high error rate. The protostylid was more frequent in the TS group (p<0.05) and the KS group (p<0.01) than in the controls. The results of an intraobserver error calculation were concordant to those reported by Nichol & Turner II. However, it compromised findings for Carabelli&#8217; s trait, anterior fovea and deflecting wrinkle in M1. For that reason, and because of the modest number of first molars undamaged with caries and wear, we have rejected findings for the anterior fovea completely. Our findings are concordant with the previously reported molar size reduction in TS and the increase in first molar size in KS, which manifests itself through the expression of hypocone, metaconule, cusp number and hypoconulid. We found no evidence of simplification of the molar crown - complex morphology with accessory cusps characterizes both syndrome groups. Conclusion. Investigation affirmed that the genes located on the X chromosome have a significant influence on molar morphology.

molar; crown morphology; X chromosome; gonadal dysgenesis

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