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Premolar and molar root morphology in X chromosome aneuploidy

Premolar and molar root morphology was investigated in 40 females with Turner syndrome (TS) and 40 males with Klinefelter syndrome (KS). Healthy females and males, 80 in each group, served as controls. The aim was to investigate the influence of the X chromosome on dental root development. Root forms were analysed on orthopantomograms and, for the TS, also on periapical radiographs. Premolars were classified as proposed by Midtbo et al (1994). Taurodontism of lower molars was measured according to Shifman & Chanannel (1978). Multi- rooted maxillary and mandibular premolars were found significantly more often in TS group than in all other investigated groups (p < 0.000001). In maxilla there was 2.9% one- rooted, 88.2% two-rooted and 8.8% three- rooted P1 and 28.6% one-rooted, 65.3% two-rooted and 6.1% three-rooted P2. In mandible there was 21.6% one-rooted and 78.4% two-rooted P1, and 51.4% one-rooted, 47.3% two-rooted and 1.4% three- rooted P2 (part of results previously published). There was no difference in premolar root morphology between KS and male controls, or between female and male controls. Lower molars with supernumerary roots were found in 17 TS females (42.5%). Prevalence of taurodontism was 32.1% in KS group (sample size 28), 3.8% in control males (p< 0.00005), 2.5% in control females and 3.7% in TS females (sample size 27). The opposite findings in TS and KS indicate that root formation is influenced by the quantity of X chromosome genes with deficiency leading to division of premolar and molar roots, and supernumerary X chromosome leading to late division of molar roots resulting in taurodontism.

X chromosome ; Turner syndrome ; Klinefelter syndrome ; root morphology

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