DEVETOGODIŠNJAKA SA NEUTROOKLUZIJOM CEPHALoMETRIC STANDARDS FoR 9 YEAR-oLD SERBIAN CHILDREN wITH NEUTRooCCLUSIoN

Uvod. Populacije pokazuju razlike u raznim detaljima facijalne morfologije. Ove razlike su lako uočljive kada se porede pojedinci različite etičke pripadnosti. Cilj rada. Uspostaviti specifične kefalometrijske standarde među polovima za srpsku decu uzrasta od devet godina. Materijal i metode. Trideset šest dečaka i četrdeset dve devojčice (prosečne starosti 9±0.35), srpske nacionalnosti, izabrani su na osnovu sledećih kriterijuma: molarni odnos I klase, pozitivan horizontalni i vertikalni preklop manji od 4mm, nepostojanje ukrštenog zagrižaja, bukalnog ili oralnog promašaja, adekvatna količina prostora u oba zubna niza, bez prethodne ortodontske terapije, bez vidljivih asimetrija. Analizirani su profilni telerendgen snimci svakog pacijenta po dva puta. Opisna statistika (srednja vrednost, standardna devijacija, minimum, maksimum) izračunata je za sve merene parametre. Rezultati su objavljeni u poređenju sa drugim normama bele populacije. Dobijeni podaci su prezentovani u tabelama. Rezultati. Poređenje među polovima uključuje dužinu prednje kranijalne bazе (sella-nasion), prednju visinu lica (nasion-menton), dužinu corpusa maxile, ugao maksilarnog prognatizma (SNA), ugao mandibularnog prognatizma (SNB), kao i ugao mandibule prema prednjoj kranijalnoj bazi (SN/MP). Zaključak. Srpski dečaci od devet godina imaju dužu prednju kranijalnu bazu, duži korpus maksile i veću prednju visinu lica, dok su maksila i mandibula više protrudirane kod devojčica.

background.Chinese people have more dental protrusion, have shorter midfacial length and steeper mandibular plane, compared to their British Caucasian counterparts 1 Huang et al. compared Americans of African and Europe an descent living in Birmingham and demon strated greater bidentoalveolar protrusion in the African American sample 2 .Some studies show that differences also exist among populations of the white race 3,4 .Trenouth.et al. compared craniofacial morphology in Dutch, English and American samples and concluded that the greatest differences were observed between the English and Dutch groups 3 .

Material and Methods
We visited two randomly selected schools, one in Pančevo, another in Belgrade -and in formed principals and teachers of our research plan.We handed out questionnaires containing details of the procedures to be carried out as well as the purpose of the research to all parents of the second grade children.Both school agreed to participate in the research, so we chose four second grade classes with 22 children each, with similar socioeconomic status.The basic criteria for selection were: Class I molar relationship, lack of crossbite, lack of oral and bucal failure, positive overjet and overbite less than 4 mm, no previous orthodontic treatment, adequate space in dental arches, no visibly asymmetry.Of the selected children, those whose parents agreed to participate in the research were invited to come, to the Department of Orthodontics of the Faculty of Dentistry Pančevo.Intraoral inspec tion, study models analysis and analysis of the panoramic and lateral cephalograms were con ducted on 88 subjects.
The study conformed to the Declaration of Helsinki.It was approved by the Ethics Com mittee of the Faculty.All the participants were recruited on the voluntary base, and their par ents were asked to sign an informed consent form, since the participants were under 18 years of age.
All lateral cephalograms were made at the Faculty of Dentistry Pancevo.All lateral cepha lograms were taken under the same conditions.Patients were positioned with their head in cephalostat and teeth in maximal intercuspation so that the Frankfurt's horizontal was parallel with the floor, and the middle sagital plane was parallel with the tape and the film.The distances between the focus and the mediosagital plane of the patients and between the mediosagital plane

ke analize
Statistička analiza urađena je korišćenjem SPSS statističkog softvera (SPSS for Windows, release 15.0, SPSS, and Chicago, IL).Deskrip tivna statistika (srednja vrednost, standardna and the film were the same for each patient.Lateral cephalograms were analyzed with clas sis approach on acetate paper and based on the cephalometric points by the two orthodontists.The identified landmarks, angular and linear measurements are presented in Figures 1 to 4.

Diskusija
U nekim studijama zapisi pojedinaca sa univerzitetskih klinika ili drugih institucija korišćeni su za određivanje kefalometrijskih standarda.U proces istraživanja bili su uključeni objektivni kriterijumi, kao što su klasifikacija po Anglu, pozitivan horizontalni i vertikalni mum and maximum) were conducted for all measured values.Descriptive statistics were presented as mean values with standard de viations for continuous variables.Categorical data were presented by absolute numbers with percentages.Differences between groups were compared with parametric Student's t test.In all tests, p value <0.05 was considered to be statis tically significant.

Results
Out of 88 subjects that were examined at the Department of Orthodontics at the Faculty of Dentistry Pancevo, 78 children were selected (42 girls mean aged 9±0,43 years and 36 boys mean age 9±0,17 years), 10 children were ex cluded from the study due to the following rea sons: lateral cephalograms of 3 boys and 2 girls were of poor quality and 5 children are current ly under orthodontic treatment.
Results of the cephalometric analysis are presented in Table 1.Inter-gender comparison showed that girls and boys in this age group sig nificantly differ in measured values.Linear mea surements such as Sella-nasion length (p<0.05),corpus maxilla (p<0.05) and anterior facial height -Nme (p<0.05) are more significant in boys as well as the angle which represents the position of the mandible toward anterior cranial base (SN/mP, p<0.05).).It was found that the ratio of the anterior to the posterior facial height points to statistically significant difference be tween girls and boys (SGo/Nme x 100, p<0.05), as well as the angular parameters; SNA -the angle of maxilar prognathism (p<0.05), and SNB -the angle of mandibular prognathism (p< 0.05).Remaining linear and angular parameters are of similar values which indicates that there are no statistical significant differences.

Method Error
Errors of measurements were calculated based on Cronbah alpha coefficient which measures the reliability between two examiners and vary from 0.702 to 0.813 for measured variables. 5,6
Naš nalaz pokazuje da je dužina korpusa maksile veća kod devojčica nago kod dečaka.maksilarni prognatizam, koji označava ugao SNA, takođe se razlikuje među polovima.mak sila je kod devojčica više protrudirana nego kod dečaka, ugao SNA je veći za 2.24° i postoji statistički značajna razlika (p<0.05).Slične re zultate imali su Barbara Obloj i saradnici 10 , ali classification, positive overjet and overbite, lack of crossbite, and lack of bucal and oral failure were included in the research process, and the only subjective criteria was the good facial proportion.Ethnical homogeneity was achieved through the selection of samples that were of the same national origin.Even though the environment in question is multiethnic, all children were of Serbian nationality.

Comparison among genders
In our country similar study has been per formed by Stošić et al 7 in profile cephalometric analysis in patients with class II division 2 mal occlusion.
Only several parameters did not show dif ferences between genders in this age group.The length of anterior cranial base (Sella-nasi on) was found to be more significant in boys than in girls.There is statically significant dif ference of p<0.05, which is in accord with the results obtained by the Ursi et al. 8 who exam ined 23 male and 28 female subjects aged from 6 to 18. Similar results were obtained by Bhatia and Leighton 9 who found the significant differ ence in genders aged 4 to 20 as well as by Obloj et al. 10 who found that there is greater length of anterior cranial base in Polish boys.
Anterior facial height shows significant dif ferences among genders, such as the greater height in boys of 1.25 mm than in girls (there is statistically significant difference p<0.05), while the posterior facial height is greater in girls by 0.44 mm, but without statistically sig nificant difference, p>0.05).Similar result for the anterior facial height was obtained by Obloj et al. 10 .This supports the results of Drevensek et al. who examined 42 boys and 46 girls with ideal occlusion aged 9.31 on average (SD=1.52)and found significant differences among gen ders 11 .
Additional parameters that we examined were corpus maxilla, corpus mandible, maxillar and mandiblar prognathism, gonial angle, re lationship of upper jaw toward anterior cranial base and lower toward anterior cranial base.Our findings show that the corpus maxilla is more developed in boys than in girls.maxilar prognathism which represents the SNA angle is also different among genders.maxilla in girls shows more protrusion than in boys, SNA angle is greater by 2.24° and there is also statistically significant difference (p<0.05).Similar find ings were obtained by Obloj et al. 10 however; se naši rezultati ne slažu sa rezultatima Ursi i saradnika 8 , koji nisu otkrili nikakvu razliku među polovima kod maksilarnog prognatizma.Takođe, naš nalaz se razlikuje i od El-Batouti i sar. 12 koji su pokazali da je kod norveškog sta novništva maksila više protrudirana kod dečaka nego kod devojčica.
• maksila i mandibula su više protrudira ne kod devojčica.our findings do not support the results of Ursi et al. 8 who did not find any difference among gen ders and with regards to maxillary prognathism.In addition, our findings differ from El-Batouti et al. 12 results which stated that the maxilla in Norwegian population shows greater protru sion in boys than in girls.The angle of man diblar prognathism (SNB) also shows the dif ference among genders such as greater angle in girls than in boys.The difference is 2.9° which shows that there is statistically significant differ ence p<0.05.The relationship between maxilla and mandible toward anterior cranial base (SN/ SPp and SN/mP) shows the difference.We de termined that the difference among genders ex ists in the relationship of mandible toward ante rior cranial base and that the angle is greater in boys.The difference is statistically significant, p<0.05, while in the angle SN/SPp there is no statistically significant difference p>0.05.Go nial angle shows similar values among genders.Comparisons of craniofacial structure among white populations are presented in Table 2.

Conclusion
• Nine-year-old boys differ from girls in several parameters: they have longer anterior cranial base, corpus maxillae, greater anterior facial height and greater slope of the lower jaw.
• maxilla and mandible show greater protrusion in girls.

Table 2 .
Comparison of craniofacial structure with other populations