Synthesis and characterization of -heterofunctional poly(ethylene oxide) macromonomers

Etilen oksidin (EO) anyonik yaşayan polimerizasyonu makromonomer sentezinde kullanıldı. Bu amaçla, metakriloil ve tienil uç grupları bulunan yeni bir a,w-heterofonksiyonel poli(etilen oksit) (PEO) makromonomeri halka-açılımı polimerizasyonu ile yüksek vakumda sentezlendi. Polimerizasyon potasyum tieniletoksit ile başlatıldı ve 40 0C’ de üç gün devam ettirildi. Yaşayan PEO zincir uçları metakriloil klorür (MAC) ile sonlandırıldı. Ayrıca, iki fonksiyonel gruba sahip olan makromonomerin serbest-radikal polimerizasyonu metakriloil, oksidatif polimerizasyonu ise tienil gruplarından gerçekleştirildi. Metakriloil ve tienil gruplarının varlığı, serbest-radikal ve oksidatif polimerizasyon yöntemleri, 1H-NMR analizi ve GPC ölçümleri yardımıyla aydınlatıldı.  Anahtar Kelimeler: Makromonomer, a, w-heterofonksiyonel polimerler, serbest-radikal polimerizasyon, oksidatif polimerizasyon.PEO macromonomers possessing thiophene moiety at one end and methacrylate group at the other end were prepared by a conventional high vacuum line technigue. A general method have been recently developed for synthesis of hetero-functional or hetero-telechelic PEO macromonomers by using a functional alcohol for initiating polymerization of EO followed by terminating with the other functionality. Using the same approach, a novel a,w-heterofunctional poly (ethylene oxide) macromonomer (PEO-makromonomer) possessing methacryloyl and thiophene end groups were prepared by ring-opening polymerization of ethylene oxide initiated by potassium thiophene ethoxide and termination of living ends of PEO with methacryloyl chloride. Polymerization was carried out at 40 0C over 3 nights. The obtained macromonomer has two polymerizable groups: the thiophene ring, with substitution at the 3-position, can be employed in oxidative polymerization while the vinyl group is useful for radical polymerization. The macromonomer, having an electroactive group, was polymerized oxidatively in the presence of FeCl3 as an oxidant. The macromonomer was also used in homopolymerization via vinylic terminus. The reaction involves the free radical polymerization of PEO in the presence AIBN as a thermal initiator. The evidence for successful free radical and oxidative polymerization processes was obtained by GPC measurements Incorparation of methacryloyl and thiophene groups were confirmed by 1H-NMR analysis, free radical and oxidative polymerization processes, respectively. Keywords: Macromonomer, a,w-heterofunctional polymers, free radical polymerization, oxidative polymerization

Cone-beam computed tomography evaluation of relationship between tongue volume and lower incisor irregularity

The aim of this study was to evaluate the relationship between the tongue volume and lower incisor irregularity, using cone-beam computed tomography (CBCT), and to identify the possible gender differences. CBCT images of 60 patients between 16 and 36 years of age were selected from 1400 sets of images in the database. Tomography was carried out using iCAT (R) (Imaging Sciences International, Hatfield, Pennsylvania, USA) and segmentation was carried out by using Mimics 10.1 software (Materialise NV, Leuven, Belgium). The tongue volume was calculated by using the volume of the voxels from the scan and the number of voxels selected for a given mask. Lower incisor crowding was measured with the Little's irregularity index and divided into three groups: mild, moderate, and severe. Independent samples t-test, analysis of variance (ANOVA), and Tukey test were used at P < 0.05 level. Pearson correlation coefficients and linear regression model were calculated to determine the correlation between tongue volume and incisor irregularity. No significant gender dimorphism was found for the tongue volume (females: 28.13 +/- 8.54 cm(3) and males: 31.02 +/- 9.75 cm(3)). According to ANOVA, there was statistically significant difference in the tongue volume measurements among subjects with different levels of irregularity. Tukey analysis indicated that mild irregularity group (33.97 cm(3)) showed higher values for tongue volume than severe irregularity group (26.60 cm(3); P = 0.025). The relationship between incisor irregularity and tongue volume was evaluated for both genders and significant inverse correlation (r = -0.429; P = 0.029) was determined between lower incisor irregularity and tongue volume in males. In female group, no signifi cant correlation was determined between tongue volume and incisor irregularity

Relation Betwen Tongue Dimensions and Lower Incisorr Crowding

Aim:The aim of this study was to evaluate the relationship between the tongue dimension measurements and lower incisor crowding/position and to identify the possible gender differences.Subjects and Method:Forty-five pretreatment plaster models and cephalometric radiographs of Class I patients taken by a standard technique formed the sample for this study. The sample of this study included 22 male (mean age: 15.67±1.41 years) and 23 female (mean age: 13.86±1.35 years) patients. Lower incisor crowding was measured with the Little irregularity index. Multivariate statistical analysis was used at p<0.05 level. To evaluate the correlation between tongue area and lower incisor crowding/position; Pearson correlation coefficients (r) were estimated.Results:Statistically significant gender differences were determined in tongue area (p=0.001). There was no statistically significant difference for the tongue measurements among subjects with different levels of crowding. In female group, significant correlations were determined between tongue area, L1-NB (mm) (r= 0.457; p=0.029) and L1-NB (⁰) (r= -0.447; p=0.032) measurements. In male group, significant correlations were determined between incisor crowding, L1-NB (mm) (r= -0.590; p=0.004), L1-NB (⁰) (r= -0.638; p=0.001) and L1-mandibular plane (⁰) (r= - 0.505; p=0.017).Conclusion:No relationship was found between tongue measurements and different levels of mandibular incisors crowding. Statistically significant correlation was found between tongue area and mandibular incisors position for both genders. Beside this, males showed significant inverse correlation between irregularity index and mandibular incisors position

Dehiscence and fenestration in skeletal Class I, II, and III malocclusions assessed with cone-beam computed tomography

Objective: To test the null hypothesis that the presence of dehiscence and fenestration was not different among patients with skeletal Class I, II, and III malocclusions

Dehiscence and fenestration in patients with different vertical growth patterns assessed with cone-beam computed tomography

Objective: To test the null hypothesis that the presence of alveolar defects (dehiscence and fenestration) was not different among patients with different vertical growth patterns