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    Effects of thermocycling on the degree of cure of two lingual retainer composites
    (Japanese Soc Dental Materials Devices, 2010) Catalbas, Bulent; Uysal, Tancan; Nur, Metin; Demir, Abdullah; Gunduz, Beniz
    The aim of this study was to evaluate the effects of thermocycling on the degree of cure (DC) and water sorption behavior of two lingual retainer composites. A total of 50 composite specimens, 5 mm diameter and 2 mm height, were prepared using Light Cure Retainer (R) (LCR) (Reliance) and Transbond Lingual Retainer (R) (TLR) (3M Unitek). After 40-second curing with a halogen light and after 24-hour water storage, the composite specimens were subjected to different thermocycling regimes. Absorbance peaks to monitor the DC were recorded using Fourier transform infrared (FTIR) spectroscopy, while water sorption was calculated in mu g/mm(3). On DC, significant differences among the different thermocycling regimes were observed only for the TLR specimens (p<0.05). On water sorption behavior, an increase in the number of thermal cycles resulted in increased water sorption for both composites, but the statistical differences in these groups were not significant. On the effect of thermocycling up to 20,000 cycles, present findings showed that LCR was less affected than TLR. Further, LCR exhibited higher DC and lower water sorption values than TLR after thermal cycling.
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    Effects of Transillumination Method on Bond Strenght of an Orthodontic Adhesive
    (Aves Press Ltd, 2007) Catalbas, Bulent; Gelgor, I. Erhan; Nur, Metin; Demir, Abdullah
    The purpose of this study was to determine the effect of transiluminasyon on the bond strength of orthodontic brackets. One hundred human maxillary premolars were used in this study. Brackets with orthodontic composite adhesive were placed on the labial surface of the premolars and light cured from either the labial and/or the lingual (transiluminasyon). The control sample was cured from the labial for a total of 40 seconds of light exposure. Experimental samples were cured from the buccal for 20 seconds, the lingual (transiluminasyon) for 20 or 40 seconds and both buccal and lingual for 40 seconds. The shear-peel bond strengths were tested at 24 hours after light application. The results of this study demonstrated statistically significant difference between 40 seconds of labial curing, the both buccal and lingual curing and the only lingually cured groups. Actual bond strengths were lower for only lingually cured samples but higher for the both buccal and lingual cued sles. The samples tested received 20 seconds of labially cured were nearly the same as the control values. This study demonstrated that transiluminasyon of maxillary premolars is not alone an acceptable method of cunng orthodontic adhesive. However, the bond strengths can be higher when the transiluminasyon is used in addition to the buccal curing particularly if the exposure time is inceased to 40 seconds.
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    Maxillary and mandibular mesiodistal tooth sizes among different malocclusions in a sample of the Turkish population
    (Oxford Univ Press, 2011) Malkoc, Siddik; Basciftci, Faruk Ayhan; Nur, Metin; Catalbas, Bulent
    The purpose of this study was to establish normative data for mesiodistal tooth crown dimensions with respect to malocclusions and gender differences in Turkish sample. The subjects were randomly selected and assigned to three malocclusion groups according to Angle's classification. Each group consisted of 100 individuals between the ages of 13 and 18 years with the following distribution: Class I, 42 males and 58 females; Class II, 52 males and 48 females; and Class III, 51 males and 49 females. An electronic digital calliper was used to measure the mesiodistal tooth width from the right second permanent molar to the left second permanent molar on both upper and lower study casts. For statistical evaluation, one-and two-way analyses of variance and post hoc Tukey's honestly significant difference (HSD) tests were performed. There were statistically significant differences for the maxillary canine (P < 0.001), first premolar (P < 0.05), second molar (P < 0.05), and mandibular canine (P < 0.01) for males, and for all maxillary teeth and the mandibular central (P < 0.05), canine (P < 0.001), and first premolar (P < 0.05) teeth in females among the malocclusion groups. When Angle's classification was evaluated, significant differences were determined, except for the first and second mandibular molars. All mesiodistal widths were also found to be statistically different according to gender dimorphism. A significant relationship was found between mesiodistal tooth size, Angle's classification, and gender. Therefore, tooth dimensions may play a crucial role in treatment planning and in achieving satisfactory interdigitation of the upper and lower dentition following the completion of orthodontic treatment.