Assessment of shear and tensile bond and rebond strengths of orthodontic brackets using different etching times

This in vitro study is designed to assess and compare the shear and tensile strengths of both bond and rebond strengths of adhesive with the metal brackets when they exposed to different etching times. Sixty sound upper first premolars had been extracted from 13-18 years old orthodontic patients, were divided into two groups, one group was tested for shear bone strength, and the other was tested for tensile bond strength. A new metal brackets were bonded to the buccal surface of the teeth using the same type of adhesive material, each group was subdivided into three subgroups and then etched with 37% phosphoric acid using 15, 60 and 120 seconds for etching, then the results were recorded for shear and tensile bond strengths for the sample. All the brackets were later on debonded and the brackets base with the remnant adhesive material were etched and rebonded to the teeth which were cleaned and prepared to receive etching solution using the previous etching times, then they were tested for the shear and tensile strengths. The results showed that there was a significant regression in the shear and tensile strengths of the rebonded orthodontic brackets than that of the bonded one, and the highest bond and rebond strengths were obtained at the 60 second etching time

study of lower arch crowding in relation to periodontal disease

A clinical examination was done to study the relationship between crowding and periodontal health status in the lower anterior region. The occurrence of the crowding was recorded in fifty adult male with Class I angle occlusal relationship who have not been received orthodontic treatment before. The sample was divided into two groups: a crowded group of 25 male presented with crowding in lower anterior teeth, and a normal group of 25 male presented with normal occlusal features and with no crowding. Scaling [supragingival and subgingival debridement] and polishing were done as required, plaque and gingival indices were scored before treatment, and then re-scored one, two, three and four weeks after treatment. It was found that the gingival index and plaque index are reduced in their value in a normal group while the gingival and plaque indices tend to return to their original pretreatment value in group of crowded lower anterior teeth and much faster than that of a normal group

Spacing in the normal deciduous dentition among urban and rural children in Baghdad province

In order to provide information about the deciduous dentition this study was designed to observe the pattern of spacing in the normal deciduous dentition and its correlation with the type of occlusion among children 3-6 years of age which were examined from urban and rural areas of Baghdad province, and the result showed that the spaced type of dental arch in the total sample were more common than the closed type or " no space" type, this was more prominent in both upper and lower arches more than its occurrence in a single arch, and was mostly associated with Class I sagittal Canine relation, this pattern was affected urban children, while, the spaced and the closed type dentition distributed similarly among rural children and the Class I sagittal canine relation was observed to be associated commonly with the closed type, on the other hand, it was found that the presence of the anthropoid space in the deciduous dentition was more common than its absence, with its higher frequency in the upper arch, and was similarly affected children in both urban and rural areas

relationship between the morphology of the first cervical vertebra and the direction of mandibular rotation in Iraqi adults

This study was performed to assess the relationship of the morphology of the first cervical vertebra [atlas] with the direction of mandibular growth rotation. The sample included 200 lateral cephalometric radiographs [81 males and 119 females] of Iraqi18- 25 year old pretreatment orthodontic patients. Tracing was done for all of these cephalometric films, 3 linear measurements for the atlas and 6 angular measurements, these measurements were done by using special analyzing software program [Auto Cad] program. The results showed that atlas dorsal arch and atlas length had significant correlation with mandiular growth rotation, the higher the dorsal arch and the longer the atlas is the more the horizontal rotation of the mandible, It was found that the effect of the sum of posterior angles during mandibular growth rotation is due to the change in the gonial angle rather than the saddle and articular angles. It is concluded that the morphology of atlas can be regarded as a predictor for mandibular rotation