Orthodontic bracket adhesion involves multistep procedures which are technique sensitive to various factors within the oral environment. RelyX Unicem is a restorative/prosthodontic adhesive material which by virtue of its one step adhesion procedure may prove to be suitable for efficient orthodontic bonding. The objective of this study was to compare the SBS of RelyX Unicem with six other known orthodontic bonding materials. Seventy extracted human premolar teeth were divided into seven groups of 10 teeth each. On each group, metal orthodontic brackets were bonded using one of the seven bonding materials: (A) Transbond XT primer and Transbond XT luting cement (B) F2000 compomer primer/adhesive (C) Transbond Plus and Transbond XT luting cement (D) RelyX Unicem (E) Prime & Bond NT and Calibra cement (F) Xeno III and Calibra cement (G) NRC + Prime & Bond NT and Calibra cement. Shear bond strength evaluation of each tooth was tested and recorded using the Instron materials testing machine. The results show that the mean SBS for RelyX Unicem is 5.38 MPa and NRC is 4.70 MPa which rates weak compared to all the other materials where the means for the SBS are within the acceptable range of 5.9 to 7.8 MPa. It appears that by reducing the number steps followed for orthodontic bracket adhesion, the SBS of the orthodontic adhesive materials becomes significantly compromised to the extent where such materials can be rejected as suitable for orthodontic bracket adhesion. RelyX Unicem and NRC were found to be unsuitable for orthodontic bracket adhesion.
In orthodontics, evaluation of skeletal age and growth maturation is essential in diagnosis and treatment planning. The use of hand wrist radiographs perform this function adequately. However, it is not the only method, as the body of the third cervical vertebra (C3) also provides a similar information. It may be clearly discerned on the routine cephalogram, obviating additional radiation. This study sets out to present the various morphologic changes observed radiographically in the body of C3 at different age groups. The cephalograms of one hundred and sixty two patients (79 males and 83 females) were evaluated from the records at the Medunsa Orthodontic Department. The body of C3 was studied on each film according to the criteria set by Hassel & Farman. The results showed that radiographically, the body of C3 displayed morphological changes consistent with normal skeletal maturation that indicated the usefulness of this technique in clinical and research work. This method therefore shows promise as an alternative to hand wrist growth stage evaluation.
Flexure of the cranial base plays a crucial role in the study of the craniofacial complex.The outcome of orthodontic treatment can be predicted if growth and flexure of the cranial base is understood.The aim of this study was to determine the relationship between cranial base flexure and sagittal jaw relationships in a sample of Black South African subjects.A sample of pre-treatment lateral cephalograms of 300 patients with a mean age of 17.72 years was divided into three equal groups according to gender and skeletal classification.Age differences were tested using the Kruskal-Wallis test.Cranial base flexure differences were first tested using ANOVA and further evaluated using Student's t-test.Age distribution was similar in all three in all classes of sagittal jaw relationship.Class II subjects demonstrated a significantly larger cranial base flexure when compared with Class I and Class III subjects respectively.In this study sample, a larger cranial base flexure is a feature of Class II sagittal jaw relationship whilst both Class I and Class III sagittal jaw relationships are associated with smaller cranial base flexures.There were no significant differences between the Class I and Class III sagittal jaw relationship samples.Cranial base flexure, skeletal classification, sagittal jaw relationship.It has been hypothesized that the opening of CBF will displace the mandible more distally towards a Class II sagittal jaw relationship tendency whilst closing of CBF will displace the mandible more anteriorly towards a Class III sagittal jaw relationship. 4A study by Hopkin, Houston and James demonstrated that CBF increased significantly from skeletal Class III through Class I up to Class II subjects.
Orthodontic bracket adhesion involves multistep procedures which are technique sensitive to various factors within the oral environment. RelyX Unicem is a restorative/prosthodontic adhesive material which by virtue of its one step adhesion procedure may prove to be suitable for efficient orthodontic bonding. The objective of this study was to compare the SBS of RelyX Unicem with six other known orthodontic bonding materials. Seventy extracted human premolar teeth were divided into seven groups of 10 teeth each. On each group, metal orthodontic brackets were bonded using one of the seven bonding materials: (A) Transbond XT primer and Transbond XT luting cement (B) F2000 compomer primer/adhesive (C) Transbond Plus and Transbond XT luting cement (D) RelyX Unicem (E) Prime & Bond NT and Calibra cement (F) Xeno III and Calibra cement (G) NRC + Prime & Bond NT and Calibra cement. Shear bond strength evaluation of each tooth was tested and recorded using the Instron materials testing machine. The results show that the mean SBS for RelyX Unicem is 5.38 MPa and NRC is 4.70 MPa which rates weak compared to all the other materials where the means for the SBS are within the acceptable range of 5.9 to 7.8 MPa. It appears that by reducing the number steps followed for orthodontic bracket adhesion, the SBS of the orthodontic adhesive materials becomes significantly compromised to the extent where such materials can be rejected as suitable for orthodontic bracket adhesion. RelyX Unicem and NRC were found to be unsuitable for orthodontic bracket adhesion.
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