Comparative Evaluation of varying Photo-polymerization Time on Shear Bond Strength and Microleakage of Four Orthodontic Adhesives: An in vitro Study

Introduction High early bond strength, extended working time for optimal bracket placement, and easy cleanup of excess adhesive are few advantages of visible light-cure orthodontic adhesives. However, the shorter duration of polymerization may lead to polymer shrinkage and eventually microleakage. Objective To observe and evaluate shear bond strength (SBS) and microleakage of orthodontic brackets bonded to enamel with four commercially available orthodontic adhesives, cured only from incisal direction at various polymerization times. Materials and methods A total of 160 bovine incisors were randomly assigned to four groups according to adhesive used. Group I: bonded with Transbond XT (3M Unitek™, USA); group II: Enlight (Ormco, USA); group III: Light Bond (Reliance Ortho, USA); and group IV: Discover (Prime Dental, USA). Each group was further divided into four subgroups of A, B, C, and D according to the polymerization duration of 5, 10, 15, and 20 seconds respectively. The bonded teeth were immersed in dye solution. Brackets were then subjected to SBS test on a Universal testing machine. Surface microleakage was observed with the help of optical stereomicroscope. Results The SBS was obtained within the range of clinically accepted values, with curing time for Enlight at 5 seconds, Transbond XT and Discover at 15 seconds, and Light Bond at 20 seconds. However, Enlight was demonstrated to provide optimum SBS at least curing time: Minimum duration of 5 seconds achieved adequate SBS ~11 MPa SBS for each of Transbond XT and Enlight. The surface microleakage observed is statistically insignificant among the groups. Conclusion From a clinical perspective, a composite resin that needs minimum curing time without compromising on the bond strength is most advantageous. The results for SBS tests showed a better performance for Enlight as compared with the other adhesives: it reached its bond strength of optimum value at curing time of 5 seconds. How to cite this article Zanke PN, Patni V, Maskarenj M. Comparative Evaluation of varying Photo-polymerization Time on Shear Bond Strength and Microleakage of Four Orthodontic Adhesives: An in vitro Study. J Contemp Dent 2017;7(3):156-160

Sella Turcica: An Important Aid in Diagnosis and Treatment Planning

The purpose of this study was to describe and measure the size of sella turcica in subjects with different skeletal types. Lateral cephalometric radiographs of 120 individuals (60 males and 60 females) with an age range of 11 to 26 years were taken and distributed according to skeletal classification: 40 class I (ANB: 20–40), 40 class II (ANB: >40), and 40 class III (ANB: <20). The sella turcica on each radiograph was analyzed and measured to determine the linear dimensions of length, depth, and diameter. Student's t-test was used to calculate differences in linear dimensions, while a one-way analysis of variance was performed to study the relationship between skeletal type and sella size. No significant differences in linear dimensions between genders could be found. When age was evaluated, significant differences were found between the older (15 years or more) and the younger (11–14 years) age groups at the 0.01 and 0.001 levels for length, depth, and diameter. Sella size of the older age group was larger than in the younger age group. When skeletal type was compared with sella size, a significant difference was found in the diameter of sella between the classes II and III subjects (p < 0.01). Larger diameter values were present in the skeletal class III subjects, while smaller diameter sizes were apparent in class II subjects (multiple comparison tests). When gender, age, and skeletal type were all compared with the size of the sella (regression analyses), age was significantly related to a change of length (p < 0.01) and diameter (p < 0.001). How to cite this article Zanke PN, Patni V, Sonawane M, Karandikar G, Ravindranath VK, Maskarenj M. Sella Turcica: An Important Aid in Diagnosis and Treatment Planning. J Contemp Dent 2016;6(3):181-183