A Study In Vitro On Quality Of 3 Adhesives

OBJECTIVEThe approach of direct bonding is popular in orthodontic clinic. It has several advantage: it minimize soft - tissue irritation, makes patients more comfortable, enhances the patient's ability to remove plaque, eliminates the pain of pretreatment separation, decreases chair - side time and appears more esthetic for the patient. But clinical improvements related to orthodontic bonding are still needed in some areas - reduction of white spot lesions on the enamel surface, prevention of cracking on enamel during debonding and decrease of the incidence of bond failure etc. The purpose of this study was to compare the shear bond strength of three resin adhesives: Jingjin enamel adhesive(JJ) , single-component adhesive(SC) and Superbond C&B system (SB) when bonded the brackets to enamel with them under the various situations: bonded routinely, sandblasting the bracket before bonding, artificial saliva contamination on the etched enamel, compare the ARI( adhesive remnant index) on enamel after debonding among 10 test groups , record the enamel cracking of every group .METHODSOne hundred and fifty premolars that had been extracted for orthodontic purpose were collected from patients. All teeth were stored in 0. 5% aqueous chloramines T for a maximum of 6 months beforetesting. The teeth were then randomly assigned to 10 equal groups, 15 teeth for each group.The brackets tested were Edgewise metal brackets ( Hangzhou, Xinya) with a cross - section 0.022+0. 028 inch and with a base area 11. 84mm2. The brackets were bonded to the teeth according to one of following ten protocols:I.JJIa. Bonded routinely. Brackets bonding to the 15 teeth according to the directions of the manufacture.I b . Sandblasting group. Before bonding 15 brackets were sandblasted 5 seconds, then bonded immediately according to the manufactured direction.I c . Saliva contamination and dried. Artificial saliva contaminating on the etched enamel, dried, then bonded as group I a .I d . Saliva contamination and kept moisture. Artificial saliva contaminating on the etched enamel, kept moisture, then bonded as group I a .II.SBII a . Bonded routinely. 15 brackets bonding to the 15 teeth with Superbond C&B according to the manufactures directions.II b . Saliva contamination and kept moisture. Artificial saliva contaminating on the etched enamel, kept moisture, then bonded as group Ha .III.SCIIIa. Bonded routinely. Bonded the 15 brackets to 15 teeth buc-cal surface according the directions of the manufacture.IIIb. Sandblasting group. Sandblasting the bracket's base 5S, then bonded immediately, and the last procedure was the same asgroup IIIa .IIIc . Saliva contamination and dried. Artificial saliva contaminating on the etched enamel, dried, then bonded as group IIIa .IIId . Saliva contamination and kept moisture. Artificial saliva contaminating on the etched enamel, kept moisture, then bonded as group IIIa .Each specimen was mounted vertically in self-care acrylic so that the shear force was parallel to each other. All groups were subjected to thermal cycling before debonding test. Thermal cycling was done with 1200 repetitions between 0 C&55 C. with a 30S dwell time in each bath. A Hydropuls testing machine ( Shimadzu Corporation, Japan) was used to test the shear bond strength. Recorded the shear force values of each specimen when the brackets were debonded. The shear bond strength per unit area was determined by dividing the individual values by the unit area of the bracket base. Shear bond strength was recorded in megapascals (Mpa).Following debonding, all teeth were examined under an optical stereomicroscope (7) . The amount of residual adhesive was classified with the adhesive remnant index (ARI) , which consists of a 4-point scale with score ranging from 0 to 3. A score of 0 indicates that no adhesive is left on the tooth, A score of 1 indicates that less than half the adhesive is left on the tooth, A score of 2 indicates that more than half the adhesive is left on the...