Composite resin direct aesthetic repair procedure (1)
C. Direct aesthetic repair of composite resin - acid etching and bonding
The cavity wall of the cavity consists of enamel and dentin. The composition proportion of the cavity enamel dentin boundary in different parts is different. The adhesive should be selected correctly according to the actual situation. Here are several commonly used methods of using acid etching adhesive.
1. Use of enamel adhesive
Dip a small cotton ball or brush with 15% - 40% orthophosphoric acid for 15-60 seconds, pay attention to uniform coating, strictly limit the scope of acid etching, do not apply it to dentin, surrounding soft tissue and tooth tissue beyond the bonding surface, so as to avoid demineralization of healthy tooth tissue and post-operative sensitivity of teeth. Then wash with high-pressure water of air gun for 10-40 seconds to remove the acid etchant and demineralisation. In clinic, it is forbidden to wash mouth by patients themselves to avoid saliva contamination. Clean and dry gas shall be used for moisture separation and drying, and the air flow direction shall be changed and adjusted to ensure the drying of each depression. After drying, the enamel surface lost luster and was chalky. Then coating the adhesive. Dip a small brush or sponge into the adhesive and evenly coat it on the acid etched tooth surface. Blow it evenly with clean soft wind for 20 seconds. Before coating, it is better to separate the affected teeth from the adjacent teeth with the molding sheet to avoid adhesion, and at the same time, pay attention to avoid the accumulation of resin binder in the molding sheet.
2. Use of dentin adhesives - use of total etching dentin adhesives
With a small brush dipped in more than 30% of high concentration phosphoric acid, it is first applied to enamel, then to dentin. Generally, the etching time of dentin is less than 15 seconds (operate according to the instructions of different products). The high pressure water washing time should be greater than or equal to the acid etching time. Dry the teeth with clean air from light to medium strength, and remove the excess water from the dentin at the bottom of the hole to the enamel at the edge of the hole. Cotton ball or absorbent paper can also be used to dip gently, so that the dentin surface presents a slightly smooth wet surface, and the enamel is relatively dry. After the primer is applied, it should be kept still for 20 seconds, so that the organic solvent of the primer can replace the water in the dentin, and guide the hydrophilic monomer of the primer to penetrate into the demineralized dentin collagen fiber network structure. At this time, the excess water in the tooth surface should be slightly dried. Then coating resin binder, uniform, comprehensive, about thickness. It is in the form of thin reflective film. The time of illumination shall also be light cured according to the time specified in the instructions. The binder shall be light cured completely to form a good mixing layer.
3. Dentin binder - the use of self etching binder
Operation diagram of the 6th generation bonding system of Guchi plastics
The two-step self etching adhesive consists of two components, dentin treatment agent and resin adhesive. Dentin treatment agent is a combination of etchant and primer. It should be applied under pressure for 20 seconds without water washing. Blow dry with clean air of weak to medium strength. The use of binder is the same as that of total acid etching dentin binder, but the illumination time is generally 10 seconds. In one step, self etching adhesive combines dentin treatment agent and resin adhesive into one bottle, pressure coating for 20 seconds, and light exposure for 10 seconds after blowing.
Some scholars think that the self etching adhesive bonding to enamel is not accurate and may have micro leakage. It is suggested that phosphoric acid should be used to etch the enamel first, and then self etching adhesive should be used in the routine.
After the tooth surface treatment, the forming sheet and wedge shall be placed. The front teeth are generally fixed with a wedge with a polyester film forming sheet to avoid overhang. The posterior teeth are fixed with stainless steel forming sheets and forming clips. The wedge should be wedged with a little force to separate the affected teeth from the adjacent teeth by using the physiological mobility of the teeth, so as to eliminate the thickness of the molding sheet and restore the gingiva at the contact point by relying on the rebound of the adjacent teeth after the molding sheet is removed. (the molding sheet is usually placed before the acid etching and bonding to prevent the acid etching of adjacent teeth or adhesion with adjacent teeth)
To be continued~