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Advances in the treatment of wedge defect filling

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发表于 2018-9-16 15:17:54 | 显示全部楼层 |阅读模式
Wedge-shaped defect is a common dental hard tissue disease, mainly occurring in the neck area of the tooth body, which can usually cause dentin sensitivity. Deep wedge-shaped defect may lead to pulp infection and even horizontal fracture of the tooth. At present, the clinical treatment of wedge-shaped defects is mainly the filling treatment of composite resin materials, which is prone to edge microleakage, dentin sensitivity, backfill shedding and secondary caries. This paper reviews the advances in the treatment of wedge-shaped defects.
1. Tooth preparation before filling
The box retainer or inverted concave retainer can be prepared properly before the wedge defect is filled, which can effectively improve the retention rate of the backfill. Sun Genzhu etc. Research shows that: the use of composite resin material for filling wedge-shaped defect before treatment, the defect of the champions league for the gum and cant prepare depth reach dentine shallow box shape retention, and appropriately increase concave, compared with no preparation, can improve the success rate of repair of filling body, compared statistically difference between groups; At the same time, the tooth filling body of the box retainer group has better edge densification, which may be related to the relatively large thickness of filling material at the edge of the box cavity group.
1.1 effects of hardened dentin
The dentin of teeth with wedge-shaped defect is stimulated by chronic external factors such as acid erosion and mechanical wear for a long time, and the dentin cells inside the dentin tubules become denatured, causing mineral salt deposition and sealing the dentin tubules, leading to the formation of hardened dentin. The unique structure of dentinal tubules blocked by mineralization will prevent the formation of resin protrusions, thus affecting the bonding effect of acid corrosion. Therefore, the surface pretreatment of wedge defect is very important.
Some scholars believe that the use of grinding to remove the hardened dentin will damage more dental tissues and normal dental structures, and easily cause sensitive discomfort in patients. EDTA (ethylene diamine tetraacetic acid), as an organic compound that can chelate calcium ions, can effectively remove calcium salt deposited crystals in the dentinal tubule of hardened dentin, improve the acid-etching binding effect, and do not damage the normal dentin structure, so as to avoid causing patients' sensitivity after surgery. Superfine morphological study showed that the acid corrosion or corrosion from acid can effectively dissolve sclerotic dentin calcium salt deposition crystals of small tube joint using EDTA (preprocessing to remove deposition crystal) and acid corrosion system (bonding surface acid corrosion demineralization of processing) bad can effectively improve the sclerotic dentin bonding surface, which increases the binding effect of filling body.
1.2 application of laser holes
A large number of studies suggest that the use of Er, Cr: YSGG laser irradiation can significantly increase the surface roughness of dentin and thereby increase the bonding strength. Sung et al. showed that using Er, Cr: YSGG laser to prepare dentin could achieve the same effect of acid etching and bonding as the traditional preparation method. Research by liu yan et al. shows that Er, Cr: YSGG laser can increase the shear bond strength between the dental body and the filling body after the non-carious hardening dentine of the elderly, which is higher than that of the high-speed turbophone preparation, especially suitable for the composite resin filling. In addition, compared with the preparation of traditional turbophones, the laser preparation process does not have adverse factors such as noise and vibration during the grinding process, which is especially suitable for sensitive patients and some elderly patients with extensive wedge defect.
The gingival wall of wedge-shaped defect often reaches the subgingival and is accompanied by caries. The treatment effect is affected by the large amount of gingival crevicular fluid and blood pollution during the preparation or filling process. Therefore, the treatment of gingival is very important. The methods of gingival removal include: gingival line method, gingival plaster method, gingival push method, laser gingival cutting method, etc. Currently, the most commonly used method in clinical practice is the gingival line method.
2. Use of binders
At present, the most widely used binders for filling wedge defects are self-etch binders and all-etch binders. The whole acid-etching bonding system mainly makes the surface of tooth demineralization form interstitial honeycomb structure through acid-etching, and the adhesive infiltrates into the interstitial space to form micro-mechanical intercalation between the dental tissue, and then completes the bonding between the resin and the dental tissue through the double-bond polymerization between the binder and the resin. The self-etching bonding system is mainly achieved by forming ionic bonds between the acidic monomer in the binder and the calcium ions in the hydroxyapatite crystals in the dental tissue.
2.1 comparison of self-etching and all-etching bonding systems
In recent years, the technology of oral adhesion has been rapidly updated and many reliable adhesion systems have been used in clinical practice. Tian fucong et al. compared the efficacy of Tetric n-bond self-etch system and total etch system Tetric n-bond system for filling wedge-shaped defects with mixed fillers and resins. Zhang Ran compare the sixth generation since the acid corrosion bond system such as Xeno Ⅲ and fifth generation full acid etch bond system Prime&Bond NT effect in treating wedge-shaped defect filling results show that both has good clinical efficacy in 1 year.
2.2 effect of etching time
For the whole acid etching system, some scholars believe that appropriate increase of acid etching time can increase the demineralization degree of hardened dentin surface and thus improve the bonding effect. As for self-etching binders, some studies suggest that preetching can improve the bonding effect between partially self-etching binders and hardened dentin. Liu ke music, corrosion from acid and total acid corrosion is studied in two kinds of binder system with 35% phosphoric acid pretreatment effect on bond strength of different time, the results showed for the acid corrosion system, phosphate pre-treatment 30 s group of the bond strength significantly greater than 15 s, adhesive and phosphoric acid pretreatment before 15 s or increase the adhesive coating can effectively increase the acid corrosion of adhesive bond strength. For hardened dentin, due to the high mineralization in and around the dentin tubules, 15s of acid-etching time cannot make it completely demineralized. However, after 30-s of acid-etching, the dentin demineralization degree increases, forming a thicker mixed layer and a longer resin protrusion, so as to enhance the bonding strength.
2.3 effects of adhesion system on postoperative susceptibility to filling
In terms of postoperative sensitivity to fillings, li yumei's study shows that the self-etching bonding system can effectively reduce the sensitivity of wedge defect after filling in a short period of time (7d). The results of zhu guilian's study also showed that the clinical and postoperative sensitivity of the whole acid-etched adhesive system was significantly higher than that of the self-etched adhesive system. This may be related to the bonding mechanism is different, the acid etch bond system in the process of binding, it is difficult to control a fully formed between binder with tooth chimeric micro machine, especially the dentin after acid corrosion, the fluffy status, excessive drying or excessive wet processing of the tooth surface, all can cause micro leakage, small tube of dentin fluid imbalance, causing postoperative dentine hypersensitivity.
Since the acid etch bond system in the bonding process, from the weak acid ingredients dissolved in acid etch bond system dentine polluted layer, and bonding resin monomer in the system composition and dentine collagen fiber blend, the formation of mixed layer, the mixed layer can have the effect of pipe plug, balance of dentine small tube of fluid, thus effectively reduce the wedge-shaped defect postoperative condition of dentine hypersensitivity.
3. Selection of filling materials
At present, glass ions and composite resin materials are mainly used for filling wedge defect. Which the thermal expansion coefficient of glass ion materials and tooth hard tissue close to the body, and it is in the form of chemical combination, with the hard tissues reliably, bonding and less irritating on the dental pulp, and glass ion material in the mouth can release fluoride ion for a long time, improve the fluorine content of hard tissues, so as to improve the resistance of dental caries. However, the glass ionic material has poor wear resistance. The composite resin material has good aesthetics and wear resistance, but due to its polymerization shrinkage, it is easy to cause microleakage at the edge of the filling body and shedding after filling, and the resin material has certain irritation to the pulp. Sandwich technology takes glass ions as the base material and utilizes the chemical bond between them and dentin to fill the defect part of dentin in the cavity, and then resins are used to fill the surface part of the cavity through acid etching. This method can not only avoid the stimulation of composite resin on dental pulp tissue, but also avoid the disadvantages of low hardness and poor wear resistance of glass ionic materials.
Previous clinical studies have also shown that sandwich technique for filling wedge defects has good clinical efficacy in preventing postoperative sensitivity, reducing the fracture rate of the backfill and maintaining the integrity of the backfill. The flow resin is a kind of fluidity composite resin material, compared with the general composite resin material, its wettability is better, can better fit with the fovea wall, and can enter the small and narrow area in the fovea cavity and fully close with the tooth structure, reduce the bubble formation. The study of Chen qian et al. showed that flow resins filled with wedge defects were more effective than traditional composite resins in preventing backfill shedding and secondary caries. However, in order to guarantee the good fluidity of the flow resin, the content of the inorganic filler is less than that of the composite resin, so the elastic modulus and strength of the flow resin after curing are lower. Based on this, it is proposed that the mobile resin is used for lining the bottom of the cavity, and then composite resin is used to fill the surface of the cavity.
Chen Ming et al. showed that the use of flow resin lined cavity bottom, combined with composite resin filling, compared with chemically cured glass ions or simple composite resin filling, can obtain smaller micro-leakage and closer bonding between teeth, and has more ideal edge sealing. The research of zhang yao et al. also showed that the photocurable flow resin lining and composite resin filling wedge defects had a relatively higher success rate. However, on the other hand, due to the different flow of resin and composite resin materials, packing type, content also have their own internal differences, so in the process of two kinds of resin curing, volume shrinkage of interface stress also has difference, two kinds of resin in the curing process at the same time, due to the component, in combination with the interface can form a variety of polymer chain, these factors could lead to a junction between the tensile strength decreased.
The mechanical experiments of xu hai et al. showed that the micro-tensile strength of the interface between the general type Z350 resin and the flow type F350 resin was significantly lower than that of the same resin, which is worthy of attention of clinicians. The development of materials has led to more new resins that can be used to fill wedge defects. The full-layer filling flow resin SureFilSDR flow resin retains the advantages of good fluidity and low elastic modulus of the flow resin, and at the same time, a kind of photoactive group is added to it, which enables it to fill and solidify in a deeper layer. The composition of polyurethane dimethacrylate, which can adjust the polymerization rate, can slow down the curing speed of the resin, thus reducing the shrinkage stress in the curing process and reducing the strain tension between the resin and the cavity wall.
Clinical studies have shown that the single-curing deep wedge defect filling with the whole layer of flow resin can achieve the same clinical effect as the traditional laminated resin filling. Wedge defect is a high C factor hole, and the filling material has a greater cohesive shrinkage, and the possibility of filling failure is also increased. Low polymerization shrinkage of resin FiltekTMP90 siloxane and cyclohexene oxide by reaction of siloxane compounds as the substrate, polymerization shrinkage rate lower than 1%, and the traditional, polymerization shrinkage of the larger methyl acrylate polymer material is different, in the form of long chain crosslinking curing skeleton ring polymer chain is contained in the matrix, aggregate curing ring at the long chain will open and smaller by the crosslinking polymerization shrinkage.
According to zhang yao et al., using FiltekTMP90 low-shrinkage resins to fill wedge defects can achieve good clinical results in many aspects, such as success rate, retention, edge coloring, edge densification, surface morphology and color coordination.
4. Post-filling treatment
After the wedge defect filling treatment, the polishing of the filling body is related to aesthetics, service life and marginal microleakage. The traditional emery polishing, due to the larger size of the polishing drill, is easy to cause microcracks on the surface of the backfill, which also increases the possibility of the adjacent tooth tissue abrasion. The ufos-lexdiscs polishing system and Supersnap polishing system contain relatively fine particles, the smallest being 5 ~ 10 sheets m, and the main ingredient is aluminum oxide with high hardness, which is obviously higher than silica and the filler used by most composite resins. During polishing, the resin matrix and inorganic filler can be removed synchronously, resulting in smooth surface. Studies have shown that specimens polished by the Supersnap polishing system show less scratches and pits under electron microscopy, resulting in a smoother surface.
His research showed that compared with emery polishing, composite resin microleakage depth polished by sme-lexdiscs polishing system and Supersnap polishing system was smaller, and the two had statistical differences. The study by ren qiang et al. showed that after filling the wedge defect composite resin, it can be polished by the Sof-lexdiscs and Supersnap polishing system, which can reduce the occurrence of postoperative secondary, edge coloring and abrasion, and maintain the edge sealing of the resin. Occlusion is one of the causes of wedge defect. It can be inferred from this that the treatment of wedge defect is only treated by filling, but not effectively removing the cause. The continued existence of pathogenic factors will inevitably affect the treatment effect.
Through occlusal adjustment, the lateral force of the dental body is reduced, and the stress of the filling material and its adjacent dental tissue is alleviated under the functional state. Therefore, the related occlusion adjustment is necessary after the filling treatment. Wang ping et al. showed that the successful rate of filling repair can be improved by adopting the method of occlusal adaptation before the cure of wedge defect and the method of dental adjustment after filling.
5. Summary
At present, composite resin filling is the most commonly used method to treat wedge defect. The successful treatment is based on perfect tooth preparation, surface treatment and gingiva. With the development of materials science, choosing suitable adhesive materials and filling materials can effectively prevent backfill shedding, pulp sensitivity and edge microleakage, etc. After the filling, the filling body polishing and proper occlusion adjustment are also important to the success of treatment. All the above steps in the treatment process are worthy of full attention by stomatologists.

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