Enamel leukoplakia refers to chalky spots or plaques on the surface of enamel, which are clinically manifested as dull and chalky changes on the enamel surface, accompanied by roughness, and no obvious cavities, which are more common in early caries, mild fluorosis and orthodontic treatment of affected teeth.
Dental fluorosis, also known as dental fluorosis or enamel tooth, is caused by excessive fluoride intake that inhibits the formation of hydroxyapatite crystals during enamel development, resulting in incomplete enamel mineralization. Incomplete mineralization leads to a chalky appearance on the surface of dental fluorosis, and in severe cases, enamel defects, and easy pigmentation to form, resulting in yellow-brown plaques on the tooth surface, which is a manifestation of endemic fluorosis.
Its damage to teeth is mainly manifested as changes in tooth color and morphology, which can be divided into three types according to its severity: mild (chalky), moderate (pigmented) and severe (defective), which seriously affects the quality of life and mental health of patients. In recent years, with the improvement of people's living standards and the improvement of drinking water quality, the incidence of endemic mass dental fluorosis has gradually decreased.
The occurrence of dental fluorosis is typical regional, and the incidence rate is higher in areas with rich mineral resources, which is generally distributed in villages or towns, which seriously affects the quality of life of people in the area.
With the continuous improvement of people's health awareness, the requirements for aesthetics are getting higher and higher, and the incidence of enamel leukoplakia in patients treated with orthodontics can reach 46%-73%, which not only seriously affects the aesthetics, but also increases the risk of caries. Nowadays, with the development of materials science, penetrating resin has shown good efficacy in the treatment of enamel leukoplakia, and the research progress of osmotic resin in the treatment of leukoplakia is reviewed.
1. Etiology and clinical manifestations of enamel leukoplakia
Normal enamel is translucent with a refractive index of 1.62, and enamel leukoplakia is enamel demineralization, which is manifested as chalky enamel plaques with dull surface and roughness.
The porous structure of the surface of enamel leukoplakia is conducive to the penetration of acids, bacteria or pigments into the deep enamel layer, which accelerates the progression of caries and causes pigmentation on the enamel surface, which also provides a physiological basis for the treatment of enamel leukoplakia.
2. Treatment of enamel leukoplakia
1. Bleaching treatment
In recent years, bleaching has been widely used in clinical practice as a non-invasive technique to improve tooth color. At present, the commonly used bleaching methods in clinical practice are mainly divided into office bleaching and home bleaching. Bleaching in the office is a type of bleaching that is performed in the office by a doctor with a higher concentration of bleaching agent under professional practice.
Due to the high concentration of bleaching in the clinic, it is required to isolate the soft tissue rubber dam in the mouth, and the effect can be seen immediately after bleaching, but there are shortcomings such as soft tissue burns, long chairside operation time, and tooth sensitivity.
The principle of cold light whitening is to increase the penetration ability of the whitening agent into the dentinal tubule through high-intensity blue light with a wavelength between 480-520 nanometers, so as to promote the oxidation of the pigment on the surface and deep layer of the whitening agent and fluorosis, and quickly achieve the bleaching effect. However, there are also clinical deficiencies, and some patients report that there is a sensitivity to tooth soreness during the treatment process.
Sodium hypochlorite bleaching is the oxidation and chlorination of pigments by sodium hypochlorite, so as to achieve the purpose of bleaching. Studies have shown that 5% sodium hypochlorite has a good bleaching effect on mild dental fluorosis, and can only slightly improve moderate and severe fluorosis.
In recent years, some scholars in China have proposed laser bleaching, which refers to the heat generation of a laser with a certain wavelength and energy, which enhances the bleaching agent applied to the tooth surface and accelerates the action speed, and it can selectively oxidize the pigment attached to the tooth, so as to achieve the effect of tooth whitening.
2. Microabrasion treatment
Micro abrasion is a minimally invasive treatment that is simple to operate and low cost, which can remove enamel plaque and achieve good clinical results.
Studies have shown that micro-grinding can remove 10-200pm of enamel, and the treated enamel surface is smooth, uniform in color and shiny.
Some scholars have found that micro-grinding has a better effect on the treatment of mild enamel leukoplakia, while for patients with severe vitiligo, it is recommended to use a combination of micro-abrasion and veneer repair, because micro-abrasion cannot completely remove the deep chalky plaques. Some scholars have also found that micro-grinding technology combined with bleaching technology can also achieve satisfactory treatment results for moderately to severely vitiligo teeth.
3. Restorative treatment
The minimally invasive treatment described above has a good therapeutic effect on mild and moderate enamel leukoplakia, but for patients with severe vitiligo, or when its aesthetic requirements are high, dental restoration can be considered. Examples include direct resin restoration, veneer or full crown restoration.
Full crown restoration materials include porcelain fused metal full crown and full porcelain crown, both of which require grinding off part of the enamel and dentin of natural teeth, which will cause irreversible damage to the pulp or risk of damaging the pulp, and the cost is relatively high.
Veneer restoration preserves more tooth tissue than full crown restoration, because it is in line with the concept of minimally invasive treatment, and has been highly respected in recent years, ultra-thin veneers came into being, its thickness is less than 0.5mm, the thinnest can be up to 0.2mm, it can reduce the amount of tooth preparation, or even no preparation at all.
4. Osmotic resin treatment
In recent years, some scholars have proposed the use of permeating resin for the treatment of enamel leukoplakia, which is a minimally invasive technique that can penetrate low-viscosity permeate resin into the porous enamel layer through the siphoning action of capillaries, and because the refractive index of this resin is similar to that of enamel, it can achieve a good whitening effect, and is recommended as the preferred treatment for the treatment of post-orthodontic enamel leukoplakia.
In recent years, it has also been used for whitening treatment of moderate to severe dental fluorosis, and has achieved good results. The study found that the refractive index of the enamel after the osmotic resin treatment was closer to that of healthy enamel and the aesthetic effect was better than that of bleaching.
3. The formation of the osmotic resin treatment system
1. Formation of penetrating resin
Resins can increase matrix content, reduce inorganic fillers to reduce viscosity, improve flowability, produce less surface tension, and penetrate diseased areas to reduce demineralization. At present, the penetrating resin commonly used in clinical practice is developed by foreign companies. Because of its good fluidity and high permeability coefficient, it is proposed for the treatment of dental fluorosis.
2. The principle of penetrating resin
(1) For early caries lesions in the oral cavity, the surface of early enamel caries was observed to be demineralized, and enamel crystals dissolved to form a porous structure, and white spots on the surface of enamel on the clinical surface were accompanied by pigmentation and enamel destruction.
Resin permeation technology allows the fluid resin material to penetrate deep into the pores of the demineralized enamel through the siphoning action of capillaries, sealing the channels for the invasion of acids, thereby preventing the progression of early caries.
(2) Scanning electron microscopy can be seen that a large number of honeycomb pores can be observed in the enamel layer of dental fluorosis, especially in moderate to severe dental fluorosis, which are filled with air, and there is a gap between its refractive index and enamel, so it will show a chalky appearance under the evaluation of natural light.
Since the refractive index of normal enamel is 1.65, the refractive index of water is 1.33, and the refractive index of air is 1.0, the refractive index of enamel depends on the size of the crystal space, during the early caries activity, with the beginning of the dissolution process of the surrounding crystals on the outer surface of the enamel, the dehydration phenomenon occurs between the crystals, and the water between the crystals is replaced with air, resulting in the appearance of white spots in the enamel.
The refractive index of the low-viscosity resin penetrating into the pores is 1.475, which is similar to the refractive index of normal enamel, and the treatment of chalk spots with penetrating resin can significantly reduce the appearance of chalk spots and meet the aesthetic requirements of patients.
3. Efficacy of penetrating resin
(1) Physical properties
In terms of surface roughness and microhardness of enamel after permeating resin treatment, the roughness of enamel surface after application of permeating resin was significantly lower than that of demineralized enamel. After thermal cycling of isolated premolars treated by different methods, it was found that the enamel surface of premolars treated with resin penetration was smoother, which was not conducive to bacterial adhesion and plaque formation, and the risk of early enamel caries damage was significantly reduced.
The permeable resin fills the intercrystalline pores formed by the demineralization of the enamel, and at the same time mixes with the remaining enamel column to form an enamel-permeate mixture, which restores the enamel morphology and thus improves the surface microhardness.
(2) Aesthetics
In cases of enamel leukoplakia, the penetrating resin is able to restore its normal enamel color. After demineralization, the enamel becomes porous, and the pores are filled with air, and because the refractive coefficient of air is lower than that of enamel, a chalky opaque area appears in the lesion area.
When the resin penetrates into the pores, the refractive coefficient is close to that of normal enamel, so that the color of the demineralization zone is close to that of normal enamel, and the aesthetics are improved. It was found that after the resin penetrated the enamel pores were filled, the chalky patches on the surface of the demineralized enamel disappeared because the refractive index of the permeated resin was close to that of the enamel, showing a relatively uniform aesthetic appearance.
- stability
and persistent dental fluorosis, in the late stage of enamel formation, the enamel hardness is lower than that of normal teeth. The pores of tooth enamel are mainly distributed in the outer 1/3 layer, which is easy to adsorb foreign pigments.
Some literature studies have found that the enamel surface of teeth after bleaching with hydrogen oxide or carbamide peroxide becomes irregular, the pores increase, the enamel is demineralized, the protein concentration decreases, and the degradation of organic matter is accompanied by a decrease in the proportion of calcium and phosphate.
This change makes it easier for tooth enamel to adsorb exogenous pigments, resulting in discoloration of the enamel. Some scholars believe that the surface treatment of bleached tooth enamel can reduce the staining of enamel and increase the durability of the bleaching effect, and in the clinical study of the chalk spots produced after orthodontic treatment, it has been shown that the chalk spots after osmotic resin treatment not only restore the beauty, but also have no obvious discoloration after surgery.
- Long-term efficacy
Although the permeating resin improved the microhardness and flatness of the demineralized enamel surface, some scholars found that the surface roughness of the enamel treated by permeating resin was significantly higher than that of the demineralization group.
The increase of roughness will accelerate the accumulation of plaque and the chance of tooth decay, so it is recommended that after resin penetration treatment, the excess resin on the enamel surface should be removed with a cotton roll before light curing, and the resin surface should be highly polished.
In addition, resin materials are susceptible to the influence of external and internal pigmentation over time due to the influence of various factors such as polymerization shrinkage, water absorption of materials, and polymer transformation degree of monomers.
IV. Conclusion
The penetrating resin can penetrate into the micropores of the demineralized enamel through the siphoning action of capillaries, which can not only close the demineralization channel and prevent the progression of caries, but also can achieve the masking of enamel leukoplakia by changing the shading rate of the demineralized enamel.
Penetrating resin can significantly improve the microhardness of the enamel surface and increase its stability, thereby providing certain mechanical support for the tooth tissue and preventing the further development of enamel surface collapse and decay. In addition, the penetrating resin can form a smooth and flat surface after polishing, which is not conducive to bacterial adhesion and plaque formation, thereby preventing the recurrence of demineralization.
Of course, the color stability of enamel leukoplakia after resin penetration technology has yet to be improved, and its long-term clinical effect needs to be evaluated.
At this point, this article is over, have you learned about the special repair material of penetrating resin, and if you also have dental problems, remember to go to the hospital and seek help from a doctor in time. If you still have questions about this article, you can leave me a message in the comment area.