Posterior_Direct_Restorations Salvatore_compressed
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FIG 3-44 (a) Noncavitated white/brown spot on the mesial surface of the mandibular right first molar. The surface is directly explorable because the adjacent second premolar has not fully erupted. (b) Field isolation. Dam is used to protect the second premolar from etching (carried out using 15% hydrochloric acid for 2 minutes). The acid gel is mixed to promote etching of the surface enamel. (c) The surface is wetted with ethanol and then dried to remove moisture. (d) The surface is rendered porous and dehydrated. Note that the brown discoloration has disappeared following the prolonged etching stage. (e) Prolonged and repeated application (3 minutes first application, 1 minute second application) of low- molecular-weight resin (triethylene glycol dimethacrylate [TEGDMA]). After each of the first two applications, the resin is blown dry and cured for 40 seconds. (f) Final curing is performed under glycerin gel to allow the resin layer to set properly, uninhibited by the presence of oxygen. (g) End result. Note that the WS looks smaller. This is because the refraction index of the infiltrating resin is very similar to that of the healthy enamel. More peripheral, shallower areas of the WS have therefore been masked by the cured resin.
Proper diagnosis of lesions in these areas is essential for application of the infiltration procedure. The diagnostic investigations listed earlier in this chapter62 must therefore be combined to rule out the presence of any cavitation. Cavitation of a “closed” interproximal surface (where two teeth are in contact) inevitably represents an ecologic niche favorable to the establishment and persistence of cariogenic bacteria. In such cases, conventional restoration actions are imperative, as explained in the
following chapters. Discrimination between cavitated and noncavitated lesions is therefore essential, given the inherently irreversible nature of the restoration procedures63 and the scientific unreliability of cavitated lesion infiltration procedures.
As explained earlier in this chapter, the presence of cavitation on an interproximal surface cannot be taken for granted except for lesions with radiographic involvement of the central or internal third of the dentin (D2 or D3 in the E-D classification).26,64 In radiographic classes E1, E2, and D1, the absence of cavitation must always be confirmed by direct observation of the surface (preferably under magnification) after separating (Fig 3-45), cleaning, and drying. After confirming the absence of cavitation, the dentist will be able to assess what to do based on various considerations. Table 3-3 provides some suggestions for action based on the patient’s clinical and behavioral characteristics.
FIG 3-45 Gentle separation of the interproximal space reveals the presence of a cavitated lesion on the distal surface of the first premolar.
TABLE 3-3 Suggestions for action based on patient clinical and
behavioral characteristics
General risk of caries |
The lower the patient’s overall risk of caries, the more useful it |
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will be to consider the natural process of remineralizing |
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noncavitated lesions. For higher risk classes, remineralization |
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could be combined with infiltration of noncavitated interproximal |
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lesions. In more severe cases, particularly when patients lack the |
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necessary compliance, conventional restorations could be |
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considered even for lesions in radiographic classes E2 and D1. |
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Local risk of caries |
If the interproximal demineralization site is more distal and/or |
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difficult to clean, it will be more useful to combine resin infiltration |
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with remineralization. |
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Lesion activity |
Remineralization alone will be more useful in cases where the |
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lesion is inactive, displays long-term stability on radiographs, and |
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is in a well-cleaned area and the patient is very compliant. Active |
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noncavitated lesions should always be treated by at least |
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remineralization and/or resin infiltration; restoration may be |
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necessary in selected cases. |
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Home compliance |
The higher the patient’s home compliance, the more likely the |
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procedure is to be remineralization alone. Resin infiltration or |
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restoration may be required for less compliant patients. |
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Compliance with regular |
If the patient complies well with regular checkups, |
checkups |
remineralization and/or infiltration procedures are more likely to |
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be the methods of choice. |
|
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The principle of resin infiltration is based on the penetration of a fluid resin into the body of the initial caries lesion by capillary action. Given the high mineral content of the enamel surface, it must be made porous to allow the resin to pass through it.65,66 Over the years, various resin infiltration techniques have been suggested. These differ with regard to the method of preparing the interproximal enamel surface, which may be made porous using abrasive metal strips and 37% orthophosphoric acid67 or 15% hydraulic acid,65 for example, and with regard to the infiltrating resin, which sometimes consists of an enamel-dentinal bonding agent for routine outpatient use57,67 and sometimes is composed of low-molecular- weight resins specifically dedicated to the infiltration process.65 At the time of this writing, the dental industry only offers one dedicated kit for this purpose; therefore the procedure for using this kit is described here.
The system is based on etching with 15% hydrochloric acid and infiltration with a low-molecular-weight resin (TEGDMA).
The treatment sequence involves the following (Fig 3-46):
