Modules
Module 3: Caries ManagementCaries Risk Classification Table

3.4 Surgical Model Misconceptions

Poor anatomical form, in the absence of caries, does not automatically warrant replacement of the restoration.

Materials failure means replacement.
Traditionally, materials failure (e.g., pitted amalgams, ragged margins, poor contours) meant replacement. Dentists believed that restorations demonstrating certain defects were at risk for recurrent caries. Surgical intervention to replace these defective materials was regarded as warranted for all patients.

Current Evidence: Studies indicate that 50 to 65 percent of restorations are replacements of prior restorations, for various reasons including but not limited to marginal degradation, isthmus fracture, tooth fracture, surface porosity, poor anatomical form, and cervical overhang.31–36 These defects do not represent equivalent risk factors in all patients, nor do they all necessitate total restoration replacement.

Marginal gaps are not a predictor of recurrent dental caries or risk for disease.5 Margins that examining dentists define as “perfect” actually have a gap that is 50 μm or less in width. A margin of 83 μm or less is rated “acceptable.” An MS bacterium is 1 μm wide. Even a clinically “perfect” margin allows easy access for odontopathic bacteria.37 Before beginning a replacement, the dentist should reflect on whether the restoration is being done because of personal habits or a practice philosophy, or whether there is there a scientific rationale for it.20

When considering replacement of an existing restoration because there is a possibility that dental caries recurred, the dentist should weigh the patient’s caries risk category as well as the condition of the restoration. Generally, the decision to restore should be more aggressive for patients in the high- and very-high-risk categories than for patients in the low- and moderate-risk categories. (See the Caries Risk Classification Table. In the absence of active disease, few if any restorations in patients at low risk will need replacement.

Each time a restoration is replaced, its successor is larger25,38 and involves more surfaces. Restorations also weaken teeth. Therefore, the decision to replace an existing restoration must be carefully considered. Dentists should never assume that the new restoration will be an improvement over the one present.