The plethora of articles on abfraction have, over many years, been characterized by poor clinical observation followed by erroneously over-complicated reasoning, giving rise to misleading conclusions. Any wide-awake clinician will see the flaws in the observations in seconds. They stand out a mile.
"Examining the Prevalence and Characteristics of Abfractionlike Cervical Lesions in a Population of U.S. Veterans" by Dr. Bradley T. Piotrowski and colleagues in December JADA looked at the role of attrition, erosion and abfraction.
The study found 75 percent to have been a probable abrasion component and only 13 percent (that is, four subjects) to have shown the signs of erosion. Indeed, one-half of that group (two subjects) had severe gastric reflux. Therefore, only two subjects showed "normal" erosion. This is scarcely credible, two out of 36. These subjects must then have been the ones featured in Figures 1 and 4 where erosion is identified easily.
In Figure 1, there clearly is an erosive component supplementing the abrasive component in reducing the occlusal surfaces, as well as sculpting the buccal lesions. The dentition exhibited in Figure 1 is typical for an enthusiastic exponent with the toothbrush and with a diet rich in fruit, fruit juice, vegetables and possibly carbonated soft drinks (the latter possibly less likely in this age-group cohort). It is immediately recognizable to any clinician as an erosion-assisted wear pattern.
Figure 4 shows similar, but less advanced, loss of tooth form with facet development from opposing tooth contacts. The first premolar has cervical dentin showing where it is suffering surface loss. The cusp tip of this tooth has been worn through to dentin, representing a loss of enamel of about 1.5 millimeters. The underlying dentin has eroded even further. To any experienced clinician, this picture is typical of abrasion supplemented by erosion.
The cervical lesion is defined to a sweeping crescent by the enamel margin (probably with little or no significant loss of enamel), and it also is defined precisely to a curve of lesser radius by the cuff of gum. It will be interesting to hear the explanation of why flexure and induced stress should be so respectful of the presence of the gingival margin.
Automobile shock absorbers, valve stems pushrods, conrods, and so forth do not exhibit abfraction. How does "fracturing off" of particles always provide such a fine, sweeping, smooth surface? What model in engineering or biology shows such a process?
In plain language, we are looking at surfaces subjected to acidic degradation, coupled to abrasion and swept by toothbrush bristles. The surfaces in question always are swept surfaces, contrary to assertions of earlier contributors. Those mysterious sculpted surfaces hidden under the gingival cuff were not always under the gingival cuff.
This is only intended as a letter in response to the article quoted, and I do not intend filling several pages with further critiques of this article or others. I could certainly do so, such has been the poor level of observation of so many supposedly "mysterious" features of these noncarious lesions and an uncritical acceptance of the abfraction theory. I suspect that this is more to do with the reluctance of clinicians to cast doubt on theories of "occlusal experts," even when the facts do not fit.
Researchers are obligated to be more observant of the rules of scientific objectivity and more observing when collecting their data. When the presence of a variable shows no discernible difference from the absence of that variable in quantity or quality of the result observed, then that variable is not a significant factor. The tooth that exhibits an abfractionlike lesion, but that has no contact whatsoever with an opposing tooth, is such a "control."
Objective conclusions should be drawn, or do we suspend objectivity rather than sink an elegant theory?
On such a scant foundation of evidence of abfraction as found in the article, it is not responsible to advocate interference with sound enamel by occlusal adjustment.
