In a word…Yes! Dentists use the term “arrested” to describe dental caries in which the decay process has stopped and the decay is no longer active. In lay terms, arrested can be considered the same as healed.
The arrest and healing of tooth decay has been described many times in leading dental text books and journals.
A few examples (to paraphrase):
Teeth containing large cavities, which ordinarily would have an area of softened dentin surrounding the zone of destruction, were found instead to be very dense. Open cavities showed no signs of progress months after they were first observed.
Dr J.D. Boyd, MD and Dr. C.L. Drain, DDS, 1928
In active decay the tissue for some distance below the surface is more or less depleted in minerals and feels “soft” to the dental probe. In early stages of arrest the surface zone may feel rough or leathery. In the next stage the surface is found to be hard but rough, and later the irregularities may be removed by mechanical abrasion. This process may take months or years, but eventually the surface may become quite hard, smooth and polished, but active decay may have stopped long before this stage is reached.
Dr May Mellanby, DSc, 1933
One of the most severe tests of a nutritional program, accordingly, is the test of its power to check tooth decay completely, even without fillings. If diet has been sufficiently improved, bacterial growth will not only be inhibited, but the leathery decayed dentin will become mineralized from the saliva by a process similar to petrification. When scraped with a steel instrument it frequently takes on a density like very hard wood and occasionally takes even a glassy surface.
Dr W.A. Price, DDS, 1934
From "Essentials of Dental Caries", Dr Edwina Kidd, 3rd Ed, 2005.
To the left is an example of an arrested cavity. Despite the decay having advanced well into dentin, the exposed dentin was hard and shiny. The tooth had been in this state for at least 10 years.
This example is admittedly not very attractive (to say the least), but does show that tooth decay can heal even when it has advanced beyond the enamel and well into the dentin.
Note that while the decay has been arrested, the cavity does not infill.
From "Oral Histology: Development, structure and function", Dr A.R. Ten Cate, 2nd Ed., 1985. (click for larger image)
When a tooth is attacked by decay or suffers an injury such as a chip, if nutrition is good, it responds by depositing what is referred to today as reparative or tertiary dentin. (In Dr Mellanby’s time it was called secondary dentin). The reparative dentin forms only in the area affected by decay or injury, and is an attempt by the tooth to protect the pulp.
As healing progresses, the decayed and exposed dentin can become remineralized, ultimately forming a hard, dense, glassy surface.
In her careful experiments, Dr May Mellanby demonstrated that the same nutritional conditions that support development of strong, well mineralized teeth, also support the arrest of dental decay, development of reparative dentin and tooth remineralization. That is, optimal supplementation of vitamin D, together with adequate calcium and phosphorus and a calcifying diet with restricted intake of sugar and cereal grains. Dr Weston Price found even better results when vitamin K2 was also supplemented.
From Dr May Mellanby
This is an example of a healed tooth viewed under the microscope after treatment with the calcifying diet rich in vitamin D, calcium and phosphorus. The decay has been fully arrested. There is a thick layer of well-calcified reparative dentin (2D) protecting the pulp, and the surface is hard and smooth with no decay.
When tooth decay is active, the goal of nutritional supplements and diet is to create the optimal dietary and nutritional environment that harnesses the body’s defenses and supports the natural arrest of the decay and remineralization of the affected areas. In other words, to create the conditions that allow teeth to heal…naturally and without dental intervention.