System comprising: - an acquisition apparatus for the acquisition of a first image (Ia 1) and optionally of a second image (Ia 2) of a dental arch of a patient, said first image being called the first current image and said second image being called second current image, a region of said arch appearing in said image(s), said first image being acquired under first real acquisition conditions and said second image being acquired under second real acquisition conditions, and - a computer program product comprising program-code instructions for implementing, when the program is executed by computer, a method comprising the following steps: B) exploration of a three-dimensional digital model representing said dental arch of the patient, which is called the reference model to be enriched, in such a manner as to determine a first view of the reference model to be enriched, in a first direction of observation, or first reference image, said first reference image exhibiting a maximum match with the first current image; C) determination, by comparison of the first reference image and of the first current image (Ia 1), of a first orphan point (32 1) represented on the first current image (Ia 1) and not represented on the first reference image (Ir 1) when the first current image is in a first register position in which it is superposed, in the space of the reference model to be enriched, with the first reference image (Ir 1); D) addition, in the reference model to be enriched, of a point, called the parent point, on a first straight line (Δ 1) parallel to the first direction of observation and passing through the first orphan point (32 1) in the first register position. - an acquisition apparatus for the acquisition of a first image (Ia 1) and optionally of a second image (Ia 2) of a dental arch of a patient, said first image being called the first current image and said second image being called second current image, a region of said arch appearing in said image(s), said first image being acquired under first real acquisition conditions and said second image being acquired under second real acquisition conditions, and - a computer program product comprising program-code instructions for implementing, when the program is executed by computer, a method comprising the following steps: B) exploration of a three-dimensional digital model representing said dental arch of the patient, which is called the reference model to be enriched, in such a manner as to determine a first view of the reference model to be enriched, in a first direction of observation, or first reference image, said first reference image exhibiting a maximum match with the first current image; C) determination, by comparison of the first reference image and of the first current image (Ia 1), of a first orphan point (32 1) represented on the first current image (Ia 1) and not represented on the first reference image (Ir 1) when the first current image is in a first register position in which it is superposed, in the space of the reference model to be enriched, with the first reference image (Ir 1); D) addition, in the reference model to be enriched, of a point, called the parent point, on a first straight line (Δ 1) parallel to the first direction of observation and passing through the first orphan point (32 1) in the first register position. B) exploration of a three-dimensional digital model representing said dental arch of the patient, which is called the reference model to be enriched, in such a manner as to determine a first view of the reference model to be enriched, in a first direction of observation, or first reference image, said first reference image exhibiting a maximum match with the first current image; C) determination, by comparison of the first reference image and of the first current image (Ia 1), of a first orphan point (32 1) represented on the first current image (Ia 1) and not represented on the first reference image (Ir 1) when the first current image is in a first register position in which it is superposed, in the space of the reference model to be enriched, with the first reference image (Ir 1); D) addition, in the reference model to be enriched, of a point, called the parent point, on a first straight line (Δ 1) parallel to the first direction of observation and passing through the first orphan point (32 1) in the first register position.