Really these terms Aesthetic and Cosmetic Dentistry should be synonymous, but often they are not really the same. In my opinion for dentistry to be truly aesthetic it must appear natural and in harmony with a patients other teeth and face. All too often patient's smiles are made over in a cosmetic but not natural way. The restored smiles call attention to the restorations and say look at me! Look how bright my teeth are, look how uniform my teeth are. This is what some patients' want- uniform and bright white smile. It may not look completely natural, but that isn't the point.
Just as when a woman has bright highlights placed in her hair it calls attention to her beautiful hair, cosmetic dentistry can call attention to a patient's beautiful smile and highlight the smile. This is a great idea, but if the restored smile is perceived as naturally belonging to the patient then it is even more attractive. Tooth shapes must be natural both in shape and color. There must be a blending of a patient's natural teeth with restored teeth. If a patient is not restoring their bicuspids then often bleaching must be part of the treatment plan for a truly aesthetically restored smile. Also even though straight and perfectly aligned teeth are in general desired aesthetically restored smiles shouldn't have a perfect alignment, but instead must have edges and tooth alignments with some pleasing variation. Too much symmetry can look static and fake, so truly aesthetic smiles must have some variation in shapes and alignments. The teeth themselves should not be completely monochromatic and should have some translucency close to the edges.
Some ceramicists are loath to introduce variations in alignment and edge positions because they are afraid the case will be found to be unsatisfactory by the patient or the dentist and this is why much cosmetic dentistry has almost a 'cookie cutter" appearance. All the teeth are the same somewhat opaque bright white color and all the alignments are straight, without variation. These smiles are not examples of 'aesthetic' dentistry.
To achieve a truly aesthetic result, often a cosmetic dentist must not be afraid to try out a look - a mock up or dress rehearsal so to speak and make sure the patient likes it. This dress rehearsal should incorporate some pleasing variations in edge position and teeth alignments and once approved by the patient the technician creating the porcelain laminates or crowns must be willing to copy the mock up models when creating a new smile for the patient. Sometimes this can be time consuming, but good work take time and the aesthetic smile that results is usually worth it!