How to read and calculate refinement rates correctly

Few metrics are passed around the aligner industry as casually as the claim that one's own refinement rate sits "at around 20 percent". It appears in manufacturer presentations, course materials and practice conversations, usually without any indication of how it was measured. The available data paints a different picture. Anyone who wants to calculate the economics of aligner therapy should understand why the figure, in this form, is rarely reliable.

What the data actually shows

The most revealing recent source is a survey published in 2025 in the Dental Press Journal of Orthodontics (Ladewig VM et al., 2025;30(2):e2524248). In a voluntary questionnaire, 188 Brazilian orthodontists reported a total of 2,937 completed aligner treatments from the previous 24 months. The result: at least one refinement was required in 70.31 % of cases, and 21.95 % of cases needed at least two. What stands out is the experienced cohort: among orthodontists with more than 20 years since specialisation, the figure rose to 82.3 %. That does not speak against their skill; it points to two plausible explanations: experienced clinicians tend to take on the more difficult cases, and they report more openly, because to them a refinement is not a blemish but a normal step in treatment. One methodological caveat: the figures are based on self-reported cases from a voluntary survey, not on a documented case series.

These values are consistent with the rest of the literature, which cites average refinement rates of 40 to 60 %, with an industry average of around 2.5 refinement scans per case (industry estimate cited in the manufacturing partner's publications, as of 01/2026). Between these findings and the frequently quoted 20 percent mark lies a gap that cannot be explained by treatment quality alone, but rather by how the measurement is taken.

Measurement error no. 1: a blended figure with no reference to complexity

A single percentage across all case severities is close to meaningless. Mild anterior crowding naturally refines at a fraction of the rate of a severe multiplanar correction. Two labs or two practices can therefore both report "20 percent" while having completely different case portfolios and completely different cost structures. In the assessment of our manufacturing partner, a benchmark without complexity matching is confidence borrowed from someone else's marketing rather than a reliable metric: the number feels good, but it cannot support a decision.

Measurement error no. 2: counting active cases as completed

The second, more subtle error: open treatments are included in the rate as if they were finished. A case that has not yet reached its planned endpoint simply has not had the opportunity to need a refinement. As long as the caseload is growing, the rate looks systematically flattering, until the cases "mature" and the correction trays materialise after all. Anyone who wants to evaluate a refinement rate seriously may only count confirmed completed cases whose expected treatment duration has fully elapsed.

Why the number matters economically

Clinically, a refinement is not a failure; it is often a regular part of finishing. From a business perspective, however, it is a cost item: additional planning, additional manufacturing, additional shipping and support on a case that has already been calculated and paid for once. A worked example from the manufacturing partner's publications makes the order of magnitude tangible: at 50 cases per month and an actual refinement rate of 20 %, ten additional production rounds arise every month. These costs never appear on any individual invoice because they are spread across months. If the real rate is closer to the 70 % found in the survey, the calculation shifts accordingly and substantially. In short: if you do not know your true, complexity-segmented closed-case rate, you do not know your case costs.

Measuring correctly in three steps

1. Count only completed cases. The rate should include only treatments whose planned duration has fully elapsed and whose completion has been documented.
2. Segment by complexity. Separate at least three classes (mild, moderate, complex); only then do comparisons between time periods, clinicians or systems become meaningful.
3. Read the rate as a process output. The refinement rate is the result of case selection, planning quality, staging and the force retention of the material. All of these levers can be deliberately improved.

Putting it into practice

An honestly measured refinement rate of 50 or 60 % is no cause for alarm; it simply reflects the reported reality of aligner therapy. The problem is not the number, but the illusion of a lower one. For collaboration with labs and manufacturing partners, one simple screening question follows: how is the quoted rate measured, across completed cases and segmented by complexity? If you do not get a precise answer, do not carry the number into your own calculation.

The clinical assessment of each individual case, that is whether a refinement is indicated, how many correction steps are appropriate and when a treatment is considered complete, always remains the responsibility of the treating dentist. Data does not replace diagnostics; it makes your own calculation more honest.