Tanaka-Johnston Prediction Calculator

Named Tanaka–Johnstonhistorical population regressions:half four-lower-incisor sum+10.5mandibular,+11maxillary per quadrant in mm. Not observed unerupted tooth widths, universal cohort accuracy or orthodontic treatment decision.

Description

Tanaka–Johnston prediction estimates unerupted canine and premolar widths from four lower incisors.

Tanaka–Johnston prediction estimates unerupted canine and premolar widths from four lower incisors.^[1]

Its fixed regression constants describe a particular predictive convention rather than an individual tooth measurement. Use this tool to calculate the stated observation or conditional model from supplied measurements.

When to use Tanaka-Johnston Prediction Calculator

Use this tool to calculate the stated observation or conditional model from supplied measurements. Establish the qualified examination or measurement context, matching instrument/protocol edition, site order and units.

How to use Tanaka-Johnston Prediction Calculator and understand its results

Establish the qualified examination or measurement context, matching instrument/protocol edition, site order and units.
Enter independentlyMeasuredFourLowerIncisorWidthsMm, using the field meanings and rules below, then run the tool.
Read result.conditionalMandibularCaninePremolarWidthPerQuadrantMm, result.conditionalMaxillaryCaninePremolarWidthPerQuadrantMm. Interpret each field using the units, signs and evidence rules below.
If input validation fails, correct the reported field and run again. Before applying a successful result, check the stated reference scope, units, assumptions and any retained unknown evidence.

Input field	Meaning	Value type	Requirement
independentlyMeasuredFourLowerIncisorWidthsMm	Independently measured four lower incisor widths mm	list of number	Required

Supply exactly four positive lower-incisor widths in millimeters in an independently qualified measurement set. Sum them and return sum/2+10.5 for a mandibular quadrant and sum/2+11 for a maxillary quadrant. These are per-quadrant predictions; no individual calibration, uncertainty or population correction is fitted.

predictedMandibularWidthPerQuadrantMm=ΣfourWidths/2+10.5; predictedMaxillaryWidthPerQuadrantMm=ΣfourWidths/2+11

Apply the field units and exact ordering, boundary and evidence rules above.

Output field	Meaning	Value type
result	Structured result containing the calculation or selected reference fields below	object
result.conditionalMandibularCaninePremolarWidthPerQuadrantMm	Conditional Mandibular Canine Premolar Width Per Quadrant Mm; use the units, sign convention and calculation stated above	number
result.conditionalMaxillaryCaninePremolarWidthPerQuadrantMm	Conditional Maxillary Canine Premolar Width Per Quadrant Mm; use the units, sign convention and calculation stated above	number

json

{
  "input": {
    "independentlyMeasuredFourLowerIncisorWidthsMm": [
      5,
      5,
      5,
      5
    ]
  },
  "output": {
    "result": {
      "conditionalMandibularCaninePremolarWidthPerQuadrantMm": 20.5,
      "conditionalMaxillaryCaninePremolarWidthPerQuadrantMm": 21
    }
  }
}

Limitations and assumptions

Its fixed regression constants describe a particular predictive convention rather than an individual tooth measurement. Results depend on the independently established measurement basis and the exact model assumptions above.

Every listed input requires an explicit value. Unexpected fields, incorrect value types, nonfinite numbers and sparse numeric arrays fail validation; tool-specific bounds and alignment rules apply as described above. Extremely large inputs or outputs can also be rejected. An input error is distinct from a successful calculation that reports a false comparison or retains unknown evidence.

Alternative or Complementary methods

Use Tooth Eruption Age Lookup to examine a related aspect: Tooth eruption timing varies with tooth, dentition, population and assessment definition.

Use Tooth Formation Stage Lookup where its separate inputs and scope apply: Tooth formation stages describe developmental features under a named staging system.

References

Tanaka-Johnston Prediction Calculator — tool.io

Similar or alternative tools

Tooth Eruption Age Lookup
Tooth eruption timing varies with tooth, dentition, population and assessment definition.
Tooth Formation Stage Lookup
Tooth formation stages describe developmental features under a named staging system.