Standard Combined Analysis

The Standard Combined analysis is not the work of a single author. It is the composite template that emerged in practice from the classical analyses — Steiner, Ricketts, McNamara, Tweed and Jacobson's Wits appraisal — gathering the measurements from each that proved most diagnostically useful, and dropping the ones that duplicate each other or that rarely change a treatment decision. Variants of this template are the default report in maxillofacial radiology centres and in most cephalometric software.

Its purpose is coverage with economy. Each classical analysis is strong in one area and thin in others: Steiner is built around the cranial base and is excellent for the sagittal (front-to-back) jaw relationship but weak on vertical proportion; McNamara replaces angles with millimeters and is better for surgical planning; Ricketts contributes growth-direction measurements; Tweed contributes the lower incisor's relationship to its own jaw; the Wits appraisal cross-checks the sagittal relationship without depending on the cranial base at all. Combining them into sixteen measurements across four groups gives a complete diagnostic picture from a single tracing, with built-in cross-checks where two authors describe the same relationship in different ways.

What It Evaluates

The analysis is organized into four blocks, read in order:

Sagittal skeletal — where each jaw sits front-to-back and how the two relate to each other, measured both against the cranial base (Steiner) and independently of it (Wits, McNamara's Nasion perpendicular).
Vertical skeletal — the divergence of the face and the direction of mandibular growth: is this a deep-bite or an open-bite pattern, and is the palate itself tilted?
Dentoalveolar — where the upper and lower incisors sit and how they are angled, both relative to their own bone and relative to each other.
Soft tissue — the lip profile against the aesthetic plane, which is what determines whether a skeletally correct plan will also look right.

The value of reading them in that order is that each block constrains the next: the skeletal pattern determines how much dental compensation is acceptable, and the soft-tissue profile determines whether that compensation is aesthetically viable.

Learn more: Orthodontics, Cephalometric Analysis — StatPearls, NCBI Bookshelf

Key Measurements

Sagittal skeletal

SNA — the angle between the Sella-Nasion cranial base line and point A, describing how far forward the maxilla sits relative to the skull base. Normal value: 82° ± 2°.
SNB — the same reference applied to point B, describing the anteroposterior position of the mandible. Normal value: 80° ± 2°.
ANB — the difference between SNA and SNB, summarizing the relationship between the two jaws. Normal value: 2° ± 2°. Above 4° suggests a skeletal Class II tendency, below 0° a skeletal Class III tendency.
Wits appraisal (AO-BO) — the same sagittal relationship measured along the patient's own occlusal plane instead of the cranial base, used as a cross-check on ANB. Normal value: approximately +1 mm (males), 0 mm (females).
A point to Nasion perpendicular — the maxilla's position against a vertical line dropped from Nasion perpendicular to the Frankfort Horizontal, expressed in millimeters. Normal range: 0 to +1 mm.
Pogonion to Nasion perpendicular — the chin's position against that same vertical reference. Normal range: approximately -4 to 0 mm (males), -4 to -2 mm (females).

Vertical skeletal

Mandibular plane to SN — the angle between the cranial base line and the mandibular plane, describing vertical facial divergence. Normal value: 32° ± 4°. Above roughly 35° indicates a hyperdivergent (vertical, open-bite-prone) pattern; below roughly 28° a hypodivergent (horizontal, deep-bite-prone) one.
FMA (Frankfort-Mandibular Plane Angle) — the same divergence measured against the Frankfort Horizontal instead of the cranial base. Normal value: 25° (clinical range approximately 20°-30°).
Facial Axis — the angle between the Basion-Nasion line and the Pterygoid-Gnathion line, describing the direction of mandibular growth rather than its current divergence. Normal value: 90° ± 3.5°. Above 90° indicates a forward growth rotation; below 90° a backward one.
Palatal plane angle — the inclination of the palatal plane (ANS-PNS) relative to the cranial base, which detects a tipped maxilla. Normal value: approximately 8° ± 3° to SN (close to 0°-1° when measured against the Frankfort Horizontal).

Dentoalveolar

U1-NA, angle and distance — the inclination and forward protrusion of the upper incisor relative to the Nasion-A line. Normal values: 22° ± 2° and 4 mm ± 2 mm.
L1-NB, angle and distance — the inclination and forward protrusion of the lower incisor relative to the Nasion-B line. Normal values: 25° ± 2° and 4 mm ± 2 mm.
IMPA (Incisor-Mandibular Plane Angle) — the angle between the long axis of the lower incisor and the mandibular plane, describing how upright the lower incisor stands over its own jawbone. Normal value: 90° (clinical range approximately 85°-95°).
Interincisal angle (U1-L1) — the angle between the long axes of the upper and lower incisors, reflecting overall incisor proclination. Normal value: 131° ± 6°.

Soft tissue

Upper lip to E-plane — the distance from the upper lip to Ricketts' aesthetic plane, the line from the tip of the nose to the soft-tissue chin. Normal value: approximately -4 mm ± 2 mm (the lip sits behind the line).
Lower lip to E-plane — the same measurement for the lower lip. Normal value: approximately -2 mm ± 2 mm.

Learn more: Cephalometric Analysis — Wikipedia

Clinical Interpretation

The sagittal block is read first, and the two independent routes to the same answer are what make it robust. SNA and SNB locate each jaw individually; ANB summarizes their relationship. But ANB can be distorted when Nasion sits unusually high or low, which is exactly the situation the Wits appraisal and the Nasion perpendicular measurements exist to catch: when ANB and Wits agree, the sagittal diagnosis is secure; when they disagree, the cranial base is atypical and the millimeter-based measurements should be trusted over the cranial-base angle. A high ANB with normal SNA and low SNB points to a retrusive mandible rather than a protrusive maxilla — a distinction that decides whether treatment targets the upper or the lower jaw.

The vertical block then sets the limits of what is achievable. A hyperdivergent pattern — high mandibular plane angle, facial axis below 90° — resists bite closure, tends to relapse, and makes molar intrusion rather than incisor extrusion the safer mechanic. A hypodivergent pattern behaves the opposite way. The facial axis is worth reading alongside the plane angles because it describes growth direction and changes little with age, so in a growing patient it forecasts where the mandible is heading rather than just where it is. A tipped palatal plane adds a further caution: part of the apparent vertical discrepancy may be maxillary rotation rather than mandibular divergence.

The dentoalveolar block is interpreted against the skeletal findings, never on its own. Incisor angles outside the norm are often compensation rather than pathology — a proclined upper incisor in a Class III skeleton is the dentition disguising the jaw discrepancy, and "correcting" it to the textbook value would unmask the skeletal problem rather than fix it. IMPA is the key figure for stability, since a lower incisor tipped forward off its basal bone is the classic setup for crowding relapse. Finally, the soft-tissue block arbitrates: two plans that produce identical skeletal numbers can produce very different profiles, and lips well behind the E-plane in a patient with a prominent nose argue against further retraction regardless of what the hard-tissue measurements permit.

Learn more: Cephalometric Analysis — Norms and Measurement Reference, BCeph