Understanding a Skeletal Class II Through Cephalometric Analysis

Cephalometric analysis is not about collecting numbers—it is about understanding the craniofacial relationships behind those numbers.

In this case study, we will examine a patient presenting with a skeletal Class II pattern and explore how the different measurements contribute to the overall diagnosis.

Step 1: Identifying the Sagittal Skeletal Relationship

The first measurements most orthodontists look at are the sagittal indicators.

• ANB: 5.83°
• Wits Appraisal: +4.92 mm

Both measurements indicate a Skeletal Class II relationship.

An ANB greater than 4° generally suggests a Class II skeletal discrepancy, while a positive Wits appraisal confirms that the maxillary and mandibular bases are not ideally related in the sagittal dimension.

In this case, both indicators point in the same direction, increasing confidence in the diagnosis.

Step 2: Determining the Origin of the Class II

Once the Class II relationship is identified, the next question becomes:

Is the discrepancy caused by the maxilla, the mandible, or both?

• SNA: 84.43°
• SNB: 78.60°

The SNB value is close to normal, suggesting that the mandible is reasonably well positioned.

The SNA, however, is increased, indicating a forward position of the maxilla.

The skeletal Class II therefore appears to be primarily related to maxillary protrusion rather than mandibular retrusion.

Step 3: Evaluating the Vertical Pattern

Vertical growth pattern is a critical component of orthodontic diagnosis.

• MMPA: 24.98°
• FMPA: 22.42°
• Ar-Go-Me: 125.86°
• %LAFH: 55.35%

Most vertical indicators fall within normal limits.

The patient can therefore be classified as normodivergent.

This is generally favorable from a treatment perspective because there is no evidence of excessive vertical growth or hyperdivergence.

An Interesting Finding: The Palatal Plane

One measurement deserves special attention:

• SN-Mx: 2.37°

This value is significantly below the normal range.

It suggests a tendency toward a flatter palatal plane orientation and contributes to a mild hypodivergent tendency despite the overall normodivergent pattern.

This illustrates why experienced orthodontists rarely rely on a single measurement. Instead, they evaluate the entire cephalometric pattern.

Step 4: Analyzing Incisor Position

• Upper Incisor to Maxillary Plane: 103.18°
• Lower Incisor to Mandibular Plane: 93.55°
• Interincisal Angle: 138.29°

Both upper and lower incisors are positioned close to their respective norms.

Unlike many Class II patients, this case does not exhibit significant dental compensation.

The interincisal angle also remains within normal limits, confirming a relatively balanced incisor relationship.

A Closer Look at the Lower Incisors

• A-Pog to Lower Incisor: -3.51 mm

This measurement indicates a slight retroclination or retrusion of the lower incisors.

Although the overall lower incisor inclination remains within normal limits, this value suggests a mild compensatory adaptation to the skeletal Class II pattern.

Step 5: Soft Tissue Evaluation

A complete diagnosis must include soft tissue analysis.

• Nasolabial Angle: 128.53°
• Upper Lip to E-Plane: 1.39 mm
• Lower Lip to E-Plane: -0.19 mm

The nasolabial angle is considerably increased, suggesting a relatively retrusive soft tissue profile.

Both lips are positioned behind the expected E-plane values, supporting the impression of a less protrusive facial profile.

This finding becomes particularly important when considering extraction decisions, as excessive incisor retraction could further flatten the profile.

Clinical Summary

The cephalometric analysis reveals:

• Skeletal Class II relationship
• Primary maxillary protrusion
• Normal mandibular position
• Normodivergent vertical pattern
• Mild hypodivergent tendency
• Minimal dental compensation
• Relatively retrusive soft tissue profile

What Can We Learn From This Case?

This case demonstrates why cephalometric analysis should be viewed as a diagnostic framework rather than a collection of isolated numbers.

Although the ANB and Wits values immediately identify a skeletal Class II relationship, the complete analysis reveals a much more nuanced picture: a maxillary-driven discrepancy, a favorable vertical pattern, limited incisor compensation, and soft tissues that require careful consideration.

Ultimately, successful orthodontic diagnosis comes not from measuring values, but from understanding how those values interact to describe the patient as a whole.