Bolton's ratio variations in Angle's Class I, Class II and Class III malocclusions: An observational study

Area of Science:

• Dentistry
• Orthodontics
• Dental Morphology

Background:

• Understanding tooth size discrepancies is crucial in orthodontics.
• Bolton's ratios (Overall and Anterior) are key metrics for assessing inter-arch tooth material balance.
• Malocclusions can present with varying tooth size relationships.

Purpose of the Study:

• To compare Bolton's Overall Ratio and Anterior Ratio in different Angle's malocclusion classes.
• To identify potential tooth material discrepancies in various malocclusion types.

Main Methods:

• 105 orthodontic patient study casts were analyzed.
• Patients were classified into Angle's Class I, II, and III (n=35 each).
• Mesio-distal tooth widths were measured, and Bolton's ratios were calculated.

Main Results:

• The overall sample showed mean ratios close to Bolton's ideal.
• Class I and III malocclusions exhibited increased mandibular anterior tooth material.
• Class II malocclusions showed excess maxillary anterior tooth material.

Conclusions:

• Significant variations in tooth material distribution exist across malocclusion types.
• Mandibular anterior excess is noted in Class I and III malocclusions.
• Maxillary anterior excess is observed in Class II malocclusions, impacting inter-arch harmony.