Functional occlusion after fixed appliance orthodontic treatment: a UK three-centre study

Area of Science:

• Dentistry
• Orthodontics
• Occlusion

Background:

• Fixed appliance therapy is a common orthodontic treatment.
• Assessing functional occlusal contacts is crucial for treatment success.
• Previous studies have reported varying prevalence of occlusal discrepancies.

Purpose of the Study:

• To determine the prevalence of functional occlusal contacts in patients treated to a Class I incisor relationship.
• To evaluate the impact of overbite on occlusal contacts.
• To compare findings with existing literature.

Main Methods:

• One hundred eighty-eight subjects from three UK orthodontic centers were assessed.
• Helkimo's dysfunction indices were used to evaluate mandibular mobility, clinical dysfunction, and occlusal status.
• Examiner assessed occlusal contacts, including RCP (CR)-ICP (CO) discrepancies, non-working side contacts, and posterior contacts on protrusion.

Main Results:

• RCP (CR)-ICP (CO) discrepancies were found in 18% of cases.
• Non-working side contacts were present in 31% of subjects.
• Posterior contacts on protrusion occurred in 23% of subjects.
• Interferences were more frequent in cases treated by postgraduate students (P < 0.05).
• An overbite > 2.4 mm significantly reduced non-working side and posterior protrusive contacts (P < 0.001).

Conclusions:

• The prevalence of functional occlusal discrepancies in this UK sample is comparable to American literature.
• Orthodontic treatment aiming for a Class I incisor relationship can result in occlusal interferences.
• A deeper overbite may be a protective factor against certain occlusal interferences.