Orthodontic Principles – Malocclusion, Braces, Clear Aligners

Overview

Orthodontics is a specialized branch of dentistry focused on diagnosing, preventing, and correcting malocclusion — the misalignment of teeth and jaws that affects function, aesthetics, and oral health. Orthodontic treatment aims to improve the coordination between teeth, dental arches, and jaw structures through controlled application of forces over time. 

Malocclusion

Malocclusion refers to an imperfect relationship between the upper and lower teeth when the jaws are closed. It may involve irregular spacing, crowding, overbite, underbite, and crossbite, and can affect chewing, speech, and facial symmetry. 

Classification of Malocclusion

The most widely used classification system is based on Angle’s classification, which categorizes malocclusion by the molar relationship:

• Class I: Normal molar relationship with misaligned teeth
• Class II: Upper teeth significantly forward of lower teeth
• Class III: Lower teeth forward of upper teeth 

Assessment for treatment considers both functional and aesthetic impact, and not all malocclusions require correction if they do not impair oral function or patient satisfaction. 

Orthodontic Appliances

Orthodontic treatment uses various appliances to apply controlled forces that gradually move teeth and adapt jaw relationships.

Braces

Braces are the traditional fixed appliances used in most orthodontic treatments. They consist of:

• Brackets bonded to the teeth
• Archwires that connect the brackets and apply force
• Ligatures or clips that secure wires
  Fixed braces provide precise control of tooth movement and can address complex cases of malocclusion. 

Variants of fixed braces include self-ligating systems (which use clips instead of elastic ligatures) that may reduce friction and improve oral hygiene. 

Clear Aligners

Clear aligners are removable, transparent trays custom-made to gradually shift teeth into desired positions. They have become increasingly popular due to their discreet appearance and ease of hygiene maintenance. 

Clear aligners are most effective for mild to moderate malocclusions such as crowding and spacing, and treatment typically involves a series of aligners worn for about 20–22 hours per day, with each set worn for one to two weeks before progressing to the next. 

Modern clear aligner therapy uses digital scanning and computer-guided treatment planning to design sequential stages of movement. 

Mechanism of Tooth Movement

Orthodontic appliances exert gentle, continuous forces on teeth. These forces stimulate bone remodeling — resorption on the pressure side and deposition on the tension side — allowing teeth to shift within the jawbone over time. Appropriate force magnitude and direction are critical for safe and effective tooth movement.

Treatment Process

1. Diagnosis & Planning – Clinical exam, dental impressions or digital scans, and radiographs
2. Appliance Placement – Braces bonded or aligners fitted
3. Active Movement Phase – Regular adjustments (braces) or aligner changes
4. Retention – Use of retainers after treatment to maintain results

Clinical Relevance

• Improved Functionality: Correcting occlusion enhances chewing, speech, and jaw comfort.
• Oral Health: Aligned teeth are easier to clean, reducing risk of decay and periodontal issues.
• Aesthetic Outcomes: Straightened teeth contribute to facial harmony and patient confidence.

Both conventional braces and clear aligners play essential roles in modern orthodontic practice; choice of appliance depends on case complexity, patient needs, and treatment goals.