CATEGORY 60 AUSTRALASIAN DENTIST CLINICAL Orthodontic treatment aims to bring teeth into proper alignment, thus improving both the function and aesthetics. There are variety of dental conditions may require orthodontic intervention, including spacing, crowding, tipping, tooth transposition, increased overjet, and deep overbite. Now getting into the treatment of crowding which occurs when there is insufficient space in the dental arch for all teeth to align properly. This results in overlapping or rotated teeth. To correct the crowding and align the teeth, we need to create space, which can be done in two ways: X Extraction therapy – removing selected teeth to create adequate space for alignment. X Non-extraction therapy – expanding the dental arch or moving teeth to gain space without removing any teeth. There has been constant debate among Orthodontists for the extraction vs nonextraction approach over time. The trend started to decline through the 1980s and early 1990s, which had been the era of nonextraction therapy. Interestingly, extraction cases have again seen resurgence since the late 1990s, reflecting evolving philosophies in orthodontics and patient-specific treatment planning. X Tooth size – Arch length discrepancy (TSALD) – is a fundamental concept in orthodontic diagnosis and treatment planning. It refers to the difference between the amount of space available in the dental arch (arch length) and the amount of space required to accommodate all teeth in proper alignment (sum of mesiodistal tooth widths). X Positive discrepancy – When the available arch length is greater than the total tooth material, leading to spacing between teeth. X Negative discrepancy – When the available arch length is less than the total tooth material, resulting in crowding. Classification of Arch Length–Tooth Size Discrepancy Arch length–tooth size discrepancy (crowding) can be classified according to its severity as follows: 1. Mild Crowding Discrepancy: 1–3 mm Characteristics: X Usually observed during the transition from primary to permanent dentition. X More commonly affects the anterior region. X Presents as slight buccolingual displacement or rotation of one or more teeth. 2. Moderate Crowding Discrepancy: 3.1–5 mm Characteristics: X More pronounced irregularity in the alignment of the incisors. X Arch length deficiency is evident but can often be managed with non-extraction approaches (e.g., interproximal reduction, arch expansion). 3. Severe Crowding Discrepancy: ≥ 5.1 mm Characteristics: X Significant lack of space in the dental arch. X One or more teeth are often displaced completely outside the arch form. X Management frequently requires extraction therapy or significant spacegaining procedures. To extract or to expand Whether to “extract or expand” teeth to correct crowding depends on the severity of the crowding and the patient’s specific dental and skeletal characteristics. Expansion is preferred for mild to moderate crowding, especially when there’s sufficient bone and no risk of soft tissue damage, as it increases arch perimeter and avoids extractions. Extractions are considered for severe crowding (>6-7 mm) or when expansion isn’t a viable option, creating space to align and stabilize the teeth. Role of Facial Profile in Extraction Decision-Making Facial profile plays a crucial role in determining whether extractions should be included in an orthodontic treatment plan. Opponents of extractions argue that removal of teeth can lead to a “dishedin” appearance of the face, potentially compromising facial esthetics. In contrast, proponents believe that extractions can enhance facial harmony by reducing dental and soft tissue protrusion, resulting in a more balanced profile. Rushing et al. conducted a study on the effects of orthodontic extractions on facial profile and reported that most dental surgeons and orthodontists were unable to determine, without a direct clinical examination, whether extractions had been performed. These findings were supported by Stephens et al. and Erdinc et al suggesting that the impact of extractions on profile may often be subtle and clinically unnoticeable. Based on severity of crowding For moderate arch length discrepancies (≤ 5 mm), treatment planning should be considered based on multiple factors, including facial profile, incisor position, degree of crowding, and the amount of keratinized gingival tissue. Straight facial profile: X When the lips and incisors are wellpositioned anteroposteriorly or slightly retrusive, limited dental arch expansion can be used to gain the necessary space for alignment. Protrusive incisors: X Expansion is not recommended in cases where the incisors are already protrusive, as this may worsen the profile and compromise esthetics. Clinicians should carefully evaluate the relationship between crowding, incisor inclination, and facial profile, as these factors are interconnected and must be addressed holistically to achieve stable, Dental crowding: to extract or expand?? Dr Geoff Hall By Dr Geoff Hall, BDsc (Melb) Cert Orth (Uni of Penn) MRACDS (Orth), Diplomate – American Board of Orthodontics (ABO)
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