Myths and realities in orthodontics

The development of a novel Orthodontic Alignment Index and its use to evaluate the effect of residual overjet on the stability of the alignment of the maxillary anterior dentition

BACKGROUND

It is thought that achieving a normal overjet may help to stabilise the alignment of the maxillary anterior dentition. Little's Irregularity Index is limited in assessing discrete post-orthodontic changes, fails to account for reciprocal rotations and is not sensitive to dental changes in three planes. A more holistic tool for the assessment of post-treatment change is therefore required.

AIM

To compare the post-treatment stability of maxillary anterior dental alignment in subjects treated either to a Class I incisor relationship or an increased overjet (> 4 mm) following fixed appliance-based orthodontics using a novel measurement tool.

MATERIALS AND METHODS

The Orthodontic Alignment Index (OAI) was developed and validated using a panel of 63 raters. The new index accounts for a range of weighted features including contact point displacement, spacing, reciprocal rotations, inclination, angulation and vertical discrepancy. A retrospective cohort study was undertaken at the Institute of Dentistry, Queen Mary University of London. Recruitment took place over a 4-year period. All participants had removable retainers in the maxillary arch only. The stability of maxillary anterior teeth was assessed using Little's Irregularity Index (LII) and the OAI. Subjects were recruited at least 12 months following completion of dual-arch fixed appliance-based treatment.

RESULTS

Eighty-two participants were included with a positive correlation observed between LII and OAI at the 12-month post-treatment review with a 1-mm increase in LII associated with a 2-point increase in the OAI (P < 0.001). Limited relapse was observed in both groups: normal overjet group (OAI = 1.28; LII = 0.52); residual overjet group (OAI = 0.88; LII = 0.47). Median regression analysis failed to identify a significant association between an increased overjet at debond and the alignment of the maxillary anterior segment when assessed with OAI (P = 0.389) and LII (P = 0.577). Furthermore, age, gender, extraction protocols and retention regime were not predictive of post-treatment change.

CONCLUSIONS

Using a novel index (OAI) and LII, there was limited post-treatment relapse in alignment of the maxillary anterior dentition over a 12-month period. Based on this retrospective evaluation, achieving a normal overjet at the end of treatment may have little bearing on the post-treatment stability of maxillary anterior alignment at 12 months.

Orthodontic treatment planning: can we plan for stability?

Careful orthodontic treatment planning should involve the delineation of clear treatment objectives within each dental arch. Treatment planning decisions are underpinned by aesthetic goals, dental health considerations and the prospect of stability, with these factors often competing. There is also a near-universal acceptance of the requirement for some form of retention. A novel hierarchy of orthodontic stability is proposed. As further evidence emerges and technical refinement continues, it is likely that this will undergo further adaptation. Ultimately, however, this knowledge will ensure that our understanding of the merits of orthodontic intervention, allied to the burden of retention, can be clearly presented to prospective orthodontic patients.

'What has been your experience of providing short-term orthodontics?'--A pilot survey of GDPs in East Sussex

Short-term orthodontics (STO) aims to enhance a patient's smile by aligning their anterior teeth. It is considered a quicker alternative to conventional orthodontics and less destructive than veneers. As such, it has recently gained much popularity in cosmetic dentistry worldwide. STO is provided almost exclusively by general dental practitioners (GDPs), however, the current literature on this subject focuses largely on the opinions of orthodontists and cosmetic dentists, respectively. The aim of this paper, on the other hand, is to examine the opinions of GDPs and what experience they have had of providing STO. It concludes that GDPs performing STO in East Sussex have expressed a wish to receive more teaching and support from their local orthodontists. It also suggests a need for orthodontic professional bodies to issue guidelines on case selection for STO in order to assist GDPs in recognising which malocclusions are beyond their scope of practice.

The Limitations of Short-Term Orthodontics and Why We Still Need Specialists – A Review of the Current Literature

Short-term orthodontics (STO) serves to align anterior teeth. It has become popular in cosmetic dentistry as an alternative to destructive veneers and lengthy conventional orthodontics. The aim of this article is to raise awareness of the clinical limitations of STO and highlight some of the difficulties encountered with orthodontic retention. It also gives an overview of accredited training available to dentists who wish to develop their orthodontic skills. Clinical relevance: Greater awareness of the clinical limitations of short-term orthodontics will aid GDPs in appropriately selecting their cases and obtaining informed consent from patients. In addition, the article serves as encouragement for those GDPs wishing to develop their orthodontic skills and pursue further accredited training.