One key technique employed in clear aligner treatments is interproximal reduction, a process that plays a crucial role in achieving optimal results. This article aims to shed light on its importance and understanding why it is performed.
What is IPR?
IPR also known as interproximal reduction or stripping is a clinical procedure that involves the creation of small spaces between the teeth. The process is done by carefully removing an amount of the proximal enamel thickness where adjacent teeth meet reducing the teeth width, enabling easier movement and facilitating their alignment. It is irreversible, and therefore careful examination before the procedure is mandatory. While being a frequently performed procedure, it is not for every orthodontic case[1].
Why and when is interproximal reduction performed?
It is sometimes necessary in clear aligner treatments, as well as in fixed appliances like braces, to straighten crowded teeth. By creating additional space, it allows the aligners to gradually shift the teeth into their correct position. Interproximal enamel reduction has appeared as a feasible alternative for extraction of permanent teeth, effectively adjusting the tooth size discrepancy (known as Bolton discrepancy)[2], without compromising the integrity of periodontal and dental tissues[3]
Bolton’s tooth size discrepancy is the main reason that IPR is used to manage orthodontic patients[4]. In certain cases such as overlapping teeth, tipped teeth, severe rotations and small crowns it becomes challenging to perform IPR from the beginning without causing harm to adjacent teeth. In order to accomplish the reduction without any damage, it is necessary to wait until the teeth have achieved a better alignment in an advanced step, or if it is possible perform IPR on posterior teeth.
How much IPR can be done?
The total amount of IPR to be performed as well as its timing during the treatment is carefully pre-planned by the doctor and the laboratory.
Using the Bolton’s ratio, it is possible to calculate the predicted fit of the teeth following alignment[5]. The maximum amount of IPR that is clinically recommended to be performed is 0.5 mm per anterior contact point, and up to 1 mm per posterior contact may be safely removed using IPR[6]. These recommendations preserve the amount of enamel, ensuring that teeth maintain their health and are entirely free from any sensation of pain.
What are the tools that can be used to perform IPR?
1. Manual abrasive metal strips
2. Manual abrasive strips with handle
3. Diamond-coated stripping burs
4. Diamond discs
How do you measure the amount of IPR?
IPR gauges or keys are one of the tools commonly used to ensure that the correct spacing has been achieved.
What are the advantages and risks of IPR?
|
Advantages |
Risks |
|
Effective in resolving crowding |
Hypersensitivity |
|
Not harmful to the hard tissues or soft tissues of the teeth If the technique is utilized correctly |
Dental pulp damage |
|
Change the tooth’s dimensions, restore a better morphology and improve aesthetics |
Increased formation of plaque |
|
Reduction of black triangles |
Increased risk of caries |
|
Correct occlusion can be obtained by reducing Bolton’s disharmonies |
Possible periodontal diseases |
|
Alternative to dental extractions |
Alveolar bone loss |
|
Reduction in treatment time |
|
[1] Lapenaite and Lopatiene, “Interproximal Enamel Reduction as a Part of Orthodontic Treatment.”
[2] Lapenaite and Lopatiene.
[3] Hariharan et al., “Evaluation of Interproximal Reduction in Individual Teeth, and Full Arch Assessment in Clear Aligner Therapy.”
[4] Meredith et al., “Interproximal Reduction in Orthodontics.”
[5] Meredith et al.
[6] Meredith et al.