Let’s review the intermaxillary elastics in orthodontics

INTRODUCTION

Orthodontics is a specialized branch of dentistry that focuses on the prevention, intervention, diagnosis, and treatment of dental and facial irregularities. One common tool used in orthodontics is intraoral elastics. Intraoral elastics, also known as rubber bands, are an integral part of orthodontic treatment. They are used to apply forces to the teeth and jaws, helping to correct misalignment and achieve proper alignment.^[1] These elastics are typically made of latex or synthetic materials and are available in various sizes, colors, and strengths.^[2] Originally, latex was the only material used to make the elastics, which are still the most popular today. Nonetheless, artificial orthodontic elastics are currently being manufactured, providing a choice for patients who experience latex allergies.^[3-8]

The intraoral elastics in orthodontic treatment are used for achieving desired tooth movement and maintaining anchorage during treatment and they play a crucial role in orthodontic treatment by exerting forces on the teeth and jaws to correct malalignment.^[9] Elastics are commonly used in conjunction with braces or other orthodontic appliances to help move the teeth into their desired positions.^[10] They can be attached to brackets on the teeth or to hooks on orthodontic wires, depending on the specific treatment plan. These elastics work by applying a continuous force on the teeth, gently guiding them into the desired position.^[11]

Using intraoral elastics as an alternative to surgery offers a non-invasive approach that many patients prefer. This can be particularly beneficial for those who are averse to surgical procedures. In addition to avoiding surgery, orthodontists may use alternative treatment modalities such as Class II elastics, extractions, extraoral traction, orthodontic distalizers, temporary anchorage devices (TADs), and fixed functional appliances to address malalignment and achieve the desired results.^[12] Elastics have a number of drawbacks, including the need for patient cooperation, deterioration in the oral environment, and side effects such as occlusal plane asymmetries, root resorption, allergic reactions, and dental rotations.^[4,13-23]

MATERIALS AND METHODS

An extensive search was done among the orthodontic literature with the use of PubMed, Google Scholar, and Research Gate using the keywords “Elastics AND orthodontics,” “Intraoral elastics OR Orthodontic elastics.” The included articles were those which reported different types of connections used for elastic placement and various types of intraoral elastics.

HISTORICAL PERSPECTIVE

The use of elastics is believed to have stemmed many years ago when the Mayans and Incans utilized natural rubber for different purposes. Natural rubber is considered the first-ever elastomer (rubbery material) that can return to its original shape even after extended periods of stretching. Charles Goodyear, an American engineer and chemist, created the vulcanization process. When the vulcanization process became more popular, more people and businesses started using natural rubber.^[24] At the Columbia Dental Congress, Calvin Case talked about using intermaxillary elastics. Nonetheless, the use of intermaxillary elastics is credited to Henry A. Baker. The Baker anchorage was first used by Henry A. Baker in 1893. It involved using intermaxillary elastics with rubber bands.^[25-27] Dr. Calvin Case, an orthodontist states that he was the first clinician to use intermaxillary elastics. However, the father of American orthodontics, Edward Angle, along with other colleagues, believed that it was Dr. Baker who pioneered elastics in orthodontics and not Dr. Case.^[28,29] He presented the method to the New York Institute in 1902.

However, more importantly, there was a problem with natural rubber. Its elasticity decayed within a short span of time because when the elastics stay inside the oral environment, the rubber would begin imbibing water. As a result, the elastics deteriorated swiftly. It was later decided that latex elastics should replace natural rubber in the early 1900s. Around the 1960s, synthetic elastics were developed and soon became the choice material for orthodontics.^[30,31]

ELASTIC BANDS

Elastic bands are manufactured by slicing rubber tubes of different lumen and wall thicknesses. The lumen of the band and its wall thickness determines the force value when stretched. Within each size of the lumen, there are three types of bands – light, medium and heavy; in terms of their force value [Figure 1]. According to lumen size – the lumen of the elastic band is usually expressed in parts of an inch. For example – a 3/8 inches rubber band means that the lumen of the band is three parts of the eight parts of an inch.

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Figure 1:

Lumen sizes of elastics.

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PRE-STRETCHING OF ELASTICS

Wong suggested in 1976 that the elastomeric materials be pre-stretched to 1/3^rd of their length. This procedure will increase the length of a material. If the material is overstretched, a slow set will occur but will go back to the original state in time. If the material is overstretched to near breaking point, over and over again, permanent plastic deformation will occur. This means that the initial force may come to an effect during a pre-stretched process. Hence, when it is in use, it will give a more stable force. ^[25,32]

TYPES OF INTERMAXILLARY ELASTICS

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Figure 2:

(a) Class II; (b) Class III; (c) anterior elastics; (d) cross elastics; (e) triangular type 2; (f) triangular type 3; (g) delta; (h) m elastics; (i) sling shot; (j) midline; (k) box elastics; and (l) intermaxillary elastics for aligners (modified from Farret, 2023).

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ELASTIC FORCES AND FORCE DECAY

In Class II and Class III elastics, the current review and research literature suggest that using light force can be gained by wearing elastics of size 3/16 inches in diameter.^[35-37] Forces advised by clinicians were (1–2 ounces (oz),^[38,39] 2.5 oz,^[40] 3.5 oz,^[41] 4 oz,^[35] and 6 oz^[37]).^[42] The rubber bands show a decay of force within 1^st h of their placement in the mouth. About 20–25% of force decay is seen within 24 h^[43] of which 15% occurs within 1^st h. It concludes that the elastics should be changed every day for optimum force delivery to get the desired effect. Force values do get affected by salivary contents and pH, bacteria, forces of mastication, and various foods and temperatures, which cause the rubber to break down due to the formation of a knotty tearing mechanism in its structure, causing it to swell up and, hence, resulting in force decay.^[44]

BIOCOMPATIBILITY OF ELASTICS

CLINICAL IMPLICATIONS

A number of variables are responsible for the effective tooth movement while using intermaxillary elastics, namely, volume and density of bone, patient’s growth phase, previous trauma or current pathology, length, number, surface area of roots, and their individual anatomy. All these can alter the force levels along with modifications of placing the elastics such as single elastic use, double elastics usage, or to increase the initial stretch, adding an extra tooth in the group. Some articles found that daytime wear of elastics has a greater degree of vertical component due to the stretching of the mouth in a range of 10–25 mm, while at night, both horizontal and vertical components are approximately equal. The force levels also depend on the required tooth movement and its direction. Maintenance of hygiene is a very important aspect of using elastics as it is proven in the literature that latex causes a high amount of hygiene issues due to the accumulation of plaque; hence, changing of elastics every day or every 24 h.

CONCLUSION

Without any doubt, intermaxillary elastics are the most important aspect of orthodontic treatment due to their wide possibility and versatility of biomechanical application. However, clinically, it is most important to have a thorough knowledge of the desired effects and of the possible negative effects that are normally associated with the biomechanics using elastics so that the results are obtained as planned and desired by the orthodontist.