History of interceptive orthodontics

History of interceptive orthodontics

Interceptive orthodontics is not a new idea. Archeological data show that Egyptian mummies had crude metal bands wrapped around individual teeth. It is speculated that, with the help of catgut, management of dental crowding was attempted. The first description of teeth irregularities was given by Hippocrates about 400 BC (460–377 BC). Pliny the Elder (23–79 AD) was the first to suggest a mechanical treatment technique by filing elongated teeth to bring them into proper alignment.¹² The techniques of Pliny the Elder and others remained unchanged for a long time.

Early modern era

During the period 1600–1800, there was some progress in terms of interception of developing malocclusion. In 1619, Fabricius first described the prophylactic extraction of premolars in cases of crowding. He also attempted to treat ‘protruding chins’ by extraction of the lower first molars shortly after eruption. The first reported attempt to correct a posterior crossbite in the developing dentition with an appliance was by Pierre Fauchard (1678–1761) in 1728 in France, who is considered the ‘father of orthodontics’.¹³ He used a precious metal expansion appliance to eliminate a mandibular displacement. Fauchard's appliance was adopted in America and modified by Edward Angle in the 19th century. This basic design is still used nowadays under different names such as the Jokey arch, Irish arch or auxiliary archwire.¹⁴

In 1757, Etienne Bourdet, the French king's dentist recommended serial extractions to relieve crowding in the developing dentition.¹⁵ Serial extractions were again reported in the 17th century by Robert Bunon in his book ‘Essay sur les Maladies des Dents’.¹⁶ This approach was one of the few orthodontic modalities described at that time. It later became a popular approach owing to the limited efficiency of orthodontic appliances and their expense. John Hunter (1728–1793) was an important dental innovator in the 18th century who first presented the benefits of using the leeway space in the late mixed dentition. He wrote that ‘milk molars are bigger than premolars but milk front teeth are smaller than permanent teeth’.

Late modern era

In the early 19th century, European practitioners had important roles in the advancement of interceptive orthodontics. In 1803, Joseph Fox condemned the effect of premature extractions of primary teeth. He encouraged maintaining them and using space maintainers if they were lost prematurely. During the same period, chincups were being used in Germany by dentist Friedrich Christoph Kneisel (1797–1847) to treat Prince Charles of Prussia. The French dentist, Christophe-Francois Delabarre (1787–1862) used threads and wooden wedges to separate impacted teeth (in particular, impacted upper first permanent molars). In 1841, this molar disimpaction approach was further developed by Alexis Schange when the vulcanization process became popular, allowing rubber bands to be used, and the effects of thumb sucking and tongue thrusting habits and their role in developing a malocclusion were described by Rodrigues.

In early 19th-century America, pioneers were working at the same pace as their European peers to enhance and develop early orthodontics. Norman Kingsley (1829–1913) described the use of the headcap for early orthodontic treatment of an increased overjet. In 1843, Edward Maynard was the first dentist to report using gum elastics wired to teeth as a fixed functional appliance at an early age.¹³ Amos Westcott used a telescopic bar wired to the teeth and a chincup on his Class III patients as an interceptive measure. CR Coffin, in the late 1850s developed a new removable expansion appliance using a W-shape spring-action piano wire and a vulcanite plate, which was named the Coffin spring.¹⁷ In the late 19th century, the use of space maintenance was described for the first time following Davenport's report in 1887 of space loss secondary to premature loss of deciduous teeth.¹⁸ Not all interceptive approaches, however, have been successful. Leonard Koeker (1728–1850) and Wilkinson, in the 1940s, suggested the elective extraction of all first permanent molars to reduce permanent teeth crowding, believing that first molar extraction at any period before the age of 12 years would relieve anterior crowding by the principle of teeth growing backwards. This approach has now largely been abandoned due to the absence of sufficient evidence and the significant traumatic effect of extracting the first molars.

20th century

During the early 20th century in Europe, efforts were focused on stimulating jaw growth in growing children following the introduction of Robin's monobloc in 1907 and Andersen's activator in the 1930s. Hundreds of research papers, mainly retrospective investigations, documented the effects of dozens of different functional appliances in treating developing malocclusions. The use of functional appliances in the early mixed dentition peaked in the 1940s due the dominance of removable appliances over expensive fixed appliances. European dental practitioners were more experienced in using removable appliances compared with their American peers and, until the early 21st century, it was believed that functional appliances grew jaws: a large proportion of clinical successes were attributed to an increase in mandibular growth, rather than dental compensation.

In the same period, Edward Angle developed his first orthodontic appliance. Angle was preoccupied with facial aesthetics and maintaining an ideal profile, which led to shift towards corrective non-extraction orthodontics. He was not a proponent of interceptive orthodontics and suggested that the use of headgear in the interceptive treatment of class II malocclusions was not a good intervention. He believed that intra-oral class II elastics could be more effective. It was not until 1936 when Oppenheim re-introduced early extra-oral traction devices that occipital headgear became popular again. Charles Tweed and Raymond Begg, two of Angle's former students criticized Angle's philosophy of non-extraction and simultaneously revised their therapies after being dissatisfied with the extent of relapse noted in Angle's non-extraction cases. This caused a resurgence of the serial extraction philosophy among dentists.

The first person to formally describe the term ‘serial extraction’ and the thinking behind it was Birger Kjellgren who published his paper in the mid 1940s.¹⁹ Later, the American orthodontist, Haynes Nance, popularized the idea of serial extraction and is considered the father of modern serial extraction philosophy. Several terms have been used to describe serial extractions, such as ‘progressive extractions’ (Palson) ‘planned’ extractions' (Nance) and the Swiss alternative term ‘guidance of eruption’.^20,21,22 The idea of serial extraction and the timely removal of primary teeth was further tested, not only to treat primary crowding, but also to alleviate potentially impacted teeth. Extraction of primary canines was tried as an interceptive method to treat palatally displaced upper permanent canines, and resolve the associated complications of root resorption of adjacent teeth.²³ This approach was initially opposed by many clinicians who found minimal or no benefit in undertaking this interception; however, it became one of the most accessible and cheap treatment options during WWII.^24,25

The universal views about interceptive orthodontics and, in particular, early orthopaedic appliances were further developed in the mid-20th century. The introduction of cephalometrics in orthodontics provided a better understanding of skeletal and dental changes, which showed that elastic traction had mainly dento-alveolar effects with little influence on disproportionate skeletal growth patterns. Advancements in the understanding of growth led to the re-introduction of headgear as a molar distalizing device, and as maxillary growth-restricting appliances.^26,27 In the 1950s and 1960s, advances in dental technologies, with the provision of cost-effective fixed appliances, led to a move against interceptive approaches among orthodontists.²⁸ Despite this, a number of noted practitioners proposed their own version of serial extraction involving different sequences for the extraction of the primary canines, primary first molars and first premolars (Tweed, Nance, Dewey and others).²⁹ These developments were finally supported by some tenuous evidence, when a series of case reports was published reporting the effectiveness of the removal of primary canines to treat impacted teeth as early as a dental age of 8 years.^30,31,32,33

In the late 1970s several appliances were described to aid space maintenance, such as the band and loop, removable appliances, partial dentures, lingual arches, transpalatal arches, distal shoes, or even the bonding of rigid wires across spaces. These approaches subsequently fell out of favour owing to their complexity and the need for multiple patient appointments. However, they have re-emerged following a 2010 systematic review that showed that a lingual arch is an effective approach to maintain molar position and prevent incisor tipping.³¹

Current recommended principles of early orthodontic interventions

A historical perspective of an area helps us to develop our current thinking. It is clear that interceptive orthodontics had an important part to play in managing orthodontic malocclusion. It is interesting that its popularity cannot be attributed to its evidence, but to outside factors that impact on the clinical decision. The quality of orthodontic appliances, the desire for a better smile at a young age and public acceptance for financing orthodontic treatment have all influenced the use of early treatment.

Today, we have highly efficient appliances, which are relatively cheap and easy to use, often publicly funded, driving the popularity of orthodontic treatment. This treatment delivery has influenced the acceptance of interceptive techniques, for which there is a weak evidence base. Nevertheless it does have a role to play, particularly where complex fixed appliances are not accessible to the patient. A developing malocclusion is a dynamic process and there is rarely a single approach to treatment. Before indicating any interceptive measures, informed consent demands that the patient and practitioners fully understand the reasons behind the treatment. Factors including the patients wishes, psychosocial position, aspirations and ability to comply with complex orthodontic appliances must be taken into account when deciding the best treatment plan for that individual. Interceptive orthodontics is just one approach that should be considered in an overall treatment approach. Following this philosophy, there are a variety of popular interceptive procedures that are commonly practised today.

Interceptive measures to manage the effects of digit-sucking habits

Effective early interventions of digit habits to avoid malocclusions, such as anterior open bites, crossbites and increased overjets, make subsequent orthodontic treatment much easier. Habit cessation by means of reminder therapy with the help of splints, a glove or a foul-tasting substance, is a simple, but effective, measure to eliminate prolonged sucking behaviour. It is important to note that any type of reminder therapy must be undertaken with the child‘s awareness and willingness, and not used as punishment.³² If reminder therapy fails, appliance therapy in the form of removable or fixed habit breakers should be implemented. Removable appliances usually have a positive effect within a few months, whereas fixed appliances (eg a palatal crib) can ensure complete and immediate habit cessation and are, therefore, more effective.³³ Both should be left in place for at least 6 months, especially if the digit-sucking habit continues through the establishment of the permanent dentition.

Early extractions

Although any tooth can be positioned ectopically, the upper canines are most commonly affected in the developing child. A common management protocol is the interceptive extraction of primary canines to improve the position of palatally ectopic canines.^34,35,36 This, however, requires careful assessment of the position of the canine vertically and towards the midline to ensure the effectiveness of this intervention. Early deciduous canine extraction is also beneficial for individuals with insufficient anterior space for the accommodation of fairly well positioned lateral incisors. However, it usually does not resolve the underlying space problem, and is most likely to result in later crowding during the development of the permanent dentition.³⁷ The great advantage for this is the maintenance of the anterior aesthetics throughout the establishment of the permanent dentition, but it also reduces the length of time that the later comprehensive orthodontic treatment will take.

Preserving leeway space

Space loss resulting from the early extraction of second deciduous molars is usually attributed to mesial drift of the molars and can result in complete loss of the second premolar space if not managed appropriately. To prevent the loss of arch length in cases of premature loss of deciduous teeth due to caries, trauma or congenital absence, preservation of the leeway space, with either removable or fixed space maintainers, is recommended. As compliance with removable appliances is an important factor in preventing unnecessary arch length loss, fixed lingual arches have shown greater effect in space preservation through controlling the mesial movement of molars, and preventing lingual tipping of the incisors.³⁸

Anterior and posterior expansion

The aetiology and severity of the transverse problem play an important role because maxillary expansion can be achieved with different types of appliances. The aim of early interventions is to prevent any adverse effects on growth by resolving any functional disturbances (eg unilateral crossbites), unlocking the occlusion and establishing an improved environment for further development by means of expansion.³⁹ Minor dental arch asymmetries, and crowding attributed to narrow dental arches, can often be managed early with inexpensive removable expansion appliances.⁴⁰ These appliances also depend on compliance, and are not adequate for all patients. Management of severe and pronounced arch constrictions require correction by increased skeletal expansion, rather than just dental tipping. This is usually attempted with fixed, quadhelix or rapid maxillary expansion appliances, before full maturation of the maxillary suture.

Early Class II

The primary treatment objective of early Class II treatment is to correct a severe anteroposterior malocclusion characterized by a sagittal jaw discrepancy of more than 6 mm. The aim is to take advantage of the growth potential early, which helps to address the skeletal problems and in turn, decreases the risk of trauma to the upper incisors.⁴¹ Pronounced overjet reduction has also shown to have a positive effect on a patient's psychological state in cases where teasing is experienced.⁴² Patients at the age of 9–10 years are often very compliant with early treatment, which makes treatment much easier. It is important to note that early functional treatment does not necessarily prevent later orthodontic treatment; however, it can simplify it by reducing the time and difficulty of the second phase, avoiding later extractions or even surgery.

Early Class III

Anterior crossbites are often associated with dental and periodontal problems of the lower labial teeth. Early intervention with protraction facemasks for patients with a maxillary deficiency has shown to positively improve the sagittal skeletal and dental relationship if addressed at the appropriate time.⁴³ Additional incorporation of a chincup is believed to retard or redirect the growth of a prognathic mandible. Achieving a positive overjet and a better occlusal relationship early, provides a favourable environment for future growth.⁴⁴ In order to maximize orthopaedic treatment effects and stability of early treatment, maxillary protraction should be carried out as soon as possible, ideally before complete suture ossification of the maxillary complex.

Conclusion

Taking a historical perspective helps us to understand why the treatment modalities we use today have been developed. It also allows us to reflect on our practice and introduce new ideas to further improve what we already know. It is difficult to provide good evidence on early interceptive measures, as many of the current approaches are based on clinic practice and experience rather than from an evidence base owing to the ethical dilemmas of providing control groups, or withholding treatment to patients in need. Interceptive orthodontics can help to reduce the complexity and the cost of the comprehensive orthodontic treatment. The role of the GDP is crucial in identifying any developing problems or abnormalities in a child because they are usually the first to see the patient. There is clear evidence that malocclusions can be corrected and prevent future complications with relatively simple, early interceptive means, such as interceptive extraction or the correction of crossbites in the developing dentition. Interception, however, does not only depend on the patient's age: every patient needs to be evaluated individually because chronological age and dental age do not always coincide. Both the patient's and their parents' agreement must be gained before undertaking any procedure that cannot have a predicted outcome. Interceptive procedures, by their very nature, are often based on clinical judgement and need careful follow-up. Informed consent is crucial to the process, as is a full understanding of the aspirations of the patient and their parents. This approach takes experience, and a complete understanding of the growth and development of the dentition. For most GDPs, it can be a daunting task to commit a patient to irreversible procedures, such as early extractions, when the final outcome may be many years in the future. It is important, therefore, that there are close relationships between GDPs and specialist orthodontists and paediatric dentists to ensure that opportunities are not missed and mistakes are not made. The second article in this series presents ‘where we are now’ to help practitioners understand what options are available. Interceptive practice is constantly being reviewed and our current practice should be seen as a link to the future, when greater understanding and more data can give us more insight into the management of the developing dentition. The better this is managed, the less complex the orthodontic treatment will need to be for each patient.