Prevention, derived from the Latin word praevenire‚ includes measures, programs, and projects to prevent undesirable events or developments. In general, the term can be translated as “anticipatory problem avoidance.” Prophylaxis is derived from the Greek word προφύλαξις (prophýlaxis) and can be understood as guard, outpost, or protection, stressing the aspect of primary prevention. In medicine, dentistry, and, therefore, also orthodontics, prophylaxis mostly means concrete actions that are supposed to prevent the onset of a disease, eg vaccination or oral hygiene. Prevention is broader and describes a concept within which prophylaxis can be an integral part.

The majority of books and publications in the orthodontic literature deal with the diagnosis and often sophisticated treatment of malocclusions in order achieve harmonious static and dynamic occlusion. However, the prevention of malocclusion may be a more rational approach if possible. For this, an understanding of the etiology of malocclusions and malfunctions is crucial.

Etiology of malocclusion and malfunction as the basis of prevention

A number of explanatory models have been devised for the development of teeth and jaw malpositions and malfunctions.¹ The best known are the theory of the functional matrix and the servo system theory.^2,3 A combination of different theories, also considering the therapeutic consequences, was proposed by van Limborgh.⁴ Overall, an interaction of genetic, epigenetic, and environmental factors can be assumed.

This gives starting points for prevention, and also knowledge on processes such as craniosynostosis that can hardly be influenced and are, therefore, not susceptible to prevention. In contrast to this, deviations due to local or general environmental factors are to be treated with good prognoses and possibly even prevented. Also, tissues of the viscerocranium are more susceptible to interventions than those of the neurocranium (Fig 15-1).

Form follows function

The connection between form and function has been well known for a long time.^5,6 Especially during growth and development, these interactions are significant. An imbalance in the muscles of the tongue and cheek or lip, combined with respiratory function, chewing, and swallowing form the dentoalveolar complex in the development of the teeth and influence the position of the jaw.

So far, only a few specific forms of malocclusion have been genetically localized by genome-wide association studies (primary failure of eruption, Class III).⁷ A careful family history is essential, but the modeling influence of environmental factors (local and general) seems to predominate. The maxilla is more receptive to influences, and the primary goal of therapeutic or preventive interventions.⁸ Further investigations will be able to better describe the relationship between phenotype and genotype with regard to malocclusions.⁹

The beginning of orthodontic prevention

Some early publications in the orthodontic literature focused explicitly on the prevention of dental malocclusions. Salzmann¹⁰ coined the term “public health orthodontics.” In the 1950s, Schwarz recommended inter alia the following valid points for prevention to the general dental practitioner¹¹:

• (early) orthodontic examination of each child
• informing the parents
• stop habits and secure free nasal breathing
• register premature primary tooth loss or retention in time (better to avoid it)
• do not extract canines
• do not extract first molars.

After the significant decline in caries in recent years, secondary crowding caused by premature decay of the primary tooth is decreasing. On the other hand, Perkins¹² already saw the essential role of orthodontic prevention in the control of harmful habits: In a study of 8,864 German kindergarten and school-age children, in 57% of all children dental anomalies were found.¹³ From the primary dentition to the mixed dentition, this percentage increased from 42% to 60%. Only the open bite showed a tendency for improvement due to a decrease of muscular dysfunction.

A selection of possible approaches for prevention-oriented orthodontics is presented and relevant topics will be briefly explained in this context. The currently most important aspect regarding prevention and prophylaxis is putting existing knowledge into practice and avoiding the “tragedy of unused medical knowledge.”¹⁴

Breastfeeding, swallowing, and chewing

The influence of infant diet on orofacial development has been discussed for a long time. A comprehensive review by Sabuncuoglu¹⁵ outlines the evidence base: a cross-sectional study of 2,060 subjects found associations between breastfeeding less than 6 months and Class II development and, therefore, concluded that short or no breastfeeding time can be a cofactor in the formation of oral parafunctions.¹⁶ Narbutyte et al¹⁷ see a protective effect of breastfeeding on craniofacial development, such as posterior reverse articulation (cross bite) and open bite. Similarly, the frequency of occurrence of parafunctional habits appears to be reduced.¹⁸ After evaluating a birth cohort of 1,303 children, Peres et al¹⁹ concluded that 6 months of breastfeeding are an effective prevention strategy. Last but not least, a number of general medically relevant positive effects are attributed to breastfeeding, eg improved cognitive development and less diabetes and cardiovascular disease.²⁰ Due to the heterogenous study situation, research is still needed in this field.²¹ When the first primary teeth erupt at about an age of 6 months, additional feeding should be started aiming to transfer the sucking reflex into a proper chewing pattern. Chewing is considered to be an important modulating factor in the development of the dentition.^22,23 For instance, changes in craniofacial morphology were found in animal experiments depending on the chewing pattern.²⁴ To what extent this can be transferred to the development of human teeth is uncertain.

Habits and malfunctions

Hands and mouth are represented with large areas in the neocortex to enable differentiated perception and movement. This is why thumb sucking in embryonic development and early childhood is important for neural facilitation.²⁵ Even at these early stages, habits such as the handedness are preformed in this interplay.²⁶ For this reason, thumb sucking is still physiologic in the first year of life, whereas later on, deformation of the alveolar processes and changes in the position of the teeth may occur (Fig 15-2).²⁷ The close connection between form and function is the basis of the recommendation of early treatment of harmful habits. For example, Ramesh et al²⁸ found malocclusions in almost 60% of children with a persisting sucking habit at the age of 3 to 6 years.

The weaning of harmful habits can be done on different levels,²⁹ including nonapparative approaches such as sucking calendars, a therapeutic counseling by the dental practitioner, or myofunctional therapy. Apparently, removable appliances have proven most useful, eg plates with tongue crib against persistent sucking or oral screen plates against the insertion of the lower lip between the teeth. A cross-sectional study (489 children) found a negative influence of persistent sucking on the dentition even when using a pacifier.³⁰ Tongue dysfunctions, tongue pressing (Fig 15-3), cheek sucking, sigmatism, and other functional deviations are also closely linked with the development of the tooth position and should be treated myofunctionally early on, before the onset of structural changes. Later in teenagers, fixed appliances may be the therapy of choice (Fig 15-4).

Playing musical instruments

According to Strayer’s classification³¹ of wind instruments, Grammatopoulos et al³² studied occlusal parameters in 170 professional musicians. It could be shown that even intense playing of a wind instrument has no significant influence on the position of the anterior teeth in adults. However, in the developing dentition the intense playing of brass instruments involves the danger of developing lingual reverse articulation. With intensive playing of string instruments the risk of temporomandibular disorder increases, and this should be counteracted by physiotherapy and possibly bite ramps.³³ The playing of wind instruments can train the orofacial musculature and with the correct playing technique instruments such as horn or trumpet can be recommended as an adjunct therapy in cases with class III tendencies.³¹

Premature loss of primary molars and space maintainers

The maintenance of the leeway and molar space is conditio sine qua non for an undisturbed development of the dentition,³⁴ and evidence-based caries-preventive programs can almost completely avoid premature decay of the primary tooth.³⁵ In case of a premature loss of primary molars, the positive effects of space maintainers have been described and implemented in different appliances for a long time.³⁶ Still, the evidence base for the implementation of space maintainers is unsatisfactory, especially for first primary molars.³⁷ However, it is undisputed that migration due to premature primary tooth loss and subsequent secondary crowding can lead to a lengthy and expensive orthodontic treatment, sometimes with the extraction of permanent teeth (Fig 15-5).³⁸

Canine retention

Canines are the most frequently retained teeth, with a frequency of 1% to 2%, after the third molars.³⁹ Retention results in extensive and lengthy orthodontic and surgical therapy.⁴⁰

Ideally, a first examination for the maxillary canines should take place at the age of 8 to 9 years. This includes visual inspection, palpation, and x-ray diagnostics.⁴¹ In the case of apparent retention in situations where there is no crowding and Class I molar relation, the situation can be improved by extraction of the primary canines (Fig 15-6) at the age of 10 to 13 years.⁴² According to Power and Short,⁴³ in 62% of cases canine retentions can be averted. In the presence of transversal space deficiency, the combination of rapid maxillary expansion (RME) with extraction of the primary canine teeth can significantly improve the situation.⁴⁴

Unilateral reverse articulation

According to Tonni et al,⁴⁵ unilateral reverse articulation is effectively treatable in the mixed dentition. There are indications arising from possible consequences of an untreated unilateral reverse articulation on musculoskeletal functions and adjacent organ systems. For example, unilateral reverse articulation may be associated with diminished ocular motility,⁴⁶ and a connection between posture and malocclusion has been discussed.⁴⁷ The evidence base is contradictory: März et al⁴⁸ found no influence on the mandibular position due to posture, while other authors found correlations between malocclusions and reduced static body posture and an influence of occlusal changes on posture and spine.^49,50 Therefore, a less invasive, risk-free interceptive treatment for reverse articulation is recommended (Fig 15-7).

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