Although for many patients it is primarily an aesthetic concern and a source of self-consciousness, from a medical point of view this problem is far more serious. An insufficient amount of space in the upper or lower jaw is a pathological condition that impacts oral health and hygiene.
Crowded teeth create hard to clean niches, becoming an ideal environment for decay causing bacteria and leading to chronic gum inflammation. For this reason, in many cases straightening teeth is a medical necessity rather than a cosmetic procedure.
At our Polish medical and dental clinic in London, the team of highly qualified specialists combine many years of clinical experience with a modern approach to dentistry. We focus on precise diagnostics and treatment plans tailored to individual needs, because we know that every bite requires a different strategy. We treat effectively, aiming to preserve natural teeth and ensuring patients are comfortable at every stage of treatment.
What causes dental crowding?
A lack of space in the dental arch is a complex problem. Contemporary orthodontics understands it as an interaction between genetic factors, civilisational changes, and environmental influences during a growth period.
Craniofacial evolution
Anthropological studies show that human skeletal system has undergone significant transformations over thousands of years. A shift to a softer, more processed diet reduced the need for intensive chewing, which in turn led to an evolutionary reduction in size of the maxillary and mandibular bones. However, this process did not occur together with a reduction in the teeth number or size. As a result, there is a disproportion in modern population: teeth have retained their original dimensions, while the bony base that should accommodate them has become significantly narrower.
Genetic factors
An important factor is inheritance of morphological traits. A patient may inherit tooth size from one parent (e.g. large, wide crowns) and jawbone dimensions from the other (e.g. a delicate facial structure). This genetic disproportion leads to a situation in which the total width of the teeth exceeds the available space in the dental arch, making correct alignment physically impossible without specialist intervention.
In addition to genetics, acquired factors during the developmental period play a key role in bite development, as they can disrupt normal facial bone growth.
Mouth breathing
Physiological breathing takes place through the nose. When breathing this way, our tongue rests against the palate, putting pressure and stimulating its transverse growth (widening of the upper jaw). In cases of chronic airway obstruction (e.g. allergies, enlarged adenoid), a child is forced to breathe through the mouth. Tongue drops to the floor of the mouth, and the upper jaw, deprived of natural support, becomes narrow, getting a characteristic shape (so-called gothic palate). In such constricted arch, there is insufficient space for erupting permanent teeth.
Premature loss of primary (baby) teeth
Baby teeth play an important role in maintaining proper space for permanent teeth. Their premature loss, most often due to decay, leads to issues within the dental system and may hinder the correct eruption of permanent teeth. After a primary tooth is lost, adjacent teeth tend to drift towards the resulting gap. This leads to loss of space intended for the permanent tooth, forcing it to erupt outside the arch or causing it to become impacted in the bone.
The role of third molars (wisdom teeth)
Influence of wisdom teeth on crowding of the anterior teeth in young adults (late crowding) is the subject of scientific debate. Although the eruptive force of third molars may put some pressure on the dental arch, current research suggests that this is not the sole causative factor. Physiological residual mandibular growth and the natural tendency of teeth to move forward with age also play an important role. Therefore, prophylactic removal of wisdom teeth does not always guarantee long-term stability of orthodontic treatment results.
Why can dental crowding be dangerous to health?
From a dental perspective, incorrect tooth alignment within the arch is a pathological condition that directly affects the condition of the entire stomatognathic system. Failure to undertake orthodontic treatment can lead to a number of complications, which are far more complex and costly to treat later in life.
Impaired hygiene and periodontal disease
Primary clinical problem resulting from overlapping teeth is a severe limitation in maintaining proper oral hygiene. Even with flosses or irrigators, accessing all contact surfaces in a crowded arch can be impossible. This leads to accumulation of bacterial plaque (biofilm) and hard deposits in inaccessible areas. Chronic presence of pathogens causes gingival inflammation (gingivitis), manifested by bleeding and swelling. Untreated inflammation may progress to periodontitis, leading to destruction of the ligaments supporting the tooth in the socket and resorption of the alveolar bone.
Increased risk of decay
Areas of tight contact between crowded teeth are predisposed sites for decay development. Due to food retention and the inability to mechanically remove debris, enamel demineralisation occurs. Interproximal decay is difficult to detect at an early stage without radiographic imaging, and its conservative treatment often requires significant removal of healthy tooth tissue to access the lesion.
Traumatic occlusion and pathological tooth wear
Correct bite is characterised by even distribution of chewing forces across all teeth. In cases of crowding, this balance is disrupted. Some teeth, protruding beyond the arch line, are subjected to excessive loads during occlusion (so-called traumatic contacts). This leads to mechanical damage such as enamel cracks, chipped incisal edges, and pathological wear of cusps (attrition). These overloads may also result in cervical wedge-shaped defects (abfractions), which are often mistakenly diagnosed as the result of overly aggressive brushing.
Gingival recession and damage to supporting structures
When a tooth erupts outside the dental arch (most commonly canines or lower incisors), it is often displaced beyond the alveolar bone. In such cases, buccal bone plate covering the root is extremely thin or absent altogether (dehiscence). This leads to recession of the gum, exposing sensitive tooth neck and impacting smile aesthetics. Teeth positioned outside the arch are also much more susceptible to loss of stability if periodontal disease develops.
How can modern orthodontics help with crowded teeth?
Contemporary orthodontics has moved away from the former paradigm in which lack of space in the dental arch almost automatically meant extraction of premolars. Today, preserving the full dentition is the priority, and treatment plans are based on precise biomechanics and use of the adaptive potential of bone. The goal is not only to align teeth but, above all, to achieve harmony between arch width and the bony base.
Transverse arch expansion
In cases of maxillary narrowing, the primary treatment method is expansion (widening the arch transversely). In children and adolescents, where the palatal suture has not yet fully ossified, fixed expansion appliances (e.g. Hyrax expanders) are used. These allow physical separation of the palatal bones, creating new bony space for crowded teeth.
In adult patients, where skeletal growth is complete, the possibilities for skeletal expansion are limited. However, modern aligner systems and self-ligating appliances allow for remodelling of the alveolar bone. Through appropriate force application, teeth can be tipped and their inclination altered, functionally and visually widening the dental arch and creating space for crowded incisors.
Distalisation of posterior teeth
Another space-gaining strategy is distalisation - moving molars and premolars towards the back of the mouth. By using skeletal anchorage (orthodontic mini-implants), orthodontist can precisely retract the entire posterior segment without causing unwanted protrusion of the anterior teeth. The space gained in the anterior region allows crowding to be relieved without tooth extractions.
Controlled enamel reduction
When the space deficit is small or moderate (usually a few millimetres), the standard approach is IPR (Interproximal Reduction). This involves precise mechanical reduction of enamel on the teeth contact surfaces (typically by 0.1–0.5 mm). The procedure is completely safe for tooth health, as it is performed within the safe thickness of enamel and does not affect dentine. The cumulative millimetres gained from several interproximal spaces provide sufficient room to rotate and align teeth correctly, while also improving contact point stability and crown shape.
Despite technological progress, in extreme cases of disproportion between tooth size and the bony base, tooth extraction (most commonly first or second premolars) remains the only solution for achieving a stable and functional bite. Today, however, the decision to extract is made only after thorough cephalometric analysis and assessment of the patient’s facial profile. The aim is to avoid a situation, where preserving teeth “at all costs” would lead to excessive incisor protrusion, deterioration of facial aesthetics (the “protrusive lips” effect), and gingival recession.
Wisdom teeth – are they always to blame?
Many patients believe that wisdom teeth are the main cause of sudden tooth crowding in adulthood. In reality, blaming them entirely is an oversimplification. Studies show that lower incisors can become crowded even in individuals who never had wisdom teeth. This is the result of natural ageing processes of the bite and minimal changes in mandibular structure that occur throughout life. Teeth naturally tend to drift forward over time, which is why removal of wisdom teeth alone does not guarantee that a smile will remain straight forever; retention after orthodontic treatment is crucial.
When is wisdom tooth removal necessary?
Extraction is decided upon in specific medical situations, not “just in case”:
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Risk to second molars – when a wisdom tooth grows at an angle and damages the root or enamel of the adjacent tooth.
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Inflammation– when a partially erupted tooth creates a gingival pocket where bacteria accumulate, causing pain and infection.
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Orthodontic planning – when the clinician needs to retract the entire dental arch to create space for crowded anterior teeth; wisdom teeth are then removed to provide the necessary manoeuvring space.
Dental crowding – summary
Dental crowding is a problem that goes far beyond aesthetics. It is a condition that have serious impact on oral health. Ignoring a lack of space in the dental arch leads to faster enamel wear, periodontal disease, and decay on contact surfaces that is difficult to treat. It is worth remembering that it is never too late for orthodontic treatment. Modern medicine offers a range of solutions that allow safe and effective expansion of the dental arch, restoring not only a beautiful smile but also proper chewing function which is one of the best investments in preserving your natural teeth into old age.
At our Polish clinic in London, we focus on full digitalisation of the diagnostic process, which translates into comfort and precision of treatment. Using a 3D intraoral scanner, we create an accurate digital model of the dentition at the very first visit. This allows our specialists to precisely calculate space deficiencies and plan treatment down to fractions of a millimetre. Our treatment philosophy prioritises preservation of the full dentition. We always aim for non-extraction solutions, using modern self-ligating appliances and invisible aligners that allow the dental arch to be expanded in a physiological and safe manner.
