Orthodontics: Dentoalveolar Crossbites Quiz

Treatment of Transverse Malocclusions

• Transverse malocclusions affect the side-to-side relationship of the upper and lower jaws.
• Diagnosis involves identifying the underlying cause (maxillary deficiency, mandibular excess, or a combination).
• Classification includes posterior crossbite (bilateral, unilateral, monodental), scissor bite (bilateral, unilateral, monodental), and other types of transversal anomalies.
• Epidemiological data shows a prevalence of 1-2.3% in the general population and 48% in orthodontic patients for posterior crossbite.

Index

• The index includes topics like concept and classification, epidemiology, etiopathology (genetic factors, habits), diagnosis, treatment, and frontal radiographs.

Concept & Classification

• Maxillary deficiency is determined by alterations in the transverse plane of occlusion, independent of the sagittal and vertical relationships.
• Types of transversal anomalies are: posterior crossbite (unilateral, bilateral, monodental), scissor bite (unilateral, bilateral, monodental), and cuspid to cuspid.

Etiology: Genetic Factors

• Genetic factors can cause maxillary hypoplasia, mandibular hyperplasia, combinations of both, or syndromes.

Etiology: Habits

• Oral breathing: Caused by nasal obstruction, often persists after the obstruction has been resolved. Causes include allergic rhinitis and adenoid hypertrophy. Consequences include reduced maxillary development, and predominance of lip over paranasal muscles, leading to reduced nasal spine and incisor protrusion.
• Infantile swallowing: Characterized by the tongue's position behind the incisors, and contact with the palate; teeth in contact/close, and a retrusive mandible. Etiologic factors include enlargement of tonsils and oral breathing; characteristics include tongue interposition (between teeth for mandibular stability), and lack of tongue pressure / pressure of buccinator muscles. Consequences include maxillary compression and open bite tendencies.
• Thumb sucking: Effects depend on the position, time, and morphogenetic pattern of thumb sucking. Causes include pressure of the tongue and buccinator muscles, and reduced intraoral air pressure during suction. Consequences include dentoalveolar compression.

Diagnosis

• Diagnosis includes patient history and examination, extraoral and intraoral photos, study models, panoramic radiographs, lateral cephalometric radiographs, frontal cephalometric radiographs, and complementary explorations (basecranial radiography, 99Tc scintigraphy, SPECT, and computed axial tomography).

Treatment

• Early treatment is essential to prevent further dentoalveolar and/or skeletal compensations. This reduces the risk of relapse, increases arch lengths and reduces eruption and tooth retention.
• Therapeutic objectives include controlling habits (oral breathing, thumb sucking, infantile swallowing), maxillary expansion, and the elimination of prematurities.
• Treatment methods depend on the severity of the problem, the age of the patient (deciduous dentition, mixed dentition, or permanent dentition), and the specific type of malocclusion (dentoalveolar, skeletal, true asymmetries).
• Treatment options include removable appliances (acrylic base, Adam clasps, vestibular arch, bite plane, expansion screw) and fixed appliances (palatal arch, quad helix).
• Retention periods after treatment vary depending on patient age and the nature of the correction.

Frontal XR

• Frontal radiographs are important for diagnosing the origin of the anomaly (maxilla, mandible, or a combination) and identifying skeletal or dentoalveolar malocclusions.

Types of Transverse Malocclusions - Clinical Presentation

• Different types of transverse malocclusions, categorized by whether or not they involve mandibular deviation, and the type of skeletal/dentoalveolar involvement will determine the treatment approaches.

Treatment: Skeletal Malocclusions

• Treatment may involve orthopedic approaches (surgery), or orthodontic treatment that is limited in nature, given that the mandibular symphysis typically closes during the first year of life.

Treatment: Dentoalveolar Malocclusions

• Treatment methods often rely on tooth movement utilizing appropriate orthodontic appliances.