Orthodontics: Examination and Diagnosis

Course Learning Outcomes (CLOs)

• CLO1: Define orthodontic patient examination and diagnosis related to malocclusions (etiologies). Differentiate skeletal and dental malocclusions, and distinguish between minor tooth movement and major malocclusions.
• CLO2: Assess orthodontic records (models, cephalometric X-rays, facial photographs) to create a problem list.
• CLO3: Discuss different tooth movement types and biological theories. Describe growth modification principles and orthodontic force effects on the maxilla and mandible.
• CLO4: Determine treatment options based on analysis, select the best option considering patient factors, and establish a final treatment plan.

Outline

• Definition
• Main aims
• Normal dental development
• Eruption and exfoliation abnormalities
• Mixed dentition problems
• Planned extraction of deciduous teeth
• Other dental and skeletal problems

Definition

• Interceptive orthodontic treatment: any procedure reducing a developing malocclusion, potentially simplifying or eliminating future treatment.
• Main aims: minimizing malocclusion progression, maintaining midline, minimizing crowding, preventing Class II molar relationships, preventing trauma, and considering psychosocial factors.

Normal Dental Development

• Mixed dentition phase spans from age five or six, to the exfoliation of the last primary tooth.
• Typically, first molars erupt into a half unit II molar relationship guided by the distal surfaces of the second primary molars (flush terminal plane).
• Transition to a Class I molar relationship happens due to early mesial drifting of the lower six into primate space and late mesial drift into the leeway space, plus differential mandibular growth.
• Leeway space: maxilla (1.5mm per side), mandible (2-2.5mm per side).
• Upper permanent incisors erupt into a wider and more proclined arc than the primary incisors (Incisor Liability).
• Upper canines develop palatally, then migrate buccally to be distal to the lateral incisor root apices.

Routine Screening

• General dentists screen children eight to ten years old for developing dental abnormalities.
• Clinical examination detects unusual traits.
• Radiographs (panoramic X-rays) are used when needed.
• Use the ALARP principle for radiography (as low as reasonably practicable).
• Palpate the buccal sulcus to detect permanent maxillary canine eruption abnormalities (around age nine to eleven).

Natal Teeth

• Natal teeth erupt within the first few weeks after birth, usually anterior mandibular primary incisors.
• Natal teeth can be mobile, but usually become firmer relatively quickly.
• Management: If asymptomatic, leave in situ. Remove if interfering with breastfeeding or if mobility poses inhalation risk.

Eruption Cysts

• Fluid or blood accumulation in the follicular space over an erupting tooth's crown.
• Management: Frequently rupture spontaneously but marsupialization sometimes needed.

Failure/Delayed Eruption

• Wide individual variations in eruption time.
• Observe for a period, if disruption or asymmetry noted investigate: radiographic examination.

Causes of Delayed Eruption

• Local factors (mechanical obstruction)
• Congenital absence; crowding; trauma
• Ectopic tooth germs; supernumerary teeth; retained primary teeth; premature primary tooth extraction; dilaceration.
• Systemic conditions: Downs syndrome, cleidocranial dysplasia Turner syndrome, hereditary gingival fibromatosis, cleft lip/palate, rickets.

Unerupted Maxillary Incisors

• Maxillary central incisor is the third most impacted tooth (after third molars and maxillary canines).
• Diagnostic criteria: discrepancy of greater than six months between contralateral maxillary incisor eruption, or lateral incisor prior to central incisor eruption merits radiographic investigation.
• Etiology: barrel-shaped/tuberculate supernumerary tooth, trauma to primary dentition.

Treatment of Unerupted Maxillary Incisors

• Remove physical obstructions.
• Surgical exposure with or without orthodontic traction.
• Open exposure (simple elliptical incision, mucoperiosteal flap with attachment).
• Closed eruption technique.
• Apically positioned flap.
• Incisor removal.
• Autotransplantation.

Unerupted Permanent Maxillary Canines

• Deviation from normal eruption path (palatal in ~85%): impacted.
• Aetiology: long eruption path, reliance on lateral incisor root guidance (diminished or absent), retained primary canines, delayed eruption in maxillary arch relative to premolars.
• Diagnosis: family history, intraoral examination (palpation from 8-10 years), radiographic examination if palpation negative.
• Management mostly surgical exposure followed by orthodontic alignment, autotransplantation, extraction, or leaving in situ.

Enforced vs Elective Extractions

• Enforced extraction: necessary due to poor prognosis.
• Elective extraction: optional, part of a treatment plan.
• Balancing extraction: opposite side of same arch.
• Compensating extraction: opposing quadrant to maintain buccal occlusion, allow forward molar drift.

Early Loss of Primary Teeth

• Reasons: extraction due to caries or trauma.
• Consequences: implications on developing occlusion, space distribution and symmetry, affecting successor eruption timing

Early Loss of Primary Canines

• Consequences: midline shift (unilateral loss), leading to unbalanced dentition (often in crowded dentition), balancing extraction potentially needed to maintain midline.

Early Loss of Primary First Molars

• Consequences: unilateral early loss can lead to midline shift (especially in crowded dentition).
• Early loss often creates space loss by forwards movement of the buccal segments, potentially increasing premolar crowding.
• Balancing extraction in some cases, but primarily monitored, as most cases won't automatically require additional extraction.

Early Loss of Primary Second Molars

• Least effect on midline, but affects position of first permanent molar potentially causing tipping, rotation and space loss through buccal movement.
• Early extraction allows movement of adjacent teeth forward, consideration of a space maintainer may be required.
• Rarely needs balancing/compensatory extractions unless restoration or general anesthetic is needed.

Impacted First Permanent Molars

• Common in maxillary arch.
• Impaction against second deciduous molars suggests crowding.
• Some cases resolve spontaneously but rare after 8 years.
• Management: Mild cases might respond (2mm overlap between second deciduous and permanent molars) to tightening separating wire over two months, or moderate-severe requires appliance for molar distalization.
• Other options: observation, extraction for abscess or caries concerns, addressing potential space loss later with restorative measures.

Prolonged Retention of Primary Teeth

• Presence of permanent successor, retained primary (causing deflection of permanent tooth) needs extraction, particularly if causing deflection.
• Possible for permanent successor to not resorb overlying primary root. Encourage self-exfoliation, or extraction under local anesthesia.

Ankylosis and Infraocclusion

• Infraocclusion: tooth fails to achieve or maintain proper relationship.
• Primary infraocclusions often erupt into occlusion, but later seem submerged.
• Reasons: genetic, permanent successor resorption failure, agenesis of permanent successor, trauma, infection.
• Management (permanent successor present): observation, restoration, or extraction based on space and position, or other teeth position. If no successor, extraction is often the long-term management strategy.

Ankylosed Permanent Teeth

• Ankylosis most frequent in maxillary central incisors, often due to trauma (intrusion, avulsion).
• Replacement resorption, ankylosis, infraocclusion possible consequences.
• Management varies based on factors like space availability and position of the unerupted/permanent tooth. Potential for space closure, restorative replacement, or extraction.

Hypodontia

• Developmental absence of one or more teeth (excluding third molars).
• Hypodontia: 1-6 absent teeth.
• Oligodontia: >6 missing teeth.
• Anodontia: complete tooth absence in one or both dentitions.
• Consequences: Centerline shift, spacing, malposition, retained deciduous teeth.

Supernumerary Teeth

• Additional teeth beyond the normal series.
• Genetic component, more common in males.
• Occur uniquely or in groups, frequently in maxillary anterior region, but also in premolar/molar areas.
• Consequences include eruption failure, displacement, crowding.
• Management: removal for eruption issues or displacement, or if causing crowding, or cystic formation; otherwise, monitoring usually sufficient.

Primary Failure of Eruption (PFE)

• Rare, isolated condition.
• Localized disruption to molar eruption.
• Possible cause: autosomal dominant mutations in PTH1R (also associated with osteoarthritis).
• Management: difficult. Extraction usually followed by space closure/prosthetic replacement, sometimes segmental bony osteotomy and orthodontic extrusion, or localized coronal buildup.

Transposition

• Complete positional switching of adjacent teeth.
• Causes include positional interchange of developing tooth/buds, alteration of eruption paths, retention of primary teeth, or trauma.
• Decision to correct order of transposition or accept it, or extract an affected tooth.

Dilaceration

• Distortion/bend in a tooth root.
• Aetiology: developmental (crown turned upward, labially, without enamel/dentine disturbance)—or trauma from incisor intrusion, causing underlying permanent crown being deflected palatally.
• Mild cases might be treated by exposure and traction; severe cases often need extraction and space maintenance.

Median Diastema

• Normal spacing between maxillary central incisors in developing dentition ("ugly duckling" stage, aged 8-9 years).
• Usually closes as laterals and canines erupt.
• Causes: physiological (normal development); familial/racial; small teeth in large jaws (spaced dentition); missing teeth; midline supernumerary tooth.
• Proclination, prominent fraenum also contribute.

Oral Habits

• Thumb/digit sucking, mouth breathing, tongue thrusting, lip sucking, etc.
• Frequency and intensity influence malocclusion severity.
• Prolonged habits affect tooth eruption in various ways (anterior open bite, incisor proclination, narrow maxillary arch, posterior crossbite, increased lower face height).
• Management: initial non-invasive methods (psychological, habit reversal), otherwise simple fixed appliances using palatal arches. Intervention early lessens later correction complexity (especially for malocclusion).