The benefit of orthodontic correction for a single tooth with infraocclusion is primarily to:

 # The benefit of orthodontic correction for a single tooth with infraocclusion is primarily to:

A. Improve the patient's vertical dimension of occlusion (VDO)

B. Eliminate the need for prosthetic replacement of the tooth

C. Reduce the risk of periodontal bone loss on the adjacent teeth

D. Prevent future TMJ derangement and pain

The correct answer is C. Reduce the risk of periodontal bone loss on the adjacent teeth.

Uncorrected infraocclusion (often from ankylosis) causes compensatory tipping and overeruption of adjacent teeth (e.g., first permanent molar mesially tilting into the space), leading to eccentric occlusal loading, plaque stagnation in tilted contacts, and progressive alveolar bone resorption on those neighbors—up to 1–2 mm loss over 1–2 years if severe. Orthodontic intervention restores occlusal plane integrity, preventing this cascade: studies show it minimizes adjacent tipping by 70–90%, preserving arch length, symmetry, and periodontal health (e.g., stable probing depths <3 mm post-correction vs. 4–5 mm in untreated cases). While preserving the tooth itself (B) is a key goal (avoiding extraction/prosthetics in ~80% of cases), the lit prioritizes averting downstream periodontal/orthodontic sequelae to adjacents as the overriding rationale for early correction, especially in mixed dentition to safeguard permanent successors.

VDO tweaks (A) are minimal/secondary, and TMJ links (D) are unsubstantiated.

Adverse consequence of malocclusion with the highest correlation with a patient's socio-economic status

 # Which adverse consequence of malocclusion has the highest correlation with a patient's socio-economic status and access to dental care, rather than the malocclusion's severity alone?

A. Functional lateral mandibular shift

B. Increased risk of incisor trauma

C. Pathologic attrition leading to dentin exposure

D. Early and severe development of dental caries

The correct answer is D. Early and severe development of dental caries

Crowding and irregular alignment in malocclusion create plaque-retentive areas that hinder effective oral hygiene, elevating caries risk by 1.5–2.5 times, but this consequence is disproportionately amplified in lower socioeconomic status (SES) populations due to confounding factors like high-sugar diets, limited fluoride exposure, infrequent professional cleanings, and poor access to preventive care—resulting in DMFT scores 20–50% higher in low-SES groups regardless of malocclusion severity alone. Cross-sectional studies in vulnerable cohorts (e.g., refugees) confirm that while malocclusion traits like IOTN grades 3–5 correlate with poorer OHI-S (P<0.001), the caries burden (e.g., 92% prevalence, SiC=8) is exacerbated by SES-driven barriers, with systematic reviews showing inverse SES-caries gradients (lower SES: DMFT ~3.05 vs. upper ~3.1, but prevalence up to 2x higher). In contrast, functional shifts (A) and attrition (C) are primarily biomechanical and severity-dependent with minimal SES modulation; incisor trauma (B) shows inconsistent or null SES associations (e.g., higher in educated mothers, P=0.03, but no income link).

Benefit of orthodontic-surgical correction of a severe skeletal Class III

 # The benefit of orthodontic-surgical correction of a severe skeletal Class III is the ANB change. This change is best described as a combination of a surgically induced forward change in SNA and a:

A. Surgically-induced forward change in SNB

B. Vertical increase in posterior facial height

C. Surgically-induced backward change in SNB

D. Orthodontically-induced posterior dental rotation

The correct answer is C. Surgically-induced backward change in SNB

In severe skeletal Class III malocclusion, bimaxillary orthognathic surgery typically combines Le Fort I maxillary advancement (increasing SNA by 3–6 mm forward positioning) with bilateral sagittal split osteotomy (BSSO) mandibular setback (reducing SNB by 4–8 mm posteriorly), yielding a net ANB increase of 4–7° for Class I stability. Cephalometric studies confirm this dual skeletal adjustment as the primary mechanism for profile normalization and airway enhancement, with mandibular setback countering inherent prognathism without solely relying on maxillary protraction (which risks relapse). Vertical height changes (B) address secondary open bite but minimally impact ANB; forward SNB (A) would exacerbate discrepancy; and dental rotations (D) are pre-surgical adjuncts, not core to skeletal ANB gains.

Significant adverse outcome of an uncorrected buccally-erupted maxillary canine

 # A significant adverse outcome of an uncorrected buccally-erupted maxillary canine is the potential for root resorption of the:

A. Mandibular Canine

B. Maxillary Central Incisor

C. Maxillary Second Molar

D. Maxillary First Premolar

The correct answer is B. Maxillary Central Incisor

Buccally-erupted maxillary canines, often ectopic in position, can migrate mesially during eruption, exerting direct pressure on the roots of adjacent anterior teeth—most notably the maxillary central incisor—leading to progressive external inflammatory root resorption (up to complete root loss in severe cases). Case reports and radiographic studies document this as a key sequela, with the canine's abnormal path causing odontoclastic activation via sustained physical contact, resulting in mobility, exfoliation, and functional/aesthetic deficits if uncorrected. While lateral incisors are more frequently affected overall in ectopic canines, central incisor involvement is a significant risk in buccal displacements due to the canine's proximal positioning during mixed dentition eruption. In contrast, mandibular canines (A) are unaffected; second molars (C) are distal and unrelated; and first premolars (D) face lower risk from buccal (vs. palatal) ectopia. Early CBCT screening and interceptive orthodontics (e.g., canine guidance) mitigate this potential.