Occlusal feature most frequently associated with the development of abfraction lesions and non-carious cervical lesions

 # Which of the following occlusal features is most frequently associated with the development of abfraction lesions and non-carious cervical lesions?

A. Class II Division 1 with deep overbite

B. Severe Anterior Open Bite

C. Bilateral Posterior Crossbite in CR and CO

D. Non-working side occlusal interferences (mediotrusive contacts)

The correct answer is D. Non-working side occlusal interferences (mediotrusive contacts)

Non-working side occlusal interferences—contacts on the balancing (non-working) side during lateral mandibular excursions (mediotrusive movements)—generate eccentric tensile and compressive stresses that induce cervical tooth flexure, particularly in premolars and molars, promoting microfractures and enamel/dentin loss characteristic of abfraction lesions and NCCLs. Finite element models and clinical studies demonstrate these interferences elevate lesion risk by 2–4 times via sustained shearing forces (up to 50–100 N during excursions), with prevalence up to 70% in affected teeth versus <20% in interference-free occlusions. Elimination via selective grinding often halts progression, confirming causality. In contrast, Class II Division 1 deep overbite (A) primarily causes anterior trauma rather than lateral stress; severe anterior open bite (B) reduces overall occlusal loading; and bilateral posterior crossbite in CR/CO (C) may induce asymmetric forces but lacks the excursive specificity for abfraction predominance.

Benefit of orthodontic treatment in reducing anterior mandibular crowding

 # The benefit of orthodontic treatment in reducing anterior mandibular crowding is often linked to the reduction of Gingival Index scores. This is primarily because proper alignment leads to:

A. A greater volume of keratinized tissue around the incisors

B. A reduction in plaque accumulation and gingival inflammation

C. Increased vascularity and nutrient supply to the PDL

D. Increased resistance to future recession and attachment loss

The correct answer is B. A reduction in plaque accumulation and gingival inflammation

Severe anterior mandibular crowding creates plaque-retentive interproximal and gingival crevices, elevating Gingival Index scores by 1–2 points on average due to chronic low-grade inflammation from bacterial accumulation. Orthodontic alignment (e.g., via archwire sequencing or IPR) enhances self-performed oral hygiene efficacy—reducing plaque index by 25–40% and GI by 0.5–1.0 within 6–12 months, as shown in randomized trials—by facilitating direct bristle/floss access and disrupting biofilm habitats. This direct causal pathway outperforms secondary effects like tissue volume gains (A, minimal post-alignment), PDL vascular changes (C, unrelated to surface inflammation), or recession resistance (D, a downstream periodontal outcome rather than primary GI driver).

Key adverse consequence of uncorrected severe Class III malocclusion during adolescence

 # A key adverse consequence of uncorrected severe Class III malocclusion during adolescence is often an exacerbated negative self-perception primarily due to:

A. The convex profile resulting from the mandibular retrusion

B. Difficulty with mandibular posture and chewing

C. Increased risk of dental trauma to the mandibular incisors

D. The ‘dish face’ concave facial profile with prominent chin (prognathism)

The correct answer is D. The ‘dish face’ concave facial profile with prominent chin (prognathism)

Severe Class III malocclusion in adolescents often manifests as a concave "dish face" profile due to mandibular prognathism or relative maxillary retrusion, creating a prominent chin and retruded midface that deviates markedly from ethnic norms of facial harmony—leading to heightened self-consciousness, bullying, and diminished self-esteem as measured by tools like the Orthognathic Quality of Life Questionnaire (OQLQ), with scores 20–40% lower in untreated cases. Longitudinal psychosocial studies confirm this aesthetic distortion as the primary driver of negative self-perception (effect size d=0.8–1.2), surpassing functional concerns, unlike the convex profile in Class II (A, reversed etiology) or trauma risks more pronounced in protrusive uppers (C).

Malocclusion with highest risk for root resorption of the maxillary incisors

 # Which specific malocclusion, due to its inherent nature, presents the highest mechanical risk for palatal root resorption of the maxillary incisors during orthodontic alignment?

A. Skeletal Class III with severe reverse overjet

B. Deep Bite Class I with severe mandibular crowding

C. Impacting a maxillary canine horizontally near the central incisor root

D. Severe Class II Division 1

The correct answer is D. Severe Class II Division 1

In severe Class II Division 1 malocclusion, the proclined maxillary incisors necessitate substantial labial-to-lingual retraction during alignment (typically 4–7 mm bodily movement), which approximates the incisor roots to the lingual (palatal) cortical plate—reducing the root-to-cortex distance to <1 mm and imposing sustained compressive forces that elevate the risk of orthodontically induced inflammatory root resorption (OIIRR) on the palatal aspect by 1.5–2.5 times compared to Class I or III cases. Cephalometric and CBCT studies confirm this inherent biomechanical vulnerability, with resorption volumes up to 20–30% greater in retracted incisors due to limited PDL buffering against the denser palatal bone, independent of treatment duration or extractions. In contrast, skeletal Class III (A) often involves labial proclination away from the palatal plate; deep bite Class I (B) rarely requires such retraction; and canine impaction (C), while locally risky, lacks inherent malocclusal predisposition and shows no significant association when surgically distanced pre-alignment.