Dentosphere : World of Dentistry

 # 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 sol...

 # 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 disp...

 # 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 ...

 # 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 acces...

 # 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 ...

 # 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 i...

 # A key benefit of orthodontic treatment for patients with a pre-existing periodontal compromise (e.g., reduced but healthy periodontium) is: A. Elimination of all PDL forces in the compromised teeth B. Complete regeneration of lost alveolar bone and attachment C. Increased tooth mobility for better functional adaptation D. Optimization of axial loading to distribute occlusal forces more favorably The correct answer is D. Optimization of axial loading to distribute occlusal forces more favorably In patients with pre-existing periodontal compromise (e.g., reduced but stable attachment levels), orthodontic treatment aligns malpositioned teeth—such as flared or tipped incisors—to promote more vertical (axial) force transmission during occlusion, minimizing deleterious lateral or eccentric loads that exacerbate mobility, attachment loss, or alveolar stress in weakened areas. This biomechanical optimization, achieved via controlled intrusion and torque control with light forces (5–15 g...