Fellowship of the Royal Australasian College of Dental Surgeons (FRACDS) Final Examination

Correct: Guided tissue regeneration (GTR) is the evidence-based standard for treating vertical (infrabony) defects, as it utilizes a barrier membrane to prevent epithelial downgrowth, allowing for the regeneration of bone, cementum, and periodontal ligament.

Correct: In both internal auditing and professional surgical practice, the management of conflicts of interest centers on transparency and disclosure. A standardized informed consent protocol ensures that patients are informed of potential biases, which is a key control for ethical risk management and maintaining the integrity of the surgeon-patient relationship.

Correct: The PASS principles (Primary closure, Angiogenesis, Space maintenance, and Stability) are fundamental to Guided Bone Regeneration (GBR). In non-contained defects, such as vertical augmentations, the graft is subject to external pressure from the soft tissue flap. Without mechanical support like tenting screws or titanium-reinforced membranes, the space is lost, the graft is compressed or displaced, and fibrous tissue ingrowth occurs instead of osteogenesis.

Correct: Leukocyte-Platelet Rich Fibrin (L-PRF) is produced through a simplified centrifugation process without the addition of anticoagulants or bovine thrombin. This results in a natural fibrin matrix that traps platelets and leukocytes, allowing for a slow, sustained release of essential growth factors such as VEGF, TGF-beta, and PDGF over 7 to 14 days. This sustained release is clinically superior for tissue remodeling and angiogenesis compared to the rapid release seen in traditional PRP.

Incorrect: Adding bovine thrombin is a technique used in PRP to initiate clotting but is not used in PRF, which relies on natural polymerization; furthermore, bovine thrombin carries risks of developing antibodies against Factor V. Single-spin protocols generally fail to achieve the necessary platelet concentration required for therapeutic PRP, and excluding leukocytes is not always desirable as they contribute to the immune response and growth factor pool. PRP in its liquid form lacks the structural integrity of a fibrin clot and cannot provide mechanical support for a bone graft or membrane.

Takeaway: L-PRF provides a bioactive, additive-free fibrin scaffold that facilitates prolonged growth factor release and cellular migration, making it highly effective for bone and soft tissue augmentation in oral surgery.

Correct: The greater palatine artery (GPA) typically runs in a groove at the junction of the alveolar and palatal processes. The distance from the GPA to the cementoenamel junction (CEJ) of the maxillary teeth varies significantly with the shape of the palate. In patients with a shallow palatal vault, the artery is much closer to the CEJ (approximately 7 mm), whereas in a high vault, it may be 17 mm away. Recognizing this variation is essential for risk assessment to prevent intraoperative hemorrhage and ensure patient safety during soft tissue harvesting.

Incorrect: The incisive foramen is an anterior landmark for the nasopalatine nerve and is not the primary concern for the greater palatine artery in the posterior palate. While mucosal thickness is relevant for graft quality, it does not dictate the safe distance from the neurovascular bundle. Palatal exostoses may complicate the surgical site, but they are not the primary anatomical guide for avoiding the GPA; in fact, they often make the tissue thinner and more difficult to harvest safely.

Takeaway: Anatomical variation in palatal vault height is the most critical factor in determining the safe zone for harvesting connective tissue grafts to avoid the greater palatine artery.

Correct: The biological principle of Guided Tissue Regeneration (GTR) relies on the exclusion of faster-migrating epithelial and gingival connective tissue cells to allow slower-migrating cells from the periodontal ligament and alveolar bone to repopulate the root surface. Space maintenance is a critical requirement; if the membrane collapses into the defect, there is no room for the blood clot to stabilize or for the progenitor cells to migrate and differentiate into new cementum, periodontal ligament, and bone.

Incorrect: Intentional membrane exposure is contraindicated in GTR as it leads to bacterial colonization, infection, and premature degradation of the barrier, which halts the regenerative process. Promoting epithelial migration is the opposite of the goal of GTR, as epithelial cells form a long junctional epithelium that prevents true periodontal regeneration. High macro-porosity would allow gingival fibroblasts to penetrate the barrier, leading to fibrous repair rather than the desired regeneration of bone and periodontal attachment.

Takeaway: Successful Guided Tissue Regeneration requires the strict exclusion of epithelial cells and the maintenance of a stable, protected space for the recruitment of osteogenic and periodontal progenitor cells.

Correct: In the severely atrophic mandible, the blood supply shifts from a centripetal (endosteal) to a centrifugal (periosteal) pattern. Fractures through implant sites occur in bone with already limited volume and compromised vascularity. Load-bearing fixation, typically a 2.4mm or 2.7mm locking reconstruction plate, is mandatory because the atrophic bone lacks the cross-sectional area to contribute to load-sharing. Primary bone grafting is often indicated to provide osteoconductive and osteoinductive elements to a site with poor healing potential.

Incorrect: Load-sharing mini-plates are insufficient for atrophic mandibles because the bone cannot support the functional loads, leading to hardware failure or non-union. While infection is a risk, the primary biomechanical failure in atrophic fractures is non-union, not osteomyelitis, and explantation without rigid fixation is contraindicated. Load-sharing fixation along the superior border is inappropriate for atrophic bone where the height is insufficient to support such hardware. Rigid intermaxillary fixation is poorly tolerated in the elderly and does not provide the necessary internal stability for a displaced fracture in an atrophic mandible.

Takeaway: Surgical management of fractures in the atrophic mandible requires load-bearing fixation to compensate for the lack of bone volume and the shift to periosteal-dependent vascularity.

Correct: Conventional loading is predicated on the biological process of osseointegration, where initial mechanical (primary) stability is gradually replaced by biological (secondary) stability. This transition involves a period where total stability may actually decrease (the stability dip) as the old bone is resorbed and new bone is formed via appositional growth. A robust control system must ensure that functional loading occurs only after this biological transition is sufficiently complete, typically after a healing period of 3 to 6 months depending on bone quality and location.

Incorrect: Option b describes a threshold often used for immediate loading, which is a different protocol than the conventional loading discussed. Option c is incorrect because a standardized timeframe ignores the clinical reality that different bone types (e.g., Type IV in the maxilla) and the presence of grafts may require longer healing periods than a fixed 12-week rule. Option d describes immediate non-functional loading, which is a distinct surgical management strategy and does not align with the conventional loading protocol of leaving the implant undisturbed during the healing phase.

Takeaway: The success of conventional loading depends on the biological transition from primary mechanical stability to secondary biological stability through an undisturbed healing period.

Correct: In the posterior maxilla, when the residual bone height is less than 4-5 mm, a lateral window sinus floor elevation (Caldwell-Luc approach) is the gold standard. This technique allows for direct visualization and the placement of a significant volume of bone graft material. A delayed approach (allowing 6-9 months for graft maturation) is typically required in cases with such minimal residual bone to ensure that the implant achieves adequate primary stability and long-term osseointegration in the newly formed bone.

Incorrect: The crestal approach (osteotome or hydraulic) is generally reserved for cases where there is at least 5-6 mm of residual bone height to provide initial stability for the implant. Short implants (6 mm) are contraindicated when there is only 3 mm of bone because they would lack primary stability and have a high risk of failure or displacement into the sinus. The alveolar ridge split technique is primarily used to increase the horizontal width of the ridge, not the vertical height or to address sinus pneumatization.

Takeaway: For posterior maxillary sites with less than 5 mm of residual bone height, a lateral window sinus augmentation with delayed implant placement is the most predictable surgical strategy for prosthetic success.

Correct: In cases of implant fracture due to excessive mechanical forces, such as those seen in sleep-related psychosis or severe parasomnias, the fractured implant is non-restorable and must be removed. Explantation followed by thorough debridement is necessary to remove any associated inflammatory tissue. A delayed approach to reconstruction (bone grafting) allows for the resolution of any infection and assessment of the patient’s behavioral stability. The use of a high-impact nocturnal orthotic is essential to protect future restorations from the same forces that caused the initial failure.

Incorrect: Immediate replacement of the implant is contraindicated because the site is likely compromised by inflammation and the underlying cause of the fracture (nocturnal trauma) has not yet been managed. Subperiosteal frames are generally not indicated for localized implant failures and carry a high risk of complications in patients with poor behavioral control. Retaining a fractured apical segment is a risk for chronic infection and prevents proper site preparation for future reconstruction.

Takeaway: Surgical management of implant failure in patients with sleep-related psychosis must prioritize the removal of failed hardware and the mitigation of mechanical trauma before attempting re-implantation.