National Board Dental Hygiene Examination (NBDHE)

Correct: The primary purposes of a provisional restoration include pulpal protection and the maintenance of periodontal health. Sensitivity to cold often indicates a compromised marginal seal, while gingival inflammation and bleeding are frequently caused by over-contoured axial surfaces or poor marginal fit that facilitates plaque accumulation. Ensuring proper contours (emergence profile) and marginal adaptation is essential to stabilize the periodontium before proceeding to definitive impressions.

Incorrect: Modifying the occlusal scheme to group function may be a design choice but does not address the biological issues of sensitivity and inflammation. Adjusting esthetics like shade and translucency is a secondary goal that should only be finalized once biological stability is achieved. Increasing the vertical dimension of occlusion is a major treatment planning decision that should not be used as a reactive measure to address localized periodontal or pulpal irritation.

Takeaway: Provisional restorations must serve as a biological template where marginal integrity and physiological contours are prioritized to ensure pulpal protection and periodontal health.

Correct: A comprehensive periodontal evaluation is the essential first step when an abutment tooth exhibits significant attachment loss, such as a 6mm probing depth and furcation involvement. In fixed prosthodontics, the long-term success of a restoration is entirely dependent on the health and stability of the supporting periodontium. Determining the prognosis and restorability of the existing abutments ensures that the treatment plan is biologically sound and meets the patient’s expectations for longevity.

Incorrect: Increasing the span of the bridge by involving teeth #2 and #6 without first addressing the periodontal health of the existing site ignores the underlying pathology and risks the failure of a more complex restoration. Recommending a removable partial denture prematurely fails to respect the patient’s preference for a fixed solution and bypasses the diagnostic phase. Initiating endodontic therapy is inappropriate as the primary issue is periodontal (bone loss and furcation) rather than pulpal, and it does not address the structural or periodontal viability of the tooth as an abutment.

Takeaway: The foundation of any fixed prosthodontic treatment plan must be a thorough diagnostic assessment of the periodontal health and structural integrity of the potential abutment teeth.

Correct: Prosthetically driven treatment planning is the definitive standard for complex implant rehabilitations, particularly in the esthetic zone. By starting with the desired prosthetic outcome (the diagnostic wax-up) and using digital integration (CBCT and surface scans), the clinician ensures that implants are placed in the ideal three-dimensional position to support the planned teeth. This prevents common complications such as poor emergence profiles, unfavorable screw access channels, and excessive cantilever lengths that often arise when surgery is performed without a restorative blueprint.

Incorrect: Surgically driven approaches often lead to implants being placed where bone is available rather than where the tooth should be, necessitating compromised prosthetic designs or angled abutments that can complicate hygiene and biomechanics. Freehand techniques, even with provisionalization, carry a high risk of malpositioning in the esthetic zone where millimeters of deviation can cause failure. Maximizing the number of implants without a prosthetically driven plan does not address the fundamental need for the implants to be located within the restorative envelope and may actually hinder the ability to create a cleansable and esthetic prosthesis.

Takeaway: The integration of a diagnostic wax-up with CBCT-guided surgery represents the most effective methodology for ensuring that implant placement supports both the biomechanical stability and the esthetic requirements of the final prosthesis.

Correct: When preparation geometry is compromised, such as with a total occlusal convergence exceeding 20 degrees and axial wall heights less than 4 mm, the restoration cannot rely on mechanical retention alone. Adhesive resin cements, particularly those utilizing MDP (10-methacryloyloxydecyl dihydrogen phosphate), create a chemical bond with the metal oxides in zirconia. This chemical adhesion, combined with the increased surface area from alumina air-abrasion, is necessary to prevent displacement of the restoration in non-retentive preparations.

Incorrect: Zinc phosphate is a non-adhesive luting agent that relies entirely on mechanical interlocking; it provides no chemical bond and would likely fail on a non-retentive preparation. Resin-modified glass ionomer (RMGI) is a popular choice for zirconia but is generally recommended only when the preparation has adequate resistance and retention form, as its bond strength is significantly lower than that of adhesive resin. Traditional glass ionomer lacks the physical properties and bond strength necessary to compensate for poor preparation geometry and is more sensitive to early moisture contamination.

Takeaway: Adhesive resin cementation with MDP-based chemistry is the treatment of choice for zirconia restorations when the preparation geometry provides inadequate mechanical resistance and retention.

Correct: Polyether is naturally hydrophilic, which allows it to adapt better to tooth structure and capture fine detail in the presence of residual moisture compared to PVS. However, polyether is also known for its high stiffness (modulus of elasticity). In a patient with open embrasures and recession, these areas must be blocked out to prevent the impression from becoming mechanically locked in the mouth or causing trauma to the periodontium upon removal.

Incorrect: The use of latex gloves is contraindicated with PVS because sulfur compounds in the latex inhibit the platinum-catalyzed addition polymerization reaction, leading to a tacky surface. PVS actually has a lower modulus of elasticity (more flexible) than polyether, making polyether the more rigid material. Polyether is dimensionally stable but is also prone to imbibition (absorbing water); storing it in a moist environment for 24 hours would cause significant dimensional inaccuracies and distortion.

Takeaway: Polyether’s hydrophilicity is ideal for subgingival margins, but its high rigidity requires careful blocking of undercuts to ensure safe removal from the oral cavity.

Correct: A full-thickness flap is indicated when the clinician encounters anatomical challenges that cannot be managed blindly. Visualizing the bony topography is essential when a dehiscence or fenestration is suspected, as it allows for the proper placement of the implant within the alveolar housing and the simultaneous application of guided bone regeneration (GBR) if necessary. Flapless surgery, while less invasive, limits the clinician’s ability to assess and treat these defects, potentially leading to implant failure or poor aesthetic outcomes.

Incorrect: A wide zone of keratinized tissue is generally a favorable condition for a flapless approach, as it allows for a tissue punch while maintaining a healthy margin of attached gingiva. A stable surgical guide is a tool that facilitates the accuracy of a flapless procedure rather than a reason to abandon it. While systemic health like controlled diabetes is important for overall healing, it does not serve as a primary clinical indicator for choosing a flap over a flapless technique during the surgical phase.

Takeaway: The primary indication for reflecting a full-thickness flap over a flapless approach is the necessity for direct visualization of the bone to manage anatomical defects or ensure proper implant positioning.

Correct: In healthy TMJ biomechanics, the intermediate zone of the articular disc is the thinnest and most central portion, designed to be the primary articulating surface. During translation, the disc moves posteriorly relative to the condyle due to the passive elastic tension of the superior retrodiscal lamina (stratum superius), while the condyle is pulled forward by the inferior head of the lateral pterygoid. This coordinated movement ensures the intermediate zone remains interposed between the condyle and the articular eminence, which is the hallmark of normal function.

Incorrect: The superior head of the lateral pterygoid muscle is primarily active during mandibular closure and the power stroke to stabilize the disc-condyle complex, rather than actively pulling the disc anteriorly during opening. The posterior band of the disc is thicker and not intended for primary loading; loading this area or the vascularized retrodiscal tissues typically results in pain and internal derangement. The collateral (discal) ligaments attach the disc to the medial and lateral poles of the condyle, not the temporal bone, ensuring the disc translates with the condyle rather than remaining fixed to the skull.

Takeaway: Normal TMJ function depends on the intermediate zone of the disc remaining the load-bearing interface between the condyle and the articular eminence throughout the translational cycle.

Correct: The most effective control for managing changes in Occlusal Vertical Dimension (OVD) is the use of a diagnostic interim prosthesis. This allows the clinician to evaluate the patient’s neuromuscular adaptation, speech (specifically sibilant sounds), and comfort over a functional period (usually 6-8 weeks). If the patient develops muscle fatigue, TMJ discomfort, or persistent phonetic issues during this trial phase, the OVD can be adjusted reversibly before irreversible tooth preparation or the fabrication of expensive definitive restorations.

Incorrect: Relying solely on static measurements like the closest speaking space or rest space is insufficient because these are diagnostic aids that do not account for long-term functional adaptation. Increasing OVD based only on material thickness requirements (e.g., 1.5mm) ignores the biological and physiological limits of the patient’s masticatory system. While Gothic Arch tracings are highly accurate for determining the horizontal centric relation, they do not provide a mechanism to test the patient’s tolerance to a vertical change over time.

Takeaway: A functional trial period with a provisional or interim prosthesis is the essential clinical step to verify patient adaptation to a new occlusal vertical dimension before definitive treatment.

Correct: The Golden Proportion is a mathematical ratio (1.618:1) often cited in esthetic dentistry, but clinical research has shown it is only present in a small percentage of natural smiles. Relying solely on it ignores individual variations such as facial width, lip support, and ethnic characteristics, which are essential for a natural-looking result. A risk assessment of such a treatment plan must identify that rigid adherence to mathematical formulas without considering individual facial harmony can lead to suboptimal esthetic outcomes.

Incorrect: The suggestion that the Golden Proportion leads to structural failure is incorrect because the ratio relates to the perceived width of the teeth from a frontal view, not the actual physical thickness or material strength of the restoration. The claim that it is a universal standard of care is false; it is one of many tools, and many clinicians prefer other methods like the Recurring Esthetic Dental (RED) proportion. The assertion that it only applies to the mandibular arch is factually incorrect, as it is traditionally discussed in the context of the maxillary anterior segment.

Takeaway: Effective esthetic diagnosis requires a holistic facial analysis that accounts for individual patient variability rather than relying strictly on rigid mathematical ratios like the Golden Proportion.