Kuwait Board Prosthodontics cheat sheet

Prognosis classification (Kwok–Caton): Good = adequate bone support, controlled systemic factors, cooperative patient; Questionable = <25% bone loss but local/systemic factors not fully controlled; Hopeless = >50% bone loss or furcation grade III with non-restorable tooth.

Diagnostic cast mounting: facebow record transfers maxillary arch position relative to hinge axis; interocclusal record at centric relation transfers mandibular position. Mounting accuracy is the foundation for occlusal analysis.

Radiographic crown-to-root ratio: 1:2 ideal, 1:1 minimum acceptable for a single crown; <1:1 indicates compromised support and favors splinting or extraction.

Tooth mobility (Miller): Grade I = <1 mm buccolingual; Grade II = 1–2 mm; Grade III = >2 mm with vertical depression. Grade III typically contraindicates fixed abutment use.

Anticipated restoration longevity depends on: abutment periodontal support, ferrule ≥1.5–2 mm, occlusal scheme, parafunction, and oral hygiene. Document each factor before consent.

Caries risk assessment (CAMBRA-like): low = no active lesions in 12 months; moderate = 1 active lesion; high = ≥2 active lesions or recent restorations. High risk warrants fluoride and dietary intervention before prosthodontic treatment.

Diagnostic wax-up guides both treatment plan and provisional design; it must be approved by the patient before irreversible tooth preparation.

Medical history red flags: uncontrolled diabetes (HbA1c >8%), anticoagulant therapy, head/neck radiation history, bisphosphonate use, and immunosuppression alter sequencing and prognosis.

Ferrule effect: ≥1.5–2 mm of axial dentin height, 360° circumferential, with a continuous 1–2 mm dentin collar; increases fracture resistance of endodontically treated teeth.

Minimum occlusal reduction: 1.5 mm for metal-ceramic (PFM), 1.5–2.0 mm for all-ceramic (lithium disilicate), 0.5–1.0 mm for cast metal. Axial reduction: 1.0–1.5 mm.

Finish line selection: chamfer 1.0–1.2 mm for PFM/all-ceramic; shoulder 1.0–2.0 mm for facial ceramic margin; knife-edge contraindicated for ceramic.

Taper of preparation: 6–10° ideal; >20° compromises retention. Retention increases with surface area, parallel walls, and shorter taper.

Provisional restoration: must maintain occlusal contact, marginal seal, and pulpal protection; bis-acryl or PMMA for >2 weeks; eugenol-containing cements avoided under composite.

Cementation: resin cement for all-ceramic and resin-bonded; glass ionomer for metal/zirconia where moisture control is difficult; zinc phosphate still acceptable for cast metal.

Occlusal adjustment sequence: check in centric relation first, then excursive movements; mark with 40-µm articulating paper; heavy contacts removed on inclines, not on centric stops.

Splinted crowns: use when abutment support is unequal or when replacing a missing tooth with a fixed partial denture; splinting increases load sharing but complicates hygiene and repair.

Complete denture impression: border molding records functional sulcus; final wash with light-body elastomer or zinc oxide-eugenol; selective pressure technique preserves denture-bearing areas.

Neutral zone concept: teeth positioned where forces of tongue, lips, and cheeks balance; critical for severely resorbed mandible.

Posterior palatal seal: 1–1.5 mm depth, located between vibrating line and fovea palatinae; provides retention and reduces gag reflex.

Balanced occlusion for complete dentures: bilateral simultaneous contacts in centric and excursive movements; lingualized occlusion is a common scheme for resorbed ridges.

RPD design: rests seat on prepared rest seats; clasps (circumferential, RPI, RPA) provide retention and reciprocation; major connector should be rigid and cover minimal tissue.

Kennedy classification: Class I bilateral distal extension; Class II unilateral distal extension; Class III bounded posterior edentulous area; Class IV single anterior edentulous area crossing midline.

Applegate's rules modify Kennedy for missing teeth and additional edentulous areas; always note modification spaces separately.

Denture stomatitis: Candida albicans is the primary organism; treat with nystatin or miconazole, denture hygiene, and nocturnal removal; check for ill-fitting prosthesis and xerostomia.

Implant survival vs. success: survival = implant still present; success (Albrektsson criteria) = no mobility, <0.2 mm annual bone loss after first year, no pain, no peri-implant radiolucency.

Loading protocols: immediate loading requires ≥35 Ncm insertion torque and good primary stability; early loading 2–6 weeks; conventional loading 3–6 months.

Bone density (Lekholm–Zarb): Class 1 dense cortical; Class 4 low-density trabecular. Class 4 requires underpreparation or wider implant.

Screw-retained vs. cement-retained: screw-retained allows retrievability and avoids residual cement; cement-retained offers easier esthetics and passive fit in some situations.

Platform switching: abutment narrower than implant platform; reduces crestal bone loss by shifting inflammatory infiltrate away from bone.

Peri-implant mucositis: reversible inflammation of soft tissue; peri-implantitis: inflammation with progressive bone loss. Risk factors include smoking, uncontrolled diabetes, and history of periodontitis.

Implant occlusion: light centric contacts (≈20–30 µm marking), no working/non-working interferences, narrower occlusal table, and flat cusps to reduce off-axial loads.

Minimum interocclusal space: ~7 mm for screw-retained crown with multi-unit abutment; verify with diagnostic wax-up and CBCT before surgery.

Centric relation: maxillomandibular relationship in which condyles articulate with the thinnest avascular portion of their discs, with the complex in the anterior-superior position against the articular eminences; it is a bone-to-bone relationship independent of tooth contact.

Maximum intercuspation (MIP) vs. centric occlusion (CO): MIP is tooth-determined; CO is condyle-determined. Discrepancy >2 mm may require occlusal therapy.

RDC/TMD Axis I: Group I muscle disorders; Group II disc displacements; Group III arthralgia, arthritis, arthrosis. Axis II assesses pain-related disability and psychological status.

TMD first-line therapy: patient education, self-care, NSAIDs, muscle relaxants, occlusal splint (stabilization type, flat plane), and physical therapy. Irreversible treatments (occlusal adjustment, surgery) are not first-line.

Stabilization splint: full-arch coverage, flat occlusal plane, canine guidance or group function, adjusted in centric relation; worn at night.

Bruxism: sleep bruxism is centrally mediated; awake bruxism is stress-related. Management includes splint, CBT, and botulinum toxin in refractory cases.

Occlusal interferences: working-side (BULL rule - buccal upper, lingual lower) and non-working-side (balancing) contacts; non-working interferences are more damaging to the TMJ and periodontium.

Disc displacement with reduction: reciprocal click; without reduction: limited opening with deviation to the affected side and no click.

Zirconia: transformation toughening; 3Y-TZP most common; flexural strength 900–1,200 MPa; opaque, requires veneering for esthetics; avoid hydrofluoric acid etching (use airborne-particle abrasion + MDP primer).

Lithium disilicate: flexural strength ~360–450 MPa; etchable with 5% HF for 20 s; bondable; suitable for single crowns and 3-unit anterior FPDs.

Feldspathic porcelain: highest esthetics, lowest strength (~100 MPa); used for veneers; etch with 9.5% HF.

Resin composite: flexural strength 80–120 MPa; wear resistance lower than ceramic; used for provisionals and some definitive restorations.

PMMA: provisional material; low wear resistance; residual monomer can irritate pulp; bis-acryl has better dimensional stability and less exotherm.

Dental amalgam: high compressive strength, poor esthetics, no adhesive bonding; contraindicated in patients with mercury allergy and in esthetically critical areas.

Glass ionomer: fluoride release, chemical adhesion to tooth, low strength; used for luting and pediatric restorations; resin-modified GI improves strength.

Color science: shade selection under daylight (5,500 K), neutral background; Vita Classical and Vita 3D-Master systems; metamerism causes shade mismatch under different lighting.

Intraoral scanner accuracy: trueness (closeness to actual) and precision (reproducibility); full-arch scans accumulate error; use of reference markers reduces distortion.

CAD/CAM workflow: scan → design (CAD) → manufacture (milling or 3D printing) → post-processing (sintering, polishing, glazing).

Milling: subtractive; zirconia requires sintering shrinkage compensation (~20–25%); titanium and Co-Cr milled with coolant.

3D printing (additive): stereolithography (SLA) for models and provisionals; digital light processing (DLP); selective laser melting (SLM) for metal frameworks.

Digital impression advantages: no impression material, reduced gag reflex, immediate digital storage, easier communication with lab; limitations include subgingival margins and bleeding.

CBCT for implant planning: measure bone width/height, identify inferior alveolar nerve and maxillary sinus; use surgical guide fabricated from CBCT + scan data.

Digital shade matching and face scanning improve esthetic predictability; always verify digitally planned occlusion with an analog or printed verification jig.

STL (stereolithography) and PLY are common export formats; ensure scanner software exports in open format for lab interoperability.

Xerostomia: common in elderly; causes caries, denture intolerance; management includes saliva substitutes, sugar-free gum, fluoride, and frequent water sips.

Polypharmacy: >5 medications increases risk of dry mouth and drug interactions; review medication list before prescribing.

Bisphosphonate-related osteonecrosis of the jaw (BRONJ): risk with IV bisphosphonates and denosumab; avoid elective extractions; conservative management preferred.

Diabetes: HbA1c >8% increases infection and delayed healing; schedule elective surgery when controlled; monitor for hypoglycemia during long appointments.

Anticoagulants: do not routinely stop for minor procedures; check INR for warfarin (target <3.5 for dental surgery); direct oral anticoagulants may require timing adjustment per physician.

Cognitive impairment: simplify treatment, use shorter appointments, involve caregivers; consider removable prostheses over complex fixed work.

Root caries in elderly: fluoride varnish, chlorhexidine, and glass ionomer restorations; recall every 3–6 months.

Parkinson's disease: tremor affects denture retention and oral hygiene; implant-retained overdentures may improve stability.

Informed consent: must include diagnosis, treatment options (including no treatment), risks, benefits, and costs; documented in writing and signed.

Confidentiality: patient records protected; disclosure only with consent or legal requirement; HIPAA-equivalent local regulations apply.

Infection control standard precautions: hand hygiene, gloves, masks, eye protection, and gowns for all patients regardless of diagnosis.

Sterilization: autoclave 121°C at 15 psi for 15–20 min (gravity) or 132°C for 4 min (flash); monitor with biological indicators (Geobacillus stearothermophilus) weekly.

Surface disinfection: intermediate-level disinfectant (e.g., chlorine-based) for clinical contact surfaces; barriers preferred where possible.

Sharp injury protocol: wash with soap and water, report immediately, assess source patient, and initiate post-exposure prophylaxis per protocol.

Professional boundaries: avoid treating family members for complex care where objectivity may be compromised; refer when outside competence.

Record keeping: contemporaneous, legible, signed, and retained per local statute; include radiographs, models, and consent forms.

Evidence hierarchy: systematic reviews/meta-analyses > RCTs > cohort studies > case-control > case series > expert opinion.

PICO framework: Population, Intervention, Comparison, Outcome - used to formulate a focused clinical question.

Sensitivity = true positives / (true positives + false negatives); specificity = true negatives / (true negatives + false positives).

Positive predictive value depends on prevalence; a highly sensitive test is useful for ruling out disease (SnNout); a highly specific test rules it in (SpPin).

Number needed to treat (NNT) = 1 / absolute risk reduction; lower NNT indicates greater clinical benefit.

Randomization reduces selection bias; blinding reduces detection and performance bias; intention-to-treat analysis preserves randomization benefits.

Confidence interval: 95% CI indicates range in which the true effect lies with 95% probability; if it includes 1 for risk ratios or 0 for mean differences, the result is not statistically significant.

Publication bias: positive studies more likely published; funnel plots and Egger's test assess it in meta-analyses.