Central Regional Dental Testing Service (CRDTS) Overview
These study notes are designed to help candidates prepare for the Central Regional Dental Testing Service (CRDTS) dental hygiene board exam. The content is anchored to official sources including DANB, ADEX, CDC, and OSHA guidelines. Each subject area covers key concepts, clinical applications, high-yield distinctions, common pitfalls, and review tasks. Candidates should verify specific exam dates, fees, and eligibility with the official CRDTS or ADEX testing agencies.
For Dental Conquer practice planning, this module is tracked as 80 questions over about 120 minutes with a listed pass mark of 70%. Treat those numbers as practice baselines and verify the current official format before scheduling.
How This Guide Is Organized
The sections below turn the syllabus into studyable subject blocks. Read a subject first, explain the must-know ideas without notes, then use questions and flashcards to test whether the knowledge holds under pressure.
- Periodontal Assessment and Clinical Data Collection
- Radiographic Interpretation and Radiation Safety
- Medical History and Patient Risk Management
- Clinical Instrumentation and Deposit Removal
- Pharmacology and Pain Control Modalities
- Professional Ethics and Infection Control
Exam Snapshot and Readiness Target
Format: 80 questions, 120 minutes, pass mark 70% (practice baseline; verify official pass mark with CRDTS)
Candidate level: Entry-to-practice dental hygiene licensure
Readiness target: Competency in periodontal assessment, radiography, medical history, instrumentation, pharmacology, ethics, and infection control
Most candidates should budget at least 38+ focused study hours, then adjust upward for unfamiliar clinical systems, regulatory content, or specialty-level case reasoning.
Periodontal Assessment and Clinical Data Collection
Syllabus Focus
- Periodontal probing and charting
- Clinical attachment level (CAL) measurement
- Bleeding on probing (BOP)
- Furcation involvement and mobility grading
- Gingival index and plaque index
- Periodontal disease classification (AAP 2018)
Key Notes
- Periodontal probing depth (PD) is measured from the gingival margin to the base of the sulcus/pocket; normal ≤3 mm.
- Clinical attachment level (CAL) is measured from the CEJ to the base of the pocket; CAL = PD + recession (if CEJ exposed) or PD - overgrowth.
- Bleeding on probing indicates inflammation; absence of BOP is a strong predictor of periodontal stability.
- Furcation involvement is graded I-III: Grade I = probe enters ≤3 mm horizontally; Grade II = >3 mm but not through; Grade III = through-and-through.
- Mobility is graded 0-3: 0 = physiologic; 1 = <1 mm horizontal; 2 = >1 mm horizontal; 3 = vertical mobility.
- AAP 2018 classification: Periodontitis is staged (I-IV) based on severity and complexity, and graded (A-C) based on progression rate and risk factors.
Must Know
- Correct probing technique: parallel to tooth, walking probe, 20-25g force, six sites per tooth.
- Distinguish between pseudopocket (gingival enlargement) and true pocket (attachment loss).
- Radiographic bone loss patterns: horizontal vs. vertical (angular) defects.
- Risk factors: smoking, diabetes, poor oral hygiene, genetic susceptibility.
Clinical and Exam Application
- Use CAL to determine true attachment loss; PD alone may overestimate in cases of gingival hyperplasia.
- BOP is a key metric for monitoring treatment response; persistent BOP indicates need for re-instrumentation.
- Furcation involvement affects prognosis and treatment planning; Grade II/III may require surgical intervention.
High-Yield Distinctions
- Probing depth vs. CAL: PD is from gingival margin; CAL is from CEJ.
- Gingivitis vs. periodontitis: gingivitis has no attachment loss; periodontitis has CAL.
- Chronic vs. aggressive periodontitis: chronic has slow progression; aggressive has rapid attachment loss and familial pattern (AAP 2018 replaced these with staging/grading).
- Necrotizing periodontal diseases: NUG/NUP present with pain, pseudomembrane, and fetor oris; associated with stress, smoking, immunosuppression.
Common Pitfalls
- Confusing probing depth with attachment level; always note recession or overgrowth.
- Using excessive probing force causing pain and false deep readings.
- Missing furcation involvement due to inadequate probing technique (use Nabers probe).
- Assuming BOP is always pathological; mild BOP may be normal in gingivitis.
Review Tasks
- Practice probing on typodonts or manikins to calibrate force and technique.
- Review AAP 2018 classification case examples.
- Calculate CAL from given PD and recession measurements.
- Identify furcation grades on radiographs and models.
Radiographic Interpretation and Radiation Safety
Syllabus Focus
- Radiation biology and protection (ALARA)
- Intraoral and extraoral imaging techniques
- Normal radiographic anatomy
- Caries detection and classification
- Periodontal bone loss assessment
- Quality assurance and infection control in radiography
Key Notes
- ALARA principle: minimize patient and operator exposure through proper technique, shielding, and fast film/sensors.
- Lead apron with thyroid collar is required for all intraoral radiographs; use of rectangular collimation reduces dose.
- Bisecting angle technique: vertical angulation is perpendicular to the bisector of the angle between tooth and film; errors cause elongation or foreshortening.
- Paralleling technique: film parallel to tooth, central ray perpendicular; preferred for accuracy.
- Normal anatomy: lamina dura (continuous white line around root), periodontal ligament space (thin radiolucent line), trabecular bone pattern.
- Caries: radiolucent lesions; interproximal caries seen on bitewings; occlusal caries may appear as radiolucent triangles under enamel.
Must Know
- Radiation effects: stochastic (cancer, genetic) vs. deterministic (erythema, cataracts); no threshold for stochastic.
- Patient shielding: lead apron with thyroid collar for all intraoral exposures; no need for digital sensors to be covered.
- Film/sensor placement errors: cone-cut, overlapping, apical cutoff, elongation/foreshortening.
- Quality assurance: stepwedge test, film processing checks, retake analysis.
Clinical and Exam Application
- Use bitewings for interproximal caries detection and crestal bone level assessment.
- Periapical radiographs for periapical pathology, root morphology, and endodontic evaluation.
- Panoramic radiographs for impacted teeth, jaw pathology, and TMJ assessment (limited detail).
High-Yield Distinctions
- Radiolucent vs. radiopaque: radiolucent (dark) = caries, pulp, PDL space, sinus; radiopaque (white) = enamel, dentin, bone, restorations.
- Caries depth: E1 (enamel outer half), E2 (inner half), D1 (dentin outer third), D2 (middle third), D3 (inner third).
- Periodontal bone loss: horizontal (even reduction) vs. vertical (angular defect).
- Film vs. digital: digital has lower dose, faster processing, but requires infection control of sensors.
Common Pitfalls
- Misinterpreting cervical burnout (radiolucent area at CEJ) as caries.
- Overlapping contacts due to incorrect horizontal angulation.
- Forgetting to use thyroid collar on pediatric patients.
- Assuming panoramic radiographs show fine detail; they are for screening, not diagnosis of caries.
Review Tasks
- Practice identifying anatomical landmarks on periapical and panoramic radiographs.
- Review ALARA principles and radiation safety protocols from DANB RHS outline.
- Calculate exposure times for different film speeds.
- Identify and correct common technique errors.
Medical History and Patient Risk Management
Syllabus Focus
- Medical history review and updates
- Vital signs measurement and interpretation
- Common medical conditions and dental implications
- Medication considerations (anticoagulants, bisphosphonates, etc.)
- Emergency preparedness and management
- Informed consent and documentation
Key Notes
- Medical history must be reviewed and updated at each appointment; document changes and patient responses.
- Vital signs: blood pressure, pulse, respiration; normal BP <120/80; hypertension stages guide treatment modifications.
- Anticoagulants (warfarin, DOACs): consult physician for INR if needed; avoid NSAIDs; local hemostatic agents may be used.
- Bisphosphonates: risk of medication-related osteonecrosis of the jaw (MRONJ); avoid invasive surgery if possible.
- Emergency kit: oxygen, epinephrine, antihistamine, nitroglycerin, aspirin, glucose, bronchodilator; know protocols for syncope, allergic reaction, hypoglycemia, cardiac arrest.
Must Know
- American Society of Anesthesiologists (ASA) classification: ASA I (healthy) to ASA IV (severe systemic disease).
- Informed consent: discuss risks, benefits, alternatives; document verbal and written consent.
- Medical consultation: required for patients with uncontrolled systemic disease or complex medication regimens.
- Documentation: record medical history, vital signs, treatment plan, and any adverse events.
Clinical and Exam Application
- For hypertensive patients (BP >160/100), defer elective treatment and refer to physician.
- For diabetic patients, schedule morning appointments, monitor glucose, and watch for hypoglycemia.
- For patients on anticoagulants, use atraumatic technique, local hemostatics, and consider INR check.
High-Yield Distinctions
- ASA I vs. ASA II: ASA I has no disease; ASA II has mild controlled disease (e.g., well-controlled hypertension).
- Syncope vs. hypoglycemia: syncope has prodromal symptoms (lightheadedness, pallor); hypoglycemia has confusion, sweating, and rapid onset.
- Epinephrine in local anesthetic: contraindicated in severe cardiovascular disease (e.g., unstable angina, recent MI).
- MRONJ risk: higher with IV bisphosphonates (e.g., zoledronic acid) than oral; dental surgery is a trigger.
Common Pitfalls
- Failing to update medical history at each visit.
- Not taking vital signs before treatment.
- Assuming all anticoagulants require INR testing; DOACs do not require routine monitoring.
- Ignoring patient-reported allergies (e.g., latex, sulfa).
Review Tasks
- Practice taking and recording vital signs on a partner.
- Review emergency protocols for common scenarios (syncope, allergic reaction, hypoglycemia).
- Study ASA classification and treatment modifications.
- Role-play informed consent discussions.
Clinical Instrumentation and Deposit Removal
Syllabus Focus
- Instrument design and classification
- Scaling and root planing techniques
- Gracey curettes vs. universal curettes
- Sickle scalers and periodontal files
- Sharpening and maintenance
- Ergonomics and clinician positioning
Key Notes
- Gracey curettes are area-specific: each design has a specific shank angle for specific tooth surfaces (e.g., Gracey 11/12 for mesial of posterior teeth).
- Universal curettes (e.g., Columbia 13/14) can be used on all surfaces; the face is 90° to the shank.
- Sickle scalers have a triangular cross-section and are used for supragingival calculus; avoid subgingival use.
- Periodontal files are used for heavy calculus removal but can damage root surface if misused.
- Sharpening: maintain original blade angle (70° for curettes); use a sharpening stone and lubricant; test on plastic rod.
Must Know
- Correct grasp: modified pen grasp with fulcrum (intraoral or extraoral).
- Adaptation: blade face parallel to tooth surface; insert at 0° then angle to 45-90° for calculus removal.
- Stroke direction: vertical, oblique, or horizontal; use overlapping strokes.
- Assessment: use explorer to check for residual calculus; smooth root surface indicates complete planing.
Clinical and Exam Application
- Use Gracey 1/2 for anterior teeth, Gracey 13/14 for posterior mesial, Gracey 15/16 for posterior distal.
- For heavy supragingival calculus, use sickle scaler first then curette for fine scaling.
- Root planing: use light strokes with curette to remove embedded calculus and smooth cementum.
High-Yield Distinctions
- Gracey vs. universal: Gracey has a curved shank and face offset 60-70°; universal has face at 90°.
- Supragingival vs. subgingival scaling: supragingival uses sickles and curettes; subgingival uses curettes and files.
- Explorer types: #17 (straight), #23 (curved), #11/12 (pig-tail); used for detecting calculus and caries.
- Fulcrum: intraoral (on adjacent teeth) vs. extraoral (on chin or cheek); extraoral provides more stability for posterior areas.
Common Pitfalls
- Using a sickle scaler subgingivally, causing tissue trauma.
- Not maintaining a fulcrum, leading to uncontrolled strokes and patient injury.
- Overlapping strokes too wide, missing calculus deposits.
- Dull instruments causing burnishing of calculus instead of removal.
Review Tasks
- Practice instrument identification and classification.
- Sharpen a curette and test sharpness on a plastic rod.
- Perform scaling on a typodont with simulated calculus.
- Review ergonomic positioning to prevent clinician fatigue.
Pharmacology and Pain Control Modalities
Syllabus Focus
- Local anesthetics: types, dosages, and maximum doses
- Vasoconstrictors: indications and contraindications
- Analgesics: NSAIDs, acetaminophen, opioids
- Antibiotics: prophylaxis guidelines, common regimens
- Sedation and anxiety management
- Medical emergencies related to drugs
Key Notes
- Local anesthetics: amides (lidocaine, articaine, mepivacaine, bupivacaine) vs. esters (procaine, benzocaine); amides are more common and less allergenic.
- Maximum dose: lidocaine 2% with epinephrine 1:100,000 = 7 mg/kg (max 500 mg); articaine 4% = 7 mg/kg (max 500 mg).
- Vasoconstrictors (epinephrine, levonordefrin): prolong anesthesia, reduce toxicity; contraindicated in severe cardiovascular disease, hyperthyroidism, and with MAOIs.
- NSAIDs (ibuprofen, naproxen): analgesic, anti-inflammatory; contraindicated in GI ulcers, renal disease, and with anticoagulants.
- Antibiotic prophylaxis: AHA guidelines for infective endocarditis (high-risk cardiac conditions); ADA guidelines for prosthetic joints (generally not recommended).
Must Know
- Calculate maximum doses based on patient weight and concentration.
- Recognize signs of local anesthetic toxicity: CNS (tinnitus, metallic taste, seizures) and cardiovascular (arrhythmias, hypotension).
- Epinephrine reversal: if injected intravascularly, can cause tachycardia and hypertension; use aspiration to prevent.
- Antibiotic regimens: amoxicillin 2 g PO 1 hour before procedure; clindamycin 600 mg for penicillin allergy.
Clinical and Exam Application
- For patients with cardiovascular disease, use local anesthetic without vasoconstrictor (e.g., mepivacaine 3%) or with low epinephrine concentration.
- For prolonged procedures, use bupivacaine for long-acting anesthesia.
- For post-operative pain, prescribe ibuprofen 600 mg q6h or combination with acetaminophen.
High-Yield Distinctions
- Amide vs. ester: amides are metabolized in liver; esters in plasma by pseudocholinesterase.
- Lidocaine vs. articaine: articaine has higher lipid solubility and better bone penetration; max dose same.
- Epinephrine concentration: 1:100,000 = 0.01 mg/mL; 1:200,000 = 0.005 mg/mL.
- ASA guidelines: antibiotic prophylaxis no longer recommended for dental procedures in most patients with prosthetic joints.
Common Pitfalls
- Exceeding maximum dose, especially in children or low-weight patients.
- Not aspirating before injection, leading to intravascular injection.
- Using vasoconstrictor in patients with uncontrolled hypertension or hyperthyroidism.
- Prescribing NSAIDs to patients with renal impairment or GI bleeding risk.
Review Tasks
- Practice calculating maximum doses for different anesthetics and patient weights.
- Review AHA and ADA antibiotic prophylaxis guidelines.
- Study local anesthetic toxicity management (benzodiazepine for seizures, lipid emulsion for cardiac toxicity).
- Create a table of common drug interactions in dentistry.
Professional Ethics and Infection Control
Syllabus Focus
- Core ethical principles: autonomy, beneficence, nonmaleficence, justice
- Informed consent and patient confidentiality (HIPAA)
- Professional boundaries and scope of practice
- Standard precautions and transmission-based precautions
- Sterilization and disinfection protocols
- OSHA bloodborne pathogens standard
Key Notes
- Ethical principles: autonomy (patient's right to choose), beneficence (do good), nonmaleficence (do no harm), justice (fairness).
- Informed consent: must include diagnosis, treatment options, risks, benefits, alternatives; patient must be competent and consent voluntarily.
- HIPAA: protect patient health information; obtain authorization for disclosure; breach notification required.
- Standard precautions: treat all patients as potentially infectious; use PPE (gloves, mask, eyewear, gown).
- Sterilization: autoclave (steam under pressure) for heat-tolerant instruments; monitor with biological indicators (spore tests) weekly.
- OSHA: require exposure control plan, hepatitis B vaccination, post-exposure follow-up, and training.
Must Know
- Hand hygiene: before and after patient contact, after glove removal, after touching contaminated surfaces.
- Instrument processing: cleaning, packaging, sterilization, storage; use ultrasonic cleaner for debris removal.
- Surface disinfection: use EPA-registered hospital disinfectant with tuberculocidal claim; intermediate-level for clinical contact surfaces.
- Dental unit waterlines: treat to maintain <500 CFU/mL; use anti-retraction valves and shock treatments.
Clinical and Exam Application
- When a patient refuses treatment, document informed refusal and respect autonomy.
- If a needlestick injury occurs, wash wound, report, and follow post-exposure prophylaxis protocol.
- Use a chemical indicator (tape) on every sterilization pack; biological indicator weekly.
High-Yield Distinctions
- Sterilization vs. disinfection: sterilization kills all microorganisms including spores; disinfection kills most but not spores.
- Critical vs. semi-critical vs. non-critical instruments: critical (penetrate tissue) must be sterilized; semi-critical (contact mucous membrane) must be sterilized or high-level disinfected; non-critical (contact intact skin) require intermediate-level disinfection.
- Standard vs. transmission-based precautions: standard for all patients; transmission-based (contact, droplet, airborne) for known infections.
- OSHA vs. CDC: OSHA is regulatory (enforceable); CDC is guideline (recommendations).
Common Pitfalls
- Reusing single-use items (e.g., prophylaxis angles, saliva ejectors).
- Not changing gloves between patients or after touching contaminated surfaces.
- Improper storage of sterilized instruments (e.g., in open containers).
- Failing to document sterilization monitoring results.
Review Tasks
- Review CDC infection control summary and OSHA bloodborne pathogens standard.
- Practice proper hand hygiene and donning/doffing PPE.
- Study sterilization monitoring methods (chemical, biological).
- Role-play ethical scenarios (e.g., patient refuses radiographs).
How To Use These Notes With Practice Questions
Do not jump straight from reading to a full mock. Work by subject first: review the key notes, make a short recall sheet from memory, then answer a focused question set. After each miss, decide whether the problem was missing knowledge, poor clinical sequencing, weak source-rule recall, or a distractor you failed to eliminate.
Dental Conquer's question bank, flashcards, mind maps, and spaced review tools are most useful after this instruction layer because they reveal which parts of the notes are not yet retrievable.
Final Review Checklist
- Review all subject keyNotes and mustKnow items; focus on high-yield distinctions and common pitfalls.
- Practice clinical skills on typodonts and manikins to build muscle memory.
- Take practice exams under timed conditions to build stamina and identify weak areas.
- Review official source documents: DANB RHS outline, ADEX manuals, CDC guidelines, OSHA standards.
- Verify exam-specific details (dates, fees, eligibility) with CRDTS or ADEX testing agency.
- Create summary tables for drug doses, sterilization methods, and ethical principles.
- Form study groups to discuss clinical applications and review tasks.
Official Sources and Further Reading
Use these sources as the final authority for format, eligibility, rules, and exam updates. Study notes are a preparation layer, not a replacement for official candidate guidance.