NBDHE cheat sheet

Enamel by weight is about 96% inorganic hydroxyapatite, 1% organic, and 3% water; dentin is about 70% inorganic, 20% organic (mostly type I collagen), and 10% water; cementum is roughly 45-50% inorganic.

Principal periodontal ligament fiber groups from crest to apex: transseptal, alveolar crest, horizontal, oblique (most numerous and resists axially directed forces), apical, and interradicular.

Eruption timing: primary mandibular central incisor at 6-10 months; permanent first molar and mandibular central incisor at 6-7 years; second molar at 12-13 years; third molar at 17-21 years.

Muscles of mastication (masseter, temporalis, medial pterygoid, lateral pterygoid) are innervated by the mandibular division of the trigeminal nerve; the lateral pterygoid depresses and protrudes the mandible.

Caries microbiology: Streptococcus mutans initiates the lesion, Lactobacillus and other aciduric species dominate advanced lesions, and sucrose is the most cariogenic dietary sugar.

Periodontal pathogens: the red complex is Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola; Aggregatibacter actinomycetemcomitans is associated with localized aggressive periodontitis.

Amide local anesthetics (lidocaine, mepivacaine, articaine) are metabolized in the liver; ester anesthetics (procaine, benzocaine) are hydrolyzed by plasma pseudocholinesterase and carry a higher allergy risk.

Vasoconstrictor limit for a healthy adult is 0.2 mg epinephrine, equal to about 11 cartridges of 1:100,000 epinephrine (0.018 mg per 1.8-mL cartridge); the cardiac limit is 0.04 mg.

Calcium homeostasis: parathyroid hormone raises serum calcium through bone resorption, renal tubular reabsorption, and activation of vitamin D; calcitonin lowers serum calcium; vitamin D increases intestinal calcium absorption.

Probing interpretation: 1-3 mm indicates a healthy sulcus; 4 mm or greater with bleeding on probing indicates inflammation; clinical attachment level equals probing depth plus recession measured from the cementoenamel junction.

Gracey curets are area-specific with one cutting edge and a rounded toe: 1-2 and 3-4 anterior, 5-6 anterior, 7-8 posterior facial, 9-10 posterior facial, 11-12 posterior mesial, 13-14 posterior distal.

Universal curets have two cutting edges and a rounded toe and may be used on all tooth surfaces; sickle scalers have a pointed tip and are restricted to supragingival use.

Fluoride products: 1.23% acidulated phosphate fluoride gel or foam (about 12,300 ppm F) applied for 4 minutes; 5% sodium fluoride varnish (about 22,600 ppm F); 38% silver diamine fluoride to arrest active caries.

Sealant technique: isolate the tooth, etch 15-20 seconds on permanent teeth or 30 seconds on primary teeth, rinse and dry, keep the field contamination-free, then place and light-cure the sealant and verify retention at recall.

Radiographic principles: the paralleling technique minimizes distortion, bitewings detect interproximal caries, and ALARA requires clinical justification, F-speed film or digital sensors, and lead apron with thyroid collar.

Periodontal charting: furcation involvement graded Glickman I-IV, mobility graded 0-3 by Miller, and bleeding on probing that persists at repeated visits predicts disease progression.

Local anesthesia technique: always aspirate before depositing solution; 1:100,000 epinephrine prolongs anesthesia and provides hemostasis; never exceed the calculated maximum dose based on patient weight and medical status.

Medical emergencies: syncope is the most common event and is managed by placing the patient supine with legs elevated; elective care is deferred when blood pressure is 180/110 mm Hg or higher.

Prevalence equals all existing cases divided by the total population at one point in time; incidence equals new cases divided by the population at risk over a defined period.

Sensitivity equals true positives divided by true positives plus false negatives; specificity equals true negatives divided by true negatives plus false positives; positive predictive value rises as disease prevalence rises.

Relative risk is calculated in cohort studies as incidence in exposed divided by incidence in unexposed; the odds ratio is the association measure used in case-control studies.

Hierarchy for causal inference: randomized controlled trial, prospective cohort, case-control, cross-sectional survey, then case report.

Levels of prevention: primary acts before disease onset (water fluoridation, sealants, vaccines), secondary detects and treats early disease (screening), tertiary limits disability (rehabilitation, prosthetics).

Common dental indices: DMFT and dmft for caries experience, Silness-Loe and O'Leary for plaque, Loe-Silness for gingivitis, Dean's index for fluorosis, and the WHO CPI for periodontal status.

Optimal community water fluoride concentration in the United States is 0.7 mg/L; the risk of moderate fluorosis rises as water concentration approaches and exceeds 2 mg/L.

Biases to recognize: selection bias from nonrandom group assignment, recall bias from differential memory, measurement bias from observers, lead-time bias from earlier detection, and the Hawthorne effect from being observed.

Statistical significance is conventionally set at p less than 0.05, but clinical significance depends on effect size and confidence interval width rather than the p value alone.