Compared with the gingiva around a natural tooth, which feature of the peri-implant mucosa best explains why inflammation around an implant can spread toward the bone more rapidly?

Its connective tissue fibers run parallel to the implant surface and do not insert into it.

Its junctional epithelium attaches by desmosomes instead of hemidesmosomes and a basal lamina.

A periodontal ligament surrounds the implant and carries bacteria apically along the fixture.

It receives a richer blood supply because the ligament plexus is added to the supraperiosteal vessels.

Five weeks after scaling and root planing, a site that probed 6 mm with bleeding now probes 4 mm without bleeding. Which healing process mainly accounts for the improvement?

Gingival shrinkage and a long junctional epithelium adapted to the root

Creeping attachment of the gingival margin coronally over the root

New cementum, bone and periodontal ligament forming a new attachment

Regrowth of the alveolar crest to within 1-2 mm of the CEJ at that site

This patient takes glipizide 10 mg every morning before breakfast and works early shifts. Which appointment plan best reduces his risk of hypoglycemia during care?

A morning visit after he has eaten and taken his usual medications

A late-afternoon visit after his shift but before his evening meal

A morning visit before breakfast so that he arrives in a fasting state

Any time of day, provided he skips his glipizide dose that morning

Which statement about probing implant #30 in this patient is correct?

Light probing is appropriate, and the depths are compared with the baseline recorded at crown delivery.

Implants should never be probed, because any probing permanently destroys the peri-implant soft tissue seal.

Only a plastic probe may be used, because a metal probe always scratches the titanium surface.

Probing depths have no meaning around implants, because an implant has no cementoenamel junction.

NBDHE

Free NBDHE Practice Questions

10 sample questions for the NBDHE, with the correct answer and an explanation for each. No account needed. Try each one before you open the answer.

Sections covered on the exam: Microbiology, Immunology and Pathology, Physiology, Biochemistry and Nutrition, Care Planning, Patient Education, and Anxiety and Pain Control, Patient Assessment, Dental Radiography, Preventive Agents, Research Principles and Community Health, Infection Control, Medical Emergencies and Special Needs Patients.

Question 1 · Microbiology, Immunology and Pathology
A 58-year-old patient reports numbness of the left lower lip and chin, and the dentist notes that the left masseter feels weaker than the right on clenching. Imaging later shows a mass at the skull base. The mass most likely involves which opening?
- A.Foramen ovale
- B.Superior orbital fissure
- C.Stylomastoid foramen
- D.Foramen rotundum
Show answer and explanation
Answer: A. Foramen ovale
The mandibular division of the trigeminal nerve (V3) carries sensation from the lower lip and chin (through the inferior alveolar and mental nerves) and motor fibers to the muscles of mastication, and it leaves the skull through the foramen ovale. The foramen rotundum transmits V2, which is purely sensory to the midface, and the stylomastoid foramen transmits the facial nerve, which would affect facial expression rather than chewing.
Question 2 · Patient Assessment
An occlusal evaluation shows the mesiobuccal cusp of each maxillary first molar occluding mesial to the buccal groove of the mandibular first molar, retroclined maxillary central incisors with flared lateral incisors, and a deep overbite. This occlusion is classified as
- A.Angle Class I with crowding.
- B.Angle Class II, division 1.
- C.Angle Class III.
- D.Angle Class II, division 2.
Show answer and explanation
Answer: D. Angle Class II, division 2.
A distoclusion (the maxillary mesiobuccal cusp anterior to the mandibular buccal groove) is Angle Class II; retroclined central incisors with flared laterals and a deep bite define division 2. Division 1 has protruded maxillary incisors with a large overjet, and Class III places the mandibular molar mesial to normal.
Question 3 · Care Planning, Patient Education, and Anxiety and Pain Control
Compared with the gingiva around a natural tooth, which feature of the peri-implant mucosa best explains why inflammation around an implant can spread toward the bone more rapidly?
- A.Its connective tissue fibers run parallel to the implant surface and do not insert into it.
- B.Its junctional epithelium attaches by desmosomes instead of hemidesmosomes and a basal lamina.
- C.A periodontal ligament surrounds the implant and carries bacteria apically along the fixture.
- D.It receives a richer blood supply because the ligament plexus is added to the supraperiosteal vessels.
Show answer and explanation
Answer: A. Its connective tissue fibers run parallel to the implant surface and do not insert into it.
Around an implant, connective tissue fibers run parallel or circumferential to the surface without inserting into it, and there is no periodontal ligament and a reduced blood supply, so the soft tissue offers less of a barrier and peri-implant mucositis can progress to peri-implantitis quickly. The junctional epithelium still attaches by hemidesmosomes and an internal basal lamina, and implants have no periodontal ligament or ligament plexus.
Question 4 · Infection Control, Medical Emergencies and Special Needs Patients
Each of the following medications taken by this patient can contribute to her dry mouth EXCEPT one. Which one is the EXCEPTION?
- A.sertraline
- B.oxybutynin
- C.apixaban
- D.hydrochlorothiazide
Show answer and explanation
Answer: C. apixaban
Apixaban is an anticoagulant whose main dental concern is bleeding, not reduced salivary flow. Oxybutynin is a strongly anticholinergic bladder drug, hydrochlorothiazide is a diuretic, and sertraline is an antidepressant; all three are common causes of xerostomia, and together they explain her polypharmacy-related dry mouth.
Question 5 · Care Planning, Patient Education, and Anxiety and Pain Control
For this 46-year-old patient, the most severe site is the mesial of #19 with bone loss of about 50% of the root length. What is the percentage of bone loss divided by age, and what grade does it support?
- A.0.92, consistent with grade B
- B.0.011, consistent with grade A
- C.1.09, consistent with grade C
- D.1.09, consistent with grade B
Show answer and explanation
Answer: C. 1.09, consistent with grade C
The indirect evidence of progression is percentage bone loss at the worst site divided by age: 50 / 46 = 1.09. A ratio above 1.0 supports grade C, while 0.25-1.0 is grade B and below 0.25 is grade A. Dividing age by bone loss gives 0.92, and using 0.5 in place of 50 gives 0.011.
Question 6 · Microbiology, Immunology and Pathology
A patient cannot close the right eye, cannot wrinkle the right forehead and has a drooping right corner of the mouth, but sensation of the face is normal. A lesion of the nerve as it exits which opening best explains these findings?
- A.Foramen ovale
- B.Infraorbital foramen
- C.Stylomastoid foramen
- D.Jugular foramen
Show answer and explanation
Answer: C. Stylomastoid foramen
Paralysis of all the muscles of facial expression on one side with intact facial sensation points to the facial nerve (CN VII), which leaves the skull through the stylomastoid foramen before branching in the parotid gland. The foramen ovale transmits V3 (sensation and mastication), and the infraorbital foramen transmits sensory fibers of V2.
Question 7 · Patient Assessment
A 47-year-old patient has type 2 diabetes controlled with metformin (HbA1c 6.6%) and hypertension controlled with lisinopril (today 126/78 mm Hg). She walks 3 miles daily without symptoms. Her ASA Physical Status classification is
- A.ASA III.
- B.ASA II.
- C.ASA IV.
- D.ASA I.
Show answer and explanation
Answer: B. ASA II.
ASA II describes a patient with mild, well-controlled systemic disease without functional limitation, such as controlled diabetes and hypertension. ASA I is a normal healthy patient, ASA III involves severe systemic disease with functional limits (such as poorly controlled diabetes with complications), and ASA IV is a constant threat to life.
Question 8 · Care Planning, Patient Education, and Anxiety and Pain Control
Five weeks after scaling and root planing, a site that probed 6 mm with bleeding now probes 4 mm without bleeding. Which healing process mainly accounts for the improvement?
- A.Creeping attachment of the gingival margin coronally over the root
- B.New cementum, bone and periodontal ligament forming a new attachment
- C.Regrowth of the alveolar crest to within 1-2 mm of the CEJ at that site
- D.Gingival shrinkage and a long junctional epithelium adapted to the root
Show answer and explanation
Answer: D. Gingival shrinkage and a long junctional epithelium adapted to the root
After nonsurgical therapy, probing depths decrease mainly through resolution of edema (shrinkage, often seen as recession) and the formation of a long junctional epithelium against the cleaned root, which also resists probe penetration. True regeneration of cementum, ligament and bone does not follow debridement alone, and creeping attachment would reduce recession rather than pocket depth.
Question 9 · Infection Control, Medical Emergencies and Special Needs Patients
This patient takes glipizide 10 mg every morning before breakfast and works early shifts. Which appointment plan best reduces his risk of hypoglycemia during care?
- A.A late-afternoon visit after his shift but before his evening meal
- B.A morning visit before breakfast so that he arrives in a fasting state
- C.A morning visit after he has eaten and taken his usual medications
- D.Any time of day, provided he skips his glipizide dose that morning
Show answer and explanation
Answer: C. A morning visit after he has eaten and taken his usual medications
Glipizide is a sulfonylurea that stimulates insulin release and can cause hypoglycemia, so the safest plan is a morning appointment after a normal meal and his usual medications. Arriving fasting while the drug is active, or late in the day before a meal, raises the risk of low blood glucose. Patients should not alter prescribed diabetes medications on their own to fit a dental visit.
Question 10 · Care Planning, Patient Education, and Anxiety and Pain Control
Which statement about probing implant #30 in this patient is correct?
- A.Light probing is appropriate, and the depths are compared with the baseline recorded at crown delivery.
- B.Implants should never be probed, because any probing permanently destroys the peri-implant soft tissue seal.
- C.Only a plastic probe may be used, because a metal probe always scratches the titanium surface.
- D.Probing depths have no meaning around implants, because an implant has no cementoenamel junction.
Show answer and explanation
Answer: A. Light probing is appropriate, and the depths are compared with the baseline recorded at crown delivery.
Gentle probing with light force, compared with baseline depths recorded at crown delivery, is the main way to detect peri-implant disease, and the soft tissue seal reforms after probing. Light probing with either a plastic or a metal probe is acceptable; rough metal scalers, not probes, are the concern for implant surfaces, and a fixed reference point on the restoration replaces the CEJ.

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