Dentoalveolar questions OMSITE Flashcards
Osteogenesis occurs with which of the following grafting materials? A. Allogeneic bone grafts B. Xenographic bone grafts C. Alloplastic bone grafts D. Autogenous bone grafts
Answer: D
Rationale:
Osteogenesis refers to the growth of bone from viable cells transferred within the graft. Autogenous bone is the only graft material available with osteogenic properties.
Allogeneic bone grafts (allografts) are treated in bone banks in a variety of methods, resulting in different mineralized, freeze-dried, solvent-dehydrated, or demineralized states. Allografts such as demineralized freeze-dried bone and solvent-dehydrated mineralized bone have been advocated for use in extraction sites because of their osteoconductive nature and the characteristic that they will resorb and be replaced within a relatively short period of time.
Xenografts are graft materials harvested from a species other than human, typically bovine, and are processed to remove the antigenicity by a variety of chemical and preparation techniques. The absence of proteins results in minimal immune response in vivo.
Alloplasts include forms of calcium phosphate materialsóeither dense or porous hydroxylapatite, hard tissue replacement, and bioactive glass. These materials have proved useful for retaining alveolar bulk but can be slow to resorb because of their chemical characteristics. Recent advances in adding materials or changing the chemical characteristics of these materials, however, recently have been shown to provide maintenance of form and also allow for bone formation.
Reference:
Misch, CE, Contemporary Implant Dentistry 2nd edition, page 455, Mosby 1999.
Block, MS, Treatment of the single tooth extraction site. Oral and Maxillofacial Surgery Clinics of North America, Volume 16, Issue 1, February 2004, Pages 41-63
The phase in alveolar distraction osteogenesis for implant site development, which occurs at the end of distraction until the device is removed is known as the: A. latency period. B. distraction period. C. consolidation period. D. activation period.
Answer: C
Rationale:
The consolidation period follows active distraction and continues until device removal. The length of the consolidation period is influenced by the age of the patient, distance and time of distraction, and the amount of surgical trauma at the time of surgery. In cases of increased surgical trauma, recommendations are for increasing the time of the latency period and the consolidation period. The latency period is the time between device placement/osteotomy and activation of the distractor.
The distraction period is the classic term for the time frame during which the distraction device is activated and the gap between the osteotomy segments is expanded. The activation period could also describe the distraction period, but is not classic terminology.
Reference:
Batal H, Cottrell D. Alveolar distraction osteogenesis for implant site development. Oral Maxillofacial Surg Clin N Am 16 (2004) p.94.
Peterson, LJ, Ellis, E, Hupp, JR, Tucker, MR. Contemporary Oral and Maxillofacial Surgery 4th Edition, Mosby, St. Louis, 2003, p. 582-584.
Following completion of alveolar distraction, the stabilizing device is maintained for: A. 2 - 4 weeks. B. 5 - 7 weeks. C. 8 - 12 weeks. D. 13 - 17 weeks.
Answer: C
Rationale:
The ability of the distractor to stabilize the newly formed bone within the distraction gap is key to the formation of a healthy regenerate. Unstable devices are associated with increased endochondral bone formation and delayed bone formation within the distraction gap. Stable devices lead to direct osteogenesis without intervening cartilage formation.
Reference:
Batal H, Cottrell D. Alveolar distraction osteogenesis for implant site development. Oral Maxillofacial Surg Clin N Am 16 (2004) p.93 - 94.
Saulacić, N, MartÌn, M, Camacho, and GarcÌa, A Complications in Alveolar Distraction Osteogenesis: A Clinical Investigation
Journal of Oral and Maxillofacial Surgery, Volume 65, Issue 2, February 2007, Pages 267- 274
When performing alveolar ridge development using orthodontic forced eruption, what is the recommended amount of tooth movement per month? A. 1.0 - 2.0 mm B. 2.1 - 3.0 mm C. 3.1 - 4.0 mm D. 4.1 - 5.0 mm
Answer: A
Rationale:
The orthodontist needs to know what the clinician plans to gain by the forces applied to the tooth or teeth in the treatment area. Forces for crown lengthening would be rapid. By contrast, forced eruption for implant site development would be slower, approximately 1 to 2 mm per month. Caution should be taken to avoid moving the root too rapidly. In addition, the length of root in bone may affect the rate of movement and amount of applied force necessary. In a situation of severe bone loss, the remaining root in bone may be minimal (providing less resistance) and may move faster.
Reference:
Hinds K. Alveolar ridge development with forced eruption and distraction of retained natural dentition. Oral Maxillofacial Surg Clin N Am 16 (2004) p.76 - 78.
Mantzikos T, Shamus I. Forced eruption and implant site development: an osteophysiologic response. Am J Orthod Dentofacial Orthop 1999; 115(5):583ñ91.
When performing a ridge splitting technique to expand the edentulous ridge for insertion of an interpositional bone graft prior to implant placement, what is the preferred preoperative minimum ridge width? A. 1 mm B. 2 mm C. 3 mm D. 4 mm
Answer: C
Rationale:
The ridge splitting technique is used to expand the edentulous ridge for implant placement or insertion of an interpositional bone graft. This technique is only suitable for enhancing ridge width. There must be adequate available bone height for implant placement, and no vertical bone defect should be present. Although skilled surgeons may be able to expand very thin ridges, a minimum width of 3.0 mm is preferred. Splitting ridges narrower than this is technique sensitive and can result in bone fractures and resorption.
Reference:
Misch C. Implant site development using ridge splitting techniques. Oral Maxillofacial Surg Clin N Am (2004) p.65.
Fonseca, et al. Oral and Maxillofacial Surgery: Reconstructive and Implant Surgery: (Vol 7). Pages 219-221.
Which radiographic finding is most highly associated with inferior alveolar nerve exposure during surgical removal of mandibular third molars?
A. Darkening of the third molar tooth root
B. Narrowing of the third molar tooth root
C. Deflection of the third molar roots
D. Diversion of the inferior alveolar canal
Answer: A
Rationale:
IAN exposure is associated with increased incidence of IAN injury1. The radiographic finding linked with the most relative risk is darkening of the third molar tooth root 2. All other answers are associated with IAN exposure, but to a lesser amount.
Reference:
Valmaseda-Castellon E, Berini-Aytes L, Gay-Escoda C. Inferior alveolar nerve damage after lower third molar surgical extraction: a prospective study of 1117 surgical extractions. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2001; 92:377-383.
Sedaghatfar M, August MA, Dodson TB. Panoramic radiographic findings as predictors of inferior alveolar nerve exposure following third molar extraction. J Oral Maxillofac Surg. 2005; 63:3-7.
What is the frequency with which the lingual nerve runs superior to the lingual crest of the mandible? A. < 5% B. 10% C. 30% D. 50%
Answer: B
Rationale:
In a clinical study utilizing magnetic resonance imaging of the mandibles of normal human subjects, the lingual nerve was found to be on average 2.8mm inferior to the lingual crest and 2.5mm medial to the lingual plate. In 10% of the group, the lingual nerve was above the lingual crest and 25% were in direct contact to the lingual plate.
Reference:
Behnia H et al, An anatomic study of the lingual nerve in the third molar region.J Oral Maxillofacial Surg, 2000. 58:649.
Miloro M et al, Assessment of the lingual nerve in the third molar region using magnetic resonance imaging. J Oral Maxillofacial Surg, 1997. 55:134.
What is the most frequent postoperative complication of third molar extraction? A. Localized alveolar osteitis B. Subperiosteal abscess C. Inferior alveolar nerve injury D. Lingual nerve injury
Answer: A
Rationale:
In a prospective study involving 63 surgeons, 3,760 patients, and 8,333 third molars; it was found that the incidence of localized alveolar osteitis was 12% in mandibular molars. Other complication rates were: infection 1%, IAN injury 1.1-1.7%, Lingual nerve injury 0.3%.
Reference:
Haug, R, et al. The American Association of Oral and Maxillofacial Surgeons Age-Related Third Molar Study. JOMS 63:1106-1114, 2005
Dentoalveolar Surgery in Peterson’s Principles of Oral and Maxillofacial Surgery, Miloro, M. et al., Editors, Second Edition, BC Decker Inc, 2004, pp. 151.
While attempting to extract an impacted tooth #16, the tooth is suddenly displaced, and is no
longer visible or palpable. The patient now has limited mandibular opening. What is the most likely position of tooth #16?
A. In the maxillary sinus
B. In the buccal space
C. In the body of the zygoma
D. In the infratemporal space
Answer: D
Rationale:
Upper third molars can be displaced distally into the infratemporal space if excessive distal elevation is used without placement of retraction distal to the tooth. In this particular case, the new finding of restricted opening gives a clue that the tooth is not in the maxillary sinus, but most probably impinging on the coronoid process, and thus is in the infratemporal fossa.
Reference:
Dentoalveolar Surgery in Peterson’s Principles of Oral and Maxillofacial Surgery, Miloro, M. et al., Editors, Second Edition, BC Decker Inc, 2004, pp. 152.
Fonseca, et al. Oral and Maxillofacial Surgery: Anesthesia/Dentoalveolar Surgery/Office Management. (Vol 1). W.B. Saunders Company. Philadelphia. 2000. p426-427.
The posterior extension of an incision designed for removal of an impacted mandibular third molar is extended laterally because:
A. this design places the incision in keratinized tissue.
B. this design avoids injury to the buccal artery.
C. this design avoids injury to the lingual nerve.
D. this design reduces postoperative trismus.
Answer: C
Rationale:
The incision design for removal of impacted third molar flares laterally to avoid possible injury to the lingual nerve. The mandibular ramus flares laterally and the lingual nerve extends above the lingual crest 10% of the time.
Reference:
Ness GM, Peterson LJ. Impacted Teeth, p. 144. In Miloro M ed. Oral and Maxillofacial Surgery, vol. 1, BC Becker, 2004.
Miloro M, Halkias LE, Slone HW, Chakeres DW. Assessment of the lingual nerve in the third molar region using magnetic resonance imaging. J Oral Maxillofac Surg 1997;52:134-7.
The best approach for surgical exposure of an impacted tooth for orthodontic bracketing is:
A. complete exposure of the CEJ.
B. partial exposure of the crown and avoiding exposure of the CEJ.
C. complete exposure of the CEJ and 1 mm of surrounding alveolar bone.
D exposure of the crown until the greatest diameter of the crown is revealed regardless of the CEJ.
Answer: B
Rationale:
The surgical exposure of an impacted tooth should be carried out conservatively so that only enough bone and soft tissue is removed to place on orthodontic bracket. Damaging effects to the periodontium have been shown to be more frequent with exposure of the CEJ.
Reference:
Zeitler DL. Management of Impacted Teeth other than Third Molars, pp.133-134. In Miloro M ed. Oral and Maxillofacial Surgery, Vol. 1, BC Becker, 2004.
Kohavi D, Becker A, Silverman Y. Surgical exposure, orthodontic movement, and final tooth position as factors in periodontal breakdown of treated palatally impacted canines. Am J Orthod 1984; 85:72-77.
Bleeding encountered during exploration for this displaced, previously impacted, maxillary third molar would most likely emanate from the:
(picture of maxillary third molar in infra temporal fossa)
A. pterygoid venous plexus.
B. sphenopalatine artery.
C. descending palatine artery.
D. masseteric artery.
Answer: A
Rationale:
This scan depicts a tooth displaced into the infratemporal fossa. Maxillary third molars that are superiorly positioned may have only a thin layer of bone separating them from the infratemporal space. Venous bleeding from the pterygoid plexus of veins often makes visualization of the tooth difficult.
Reference:
Bouloux GF et al. Complications of Third Molar Surgery. Oral and Maxillofacial Surg Clin N Am 19 (2007), p. 122.
American Board of Oral and Maxillofacial Surgery
86
2008 Oral and Maxillofacial Surgery Self Assessment Tool (OMSSAT)
Pogrel M. Complications of Third Molar Surgery. Oral and Maxillofacial Surg Clin N Am 1990; 2:441.
The best time to provide intravenous preoperative antibiotic therapy prior to removal of impacted third molars associated with pericoronal infection is: A. immediately prior to surgery. B. 0.5-2 hours prior to surgery. C. 3-4 hours prior to surgery. D. 6 hours prior to surgery.
Answer: B
Rationale:
Prophylactic antibiotic therapy for asymptomatic impacted third molars in healthy patients is not indicated. For the compromised patient or one who is actively infected, antibiotic administration should be timed so that incision is performed at the peak systemic concentration.
Reference:
Mehrabi M, Allen JM, Roser SM.. Therapeutic Agents in Perioperative Third Molar Surgical Procedures. Oral Maxillofacial Surg Clin N Am 19(2007), p. 71.
Woods RK, Dellinger EP. Current guidelines for antibiotic prophylaxis of surgical wounds. Am Fam Physician 1998; 57 (11):2731-40.
When compared to areas grafted with palatal autografts, areas grafted with acellular dermal matrix allografts demonstrate which of the following qualities?
A. Less graft shrinkage and greater amounts of keratinized tissue
B. More graft shrinkage and greater amounts of keratinized tissue
C. Less graft shrinkage and lesser amounts of keratinized tissue
D. More graft shrinkage and lesser amounts of keratinized tissue
Answer: D
Rationale:
Acellular dermal matrix grafts act as a biologically compatible framework into which fibroblasts and epithelial cells can migrate and adhere, thus repopulating and incorporating the cells into the material. These migrating tissues replace the dermal matrix, causing increased graft shrinkage and ultimately resulting in lesser amounts of keratinized tissue at the recipient site.
Reference:
Yan JJ. Tsai AY. Wong MY. Hou LT. Int J Periodontics Restorative Dent. 2006 June; 26(3):287-92
McGuire MK. Nunn ME. Evaluation of the safety and efficacy of periodontal applications of a living tissue-engineered human fibroblast-derived dermal substitute. I. Comparison to the gingival autograft: a randomized controlled pilot study. Journal of Periodontology. 76(6):867-80, 2005 Jun.
Where keratinized gingival tissue exists, the best surgical option to thicken tissue around an implant to minimize facial metal show:
A. laterally repositioned flap.
B. semilunar flap.
C. free gingival graft.
D. subepithelial connective tissue graft.
Answer: D
Rationale:
There are several indications for the use of the subepithelial connective tissue graft and dental implant sites. Thickening gingiva to eliminate metal show from the underlying dental implant is one of these indications. The subepithelial connective tissue graft can thicken the gingiva one to 3 mm, depending on the thickness of the graft and contracture/shrinkage of the graft with healing.
Reference:
Block M S et al, Atlas of the Oral and Maxillofacial Surgery Clinics of North America. Soft Tissue Esthetic Procedures for Teeth Implants, Subepithelial Connective Tissue Grafting with Dental Implants. Pages 95-107, Volume Seven, Number Two, WB Saunders, 1999.
Block M S et al, Atlas of the Oral and Maxillofacial Surgery Clinics of North America. Soft Tissue Esthetic Procedures for Teeth Implants, A Subepithelial Connective Tissue Graft Procedure for Optimum Root Coverage. Pages 11-28, Volume Seven, Number Two, WB Saunders, 1999.
The biologic width refers to the distance between the:
A. gingival margin and the crestal bone.
B. base of the sulcus and the alveolar crest.
C. gingival margin and the junctional epithelium.
D. base of the sulcus and the cementoenamel junction.
Answer: B
Rationale:
The biologic width is defined as the distance from the base of the sulcus to the crest of the alveolar ridge. Accurate sulcus depth can be problematic to measure with implants since there is no direct connective tissue fiber insertion into the implant surface; so in theory a periodontal probe (especially of excessive pressure is used) can pass through the top of the implant epithelial attachment (the bottom of the sulcus) to the top of the alveolar ridge crest. Biologic width (usually at least 2mm) is maintained between any microgap in the fixture/abutment interface.
Reference:
Misch, CE, Dental Implant Prosthetics, pages 74-75, Mosby, Inc. 2005.
Fonseca, R J et al, Oral and Maxillofacial Surgery Volume Seven, Soft Tissue Considerations, page 341, WB Saunders 2000.
For a subantral osseous augmentation, non-resorbable HA is added to autogenous bone in order to:
A. add bulk to the graft.
B. improve initial implant stability. C. decrease infection rate.
D. improve osteogenesis.
Answer: A
Rationale:
When mixed to a 1:1 ratio with an allograft or autograft, nonresorbable hydroxyapatite helps compensate for the nature loss of bone volume that is seen with the grafts alone. It is also stable in its volume independently and therefore acts as a latticework providing structural support.
Reference:
Babbush, CA, Dental Implants: The Art and Science, WB Saunders, 2001, pp 158-9 Block, MS: Treatment of the single tooth extraction site, Oral Maxillofacial Surg Clin N Am 16 (2004) 41ñ63
Local contraindications to a four-millimeter diameter posterior single tooth implant include:
A. an adjacent tooth that requires a crown.
B. mesiodistal bone width <7mm.
Answer: B
Rationale:
Contraindications to implant placement in this situation include inadequate bone volume of <7mm in the mesiodistal direction. Also, more than one adjacent tooth of a moderate to advanced mobility is considered unacceptable. Both adjacent teeth requiring crowns is a relative indication for a fixed partial denture restoration (influenced by the long-term prognosis of the adjacent tooth or teeth.)
Reference:
Misch, CE, Dental Implant Prosthetics, Mosby, 2005, pp 354-5
Manual of Dental Implants: David P. Sarment, D.D. S., M.S., page 14
Fonseca, et al. Oral and Maxillofacial Surgery: Reconstructive and Implant Surgery: (Vol 7). Pages 211-242.
Which of the following is a limitation of the palatal connective tissue graft technique?
A. High incidence of poor healing
B. Dependence on smooth palate donor site
C. Graft availability is dependent on donor site thickness
D. High incidence of neurovascular injury
Answer: C
Rationale:
Connective tissue grafting extremely useful in that is does not depend upon a smooth palate and heals very well. The incidence of neurovascular injury is also very low if harvested in the classic manner (anterior to the maxillary first molar.) Depending upon the thickness of a particular patient’s tissue, the amount of graft available may be minimal and therefore some patients may require secondary grafting several months later.
Reference:
Sclar A, Alpha Omegan, Volume 93, number3, Aug/Sept 2000, pg 38-46.
Fonseca, et al. Oral and Maxillofacial Surgery: Reconstruction and Implant Surgery. (Vol 7). WB Saunders Company. Philadelphia. 2000, pp 335-8.
Which of the following is considered the least beneficial transport medium in the management of avulsed permanent teeth? A. Milk B. Saliva C. Hankís solution D. Blood
Answer: D
Rationale:
Acceptable transport media for avulsed permanent teeth include Hank’s balanced salt solution, milk, saliva (vestibule), saline, and water (if none of the above is available). Blood is not an acceptable form of transport media according to the recommended guidelines of the American Association of Endodontists since it does not replenish PDL cellular metabolites. Hank’s solution is a balanced salt solution with a physiologic pH.
Reference:
Recommended Guidelines of the American Association of Endodontists
Peterson’s Principles of Oral and Maxillofacial Surgery Vol 1; Management of Alveolar and Dental fractures, BC Decker 2004
Which of the following is contraindicated true regarding replantation of avulsed teeth?
A. Primary teeth can be replanted within 1-2 hours following avulsion
B. Ankylosis following replantation of teeth is a rare complication
C. Avulsed teeth should be followed for at least 5 years to determine outcome of teeth
D. Rigid splinting is recommended in most cases following replantation of avulsed teeth
Answer: C
Rationale:
Primary teeth should not be replanted following avulsive injuries. Space maintenance is however recommended in these situations. Replantation of avulsed primary teeth may cause risk of pulp necrosis and interference with development of succedaneous teeth.
Reference:
Recommended Guidelines of the American Association of Endodontists
Fonseca Oral and Maxillofacial Trauma Vol 1; Diagnosis and Management of Dentoalveolar Injuries p 427-478, Elsevier Saunders 2005
How long should subluxed permanent teeth be treated with a flexible splint? A. 1-2 weeks B. 3-4 weeks C. 5-6 weeks D. 7-8 weeks
Answer: A
Rationale:
A flexible splint (acid-etched) should be used for 7 to 10 days on subluxed permanent teeth. A short period of time is preferred to a longer period of time in order to prevent future complications such as ankylosis. Subluxation is the defined as movement of the teeth in any direction while concussion is the physiologic/pathologic sequela of a subluxation that affects the pulpal tissue and surround PDL.
Reference:
Kaban LB, et. al. Pediatric Oral and Maxillofacial Surgery. Ch. 25 Facial Trauma II: Dentoalveolar Injuries and Mandibular Fractures, Baumann A, et. al. p.446.
Daniels A, Backland L: Traumatic Dental Injuries: Current Treatment Concepts. JADA 129 (10):1401-14 1998OK
Which of the following is true regarding avulsed teeth?
A. Permanent teeth with apical foramina less than 1 mm diameter have a better prognosis than those with greater an 1 mm diameter
B. Avulsed permanent teeth stored in Hankís solution have a more guarded prognosis than those stored in saline
C. Replanted permanent teeth should be treated with a rigid splint
D. Avulsed primary teeth are not replanted
Answer: D
Rationale:
Permanent teeth with open apices greater than 1 mm diameter have a much better prognosis than those with closed apices since there is increased potential for reestablishment of pulpal circulation. Hank’s solution is considered the ideal physiologic medium for avulsed teeth.
It contains sodium chloride, calcium chloride, potassium chloride and magnesium sulfate. Avulsed primary teeth are never replanted since they have poor prognosis and may cause ankylosis of the permanent tooth.
Reference:
Fonseca. Oral and Maxillofacial Trauma. Diagnosis and management of dentoalveolar injuries, p 427-478, 2005.
OMS Reference Guide, Trauma/Emergencies, p 149-182, 2007.
Which type of injury to teeth carries the highest degree of pulpal necrosis? A. Extrusion B. Intrusion C. Lateral luxation D. Lingual luxation
Answer: B
Rationale:
Intrusive type injuries to teeth will cause greater compression and inflammatory injury of the periapical tissues and therefore greater compromise of the pulpal vasculature and blood flow causing an incidence of 65-90% pulpal necrosis. Extrusion can cause pulpal necrosis in 64% of the time; Luxations account for the lowest incident of pulpal necrosis.
Reference:
Fonseca. Oral and Maxillofacial Trauma. Diagnosis and management of dentoalveolar injuries, p 427-478, 2005.
Peterson. Principles of Oral and Maxillofacial Surgery. Management of alveolar and dental fractures, p 383-400, 2006.
Andreasen JO. Luxation of permanent teeth due to trauma: a clinical and radiographic follow-up study of 189 injured teeth. Scan J Dent Res 1970, 78: 273.
Which of the following root fractures has the best prognosis?
A. Horizontal fracture in the apical 1/3 of the root
B. Horizontal fracture in the coronal 1/3 of the root
C. Horizontal fracture in the middle portion of the root
D. Vertical fracture of the root
Answer: A
Rationale:
Fractures in the apical 1/3 of roots have the best prognosis for survival since the apical portion of the root is completely embedded in alveolar bone and surrounding PDL.Serial follow up evaluations are indicated. In many instances, endodontic therapy may not be indicated. Vertical root fractures require extraction since the entire pulp chamber is injured in this type of fracture.
Reference:
Fonseca. Oral and Maxillofacial Trauma. Diagnosis and management of dentoalveolar injuries, p 427-478, 2005.
Peterson. Principles of Oral and Maxillofacial Surgery. Management of alveolar and dental fractures, p 383-400, 2006.
What is the recommended treatment for permanent teeth with vertical root fractures? A. Splinting the teeth for 2 weeks B. Splinting the teeth for 6 weeks C. No treatment is necessary D. Extraction
Answer: D
Rationale:
All primary and permanent teeth with vertical root fractures must be extracted. These teeth have poor prognosis.
Reference:
Fonseca. Oral and Maxillofacial Trauma. Diagnosis and management of dentoalveolar injuries, p 427-478, 2005.
Peterson. Principles of Oral and Maxillofacial Surgery. Management of alveolar and dental fractures, p 383-400, 2006.
During extraction of erupted premolars to facilitate orthodontics, which tooth is most likely to have a root fracture during extraction? A. Maxillary first premolar B. Maxillary second premolar C. Mandibular first premolar D. Maxillary second premolar
Answer: A
Rationale:
The maxillary first premolar root usually bifurcates into buccal and palatal roots which are often thin and slightly curved. This predisposes this premolar to root fractures with extraction. Maxillary second premolars and mandibular first and second premolars usually have single roots.
Which of the following factors would be most important in deciding to remove a 2mm fractured root tip of a maxillary molar?
A. Close proximity of the root tip to the floor of the maxillary sinus
B. Patientís age less than 50
C. Operator skill and experience
D. Presence of periapical pathology with the root tip
Answer: D
Rationale:
In general, roots with periapical lesions should be removed whenever possible, even if they are near the maxillary sinus floor. The patient’s age less than 50 should not be a factor in the decision. All OMSs should possess adequate skill and experience to remove root tips.
Which of the following conditions are most likely to be associated with an asymptomatic erupted mandibular third molar in a young adult?
A. Resorption of the distal root of the adjacent tooth
B. Dental caries
C. Loss of periodontal support
D. Dentigerous cysts
Answer: C
Rationale:
The most common problems associated with retained third molars are loss of periodontal support on the adjacent second molar and pericoronitis.
Numerous studies have documented the presence of periodontal pathogens and loss of periodontal support at the distal of the second molar and third molar. This condition has been shown to progress with age. Acute pericoronitis is also a relatively common finding and if third molars are not removed, the condition is likely to recur and / or occur with another third molar. 60% of patients with pericoronitis experienced symptoms associated with the contralateral third molar within the previous 12 months.
Other types of pathology such as resorption of adjacent tooth roots or odontogenic cysts are less common.
Which of the following is an indication to perform a sulcular incision instead of a scalloped mucogingival junction incision when performing periapical surgery on a maxillary incisor?
A. Presence of a short root
B. Preserving anterior gingival esthetics
C. Avoidance of releasing incisions
D. Eliminate the need for suturing
Answer: A
Rationale:
Typically, in the anterior region where esthetics is a concern, a scalloped submarginal incision is preferred. However, contraindications to this approach are periodontal breakdown, a large periapical lesion, and a short root. In these cases, a full thickness sulcular incision with one or two releasing incisions is preferred. A sulcular incision may also used to avoid placing an incision over an underlying bony defect.
Which of the following factors are associated with a favorable outcome when uprighting second molars?
A. Uprighting involving an arc of rotation of greater than 90 degrees
B. Incomplete vertical growth of the mandible
C. The need to correct the bucco-lingual position of the tooth
D. Second molar root formation is 2/3 complete
Answer: D
Rationale:
Incomplete root formation is a favorable factor when repositioning a tooth. All the other factors listed would increase the difficulty of uprighting the second molar. The procedure is best performed after 2/3 of root development is completed. At this stage the risk of root fracture is minimal. Performing this procedure when less than 2/3 of root development has been completed could result in the second molar floating in its new position. Although the procedure has been performed when root development is complete, the incidence of subsequent pulpal necrosis or calcification is increased.
The CT scans below are of a patient who presented to the emergency department with a history of instantaneous painless swelling during surgical extraction of an erupted maxillary molar by a general dentist. What is the most appropriate management? (air emphysema) A. Observation B. Transcutaneous puncture aspiration C. Arteriogram & selective embolization D. Surgical exploration
Answer: A
Rationale:
The CT scan depicts air emphysema. Although hemorrhage should be included in the differential diagnosis, the scan clearly depicts air and not blood. Most cases of surgical emphysema following dental treatment (72%) involved the use of high-speed air-turbine drills and air syringes. Surgical emphysema is characterized by soft tissue swelling of sudden onset, usually developing within seconds or minutes. Palpation of the affected tissues shows crepitus or crackling, an important diagnostic feature. Discomfort is a variable finding. Some patients complain of severe pain, but usually the discomfort is mild and resolves within a few days. Most cases of subcutaneous emphysema will begin to resolve after 2 to 3 days of supportive treatment, and residual swelling is usually minimal after 7 to 10 days of observation. Treatment is usually conservative, and consists of antibiotic coverage to prevent infection. Oral bacteria may possibly be carried with the aerosol into the soft tissue and represent a potential nidus of infection. Additionally, a course of systemic corticosteroids may promote faster resolution. Surgical decompression of the extensive emphysema should not be routinely used, because it is likely to be ineffective and may even worsen or spread the emphysema.
The most frequent location for an impacted supernumerary tooth is: A. maxillary central incisor region. B. maxillary canine region. C. maxillary third molar region. D. mandibular premolar region.
Answer: A
Rationale:
The most frequent site for supernumerary teeth is the maxillary central region, followed by the maxillary lateral incisor region and the maxillary canine region.
Which tooth orientation is generally the most difficult mandibular third molar impaction to remove? A. Mesioangular B. Distoangular C. Horizontal D. Vertical
Answer: B
Rationale:
The distoangular impaction is the most difficult mandibular third molar to remove owing to the path of delivery into the ascending ramus. This situation often necessitates a considerable amount of ostectomy and multiple sectioning of the tooth.
Coronectomy is an alternative technique for the management of an impacted mandibular third molar when:
A. there is periapical infection.
B. the tooth is mobile.
C. the root is intimately associated with the inferior alveolar nerve.
D. the tooth is horizontally impacted along the course of the inferior alveolar nerve.
Answer: C
Rationale:
Coronectomy is a viable technique in those cases where removal of an impacted third molar might put the inferior alveolar nerve at considerable risk of damage. Infection, tooth mobility, and horizontally impacted teeth adjacent to the nerve are contraindications for this technique.
The best technique for performance of a partial odontectomy (coronectomy) is to remove tooth structure:
A. to a level approximately 3 mm above the level of the inferior alveolar canal and healing by secondary intention.
B. so that the remaining roots are at least 3 mm below the crestal bone followed by healing by secondary intention.
C. so that the remaining roots are at least 3mm below the crestal bone followed by watertight primary closure.
D. to a level approximately 3 mm above the level of the inferior alveolar canal followed by watertight primary closure.
Answer: C
Rationale:
The problem of inferior alveolar nerve involvement during the removal of lower third molars is a clinical and, more recently, medicolegal issue. Because the results of damage to the inferior alveolar nerve are unpredictable in that many cases do recover but some do not, it is preferable to carry out a technique that may reduce the possibility of this involvement. The technique of coronectomy, partial odontectomy, or deliberate root retention, is one such technique. The best technique for partial odontectomy involves sectioning of the tooth at a 45 degree angle (as measured bucco-lingually) followed by further reduction to reduce the remaining fragments 3 mm below the crestal bone level. The distance of 3 mm has been validated by animal studies to allow bone formation over the retained root fragments. Primary closure is indicated to reduce the risk of postoperative infection.
The technique of coronectomy seems to be a safe and straightforward technique with few complications or potential complications. In Pogrel’s series, there has only been one case of mild, transient (5 days) lingual paresthesia, presumably caused by the lingual retraction, but no other cases of lingual nerve involvement were reported. Other studies, however, have suggested a higher rate of transient lingual paresthesias from the use of the lingual retractor but not permanent cases of lingual nerve involvement. There does not seem to be any need to treat the exposed pulp of the tooth, and root treatment actually seems to be contraindicated. Animal studies have shown that vital roots remain vital with minimal degenerative changes.
The best time to provide intravenous preoperative antibiotic therapy prior to removal of impacted third molars associated with pericoronal infection is: A. immediately prior to surgery. B. 0.5-2 hours prior to surgery. C. 3-4 hours prior to surgery. D. 6 hours prior to surgery.
Answer: B
Rationale:
Prophylactic antibiotic therapy for asymptomatic impacted third molars in healthy patients is not indicated. For the compromised patient or one who is actively infected, antibiotic administration should be timed so that incision is performed at the peak systemic concentration.
Bleeding encountered during exploration for this displaced, previously impacted (infra temporal space), maxillary third molar would most likely emanate from the: A. pterygoid venous plexus. B. sphenopalatine artery. C. descending palatine artery. D. masseteric artery.
Answer: A
Rationale:
This scan depicts a tooth displaced into the infratemporal fossa. Maxillary third molars that are superiorly positioned may have only a thin layer of bone separating them from the infratemporal space. Venous bleeding from the pterygoid plexus of veins often makes visualization of the tooth difficult.
