MDS PREP
Which of the following statements is false?
1) The upper first premolar usually has two canals
2) Root canal instruments are best sterilized by a chemical method
3) All root canals must be enlarged to at least a size 25 file
4) All are false
Endodontics
Answer: 2
1) The upper first premolar usually has two canals: This statement is true. While the presence of two canals in the upper first premolar is not guaranteed, it is quite common to find two canals in this tooth.
2) Root canal instruments are best sterilized by a chemical method: This statement is false. The best method for sterilizing root canal instruments is heat sterilization using an autoclave. Chemical methods can be used for surface disinfection but are not adequate for sterilization.
3) All root canals must be enlarged to at least a size 25 file: This statement is true. Enlarging the root canals to a size 25 or larger is a part of the cleaning and shaping process in root canal therapy to ensure thorough debridement and preparation for filling.
The filling of choice for primary root canals
1. ZOE
2. Calcium hydroxide
3. Gutta-percha
4. Chlorpercha
Endodontics
Answer: 1
Zinc oxide eugenol is commonly used as a filling material for primary root canals due to its biocompatibility and sealing properties.
While combining NaOCH and H2O2 as irrigants
1) H2O2 should be used last
2) NaOCH should be used last
3) First irrigation should be done by normal saline
4) NaOCH and H2O2 should never be used simultaneously
Endodontics Answer: 2
Because residual H2O2 might react with debris and produce gas that can cause continuous pain.
Which condensation of gutta-percha, tip of the instrument is broken at apical third of canal. You would like to
1. Dissolve gutta-percha and retrieve the broken piece
2. Obturate remaining canal up to the point of obstruction, and observation
3. Do periapical surgery and apicectomy to remove broken piece
4. All of the above
Endodontics
Answer: 2
Finally, if the tip of the gutta-percha condensation instrument breaks in the
apical third of the root canal, the most common practice is to simply continue
with the obturation up to the point of obstruction. Attempting to dissolve the
gutta-percha or performing surgery to retrieve the broken piece may not be
necessary and can potentially cause further damage. Instead, the area is sealed,
and the body's natural healing processes are allowed to occur.
Most frequent failures of root canal treated cases are due to
1. Inadequate obturation
2. Improper sterilization
3. Improper preparation
4. All of the above
Endodontics
Answer: 1
The most frequent failures of root canal treated cases are often due to
inadequate obturation. This can occur when the root canal filling material does
not completely fill the space or when it is not properly compacted, leaving gaps
where bacteria can persist and cause reinfection. Proper preparation and
sterilization are also crucial, but inadequate obturation is the most common
technical error leading to treatment failure.
In periapical lesions of average size, time needed for osteogenesis is
1. 1-2 months
2. 2-6 months
3. 6-12 months
4. 2 weeks
Endodontics
Answer: 3
Osteogenesis in periapical lesions of average size generally requires a
significant amount of time, typically falling within the range of 6-12 months.
This period allows for the complete healing of bone tissue around the root apex.
Pulp exposures of crowns come under which class according to WHO nomenclature
1. 873.60
2. 873.61
3. 873.62
4. 873.63
Endodontics
Answer: 3
Explanation: According to the WHO classification of dental injuries, pulp exposures due to crown fractures are classified under 873.62. This classification helps in standardizing the terminology used in dental trauma, allowing for better communication and understanding among dental professionals.873.60 - Pulp Exposure due to TraumaThis code refers to cases where the pulp is exposed as a result of trauma to the tooth. It does not specify whether the pulp is vital or non-vital, but it indicates that there is a direct exposure of the pulp tissue.873.61 - Avulsion of ToothThis code is used for cases where a tooth has been completely displaced from its socket (avulsed). In avulsion cases, the pulp is typically exposed, and immediate re-implantation is critical for the best prognosis. This classification highlights the severity of the injury and the need for urgent treatment.873.62 - Crown Fracture with Pulp InvolvementThis code refers to fractures of the crown of the tooth that involve the pulp. It indicates that the fracture has extended into the pulp chamber, necessitating treatment such as root canal therapy.873.63 - Crown Fracture without Pulp InvolvementThis code is used for crown fractures that do not involve the pulp. In these cases, the injury is limited to the enamel and dentin, and the pulp remains intact.
Which of the following fractures of tooth was poorest prognosis
1) Horizontal fractures at gingival level
2) Vertical root fractures
3) Horizontal fractures at apical third of root
4) Horizontal fractures at middle third or root
Endodontics
Answer: 2
Vertical root fractures are often associated with a poor prognosis because they can lead to significant loss of tooth structure and are difficult to treat. They typically result in the need for extraction, especially if they extend into the periodontal ligament or if the fracture is not detected early.