Traumatology

Question 1

Q229 : Following a lateral luxation injury, what are the chances that a tooth will maintain its pulp vitality?

Answer 1

There is a 60- 75% chance that a tooth can maintain its vitality following a lateral luxation injury. The vital pulp may undergo calcification in 25-40% of the cases** (Ferrazzini Pozzi & Von Arx, Dental Traumatol - 2008, Nikoui et al, Dent traumatol - 2003)**.
It should be noted that the change of survival of the pulp relies to a great extent on the stage of root development Roots with closed apex are more likely to develop pulp necrosis following lateral luxation and repositioning.

Question 2

Q230 : Which of the following predisposing factors is the most associated with invasive cervical root resorption?
Orthodontic treatment / Dental trauma / Internal bleaching / Periodontal treatment

Answer 2

According to Heithersay (Quintessence Int - 1999), of the potential predisposing factors causing invasive cervical root resorption:
- 24.1% from orthodontic treatment
- 15.1% from dental trauma
- 14.4% Intra-coronal restorations
- 5.4% from oral surgical procedures
- 3.9% from intra-coronal bleaching
- 16.4% - no identifiable predisposing factor

Question 3

Q231 : What are the probabilities of pulp revascularization following avulsion and replantation of permanent teeth? and what are the factors affecting this type of healing?

Answer 3

Andreason et al. (Endod Dent Traumatol - 1995) showed that the pulps of around 34% of replanted permanent teeth can revascularize.
Factors affecting pulp revascularization:
a) Immediate placement (less than 5 mins)
b) Immature teeth
c) Teeth with shorter distances from the apical foramen to the pulp horns

Question 4

Q230 : Which of the following is more important for the success of replanted avulsed tooth?
PDL in the socket // PDL on the root surface

Answer 4

Oswald et al. (JOE - 1980) & Van Hassel et al. (JOE - 1980), in a 2-part study, showed that the viability of the PDL on the root surface is far more important than the viability of the PDL in the socket for the success of replanted avulsed teeth.

Question 5

Q231 : How to minimize root resorption following replantation of an avulsed tooth?

Answer 5

1- Flexible splinting
2- Avoid long term splinting (not more than 1 month) (Nasjleti et al, Oral Surg - 1982).
3- Systemic Tetracycline antibiotics since it has anti-resorptive properties. lt could be an alternative to amoxicillin after avulsion injuries (Sae-Lim et al, Dent Traumatol - 1998).
4- Topical use of dexamethasone has been shown to enhances healing and results in fewer resorption complications (Sae-Lim et al, Dent Traumatol - 1998).

Question 6

Q232 : Explain how internal root resorption can be triggered and propagate?

Answer 6

According to Tronstad (Dent Traumatology - 1988) : Damage to the predentin layer due to:
a) Low-grade irritation of the pulpal tissue localized to a small area of the root canal, i.e. chronic irreversible pulpitis or partial necrosis.
b) trauma or application of extreme heat to the tooth.
- The pulpal tissue apical to the resorptive lesion must have a viable blood supply to provide nutrition to the clastic cells.
- Infected, necrotic, coronal pulp tissue provides stimulation for those clastic cells.
- Bacterial is required to sustain the pathologic process
In an experimental model by Wedenberg & Lindskog (Dent Traumatol - 1985), it was suggested that internal resorption may be divided into a transient type and a progressive type, the latter requiring a continuous stimulation by infection.
Internal resorption may be associated with resorption of the dentin and a subsequent deposition of hard tissue that resembles bone or cementum but not dentin (Haapasalo & Endal, Endodontic Topics — 2006).

Question 7

Q233 : How can internal bleaching causes cervical root resorption?

Answer 7

The underlying mechanism for this effect is unclear, but it has been suggested that the bleaching agent reaches the periodontal tissue through the dentinal tubules and initiates an inflammatory reaction (Cvek & Lindvall, Dent Traumatol - 1985).
It has also been speculated that the peroxide, by diffusing through the dentinal tubules, denatures the dentin, which then becomes an immunologically different tissue and is attacked as a foreign body.

Question 8

Q234 : What type of splint should be used to stabilize teeth with horizontal root fracture & why?

Answer 8

• Flexible splint
• Experimental studies in non-human primates have demonstrated that rigid splinting or prolonged splinting may lead to PDL healing complications (i.e. ankylosis or external root resorption) (Nasjleti et al, Oral Surg - 1982).

Question 9

Q235 : Which of the following traumatic injuries is more susceptible to develop external Inflammatory root resorption?
Concussion / Subluxation / Lateral luxation / Intrusion

Answer 9

Andreasen & Pedersen (Dent Traumatol — 1985) showed that in 637 permanent luxated teeth with up to 10 years follow up, external inflammatory resorption was highest in intrusive luxation injuries (38%). All other injuries had very low incidence of resorption:
- No resorption cases after concussion injuries
- 0.5% after subluxation injuries
- 3% of laterally luxated teeth
- 6% of extrusively luxated teeth
- 38% with intrusion
In a study similar, Crona-Larsson et al. (Dent Traumatol - 1991) showed that in 171 traumatized teeth, the highest incident of external inflammatory root resorption was associated with extrusively luxated teeth (60%) followed by intruded teeth (22%).

Question 10

Q236 : What is the success rate of treating “Heithersay type IV” invasive cervical root resorption (ICRR)?
40% / 32% / 21% / 12%

Answer 10

Heithersay (Quintessence Int - 1999) investigated the treatment outcome of out of 101 cases of ICRR in 94 patients
Class l and Il lesions had a 100% success rate when treated.
Class Ill lesions: 77.8% success
Class IV lesions: 12.5% success

Question 11

Q237 : What are the different types of healing that can be achieved following horizontal root fracture?

Answer 11

According to Cvek et al. (Dent Trauamtol - 2001), there are 4 different types of healing that can be achieved following horizontal root fracture:
1) Hard tissue healing
2) PDL healing
3) Hard issue + PDL healing
4) No healing

Question 12

Q238 : What are the factors that may contribute to root resorption?

Answer 12

According to a review by Sak et al. (MicroMedicine - 2016) factors that may result in root resorption can be classified to local factors and systemic factors:
Local factors
1) Trauma
2) Internal Bleaching
3) Pulp necrosis
4) Orthodontic treatment
5) Periodontal treatment
6) pressure from a tumor or cyst
7) Dental abnormalities, e.g. invaginated teeth
8) others

Systemic factors
1) Scleroderma
2) Hormone dysregulation (hyperthyroidism and hypoparathyroidism)
3) Pregnancy
4) Kidney disease
5) Radiotherapy
6) Vitamin A deficiency
7) Hypertension
8) Paget’s disease
9) others

Question 13

Q239 : Which of the following injuries have the highest incidence of pulp necrosis?
Concussion / Subluxation / Intrusion / Lateral luxation

Answer 13

Tsilingaridis et al. (Dent Traumatol - 2016) evaluate the survival of intruded permanent teeth related to treatment in a large number of patients, with special focus on development on pulp necrosis and replacement resorption. Pulp necrosis was diagnosed in 75%, infection-related root resorption in 25% and replacement resorption in 22%. Root development and degree of intrusion may be important for the development of pulp necrosis and replacement resorption.

Question 14

Q240 : Describe the different stages of invasive cervical root resorption?

Answer 14

According to Mavridou et al. (JOE - 2016), invasive cervical root resorption can be characterized to 3 different stages:
1) Resorption initiation (injury of the PDL with localized inflammation)
2) Resorption progression: Pericanalar resorption resistant sheet (PRRS) (known as pre-dentin) protects the pulp from resorption either through maintaining normal oxygen content inside the pulp or with its higher mineral content compared to the surrounding dentin
3) Repair Stage: Signs of active and dynamic remodeling of the reparative bone-like tissue were visible; active resorption of dentin, active repair by osteoid formation and remodeling of bone-like tissue were observed to occur simultaneously at different areas of the tooth.

Question 15

Q241 : What are the clinical factors that can contribute to periodontal healing without resorption following avulsion?

Answer 15

Andreasen et al (Dent Traumatol — 1995) found 4 factors that can contribute to periodontal healing without resorption following avulsion and replantation:
1) Stage of root development (fully formed teeth had the lowest healing)
2) Length of the dry extra-alveolar storage period (the shorter the better)
3) Immediate replantation
4) Length of the wet extra-alveolar storage period

Question 16

Q242 : Describe the changes within the dental pulp following traumatic crown fractures?

Answer 16

Ozçelik et al (JOE -2000) showed that there are early and late responses of both the neural and vascular structure following trauma. They could be related to the type of external trauma (complicated or non-complicated crown fractures):
There was very slight increase in vascularization associated with a minimal cellular infiltration within the first few hours (1.5hrs following trauma).
In the early post-traumatic stages (17 hours), there was myelin degeneration surrounding the axons and edema
In the later stages (4 to 20 days), the tissues showed varying degrees of inflammation, and neuronal degeneration such as intramyelin edema, aberrant myelin synthesis, and axonal swelling.

Question 17

Q243 : When it is expected for an external root resorption to present following trauma?

Answer 17

If external root resorption after a traumatic dental injury will develop, it is usually seen within 1 year after the injury (Andreasen, Scan J of Dental Research - 1970).
Andreasen et al. (Dent Traumatol - 1995) showed that in cases of avulsion and replantation:
a) Surface resorption was generally diagnosed after 12 months.
b) Inflammatory resorption was usually observed after 1 month.
c) Replacement resorption (ankylosis) was usually observed after 1-2 months.

Question 18

Q244 : What are the different theories behind the development of invasive cervical root resorption?

Answer 18

There are two theories behind the triggering cause of invasive cervical root resorption:
According to Heithersay (Endodontic — 2004), A type of “benign proliferative fibrovascular or fibro-osseous disorder” in which microorganisms play no role and are absent or invade it only secondarily.
According to Fuss et al. (Dent Traumatol - 2003), microorganisms from the gingival sulcus provide the stimulus for continued resorption.

Question 19

Q245 : Explain how root resorption is triggered?

Answer 19

According to Hammarström & Lindskog (IEJ - 1985), the mineralized tissues of permanent teeth do not normally resorb. They are protected in the root canal by the pre-dentin and on the external root surface by pre-cementum.
If pre-dentin or pre-cementum becomes mineralized or mechanically injured, multinucleated cells will colonize the mineralized or denuded surfaces and root resorption will be triggered.

Question 20

Q246 : What is the most common type of resorption associated with avulsed teeth?
External inflammatory root resorption / Internal inflammatory root resorption /Cervical root resorption / Replacement resorption

Answer 20

Andreasen et al (Endod Dent traumatol - 1995) have shown that replacement resorption can occur in up to 64% of replanted teeth vs 30% would suffer from inflammatory root resorption.

Question 21

Q247 : In cases with horizontal root fracture, what are the factors that may result in pulp healing and hard tissue repair of the fracture?

Answer 21

According to Andreasen et al. (Dent Traumatol - 2004) (Part 1, Part 2), the below factors may contribute to pulpal healing and hard tissue repair following a horizontal root fracture injury:
1) Young age & Immature root formation
2) +Ve pulp sensibility at the time of injury
3) Optimal repositioning of the coronal fragment
4) No mobility of the coronal fragment

Question 22

Q248 : What is the incidence of internal root resorption?

Answer 22

Haapasalo & Endal (Endod topics - 2006) suggested that based on the limited data available, it can range between 0.01% to 1%

Question 23

Q249 : Which of the following is the most common complication following luxation injury?
Pulp necrosis / External inflammatory root resorption / Replacement root resorption / Cervical root resorption / Apical root resorption

Answer 23

Ferrazzini Pozzi & von Arx (Dental Traumatol - 2008) showed that the most frequent complication following luxation injury was pulp necrosis (24%).
Nikoui et al. (Dent Traumatol - 2003) also showed that 40% of laterally luxated teeth may suffer from pulp necrosis.
Andreasen & Vestergaard-Pedersen (Endod Dent Traumatol - 1985) reported that laterally luxated teeth with mature apices are significantly more likely to develop pulp necrosis than those with immature apices.
It should be noted that following trauma, teeth may not respond to vitality testing will the pulp sensibility tests. Teeth, however, could maintain vitality. Ahn et al. (JOE - 2018) showed that teeth may stay as long as one year before regaining vitality using cold testing. They also showed that ultrasound doppler flowmetry can also be a better way to determine pulp vitality in traumatized teeth (Ahn et al, JOE - 2018).

Question 24

Q250 : Which of the following would be the treatment of choice if a central incisor with an open apex is intruded 5mm into the socket?
No treatment / Orthodontic repositioning / Surgical repositioning / Intentional replantation

Answer 24

According to the 2012 International Association of Dental Traumatology (IADT) guidelines, no treatment should be performed allowing the tooth to passively erupt. The current guidelines did not change on that matter since 2012.
Cf tableau
Tsilingaridis et al. (Dent Traumatol - 2016) evaluated the survival of intruded permanent teeth according to the treatment provided, in a large number of patients. Very immature teeth, teeth diagnosed with mild intrusion, and teeth awaiting re-eruption had significantly fewer complications.

Question 25

Q251 : How is root resorption regulated?
RANK/RANK-L/OPG System

Question : What is the cellular mechanism of root resorption?

Answer 25

The process of root resorption is similar to bone resorption
- In the presence of inflammation/infection, there is excessive production of inflammatory cytokines (IL1, TNF alpha etc) by inflammatory cells
- This results in excessive production of RANK-L and low production of OPG by osteoblast/cementoblast (depending on the type of tissue bone/cementum) present at the area.
RANK-L binds to RANK on the immature clastic cells. This results in cell fusion, formation and maturation of multi-nucleated clastic cells. (osteoclast/cementoclast)
RANK-L continues to bind to RANK on the mature clastic cells. It’s essential for clastic cell function and survival.
- Clastic cells attach themselves to the bone surface with the help of some proteins (Osteopontin, Fibronectin, Vitronectin)
- They form a Ruffled border where a proton pump starts (proton pump is the pumping of hydrogen ions to make the area more acidic to initiate resorption). This results in: dissolution of the hydroxyapatite (inorganic structure)
- Degradation of the organic matrix then occurs by the secretion of the following enzymes
a) Collagenases (neutral pH)
b) Matrix metalloproteinases (neutral pH)
c) Cysteine proteinases (acidic pH)