ENDO root resorption

Question 1

what is the definition of root resorption?

Answer 1

a physiological or pathological event mainly occurring due to the action of activated clast cells

Question 2

what is root resorption characterised by?

Answer 2

the transitory or progressive loss of cementum or cementum/ dentine

Question 3

what is the onset of root resorption associated with?

Answer 3

significant necrosis of cementoblasts and/or injury to the PDL

Question 4

what are the 2 phases required to cause root resorption?

Answer 4

injury and stimulation

Question 5

what types of injury cause root resorption?

Answer 5

mechanical
infection of root canal or PDL
chemical

Question 6

what types of mechanical injury causes root resorption?

Answer 6

trauma
surgical procedures
excessive pressure (impacted teeth, cyst tumours, ortho tx)

Question 7

what type of chemical injury causes root resorption?

Answer 7

bleaching agents (30% hydrogen peroxide)

Question 8

what type of stimulation causes root resorption?

Answer 8

infection
pressure
transient resorption (without a constant stimulus the process if self limiting)

Question 9

lost systemic and endocrine disease which may cause root resorption?

Answer 9

hypo and hyperthyroidism
calcinosis
gauchers syndrome
turner syndrome
pagets disease
herpes zoster

Question 10

what type of cells colonise damaged surfaces and initiate the resorptive process?

Answer 10

odontoclasts/ osteoclasts

Question 11

what are howships lacunae?

Answer 11

depressions of odontoclasts/ osetoclasts

Question 12

what cells regulate the physiological and pathological resorption of mineralised tissue?

Answer 12

receptor-ligand system RNAKL/RANK/OPG - part of the TNF family

Question 13

what cells carry the RANK receptor?

Answer 13

osteoclast precursor cells and dendritic cells

Question 14

what induces the fusion of osteoclast precursor cells into multinucleated cells?

Answer 14

binding of RANKL to RANK

Question 15

what is the most common cause of resorption?

Answer 15

pulp infection

Question 16

what are causes of resorption, based on stimulation factors?

Answer 16

pulp infection
PDL infection
ortho pressure
ankyloses
tumour
impacted pressure

Question 17

what does EIR affect?

Answer 17

the external root surface

Question 18

what usually causes EIR?

Answer 18

trauma - intrusion, lateral luxation and avulsion

Question 19

how is EIR diagnosed?

Answer 19

radiographic and CBCT interpretation

Question 20

how is EIR treated?

Answer 20

removal of necrotic pulp as soon as signs of EIR
calcium hydroxide as an interappointment dressing
most cases, resorption too advanced to treat

Question 21

where do you find invasive cervical resorption?

Answer 21

on external root surface but can invade root dentine in any direction
develops immediately apical to epithelial attachment in cervical region

Question 22

what causes ICR?

Answer 22

loss of protective non-mineralised layer at the CEJ - developmental, physical/ chemical trauma
microbial stimulation from gingival sulcus

predisposing factors: ortho, trauma, surgery, intracoronal bleaching

Question 23

how is ICR differentiated from IRR?

Answer 23

ICR is a periodontally derived form of ERR

Question 24

what are the clinical features of ICR?

Answer 24

asymptomatic
tooth may look pink
positive sensibility test
tooth will be vital as pulp is protected until late in the process by a layer of dentine and predentine
eventually, the lesion will perforate the canal wall resulting in canal infection and necrosis

Question 25

what are the clinical classifications of ICR?

Answer 25

Heithersay 1999 class I - small with shallow penetration class II - close to coronal pulp, no radicular extension class III - deeper but not beyond coronal third class IV - extensive beyond coronal third

Question 26

what are the radiographic features of ICR?

Answer 26

radiolucent area which can be confused with IRR *use parallax and CBCT for further info

Question 27

what is the treatment for ICR?

Answer 27

remove granulation tissue from defect with 90% trichloracetic acid restore with GI, composite or biodentine RCT if communication with pulp canal

Question 28

where does IRR originate?

Answer 28

in and affects the root canal wall follows damage to odontoblastic layer and predentine

Question 29

what is the aetiology of IRR?

Answer 29

still unknown - mostly a result of trauma

Question 30

what is required for IRR to continue?

Answer 30

pulp tissue apical to the lesion must have a viable blood supply eventually the pulp will become necrotic and resorption will stop

Question 31

clinical appearance of IRR?

Answer 31

extensive resorption can result in pink discolouration of the crown (may be confused with ICR)

Question 32

radiographic features of IRR?

Answer 32

oval, round lesions any site along root canal usually symmetrical the outline of the root canal cannot be traced as IRR cavity is continuous with normal root canal walls

Question 33

treatment for IRR?

Answer 33

RCT if tooth can be saved lesion difficult to clean (bleeding) and obturate (shape) so can use thermoplastic techniques

Question 34

what happens if IRR left untreated?

Answer 34

perforation and clast cells can obtain nutrients from surrounding tissues

Question 35

what is orthodontic pressure root resorption?

Answer 35

apical root resorption can occur as a result of injury originating from the pressure applied to the roots during tooth movement

Question 36

are teeth symptomatic in the case of ortho pressure root resorption?

Answer 36

teeth are asymptomatic and pulp remains vital unless pressure is such that it disturbs the apical blood supply

Question 37

radiographic features of ortho pressure root resorption?

Answer 37

shortened roots with no signs of radiolucency in the bone

Question 38

what teeth does impacted tooth pressure resorption affect?

Answer 38

maxillary canines and mandibular third molars

Question 39

what type of tumours may cause pressure resorption?

Answer 39

slow growing cysts ameloblastomas giant cell tumours fiber-osseous lesions

Question 40

what is ankylotic root resorption referred to as?

Answer 40

replacement resorption

Question 41

what type of injuries may cause ankylotic root resorption ?

Answer 41

in severe traumatic injuries: intrusive luxation, avulsion with delayed reimplantation

Question 42

how is ankylotic resorption caused?

Answer 42

injury to the root canal is so large that healing with cementum is not possible and the bone comes into contact with the root surface. osteoclasts are in direct contact with the mineralised dentine and therefore resorption can occur without further stimulation and bone is laid down instead

Question 43

clinical findings for ankylotic root resorption?

Answer 43

teeth lack physiological mobility and sound metallic to percussion, sometimes in infra occlusion

Question 44

radiographic findings for ankylotic root resorption?

Answer 44

bone fills the resorption lacuna and there is no radiolucency

Question 45

treatment for ankylotic root resorption?

Answer 45

no stimulation factor to remove and no predictable tx prevention - minimise damage to PDL functional splint can be placed for 7-10 days and RCT to prevent pulpal infection and resorption