• Root resorption is a condition associated with either a physiologic or a
pathologic process resulting in a loss of dentin, cementum and/or bone
• It may be initiated in the periodontium and affect initially the external
surfaces of the tooth (external resorption) or it may start within the pulp
space affecting primarily the internal dentin surfaces (internal
• With the exception of minor, transient surface resorption, loss of
tooth structure is irreversible.
• Treatment, when successful, can only arrest the process and when
less successful, slow down resorption.
• If not diagnosed and treated, that can lead to tooth extraction.
• The etiology of root resorption requires two phases: Injury and Stimulation
The injury is similar to several types of root resorption
• Injury is related to the non-mineralized tissues covering the external surface of
the root, the precementum, or internal surface of the root canal, the
A clinical-related classification of root resorption that will assist in diagnosis
and treatment of the pathological process.
Pulpal infection root resorption
Periodontal infection root resorption
Orthodontic pressure root resorption
Impacted tooth or tumor pressure root resorption
Ankylotic root resorption
Internal resorption is relatively rare in occurrence
It is caused by trauma
Transient variety involves only loss of odontoblasts and predentin and
therefore is shallow. It is self limiting and is repaired presumably with new
Progressive internal resorption continues from the point where dentin is
exposed after the loss of odontoblasts and predentin.
The stimulus for resorption is often provided by infected, necrotic pulp
tissue coronal to the resorptive lesion.
The resorptive process requires vital tissue, hence although clinically the
pulp space coronal to the resorptive defect may have necrotic tissue, the
rest, including the area of resorption , may contain vital tissue
• Resorption usually occurs till the necrotic process overtakes the vital tissue
in the remainder of the pulp space, thus depriving the tissue of needed
blood supply, at which time the internal resorptive process ceases.
Recognition is both clinically as well as by radiographic means.
Clinical finding – Pink spot. If the resorption involves the crown , a pink area may
show through the enamel
No specific symptoms such as pain
OUTLINE OF LESION: Sharply outlined
appearance (than in external resorption).
OUTLINE OF ROOT CANAL: Outline of the
root canal is lost.
CHANGE IN ANGULATION: Radiographs
taken from different angles tend to show
the resorptive lesion in the central
EXTERNAL ROOT RESORPTION:
It is associated with trauma to teeth in which the injury damages cementum
The traumatic event maybe avulsion, luxation, orthodontic forces or periodontal
Maybe transient or progressive.
Surface resorption is not detected radiographically and can be observed only
Inflammatory resorption: can be of pulpal or periodontal origin
Four factors that contribute to the development of IERR.
Inury to the PDL: Most frequently this occurs when the ligament is torn,
such as in avulsions and luxations
Initiation of surface resorption: damage to the root surface leads to the
surface resorption of cementum. For the process to continue, the surface
resorption must expose the subjacent dentinal tubules.
Communication with the necrotic pulp tissue or an inflammatory zone
favouring bacteria: if the traumatic event has resulted in significant
reduction or complete destruction of pulpal blood flow → necrosis →
Patency of dentinal tubules: larger the diameter of the tubules the more
rapid is the resorption
History of trauma: maybe recent or may have been several years earlier.
The onset and pace of resorption depends on the pulpal condition and the
patency of the communicating dentinal tubules.
Clinical findings: based on the results of examination procedures such as
percussion, palpation, mobility evaluation and periodontal probing.. in most
cases the pulp is either necrotic or irreversibly involved. Sensitivity to
percussion may be due to the periradicular inflammation; surrounding
alveolar bone maybe sensitive to palpation because of osteitis
Radiographic evidence will demonstrate loss of both tooth structure and
adjacent alveolar bone.
Not so sharply outlined appearance (than in internal resorption).
Outline of the root canal is seen.
Radiographs taken from different angles tend to move the resorptive lesion
Removal or reduction of the source of infection
It has been recommended to include a calcium hydroxide phase to the root
canal treatment to enhance the outcome
Calcium hydroxide for 6-24 months is the intracanal medicament of
choice for the treatment of ERR
has strong anti-bacterial effect
also increases the pH of dentin →inhibits the activity of osteoclastic
acid hydrolases in the periodontal tissues and activates the alkaline
Replacement resorption / Ankylotic root resorption :
When tooth structure is replaced with bone that fuses with dentin, it is termed
It occurs frequently as a result of complications following avulsions in which the
PDL dries and loses its vitality
Ankylosis may be transient or progressive.
Transient type :
Less than 20% of the root surface becomes ankylosed. In such cases reversal
may occur, resulting in re-establishment of a PDL connection.
Progressive type :
The tooth structure is gradually resorbed and replaced with bone.
Histologically there is a direct fusion between the bone and dentin.
Clinically several problems are noted :
Incomplete alveolar process development
( if the patient is young)
Prevention of, normal mesial drift.
Clinical -: Lack of mobility and high pitched metallic sound when percussed.In
such cases more than 20% of bone has been ankylosed.
If less than 20%, then it cannot be reliably detected clinically.
Radiographic: loss of PDL space with replacement by bone in association with an
uneven contour of the root
There is currently no treatment for replacement resorption.
Limiting the damage to the PDL is the most important factor in avoiding
the development of ankylosis.
It maybe possible to slow down the resorptive process by treating the root
surface with a fluoride and / tetracycline solution prior to replantation
Functional stimulation and flexible rather than rigid splinting of the tooth
during the healing phase has been shown to reduce the area of ankylosis
A type of resorption that involves the cervical area of the tooth . commonly
called Invasive cervical resorption.
“ Late external resorption” : as this resorption may not become clinically evident
until years after the original injury. Other terminologies used are
Peripheral cervical resorption
Cervical external resorption
Extra canal invasive resorption
Supraosseous Extra canal invasive resorption
Invasive cervical resorption is initiated from the cells in the periodontal
ligament and is characterized by the ingrowth into the cervical area of the
tooth by fibro-vascular tissue which slowly resorbs enamel, cementum and
A likely pre-requisite is the deficiency in the normally protective
Cementum-cementoid layer / Precementum, either due to congenital
absence or due to damage caused by physical or chemical trauma
Initially the resorptive tissue is devoid of inflammatory cells indicating a
non-bacterial etiology. Secondary bacterial invasion at a later stage will
elicit a normal inflammatory response in the associated periodontal or
The pulp is usually protected until late in the process by a thin layer of
dentine and Predentin
Causes: trauma, orthodontic tooth
movement, dento alveolar surgery,
secondary bone grafting of alveolar
clefts, Periodontal treatment,
intracoronal bleaching of teeth, and
in some cases idiopathic
Clinically a pink spot maybe observed cervically .
The resorptive lacunae can be probed through the gingival sulcus and maybe
observed to extend coronally under the enamel.
The exposed dentin is hard(unlike carious) and the lacunae contains vascular
Class 1: a small invasive resorptive lesion near the cervical area with shallow
penetration into dentin
Class2: a well defined lesion that has penetrated close to the coronal pulp
chamber but shows little or no extension into radicular dentin
Class 3: a deeper invasion into coronal dentin and also extending at least to
the coronal 3rd of the root
Class 4: a large lesion that has extended beyond the coronal third of the root
canal, and may involve almost half the root
Lesion may have smooth or a rough outline. Because the adjacent
bone is often involved the resorption may often give appearance of
an infrabony pocket.
The root canal outline is intact.
The appearance varies from an irregular moth-eaten appearance to a
more regular radiolucency which may resemble caries
Successful treatment relies upon the complete removal or inactivation of the
resorptive tissue. This is difficult to obtain in more advanced lesions.
In most cases, surgery is necessary to gain access to the resorptive
defect and often may cause loss of bone and periodontal attachment.
Topical application of a 90% aqueous solution of trichloracetic acid, curettage
and sealing of the defect has proved successful in most cases.
Large defects associated with advanced stages of this condition have a poor
Replacement resorption or ankylosis occurs following extensive necrosis of
the periodontal ligament with formation of bone onto a denuded area of the
Various pressures can lead to resorption. Some examples include
orthodontic forces, excessive occlusal forces, pressure from impacted or
supernumerary teeth and pressure from tumors and cysts..
Two factors are associated with pressure resorption:
pulp is usually not involved, at least not initially
resorption tends to be arrested when the cause is removed.
When no etiologic factor can be identified, root resorption has been classified as