What is Perforation ?

According to glossary of endodontic terms (by AAE), perforation is defined as “the mechanical or pathological communication between root canal system and the external tooth surface.”  

It can be classified as cervical, mid-root, or apical levels depending upon site of the perforation.

Cervical canal perforation occurs mainly during location of canal orifice and flaring of the coronal third of the root canal 

Mid-root perforation occurs due to over instrumentation and over-preparation of thin wall of root or concave side of the curved canals 

Apical root perforation occurs when instrument goes beyond the confines of the root canal and by overuse of chelating agents along with straight and stiffer large-sized instruments to negotiate ledge, canal blockage, or zipping, etc 

Reasons for iatrogenic cervical perforations:

• Failure to interpret the pre-operative radiograph and anatomy of teeth and internal pulp space anatomy accurately 
• Calcifications in pulp chamber 
• Angulation of teeth 
• Crown and root anatomy variations 
• Lack of clinical skill 

Occurrence of a perforation can be recognized by: 

• Most pathgnomonic feature is appearance of blood from the pulp chamber or canal orifices 
• Placing an instrument into the site and taking a radiograph 
• Using paper point and observing for blood stain 
• Patients complains of pain on placing instrument 

Most common anatomic site in the tooth where perforation occurs:

• Maxillary incissors – facial aspect 
• Mandibular incissors – facial, mesial or distal aspect 
• Maxillary premolars – mesial or distal aspects 
• Mandibular premolars – facial aspect 
• Mandibular molars – lingual aspect 
• Maxillary and mandibular molars with receeded pulp chamber – furcation area  

Factors Affecting Prognosis of Perforation Repair:

• Visibility and accessibility – Better the access and visibility to the site of perforation, better is the clinician’s ability to repair it 
• Time – Faster the perforation repair better is the prognosis 
• Esthetics – It is to be considered when the perforation repair is in case of anterior or premolar teeth 
• Associated periodontal condition 
• Location - If perforation is located at alveolar crest or coronal to it, prognosis is poor because of epithelial migration and periodontal pocket formation. Perforation in the furcation area has a poor prognosis. Perforation occurring in mid-root and apical part of root does not have communication with oral cavity and thus has good prognosis.
• Size - A smaller perforation has less tissue destruction and inflammation, thus having better prognosis than larger sized perforation 

Various Materials Used For Perforation Repair:

• MTA
• Biodentine
• Endosequence
• New endodontic cement (NEC) also called as Calcium Enriched Mixture (CEM)

"Prevention of perforation is by adhering to the basic principles of access cavity opening and using files in correct manner and order"

 Article by Dr. Siri P. B.