Perforation in access surgery. Causes, detection of perforation signs, and how to prevent this very common accident in endodontic practice.
In: Ricardo Machado. Biological and Technical Principles. Ed. Gen, 2022:
Coronal perforation
Accidental communication between the pulp chamber and the oral medium and/or periradicular tissues.
Main causes
Inobservance of the degree of inclination of the tooth and/or institution of inadequate trepanation direction, use of drills of a diameter incompatible with the coronary volume, inexperience and/or lack of skill of the operator.
Preventive measures
The prevention of coronary perforations is based, above all, on the institution of a correct planning based on a careful clinical-radiographic examination, and on knowledge about dental anatomy and morphology.
When in doubt, radiographs with different horizontal angulations should be taken. For even more critical cases, cone beam computed tomography (CBCT) provides three-dimensional visualization of the teeth without overlapping anatomical structures and greater detail richness.
After access to the pulp chamber with a ball burs, inactive-tipped burs such as Endo-Z, 3082 and 3083 are recommended to determine the contour shape. The preparation of the canal entrance should be carried out with a Largo bur or specific instruments (hole openers, Orifice Shapers etc.).
For teeth with pulp chamber and/or atrophic canals, the coronary opening can be enlarged to obtain better luminosity and visualization.9 In these cases, the use of a magnifying glass or operating microscope associated with ultrasonic inserts and/or long-stemmed burs is strongly recommended, as well as the application of dyes to differentiate between dentin types, in order to perform safer grinding. Easy access to calcified canals has been achieved with "Guided Endodontics". For more details, we recommend reading Chapter 35, CAD/CAM Guided Endodontics - Endoguide 3D.
Diagnosis
Coronary perforations can be identified by characteristic signs, such as pain when the area is contacted (even with the patient under anesthesia), bleeding, burning sensation or bad taste reported by the patient during and/or after irrigation with sodium hypochlorite, and unstable or apparently incorrect readings provided by the electronic foraminal locator.
In the presence of an intraosseous subgingival coronal perforation, when there is no contamination, the sealing/filling must be immediate. Initially, the area is chemically and mechanically cleaned with low concentration sodium hypochlorite (0.5%) and curettes or ultrasonic tips, respectively. After drying with absorbent paper cones, the sealing material is applied and compacted with resin spatulas and/or tampers compatible with the size of the perforation.
Several materials have been used for sealing intraosseous subgingival coronal perforations, such as silver amalgam, zinc oxide and eugenol-based cements, calcium hydroxide pastes, glass ionomer cement, composite resin and SuperEBA-all of which have significant clinical limitations.16,17 Mineral trioxide aggregate (MTA), developed in the 1990s, and other more recent bioceramic materials have substantially improved the prognosis of teeth affected by intraosseous and root subgingival coronal perforations (see below).18 This is mainly a result of their favorable characteristics, such as biocompatibility, sealability, insolubility in tissue fluids, and long-term dimensional stability. The newer ones - Biodentine,26 MTA Repair HP,27 Bio-C Repair,28 NeoMTA29 and EndoSequence Root Repair Material30 - also have advantages such as shorter setting time and easier handling compared to MTA.
Perforation in access surgery
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