Strategies for Iatrogenic Perforations
Iatrogenic perforations are the most frequent type, and several factors must be taken into consideration in their management.
The sooner the perforation is sealed, the better. Many studies have demonstrated that the best time to seal the perforation is at the time it is produced. Perforations close to the bone crest, that initially only affect bone, quickly get contaminated from the oral cavity along the sulcus to involve the periodontium
. The decision whether to fill the canals first or to seal the perforation first is determined on a case-by-case basis.
In the past, the "internal matrix" concept was used fairly successfully. Today, it is no longer necessary to use the internal matrix; instead, MTA cement can be put directly into the perforation site even if it is extrused.
Owing to its high biocompatibility, human periodontal ligament fibroblasts and cementoblasts can attach to MTA cement in 4 hours and spread out in 24 hours, and alveolar bone cells differentiate into osteoblasts, proliferate and deposit osteoid matrix like an overlay in 7 days. MTA has proven to be the best material fo obturation.
If the access is wide enough, MTA can be used wet, like a drop with a fine instrument. It can be vibrated directly with the instrument it self. Then it is condensed and dried at the same time with a paper point. If the canal is too narrow, the use of a syringe is suggested, and the MTA used is drier and vibrated indirectly by ultrasound.
SuperEBA is a reinforced and more biocompatible IRM cement. Its setting time is shorter, but it is difficult to manage and is sensitive to humidity and temperature.
Although IRM has been largely superseded by superEBA cement, IRM is still used in large perforations, because it is more easily managed than MTA and it has a longer setting time than superEBA.
Size and Shape
Small perforations are easiest to seal. Large perforations can cause the problem of incomplete sealing, allowing continuous bacterial irritation of the perforation area. The larger and longer the perforation, the worse is the scenario. A strip perforation can run from the furca floor down along the root almost affecting all the root length.
Round perforations are easier to seal than oval or teardrop types, but round perforations are produced only at the furca floor . A round furcal perforation is the easiest to seal because of its shape and good access; but if it is not treated urgently it rapidly produces a periodontal pocket that can darken the prognosis.
Oval perforations are more difficult to seal because of their shape. They can vary from small to very large.
Location is the most important factor in relation to the decisionmaking process and treatment prognosis. Perforations can be suprabony (coronal) or infrabony (crestal, furcal, radicular). Generally speaking, suprabony perforations do not affect supporting bone and can be sealed non-surgically with composite.
"Crestal perforation" is a suggested term to use when an infrabony perforation is localized close to the bone crest. In this situation, a rapid inflammation of the dentogingival junction produces a sulcus epithelium proliferation.
Permanent contamination of the periodontal pocket makes aseptic sealing of the perforation difficult. Its treatment could be surgical (crown lengthening) or non-surgical: orthodontic (forced extrusion) with the aim of relocating the lower border of the perforation at a coronal level to the dentogingival junction.
Furcal perforations are usually treated non-surgically. They are the easiest perforations to seal because of good access and their round shape. If the position of the furca is superficial, the perforation is considered in a crestal position and its treatment is urgent because it can produce a periodontal pocket. If the furca is deep, then the perforation is considered infrabony and it rarely involves the periodontium.
Radicular perforations are treated non-surgically. The further away from the bone crest (although they have a more difficult access), the better is the prognosis because a periodontal pocket is rare20 30. Most of them are strip perforations and they are the perforations with the most difficult treatment because of their shape, size and location. They can be as long as the affected root. They can begin in the furca roof and spread down to the apical zone, so they can be crestal in their initial part and totally infrabony in their final part.
Radicular perforations are first tackled non-surgically; if that fails then surgical access is chosen. If they drain through the furca, fast treatment is crucial in order to operate when the loss in the mesial and distal bone height crest has not been produced yet, and in this way to close the surgical access to the furca with a favorable marginal osseous height and make the total area regeneration easier.
When a radicular perforation in a multirooted tooth does not allow surgical access, or the perforation was produced by a non-surgical removable post, or it is impossible to remove it surgically, then either hemisectioning, root amputation, intentional replantation, or extraction will be the chosen treatment, as discussed later in this chapter.
The further the perforation is from the bone crest, if it is small and accessible, the better the prognosis will be. The problem is that apical perforations are associated with ledges, blocks at the curved part of the canal, so access is difficult and proper sealing of both the canal and the perforation is required to get success.