Pulp canal calcification is 1 of the possible outcomes after certain types of dental trauma. This can make endodontic treatment more challenging should it become necessary. Because of the increased degree of difficulty, sometimes procedural incidents do occur during root canal treatment. This case report demonstrates an unusual clinical presentation of a root perforation and missed canal, which had undergone calcification as a result of trauma some years earlier. A contemporary approach to treatment involved a combination of treating the biological complication of the calcified canal combined with surgical repair of the iatrogenic complication of a perforation using modern imaging techniques and materials.
Pulp canal calcification is 1 possible complication after dental trauma and can make endodontic treatment more complex. Perforation is 1 possible complication; however, this can often be repaired successfully using modern techniques and materials.
Narrowing of the root canal system is 1 possible outcome after dental trauma and can lead to pulp canal calcification (PCC), also known as pulp canal obliteration , , calcific metamorphosis , and dystrophic calcification . PCC is related to the age of the patient at the time of trauma and generally affects teeth with incomplete root formation at the time of the injury, although it is not exclusive to immature teeth , . It is also more common after injuries that result in displacement of the tooth such as luxation injuries . The reported prevalence of PCC after concussion injuries to teeth with immature roots is 3% and 7% in teeth with fully formed roots. The prevalence after subluxation injuries is slightly higher, at 11% and 8%, respectively, for immature and fully formed roots .
The term PCC is essentially a description of the radiographic appearance of the root canal and can be described as partial or complete depending on the radiographic appearance. In reality, there is almost always a canal remaining, albeit smaller in diameter, with pulp tissue inside; however, it is so narrow that it cannot be detected on plane radiographs .
Another common feature of PCC is that the coronal tooth structure can become discolored because of the deposition of dentin, and this often results in a crown with a dull, yellow hue and, less commonly, a gray hue. This discoloration is thought to be due to altered light transmission through the tooth caused by a gradual opacification of the tooth as dentin is deposited and becomes progressively thicker , .
Narrowing of the root canal after traumatic injuries is a result of pulpal healing caused by revascularization and reinnervation, which is associated with rapid dentin deposition. It is regarded as a form of repair and not a result of a diseased pulp . Although the canal may be narrower, the pulp inside the canal is, from a histologic point of view, essentially normal. Apart from Lundberg and Cvek's light microscopy study in 1980 , there is very little in the dental literature concerning the histopathologic appearance of pulp tissue after PCC. Lundberg and Cvek examined the pulps of 20 maxillary permanent incisors with PCC after trauma and reported moderate inflammation in only 1 pulp, and none of the pulp specimens showed any evidence of bacterial contamination. The specimens sometimes had a significant reduction in the number of cells and increased collagen, whereas others were rich in cells with a slight increase in collagen. The structure and appearance of the collagen and cells were normal.
It is believed that differences in the chronology of neural and vascular repair may cause a loss of control of sympathetic nerves involved in regulating the secretory activity of odontoblasts. If this regulatory control is not regained, there will be a continued deposition of dentin until complete pulp canal calcification has occurred .
Narrowing of the canal means that endodontic treatment, should it become necessary, is more challenging from a technical point of view. This means that procedural errors such as failure to locate the canal, removal of excessive tooth structure in searching for the canal, or perforation of the tooth are more likely , . If a perforation does occur, this can be managed by either an internal or surgical approach to repair the defect; however, the tooth always remains compromised to some extent, and future problems are more likely .
With the advent of modern imaging technologies such as cone-beam computed tomographic (CBCT) imaging, the problem of inability to visualize the canal on plane radiographs can be overcome in many cases . This may assist the clinician with treatment planning as well as assessing case difficulty and the location of the canal.
A 24-year-old man was referred for endodontic assessment of his upper right central incisor (tooth #8), which had been endodontically treated by his general dentist 7 months before. The patient's medical history was noncontributory. His dental history included orthodontic treatment in his early teens and being hit in the mouth by a glass bottle when he was 18 years of age. He was drinking from the bottle when it was knocked forcefully into his mouth by another person's elbow. After being hit with the bottle, the patient recalls that the tooth was slightly loose and somewhat tender for a week or so, after which all symptoms resolved and the tooth returned to normal mobility and function. No dental treatment was sought by the patient at that time. Several years after this incident, the patient's mother noticed the tooth had become slightly yellow and encouraged the patient to see his dentist for advice. The dentist recommended root canal treatment based on the history, calcified canal, and color change.
The endodontic treatment was performed over 2 visits, and immediately after the root filling appointment, the patient noticed a swelling in the gingival sulcus directly above tooth #8. At no stage was the swelling painful or otherwise symptomatic, but the patient was concerned that it was persisting. The referral from the dentist requested possible endodontic retreatment because it was thought that the original treatment may have become infected.
On examination, the patient had good oral hygiene, and none of the teeth were tender to percussion or palpation. The periodontal probing depths were within normal limits, and all of the surrounding teeth were positive to CO 2 pulp sensibility testing. Tooth #8 had a very subtle yellow hue compared with the adjacent teeth, although this was not bothersome for the patient. There was an asymptomatic, firm, 4-mm diameter swelling over the apex of tooth #8 with no suppuration or obvious inflammation ( Fig. 1 A ). A periapical radiograph demonstrated an undercompacted root filling, which was somewhat short of the ideal length; however, there was no evidence of apical pathosis and no obvious cause for the swelling ( Fig. 1 B ).
A small field of view CBCT scan was ordered to assist with the diagnosis (Morita Accuitomo; J Morita Corporation, Kyoto, Japan). This revealed a moderately calcified pulp canal, which appeared not to have been accessed during the original endodontic procedure. There was also a midroot perforation on the labial aspect of the tooth, approximately 5 mm superior to the alveolar crest ( Fig. 2 ). Root filling material was noted to have extruded through a perforation on the labial aspect of the tooth root and the labial cortex of the alveolar bone, extending into the adjacent soft tissues. After viewing the CBCT scan, the pulp sensibility testing was repeated. The tooth gave a negative response to CO 2 but was positive to an electric pulp test (Analytic Technology Pulp Tester; Analytic Technology, Redmond, WA), equivalent to the unaffected surrounding teeth.
At this point, the tests indicated that the pulp inside the tooth was clinically and radiographically normal other than the narrowing of the canal caused by calcification, which was likely to have been caused by the trauma several years earlier. The swelling was caused by the root filling material embedded in the soft tissues rather than a result of infection or other pathosis.
The treatment options were discussed with the patient, and he consented to proceed with retrieval of the perforating root filling because of the irritation it was causing and the potential for future complications. It was hoped that the root filling would be able to be retrieved via a nonsurgical, internal approach followed by repair of the perforation, perhaps avoiding the need for root canal treatment given the fact that the clinical and radiographic tests indicated a normal although somewhat calcified pulp. The patient was also informed that endodontic treatment and/or surgical repair of the perforation site might be required.
At the first treatment appointment, local anesthetic was administered via buccal infiltration injection with 1 mL articaine 4% with 1:100,000 adrenaline (Septanest 1:100,000; Septodont, Saint-Maur-des-Fossés, France). Single-tooth dental dam isolation was applied, access was gained, and the perforation site was identified on the labial side of the tooth, approximately 4–5 mm above the gingival margin. The perforation site was approximately 2–3 mm in diameter. The calcified canal could also be seen, and a sharp DG16 endodontic explorer (Kerr Endodontics, Orange, CA) exposed the pulp when pressed onto the calcified tissue. At this point, the decision was made to initiate root canal treatment. The working length was determined using an apex locator (Root ZX Mini, J Morita Corporation) and confirmed radiographically. The root canal was prepared using rotary nickel-titanium instruments. Initial canal negotiation and glide path creation were achieved with a 13/02 instrument (PathFile; Dentsply Sirona, Ballaigues, Switzerland), and the canal was then prepared to size 35/04 at the apex (Vortex, Dentsply Sirona). The irrigant used during canal preparation was 10 mL, 4% sodium hypochlorite (Endosure Hypochlor 4% Forte; DentaLife, Victoria, Australia). The canal was then dressed with calcium hydroxide paste (Pulpdent Paste; Pulpdent Corporation, Watertown, MA) and the access cavity closed with a double seal of glass ionomer cement (Fuji IX GP Fast; GC Corporation, Tokyo, Japan) over Cavit W (3M Espe, Seefeld, Germany).
The perforating root filling was found to be a carrier-based material with a solid gutta-percha core as the carrier. The brittle nature of the gutta-percha carrier meant that it was not possible to remove the perforating root filling. Consequently, a surgical approach was required to remove the root filling and repair the perforation.
At the second treatment appointment, the area was anesthetized with 1 mL articaine 4% with 1:100,000 adrenaline via buccal infiltration, and a dental dam was applied. The canal was flushed with 5 mL 15% EDTA-C (Endosure EDTA-C, Dentalife), and 5 mL 4% sodium hypochlorite was then used as the final irrigant. The canal was subsequently dried with paper points and filled with gutta-percha and AH Plus sealer (Dentsply Sirona). The access cavity was restored with a dual-cure resin composite (LuxaCore Z; DMG, Hamburg, Germany) over a base of GIC (Fuji VII, GC Corporation).
One week later, the surgical procedure was performed. Local anesthetic consisted of buccal and palatal infiltration injections using 4 mL articaine 4% with 1:100,000 adrenaline. A full-thickness, trapezoidal flap was raised incorporating an intrasulcular incision with releasing incisions at the distal aspects of teeth #7 and #9 ( Fig. 3 A ). The perforating root filling was removed from the gingival tissues with some difficulty because it had become encapsulated in tough fibrous tissue and had to be carefully dissected out of the soft tissue of the flap using a sharp Half Hollenback carver (Hu-Friedy Mfg Co, Chicago, IL). The remaining root filling was removed from the perforation site using microsurgical ultrasonic tips (ProUltra, Dentsply Sirona). The perforation was then repaired with mineral trioxide aggregate (MTA) (ProRoot MTA White, Dentsply Sirona) ( Fig. 3 B and C ). The flap was then secured with 4/0 plain surgical gut sutures (Dynek Pty Ltd, Adelaide, Australia).
At review 2 weeks later, the patient was feeling comfortable, and the area was seen to be healing well. At the 2-year review, the patient reported that the area had been free of symptoms since the completion of treatment. Clinical and radiographic examination showed the area to be healthy and free of any ill effects from the event ( Fig. 4 A and B ).
Pulp canal calcification is 1 possible outcome after dental trauma . This in turn may cause the tooth to become discolored, and this, as demonstrated in the current case, may lead to the tooth being endodontically treated. Appropriate diagnostic tests must be performed before embarking on endodontic treatment to establish the possible presence of pulp necrosis in cases of PCC. Pulp sensibility testing is still appropriate; however, the use of thermal tests may be more likely to result in false-negative results in cases of PCC because of the increased thickness of the dentin wall. Electric pulp testing is more reliable in such cases . A negative pulp sensibility test in the absence of any corroborating signs or symptoms of infection or inflammation does not necessarily mean that endodontic treatment is required. The development of apical periodontitis after PCC is not inevitable, so endodontic treatment should be avoided unless signs and symptoms of infection are present. There are few long-term studies, but these report a range of 1%–27.2% for the development of apical periodontitis after PCC , , , .
When considering endodontic therapy for teeth with PCC, clinicians must be aware that treatment can be extremely challenging from a technical point of view, and perforation is 1 of the possible complications when searching for a calcified canal. Management of a perforation can be difficult and, as demonstrated in the current case, sometimes requires a surgical approach to successfully repair the area.
The prognosis after perforation repair is dependent on 3 main factors: size, position, and age of the perforation , . In the case described, the perforation was at about the midroot level, was of small to medium size, and there was no communication with the oral environment; thus, there was limited opportunity for infection of the site. The patient also had good oral hygiene, and all of these factors mean the prognosis for this case is excellent.
The current literature also favors the use of bioactive endodontic cements such as MTA for the repair of perforations to maximize the chances of long-term success . One of the drawbacks of MTA, which was first developed in the 1990s, is that it is known to cause discoloration of the tooth structure over time , . A number of new bioactive endodontic cements have been introduced to the market in recent years. These have also shown promising results without the complication of tooth discoloration , although long-term studies compared with MTA are lacking.
Conclusion and Clinical Implications
The present case serves as a reminder that PCC significantly raises the degree of difficulty of endodontic treatment should it become necessary. PCC results in abnormal calcification of the root canal, whereas the pulp tissue itself remains essentially normal, so pulp sensibility tests are mandatory in helping assess the health of the pulp tissue. The use of a high-resolution, small field of view CBCT scan should be considered when planning for endodontic treatment in such cases, first to help assess the difficulty of the case and second as an aid to assist in the location of the canal. Perforation is 1 possible complication, which on rare occasions may go unrecognized. Treated appropriately using contemporary techniques and materials perforations can be managed with a high degree of predictability.