PMC7006556_01
(a) Preoperative periapical radiograph. (b) Intraoperative radiograph of the working length determination. (c) Immediate postoperative radiograph. (d) Radiograph after fiber post placement, build-up, and temporary resin crown cemented. (e) One-year control radiograph showing a periapical radiolucency located on the mesial root. (f) Fracture line of the mesiobuccal root localized buccally. (g) Deep probing defect. (h) Radiograph obtained after hemisection and extraction of the mesial root. (i, l) Extracted root showing a long itudinal vertical root fracture. (m) Six months of follow-up radiograph
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F1
A preoperative periapical radiograph showed a short root canal filling in the mesial and distal previ-ously treated roots (Fig. 1a). In the first visit, after rubber dam placement, the remaining carious tissue was completely elim-inated, and a resin composite built-up was performed in order to obtain a four-wall access cavity for proper isolation and irrigation (Fig. 1b). Paul, MN, USA) was used to fill the access cavity (Fig. 1c), and in the second visit, a fiber-reinforced composite root canal post (DT Light Post; VDW) was cemented in the distal canal using a three-step dental adhesive system with its activator (Scotchbond Multipurpose; 3M Espe, Seefeld, Germany) and a dual-curable resin composite cement (Virage Dual; Sweden & Martina) photopolymerized for 2 min (Fig. 1d). After 1 year of travel outside Italy, the patient returned with-out the temporary crown (Fig. 1e). The tooth was painful on percussion and palpation, reporting pain during mastication; there was also one deep probing of 7 mm, extending beyond the physiological 2-3 mm depth and a fracture line of the mesial root localized buccally (Fig. 1f, Fig. 1g). The periapical radiograph showed a widening of the root canal space in the coronal part of the mesial root, suggesting VRF and a small periapical radiolucency in the mesial root (Fig. 1e). After a written informed consent to the treatment procedure, the mesial root was extracted after tooth hemisection (Fig. 1h, Fig. 1i, l), and after 1 week, the remaining distal root and the mandibular left second premolar were prepared and temporizated with a temporary resin bridge. A 6-month clinical and radiographic control showed bone and periodon-tal healing without symptoms (Fig. 1m).
(a) Composite images of the complete buccolingual fracture in the coronal third. (b, c) Fracture line in the buccal view (H&E and B&B stain, 100x). (d) Magnification of the area underlined in c and d show in bacteria along the fracture line (B&B stain, 400x)
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F2
Histologically, a complete fracture was shown in the coronal third of the root extending on the buccolingual plane (H&E stain, Fig. 2a, Fig. 2b). Bacteria aggregated in biofilm were visible in the internal fracture line on both sides of the same slices (B&B stain, Fig. 2c, Fig. 2d).
(a) In the middle third, the vertical root fracture is visible only in the buccal side (B&B stain, 40x). (b) Is thmus with traces of filling material and sealer without bacteria (B&B stain, 400x). (c, d) Mesiobuccal and mesiolingual canals in horizontal sections (B&B stain, 100x)
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F3
In the middle third, the fracture was visible only in the buccal side (B&B stain, Fig. 3a). Root canals and isth-mus seen in the horizontal sections of the middle third of the root showed a good cleaning with few traces of filling material without the presence of bacteria (Fig. 3b, Fig. 3c, d).
(a, b, c, d) Necrotic tissues and bacteria present in the apical area of the buccal canal (H&E stain, a=40x, b=400x and B&B stain, a=40x, b=400x). (e, f) Lingual canal: tissues in the main and lateral canal (H&E stain, e=40x and B&B stain, f=400x)
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F4
The vertical sec-tions of the apical 3 mm showed the presence of bacteria and necrotic tissue in the buccal canal (Fig. 4a, Fig. 4b, c, d) and tissues in the main and lateral canals lingually (Fig. 4e, Fig. 4f).