Restor Dent Endod.  2020 Aug;45(3):e27. 10.5395/rde.2020.45.e27.

The application of “bone window technique” using piezoelectric saws and a CAD/CAM-guided surgical stent in endodontic microsurgery on a mandibular molar case

• Kim U
• Kim S
• Kim E

• KMID: 2512018
• DOI: http://doi.org/10.5395/rde.2020.45.e27

Abstract

Apical surgery for a mandibular molar is still challenging for many reasons. This report describes the applications of computer-guided cortical ‘bone-window technique’ using piezoelectric saws that prevented any nerve damage in performing endodontic microsurgery of a mandibular molar. A 49-year-old woman presented with gumboil on tooth #36 (previously endodontically treated tooth) and was diagnosed with chronic apical abscess. Periapical lesions were confirmed using cone-beam computed tomography (CBCT). Endodontic microsurgery for the mesial and distal roots of tooth #36 was planned. Following the transfer of data of the CBCT images and the scanned cast to an implant surgical planning program, data from both devices were merged. A surgical stent was designed, on the superimposed three-dimensional model, to guide the preparation of a cortical window on the buccal side of tooth #36. Endodontic microsurgery was performed with a printed surgical template. Minimal osteotomy was required and preservation of the buccal cortical plate rendered this endodontic surgery less traumatic. No postoperative complications such as mental nerve damage were reported. Window technique guided by a computer-aided design/computer-aided manufacture based surgical template can be considerably useful in endodontic microsurgery in complicated cases.

Keyword

Endodontic microsurgery; Bone window; Surgical guide; Computer-aided design/ Computer-aided manufacturing; Piezoelectric surgery

Figure

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  Figure 1 (A) The clinical image of tooth #36 with the sinus tract on buccal gingiva (yellow arrow). (B) The initial periapical radiograph of tooth #36 showing periapical lesions and gutta percha tracing revealing the origin of the sinus tract was the distal root of tooth #36.

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  Figure 2 (A) Scanning data of the cast. (B) Cone-beam computed tomography (CBCT) image of the tooth uploaded to the surgical planning software. (C) Superimposition of the scanned cast and the CBCT image. (D) The coronal portion of the scanned cast above the level of the marginal gingiva and the gingival portion of the CBCT data were selected and merged. (E) The initial design of the surgical template without window. (F) The final design of the surgical template with window. (G, H) The buccal and the occlusal view of the 3D printed surgical template for endodontic surgery on tooth #36.

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  Figure 3 (A) After flap reflection, metal foramen and mental nerve was identified. (B) A groove was made using the piezoelectric saw on the coronal side of the mental foramen to protect it. (C) A KP1 retractor was placed on the groove. (D) The surgical template was positioned on tooth #36. (E) Guided osteotomy for preparation of the cortical window was performed using piezoelectric saws. (F) Bone preparation for the cortical window. (G) Uncovered area of the lesion and the apices of the roots. (H) The resected root surface inspected under high magnification. An isthmus was observed on the mesial root. (I) The resected root surface inspected under high magnification. An isthmus was observed on the distal root. (J, K) Root-end filling with Retro MTA on the mesial root and the distal root were confirmed under high magnification. (L) Allogenic bone was grafted and cortical bone was repositioned. (M) The postoperative periapical radiograph.

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  Figure 4 (A) The 6 months follow-up clinical image. (B) The 6 months follow-up periapical radiograph. (C) The 12 months follow-up periapical radiograph.

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