10.59987/ads/2018.2.84-90
Aim: The aim of this paper is to present a case of mandibular cyst in proximity to the left inferior alveolar nerve and the adjacent teeth successfully treated with computer-guided bone lid technique.
Case presentation: A patient was referred to our Department with an asymptomatic radiolucent lesion in the left mandible coinciding with the edentulous site of a second premolar. The lesion was confirmed using cone-beam computed tomographic imaging. Two tooth-supported computeraided design/computer-aided manufacturing guided surgical templates were designed and produced to guide the piezoelectric tips on the planned osteotomy planes. The cystic lesion was accessed through a buccal bone lid fashioned using a piezoelectric device. The lesion was removed and the bone lid was returned to its original position and stabilized with fixation microplates.
Conclusions: Alveolar bone lesions can be treated successfully with bone lid techniques using piezosurgery. Computer-guided bone surgery offers the advantages of accurate and conservative surgical planning, enabling a safer and easier procedure.
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L.  De Stavola
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Annali di stomatologia
piezosurgery
Computer-guided bone lid osteotomy with piezosurgery
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Case Report
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L.  De Stavola
2018
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Computer-guided bone lid osteotomy with piezosurgery
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                                                                                                      Case report



    Computer-guided bone lid osteotomy with
    piezosurgery




                                                                                              li
                                                                                            na
    Stefano Sivolella1 DDS, PhD                           surgical planning, enabling a safer and easier
    Giulia Brunello1,2 DDS                                procedure.
    Andrea Fincato1 DDS
    Luca De Stavola1 DMD, MOM                             Key words: bone lid, CAD-CAM, computer-guided




                                                                                          io
                                                          surgery, customized templates, cyst, piezo-
                                                          surgery.
    1 University of Padova, Department of Neuroscien-




                                                                    az
    ces, School of Dentistry, Padova, Italy
    2 University of Padova, Department of Management      Introduction
    and Engineering, Vicenza, Italy
                                                          The removal of alveolar bone lesions or impacted




                                                                  rn
                                                          tooth in the mandible may lead to extensive residual
    Corresponding author:                                 bone defects, as a result of both the pathology or
    Giulia Brunello                                       tooth itself and the ostectomy, which must guarantee
    Department of Neurosciences, School of Dentistry,     an adequate access and visibility to the surgical field




                                                    te
    University of Padova                                  (1-3).
    Via Giustiniani 2                                     As alternative to the traditional ostectomy, the bone
    35128 Padova, Italy;                                  lid technique has been proposed as a valuable con-
                                                  In
    Department of Management and Engineering,             servative method for accessing alveolar bone dis-
    University of Padova                                  eases (2,4). Briefly, this technique consists in fash-
    Stradella S. Nicola 3                                 ioning and removing a bone window, which is subse-
    36100 Vicenza, Italy                                  quently repositioned at the end of the surgery. The lid
    Tel.: 00390498212040                                  is then fixed in place with miniplates (1,4), transfixa-
                           ni

    Fax: 00390498218229                                   tion screws (2), ligatures (5,6), or adhesive acrylic tis-
    E-mail: giulia-bru@libero.it                          sue (7). Rigid fixation may not be necessary in case
                                                          of high stability of the repositioned bone lid (2).
                         io


                                                          As compared to the traditional approach, this tech-
    Summary                                               nique provides better access and visibility to the sur-
                                                          gical site, allows to restore the integrity of the bony
                       iz



    Aim: The aim of this paper is to present a case of    wall avoiding secondary bone defects due to access
    mandibular cyst in proximity to the left inferior     osteotomies and, in cases of close proximity to the
    alveolar nerve and the adjacent teeth successfully    alveolar nerve, allows to easily identify and protect
          Ed




    treated with computer-guided bone lid technique.      the nerve reducing the risk of neurological damages
    Case presentation: A patient was referred to our      (1, 3, 8). The osteotomy for designing the bony lid
    Department with an asymptomatic radiolucent le-       can be performed with fissure burs (9), oscillating
    sion in the left mandible coinciding with the eden-   saws (10), microsaws (2), or piezosurgery (1, 3, 4, 8).
    tulous site of a second premolar. The lesion was      The use of the piezosurgery enables beveled, thin,
    confirmed using cone-beam computed tomo-              and precise osteotomies, and facilitates the reposi-
 IC




    graphic imaging. Two tooth-supported computer-        tioning and fixing of the bone lid (1). In addition, its
    aided design/computer-aided manufacturing guid-       use is particularly indicated when the lesion is in
    ed surgical templates were designed and pro-          proximity of delicate structures, such as the inferior
    duced to guide the piezoelectric tips on the          alveolar nerve, considering its selective and soft tis-
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    planned osteotomy planes. The cystic lesion was       sue sparing abilities, avoiding soft tissue injury also in
    accessed through a buccal bone lid fashioned us-      cases of accidental contact with the cutting tip (8, 11).
    ing a piezoelectric device. The lesion was re-        Beside the piezosurgery, computer-aided design and
    moved and the bone lid was returned to its origi-     computer-aided manufacturing (CAD-CAM) can be
©




    nal position and stabilized with fixation mi-         used to advantage in the bone lid technique, as they
    croplates.                                            have demonstrated their validity in various surgical
    Conclusions: Alveolar bone lesions can be treat-      procedures requiring individually guided osteotomies
    ed successfully with bone lid techniques using        (12-14).
    piezosurgery. Computer-guided bone surgery of-        The aim of this case report is to describe the applica-
    fers the advantages of accurate and conservative      tion of computer-guided surgery to controll the angle

    84                                                                         Annali di Stomatologia 2018;IX (2):84-90
    Computer-guided bone lid osteotomy with piezosurgery


    and depth of the osteotomy lines to use in fashioning     The Digital Imaging and Communication in Medicine
    a bone lid. A mandibular cyst proximal to the             (DICOM) datasets were processed with diagnostic
    mandibular canal and the adjacent teeth was treated       and analytical software (3Diagnosys ® 4.0,
    using two complementary CAD-CAM templates.                3DIEMME®, Como, Italy). Anatomical structures such
                                                              as the alveolar canal, the mental foramen, the mental
                                                              nerve and the dental roots in the area of the lesion
    Case




                                                                                                li
                                                              were identified. Ideal bone cutting planes were de-
                                                              fined (angle and depth) following specific targets,




                                                                                              na
    1) Case presentation                                      which included: performing the osteotomies as close
    A healthy 52-year-old male patient was referred to our    as possible to the roots of the adjacent teeth and the
    Department with a radiolucent lesion in the left          mental foramen, while avoiding any contact with them
    mandible coinciding with the edentulous site of a sec-    and not invading the periapical areas of the teeth; en-




                                                                                            io
    ond premolar. The patient was clinically asymptomatic     suring the maximal extension of the bone lid in rela-
    and the lesion was an incidental radiographic finding.    tion to the bone disease; creating a long bevel along
    Preoperative cone-beam computed tomography                the osteotomies; fashioning a bone lid of adequate
    (CBCT) (Fig. 1) revealed an unilocular radiolucent area   thickness and area. The projections of the planned




                                                                        az
    with well-defined margins proximal to the mental fora-    cutting planes defined the shape of the surgical guide
    men, mandibular canal and adjacent teeth. The lesion      (Fig. 2). The template’s lateral contours guide the
    was surrounded by bony walls at least 1 mm thick.         piezoelectric insert simply by applying pressure on it.
                                                              The final guide design, including the anchorage to the




                                                                      rn
    2) CAD-CAM workflow                                       adjacent teeth, was shaped using a CAD software
    The CAD-CAM SafeCut® workflow (SafeCut®, Guid-            (PlastyCAD, 3DIEMME®, Como, Italy). Two comple-
    edSurgery2.0 srl, Padova, Italy) was adopted (15,16).     mentary surgical guides were planned to facilitate the




                                                       te                                Figure 1. Panoramic view (a)
                                                                                         and axial view (b) obtained
                                                     In
                                                                                         from the preoperative CBCT.
                                                                                         An unilocular radiolucent
                                                                                         area is detectable in the pos-
                                                                                         terior left mandible in close
                                                                                         proximity to the mandibular
                               ni

                                                                                         canal and mental foramen.
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    Annali di Stomatologia 2018;IX (2):84-90                                                                        85
    S. Sivolella et al.




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    Figure 2. Preoperative osteotomy planning. The morphology of the surgical templates is designed so as to obtain os-
    teotomies at a safe distance about 1-1.5 mm from the adjacent teeth, the mental nerve, and the mandibular canal. The size




                                                                             rn
    of the bone lid was designed to be as ample as possible, avoiding the crestal area, for the placement of a delayed implant.


    surgical workflow, one for the upper osteotomy and              Discussion and conclusion
    one for lateral and lower osteotomies. The surgical
    guides were made of medical polyamide by means of
    a CAM process (3Dfast srl, Padova, Italy).
                                                          te        Achievements in three-dimensional radiographic
                                                                    imaging techniques and computer technologies, to-
                                                        In
                                                                    gether with advances in CAD-CAM techniques en-
    3) Surgery                                                      able digital data from a surgical plan to be trans-
    Surgery was performed under local anesthesia and                ferred to real clinical settings using computer-milled
    sedation. A full-thickness flap was reflected buccally          templates or stereolithographic surgical guides (17).
                              ni

    and adequate access to the alveolar bone lesion was             The proposed method provided the means to control
    assured by means of a buccal bone lid. The surgical             osteotomy design predictably and very safely and
    guides were inserted and stabilized by anchoring                accurately, extending the applicability of the bone lid
                            io


    them to a tooth. Piezosurgery ® (Mectron Medical                technique to sites where there is a risk of damaging
    Technology, Carasco, Italy) was used in the bone                anatomical structures. Tooth-supported surgical tem-
    mode with the UNIVR tip (Mectron, Italy).                       plates can be positioned easily, and enable an un-
                          iz



    The osteotomies were completed by placing the side              equivocal insertion. They allow adequate bone lid di-
    of the piezoelectric insert facing against the outer            mensions to be obtained, thereby ensuring an ade-
    faces of the two surgical guides. The surgical tem-             quate access to the alveolar bone lesion, and a clear
            Ed




    plates unequivocally defined the direction of the cut-          identification of its extension during the surgical pro-
    ting action. The depth was established on volumetric            cedure. Predetermined wide beveled margins can be
    image analysis. In accordance with the preoperative             obtained, facilitating the repositioning of the bone lid
    plan, the mesial and distal cuts were made to a vari-           and increasing the contact surface at the bone-to-
    able distance of 1-1.5 mm from the adjacent teeth,              bone interface, which also improves the bone lid’s
    while the inferior cut was made at least 1.5 mm                 revascularization (1, 2, 4). The successful filling of a
 IC




    above the mental foramen (Fig. 3a-c). After its re-             residual alveolar defect with bone relies mainly on
    moval (Fig. 3d), the bone lid was placed in sterile             the achievement of a stable blood clot in a self-con-
    saline solution. The diseased tissue was removed                tained chamber (18), and the bone lid technique
    (Fig. 3e) and the buccal bone lid was put back in its           seems to favor this biological process.
C




    original position and stabilized with 1.3 mm fixation           The bone lid is usually repositioned and secured with
    microplates (Synthes GmbH, Oberdorf, Switzerland)               fixation microplates. Pre-plating can be done during
    (Fig. 3f). The gingival flap was then put back in place         the surgical procedure, before the bone lid is raised,
    and sutured. Postoperative CBCT scans revealed a                or the microplates can be fashioned in advance on a
©




    perfect match between the contours of the templates             stereolithographic model (19). Alternatively, custom-
    and the osteotomic lines performed (Fig. 4). The                made titanium CAD-CAM fixation plates can be man-
    histopathological findings were consistent with a               ufactured (13).
    residual cyst. No complication occurred. Bone lid               Computer-guided implant surgery is rapidly develop-
    healing and bone defect filling were assessed 1 year            ing and expanding (17). The use of customized CAD-
    after surgery on radiological follow-up (Fig. 5).               CAM surgical cutting guides has been described in

    86                                                                                   Annali di Stomatologia 2018;IX (2):84-90
    Computer-guided bone lid osteotomy with piezosurgery



     a                                                                b




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                                                                                                         io
     c                                                                d




                                                                                  az
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     e                                                                f
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    Figure 3. Surgical procedures. The two complementary surgical guides are shown in (a) and (b). (a) The first surgical guide
    is inserted and stabilized on the adjacent teeth. Inferior and lateral osteotomies are cut with the side of the piezoelectric in-
    sert (UNIVR) facing against the external inferior and vertical faces of the surgical guide; (b) the second guide is then insert-
    ed and the upper osteotomy is performed in much the same way; (c) mandibular buccal bone lid fashioned using piezo-
    surgery, prior to its detachment; (d) adequate access to the alveolar bone lesion is assured; (e) Residual alveolar bone de-
 IC




    fect after removal of the lesion. The mental nerve is clearly intact; (f) the buccal bone lid is put back in place and fixed with
    microplates.
C




    orthognathic procedures too (12,13,19). Milano et al.              In the bone regeneration field, Felice et al. (14) re-
    (20) reported using the piezocision technique as a                 ported using guided osteotomies in sandwich tech-
    combination of micro-incisions and localized piezo-                niques and inlay block procedures in the posterior at-
    electric bone surgery to accelerate orthodontic treat-             rophic mandible: they used a customized CAD-CAM
©




    ment in adult patients. Piezocision was combined                   polymethyl methacrylate surgical template obtained
    with the use of computed tomography. The depth and                 by milling. The Authors’ proposed surgical guide
    location of the corticotomies were planned on a three-             helped the surgeon to identify the most appropriate
    dimensional model of the arch, and a surgical guide                osteotomic path on the bone surface, but no 3D infor-
    was fashioned and used during the procedure to                     mation was provided on the axes of the cutting
    avoid damaging the dental roots.                                   planes.


    Annali di Stomatologia 2018;IX (2):84-90                                                                                      87
    S. Sivolella et al.



     a




                                                                                                     li
                                                                                                   na
                                                                                                 io
                                                                            az
     b




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                                                      In
                              ni
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    Figure 4. The first (a) and second (b) templates superimposed on the postoperative CBCT. The osteotomies coincide well
    with the templates’ surfaces.
            Ed




    Also autogenous mandibular bone harvesting apply-            In Kocyigit et al. (22), different piezosurgery tips
    ing computer-guided surgery was described. As in             were used for performing the osteotomies, for cyst
    the present work, bone osteotomy planes were de-             enucleation and apicoectomy, when required. No
    fined beforehand in order to produce a surgical guide,       complication occurred in any of the patients treated
    which imposed the 3D working direction to the bone-          using piezosurgery for radicular cyst enucleation; in-
    cutting instrument (15,16).                                  stead in the conventional surgery group, complica-
 IC




    As for implant surgery, time has to be spent on pre-         tions were reported, including intraoperative and
    operative planning (17), and it is not easy to estimate      postoperative bleeding, perforation of the cyst ep-
    the cost-effectiveness of this approach by compari-          ithelium and difficulties in its complete removal, and
    son with conventional surgery, with or without bone          recurrence.
C




    lids.                                                        In a case of giant dentigerous cyst associated with
    The use of piezosurgery for the treatment of alveolar        an ectopic maxillary third molar (23), several piezo-
    bone cysts has been described (21-23).                       surgery tips were successfully used for sinus win-
    In a randomized clinical study comparing piezo-              dow osteotomy, for the atraumatic dissection of the
©




    surgery and conventional rotatory surgery for the            cyst and for the extraction of the impacted tooth.
    enucleation of mandibular cysts, no lesion of the            The bone lid technique has been validated as a
    mandible nerve was detected when piezosurgery was            method for preserving alveolar bone (2,4), so every
    used in combination with the bone lid technique. Con-        effort should be made to improve this technique, in-
    ventional surgery with rotary instruments resulted in        cluding CAD-CAM applications based on 3D imag-
    8% hypesthesia at least up to one week (21).                 ing.


    88                                                                                Annali di Stomatologia 2018;IX (2):84-90
    Computer-guided bone lid osteotomy with piezosurgery


                                                                                                               Figure 5. CT scan, axial
                                                                                                               view, 1 year after surgery.
                                                                                                               The bone lid is integrated
                                                                                                               and no residual bone de-
                                                                                                               fect is detectable. Fixation
                                                                                                               screws and miniplates are
                                                                                                               in place.




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    Conflict of interest

                                                                 te      2.  Khoury F. The bony lid approach in pre-implant and implant
                                                                             surgery: a prospective study. Eur J Oral Implantol. 2013;6:375-
                                                               In            384.
    The Authors have no financial or personal relation-
                                                                         3. Chiapasco M, Flora A, Serioli L, Zaniboni M. The removal
    ships with people or organizations that might inappro-                   of deeply impacted lower third molars by means of the bone
    priately bias their work.                                                lid technique with piezoelectric instruments. Italian Journal
                                                                             of Dental Medicine. 2017;2:13-17.
                                ni

                                                                         4. Sivolella S, Brunello G, Berengo M, De Biagi M, Bacci C. Re-
    Acknowledgments                                                          habilitation with implants after bone lid surgery in the pos-
                                                                             terior mandible. J Oral Maxillofac Surg. 2015;73:1485-
    The Authors LDS and AF are the inventors of the                          1492.
                              io


                                                                         5. Biglioli F, Chiapasco M. An easy access to retrieve dental
    PCT/IB2014/061624 “Method for making a surgical
                                                                             implants displaced into the maxillary sinus: the bony window
    guide for bone harvesting” described in this
                                                                             technique. Clin Oral Implants Res. 2014;25:1344-1351.
    manuscript.
                            iz



                                                                         6. Lazaridis N, Tilaveridis I, Venetis G, Lazaridou M. Maxillary
                                                                             sinus osteoplasty with vascularized pedicled bone flap. Oral
                                                                             Surg Oral Med Oral Pathol Oral Radiol Endod. 2008;106:828-
    Ethical statement/confirmation of patients’                              832.
            Ed




    permission                                                           7. Balleri P, Veltri M, Nuti N, Ferrari M. Implant placement in
                                                                             combination with sinus membrane elevation without bio-
    The Authors confirm that the patient was fully in-                       materials: a 1-year study on 15 patients. Clin Implant Dent
                                                                             Relat Res. 2012;14:682-689.
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                                                                         8. Degerliyurt K, Akar V, Denizci S, Yucel E. Bone lid technique
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    ed taking photographs of the lesions and procedures.
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                                                                             Oral Med Oral Pathol Oral Radiol Endod. 2009;108:e1-5.
    The Authors confirm that any personal details con-                   9. Choi BH, Yoo JH, Sung KJ. Radiographic comparison of os-
    cerning the patient occurring in any part of the paper                   seous healing after maxillary sinusotomy performed with and
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©




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    90                                                                                           Annali di Stomatologia 2018;IX (2):84-90
