• Aucun résultat trouvé

Cone beam computed tomography imaging in dental implants : a primer for clinical radiologists

N/A
N/A
Protected

Academic year: 2022

Partager "Cone beam computed tomography imaging in dental implants : a primer for clinical radiologists"

Copied!
41
0
0

Texte intégral

(1)

Author Information

Seminars in Musculoskeletal Radiology

Cone Beam CT Imaging in Dental Implants: A Primer for Clinical

Radiologists

Anja Bernaerts, MD 1; Lieven Barbier, DDS,PhD 2; Johan Abeloos, MD, DMD, FEBOMFS 3; Tom De Backer, MD 3; Frederik Bosmans, MD. 4; Filip M. Vanhoenacker, M.D.,PhD 4,5,6; Jan Casselman, MD,PhD. 1,76 ,87

1. Department of Radiology, GZA Hospitals, Antwerp, Belgium

2. Training Center for Dental Students of the KU Leuven, AZ Sint-Jan Brugge-Oostende AV, Bruges, Belgium

3. Department of Maxillo-Facial Surgery, AZ Sint-Jan Brugge-Oostende AV, Bruges, Belgium

4. Department of Radiology, Antwerp University Hospital, Edegem, Belgium and Faculty of Medicine and Health Sciences, University of Antwerp, Belgium

5. Department of Radiology, AZ Sint-Maarten, Mechelen, Belgium

(2)

6. Department of Radiology, Ghent University Hospital, Ghent, Belgium 7. Faculty of Medicine and Health Sciences, Ghent University, Belgium

8. Department of Radiology, AZ Sint-Jan Brugge-Oostende AV, Bruges, Belgium 9. University Ghent, Belgium

Address for correspondence and reprint requests:

Anja Bernaerts, MD GZA Hospitals Antwerp Department of Radiology

Oosterveldlaan 24, 2610 Wilrijk, Belgium E-mail: anja.bernaerts@gza.be

KEYWORDS

4Cone-beam computed tomography (CBCT)

- 4Dental Implants

4– Alveolar Ridge Augmentation - 4Implant failure

-4 Imaging

(3)
(4)

ABSTRACT

With the introduction of cone-beam CT (CBCT) into dentistry in the nineties of last century, radiologists have become more frequently involved in dental implant planning. This article will give an overview as to what information should be included in a radiology report in order to achieve a successful implantation.

The justification to use CBCT during the preoperative planning phase is based upon the need to evaluate patient-specific anatomy in detail (general condition of the jaw, bone quantity and bone quality), the application of more advanced surgical techniques (maxillary sinus augmentation procedure, zygomatic implants) and the integrated presurgical planning and virtual patient approach.

Postoperatively, CBCT is used when implant retrieval is anticipated and 2-dimensional radiographs have not provided sufficient information, for evaluation of graft healing or to assess complications, mostly related to neurovascular trauma.

(5)

MANUSCRIPT FILE

With the introduction of cone-beam CT (CBCT) into dentistry in the nineties of last century, radiologists have become more frequently involved in dental implant planning. Considering the higher resolution of this technique, its lower radiation dose and reduced cost for patients -compared to multidetector CT-, the use of 3D information generated by CBCT in diagnosis and treatment planning has been growing rapidly. This article will give an overview as to what information should be included in a radiology report in order to provide the surgeon with the necessary information to achieve a successful implantation.

1. Imaging in Dental Implant Treatment Planning

The justification to use CBCT during the preoperative planning phase is based upon the need to evaluate patient-specific anatomy in detail (identification of critical anatomic boundaries, evaluation of bone morphology, volume and quality), the application of more advanced surgical techniques (grafting, zygomatic implants) and the integrated presurgical planning and virtual patient approach.1

A complete and comprehensive report should be provided to the referring surgeon or dentist which will support the implant treatment plan (4Table 1). At first, a paragraph should contain a description of the general condition of the jaw and the proposed implant site to rule out the presence of any other and/or occult pathology. Next, measurements of the alveolar bone quantity are to be obtained in the edentulous regions where implants are likely to be placed also

(6)

taking into account the ridge morphology and proximity of vital structures. The importance of information on the bone quality (density) is still under discussion.2, 3, 4, 5, 6

General condition of the jaw:

At first, the radiologist should investigate the general condition of the jaw in order to evaluate the presence of clinically significant findings and /or unexpected pathologies within and beyond the region of interest. Such findings may include surgical changes (root canal procedures, extraction socket, etc …), inflammatory diseases (periodontal or endodontic peri-apical lesions, cysts, maxillary sinus, condensing osteitis, etc …), developmental anomalies (e.g. mandibular torus, sinus septa, etc …) and/or tumor and tumor-like conditions of the jaw. Most reports in literature regarding these findings -unrelated to the reason the CBCT was indicated- agree that the prevalence of incidental findings is estimated to be greater than 90%, and therefore find it essential to have each scan comprehensively reviewed by someone with advanced training in radiographic interpretation.7

Early implant failure has been shown to be closely related to previous infection and/or inflammation. Therefore, the region of interest should be examined prior to placement of an implant to evaluate for areas of residual inflammation as well as infection coming from adjacent teeth. This inflammatory disease, which causes resorption of bone, is readily seen on dental CT scans and can be divided into either periodontal, either endodontic or per-iapical disease. Endodontic disease refers to an acute (abscess) or chronic (granuloma) infection surrounding the root apex of the tooth as a consequence of deep dental caries or tooth fracture which allow bacteria to enter the pulp chamber and travel down the root canal to the apical foramen. Radiographically, it appears as a fairly well-defined radiolucency at the root apex, which is typically smaller than 1 cm in diameter (4Fig. 1). A chronic apical inflammatory

(7)

lesion can result in in a local osteosclerotic scar which has less vascularity and might compromise successful osseointegration.8 Periodontitis is another way in which bacteria can affect teeth by attacking the periodontal ligament. This infection, which starts as gingivitis, travels along the ligament, causing bone resorption and formation of a pathological periodontal pocket or space in which the infection propagates.1 In severe periapical and periodontal infections, sites must be thoroughly debrided prior to implant placement and (guided) bone regeneration is sometimes required to fill the bone-implant gap.8 Radiographically, these areas simply appear as areas of normal or sometimes more condense bone in sites that previously had a defect. This should not be confused with condensing osteitis. 9

CBCT is also valuable to evaluate the graft recipient site prior to maxillary sinus augmentation procedures in particular in the evaluation of maxillary sinus lateral wall thickness, the location of blood vessels, the evaluation for antral septa or antral pathology and to evaluate the patency of the sinus ostium.7 The presence of septa has been related to an increased risk for perforation of the Schneiderian membrane during sinus floor elevation.10 Active inflammation in the recipient site may predispose to graft failure, therefore chronic maxillary sinusitis also has to be eliminated or treated before a sinus lift.10 A pre-operative CBCT should also always include the osteomeatal complex (OMC). A sinus with an obstructed maxillary ostium should not be operated upon as the accumulated blood and fluid cannot evacuate properly and may lead to secondary infection and possible implant loss. In these cases, the possibility of functional endoscopic sinus surgery (FESS) should be considered prior to sinus lifting. 11

Bone Quantity

The second objective of imaging is to ascertain the bone quantity at the proposed implant sites including the following: ridge morphology (angulation of the alveolar process, presence of

(8)

undercuts), the relationship to critical anatomical structures (inferior alveolar canal, anterior loop and mandibular incisive canal, mental foramen, lingual canal, maxillary incisive/nasopalatine canal, nasal cavity, and maxillary sinus) and ridge dimensions (height and width).4 CBCT has been proven to be superior in this regard compared with other 2D imaging modalities.7

Following teeth loss and consequent lack of function, significant changes are taking place in the shape of the alveolar process in both, vertical and horizontal, axes. In general, this disuse atrophy of the alveolar process follows a predictable pattern. At first, resorption affects bone width and later on, also bone height, except in the posterior zone of the superior maxilla, where atrophy predominantly affects bone height.12 Many classifications of residual ridge morphology have been developed. The classification of CAWOOD & HOWELL is regarded as the most comprehensive one at present and is internationally recommended for standardization in reports on pre-prosthetic surgery (4Fig. 2).13

The pattern of disuse atrophy is different for maxilla and mandible. In the anterior maxilla the bone loss starts as a labial undercut. This is a concavity on the labial aspect of the alveolar process with an apparently bulbous alveolar crest (4Fig. 3a). In the edentulous posterior mandibular alveolar process lingualization of the crest is common, making the submandibular fossa more pronounced (lingual undercut) (4Fig. 3b). A labial or lingual undercut increases the risk of alveolar cortical plate perforation during insertion of dental implants, which may lead to hemorrhage, salivary gland injuries, infections and instability of the implant.14, 15

Next, measurements of the alveolar bone quantity are obtained in the edentulous regions where implants are likely to be placed. CBCT is a reliable tool for these implant-planning measurements.16 Measurements should be obtained on the cross-sectional images in the areas of interest. For full-arch reconstruction, this can be done in a tabular fashion. The height and width

(9)

are obtained from the cross-sectional images at approximately 1-cm intervals along the entire arch, or at the strategic implant positions. For full-arch reconstruction in the mandible, the strategic implant positions include the lateral incisors, first premolar regions just anterior of the mental foramen, and first molars. In case of a resilient bar- or ball-retained overdenture the canine regions are the strategic position. Use of radiopaque gutta-percha markers, implant simulation programs and CBCT-derived implant surgical guides also can help optimize implant planning.

The height of the mandibular bone must be obtained from the superior border of the inferior alveolar canal to the alveolar ridge (4Fig. 1b). The canal is often seen as an oval, thin rim of dense cortical bone around the nerve. The bone thickness (vestibule-lingual distance) is measured as the area of minimal disposable bone that will limit the size of the implant. The measurement is made at the uppermost portion of the alveolus from the vestibular surface to the lingual cortical surface. If the ridge is pointed, one might state this rather than give an exact measurement. At the level of the maxilla, the measurements are made from the alveolar crest to the floor of the nasal fossa anterior or to the floor of the maxillary sinus posterior (4Fig. 3a).

The width is measured in the same way as in the mandible, from the inner vestibular cortical border to the inner palatine cortical border.12

In general, to decrease the probability of dental implant failure, it is estimated that the bone implant site needs to be at least 9 mm in height and 5 mm in width. A 2 mm safety zone between the apical part of the implant and upper border of the inferior alveolar canal is highly recommended. Implants also should be surrounded by minimum of 1mm bone, ideally 2 mm, especially in the labial aspect of maxillary anterior teeth.9, 12

In the pre-surgical analysis for zygomatic implants, the dimensions of the zygomatic bone should also be taken into account as well as the outer curvature of the maxillary bone.9

(10)

Bone Quality

Bone quality has been suggested as one of the main factors influencing implant therapy success. Areas of lesser bone quality have exhibited higher failure rates and weaker primary stability values.17 Bone quality may be assessed either during bone drilling for implant placement either by pre-operative imaging.

The applicability of quantitative gray values (GVs) in CBCT-derived density measurements has been the subject of extensive research as CBCT does not provide standardized HU. However, the great variability of these GVs -owing to various reasons that are inherently associated with this technique (i.e. the limited field size, relatively high amount of scattered radiation and limitations of currently applied reconstruction algorithms) -make a quantitative use of GVs in CBCT not useful for estimation of HUs at this time. In addition, recent research and clinical findings have shifted the paradigm of bone quality from a density-based analysis to a structural evaluation of the trabecular bone .7, 17

A subjective assessment of bone quality on cross-sectional images can be done by various scoring systems like the widespread LEKHOLM-ZARB index.18 In this classification system, bone density can be radiographically subdivided into 4 types according to the amount of cortical and trabecular bone (4Fig. 4). This classification correlates significantly with the bone mineral density and primary stability of dental implants.9, 19 If a lower bone density profile is predicted, choosing an implant that allows for a cylindrical rather than a tapered drilling protocol and the ability to slightly undersize the last osteotomy before implant placement may allow for increased primary stability of the implant during surgical procedures.20

(11)

2. Post Procedure Evaluation of Implants

In the postoperative phase, CBCT may be indicated as an adjunctive imaging tool when clinical examination and conventional radiographs do not provide sufficient information about successful implantation. CBCT is mainly used postoperatively to evaluate implant integration, graft healing and to assess postoperative complications, mostly related to neuro- vascular trauma. In case implant retrieval is considered, CBCT is also mandatory.1

Implant anatomy and classification of dental implants by size

Dental implants are metallic cylinders that are surgically imbedded into the edentulous jaw to provide anchorage for a dental prosthesis. By doing so, patients can have artificial teeth that are fixed in the jaw, which provide an attractive alternative to the standard removable denture or can be used to stabilize a removable prosthesis. On imaging, the different parts of an implant are clearly visible (4Fig. 5). The fixture is the portion that is imbedded in the bone, and the abutment, which is held in place with the abutment screw, raises it above the level of the gingiva to permit the prosthesis to be screwed into the abutment.2

Implants can be radiographically classified into 3 groups according to their size namely conventional implants, maxillary graftless procedure implants and mini implants. Conventional (root-form) implants are by far most commonly used and can be divided into relatively long implants (8-13 mm) and relatively short implants (5-7 mm). Maxillary graftless procedure implants are long implants (30-52 mm), e.g. zygomatic (4Fig. 6) or pterygoid implants and are used in fully edentulous atrophied maxilla without the need for additional ridge augmentation procedures. This can be a simpler, less invasive and sometimes less time-consuming treatment

(12)

option for the patient and is usually used in situations where no bone graft is possible or wanted. Mini implants are another way to avoid bone grafting and can limited be used to retain a removable prosthesis.9

Osseointegration of implants

If implant failure is suspected due to lack of osseointegration, periapical radiography is still considered the standard technique to examine the extent of marginal bone loss. Evaluation for close apposition of the bone to the surface of each implant is primordial. Cross-sectional imaging should be performed rather as adjunctive imaging tool in specific indications, for which clinical and two-dimensional radiographs have not provided sufficient information (4Fig. 7). CBCT has the benefit of visualizing the vestibular and oral aspects of the dental implant and has shown to have an acceptable correlation with histological measurements.4, 21, 22

One important issue that limits CBCT imaging for the diagnosis of peri-implant bone defects are the problem of artifacts such as blooming of the implant with enlargements easily reaching a third of the implant diameter. Other reported artefacts are streaks and black bands. In areas where the thin vestibular bone plate needs to be observed, blooming artefacts may even bias diagnosis. Artefacts are reported to be even worse with denser material and are thus more pronounced with implants in zirconium than in titanium.1, 7 Only a couple of commercially available CBCT devices are delivering images that are almost free of visible artefacts in the peri-implant vicinity. Moreover, the resulting image quality will still depend on the local situation and on the number and relative density of the metals in the field of view and/or the entire orofacial area.4

Definitions of successful implantation have typically included a threshold for expected peri- implant marginal bone loss. According to Albrektsson’s criteria marginal bone loss should not

(13)

exceed 1.5 mm during the first year of function and should be less than 0.2 mm per year thereafter. In 1999, a consensus report from the European Workshop on Periodontology modified Albrektsson’s criteria to indicate that no more than 2 mm of bone loss should occur during the first 5 years after installation of the prosthesis. 6

Graft materials and procedures

Normal extraction socket healing can lead to a loss of up to 50 % of bone volume within 6 months after extraction. Therefore, grafting at time of extraction or after extraction site healing, is often essential prior to implant placement. Different osteo-inductive and osteoconductive graft materials can be used in the alveolar process augmentation. The choice of graft materials depends on timing of the implant but also on the surgeons’ personal experience and national reimbursement differences. Autografts, in which the graft material comes from patient’s own tissue, is often referred to as gold standard for bone grafting. Particulate grafts generally present as a conglomerate with ground glass opacity within the bone defect on imaging. However, radiopacity will depend on the type of graft material which is used. Xenografts (e.g. bovine grafts) and synthetic grafts tend to be more radiopaque whereas allografts (human graft material) are less radiopaque. Adjunct materials which are used to enhance wound healing and regeneration such as resorbable membranes to prevent ingrowth of gingival epithelial and connective tissue cells and autologous growth factors are not radiographically visible.9

Different augmentation procedures can be considered to increase the amount of bone available for dental implants such as socket grafting (4Fig. 8), ridge augmentation and sinus floor elevation.9

In ridge augmentation, the volume of the alveolar ridge can be increased by particulate graft or block graft. The latter uses a solid block of cortical or cortico-cancellous bone to improve

(14)

dimensions of bone in deficient areas. Fixation screws are used to secure the block graft (4Fig.

9).

Maxillary sinus augmentation procedure (sinus lift) is a surgical procedure in which bone is grafted into the maxillary sinus in order to increase bone height for subsequent implant placement (4Fig. 10). The access to the maxillary sinus can be made through a window in the lateral wall of the sinus (lateral window approach) or by an opening in the floor of the sinus (crestal approach). A lateral window approach involves the creation of an osteotomy in the lateral wall of the maxillary sinus to produce a superiorly hinged bony flap, which is pushed inward within the sinus membrane. The space created in the floor of the maxillary sinus underneath the Schneiderian membrane (the mucous membrane that covers the inner part of the maxillary sinus cavity) is then packed with bone graft material to increase the height and width of the available bone. Maintaining the integrity of the Schneiderian membrane during elevation is important to confine the particulate graft, prevent infection and to preserve the ciliary function.2

Healing process of grafts materials

Periapical and panoramic radiographs can evaluate graft turnover and relative bone density compared to adjacent sites but cannot evaluate the buccolingual dimension of the graft site.

CBCT can evaluate graft healing and turnover in 3 dimensions making it the gold standard for graft procedure imaging.

As grafts heal, the particulate nature of the graft becomes less visible and trabeculation is seen throughout the graft. The grafted area becomes gradually continuous with adjacent native bone (4Fig. 8). In nonhealing grafts, low density areas will become visible within the grafted site indicative of soft tissue and the gap between the graft and the walls of the sinus will persist.

(15)

Rarely fragmentation of the graft material can be seen, suggestive of an infected graft (4Fig.

10) or perforation of the Schneiderian membrane (4Fig. 11).9

(16)

3. Imaging of Implant Complications

Despite careful planning, surgical complications can arise following implant placement. The evaluation of complications includes careful clinical examination and selected radiographic evaluation. 2-Dimensional radiographic techniques are adequate, in most cases, to confirm the position of an implant in relation to anatomic landmarks. However, 3-dimensional CBCT imaging might be helpful for the diagnosis and management of specific postoperative complications such as neurovascular damage or postoperative infections in relation to the inserted dental implants.1, 4

Radiographic features of failure moreover do not always equal clinical failure. An implant for example can appear to protrude into the bony floor of the maxillary sinus, but in absence of symptoms and mucosal inflammatory changes in the sinus lining, this may be considered a successful implant. Therefore, communication between the members of the dental implant team (surgeon restorative dentist and radiologist) is crucial in dealing with failures in case they should arise.9

Nerve canal injury

Improper radiographic implant planning and incorrect localization of neurovascular canals may lead to nerve canal injury with consequent neurosensory disturbances. When suspecting such a complication, CBCT can indicate the location of the implant and distinguish implant impingement, penetration and even complete obliteration of the canal.4

(17)

Important anatomical landmarks for maxillary implants are the nasopalatine canal and foramen, especially for central incisors. Asymmetric position, variation in number (paired, fused or multiple) and size can be predisposing factors for canal injuries and suboptimal osseointegration. The greater palatine foramen and canal are important when considering pterygoid implants. Literature so far didn’t report cases of symptomatic injury of the anterior superior alveolar canal (ASAC or canalis sinuosus) or its accessory canals.9

In case of mandibular implants, variations of the inferior alveolar canal (IAC) can predispose to nerve canal injury. Variations such as bifid canals, accessory mental foramina or posterior location of the mental foramen should be correctly mentioned in the radiological report. In case of sole interruption of the superior cortical border or incomplete traverse of the IAC, the clinical significance depends on the clinical symptoms (4Fig. 12).9

Bone perforation (nasal cavity, sinus, maxillary labial plate, lingual mandibular plate)

Implant protrusion into the maxillary sinus is not per se related to the development of long-term sinus complications. Acute sinusitis is the most commonly reported short-term complication, presenting with opacification and/or air-fluid level or air bubbles. A mucus retention cyst localized near the area of the implant is not considered as a failure in the absence of any clinical symptoms. In chronic sinusitis, thickening and sclerosis of the bony wall of the sinus can be noted. In rare cases, the implant can migrate into the sinus or nose cavity due to the negative pressure exerted by the sinus cavity and ciliary action of the sinus mucosal lining with development of an oro-antral or oronasal fistula (4Fig. 13).9

As in the maxillary sinus, not all radiographically apparent perforations of the nasal cavity are clinically significant even if the implant apex is in the mucosal lining. Nonetheless, if a portion

(18)

of the oral implant is left unsupported in the sinus, this means that the implant cannot osseointegrate to its full potential.9

Infection

Different types of infection adjacent to the implants can be seen on CBCT.

Peri-implantitis is caused by periodontal disease pathogens and presents with progressive (from crest to apex), well defined, vertical bone loss surrounding the implant.9 Treatment outcomes of peri-implantitis significantly depend on the severity of peri-implant bone loss upon diagnosis and the morphology of it. Early detection and accurate estimation of the morphology of peri- implant bone loss could help selecting the most appropriate intervention and thus improve the overall prognosis of compromised implants.23 CBCT can also have a relevant role in the determination of defect morphology and it may play an essential role in the therapeutic decision-making.24 Anatomically, peri-implant defects can be grouped similar to periodontal osseous defects, thus being primarily classified as “suprabony/horizontal” or

“intrabony/vertical”. Intrabony/vertical defects can further be categorized as a 1-, 2- or 3- walled defect (4Fig. 14). Dehiscence- and fenestration-type defects involve denudation of bone over the radicular or implant surface, a fenestration being a “window-like aperture”.23 The severity can be subclassified upon the defect depth from the implant neck or ratio of bone loss/total implant length ranging from “slight” (3-4 mm/<25% of the implant length), over

“moderate “(4-5 mm/≥25%-50% of the implant length) to “advanced” ( >6 mm/>50% of the implant length) (4Fig. 15).24 Current guidelines advocate intraoral radiographs to be taken when clinical peri-implant measures are indicative of disease. CBCT performs well in detecting peri-implant circumferential- intrabony or fenestration defects but less in depicting dehiscences.

Larger defect sizes exhibit a trend for better accuracy of detection by the use of CBCT imaging

(19)

and CBCT can have in this a relevant role in determination of the defect morphology (4Fig.

15).23, 24

Retrograde peri-implantitis (RPI), also called implant peri-apical lesion, occurs at the apical area of implants. Possible etiologies are overheating of bone during osteotomy, overloading of implant, pre-existing infection in bone, or implant contamination during insertion. RPI should be differentiated from osteotomy defects caused by the insertion of implants shorter than the prepared osteotomies.9

Osteomyelitis is an inflammation of bone and bone marrow due to bacterial infection. It is more often seen in the mandible than in the maxilla and typically presents with ill-defined bone loss surrounding the implant whether or not in combination with periosteal reaction, areas of sequestration or cloaca formation. The latter is a cortical defect that drains pus from within the medulla to the surrounding soft tissues.9

Osteonecrosis

Intravenously administrated bisphosphonates (BP) or monoclonal antibodies also might influence the implant success ratio, by preventing renewal of old and injured bone.17 Oral implants can however osseointegrate successfully in patients with a prior use of these types of medications. Some papers have reported medication-related osteonecrosis of jaws (MRONJ) cases in dental implant patients with a history of BP or denosumab use. Some factors such as systemic health status of the patient, type of medication, route of administration (intravenous BP has higher risk of osteonecrosis than oral BP), and longer duration of BP use could be determining factors with respect to MRONJ development in patients receiving dental implants.25 The best diagnostic clues are radiolucent bone destruction with a dense sequestrum resulting in a bone-within-bone appearance and sclerosis of the surrounding trabecular bone.26

(20)

The necrotic bone in case of MRONJ is very often surinfected by Actinomyces with an associated thickening and edema of soft tissues. Pathological fractures may appear in severe cases.

Fracture

Rarely implant body fracture can be seen horizontally in the main body of the implant or vertically in the crest module (neck) area. Dental implant fractures can occur due to occlusal forces, bone resorption, or improper fit of a prosthesis (4Fig. 15).27

Conclusion

In summary, CBCT offers numerous tangible clinical benefits in the pre- and post-operative evaluation of dental implant placement and allows the dentist and maxillofacial surgeon to further improve clinical outcomes.

(21)

References:

1. Jacobs R, Salmon B, Codari M, Hassan B, Bornstein MM. Cone beam computed tomography in implant dentistry: recommendations for clinical use. BMC Oral Health.

2018 May 15;18(1):88.

2. Abrahams JJ. Dental CT imaging: a look at the jaw. Radiology. 2001 May;219(2):334- 45.

3. Al-Ekrish AA. Radiology of Implant Dentistry. Radiol Clin North Am. 2018 Jan;56(1):141-156.

4. Bornstein MM, Horner K, Jacobs R. Use of cone beam computed tomography in implant dentistry: current concepts, indications and limitations for clinical practice and research. Periodontol 2000. 2017 Feb;73(1):51-72.

5. Bernaerts A, Vanhoenacker FM, Chapelle K, Hintjens J, Parizel PM. The role of dental CT imaging in dental implantology. JBR-BTR. 2006 Jan-Feb;89(1):32-42.

6. Yepes JF, Al-Sabbagh M. Use of cone-beam computed tomography in early detection of implant failure. Dent Clin North Am. 2015 Jan;59(1):41-56.

7. Rios HF, Borgnakke WS, Benavides E. The Use of Cone-Beam Computed Tomography in Management of Patients Requiring Dental Implants: An American Academy of Periodontology Best Evidence Review. J Periodontol. 2017 Oct;88(10):946-959.

8. Quirynen M, Gijbels F, Jacobs R. An infected jawbone site compromising successful osseointegration. Periodontol 2000. 2003;33:129-44.

9. Tamimi D, Koenig L, Al-Ekrish A, Rathi S, Schetritt A, Bajunaid S, Sawisch T, Angel I, Chenin D. Specialty imaging: Dental implants. Amirsys Inc.-Elsevier, Altona (Australia); 2014

(22)

10.Zijderveld SA, van den Bergh JP, Schulten EA, ten Bruggenkate CM. Anatomical and surgical findings and complications in 100 consecutive maxillary sinus floor elevation procedures. J Oral Maxillofac Surg. 2008 Jul;66(7):1426-38.

11.Tavelli L, Borgonovo AE, Re D, Maiorana C. Sinus presurgical evaluation: a literature review and a new classification proposal. Minerva Stomatol. 2017 Jun;66(3):115-131.

12.Saavedra-Abril JA, Balhen-Martin C, Zaragoza-Velasco K, Kimura-Hayama ET, Saavedra S, Stoopen ME. Dental multisection CT for the placement of oral implants:

technique and applications. Radiographics. 2010 Nov;30(7):1975-91.

13. Cawood JI, Howell RA. A classification of the edentulous jaws. Int J Oral Maxillofac Surg. 1988 Aug;17(4):232-6.

14. Zhang W, Skrypczak A, Weltman R. Anterior maxilla alveolar ridge dimension and morphology measurement by cone beam computerized tomography (CBCT) for immediate implant treatment planning. BMC Oral Health. 2015 Jun 10; 15:65.

15. Nickenig HJ, Wichmann M, Eitner S, Zöller JE, Kreppel M. Lingual concavities in the mandible: a morphological study using cross-sectional analysis determined by CBCT. J Craniomaxillofac Surg. 2015 Mar;43(2):254-9.

16.Suomalainen A, Vehmas T, Kortesniemi M, Robinson S, Peltola J. Accuracy of linear measurements using dental cone beam and conventional multislice computed tomography. Dentomaxillofac Radiol. 2008 Jan;37(1):10-7.

17. Pauwels R, Jacobs R, Singer SR, Mupparapu M. CBCT-based bone quality assessment:

are Hounsfield units applicable? Dentomaxillofac Radiol. 2015;44(1):20140238.

18. Lekholm U, Zarb GA. Patient selection and preparation. In: Branemark P-I, Zarb GA, Albrektsson T, eds. Tissue integrated prosthesis; osseointegration in clinical dentistry.

Chicago: Quintessence; 1985. pp. 199–209.

19. Triches DF, Alonso FR, Mezzomo LA, Schneider DR, Villarinho EA, Rockenbach MI, Teixeira ER, Shinkai RS. Relation between insertion torque and tactile, visual, and

(23)

rescaled gray value measures of bone quality: a cross-sectional clinical study with short implants. Int J Implant Dent. 2019 Feb 11;5(1):9

20.Scherer MD. Presurgical implant-site assessment and restoratively driven digital planning. Dent Clin North Am. 2014 Jul;58(3):561-95.

21.Corpas Ldos S, Jacobs R, Quirynen M, Huang Y, Naert I, Duyck J. Peri-implant bone tissue assessment by comparing the outcome of intra-oral radiograph and cone beam computed tomography analyses to the histological standard. Clin Oral Implants Res.

2011 May;22(5):492-9.

22.Silveira-Neto N, Flores ME, De Carli JP, Costa MD, Matos FS, Paranhos LR, Linden MSS. Peri-implant assessment via cone beam computed tomography and digital periapical radiography: an ex vivo study. Clinics (Sao Paulo). 2017 Nov;72(11):708- 713.

23.Pelekos G, Acharya A, Tonetti MS, Bornstein MM. Diagnostic performance of cone beam computed tomography in assessing peri-implant bone loss: A systematic review.

Clin Oral Implants Res. 2018 May;29(5):443-464.

24.Monje A, Pons R, Insua A, Nart J, Wang HL, Schwarz F. Morphology and severity of peri-implantitis bone defects. Clin Implant Dent Relat Res. 2019 Aug;21(4):635-643.

25. Chadha GK, Ahmadieh A, Kumar S, Sedghizadeh PP. Osseointegration of dental implants and osteonecrosis of the jaw in patients treated with bisphosphonate therapy: a systematic review. J Oral Implantol. 2013 Aug;39(4):510-20.

26.Baba A, Goto TK, Ojiri H, Takagiwa M, Hiraga C, Okamura M, Hasegawa S, Okuyama Y, Ogino N, Yamauchi H, Kobashi Y, Yamazoe S, Munetomo Y, Mogami T, Nomura T. CT imaging features of antiresorptive agent-related osteonecrosis of the jaw/medication-related osteonecrosis of the jaw. Dentomaxillofac Radiol. 2018 May;47(4):20170323.

(24)

27.Clark D, Barbu H, Lorean A, Mijiritsky E, Levin L. Incidental findings of implant complications on postimplantation CBCTs: A cross-sectional study. Clin Implant Dent Relat Res. 2017 Oct;19(5):776-782.

Figures and Tables

Table 1: Template for a comprehensive structured report in treatment planning

A complete and comprehensive report in treatment planning should include the following:

 General condition of the jaw

o Partially or completely edentulous

o Surgical changes (root canal procedures, extraction sockets)

o Inflammatory disease (periodontal or endodontic peri-apical lesions, cysts, maxillary sinus, condensing osteitis)

o Developmental anomalies (e.g. mandibular torus, sinus septa) o Tumor and tumor-like conditions of the jaw

 Bone quantity

o Ridge morphology (angulation/undercuts)

o Relationship to critical structures (nerves, vessels, roots, nasal floor and sinus cavities)

o Ridge dimensions

 Bone quality

(25)

Fig. 1:

(a: ) Cross-sectional dental CBCT image of the mandibular 1st molar tooth with prior partial root canal treatment and crown placement. There is a well-defined but not corticated radiolucency at the tooth apex compatible with a periapical abscess from recurrent endodontal disease (arrow). Note the surrounding zone of condensing osteitis (arrowheads).

(b: ) Cross-sectional dental CBCT image of the mandible in the same patient showing a good bone regeneration after tooth extraction and debridement without any signs of residual infection and with the maintenance of adequate dimensions of the alveolar ridge. The distances between the alveolar crest and the mandibular canal (long double arrow) (15 mm) and the width of the alveolar ridge at its apex (short double arrow) (8 mm) have been measured.

(26)

Fig. 2:

Graphic illustration of the CAWOOD & HOWELL classification in the maxilla (Aa) and mandible (Bb).

Class 1- dentate bone.

Class 2 - immediately post extraction.

Class 3- well-rounded ridge form, adequate in height and width.

Class 4 - knife-edge ridge form, adequate in height but inadequate in width.

Class 5 - flat ridge form, inadequate in height and width.

Class 6 - depressed ridge form, with variable basal bone loss evident.

(27)

Fig. 3:

CBCT cross section showing early atrophy of the alveolar process with the development of a labial undercut in the anterior maxilla (a) or a lingual undercut in the mandible (b) (arrowheads). In the anterior maxilla (a) there is a preservation of height (long double arrow) but there is an inadequate width in the middle third (short double arrow). In the mandible (b), width is preserved (horizontal double arrow) but height (vertical double arrow) is reduced with increased risk of alveolar cortical plate perforation during insertion of oral implants.

(28)

Fig. 4:

Graphic illustration of the LEKHOLM & ZARB classification Type 1: Entirely homogeneous compact bone

Type 2: Thick layer of compact bone surrounds core of dense trabecular bone Type 3: Thin layer of compact bone surrounds core of dense trabecular bone

Type 4: Thin layer of compact bone surrounds core of sparse, low-density trabecular bone.

(29)

Fig. 5:

Preliminary

Graphic illustration of the components of an implant that replaces a fixed tooth. The different parts of an implant used for this purpose are labeled (crown, abutment, abutment/implant interface, cover screw, implant platform, implant body, implant apex).

(30)

Fig. 6:

Panoramic radiograph shows a maxillary graftless treatment option using 5 zygomatic implants extending from the maxilla to the zygoma inferolateral to the orbits.

(31)

Fig. 7:

CBCT panoramic reformat (a) shows 4 conventional implants with healing abutments and apparent good positioning. CBCT cross section (b) however shows – in spite of the streak and black band artefact- a faciolingual malpositioning with complete labial plate dehiscence (arrowheads) of the implant replacing the right maxillary canine compromising the stability of the implant.

(32)

Fig. 8:

CBCT cross section immediate (a) and 6 months (b) following socket grafting procedure showing good consolidation and turnover of the graft. The outline of the extraction socket is less visible (arrowheads). The majority of the graft particles have been replaced by host bone (arrows).

(33)

Fig. 9:

(34)

Panoramic radiograph (a) showing a fully edentulous maxilla with severe disuse atrophy (Cawood class 6). Panoramic radiograph (b) of the same patient after bony reconstruction with autologous calvarian bone grafts and simultaneous placement of six provisional implants. Small fixation screws are also visible. Panoramic reformatted (c) and axial (d) CBCT images 6 months after surgery shows the healing of the block graft which has joined with the host bone resulting in adequate positioning and osseointegration of the implant- supported full-arch reconstruction.

(35)

Fig. 10:

Axial CBCT (a) shows a bilateral sinus augmentation procedure with synthetic grafts material appearing as a conglomerate with high attenuation in the maxillary sinuses.

There is opacification of the right maxillary sinus with sclerotic bone thickening of the wall indicative of a long-standing infection (arrowheads). CBCT cross sections (b, c)

(36)

also shows a low -density area visible within the graft (arrow) indicative of soft tissue within the graft and consistent with an infected graft. The persistent linear radiolucency between the graft and the sinus floor (arrowheads) suggest a nonhealing graft. In contrast to the right sinus, the left sinus (c) shows a normal aeration and the graft appears homogenous and continuous with adjacent bone (arrowheads).

(37)

Fig. 11:

CBCT panoramic reformat shows a diffuse spread of the bone graft particles (arrows) into the maxillary antrum due to perforation of the sinus/ Schneiderian membrane.

(38)

Fig. 12:

CBCT cross section shows the 1st molar implant denuding the superior cortex of the IAC (arrow). The significance depends on the clinical symptoms.

(39)

Fig. 13:

Sagittal (a) and axial (b) reformat of CT data shows a migrated implant in the nasal cavity engaging the left inferior nasal turbinate.

(40)

Fig. 14:

Preliminary

Graphic illustration of the vertical peri-implantitis morphologic defects in analogy with the periodontal disease classification. A vertical defect can be 1-, 2- or 3-walled depending on the number of bony walls left unaffected. In case of a 1-walled vertical defect, only the opposite bony wall of the adjacent tooth or implant remains intact (a).

In a 2-walled vertical defect, either the vestibular or the oral wall also remains unaffected (b). In a 3-walled vertical defect (c), only the wall adjacent to the implant is compromised.

(41)

Fig. 15:

CBCT panoramic (a) reformat shows an advanced circumferential peri-implantitis bone defect (arrowheads) of the implant replacing the left central incisor. Note an underlying fracture of the implant platform (arrow) and increased abutment-implant interface.

CBCT cross section (b) shows and advanced vertical bone loss, exceeding more than 50

% of the implant length (vertical double arrow), measured down from the abutment implant interface (horizontal double arrow).

(42)

Références

Documents relatifs

In order to measure the impact of the USD/EURO exchange rate changes on Algerian imports, we use a disaggregated approach with respect to five euro area countries:

Pour la production des VEMB en conditions de stress par l’ajout d’antibiotique, le milieu de culture Trypticase soya broth (TSB) (Cat.BD#211825) a été utilisé dans le but

The increased accumulation of C in soils brings multiple benefits: (1) promotes and sustains the formation of soil organic matter, (2) increases soil fertility because C binds to

Title Page Abstract Introduction Conclusions References Tables Figures ◭ ◮ ◭ ◮ Back Close.. Full Screen

Toutefois, au Centre Hospitalier Universitaire (CHU) d’Aalborg en 2015, les auteurs ont décrit une légère prédominance féminine avec un âge moyen de 52,6 ans, et une fréquence

Richard Steele’s sentimental comedy “The Conscious Lovers” (1722) gives an example of good behaviour by being exceedingly polite to the audience in the theatre through characters

Basic fibroblast growth factor (bFGF), an 18 kDa protein involved in angiogenesis, has been shown to stimulate endothelial cell proliferation and to promote the physical organization

This chapter looked at pre-existing social networks of youth involved in after- school programs, ways in which participation in afterschool activity alters these