Use of cone beam computed tomography in implant dentistry: current concepts, indications and limitations for clinical practice and research

Assessing the frequency of deep lingual concavities in 826 posterior mandible sockets

PURPOSE

To evaluate the frequency of deep lingual concavities in the lower jaw, which can cause surgical complications while inserting dental implants.

METHODS

Cross-sections of the mandible alveolar ridge at the edentulous sockets were obtained via cone-beam computed tomography. Measurements were carried out using the freeware 'IC Measure' and based on the basic definitions of a previous study.

RESULTS

Most (767/826 = 93%) sockets had concavities of various degrees (30-90°), while 59 (7%) sockets had no concavity. However, the majority of the concavities (71%) were mild, with angles > 60°. The other 220 (26%) sockets had deeper concavities of <60°; among these, 12 (1%) had extremely deep concavities of <40°.

CONCLUSIONS

Only a few cases have deep lingual concavities that pose a high risk for lingual plate perforation during dental implantation.

Accuracy of cone-beam computed tomography is limited at implant sites with a thin buccal bone: A laboratory study

BACKGROUND

To evaluate whether buccal bone thickness (BBT), implant diameter, and abutment/crown material influence the accuracy of cone-beam computed tomography (CBCT) to determine the buccal bone level at titanium implants.

METHODS

Two implant beds (i.e., narrow and standard diameter) were prepared in each of 36 porcine bone blocks. The implant beds were positioned at a variable distance from the buccal bone surface; thus, resulting in three BBT groups (i.e., >0.5 to 1.0; >1.0 to 1.5; >1.5 to 2.0 mm). In half of the blocks, a buccal bone dehiscence of random extent ("depth") was created and implants were mounted with different abutment/crown material (i.e., titanium abutments with a metal-ceramic crown and zirconia abutments with an all-ceramic zirconia crown). The distance from the implant shoulder to the buccal bone crest was measured on cross-sectional CBCT images and compared with the direct measurements at the bone blocks.

RESULTS

While abutment/crown material and implant diameter had no effect on the detection accuracy of the buccal bone level at dental implants in CBCT scans, BBT had a significant effect. Specifically, when BBT was ≤1.0 mm, a dehiscence was often diagnosed although not present, that is, the sensitivity was high (95.8%), but the specificity (12.5%) and the detection accuracy (54.2%) were low. Further, the average measurement error of the distance from the implant shoulder to the buccal bone crest was 1.6 mm.

CONCLUSIONS

Based on the present laboratory study, BBT has a major impact on the correct diagnosis of the buccal bone level at dental titanium implants in CBCT images; in cases where the buccal bone is ≤1 mm thick, detection of the buccal bone level is largely inaccurate.

A review of virtual planning software for guided implant surgery - data import and visualization, drill guide design and manufacturing

Background

Virtual implant planning systems integrate (cone beam-) computed tomography data to assess bone quantity and virtual models for the design of the implant-retained prosthesis and drill guides. Five commercially available systems for virtual implant planning were examined regarding the modalities of integration of radiographic data, virtual dental models and the design of drill guides for guided implant surgery. The purpose of this review was to describe the limitations of these available systems regarding the import of imaging data and the design and fabrication of a drill guide.

Methods

The following software systems were examined regarding the import of imaging data and the export of the virtual implant planning for the design and fabrication of a drill guide with the help of two clinical situations requiring dental implant therapy: coDiagnostiX™, DentalWings, Canada (CDX); Simplant Pro™, Dentsply, Sweden (SIM); Smop™, Swissmeda, Switzerland (SMP); NobelClinician™, Nobel Biocare, Switzerland (NC); Implant Studio, 3Shape, Denmark (IST). Assessment criteria included data formats and management as well as the workflow for the design and production of drill guides.

Results

All systems have a DICOM-interface (“Digital Imaging and Communication in Medicine”) for the import of radiographic data. Imaging artefacts could be reduced but not eliminated by manual data processing. The import of virtual dental models in a universal format (STL: Standard Tesselation Language) was possible with three systems; one system could only be used with a proprietary data format.

All systems display three-dimensional surface models or two-dimensional cross-sections with varying orientation for virtual implant planning. Computer aided design and manufacturing (CAD/CAM) of drill guides may be performed by the user with the help of default parameters or solely by the provider of the software and thus without the influence of the clinician.

Conclusion

Data bases of commonly used implant systems are available in all tested software, however not all systems allow to plan and execute fully guided implant placement. An individual design and in-house manufacturing of the drill guide is only available in some software systems. However, at the time of publication most recent software versions showed flexibility in individual design and in-house manufacturing of drill guides.

Evaluation of cervical peri-implant optical density in longitudinal control of immediate implants in the anterior maxilla region

OBJECTIVE

This research aimed to longitudinally evaluate the optical density of peri-implant alveolar bone. The data acquired from study participants previously treated with 37 osseointegrated implants were analyzed utilizing the radiographic subtraction technique.

METHODS AND MATERIALS

The radiographic follow-ups were performed five times: at the implantation of the prostheses and after 15, 90, 180 and 360 days. Intraoral radiographs were obtained by the paralleling technique using individualized Hanshin-type positioners to guarantee the standardization of the images. The obtained digital images were aligned and equalized before they were submitted to the radiographic subtraction procedure.

RESULTS

A significant difference was found between the distal region of Group I (patients treated with osseointegrated implants who required extraction of the dental element) and the 360 day follow-up and the distal region of Group II (patients with healed alveolar sockets) in all follow-up analyses (p < 0.05). We did not observe a significant difference between the groups analyzed and other follow-ups concerning the subcrestal and middle third regions for both the mesial and distal variables (p > 0.05). There was a statistically significant difference in the distal sites [χ2 = 5,745,, p = 0.03], showing a significant association between time and the presence of bone resorption. This association was not shown on the mesial surface (p = 0.16).

CONCLUSION

We concluded that there was no statistically significant difference between groups I and II. Using this technique, we were able to quantitatively and qualitatively evaluate the changes in the proximal sites on the digital radiographic images for the analyzed data. Digital subtraction technology to measure peri-implant bone density is an accurate and reproducible technique for quantifying peri-implant bone reactions to different therapeutic modalities.

Custom Focal Trough in Cone-Beam Computed Tomography Reformatted Panoramic Versus Digital Panoramic for Mental Foramen Position to Aid Implant Planning

Objectives:

To compare the linear measurements from digital panoramic (DP) radiographs and cone-beam computed tomography (CBCT) volumes for the localization of the mental foramen (MF).

Material and Methods:

Thirty-one patients with panoramic and CBCT radiographs depicted on the same machine were analyzed. The vertical and horizontal positions of the MF were compared by the differences in distances measured from reference points to the boundaries (tangents) of the MF in digital panoramic (DP) and CBCT reformatted panoramic (CRP) views. The vertical position of MF was also analyzed on CBCT oblique coronal views (CORO) and compared with its corresponding distances on DP and CRP views.

Results:

Statistically significant differences (P < 0.05) were found in all compared measurements between CRP and DP views. In addition, the vertical distance (Y1) compared between DP, CRP, and CORO views also showed a statistically significant measurement discrepancy in the mean distance (P < 0.000) with the highest mean difference of 1.59 mm (P < 0.05) was attained from Y1 (DP-CORO). Inter- and intra-examiner analysis indicated a high level of agreement for all measurements.

Conclusion:

The mean values of discrepancies in measurements between DP and CRP views for horizontal and vertical linear measurements were clinically tolerable. Nevertheless, significant differences in the vertical MF position were detected between the panoramic views (DP, CRP) and the coronal views (CORO). This implies that the use of coronal view measurements during implant planning might reduce the risk of neurovascular injuries.

Diagnostic Potential of Panoramic Radiography and CBCT in Detecting Implant-Related Ex Vivo Injuries of the Inferior Alveolar Canal Border

The aim of this ex vivo study was to compare the diagnostic performances of panoramic radiography and cone beam computerized tomography (CBCT) in detecting implant-related injuries of the inferior alveolar canal. Monocortical bone windows were created in 60 fresh sheep hemimandibles, the inferior alveolar canals were revealed and 120 dental implants were inserted. Three types of injuries, described as pilot drill damage (PDRILL), collapsing of the superior border of the canal (COLL), penetration of the implant tip into the canal (PENET) and one control group, were simulated. Standard (PANO) and dentition mode panoramic (PANO-DENT) images as well as CBCT data presented as multiplanar reconstruction (MPR) and cross-sectional (CROSS) views were evaluated by 6 observers who had also expressed their level of confidence to their final diagnosis. Intra- and interobserver agreement scores were rated good. The area under the curve (AUC) values and the confidence scores for CROSS and multiplanar reformation (MPR) views were both significantly higher than those of PANO and PANO-DENT (P < .05 for each) in PDRILL group. In COLL group, observers showed less confidence to PANO and PANO-DENT compared to CROSS and MPR techniques (P < .05 for each). No other significant differences were found. Within the limits of this experimental study, it can be suggested that the standard and dentition modes of panoramic radiography can be as effective as CBCT in the detection of penetrating and collapsing injuries, but multiplanar and cross-sectional views of the CBCT are more accurate than panoramic radiography in the detection of pilot drill injuries in sheep mandible.

Attitude in Radiographic Post-Operative Assessment of Dental Implants among Italian Dentists: A Cross-Sectional Survey

There is a lack of evidence in the attitude and prescribing practice of implantologists in dental implant post-operative assessment; therefore, the aims of this cross-sectional study were to investigate these habits and the knowledge about radiographic aspect of retrograde peri-implantitis (RPI) among Italian implantologists. A questionnaire was sent via email to dentists randomly selected from the register of implantology and oral surgery societies. It included three questions: the preferred X-ray after implant placement, the timing of post-operative assessment and the knowledge of the RPI radiographic representation. A final sample of 434 implantologists was included in the study. The majority of them (84.3%) perform a periapical X-ray as control radiograph and picked the correct radiographic representation of RPI (74.3%), without statistically significant differences (p > 0.05) for sex, age, years of working practice and number of implants placed per year. Just 47.7% of dentists perform a control radiograph at prostheses delivery, to establish a proper baseline. A statistically significant difference (p < 0.05) was detectable only for the number of implants placed per year, with dentists placing > 80 implants selecting the correct choice. To the best of authors’ knowledge, this is the first study to report data on attitude of implantologists in radiographic imaging after implant placement.

Cone beam computed tomography artefacts around dental implants with different materials influencing the detection of peri-implant bone defects

OBJECTIVES

To investigate the diagnostic accuracy of cone beam computed tomography (CBCT) for the diagnosis of peri-implant bone defects of titanium (Ti), zirconium dioxide (ZrO₂ ) or titanium-zirconium (Ti-Zr) alloy implants.

MATERIALS AND METHODS

Ti, Ti-Zr or ZrO₂ implants with two diameters (3.3 mm, 4.1 mm) and one length (10 mm) were inserted in the angle of the mandible of six fresh defrosted pig jaws. Out of the 12 implants inserted, 6 served in the test group with standardized buccal peri-implant bone defects, whereas 6 served as control without bone defects. CBCTs were performed with three acquisition protocols (standard, high and low dose) using two devices. Four observers analysed CBCTs as follows: (a) presence of a peri-implant defect; (b) presence of peri-implant artefacts and impact on defect diagnosis; and (c) linear measurements of buccal peri-implant defect including height and width (in mm).

RESULTS

CBCT device, CBCT settings, implant material, implant diameter and observer background did not significantly influence diagnostic accuracy. The sensitivity and specificity values were high for defect detection. ZrO₂ led to a lower than average diagnostic accuracy (0.781). The linear measurements of peri-implant defect were underestimated by <1 mm on average. The subjective impact of artefacts on defect diagnosis was significantly affected by implant material and observer background.

CONCLUSIONS

CBCT showed high diagnostic accuracy for peri-implant bone defect detection regardless of the device, imaging setting or implant material used. If CBCT is indicated to assess peri-implant bone disease, low dose protocols could be a promising imaging modality.

Development of an evidence-based clinical imaging diagnostic guideline for implant planning: Joint recommendations of the Korean Academy of Oral and Maxillofacial Radiology and National Evidence-based Healthcare Collaborating Agency

Purpose

This study was conducted to develop an evidence-based clinical imaging diagnostic guideline for implant planning, taking into account efficacy, benefits, and risks.

Materials and Methods

The guideline development process employed the adaptation methodology used for Korean clinical imaging guidelines(K-CIG). Core databases(Ovid-Medline, Ovid-Embase, National Guideline Clearinghouse, Guideline International Network) and domestic databases (KoreaMed, KMbase, and KoMGI) were searched for guidelines. The retrieved articles were analyzed by 2 reviewers, and articles were selected using well-established inclusion criteria.

Results

The search identified 294 articles, of which 3 were selected as relevant guidelines. Based on those 3 guidelines, 3 recommendations for implant planning were derived.

Conclusion

We recommend radiography or cone-beam computed tomography (CBCT) scanning for individual patients judged to require a cross-sectional image after reading of a panoramic X-ray image and a conventional intraoral radiological image. Various steps should be taken to raise awareness of these recommendations among clinicians and the public, and K-CIG should be regularly reviewed and revised.

Sinus floor elevation or referral for further diagnosis and therapy: A comparison of maxillary sinus assessment by ENT specialists and dentists using cone beam computed tomography

OBJECTIVES

To compare ear, nose, and throat (ENT) specialists and dentists assessing health or pathology of maxillary sinuses using cone beam computed tomography (CBCT).

MATERIAL AND METHODS

Two ENT specialists and two oral surgeons assessed 100 CBCT datasets of healthy patients referred for dental implant placement in the posterior maxilla and decided on the possibility of sinus floor elevation or the necessity for further diagnostic examinations based solely on radiographic findings. Inter-rater agreements within the same specialty were calculated with Cohen's kappa and overall agreements with Fleiss kappa, and factors influencing the decisions taken were evaluated using regression analyses.

RESULTS

The correlation between all four raters was generally fair to moderate. The intra-specialty comparison showed a lower correlation between dentists than between ENT specialists. Absence of membrane thickening and total or subtotal sinus opacification showed the highest predictive value for a consensus in favor of sinus floor elevation and ENT referral, respectively. Flat membrane thickening with an irregular surface morphology was associated with disagreement between the examiners. Dome-shaped membrane thickenings were often considered as to be referred by dentists but not by ENTs.

CONCLUSION

The assessment of maxillary sinuses using CBCT imaging exhibited unsatisfactory agreement between ENT specialists and oral surgeons. Referral guidelines based on accidental CBCT findings that aim to diagnose relevant sinus pathologies early and avoid unnecessary diagnostics and/or therapies are needed, and an initial proposal for such recommendations is provided. Further research on correct interpretation of sinus findings and a validation of the present recommendations are required.

Complete-arch fixed reconstruction by means of guided surgery and immediate loading: a retrospective clinical study on 12 patients with 1 year of follow-up

Background

Guided implant surgery is considered as a safe and minimally invasive flapless procedure. However, flapless guided surgery, implant placement in post-extraction sockets and immediate loading of complete-arch fixed reconstructions without artificial gum are still not throughly evaluated. The aim of the present retrospective clinical study was to document the survival and success of complete-arch fixed reconstructions without artificial gum, obtained by means of guided surgery and immediate loading of implants placed also in fresh extraction sockets.

Methods

A total of 12 patients (5 males and 7 females, with a mean age of 50.0 ± 13.8) were enrolled in this study. Implant planning was performed with a guided surgery system (RealGuide®, 3Diemme, Como, Italy), from which 3D-printed surgical templates were fabricated. All implants (Esthetic Line-EL®, C-Tech, Bologna, Italy) were placed through the guides and immediately loaded by means of a temporary fixed full-arch restoration without any artificial gum; the outcome measures were implant stability at placement, implant survival, complications, prosthetic success, soft-tissue stability, and patient satisfaction.

Results

One hundred ten implants (65 of them post-extractive) were placed flapless through a guided surgery procedure and then immediately loaded by means of provisional fixed full arches. Successful implant stability at placement was achieved in all cases. After a provisionalization period of 6 months, 72 fixed prosthetic restorations were delivered. Only 2 implants failed to osseointegrate and had to be removed, in one patient, giving a 1-year implant survival rate of 98.2% (108/110 surviving implants); 8/12 prostheses did not undergo any failure or complication during the entire follow-up period. At the 1-year follow-up control, soft-tissue was stable in all patients and showed satesfactory aesthetic results.

Conclusions

Within the limits of this study, complete-arch fixed reconstruction by means of guided surgery and immediate loading of implants placed in fresh extraction sockets appears to be a reliable and successful procedure. Further long-term prospective studies on a larger sample of patients are needed to confirm these positive outcomes.

CONE BEAM CT IN DENTAL IMPLANT PLANNING: HOW CLOSE ARE PATIENT DOSIMETRY RESULTS WITH DATA FROM PHANTOM STUDIES FOUND IN LITERATURE?

Advantages of Cone Beam Computed Tomography (CBCT) include high-quality 3D imaging and reduced radiation exposure with relatively low cost. In this study, patient radiation exposure in CBCT implant planning dentistry was measured in terms of Kerma Area Product (KAP). Data were obtained from 217 CBCT scans on 168 individuals using a CS9300 Carestream system. Scans were made using 80-90 kVp, 4-5 mA, 8 and 13.3 s exposure time (depending on voxel size) and a fixed field of view (FOV) of 10 × 10 cm2 (medium). Mean KAP was estimated using two voxel sizes 180 × 180 × 180 μm3 and 200 × 200 × 200 μm3 and found to be 399 and 314 mGycm2, respectively. Corresponding KAP values found in literature ranged between 210 and 2140 mGycm2. Mean E was estimated using conversion coefficient factors found in literature, according to FOV size and tube voltage value and found to range between 24 and 161 μSv.

The maxillary sinus: physiology, development and imaging anatomy

OBJECTIVES

The maxillary sinus is of paramount importance for otolaryngologists, rhinologists, oral and maxillofacial surgeons, head and neck and dental and maxillofacial radiologists. A comprehensive review article concerning the physiology, development and imaging anatomy was undertaken.

METHODS

Relevant literature pertaining to the physiology of the sinonasal cavity, development of the paranasal sinuses and imaging anatomy of the maxilla and maxillary sinus from 2000 to 2019 was reviewed. Emphasis was placed on literature from the last 5 years.

RESULTS

Extensive recent research using imaging has provided new insights into the development of the maxillary sinus, the other paranasal sinuses and the midface. The fundamental physiological concept of mucociliary clearance and its role in sinus health is emphasized. The paranasal sinuses are an integral part of a common mucosal organ formed by the upper and lower airway.An in-depth understanding of the soft-tissue and neurovascular relationships of the maxillary sinus to the deep fascial spaces and branches of the trigeminal nerve and external carotid artery respectively is required to evaluate and report imaging involving the maxillary sinus.Sinusitis of rhinogenic, rather than odontogenic origin, originates from nasal inflammation followed by anterior ethmoid disease and secondary obstruction of the ostiomeatal unit. The role of anatomical variants that predispose to this pattern of disease is discussed in detail with illustrative examples.The maxillary sinus is intimately related to the roots of the posterior maxillary teeth; the high frequency of mucosal disease and sinusitis of odontogenic aetiology is now well recognized. In addition, an understanding of the anatomy of the alveolar process, morphology of the alveolar recess of the maxillary sinus and neurovascular supply are essential both for deliberate surgical intervention of the sinus and complications related to oral surgical procedures.

CONCLUSIONS

An understanding of the fundamental principles of the development, physiology, anatomy and relationships of the maxillary sinus as depicted by multi-modality imaging is essential for radiologists reporting imaging involving the paranasal sinuses and midface.

Generative Noise Reduction in Dental Cone-Beam CT by a Selective Anatomy Analytic Iteration Reconstruction Algorithm

Dental cone-beam computed tomography (CBCT) is a powerful tool in clinical treatment planning, especially in a digital dentistry platform. Currently, the “as low as diagnostically acceptable” (ALADA) principle and diagnostic ability are a trade-off in most of the 3D integrated applications, especially in the low radio-opaque densified tissue structure. The CBCT benefits in comprehensive diagnosis and its treatment prognosis for post-operation predictability are clinically known in modern dentistry. In this paper, we propose a new algorithm called the selective anatomy analytic iteration reconstruction (SA2IR) algorithm for the sparse-projection set. The algorithm was simulated on a phantom structure analogous to a patient’s head for geometric similarity. The proposed algorithm is projection-based. Interpolated set enrichment and trio-subset enhancement were used to reduce the generative noise and maintain the scan’s clinical diagnostic ability. The results show that proposed method was highly applicable in medico-dental imaging diagnostics fusion for the computer-aided treatment planning, because it had significant generative noise reduction and lowered computational cost when compared to the other common contemporary algorithms for sparse projection, which generate a low-dosed CBCT reconstruction.

Proximity of Vascular Bone Channel in the Lateral Sinus Wall to Root Apices of Maxillary First Molars: A Cone-beam Computed Tomographic Analysis

INTRODUCTION

Apical surgery is frequently indicated in maxillary first molars. Occasionally, a vascular anastomosis in the lateral maxillary sinus wall can be observed during surgery. The aim of this study was to examine the distance between the vascular bone channel (VBC) and the root apices of maxillary first molars using cone-beam computed tomographic imaging.

METHODS

Cone-beam computed tomographic images of 104 maxillary first molars were oriented in the coronal plane to evaluate the distance between the roots and the VBC. The measurements were only recorded in relation to the buccal roots. In addition, demographic parameters and further measurements such as the diameter of the VBC and the proximity to the periapical pathology were evaluated.

RESULTS

A total of 210 VBCs were assessed. The mean distance from the VBC to the apices of the buccal roots of the maxillary first molars was 6.18 mm ± 3.84 mm. The VBC was mostly located intrasinusally (74.3%) and only rarely superficially (0.5%). The diameter of the VBC was on average 0.88 ± 0.32 mm.

CONCLUSIONS

In this study, the VBC was usually found closer to the mesiobuccal than to the distobuccal root apex. During preparation of the access window, the existence of the VBC should be kept in mind because the mesiobuccal roots of maxillary first molars undergo apical surgery to the buccally positioned roots only.

Frequency, location, and morphology of accessory maxillary sinus ostia: a retrospective study using cone beam computed tomography (CBCT)

PURPOSE

To evaluate the reliability of cone beam computed tomography (CBCT) imagining in the assessment of the frequency, location, and morphological characteristics of accessory maxillary ostia (AMOs), and to analyze a potential association with sinus and dentoalveolar pathologies.

METHODS

CBCT scans with bilateral maxillary sinuses that were acquired from September 2016 to September 2018 were initially screened. A total of 160 CBCT scans (320 sinuses) that fulfilled the inclusion criteria were included for further analysis. The presence, location, and morphological characteristics of the AMOs were evaluated in axial, coronal, and sagittal CBCT views. The findings were correlated with age, gender, sinus, and dentoalveolar pathology to assess for potential influencing factors on AMOs.

RESULTS

An AMO was present in 151 (47.2%) of the 320 sinuses. Most of the AMOs were located within the region of the nasal fontanelle or hiatus semilunaris (81.1%) presenting with an ovaloid (48.4%) or a round shape (39.0%). The average length of the AMOs was 2.33 ± 1.42 mm, occupying an area of 3.43 ± 4.51 mm², respectively. Morphological changes of the maxillary sinus mucosa were positively associated with length and area of AMOs. Furthermore, the status of the dentition in the posterior maxilla seemed to be an influencing factor on AMO shape.

CONCLUSIONS

Nearly half of the maxillary sinuses assessed in the present study population had an AMO. Pathologies of the maxillary sinus seem to have an impact on AMOs, which is demonstrated here by morphological changes of the sinus mucosa being associated with an increase in length and area of accessory ostia.

The dimensions of the facial alveolar bone at tooth sites with local pathologies: a retrospective cone-beam CT analysis

OBJECTIVE

To assess the impact of various local pathologies on facial alveolar bone dimensions at tooth sites.

MATERIALS AND METHODS

Cone-beam computed tomography images of 60 patients were analyzed. Healthy teeth and teeth with local pathologies (i.e., endodontically treated, periodontally diseased teeth, and teeth with periapical lesions) were included. The thickness of the facial alveolar bone was measured at five locations: (1) the bone crest (W0), (2) 25% (W25), (3) 50% (W50), (4) 75% (W75) of the distance from the bone crest to the root apex (A), and (5) in the A region (W100). The results were considered statistically significant at p < 0.0008 (adjustment according to the statistical correction for multiple testing).

RESULTS

A total of 1174 teeth (707 healthy and 467 with the local pathologies) were assessed. Periodontally diseased maxillary premolars and anterior teeth in the mandible in the W0 position, as well as maxillary molars in the W25 position, tended to have a lower facial bone thickness when compared to the healthy teeth (0.68 mm vs. 0.84 mm, p = 0.008; 0.47 mm vs. 0.55 mm, p = 0.004; and 1.27 mm vs. 1.72 mm; p = 0.009, respectively). In contrast, the observed tendency pointed towards thicker facial bone wall for the periodontally diseased mandibular anterior teeth in the W50 position (0.74 vs. 0.52, p = 0.001). Healthy maxillary molars tended to display a thicker facial alveolar bone compared to the teeth with local pathologies in the W25, W50, and W75 positions (p = 0.001, p = 0.005, and p = 0.004, respectively).

CONCLUSIONS

The present analysis has indicated that local pathologies are commonly associated with a compromised socket morphology.

CLINICAL RELEVANCE

The facial bone thickness was particularly reduced at periodontally diseased teeth, which may challenge implant therapy.

Accuracy of linear measurements on CBCT images related to presurgical implant treatment planning: A systematic review

OBJECTIVE

The aim of this systematic review was to identify, review, analyze, and summarize available evidence on the accuracy of linear measurements when using maxillofacial cone beam computed tomography (CBCT) specifically in the field of implant dentistry.

MATERIAL AND METHODS

The search was undertaken in April 2017 in the National Library of Medicine database (Medline) through its online site (PubMed), followed by searches in the Cochrane, EMBASE, ScienceDirect, and ProQuest Dissertation and Thesis databases. The main inclusion criterion for studies was that linear CBCT measurements were performed for quantitative assessment (e.g., height, width) of the alveolar bone at edentulous sites or measuring distances from anatomical structures related to implant dentistry. The studies should compare these values to clinical data (humans) or ex vivo and/or experimental (animal) findings from a "gold standard."

RESULTS

The initial search yielded 2,516 titles. In total, 22 studies were included in the final analysis. Of those, two were clinical and 20 ex vivo investigations. The major findings of the review indicate that CBCT provides cross-sectional images that demonstrate high accuracy and reliability for bony linear measurements on cross-sectional images related to implant treatment. A wide range of error has been reported when performing linear measurements on CBCT images, with both over- and underestimation of dimensions in comparison with a gold standard. A voxel size of 0.3 to 0.4 mm is adequate to provide CBCT images of acceptable diagnostic quality for implant treatment planning.

CONCLUSIONS

CBCT can be considered as an appropriate diagnostic tool for 3D preoperative planning. Nevertheless, a 2 mm safety margin to adjacent anatomic structures should be considered when using CBCT. In clinical practice, the measurement accuracy and reliability of linear measurements on CBCT images are most likely reduced through factors such as patient motion, metallic artefacts, device-specific exposure parameters, the software used, and manual vs. automated procedures.

Visibility, location, and morphology of the primary maxillary sinus ostium and presence of accessory ostia: a retrospective analysis using cone beam computed tomography (CBCT)

OBJECTIVES

This retrospective study evaluated the visibility, location, and morphology of the primary maxillary ostium (PMO), as well as the presence and number of accessory maxillary ostia (AMO) in the maxillary sinus using cone beam computed tomography (CBCT).

MATERIALS AND METHODS

CBCT scans with a large field of view with both maxillary sinuses entirely visible, acquired from February 2016 to February 2018, were initially screened. Patients were included if there was no history of surgical intervention/trauma in the sinus region. Two observers evaluated the CBCTs for PMO and AMOs independently. PMO and AMOs were evaluated in axial, coronal, and sagittal CBCT views. In case of disagreement, a third observer served as a referee. The findings were correlated with age, gender, condition of the sinus mucosa, and status of the dentition to assess for potential influencing factors.

RESULTS

A total of 184 patients (368 maxillary sinuses) were included. PMO was present and patent in 346 (94.0%) of the 368 analyzed sinuses. Most of the PMOs were located above the attachment of and in the middle third of the inferior turbinate (76.1%) and exhibited a slit shape (71.1%). An AMO was present in 167 (45.5%) of the 368 analyzed sinuses, and 66 (17.9%) sinuses had multiple AMOs. Gender and sinus mucosa morphology were found to be influencing factors for the patency of the PMO. Furthermore, gender seems to be influencing the presence of an AMO.

CONCLUSIONS

Most of the analyzed maxillary sinus cavities in the present population had a patent PMO. Being male and having morphological changes of the sinus mucosa were factors associated with a reduced prevalence of a patent PMO.

CLINICAL RELEVANCE

A maxillary sinus with pathological findings of the mucosa seems to have a reduced prevalence of patent PMOs. Therefore, clinicians should take care to assess any clinical and radiographical sign indicating a potential maxillary sinusitis prior to surgical interventions in this region, especially in cases with planned sinus floor elevation.

Dimensional accuracy of cone beam CT with varying angulation of the jaw to the X-ray beam

OBJECTIVES

Cone beam CT (CBCT) machines do not always allow for patients to be scanned in the ideal position for image acquisition. This study aimed to investigate the influence of the position/angulation of the mandible relative to the X-ray beam of a CBCT machine.

METHODS

Five sequential CBCT scans were captured of a human mandible at each angulation of 10°, 20°, 30°, and 40° using a coronal and sagittal positioning. Inspection software utilized a best-fit alignment to automatically calculate the three-dimensional variation at 15 standardized points of interest.

RESULTS

Statistically significant differences were found between the dimensional accuracy of CBCT scans taken at 10° (26.3 µm) of coronal angulation, as well as those taken at 20° (-17.3 mm) and 30° (35.2 mm) of sagittal angulations (p < 0.001, 0.016, and <0.001, respectively). The largest deviations in accuracy included an overall maximum deviation of 490 mm.

CONCLUSIONS

The position of the mandible with respect to the X-ray beam has a clinically insignificant effect on dimensional accuracy, up to the maximum angle of 40° assessed.

Distances of root apices to adjacent anatomical structures in the anterior maxilla: an analysis using cone beam computed tomography

OBJECTIVES

The aim was to assess the anatomical relationship of anterior maxillary teeth to the nasal floor in patients referred for apical surgery.

MATERIALS AND METHODS

Cone beam computed tomographic images (CBCT) of 83 patients were analysed retrospectively to quantify the distances between the root apices of maxillary anterior teeth (canine to canine) to the nasal floor or maxillary sinus (whichever was closer). Secondary outcome variables were the distances of the periapical lesion to the nasal floor, distances of the apices to the labial and palatal bone plates as well as to the neighbouring teeth.

RESULTS

A total of 93 teeth (39 central, 35 lateral incisors and 19 canines) were analysed. The mean shortest distances of the apices to the nasal floor (or maxillary sinus) were 8.54 mm for central incisors, 9.49 mm for lateral incisors and 5.39 mm for the canines. The canines exhibited a significantly shorter distance to the nasal floor/maxillary sinus. In the presence of an osteolysis, the distance to the nasal floor was significantly shorter compared to the teeth without lesions. The lateral and central incisors showed significant proximity to each other at the level of the future surgical resection (3 mm from the apex).

CONCLUSIONS

A close proximity between apices and adjacent anatomical structures such as nasal floor, maxillary sinus or adjacent roots could be shown in some cases.

CLINICAL RELEVANCE

CBCT could be a valuable adjunctive imaging tool prior to apical surgery in the anterior maxilla to assess the risk for and decrease the incidence of damage to neighbouring anatomical structures such as the nasal floor, maxillary sinus or adjacent roots.

Is the pneumatisation of the maxillary sinus following tooth loss a reality? A retrospective analysis using cone beam computed tomography and a customised software program

OBJECTIVES

To compare the dimensions of maxillary sinuses in dentate and edentulous patients using cone beam computed tomography (CBCT) scans and a customised software program.

MATERIALS AND METHODS

This study comprised CBCTs of 50 dentate and 50 edentulous posterior maxillae. The observers drew two planar curves in all included sinuses in the frontal, sagittal and axial planes of the respective CBCT scans. The volume (mm³), surface (mm²) and maximum diameter (mm) of the sinuses were calculated using a custom-made software program. The variables analysed were the influence of the state of dentition on sinus dimensions (primary outcome) and the influence of age, gender and side on sinus dimensions; the time needed for analysis; and the intra- and inter-observer agreement (secondary outcomes).

RESULTS

There was no difference in sinus dimensions between dentate and edentulous posterior maxillae. Males had significantly (p < 0.05) greater volume, surface and diameter than females. Strong intra- and inter-observer agreement (Pearson correlation) was found for the calculated sinus dimensions. The time needed per analysis was less than 4 min for both observers.

CONCLUSIONS

Being edentulous did not have an impact on the sinus dimensions, suggesting that there is no ongoing pneumatisation in the sinus after tooth loss. Males had larger sinuses than females in a population older than 30 years.

CLINICAL RELEVANCE

Following tooth loss in the posterior maxilla, vertical bone height is primarily lost due to resorption of the alveolar crest, and not due to pneumatisation of the maxillary sinus. The customised software program was found to be user-friendly and efficient.

Frequency and type of incidentally detected radiodensities in the maxillary sinus: a retrospective analysis using cone beam computed tomography (CBCT)

OBJECTIVES

To evaluate the frequency, location, and characteristics of radiodensities in the maxillary sinus using cone beam computed tomography (CBCT).

MATERIALS AND METHODS

All CBCT scans with a large field of view with both maxillary sinuses entirely visible were initially screened. Patients were included, if there was no suspicion of sinus pathology and no history of surgical intervention/trauma in the sinus region. The location and shape of the radiodensities were evaluated in axial, coronal, and sagittal CBCT views. The findings were correlated with age, gender, condition of the sinus mucosa, and status of the dentition.

RESULTS

A total of 169 patients (338 maxillary sinuses) were included. Radiodensities were found in 35 sinuses (10.4%) of 28 patients (16.6%) with a mean age of 32.0 years. Most of the 35 affected sinuses had one radiodensity (19/54.2%). The radiodensities were typically located at the sinus floor (22/62.9%). Of the sinuses presenting with radiodensities, 17 (48.6%) were exhibiting reactive changes of the Schneiderian membrane. The presence of periodontal pathology was found to be associated with the presence of radiodensities. Age and sinus pathology were influencing factors on the shape of radiodensities, and the status of the dentition was an influencing factor on the number of lesions.

CONCLUSIONS

One-sixth of the patients analyzed had incidentally diagnosed radiodensities in their maxillary sinuses. As almost 50% of the sinuses with radiodensities exhibited a form of chronic rhinosinusitis, the diagnosed ectopic calcifications may have formed as a result of mucosal changes of inflammatory origin. The presence of periodontal pathology was associated with a higher incidence of radiodensities. Nevertheless, this finding has to be interpreted with some caution due to the limited sample size available.

CLINICAL RELEVANCE

Incidentally detected radiodensities in the maxillary sinus are not an infrequent finding in CBCT scans of asymptomatic patients, and are located typically on the sinus floor. Future studies are needed to assess the clinical significance of these findings especially with regard to planned surgical interventions in the posterior maxilla.

Diagnostic performance of cone beam computed tomography in assessing peri-implant bone loss: A systematic review

OBJECTIVES

To evaluate the diagnostic performance of cone beam computed tomography (CBCT) in the assessment of peri-implant bone loss and analyze its influencing factors.

MATERIALS AND METHODS

Clinical and preclinical studies reporting diagnostic outcomes of CBCT imaging of peri-implant bone loss compared to direct reference measurements were sought by searching five electronic databases, PubMed, MEDLINE, EMBASE, Web of Science, and CINAHL Plus, and OpenGrey. QUADAS-2 criteria were adapted for quality analysis of the included studies. A qualitative synthesis was performed. Two meta-analysis models (random-effects and mixed-effects) summarized the area under receiver operating characteristic (AUC) curve observations reported in the selected studies. The mixed-effects meta-analysis model evaluated three possible influencing factors, "defect type," "defect size," and "study effect."

RESULTS

The initial search yielded 3,716 titles, from which 18 studies (13 in vitro and 5 animal) were included. Diagnostic accuracy of CBCT was fair to excellent in detecting in vitro circumferential-intrabony and fenestration defects, but moderate to low for peri-implant dehiscences, and tended to be higher for larger defect sizes. Both, over- and underestimation of linear measurements were reported for the animal models. The meta-analyses included 37 AUC observations from eight studies. The random-effects model showed significant heterogeneity. The mixed-effects model exhibited also significant but lower heterogeneity, and "defect type" and "study effect" significantly influenced the variability of AUC observations.

CONCLUSION

In vitro, CBCT performs well in detecting peri-implant circumferential-intrabony or fenestration defects but less in depicting dehiscences. Influencing factors due to other site-related and technical parameters on the diagnostic outcome need to be addressed further in the future studies.

Comprehensive Treatment of Severe Periodontal and Periimplant Bone Destruction Caused by Iatrogenic Factors

Dental implant success requires placement after periodontal therapy, with adequate bone volume, plaque control, primary stability, control of risk factors, and use of well-designed prostheses. This report describes the surgical and prosthetic management of a patient with severe iatrogenic periodontal/periimplant bone destruction. Methods. A 55-year-old female smoker with fixed partial dentures (FPDs) supported on teeth and implants presented with oral pain, swelling, bleeding, and a 10-year history of multiple implant placements and implants/prosthesis failures/replacements. Radiographs showed severe bone loss, subgingival caries, and periapical lesions. All implants and teeth were removed except implants #4 and #10 which served to retain an interim maxillary restoration. Bone defects were covered with nonresorbable dPTFE membranes. In the mandible, three new implants were placed and loaded immediately with a bar-retained temporary denture. Results. Seven months postoperatively, the bone defects were regenerated, and three additional mandibular implants were placed. All mandibular implants were splinted and loaded with a removable overdenture. Conclusions. In this case, periimplant infection and tissue destruction resulted from the lack of periodontal treatment/maintenance and failure to use evidence-based surgical and loading protocols. Combination therapy resolved the disease and the patient's severe discomfort while providing immediate function and an aesthetic solution.

Frequency, location, and association with dental pathology of mucous retention cysts in the maxillary sinus. A radiographic study using cone beam computed tomography (CBCT)

OBJECTIVES

The purpose of the present study was to evaluate the frequency, locations, and dimensions of mucous retention cysts of the maxillary sinus and analyze potential associated dental pathology.

MATERIALS AND METHODS

A total of 156 cone beam computed tomography (CBCT) scans were included in the analysis, resulting in an evaluation of 310 maxillary sinuses. The presence of mucous retention cysts (MRC) manifesting as dome-shaped radiopacities in the sinus was diagnosed. Their locations were recorded, and dimensions (mm) were measured in coronal and sagittal/axial slices. The patients were grouped into (a) patients/sinuses with MRCs (test), and (b) patients/sinuses with healthy or any other changes (control) for further comparison and evaluation.

RESULTS

There were 40 sinuses (12.9%) with a presence of a total of 56 MRCs. The mean age of involved patients was 29.0 years. The analysis showed that gender, age, sinus side, status of dentition, endodontic status, and periodontal status did not have a significant influence on the presence of MRCs when compared between test and control groups. Age and endodontic status exhibited a significant association with cyst location.

CONCLUSIONS

Most of the sinuses analyzed (79.5%) did not present any MRC, and only 28.6% of the cysts diagnosed were found on the floor of the maxillary sinus. The mean dimension of the MRCs measured 6.28 ± 2.93 mm. No influencing factors on the presence or absence of MRCs were found in the present study.

CLINICAL RELEVANCE

Most MRCs were not located on the floor of maxillary sinus. Future studies should assess their impact on surgical interventions in the sinus.