A.G. Becking

Complications in the use of sodium hypochlorite during endodontic treatment. Report of three cases

In endodontic treatment, solutions of sodium hypochlorite are widely used as an irrigating agent. It is an effective solvent of both necrotic and vital tissues, which makes it toxic to the surrounding tissues. Complications are rarely reported. Nevertheless, the acute symptoms caused by the toxic reaction must not be underestimated. Causes, treatment, and prevention of complications of sodium hypochlorite use are discussed, and three case reports are presented.

Controversies in orbital reconstruction—I. Defect-driven orbital reconstruction: A systematic review

In the 1980s, computed tomography was introduced as an imaging modality for diagnosing orbital fractures. Since then, new light has been shed on the field of orbital fracture management. Currently, most surgeons are likely to repair orbital fractures based on clinical findings and particularly on data obtained from computed tomography scans. However, an important but unresolved issue is the fracture size, which dictates the extent and type of reconstruction. In other fields of trauma surgery, an increasing body of evidence is stressing the importance of complexity-based treatment models. The aim of this study was to systematically review all articles on orbital reconstruction, with a focus on the indication for surgery and the defect size and location, in order to identify the reconstruction methods that show the best results for the different types of orbital fractures.

Controversies in orbital reconstruction—II. Timing of post-traumatic orbital reconstruction: A systematic review

The timing of orbital reconstruction is a determinative factor with respect to the incidence of potential postoperative orbital complications. In orbital trauma surgery, a general distinction is made between immediate (within hours), early (within 2 weeks), and late surgical intervention. There is a strong consensus on the indications for immediate repair, but clinicians face challenges in identifying patients with minimal defects who may actually benefit from delayed surgical treatment. Moreover, controversies exist regarding the risk of late surgery-related orbital fibrosis, since traumatic ocular motility disorders sometimes recover spontaneously and therefore do not necessarily require surgery. In this study, all currently available evidence on timing as an independent variable in orbital fracture reduction outcomes for paediatric and adult patients was systematically reviewed. Current evidence supports guidelines for immediate repair but is insufficient to support guidelines on the best timing for non-immediate orbital reconstruction.

Predictability in orbital reconstruction. A human cadaver study, part III: Implant-oriented navigation for optimized reconstruction

Navigation-assisted orbital reconstruction remains a challenge, because the surgeon focuses on a two-dimensional multiplanar view in relation to the preoperative planning. This study explored the addition of navigation markers in the implant design for three-dimensional (3D) orientation of the actual implant position relative to the preoperative planning for more fail-safe and consistent results. Pre-injury computed tomography (CT) was performed for 10 orbits in human cadavers, and complex orbital fractures (Class III/IV) were created. The orbits were reconstructed using preformed orbital mesh through a transconjunctival approach under image-guided navigation and navigation by referencing orientating markers in the implant design. Ideal implant positions were planned using preoperative CT scans. Implant placement accuracy was evaluated by comparing the planned and realized implant positions. Significantly better translation (3.53 mm vs. 1.44 mm, p = 0.001) and rotation (pitch: -1.7° vs. -2.2°, P = 0.52; yaw: 10.9° vs. 5.9°, P = 0.02; roll: -2.2° vs. -0.5°, P = 0.16) of the placed implant relative to the planned position were obtained by implant-oriented navigation. Navigation-assisted surgery can be improved by using navigational markers on the orbital implant for orientation, resulting in fail-safe reconstruction of complex orbital defects and consistent implant positioning.

Orthognathic surgery for mentally retarded patients

The surgical treatment of mentally retarded children for esthetic reasons is discussed. In mentally retarded adults a facial deformity can give rise to functional problems; in some cases a facial deformity can stigmatize the mental state. In selected cases orthognathic surgery may offer a solution for either problem. Two cases are reported.

Interobserver variation of single-photon emission computed tomography bone scans in patients evaluated for unilateral condylar hyperactivity

OBJECTIVE This study assessed the quantitative evaluation of the region of interest (ROI) by mean and maximum pixel counts of single-photon emission computed tomography (SPECT) scans in patients with clinical suspicion of unilateral condylar hyperactivity (UCH); the interobserver reliability and the correlation of condylar activity with patient age was determined. METHODS Two independent observers analyzed 67 bone SPECT scans. Maximum and mean activity values within an ROI on the mandibular condyle were analyzed; a cutoff value of 55% was used to determine the qualitative outcome. RESULTS Excellent interobserver agreement was seen for both maximum (kappa 1.0) and mean activity analysis (kappa 0.94). Maximum and mean condylar activities were strongly correlated (r > 0.98). Maximum and mean condylar activity of the normal condyle decreased significantly with increasing age. CONCLUSIONS Maximum and mean condylar activity levels were highly correlated in patients with mandibular asymmetry. An excellent interobserver agreement was found with either maximum or mean condylar activity.

Quantitative Assessment of Orbital Implant Position – A Proof of Concept

Introduction In orbital reconstruction, the optimal location of a predefined implant can be planned preoperatively. Surgical results can be assessed intraoperatively or postoperatively. A novel method for quantifying orbital implant position is introduced. The method measures predictability of implant placement: transformation parameters between planned and resulting implant position are quantified. Methods The method was tested on 3 human specimen heads. Computed Tomography scans were acquired at baseline with intact orbits (t0), after creation of the defect (t1) and postoperatively after reconstruction of the defect using a preformed implant (t2). Prior to reconstruction, the optimal implant position was planned on the t0 and t1 scans. Postoperatively, the planned and realized implant position were compared. The t0 and t2 scans were fused using iPlan software and the resulting implant was segmented in the fused t2 scan. An implant reference frame was created (Orbital Implant Positioning Frame); the planned implant was transformed to the reference position using an Iterative Closest Point approach. The segmentation of the resulting implant was also registered on the reference position, yielding rotational (pitch, yaw, roll) as well as translational parameters of implant position. Results Measurement with the Orbital Implant Positioning Frame proved feasible on all three specimen. The positional outcome provided more thorough and accurate insight in resulting implant position than could be gathered from distance measurements alone. Observer-related errors were abolished from the process, since the method is largely automatic. Conclusion A novel method of quantifying surgical outcome in orbital reconstructive surgery was presented. The presented Orbital Implant Positioning Frame assessed all parameters involved in implant displacement. The method proved to be viable on three human specimen heads. Clinically, the method could provide direct feedback intraoperatively and could improve postoperative evaluation of orbital reconstructive surgery.

Three-Dimensional Imaging of the Face: A Comparison Between Three Different Imaging Modalities

Background Three-dimensional (3D) imaging of the face is being used extensively in medicine for clinical decision making, surgical planning, and research. Nowadays, several companies are offering a broad range of 3D imaging systems, varying in price, method, and mobility. However, most planning and evaluation methods are created and validated solely with one imaging system. Therefore, it is important to analyze possible differences in the 3D surface reconstruction between different systems. Objectives The objective of this study was to analyze differences in the 3D surface reconstruction between three systems: 3dMDface system, Vectra XT, and Artec Eva. Methods Three-dimensional images of the face were acquired from 15 healthy patients with each imaging system. Reproducibility of each device was calculated and a comparison of the Vectra XT and Artec Eva with the 3dMDface was made. Results All 3D imaging devices showed high reproducibility, with a mean difference of 0.18 ± 0.15 mm (3dMDface system), 0.15 ± 0.15 mm (Vectra XT), and 0.26 ± 0.24 mm (Artec Eva). No significant difference in reproducibility was found between the Vectra XT and 3dMDface, while a significant difference was found between 3dMDface and Artec Eva, and between Vectra XT and Artec Eva. The mean difference between 3dMDface and Vectra XT was 0.32 ± 0.26 mm. The mean difference between 3dMDface and Artec Eva was 0.44 ± 1.09 mm. Conclusions All three imaging devices showed high reproducibility and accuracy. Although the Artec Eva showed a significant lower reproducibility, the difference found was not clinically relevant. Therefore, using these different systems alongside each other in clinical and research settings is possible. Level of Evidence 3

Implant-oriented navigation in orbital reconstruction. Part 1 : technique and accuracy study

Intraoperative navigation is frequently used to assess the position of the implant in orbital reconstruction. Interpretation of the feedback from the navigation system to a three-dimensional position of the implant needs to be done by the surgeon, and feedback is only gathered after the implant has been positioned. An implant-oriented navigation approach is proposed, with real-time intuitive feedback during insertion. A technical framework was set up for implant-oriented navigation, with requirements for planning, implant tracking, and feedback. A dedicated navigation instrument was designed and a software tool was developed in order to meet the technical requirements. An accuracy study was performed to investigate the accuracy of the method in comparison to the regular navigation pointer. A proof of concept was provided. The results showed a translation error of 1.12-1.15mm for implant-oriented navigation with regular registration (pointer 0.71-0.98mm) and 0.81mm with accurate registration (pointer 0.54mm). Rotational error was found to be small (<3°). Quantitative and intuitive qualitative feedback could be provided to the surgeon in real-time during insertion of an orbital implant. Following this proof of concept and accuracy study, the implications for the clinical workflow should be evaluated. An implant-oriented approach may form the foundation for augmented reality or robotic-aided implant insertion.