Michael R. Fenlon

The Isolation of Bifidobacteria from Occlusal Carious Lesions in Children and Adults

The aim of this study was to enumerate and identify bifidobacteria from occlusal carious lesions in permanent and deciduous teeth. Samples of infected dentine were obtained from 24 active occlusal lesions in deciduous teeth and from 15 occlusal lesions in permanent teeth. Plaque samples from sound occlusal surfaces of 12 caries-free adults and 12 children were also obtained. The bifidobacterial strains were isolated in mupirocin-containing selective media, Gram-stained and subcultured for identification. Total bacterial counts were determined using fastidious anaerobic agar, and isolates were identified using genus-specific PCR primers and were confirmed by 16S rRNA sequencing. Bifidobacteria were isolated from 13 of the 15 occlusal lesions in the adults and formed 5.09 ± 2.11% of the total cultivable flora. In the children, bifidobacteria were isolated from 16 of the 24 occlusal lesions and formed 7.4 ± 2.6% of the total flora. No bifidobacteria were isolated from the occlusal surfaces of caries-free adults or children. A total of 424 bifidobacteria were identified and these were Bifidobacteriumdentium, Parascardovia denticolens, Scardoviainopicata, Bifidobacterium longum,Scardovia genomosp. C1 and Bifidobacterium breve. B. dentium was present in 14 out of the 16 bifidobacteria-positive samples from the lesions on the deciduous teeth and in 7 out of the 13 positive lesions in adults (p = 0.04). The present data suggest that bifidobacteria may play a role in the progression of occlusal caries lesions in both children and adults.

Association between Bifidobacteriaceae and the clinical severity of root caries lesions

BACKGROUND/AIMS The isolation of members of the family Bifidobacteriaceae (bifids) from oral samples has been sporadic and a recent cloning study has suggested that they are not detectable in root caries lesions. METHODS To better understand the presence of bifids in root caries we obtained clinical samples (15 of each) from sound exposed root surfaces, leathery remineralizing root lesions, and soft active root lesions. We investigated each for the presence of bifids using a mupirocin-containing selective medium and identified the isolates using 16S recombinant RNA sequencing. RESULTS The proportion of bifids, as a percentage of the total anaerobic count, was significantly related to the clinical status of the sites sampled, being 7.88 +/- 1.93 in the infected dentine from soft lesions, 1.61 +/- 0.91 in leathery lesions, and 0.05 +/- 0.39 in plaque from sound exposed root surfaces. Bifids were isolated from all soft lesions, 13 of 15 leathery lesions, and five of the plaque samples. Bifidobacterium dentium was isolated from four of the plaque samples, from 13 samples from leathery lesions, and from 12 of the 15 samples of infected dentine from the soft active lesions. Parascardovia denticolens and Scardovia genomospecies C1 were each isolated from samples associated with all three clinical conditions whereas Scardovia inopicata and Bifidobacterium subtile were both isolated from the infected dentine of the leathery and soft lesions. Bifidobacterium breve was isolated from the infected dentine of soft root caries lesions. CONCLUSION Bifids may be routinely isolated from root caries lesions using appropriate cultural methods.

Stereo Augmented Reality in the Surgical Microscope

This paper describes the MAGI (microscope-assisted guided interventions) augmented-reality system, which allows surgeons to view virtual features segmented from preoperative radiological images accurately overlaid in stereo in the optical path of a surgical microscope. The aim of the system is to enable the surgeon to see in the correct 3-D position the structures that are beneath the physical surface. The technical challenges involved are calibration, segmentation, registration, tracking, and visualization. This paper details our solutions to these problems. As it is difficult to make reliable quantitative assessments of the accuracy of augmented-reality systems, results are presented from a numerical simulation, and these show that the system has a theoretical overlay accuracy of better than 1 mm at the focal plane of the microscope. Implementations of the system have been tested on volunteers, phantoms, and seven patients in the operating room. Observations are consistent with this accuracy prediction.

Minimally invasive, image-guided, facial-recess approach to the middle ear: demonstration of the concept of percutaneous cochlear access in vitro.

Hypothesis: Image-guided surgery will permit accurate access to the middle ear via the facial recess using a single drill hole from the lateral aspect of the mastoid cortex. Background: The widespread use of image-guided methods in otologic surgery has been limited by the need for a system that achieves the necessary level of accuracy with an easy-to-use, noninvasive fiducial marker system. We have developed and recently reported such a system (accuracy within the temporal bone = 0.76 ± 0.23 mm; n = 234 measurements). With this system, image-guided otologic surgery is feasible. Methods: Skulls (n = 2) were fitted with a dental bite-block affixed fiducial frame and scanned by computed tomography using standard temporal-bone algorithms. The frame was removed and replaced with an infrared emitter used to track the skull during dissection. Tracking was accomplished using an infrared tracker and commercially available software. Using this system in conjunction with a tracked otologic drill, the middle ear was approached via the facial recess using a single drill hole from the lateral aspect of the mastoid cortex. The path of the drill was verified by subsequently performing a traditional temporal bone dissection, preserving the tunnel of bone through which the drill pass had been made. Results: An accurate approach to the middle ear via the facial recess was achieved without violating the canal of the facial nerve, the horizontal semicircular canal, or the external auditory canal. Conclusions: Image-guided otologic surgery provides access to the cochlea via the facial recess in a minimally invasive, percutaneous fashion. While the present study was confined to in vitro demonstration, these exciting results warrant in vivo testing, which may lead to clinically applicable access.

AcouStick: A Tracked A-Mode Ultrasonography System for Registration in Image-Guided Surgery

In this paper, we describe a system for noninvasively determining bone surface points using an optically tracked A-mode ultrasound transducer. We develop and validate a calibration method; acquire cranial surface points for a skull phantom, three volunteers, and one patient; and register these points to surfaces extracted from CT images of the phantom and patient. Our results suggest that the bone surface point localization error of this system is less than 0.5 mm. The target registration error (TRE) of the cranial surface-based registration for the skull phantom was computed by using as a reference gold standard the point-based registration obtained with eight bone-implanted markers. The mean TRE for a 150-surface-point registration is 1.0 mm, and ranges between 1.0 and 1.7 mm for six 25-surface-point registrations. Our preliminary results suggest that accurate, noninvasive, image-to-physical registration of head images may be possible using an A-mode ultrasound-based system.

In vitro assessment of image-guided otologic surgery: Submillimeter accuracy within the region of the temporal bone

OBJECTIVES: Application of image-guided surgery to otology has been limited by the need for sub-millimeter accuracy via a fiducial system that is easily usable (noninvasive and nonobstructive). METHODS: A dental bite-block was fitted with a rigid frame with 7 fiducial markers surrounding each external ear. The temporal bones of 3 cadaveric skulls were removed and replaced with surgical targets arranged in a bulls-eye pattern about the centroid of each temporal bone. The surgical targets were identified both within CT scans and in physical space using an infrared optical tracking system. The difference between positions in CT space versus physical space was calculated as target registration error. RESULTS: A total of 234 independent target registration errors were calculated. Mean ± standard deviation = 0.73 mm ± 0.25 mm. CONCLUSIONS: These findings show that image-guided otologic surgery with submillimeter accuracy is achievable with a minimally invasive fiducial frame. SIGNIFICANCE: In vivo validation of the system is ongoing. With such validation, this system may facilitate clinically applicable image-guided otologic surgery. EBM rating: A.

Isolation and Identification of Bifidobacteriaceae from Human Saliva

ABSTRACT Bifidobacteriaceae were isolated from saliva and infected dentine by using a mupirocin-based selective medium. Of the saliva samples, 94% harbored bifids. The mean concentration (± the standard error) was 4.46 (±0.12) log10(CFU per ml + 1), and the predominant isolates were Bifidobacterium dentium, B. longum, Scardovia inopinata, Parascardovia denticolens, and Alloscardovia omnicolens.

A System for Microscope-Assisted Guided Interventions

We present a system for surgical navigation using stereo overlays in the operating microscope aligned to the operative scene. This augmented reality system provides 3D information about nearby structures and offers a significant advancement over pointer-based guidance, which provides only the location of one point and requires the surgeon to look away from the operative scene. With a previous version of this system, we demonstrated feasibility, but it became clear that to achieve convincing guidance through the magnified microscope view, a very high alignment accuracy was required. We have made progress with several aspects of the system, including automated calibration, error simulation, bone-implanted fiducials and a dental attachment for tracking. We have performed experiments to establish the visual display parameters required to perceive overlaid structures beneath the operative surface. Easy perception of real and virtual structures with the correct transparency has been demonstrated in a laboratory and through the microscope. The result is a system with a predicted accuracy of 0.9 mm and phantom errors of 0.5 mm. In clinical practice errors are 0.5–1.5 mm, rising to 2–4 mm when brain deformation occurs.

Submillimetric target-registration error using a novel, non-invasive fiducial system for image-guided otologic surgery.

Objective: Otologic surgery is undertaken to treat ailments of the ear, including persistent infections, hearing loss, vertigo, and cancer. Typically performed on otherwise-healthy patients in outpatient facilities, the application of image-guided surgery (IGS) has been limited because accurate (<1 mm), non-invasive fiducial systems for otologic surgery have not been available. We now present such a fiducial system. Methods: A dental bite-block was fitted with a custom-designed rigid frame with 7 fiducial markers surrounding each external ear. The bones containing the ear (i.e., the temporal bones) of 3 cadaveric skulls were removed and replaced with discs containing 13 surgical targets arranged in a cross-hair pattern about the centroid of each ear. The surgical targets (26/skull) and fiducial markers (14/skull) were identified both within CT scans using a published algorithm and in physical space using an infrared optical tracking system. Fiducial registration error (FRE), fiducial localization error (FLE), and target registration error (TRE) were calculated. Results: For all trials, root mean square FRE=0.66, FLE=0.72, and TRE=0.77mm. The mean TRE for n=234 independent targets was 0.73 with a standard deviation of 0.25mm. Conclusions: Using a novel, non-invasive fiducial system (the EarMark™), submillimetric accuracy was repeatably achieved. This system will facilitate image-guided otologic surgery.

Locking acrylic resin dental stent for image-guided surgery☆

This article presents a procedure for fabricating a locking acrylic resin dental stent for use in image-guided base-of-skull surgery and neurosurgery. The stent offers advantages over conventional bone screw-anchored systems to surgeons and patients. In view of the increasing use of image guidance in base-of-skull surgery and neurosurgery, prosthodontists will meet a growing demand for this type of device in the future.