Radiographic evaluation of a bone substitute material in alveolar ridge preservation for maxillary removable immediate dentures: A randomized controlled trial.

STATEMENT OF PROBLEM: Maxillary bone resorption after multiple extractions can jeopardize the success of an immediate denture, but whether bone volume preservation techniques are effective is unclear. PURPOSE: The purpose of this randomized controlled trial was to evaluate the efficacy of socket grafting with a xenogenic bone substitute in participants receiving maxillary immediate removable complete dentures in terms of bone volume preservation (height and width of the bone ridge). MATERIAL AND METHODS: The study was a single-blinded, randomized controlled clinical trial with 2 balanced parallel arms. Thirty-six participants who had Kennedy Class I edentulous posterior areas bilaterally for at least 3 months and required maxillary immediate removable complete dentures were enrolled. Duplicates of the removable complete denture were made and converted into radiographic and surgical guides. Participants allocated to the test group received deproteinized bovine bone mineral blended with 10% porcine collagen (DBBM-C) in the extraction sockets, and participants in the control group received no grafting material. With a radiographic guide in place, cone beam computed tomography scans were made 10 days after tooth extraction, when the immediate removable complete denture was delivered (D10, baseline), after 3 months (D90), and after 1 year (D365). The scans were superimposed, and measurements were made on the cross-sectional plane of each extraction site. The influence of various prognosis factors associated with bone volume preservation, including the location of tooth extraction, smoking habits, periodontal disease, and operator team, were analyzed. RESULTS: Of 36 participants, 3 were lost to follow-up. The mean ±standard deviation loss of height of the buccal crest was 1.2 ±1.8 mm in the control group and 0.3 ±1.2 mm in the test group after 3 months of healing (P<.001) and 2.1 ±2.0 mm in the control group and 0.7 ±1.4 mm in the test group after 1 year of follow-up (P<.001). Mean ±standard deviation horizontal ridge width change was 1.3 ±1.4 mm in the control group and 0.5 ±0.8 mm in the test group after 3 months (P<.001) and 2.2 ±1.4 mm in the control group and 0.9 ±1.1 mm in the test group after 1 year of follow-up (P<.001). None of the other prognostic factors had a significant effect at either time period. CONCLUSIONS: Grafting DBBM-C into the extraction socket after removing anterior teeth for immediate removable denture therapy resulted in significantly less vertical buccal crest and horizontal ridge resorption as compared with spontaneous socket healing after 1 year of follow-up. This procedure may be useful for preserving bone, especially when a fixed implant-supported prosthesis is planned.

Dacryolithiasis diagnosis and treatment: a 25-year experience using nasal endoscopy.

BACKGROUND: Dacryolith-induced epiphora is caused by a chronic obstruction of the nasolacrimal duct whose aetiology is often specified peroperatively. Dacryocystorhinostomy (DCR) has been often regarded as the gold standard to treat dacryolithiasis. Hasner's valve (HV) incision is a technique to evacuate lithiasis through its physiological track. The purpose of this study was to describe clinical and radiological findings associated with presence of dacryoliths in patients who underwent surgery and to assess the efficacy of these two procedures. METHODS: This study was a comparative interventional multicentric retrospective study including patients referred for an epiphora. The primary endpoint was to determine clinical and endoscopic findings associated with dacryoliths. The secondary endpoints were to evaluate the performance of CT dacryocystography (CT-DG) in the diagnosis of dacryoliths and the success rate of the surgical treatment 6 months postoperatively. RESULTS: 4677 nasolacrimal ducts (NLDs) (78.0% female, mean age 59.2) were included in the study. 3913 underwent DCR, and 764 underwent HV incision. 291 out of 4677 NLDs (6.2%) were found to have dacryoliths. Presence of mucocele associated to a permeable lacrimal system (OR 8.17 (95% 4.62 to 14.44), p<0.01) was associated with presence of lithiasis peroperatively. Success rates at 6 months were 95.6% for endonasal DCR and 94.6% for incision of HV in dacryolithiasis group (p<0.01). CT-DG had a negative predictive value of 96.3% to detect lithiasis (p<0.01). CONCLUSION: Strong clinical and endoscopic findings may improve the imputability of dacryoliths in epiphora. Evacuation of dacryolithiasis through its physiological track was first described in this study in adults with similar results to DCR in patients presenting with dacryolithiasis.

The brainstem in multiple sclerosis: MR identification of tracts and nuclei damage.

OBJECTIVE: To evaluate the 3D Fast Gray Acquisition T1 Inversion Recovery (FGATIR) sequence for MRI identification of brainstem tracts and nuclei damage in multiple sclerosis (MS) patients. METHODS: From april to december 2020, 10 healthy volunteers and 50 patients with remitted-relapsing MS (58% female, mean age 36) underwent MR imaging in the Neuro-imaging department of the C.H.N.O. des Quinze-Vingts, Paris, France. MRI was achieved on a 3 T system (MAGNETOM Skyra) using a 64-channel coil. 3D FGATIR sequence was first performed on healthy volunteers to classify macroscopically identifiable brainstem structures. Then, FGATIR was assessed in MS patients to locate brainstem lesions detected with Proton Density/T2w (PD/T2w) sequence. RESULTS: In healthy volunteers, FGATIR allowed a precise visualization of tracts and nuclei according to their myelin density. Including FGATIR in MR follow-up of MS patients helped to identify structures frequently involved in the inflammatory process. Most damaged tracts were the superior cerebellar peduncle and the transverse fibers of the pons. Most frequently affected nuclei were the vestibular nuclei, the trigeminal tract, the facial nerve and the solitary tract. CONCLUSION: Combination of FGATIR and PD/T2w sequences opened prospects to define MS elective injury in brainstem tracts and nuclei, with particular lesion features suggesting variations of the inflammatory process within brainstem structures. In a further study, hypersignal quantification and microstructure information should be evaluated using relaxometry and diffusion tractography. Technical improvements would bring novel parameters to train an artificial neural network for accurate automated labeling of MS lesions within the brainstem.

[Imaging the brain, from the cell to the organ]. / Imagerie de l'encéphale, de la cellule a l'organe.

Brain imaging has progressed over the centuries, from prehistory (surgical and sculptural empiricism), through the Middle Ages (dissection and drawings), the Renaissance (printing) and the 18th century (Spallanzani and ultrasounds), to the 19th century and the discovery of piezoelectricity by the Curie brothers and X-rays by Röntgen in 1895. The head had finally become transparent! The microscope was used by Ramon Y Cajal for histological and neuropathological brain studies. Marie Curie's discovery of radioisotopes paved the way for advances in in vivo neurophysiology. In the 20th century, technical progress accelerated with the advent of computed tomography. Injected contrast products were initially negative (air for ventriculography and pneumo-encephalography), and subsequently positive (intraventricular then intraarterial iodine, cerebral arteriography, increasingly hyperselective). Neurology and neurosurgery were followed by neuroradiology, stereotaxy, and interventional neuroradiology. G.N. Hounsfield's EMI CT scanner replaced silver salts crystals with computed pixels and voxels. Magnetic resonance imaging (MRI, 1981), which dispenses with the need for X-rays, is evolving at the same pace as computer science itself (Moore's Law) in the form of nanometric biophotonics for example. Diffusion MRI is providing precious information on neuroanatomy (axonal organization of the white matter and neuro-tractography, vascular anatomy), neurochemistry (MRS) and neurophysiology. Functional MRI of sensory activation and resting connectivity, the substrate of thought, is giving fascinating results. Functional stereotactic neurosurgery (for epilepsy, abnormal movements, etc.), stereotactic radiosurgery and endovascular interventional neuroradiology are among the latest approaches.

Efficacy of bone substitute material in preserving volume when placing a maxillary immediate complete denture: study protocol for the PANORAMIX randomized controlled trial.

BACKGROUND: Bone preservation is an essential issue in the context of last teeth extraction and complete edentulism. The intended treatment, whether a complete denture or an implant placement, is facilitated with a voluminous residual ridge. Bone resorption after multiple extractions has not been as well studied as the bone resorption that occurs after the extraction of a single tooth. Recent advances in bone substitute materials have revived this issue. The purpose of this study is to evaluate the interest in using bone substitute material to fill the socket after last teeth extraction in a maxillary immediate complete denture procedure compared with the conventional protocol without socket filling. METHODS/DESIGN: A randomized, controlled, clinical trial was designed. The 34 participants eligible for maxillary immediate complete denture were divided into two groups. Complete dentures were prepared despite persistence of the last anterior teeth. The control group received a conventional treatment including denture placement immediately after extractions. In the experimental group, in addition to the immediate denture placement, a xenograft bone-substitute material (Bio-Oss Collagen®) was placed in the fresh sockets. The primary outcome of the study is to compare mean bone ridge height loss 1 year after maxillary immediate complete denture placement, with or without bone-substitute material, in incisor and canine sockets. The secondary outcomes are to compare the average bone ridge height and width loss for each extraction site. An original quantitative evaluation method using cone beam computed tomography was designed for reproducible measurements, with a radio-opaque denture duplicate. Two independent operators perform the radiologic measurements. DISCUSSION: The immediate complete denture technique limits bone resorption in multiple extraction situations and thus allows better denture retention and better options for implant placement. To compare the benefit of using any bone socket-filling material, we proposed a quantitative evaluation protocol of resorption in the specific case of the last anterior maxillary teeth extraction with immediate denture placement. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02120053 . Registered on 18 April 2014.

[The visual pathways, from anatomical MRI to physiological with (f)MRI and tractography with diffusion tensor MRI (DTMRI)]. / Les voies de la vision, de l'IRM anatomique à la physiologie (IRM(f)) et IRM en tenseur de diffusion (IRMTD) ou tractographie.

Advances in MRI technology have led to a better knowledge of visual pathways (1984-2004), with a new descriptive anatomy and functional model. The authors first describe the technical development of MRI over the last thirty years, then describe and illustrate the new descriptive anatomy. Cephalic MRI reveals brain structures that were previously invisible, on different encephalic planes, in the optic pathways, horizontally from the cornea to the calcarin fissure (neuro-ocular plane (NOP), oblique trans-hemispheric neuro-ocular (OTNOP) and neuro-opto-tractal planes (NOTP)), in their orthogonal orientation upon the oculomotor pathways: head and axonal optic nerve pack (visual deutoneurons in their meninges), optic tracts, lateral geniculate bodies, optic radiations and the calcarian fissure. Comparative anatomy with the rhesus macaque is mentioned. Functional neuroanatomy (physiology) benefits from cine-MRI for ocular motricity (OD MRI), growth by the observation of myelinization in children, blood and CSF circulation by MR angiography, local blood volumes by perfusion imaging, neuronal quantification with inflammation or myelin regeneration by spectroscopy (MRS), brain mapping by functional MR ((f)MRI) measuring local CBF enhancement by paradigmatic stimulations. The recent functional imaging method, tractography (or diffusion tensor MRI (DTMRI)), using diffusion MRI techniques, natural vector calculations with diffusion tensor and software power for morphological and statistical directional results, represents the direction of projection, association and commissural white matter tracts. Normal examples are shown and some common clinical consequences are discussed.

Resolution of homonymous visual field loss documented with functional magnetic resonance and diffusion tensor imaging.

A 68-year-old man developed right homonymous hemianopic paracentral scotomas from acute infarction of the left extrastriate area. He was studied over the ensuing 12 months with visual fields, conventional MRI, functional MRI (fMRI), and diffusion tensor imaging (DTI). As the visual field defect became smaller, fMRI demonstrated progressively larger areas of cortical activation. DTI initially showed that the lesioned posterior optic radiations were completely interrupted. This interruption lessened in time and had disappeared by one year after onset. fMRI and DTI are innovative measures to follow functional and structural recovery in the central nervous system. This is the first reported application of these imaging techniques to acute cerebral visual field disorders.