Use of Micro-CT Imaging to Assess Ventral Mandibular Cortical Thickness and Volume in an Experimental Rodent Model With Chronic High-Phosphorus Intake

Adverse effects of high dietary phosphorus on bone health have been observed in both animal and human studies. The aim of the investigation was to examine chronic effects of high phosphorus diet on the apical mandibular cortical thickness and volume in a hystricomorph rodent (Octodon degus) using microcomputed tomography. Male degus were randomly divided into two groups fed by different mineral contents from the age of 12 weeks till the age of 17 months. The micro-CT scanning and wall thickness analysis were applied on the region of the mandible exactly under the apices of the 4th premolar tooth, first molar tooth, and second molar tooth in two animals from each group. General overview and mapping of the ventral mandibular bone thickness revealed pronounced bony mandibular protrusions in all the animals fed a high-phosphorus diet with obvious bone thinning apically to the 4th premolar and first and second molar tooth apices. Mandibular bone volume and thickness located apically to the premolar and molars were statistically significantly smaller/thinner in the group fed by a high phosphorus diet. The thinnest bone measured 0.004 mm, where the mandibular 4th premolar tooth almost perforated the mandibular cortex. Similar studies of metabolic bone disease and its influence on alveolar bone were also published in rats and mice. The influence of different environmental, infectious, or metabolic factors on the growing tooth, alveolar bone formation, and bone pathologies must be done experimentally on growing animals. In contrast, degus have continuously growing dentition, and the effect of any of the above listed factors can be studied in this animal model at any age and for longer time periods.

Unerupted Supernumerary Mandibular Fourth Premolar in a dog

A 2.5-year-old intact male Irish setter was presented for a draining tract associated with the right mandibular first molar tooth (409). Conscious oral examination yielded two draining tracts associated with the right mandibular first molar tooth. No obvious missing teeth or other gross abnormalities associated with the oral cavity were observed. Upon anesthetized radiographic evaluation, the presence of an unerupted, abnormally positioned, supernumerary premolar tooth was observed. The following article describes the extraction of the right mandibular first molar tooth (409) as well as the unerupted supernumerary premolar tooth with associated supernumerary root and the diagnostic approach taken for this uncommon abnormality.

Another Piece of the Puzzle of Anomalous Connectivity in Joubert's Syndrome

We report on the conventional and diffusion tensor imaging (DTI) findings of a 2-year-old child with clinical presentation of Joubert's Syndrome (JS) and brainstem structural abnormalities as depicted by neuroimaging.Conventional magnetic resonance imaging (MRI) showed a “molar tooth” configuration of the brainstem. A band-like formation coursing in an apparent axial plane anterior to the interpeduncular fossa was noted and appeared to partially cover the interpeduncular fossa.DTI maps and three-dimensional (3D) tractography demonstrated a prominent red-encoded white matter bundle anterior to the midbrain. Probable aberrant course of the bilateral corticospinal tracts (CST) was also depicted. Absence of the decussation of the superior cerebellar peduncles and elongated thickened, horizontal superior cerebellar peduncle (SCP) reflecting the molar tooth sign were also shown.Our report and the review of the published cases suggest that DTI and tractography may be very helpful to differentiate between interpeduncular heterotopias and similarly located white matter bundles corroborating the underlying etiology of axonal guidance disorders in the complex group of ciliopathies including JS. Our case represents an important additional puzzle piece to explore the variability of these ciliopathies.

Retinitis pigmentosa and molar tooth sign caused by novel AHI1 compound heterozygote pathogenic variants

Background Joubert syndrome (JS) is a group of rare congenital disorders characterized by cerebellar vermis dysplasia, developmental delay, and retina dysfunctions. Herein, we reported a Chinese patient carrying a new variant in the AHI1 gene with mild JS, and the 3D structure of the affected Jouberin protein was also predicted. Case presentation The patient was a 31-year-old male, who presented difficulty at finding toys at the age of 2 years, night blindness from age of 5 years, intention tremor and walking imbalance from 29 years of age. Tubular visual field and retina pigmentation were observed on ophthalmology examinations, as well as molar tooth sign on brain magnetic resonance imaging (MRI). Whole exome sequence revealed two compound heterozygous variants at c.2105C>T (p.T702M) and c.1330A>T (p.I444F) in AHI1 gene. The latter one was a novel mutation. The 3D protein structure was predicted using I-TASSER and PyMOL, showing structural changes from functional β-sheet and α-helix to non-functional D-loop, respectively. Conclusions Mild JS due to novel variants at T702M and I444F in the AHI1 gene was reported. The 3D-structural changes in Jouberin protein might underlie the pathogenesis of JS.

Examination of the stresses of the implants applied to the atrophic edentulous maxilla on the maxillary bone

Aim: In advanced atrophy of the posterior maxilla, applied zygoma implants increase the success of the surgical procedure by reducing morbidity and procedure time. In our study, using tomographic records, a model with posterior atrophy was obtained in a computer environment, and zygomatic and dental implants in different numbers and localizations were applied to this model. The aim of our study was to choose the most accurate surgical planning according to the stresses arising from the applied forces. Methodology: In our study, one zygoma implant on the right and left in Group 1, two zygoma implants in Group 2, one zygoma implant in Group 3 and one dental implant in the first premolar tooth area, one zygoma implant in Group 4 and one dental implant in the lateral tooth area and one zygoma implant in Group 5 and one dental implant in the lateral and a first premolar tooth area were applied. 150 N were applied vertically to the prosthetic superstructure from the lateral tooth, 1st premolar tooth, 1st molar tooth and 2nd molar tooth. As a result of the applied forces, the maximum stress values ​​in the maxilla molar region were examined by finite element stress analysis. Results: In our study, it was observed that Group 1 had the highest stress value, followed by Group 3. Stress values in Groups 2, 4 and 5 were low and they were measured close to each other. Conclusion: As a result of our study, it was seen that zygomatic and dental implants applied in addition to the zygomatic implant reduce stress and the localization of dental implants affect the stress values. How to cite this article: Gülsün B, Çetindağ A. Examination of the stresses of the implants applied to the atrophic edentulous maxilla on the maxillary bone. Int Dent Res 2021;11(Suppl.1):210-5. https://doi.org/10.5577/intdentres.2021.vol11.suppl1.30 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.