Calcium Silicate-based Sealer Extrusion into the Mandibular Canal: Three Different Recovery Outcomes: A Report of Three Cases

The use of calcium silicate-based sealers (CSS) is increasing in dentistry as result of their favorable properties. The inadvertent extrusion of these sealers into the mandibular canal (MC) can result in temporary or permanent neurosensory alterations. Three different recovery outcomes of CSS extrusion into the MC after endodontic treatment of mandibular molars, confirmed by cone beam computed tomography (CBCT) imaging, are described. In Case 1, CSS from the mesiolingual canal of #31 was extruded into the MC during obturation. The patient reported paresthesia. The symptoms of paresthesia were completely resolved by nine months. In Case 2, CSS from the mesial canals of #30 was extruded into the MC during obturation. "Plasma-like spreading pattern" of the extruded sealer was observed on the radiographs. The patient reported paresthesia and dysesthesia. In addition, the patient complained of hyperalgesia with heat and mechanical allodynia. The symptoms continued to persist during follow up. At 22 months, the patient still reported persistent paresthesia, hyperalgesia and mechanical allodynia, affecting the ability to eat. In Case 3, CSS from the distal canal of #31 was extruded into the MC during obturation. The patient did not report any paresthesia or dysesthesia. All three patients elected a follow up approach and monitoring rather than surgical intervention. These cases illustrate the need for the development of guidelines for the management of iatrogenic CSS extrusion into the MC because such an occurrence may not necessarily result in permanent, temporary or no neurosensory alterations.

The chemical compound 'Heatin' stimulates hypocotyl elongation and interferes with the Arabidopsis NIT1-subfamily of nitrilases

Temperature passively affects biological processes involved in plant growth. Therefore, it is challenging to study the dedicated temperature signalling pathways that orchestrate thermomorphogenesis, a suite of elongation growth-based adaptations that enhance leaf-cooling capacity. We screened a chemical library for compounds that restored hypocotyl elongation in the pif4-2-deficient mutant background at warm temperature conditions in Arabidopsis thaliana to identify modulators of thermomorphogenesis. The small aromatic compound 'Heatin', containing 1-iminomethyl-2-naphthol as a pharmacophore, was selected as an enhancer of elongation growth. We show that ARABIDOPSIS ALDEHYDE OXIDASES redundantly contribute to Heatin-mediated hypocotyl elongation. Following a chemical proteomics approach, the members of the NITRILASE1-subfamily of auxin biosynthesis enzymes were identified among the molecular targets of Heatin. Our data reveal that nitrilases are involved in promotion of hypocotyl elongation in response to high temperature and Heatin-mediated hypocotyl elongation requires the NITRILASE1-subfamily members, NIT1 and NIT2. Heatin inhibits NIT1-subfamily enzymatic activity in vitro and the application of Heatin accordingly results in the accumulation of NIT1-subfamily substrate indole-3-acetonitrile in vivo. However, levels of the NIT1-subfamily product, bioactive auxin (indole-3-acetic acid), were also significantly increased. It is likely that the stimulation of hypocotyl elongation by Heatin might be independent of its observed interaction with NITRILASE1-subfamily members. However, nitrilases may contribute to the Heatin response by stimulating indole-3-acetic acid biosynthesis in an indirect way. Heatin and its functional analogues present novel chemical entities for studying auxin biology.

Arabidopsis immune-associated nucleotide-binding genes repress heat tolerance at the reproductive stage by inhibiting the unfolded protein response and promoting cell death

Plants are vulnerable to heat stress, especially during reproductive development. The heat shock response (HSR) in the cytosol and nucleus, as well as the unfolded protein response (UPR) in the endoplasmic reticulum (ER), are two mechanisms that enable plants to survive heat stress. Excessive heat or ER stresses lead to cell death when the UPR cannot repair stress damage, but the means by which cell survival or death is determined remains unclear. In this study, we used a genome-wide association study (GWAS) to identify that a cluster of five Immune-associated nucleotide-binding protein (IAN) genes (IAN2 to IAN6) is responsible for variation in heat tolerance at the reproductive stage in Arabidopsis thaliana. These IAN genes have both unique and overlapping functions in the negative regulation of heat tolerance, and their loss of function singly or in combination confers increased heat tolerance, measured by a lower number of barren siliques and a higher seedling survival rate under heat. The loss of rice IAN1 gene function also leads to enhanced heat tolerance, suggesting a conserved function of plant IANs. Transcriptome analysis revealed enhanced expression of HSR and UPR genes, as well as reduced cell death, under heat and ER stress in the mutant of IAN6, a major effect member in Arabidopsis. Furthermore, the IAN proteins were found to promote cell death induced by heat stress, ER stress, and cell death-inducing molecules. Thus, the Arabidopsis IAN genes repress heat tolerance, probably through the HSR and UPR and by enhancing the cell death pathway. The IAN2 to IAN6 proteins are partially localized to the ER, suggesting a direct role in the UPR and UPR-mediated cell death. In addition, a natural IAN6 variant from more heat-tolerant Arabidopsis accessions confers greater heat tolerance and induces less cell death compared with the natural variant from less heat-tolerant accessions. The heat-tolerant IAN6 variant is associated with a higher maximum temperature of the warmest month at its collection sites compared with the heat-sensitive variant. Taken together, these results reveal an important role of Arabidopsis IAN2 to IAN6 genes in the regulation of the HSR, UPR, and cell death, and suggest that their natural variations have adaptive functions in heat tolerance.

Genome-wide discovery, and computational and transcriptional characterization of an AIG gene family in the freshwater snail Biomphalaria glabrata, a vector for Schistosoma mansoni

Background

The AIG (avrRpt2-induced gene) family of GTPases, characterized by the presence of a distinctive AIG1 domain, is mysterious in having a peculiar phylogenetic distribution, a predilection for undergoing expansion and loss, and an uncertain functional role, especially in invertebrates. AIGs are frequently represented as GIMAPs (GTPase of the immunity associated protein family), characterized by presence of the AIG1 domain along with coiled-coil domains. Here we provide an overview of the remarkably expanded AIG repertoire of the freshwater gastropod Biomphalaria glabrata, compare it with AIGs in other organisms, and detail patterns of expression in B. glabrata susceptible or resistant to infection with Schistosoma mansoni, responsible for the neglected tropical disease of intestinal schistosomiasis.

Results

We define the 7 conserved motifs that comprise the AIG1 domain in B. glabrata and detail its association with at least 7 other domains, indicative of functional versatility of B. glabrata AIGs. AIG genes were usually found in tandem arrays in the B. glabrata genome, suggestive of an origin by segmental gene duplication. We found 91 genes with complete AIG1 domains, including 64 GIMAPs and 27 AIG genes without coiled-coils, more than known for any other organism except Danio (with > 100). We defined expression patterns of AIG genes in 12 different B. glabrata organs and characterized whole-body AIG responses to microbial PAMPs, and of schistosome-resistant or -susceptible strains of B. glabrata to S. mansoni exposure. Biomphalaria glabrata AIG genes clustered with expansions of AIG genes from other heterobranch gastropods yet showed unique lineage-specific subclusters. Other gastropods and bivalves had separate but also diverse expansions of AIG genes, whereas cephalopods seem to lack AIG genes.

Conclusions

The AIG genes of B. glabrata exhibit expansion in both numbers and potential functions, differ markedly in expression between strains varying in susceptibility to schistosomes, and are responsive to immune challenge. These features provide strong impetus to further explore the functional role of AIG genes in the defense responses of B. glabrata, including to suppress or support the development of medically relevant S. mansoni parasites.

Nerve regeneration techniques respecting the special characteristics of the inferior alveolar nerve

PURPOSE

The aim of this study was to examine the in situ regeneration of the inferior alveolar nerve (IAN) in its bony channel, using autologous tissue in combination with a recombinant human nerve growth factor (rhNGF).

MATERIALS AND METHODS

A total of 20 New Zealand rabbits were randomly divided into five groups. Following dissection of the IAN, the animals underwent reconstruction either with muscle tissue (groups 1 and 2) or with fat tissue (groups 3 and 4). In group 5 (control), the dissected nerve was resected and reconstructed by placement of the reversed autologous segment. After 2 and 4 weeks, 1 mL rhNGF was locally injected in groups 1 and 3. Nerve function was monitored by measuring the jaw-opening reflex using electromyography for a period of 24 weeks.

RESULTS

Regeneration of the nerve was achieved in all groups, but preoperative threshold values were not achieved. Comparing the experimental groups to the control, there was a significant difference in favor of the autologous nerve reconstruction. Differences between the experimental groups remained statistically not significant.

CONCLUSION

Regeneration of the IAN with autologous tissue is possible, but without achieving preoperative thresholds. Additional injection of a growth factor seems to improve the speed of regeneration for fat and muscle grafts.

Variation in Location of the Mandibular Foramen/Inferior Alveolar Nerve Complex Given Anatomic Landmarks Using Cone-beam Computed Tomographic Scans

INTRODUCTION

The inferior alveolar nerve (IAN) injection is 1 of the most commonly administered and useful injections in the field of dentistry. Practitioners use intraoral anatomic landmarks, which vary greatly among patients. The objective of this study was to assist practitioners by identifying a range of normal variability within certain landmarks used in delivering IAN anesthesia.

METHODS

A total of 203 randomly selected retrospective cone-beam computed tomographic scans were obtained from the Midwestern University Dental Institute cone-beam computed tomographic database. InVivoDental5.0 volumetric imaging software (Anatomage, San Jose, CA) was used to measure 2 important parameters used in locating the mandibular foramen (MF)/IAN complex: (1) the angle from the contralateral premolar contact area to the MF and (2) the distance above the mandibular occlusal plane to the center of the MF. The variation of these measurements was compared with established reference values and statistically analyzed using a 1-sample t test.

RESULTS

The angle from the contralateral premolar contact area to the MF for the right and left sides was 42.99° and 42.57°, respectively. The angulations varied significantly from the reference value of 45° (P < .001). The minimum height above the mandibular occlusal plane for the right and left sides was 9.85 mm and 9.81 mm, respectively. The heights varied significantly from the minimum reference value of 6 mm but not the maximum reference value of 10 mm (P < .001).

CONCLUSIONS

Orienting the syringe barrel at an angulation slightly less than 45° and significantly higher than 6 mm above the mandibular occlusal plane can aid in successfully administering anesthesia to the MF/IAN complex.

Anaesthesia of the inferior alveolar and lingual nerves following subcondylar fractures of the mandible

A retrospective chart review of 387 patients with condylar and subcondylar fractures revealed 2 cases of inferior alveolar nerve (IAN) and lingual nerve (LN) anaesthesia following the subcondylar fracture. Only 5 cases have been reported previously. The mechanism of action remains unknown but a review of the literature and an analysis of 120 dry human skulls supported the hypothesis that compression of the mandibular nerve at a high level, close to the foramen ovale, could cause anaesthesia. This complication is rare, because it requires compression at a particular angle. The antero-median angulation of the condyle must be close to the foramen ovale, and the fracture must be a unilaterally displaced fracture. The presence of an enlarged lateral pterygoid plate appeared to enhance the risk of compression. The IAN and LN anaesthesia could be resolved after open reduction of the fracture and IAN and LN anaesthesia constitute a strict indication for an early open fracture reduction.

Indirect post-implant lesions of the inferior alveolar nerve. Radiological and biomechanical findings

THE AIM OF THE WORK.: The mandibular canal, if it is affected by different illnesses, often shows typical radiological changes, made up of widespread hypodensity, an increase in its diameter and disappearing walls. This study aims to verify the reliability of such radiological signs in the cases of later post-operative lesions of the mandiblular canal. MATERIALS AND METHOD.: The study includes 16 patients, 9 males and 7 females, with an average age of 54 years, who underwent an operation to rehabilitate the mandible with a prosthetic implant for a total of 37 implants. All the subjects underwent an Orthopantograph due to the appearance of painful radicular symptoms some time after the operation. RESULTS.: In 36 cases out of 37 we found, with the Orthopantograph, a slight increase in the calibre of the mandibular canal compared to the controlateral. In 10 subjects we observed hypodensity of the canal itself, while in 6 subjects the canal passages were no longer recognisable. CONCLUSION.: The radiological indications of damage of the inferior alveolar nerve (IAN) are reliable even in the case of indirect post-implant lesions.